Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2018	Mar. 25, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	BIOC
Entity Registrant Name	BIOCEPT INC
Entity Central Index Key	0001044378
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		18,817,076
Entity Public Float			$ 13,554,726

Balance Sheets - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash	$ 3,423,373	$ 2,146,611
Accounts receivable, net	1,574,325	1,193,426
Inventories, net	587,222	498,702
Prepaid expenses and other current assets	425,961	416,600
Total current assets	6,010,881	4,255,339
Fixed assets, net	2,739,422	3,123,567
Total assets	8,750,303	7,378,906
Current liabilities:
Accounts payable	2,039,718	1,269,953
Accrued liabilities	1,928,393	1,752,363
Supplier financings		61,226
Current portion of equipment financings	641,536	408,992
Current portion of credit facility, net		1,168,811
Total current liabilities	4,609,647	4,661,345
Non-current portion of equipment financings	985,015	1,150,063
Non-current portion of deferred rent	113,122	271,464
Total liabilities	5,707,784	6,082,872
Commitments and contingencies (see Note 16)
Shareholders’ equity:
Preferred stock, $0.0001 par value, 5,000,000 shares authorized; no shares and 4,417 shares issued and outstanding at December 31, 2017 and 2018, respectively.
Common stock, $0.0001 par value, 150,000,000 shares authorized; 1,181,179 shares issued and outstanding at December 31, 2017; 4,629,174 shares issued and outstanding at December 31, 2018.	463	118
Additional paid-in capital	223,499,634	196,545,523
Accumulated deficit	(220,457,578)	(195,249,607)
Total shareholders’ equity	3,042,519	1,296,034
Total liabilities and shareholders’ equity	$ 8,750,303	$ 7,378,906

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	4,417	0
Preferred stock, shares outstanding	4,417	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	4,629,174	1,181,179
Common stock, shares outstanding	4,629,174	1,181,179

Statements of Operations and Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Net revenues	$ 3,250,298	$ 5,068,663
Costs and expenses:
Cost of revenues	10,051,735	9,345,122
Research and development expenses	4,468,572	3,364,747
General and administrative expenses	7,074,024	7,189,529
Sales and marketing expenses	5,914,706	6,343,971
Total costs and expenses	27,509,037	26,243,369
Loss from operations	(24,258,739)	(21,174,706)
Other income/(expense):
Interest expense, net	(310,976)	(482,623)
Other income		51,216
Total other income/(expense):	(310,976)	(431,407)
Loss before income taxes	(24,569,715)	(21,606,113)
Income tax expense	(1,886)	(7,624)
Net loss and comprehensive loss	(24,571,601)	(21,613,737)
Deemed dividend related to warrants down round provision	(636,370)
Net loss attributable to common shareholders	$ (25,207,971)	$ (21,613,737)
Weighted-average shares outstanding used in computing net loss per share attributable to common shareholders:
Basic	2,798,243	916,599
Diluted	2,798,243	916,599
Net loss per common share:
Basic	$ (9.01)	$ (23.58)
Diluted	$ (9.01)	$ (23.58)

Statements of Shareholders' Equity - USD ($)	Total	March 2017 Registered Direct Offering [Member]	August 2017 Private Placement [Member]	December 2017 Registered Direct Offering [Member]	January 2018 Financing Transaction [Member]	August 2018 Rights Offering [Member]	September 2018 Registered Direct Offering [Member]	Prefunded Warrants [Member]	Common Stock [Member]	Common Stock [Member] March 2017 Registered Direct Offering [Member]	Common Stock [Member] August 2017 Private Placement [Member]	Common Stock [Member] December 2017 Registered Direct Offering [Member]	Common Stock [Member] January 2018 Financing Transaction [Member]	Common Stock [Member] September 2018 Registered Direct Offering [Member]	Common Stock [Member] Prefunded Warrants [Member]	SeriesA Convertible Preferred Stock [Member]	SeriesA Convertible Preferred Stock [Member] August 2018 Rights Offering [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] March 2017 Registered Direct Offering [Member]	Additional Paid-in Capital [Member] August 2017 Private Placement [Member]	Additional Paid-in Capital [Member] December 2017 Registered Direct Offering [Member]	Additional Paid-in Capital [Member] January 2018 Financing Transaction [Member]	Additional Paid-in Capital [Member] August 2018 Rights Offering [Member]	Additional Paid-in Capital [Member] September 2018 Registered Direct Offering [Member]	Additional Paid-in Capital [Member] Prefunded Warrants [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2016	$ 658,661								$ 58									$ 174,294,473								$ (173,635,870)
Beginning balance, shares at Dec. 31, 2016									583,313
Net loss	(4,432,707)
Ending balance at Mar. 31, 2017	10,418,069
Beginning balance at Dec. 31, 2016	658,661								$ 58									174,294,473								(173,635,870)
Beginning balance, shares at Dec. 31, 2016									583,313
Stock-based compensation expense	1,247,481																	1,247,481
Shares issued for restricted stock units, shares									5,194
Shares issued upon exercise of common stock warrants	7,498,535								$ 23									7,498,512
Shares issued upon exercise of common stock warrants, shares									227,228
Shares and warrants issued, net of issuance costs		$ 8,559,959	$ 2,023,939	$ 2,921,196						$ 15	$ 5	$ 16							$ 8,559,944	$ 2,023,934	$ 2,921,180
Shares and warrants issued, net of issuance costs, shares										144,000	48,889	164,167
Fractional shares issued upon one-for-thirty reverse stock split									$ 1									(1)
Fractional shares issued upon one-for-thirty reverse stock split, shares									8,388
Net loss	(21,613,737)																									(21,613,737)
Ending balance at Dec. 31, 2017	1,296,034								$ 118									196,545,523								(195,249,607)
Ending balance, shares at Dec. 31, 2017									1,181,179
Beginning balance at Mar. 31, 2017	10,418,069
Net loss	(5,693,151)
Ending balance at Jun. 30, 2017	7,342,257
Net loss	(5,821,306)
Ending balance at Sep. 30, 2017	4,026,079
Net loss	(5,666,573)
Ending balance at Dec. 31, 2017	1,296,034								$ 118									196,545,523								(195,249,607)
Ending balance, shares at Dec. 31, 2017									1,181,179
Net loss	(6,356,404)
Ending balance at Mar. 31, 2018	8,507,714
Beginning balance at Dec. 31, 2017	1,296,034								$ 118									196,545,523								(195,249,607)
Beginning balance, shares at Dec. 31, 2017									1,181,179
Stock-based compensation expense	623,412																	623,412
Shares issued for restricted stock units									$ 1									(1)
Shares issued for restricted stock units, shares									5,833
Shares issued upon exercise of common stock warrants								$ 1,200							$ 12										$ 1,188
Shares issued upon exercise of common stock warrants, shares															120,000
Deemed dividends related warrants downround provision	636,370																	636,370								(636,370)
Shares and warrants issued, net of issuance costs					$ 13,342,819	$ 10,097,862	$ 2,252,793						$ 110	$ 64			$ 1					$ 13,342,709	$ 10,097,861	$ 2,252,729
Shares and warrants issued, net of issuance costs, shares													1,095,153	642,438			11,587
Shares issued upon conversion of preferred stock									$ 158							$ (1)		(157)
Shares issued upon conversion of preferred stock, shares									1,584,571							(7,170)
Net loss	(24,571,601)																									(24,571,601)
Ending balance at Dec. 31, 2018	3,042,519								$ 463									223,499,634								(220,457,578)
Ending balance, shares at Dec. 31, 2018									4,629,174							4,417
Beginning balance at Mar. 31, 2018	8,507,714
Net loss	(6,153,101)
Ending balance at Jun. 30, 2018	2,527,568
Deemed dividends related warrants downround provision	636,370
Net loss	(6,047,784)
Ending balance at Sep. 30, 2018	8,938,408
Net loss	(6,014,312)
Ending balance at Dec. 31, 2018	$ 3,042,519								$ 463									$ 223,499,634								$ (220,457,578)
Ending balance, shares at Dec. 31, 2018									4,629,174							4,417

Statements of Cash Flows - USD ($)	12 Months Ended
Statements of Cash Flows - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Cash Flows from Operating Activities
Net loss	$ (24,571,601)	$ (21,613,737)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	800,905	575,717
Inventory reserve	(38,499)	(50,532)
Stock-based compensation	623,412	1,247,481
Non-cash interest expense related to credit facility and other financing activities	29,426	45,788
Increase/(decrease) in cash resulting from changes in:
Accounts receivable, net	(380,899)	(1,064,457)
Inventory	(50,021)	100,875
Prepaid expenses and other current assets	488,505	518,863
Accounts payable	601,872	349,932
Accrued liabilities	460,972	236,927
Accrued interest	(202,609)	78,649
Deferred rent	(116,681)	(76,232)
Net cash used in operating activities	(22,355,218)	(19,650,726)
Cash Flows from Investing Activities:
Purchases of fixed assets	(145,253)	(1,400,180)
Net cash used in investing activities	(145,253)	(1,400,180)
Cash Flows from Financing Activities:
Net proceeds from issuance of common stock and warrants	25,693,474	13,505,094
Proceeds from exercise of common stock warrants	1,200	7,498,535
Net proceeds from sale-leaseback transaction		150,848
Payments on equipment financings	(160,381)	(166,348)
Payments on supplier and other third-party financings	(559,092)	(465,279)
Payments on credit facility	(1,197,968)	(1,934,665)
Net cash provided by financing activities	23,777,233	18,588,185
Net increase/(decrease) in Cash	1,276,762	(2,462,721)
Cash at Beginning of Period	2,146,611	4,609,332
Cash at End of Period	3,423,373	2,146,611
Cash paid during the period for:
Interest	605,485	358,471
Income taxes	$ 4,517	$ 5,273

Statements of Cash Flows (Parenthetical) - USD ($)							12 Months Ended
Statements of Cash Flows (Parenthetical) - USD ($)	Sep. 20, 2018	Aug. 13, 2018	Jan. 30, 2018	Dec. 08, 2017	Aug. 09, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Financed insurance premium through third party financing							$ 488,000	$ 451,000
Cancelled insurance premiums previously financed through third-parties, remaining principal outstanding balance							0
Fixed assets purchased under capital lease obligations							279,000	719,000
Fixed assets with an aggregate net book value								34,000
Purchases of fixed assets							$ 25,000	$ 31,000
Issuance of unregistered warrants to purchase shares of common stock	762,438	2,549,140		8,208	47,821	72,000
Exercise price of unregistered warrants		$ 4.53	$ 3.16	$ 25.50	$ 45.00	$ 75.00	$ 3.16
Unregistered warrants to purchase common stock, period				5 years	5 years	5 years
Issuance of unregistered warrants to purchase shares of common stock, grant date fair value	$ 2,000,000	$ 8,400,000	$ 9,700,000	$ 100,000	$ 1,500,000	$ 2,800,000
Offering fees and costs recorded within common stock issuance costs as an offset to additional paid in capital	$ 300,000	$ 1,400,000	$ 1,400,000	$ 428,000	$ 176,000	$ 728,000
Class of warrant or rights, first exercisable date				Jun. 05, 2018
Class of warrant or rights, expiration date				Dec. 05, 2022
Public offering, number of common stock and warrants issued	642,438		1,095,153
Stock price	$ 3.285		$ 13.50
Class of warrant or rights, term		5 years	5 years
Aggregate units sold under right offering		11,587
Aggregate shares sold under right offering	642,438
Warrant exercisable for share of common stock		1
Gross proceeds from offering	$ 2,500,000	$ 11,600,000
Preferred stock converted to shares of common stock							1,584,571
Deemed dividend related to warrants down round provision							$ 636,370
Private Placement [Member]
Exercise price of unregistered warrants	$ 3.16
Class of warrant or rights, term	5 years
Warrant exercisable for share of common stock	1
Prefunded Warrants [Member]
Exercise price of unregistered warrants	$ 3.275
Issuance of warrants to purchase shares of common stock	120,000
Change in exercise price of warrants	$ 0.01
Warrants [Member]
Exercise price of unregistered warrants			$ 15.00
Class of warrant or rights, first exercisable date							Mar. 24, 2019
Class of warrant or rights, expiration date							Mar. 24, 2024
Class of warrant or rights, term			5 years
Aggregate warrants sold under right offering		2,549,140
Series A Preferred Stock [Member]
Aggregate shares sold under right offering		11,587
Shares converted							7,170
Maximum [Member]
Issuance of unregistered warrants to purchase shares of common stock			1,095,153
Issuance of warrants to purchase shares of common stock			1,095,153
Maximum [Member] \| Prefunded Warrants [Member]
Issuance of warrants to purchase shares of common stock	120,000
Maximum [Member] \| Warrants [Member]
Issuance of warrants to purchase shares of common stock			1,095,153

The Company and Business Activities

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

The Company and Business Activities

1. The Company and Business Activities

The Company was founded in California in May 1997 and is an early stage molecular oncology diagnostics company that develops and commercializes proprietary circulating tumor cell, or CTC, and circulating tumor DNA, or ctDNA, assays utilizing a standard blood sample, or liquid biopsy. The Company’s current and planned assays are intended to provide information to aid healthcare providers to identify specific oncogenic alterations that may qualify a subset of cancer patients for targeted therapy at diagnosis, progression or for monitoring in order to identify specific resistance mechanisms. Sometimes traditional procedures, such as surgical tissue biopsies, result in tumor tissue that is insufficient and/or unable to provide the molecular subtype information necessary for clinical decisions. The Company’s assays, performed on blood, have the potential to provide more contemporaneous information on the characteristics of a patient’s disease when compared with tissue biopsy and radiographic imaging. Additionally, commencing in October 2017, the Company’s pathology partnership program, Empower TC, provides the unique ability for pathologists to participate in the interpretation of liquid biopsy results and is available to pathology practices and hospital systems throughout the United States. Further, sales to laboratory supply distributors of our proprietary blood collection tubes, or BCTs, commenced in June 2018, which allow for the intact transport of liquid biopsy samples for research use only, or RUO, from regions around the world.

The Company operates a clinical laboratory that is CLIA-certified (under the Clinical Laboratory Improvement Amendment of 1988) and CAP-accredited (by the College of American Pathologists), and manufactures cell enrichment and extraction microfluidic channels, related equipment and certain reagents to perform the Company’s diagnostic assays in a facility located in San Diego, California. CLIA certification and accreditation are required before any clinical laboratory may perform testing on human specimens for the purpose of obtaining information for the diagnosis, prevention, treatment of disease, or assessment of health. The assays the Company offers are classified as laboratory developed tests under the CLIA regulations.

In July 2013, the Company effected a reincorporation to Delaware by merging itself with and into Biocept, Inc., a Delaware corporation, which had been formed to be and was a wholly-owned subsidiary of the Company since July 23, 2013.

Liquidity and Going Concern Uncertainty

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Liquidity and Going Concern Uncertainty

2. Liquidity and Going Concern Uncertainty

As of December 31, 2018, cash totaled $3.4 million and the Company had an accumulated deficit of $220.5 million. For the years ended December 31, 2017 and 2018, the Company incurred net losses of $21.6 million and $24.6 million, respectively. At December 31, 2018, the Company had aggregate net interest-bearing indebtedness of $1.6 million of which $642,000 was due within one year, whereas at December 31, 2017, the Company had aggregate net interest-bearing indebtedness of approximately $3.1 million, of which approximately $2.0 million was due within one year, in addition to approximately $2.7 million of other non-interest-bearing current liabilities. Additionally, in February 2016, the Company signed a firm, non-cancelable, and unconditional commitment in an aggregate amount of $1,062,500 with a vendor to purchase certain inventory items, payable in minimum quarterly amounts of $62,500 through May 2020, under which approximately $341,000 remained outstanding at December 31, 2018 (see Note 16). These factors raise substantial doubt about the Company’s ability to continue as a going concern for the one-year period following the date that these financial statements were issued. The accompanying financial statements and notes have been prepared assuming that the Company will continue as a going concern. The accompanying financial statements and notes do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that may result from the possible inability of the Company to continue as a going concern.

While the Company is currently in the commercialization stage of operations, the Company has not yet achieved profitability and anticipates that it will continue to incur net losses for the foreseeable future. Historically, the Company’s principal sources of cash have included proceeds from the issuance of common and preferred stock, proceeds from the exercise of warrants to purchase common stock, proceeds from the issuance of debt, and revenues from laboratory services. The Company’s principal uses of cash have included cash used in operations, payments relating to purchases of property and equipment and repayments of borrowings. The Company expects that the principal uses of cash in the future will be for continuing operations, hiring of sales and marketing personnel and increased sales and marketing activities, funding of research and development, capital expenditures, and general working capital requirements. The Company expects that, as revenues grow, sales and marketing and research and development expenses will continue to grow, albeit at a slower rate and, as a result, the Company will need to generate significant growth in net revenues to achieve and sustain income from operations.

In May 2015, the SEC declared effective a shelf registration statement filed by the Company, which expired in May 2018. The shelf registration statement allowed the Company to issue any combination of its common stock, preferred stock, debt securities and warrants from time to time for an aggregate initial offering price of up to $50 million, subject to certain limitations for so long as its public float was less than $75 million. Pursuant to an exclusive placement agent agreement dated April 25, 2016 between the Company and H.C. Wainwright & Co., LLC, or Wainwright, and a securities purchase agreement dated April 29, 2016 between the Company and the purchasers’ signatory thereto, the Company received approximately $4.3 million of net cash proceeds upon the sale of its common stock and warrants to purchase its common stock. Subsequent to the closing of this offering on May 4, 2016, no warrants sold in this offering have been exercised, with approximately $4.5 million in gross warrant proceeds remaining outstanding and available to be exercised at $117.00 per share until their expiration in May 2021. Pursuant to an exclusive placement agent agreement dated March 28, 2017 between the Company and Roth Capital Partners, LLC as lead placement agent, and WestPark Capital and Chardan Capital as co-placement agents, a securities purchase agreement for an offering of 144,000 shares of the Company’s common stock was effected under this registration statement at a per share price of $64.50. In a concurrent private placement, the Company sold unregistered warrants to purchase up to an aggregate of 72,000 shares of its common stock that closed concurrently with the offering common stock sold pursuant to this shelf registration statement, of which none have been subsequently exercised. All warrants sold in this offering have a per share exercise price of $75.00 and expire on October 1, 2022. The closing of the sale of these securities to the purchasers occurred on March 31, 2017, when the Company received approximately $8.6 million of net cash proceeds. Pursuant to an exclusive placement agent agreement dated December 5, 2017 between the Company and Dawson James Securities, Inc. as lead placement agent, and WestPark Capital as co-placement agent, a securities purchase agreement for a registered direct offering of 164,166 shares of the Company’s common stock was effected under this registration statement at a per share price of $20.40. The placement agent was issued a warrant to purchase 8,208 shares of common stock at an exercise price of $25.50 per share, which was first exercisable on June 5, 2018 and expires on December 5, 2022. The closing of the sale of these securities occurred on December 8, 2017, when the Company received approximately $2.9 million of net cash proceeds.

Pursuant to a common stock and warrant purchase agreement dated August 9, 2017, the Company received net cash proceeds of approximately $2.0 million as a result of the sale of its common stock and warrants. Subsequent to the closing of this offering, no additional cash proceeds have been received from the exercise of warrants sold in this offering, with approximately $2.2 million in gross warrant proceeds remaining outstanding and available to be exercised at $45.00 per share until their expiration in August 2022.

On January 30, 2018, the Company received net cash proceeds of approximately $13.3 million as a result of the closing of a follow-on public offering. Subsequent to the closing of this offering, no additional cash proceeds have been received from the exercise of warrants sold in this offering, with approximately $16.4 million in gross warrant proceeds remaining outstanding and available to be exercised at $3.16 per share, subject to down round adjustment, until their expiration in January 2023.

In May 2018, the SEC declared effective a shelf registration statement filed by the Company, which expires in May 2021. The shelf registration statement allows the Company to issue any combination of its common stock, preferred stock, debt securities and warrants from time to time for an aggregate initial offering price of up to $50 million, subject to certain limitations for so long as its public float is less than $75 million.

On August 13, 2018, the Company completed a rights offering pursuant to an effective registration statement. Pursuant to the rights offering, the Company sold an aggregate of 11,587 units consisting of an aggregate of 11,587 shares of Series A Preferred Stock and 2,549,140 warrants, with each warrant exercisable for one share of its common stock at an exercise price of $4.53 per share, resulting in net proceeds to the Company of approximately $10.1 million, after deducting expenses relating to the rights offering, including dealer-manager fees and expenses, and excluding any proceeds received upon exercise of any warrants.

On September 20, 2018, the Company completed an offering of 642,438 shares of the Company’s common stock and pre-funded warrants to purchase up to an aggregate of 120,000 shares of its common stock. The shares were sold at a purchase price of $3.285 per share and the pre-funded warrants were sold at a purchase price of $3.275 per pre-funded warrant which represents the per share purchase price for the shares less the $0.01 per share exercise price for each such pre-funded warrant. The net proceeds to the Company from the offering were approximately $2.2 million, after deducting expenses related to the offering including dealer-manager fees and expenses, and excluding any proceeds received upon exercise of any warrants. In addition, in a concurrent private placement, the Company issued to purchasers a warrant to purchase one share of the Company’s common stock for each share and pre-funded warrant purchased for cash in the offering. All warrants issued in this offering initially had an exercise price of $3.16 per share, are exercisable upon the six-month anniversary of issuance and expire five years from such date.

On January 18, 2019, the Company completed an offering of 990,000 shares of the Company’s common stock pursuant to a shelf-registration on Form S-3 that became effective in May 2018. The shares were sold at a purchase price of $2.25 per share and the net proceeds to the Company from this offering were approximately $2.0 million, after deducting expenses related to the offering including dealer-manager fees and expenses.

On February 12, 2019, the Company received net cash proceeds of approximately $6.8 million as a result of the closing of a follow-on public offering of 6,250,000 shares of its common stock and warrants to purchase up to an aggregate of 6,250,000 shares of its common stock at a combined offering price of $1.20 per unit. All warrants sold in this offering have an exercise price of $1.20 per share, are exercisable immediately and expire five years from the date of issuance. In addition, the Company granted warrants to purchase up to an aggregate of 937,500 shares of the Company’s common stock in connection with the partial exercise of the over-allotment option granted to the underwriters. Subsequent to the closing of this offering, no additional cash proceeds have been received from the exercise of warrants sold in this offering. On March 11, 2019, the underwriters exercised their overallotment option for 538,867 shares of the Company’s common stock related to the February 12, 2019 follow-on offering, purchasing shares at $1.20 for net cash proceeds of approximately $601,000.

On March 19, 2019, the Company received net cash proceeds of approximately $7.5 million as a result of completing a registered direct offering of 5,950,000 shares at a negotiated purchase price of $1.37 per share. In addition, in a concurrent private placement, the Company issued to purchasers a warrant to purchase one share of the Company’s common stock for each share purchased for cash in the offering. All warrants issued in this offering have an exercise price of $1.25 per share, are exercisable immediately upon issuance and expire 5.5 years following the date of issuance.

Management’s Plan to Continue as a Going Concern

In order to continue as a going concern, the Company will need, among other things, additional capital resources. Until the Company can generate significant cash from operations, including assay revenues, management’s plans to obtain such resources for the Company include proceeds from offerings of the Company’s equity securities or debt, or transactions involving product development, technology licensing or collaboration. Management can provide no assurances that any sources of a sufficient amount of financing will be available to the Company on favorable terms, if at all.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

3. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying financial statements and notes are prepared in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP, and are prepared on the basis that the Company will continue as a going concern (see Note 2). The accompanying financial statements and notes do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that may result from the possible inability of the Company to continue as a going concern.

On July 6, 2018, the Company’s stockholders approved, and the Company filed, an amendment to the Company’s Certificate of Amendment of Certificate of Incorporation to effect a one-for-thirty reverse stock split of the Company’s outstanding common stock. As such, all references to share and per share amounts in these financial statements and accompanying notes have been retroactively restated to reflect the one-for-thirty reverse stock split, except for the authorized number of shares of the Company’s common stock of 150,000,000 shares, which was not affected by the one-for-thirty reverse stock split.

Going Concern

The Company assesses and determines its ability to continue as a going concern in accordance with the provisions of ASC Topic 205-40, Presentation of Financial Statements—Going Concern, which requires the Company to evaluate whether there are conditions or events that raise substantial doubt about its ability to continue as a going concern within one year after the date that its annual and interim financial statements are issued (see Note 2). Certain additional financial statement disclosures are required if such conditions or events are identified. If and when an entity’s liquidation becomes imminent, financial statements should be prepared under the liquidation basis of accounting. Determining the extent, if any, to which conditions or events raise substantial doubt about the Company’s ability to continue as a going concern, or the extent to which mitigating plans sufficiently alleviate any such substantial doubt, as well as whether or not liquidation is imminent, requires significant judgment by management.

Use of Estimates

The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, management evaluates these estimates and judgments, including those related to accounts receivable, inventories, long-lived assets, income taxes, revenues, stock-based compensation, and the determination of the Company’s ability to continue as a going concern. The Company bases its estimates on various assumptions that it believes are reasonable under the circumstances. Actual results may differ from these estimates under different assumptions or conditions.

Revenue Recognition and Accounts Receivable

The Company's commercial revenues are generated from diagnostic services provided to patient’s physicians and billed to third-party insurance payers such as managed care organizations, Medicare and Medicaid and patients for any deductibles, coinsurance or copayments that may be due. Commencing on March 31, 2017, the Company began to recognize commercial revenue related to billings for assays delivered and billed to Medicare and other third-party payers on an accrual basis when amounts that will ultimately be realized can be estimated upon delivery, whereby prior to March 31, 2017, the Company recognized revenues for its commercial diagnostic services on a cash basis as collected because the amounts ultimately expected to be received could not be estimated upon delivery due to insufficient collection history experience. Commencing on January 1, 2018, the Company recognizes revenue in accordance with ASC 606, Revenue from Contracts with Customers, or ASC 606, which requires that an entity recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. The Company adopted the provisions of ASC 606 using the modified retrospective application method applied to all contracts, which did not impact amounts previously reported by the Company, nor did it require a cumulative effect adjustment upon adoption, as the Company’s method of recognizing revenue under ASC 606 was analogous to the method utilized immediately prior to adoption. Accordingly, there is no need for the Company to disclose the amount by which each financial statement line item was affected as a result of applying the new standard and an explanation of significant changes.

Contracts

For its commercial revenues, while the Company markets directly to physicians, its customer is the patient. Patients do not enter into direct agreements with the Company that commit either them to pay any portion of the cost of the tests if they have not met their annual deductible limit under their insurance policy, if any, or if their insurance otherwise declines to reimburse the Company. Accordingly, the Company establishes a contract with a commercial patient in accordance with other customary business practices, as follows:

•

Approval of a contract is established via the order and accession, which are submitted by the patient’s physician.

•

The Company is obligated to perform its diagnostic services upon receipt of a sample from a physician, and the patient and/or applicable payer are obligated to reimburse the Company for services rendered based on the patient’s insurance benefits.

•

Payment terms are a function of a patient’s existing insurance benefits, including the impact of coverage decisions with CMS and applicable reimbursement contracts established between the Company and payers, unless the patient is a self-pay patient, whereby the Company bills the patient directly after the services are provided.

•

Once the Company delivers a patient’s assay result to the ordering physician, the contract with a patient has commercial substance, as the Company is legally able to collect payment and bill an insurer and/or patient, regardless of payer contract status or patient insurance benefit status.

•

Consideration associated with commercial revenues is considered variable and constrained until fully adjudicated, with net revenues recorded to the extent that it is probable that a significant reversal will not occur.

The Company’s development services revenues are supported by contractual agreements and generated from assay development services provided to entities, as well as certain other diagnostic services provided to physicians, and revenues are recognized upon delivery of the performance obligations in the contract.

Performance Obligations

A performance obligation is a promise in a contract to transfer a distinct good or service, or a bundle of goods or services, to the customer. For its commercial and development services revenues, the Company’s contracts have a single performance obligation, which is satisfied upon rendering of services, which culminates in the delivery of a patient’s assay result(s) to the ordering physician or entity. The duration of time between accession receipt and delivery of a valid assay result to the ordering physician or entity is typically less than two weeks. Accordingly, the Company elected the practical expedient and therefore, does not disclose the value of unsatisfied performance obligations.

Transaction Price

The transaction price is the amount of consideration that the Company expects to collect in exchange for transferring promised goods or services to a customer, excluding amounts collected on behalf of third parties, such as sales taxes. The consideration expected from a contract with a customer may include fixed amounts, variable amounts, or both. The Company’s gross commercial revenues billed, and corresponding gross accounts receivable, are subject to estimated deductions for such allowances and reserves to arrive at reported net revenues, which relate to differences between amounts billed and corresponding amounts estimated to be subsequently collected and is deemed to be variable although the variability is not explicitly stated in any contract. Rather, the implied variability is due to several factors, such as the payment history or lack thereof for third-party payers, reimbursement rate changes for contracted and non-contracted payers, any patient co-payments, deductibles or compliance incentives, the existence of secondary payers and claim denials. The Company estimates the amount of variable consideration using the most likely amount approach to estimating variable consideration for third-party payers, including direct patient bills, whereby the estimated reimbursement for services are established by payment histories on CPT codes for each payer, or similar payer types. When no payment history is available, the value of the account is estimated at Medicare rates, with additional other payer-specific reserves taken as appropriate. Collection periods for billings on commercial revenues range from less than 30 days to several months, depending on the contracted or non-contracted nature of the payer, among other variables. The estimates of amounts that will ultimately be realized from commercial diagnostic services for non-contracted payers require significant judgment by management.

The Company limits the amount of variable consideration included in the transaction price to the unconstrained portion of such consideration. Revenue is recognized up to the amount of variable consideration that is not subject to a significant reversal until additional information is obtained or the uncertainty associated with the additional payments or refunds is subsequently resolved. Differences between original estimates and subsequent revisions, including final settlements, represent changes in the estimate of variable consideration and are included in the period in which such revisions are made. The Company monitors its estimates of transaction price to depict conditions that exist at each reporting date. If the Company subsequently determines that it will collect more consideration than it originally estimated for a contract with a customer, it will account for the change as an increase in the estimate of the transaction price in the period identified as an increase to revenue. Similarly, if the Company subsequently determines that the amount it expects to collect from a customer is less than it originally estimated, it will generally account for the change as a decrease in the estimate of the transaction price as a decrease to revenue, provided that such downward adjustment does not result in a significant reversal of cumulative revenue recognized. Revenue recognized from changes in transaction prices was not significant during the year ended December 31, 2018.

Allocate Transaction Price

For the Company’s commercial revenues, the entire transaction price is allocated to the single performance obligation contained in a contract with a customer. For the Company’s development services revenues, the contracted transaction price is allocated to each single performance obligation contained in a contract with a customer as performed.

Point-in-time Recognition

The Company’s single performance obligation is satisfied at a point in time, and that point in time is defined as the date a patient’s successful assay result is delivered to the patient’s ordering physician or entity. The Company considers this date to be the time at which the patient obtains control of the promised diagnostic assay service.

Contract Balances

The timing of revenue recognition, billings and cash collections results in accounts receivable recorded in the Company’s condensed balance sheets. Generally, billing occurs subsequent to delivery of a patient’s test result to the ordering physician or entity, resulting in an account receivable.

Practical Expedients

The Company does not adjust the transaction price for the effects of a significant financing component, as at contract inception, the Company expects the collection cycle to be one year or less.

The Company expenses sales commissions when incurred because the amortization period is one year or less, which are recorded within sales and marketing expenses.

The Company incurs certain other costs that are incurred regardless of whether a contract is obtained. Such costs are primarily related to legal services and patient communications. These costs are expensed as incurred and recorded within general and administrative expenses.

Disaggregation of Revenue and Concentration of Risk

The composition of the Company’s net revenues recognized during the years ended December 31, 2017 and 2018, disaggregated by source and nature, are as follows:


	For the year ended December 31,
	2017		2018
Net revenues from contracted payers*	$	2,074,596	$	1,348,383
Net revenues from non-contracted payers		2,721,717		1,703,179
Development services revenues		272,350		198,736
Total net revenues	$	5,068,663	$	3,250,298

*Includes Medicare and Medicare Advantage, as reimbursement amounts are fixed and miscellaneous income from CEE-Sure blood collection tubes.


	For the year ended December 31,
	2017		2018
Net commercial revenues recognized upon delivery	$	3,570,337	$	3,051,562
Development services revenues recognized upon delivery		272,350		198,736
Commercial revenues recognized upon cash collection		1,225,976		—
Total net revenues	$	5,068,663	$	3,250,298

The amount of nonrecurring net revenue recorded during the year ended December 31, 2017, had the Company commenced recognizing revenue for commercial diagnostic services upon delivery on or prior to December 31, 2016 instead of on March 31, 2017, was $843,000, and the corresponding decrease in net loss per common share was $0.90. The incremental net revenue and decrease in loss from operations as a result of recognizing revenue on an accrual basis commencing on March 31, 2017, or the total amount of net revenue recorded in excess of the amount of commercial cash collections, was $1,139,000 during the year ended December 31, 2017, and the corresponding decrease in net loss per common share was $1.20, respectively. For the year ended December 31, 2018 all revenues were recognized on an accrual basis.

Concentrations of credit risk with respect to revenues are primarily limited to geographies to which the Company provides a significant volume of its services, and to specific third-party payers of the Company’s services such as Medicare, insurance companies, and other third-party payers. The Company’s client base consists of many geographically dispersed clients diversified across various customer types.

The composition of the Company’s gross and net revenues recognized during the years ended December 31, 2017 and 2018 is as follows:

	For the year ended December 31,
	2017			2018
Commercial revenues recognized upon delivery	$	15,685,069		$	12,505,149
Development services revenues recognized upon delivery		272,350			198,736
Commercial revenues recognized upon cash collection		1,225,976			—
Total gross revenues		17,183,395			12,703,885
Provisions for contractual discounts		(5,805,787	)		(3,937,993	)
Provisions for aged non-patient receivables		(735,709	)		(326,137	)
Provisions for estimated patient receivables		(169,479	)		(66,470	)
Provisions for other payer-specific sales allowances		(5,403,757	)		(5,122,987	)
Net revenues	$	5,068,663		$	3,250,298

A summary of activity in the Company’s gross and net accounts receivable balances, as well as corresponding reserves, during the year ended December 31, 2018 is as follows:

	Balance at			Amounts			Settlements			Balance at
	December 31,			Recognized			Upon			December 31,
	2017			Upon Delivery			Adjudication			2018
Accounts receivable, gross	$	6,937,063		$	12,835,371		$	(11,889,832	)	$	7,882,602
Reserve for contractual discounts		(1,974,849	)		(3,214,615	)		3,011,989			(2,177,475	)
Reserve for aged non-patient receivables		(452,088	)		(994,542	)		880,682			(565,948	)
Reserve for estimated patient receivables		(88,120	)		(135,955	)		208,598			(15,477	)
Reserve for other payer-specific sales allowances		(3,228,580	)		(5,239,961	)		4,919,164			(3,549,377	)
Accounts receivable, net	$	1,193,426		$	3,250,298		$	(2,869,399	)	$	1,574,325

Cash

The Company places its cash with reputable financial institutions that are insured by the Federal Deposit Insurance Corporation, or FDIC. At times, deposits held may exceed the amount of insurance provided by the FDIC. The Company has not experienced any losses in its cash and believes they are not exposed to any significant credit risk.

Fair Value Measurements

The Company uses a three-tier fair value hierarchy to prioritize the inputs used in the Company’s fair value measurements. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets for identical assets; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. The Company believes the carrying amount of cash, accounts receivable, accounts payable and accrued expenses approximate their estimated fair values due to the short-term maturities of these financial instruments. See Note 5 for further details about the inputs and assumptions used to determine fair value measurements.

Concentration of Risk

Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of temporary cash investments.

Concentrations of credit risk with respect to revenues are primarily limited to geographies to which the Company provides a significant volume of its services, and to specific third-party payers of the Company’s services such as Medicare, insurance companies, and other third-party payers. The Company’s client base consists of a large number of geographically dispersed clients diversified across various customer types.

The Company's third-party payers that represent more than 10% of total net revenues in any period presented, as well as their related net revenue amount as a percentage of total net revenues, during the years ended December 31, 2017 and 2018 were as follows:

	For the year ended December 31,
	2017			2018
Medicare and Medicare Advantage		39	%		39	%
Blue Cross Blue Shield		19	%		11	%
United Healthcare		12	%		17	%

The Company's third-party payers that represent more than 10% of total net accounts receivable, and their related net accounts receivable balance as a percentage of total net accounts receivable, at December 31, 2017 and 2018 were as follows:

	For the year ended December 31,
	2017			2018
Blue Cross Blue Shield		27	%		22	%
Medicare and Medicare Advantage		21	%		17	%
United Healthcare		15	%		15	%

The Company operates in one reportable business segment and historically has derived most revenues only from within the United States.

Certain components used in the Company’s current or planned products are currently sourced from one supplier, for which alternative suppliers exist but the Company has not validated the product(s) of such alternative supplier(s), and substitutes for these components may not be obtained easily or may require substantial design or manufacturing modifications.

Inventories

Inventories are valued at the lower of cost or net realizable value. Cost is determined by the average cost method. The Company records adjustments to its inventory for estimated obsolescence or diminution in net realizable value equal to the difference between the cost of the inventory and the estimated net realizable value. At the point of loss recognition, a new cost basis for that inventory is established, and subsequent changes in facts and circumstances do not result in the restoration or increase in that newly established cost basis. In addition, the Company records a liability for firm, non-cancelable, and unconditional purchase commitments with contract manufacturers and suppliers for quantities in excess of the Company’s future demand forecasts consistent with its valuation of excess and obsolete inventory.

Fixed Assets

Fixed assets consist of machinery and equipment, furniture and fixtures, computer equipment and software, leasehold improvements, financed equipment and construction in-process. Fixed assets are stated at cost less accumulated depreciation and amortization. Additions, improvements, and major renewals are capitalized. Maintenance, repairs, and minor renewals are expensed as incurred. Depreciation and amortization are recorded using the straight-line method over the estimated useful lives of the assets, which range from three to seven years. Leasehold improvements are amortized over the life of the lease or the asset, whichever is shorter. Depreciation and amortization expense for the years ended December 31, 2017 and 2018 was approximately $576,000 and $801,000, respectively.

Upon sale or disposal of fixed assets, the accounts are relieved of the cost and the related accumulated depreciation or amortization with any gain or loss recorded to the statement of operations and comprehensive loss.

Fixed assets are reviewed for impairment whenever changes in circumstances indicate that the carrying amount of an asset may not be recoverable. These computations utilize judgments and assumptions inherent in the estimates of future cash flows to determine recoverability of these assets. If the assumptions about these assets were to change as a result of events or circumstances, the Company may be required to record an impairment loss.

Stock-based Compensation

The Company measures and recognizes compensation expense for all stock-based awards made to employees and directors based on their grant date fair values. The Company estimates the fair value of stock option awards on the date of grant using the Black-Scholes option pricing model, while the fair value of restricted stock unit awards, or RSUs, is determined by the Company’s stock price on the date of grant. The value of the portion of the award that is ultimately expected to vest is recognized as expense over the requisite service periods using the straight-line method. In addition, the Company estimates forfeitures at the time of grant and revises these estimates in subsequent periods if actual forfeitures differ from those estimates (see Note 10).

The Company determines the fair value of the stock-based compensation awards granted as either the fair value of the consideration received, or the fair value of the equity instruments issued, whichever is more reliably measurable. All issuances of equity instruments issued to non-employees as consideration for goods or services received by the Company are accounted for based on the fair value of the equity instruments issued. These awards are recorded in expense and additional paid-in capital in shareholders’ equity over the applicable service periods based on the fair value of the options at the end of each period.

Calculating the fair value of stock-based awards requires the input of highly subjective assumptions into the Black-Scholes valuation model. Stock-based compensation expense is calculated using the Company’s best estimates, which involves inherent uncertainties, and the application of management’s judgment. Significant estimates include the expected life of the stock option, stock price volatility and risk-free interest rate.

Research and Development

Research and development costs are expensed as incurred. The amounts expensed in the years ended December 31, 2017 and 2018 were approximately $3,365,000 and $4,469,000, respectively, which includes salaries of research and development personnel.

Income Taxes

The Company provides for income taxes utilizing the liability method. Under the liability method, current income tax expense or benefit is the amount of income taxes expected to be payable or refundable for the current year. A deferred income tax asset or liability is computed for the expected future impact of differences between the financial reporting and tax bases of assets and liabilities and for the expected future tax benefit to be derived from tax credits. Tax rate changes are reflected in the computation of the income tax provision during the period such changes are enacted.

Deferred tax assets are reduced by a valuation allowance when, in management’s opinion, it is more likely than not that some portion or all of the deferred tax assets will not be realized. The Company considers the scheduled reversal of deferred tax liabilities, projected future taxable income, and tax planning strategies in making this assessment. The Company’s valuation allowance is based on available evidence, including its current year operating loss, evaluation of positive and negative evidence with respect to certain specific deferred tax assets including evaluation sources of future taxable income to support the realization of the deferred tax assets. The Company has established a full valuation allowance on the deferred tax assets as of December 31, 2017 and 2018, and therefore has not recognized any income tax benefit or expense in the periods presented.

A tax benefit from uncertain tax positions may be recognized by the Company when it is more-likely-than-not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on the technical merits of the position. Income tax positions must meet a more-likely-than-not recognition threshold to be recognized.

The Company recognizes interest and/or penalties related to income tax matters in income tax expense. There is no accrual for interest or penalties for income taxes on the balance sheets at December 31, 2017 and 2018, and the Company has not recognized interest and/or penalties in the statements of operations and comprehensive loss for the years ended December 31, 2017 and 2018.

Recent Accounting Pronouncements

In January 2016, the FASB issued authoritative guidance requiring, among other things, that certain equity investments be measured at fair value with changes in fair value recognized in net income, that financial assets and financial liabilities be presented separately by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements, that the prior requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet be eliminated, and that a reporting organization is to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. This guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. Early adoption of the instrument-specific credit risk amendment is permitted. The Company adopted this guidance for the fiscal year beginning on January 1, 2018, which did not have a material impact on its financial statements or disclosures.

In February 2016, the FASB issued authoritative guidance, which changes several aspects of the accounting for leases, including the requirement that all leases with durations greater than twelve months be recognized on the balance sheet. The guidance is effective for annual and interim reporting periods in fiscal years beginning after December 15, 2018. Although the Company is in the process of finalizing the impact of adoption of the ASU on its financial statements, the Company will elect the optional transition method to account for the impact of the adoption with a cumulative-effect adjustment in the period of adoption and will not restate prior periods. The Company expects to elect certain practical expedients permitted under the transition guidance. The Company will record a right-of-use asset and liability upon adoption of the guidance. The Company is currently finalizing its review of contracts and may identify additional embedded leases and additional amounts to be recorded.

In August 2016, the FASB issued authoritative guidance clarifying the classification of certain cash receipts and cash payments in the statement of cash flows. This guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years, on a retrospective transition method to each period presented. Early adoption is permitted. The Company adopted this guidance for the reporting period beginning January 1, 2018, which did not have a material impact on its financial statements or disclosures.

In January 2017, the FASB issued authoritative guidance clarifying the definition of a business when evaluating transactions involving acquisitions or disposals of assets or businesses. This guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Certain applications of this guidance are permitted for early adoption. The Company adopted this guidance for the reporting period beginning January 1, 2018, which did not have a material impact on its financial statements or disclosures.

In July 2017, the FASB issued authoritative guidance changing the classification analysis of certain equity-linked financial instruments (or embedded features) with down round features, whereby a down round feature no longer precludes equity classification when assessing whether the instrument is indexed to an entity’s own stock, and also clarifying existing disclosure requirements for equity-classified instruments. This guidance is effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. Early adoption is permitted. The Company early adopted this guidance for the fiscal year beginning on January 1, 2018, which did not have a material impact on its financial statements or disclosures upon adoption, but did result in equity classification for the warrants issued on January 30, 2018, whereby liability classification may have occurred in the absence of the adoption of this guidance due to the existence of a down round feature associated with the exercise price of the warrants, which would have resulted in material impacts to the Company’s financial statements and disclosures.

In August 2017, the FASB issued authoritative guidance that expands and refines hedge accounting for both nonfinancial and financial risk components and align the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. This guidance is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early application is permitted. The Company adopted this guidance for the fiscal year beginning on January 1, 2019 and determined that the adoption of this guidance not will have a material impact on its financial statements or disclosures because the Company does not currently hold any financial instruments accounted for as a hedging activity.

In February 2018, the FASB issued authoritative guidance allowing a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from a tax bill, “H.R.1, An Act to Provide for Reconciliation Pursuant to Titles II and V of the Concurrent Resolution on the Budget for Fiscal Year 2018,” or the Tax Cuts and Jobs Act, enacted on December 22, 2017. These amendments eliminate the stranded tax effects resulting from the Tax Cuts and Jobs Act. However, because these amendments only relate to the reclassification of the income tax effects of the Tax Cuts and Jobs Act, the underlying guidance that requires that the effect of a change in tax laws or rates be included in income from continuing operations is not affected. This guidance also requires certain disclosures about stranded tax effects. This guidance is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The Company adopted this guidance for the fiscal year beginning on January 1, 2019 and determined that the adoption of this guidance will not have a material impact on its financial statements or disclosures because the Company does not currently maintain any stranded tax effects in accumulated other comprehensive income.

In February 2018, the FASB issued authoritative guidance concerning certain fair value option liabilities, equity securities without a readily determinable fair value, and certain equity investments. This guidance is effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years beginning after June 15, 2018. Public entities with fiscal years beginning between December 15, 2017 and June 15, 2018 are not required to adopt these amendments until the interim period beginning after June 15, 2018. The Company adopted this guidance for the interim period beginning on July 1, 2018, which did not have a material impact on its financial statements or disclosures because the Company did not hold any fair value option liabilities, equity securities without a readily determinable fair value, or equity investments.

In June 2018, the FASB issued authoritative guidance simplifying the accounting for nonemployee stock-based compensation and largely aligning such compensation with the accounting requirements for employee stock-based awards. For public companies, this guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. Early adoption is permitted, but no earlier than an entity’s adoption date of guidance on Revenue from Contracts with Customers (Topic 606). The Company adopted this guidance for the fiscal year beginning on January 1, 2019 and determined that the adoption of this guidance will not have a material impact on its financial statements or disclosures.

In November 2018, the FASB issued authoritative guidance clarifying the interaction between Collaborative Arrangements (Topic 808) and Revenue from Contracts with Customers (Topic 606) to address diversity in practice related to how companies account for collaborative arrangements. For public companies, this guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year. Early adoption is permitted, but no earlier than an entity’s adoption date of Revenue from Contracts with Customers (Topic 606). The Company currently intends to adopt this guidance upon the effective date and does not anticipate that the adoption of this guidance will have a material impact on its financial statements or disclosures.

Sales of Equity Securities

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Sales of Equity Securities

4. Sales of Equity Securities

In May 2015, the SEC declared effective a shelf registration statement filed by the Company, which expired on May 21, 2018. The shelf registration statement allowed the Company to issue any combination of its common stock, preferred stock, debt securities and warrants from time to time for an aggregate initial offering price of up to $50 million, subject to certain limitations for so long as the Company’s public float was less than $75 million. Pursuant to an exclusive placement agent agreement dated March 28, 2017 between the Company and Roth Capital Partners, LLC as lead placement agent, and WestPark Capital and Chardan Capital as co-placement agents, a securities purchase agreement for an offering of 144,000 shares of the Company’s common stock was effected under this registration statement at a per share price of $64.50, which closed on March 31, 2017. In a concurrent private placement, the Company sold unregistered warrants to purchase up to an aggregate of 72,000 shares of the Company’s common stock that closed concurrently with the March 2017 offering of common stock sold pursuant the shelf registration statement, of which none have been subsequently exercised. All warrants sold in this offering have a per share exercise price of $75.00 and expire on October 1, 2022. The estimated grant date fair value of these warrants of approximately $2.8 million was recorded as an offset to additional paid-in capital upon the closing of this offering (see Note 5). At the closing of these sales on March 31, 2017, the Company received, approximately $8.6 million after deducting $0.7 million of costs directly associated with the offering that were recorded as an offset to additional paid-in capital under applicable accounting guidance . Pursuant to an exclusive placement agent agreement dated December 5, 2017 between the Company and Dawson James Securities, Inc. as lead placement agent, and WestPark Capital as co-placement agent, a securities purchase agreement for a registered direct offering of 164,166 shares of the Company’s common stock was effected under this registration statement at a per share price of $20.40. The placement agent was issued a warrant to purchase 8,208 shares of common stock at an exercise price of $25.50 per share with an estimated grant date fair value of $0.1 million, which expires on December 5, 2022. The closing of the sale of these securities occurred on December 8, 2017, when the Company received approximately $2.9 million of net cash proceeds after deducting $0.4 million costs directly associated with the offering that were recorded as an offset to additional paid-in-capital under applicable accounting guidance.

Pursuant to a common stock and warrant purchase agreement dated August 9, 2017 between the Company and Ally Bridge LB Healthcare Master Fund Limited, or Ally Bridge, an offering of 48,888 shares of the Company’s common stock and warrants to purchase up to an aggregate of 47,821 shares of common stock was effected at a combined offering price of $45.00 per unit for total gross proceeds to the Company of $2.2 million. All warrants sold in this offering have a per share exercise price of $45.00, are exercisable immediately and expire five years from the date of issuance. The estimated grant date fair value of this warrant of approximately $1.5 million was recorded as an offset to additional paid-in capital upon the closing of this offering (see Note 5). Subsequent to the closing of this offering, no additional cash proceeds had been received from the exercise of warrants sold in this offering. As such, the total increase in capital as a result of the sale of the common stock and warrants has been approximately $2.0 million after deducting $0.2 million of associated costs incurred, which were offset against these proceeds under applicable accounting guidance.

On January 30, 2018, the Company received net cash proceeds of approximately $13.3 million as a result of the closing of a follow-on public offering of 1,095,153 shares of its common stock and warrants to purchase up to an aggregate of 1,095,153 shares of its common stock at a combined offering price of $13.50 per unit with $1.4 million of costs directly associated with the offering recorded as an offset to additional paid-in capital under applicable accounting guidance. All warrants sold in this offering have an exercise price of $3.16 per share, which is subject to down round adjustment, an aggregate estimated grant date fair value of $9.7 million (see Note 4) and expire five years from the date of issuance. Subsequent to the closing of this offering, no additional cash proceeds have been received from the exercise of warrants sold in this offering.

In May 2018, the SEC declared effective a shelf registration statement filed by the Company, which expires in May 2021. The shelf registration statement allows the Company to issue any combination of our common stock, preferred stock, debt securities and warrants from time to time for an aggregate initial offering price of up to $50 million, subject to certain limitations for so long as our public float is less than $75 million.

On August 13, 2018, the Company completed a rights offering. Pursuant to the rights offering, the Company sold an aggregate of 11,587 units consisting of an aggregate of 11,587 shares of Series A Preferred Stock and 2,549,140 warrants, with each warrant exercisable for one share of our common stock at an exercise price of $4.53 per share, resulting in net proceeds to the Company of approximately $10.1 million, after deducting expenses relating to the rights offering, including dealer-manager fees and expenses, and excluding any proceeds received upon exercise of any warrants. Each share of Series A Preferred Stock will be convertible, at the Company’s option at any time on or after the first anniversary of the closing of the Rights Offering or at the option of the holder at any time, into the number of shares of the Company’s common stock, par value $0.0001 per share determined by dividing the $1,000 stated value per share of the Series A Preferred Stock by a conversion price of $4.53 per share. In addition, the conversion price per share is subject to adjustment for stock dividends, distributions, subdivisions, combinations or reclassifications. Holders of Series A Preferred Stock shall be entitled to receive dividends (on an as-if-converted-to-common-stock basis) in the same form as dividends actually paid on shares of the Common Stock when, as and if such dividends are paid on shares of Common Stock. The Series A Preferred Stock have no voting rights. Upon the Company’s liquidation, dissolution or winding-up, whether voluntary or involuntary, holders of Series A Preferred Stock will be entitled to receive out of the assets, whether capital or surplus, of the Company the same amount that a holder of Common Stock would receive if the Series A Preferred Stock were fully converted (disregarding for such purpose any conversion limitations thereunder) to Common Stock, which amounts shall be paid pari passu with all holders of Common Stock. The Company is not obligated to redeem or repurchase any shares of Series A Preferred Stock.

On September 20, 2018, the Company completed an offering of 642,438 shares of the Company’s common stock and prefunded warrants to purchase up to an aggregate of 120,000 shares of its common stock. The shares were sold at a purchase price of $3.285 per share and the pre-funded warrants were sold at a purchase price of $3.275 per pre-funded warrant which represents the per share purchase price for the shares less the $0.01 per share exercise price for each such pre-funded warrant. The net proceeds to the Company from this offering were approximately $2.2 million, after deducting expenses related to the offering including dealer-manager fees and expenses, and excluding any proceeds received upon exercise of any warrants. In addition, in a concurrent private placement, the Company issued to purchasers a warrant to purchase one share of the Company’s common stock for each share and pre-funded warrant purchased for cash in the offering. All warrants issued in this offering have an exercise price of $3.16 per share, are exercisable upon the six-month anniversary of issuance and expire five years from such date.

Fair Value Measurements

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements

5. Fair Value Measurements

The estimated nonrecurring fair value measurements associated with fixed asset purchases recorded as equipment financing obligations totaling approximately $719,000 and $279,000 during the years ended December 31, 2017 and 2018, respectively, were based on information provided by vendors, which involved the use of significant unobservable Level 3 inputs.

The estimated fair value of the terms of the credit facility entered into with Oxford Finance LLC in April 2014, or the April 2014 Credit Facility, at December 31, 2017 and 2018 approximated its carrying value, which was determined using a discounted cash flow analysis. The analysis considered interest rates of instruments with similar maturity dates, which involved the use of significant unobservable Level 3 inputs.

Other Fair Value Measurement

As of the closing of the Company’s March 31, 2017 offering, the estimated grant date fair value of $39.30 per share associated with the warrants to purchase up to 72,000 shares of common stock issued in this offering, or a total of approximately $2.8 million, was recorded as an offset to additional paid-in capital, and was estimated using a Black-Scholes valuation model with the following assumptions:

Stock price	$	63.90
Exercise price	$	75.00
Expected dividend yield		0.00	%
Discount rate-bond equivalent yield		1.93	%
Expected life (in years)		5.00
Expected volatility		80.0	%

As of the closing of the Company’s August 9, 2017 offering, the estimated grant date fair value of $30.90 per share associated with the warrant to purchase up to 47,821 shares of common stock issued in this offering, or a total of approximately $1.5 million, was recorded as an offset to additional paid-in capital, and was estimated using a Black-Scholes valuation model with the following assumptions:

Stock price	$	41.70
Exercise price	$	45.00
Expected dividend yield		0.00	%
Discount rate-bond equivalent yield		1.81	%
Expected life (in years)		5.00
Expected volatility		100.0	%

As of the closing of the Company’s December 8, 2017 offering, the estimated grant date fair value of $15.60 per share associated with the warrant to purchase up to 8,208 shares of common stock issued to the placement agent in this offering, or a total of approximately $0.1 million, was recorded as an offset to additional paid-in capital, and was estimated using a Black-Scholes valuation model with the following assumptions:

Stock price	$	22.20
Exercise price	$	25.50
Expected dividend yield		0.00	%
Discount rate-bond equivalent yield		2.09	%
Expected life (in years)		4.50
Expected volatility		100.0	%

As of the closing of the Company’s January 30, 2018 offering, the grant date fair value of the warrants issued to purchase up to 1,095,153 shares of common stock were estimated to be approximately $8.82 per share, or a total of approximately $9.7 million. The warrants sold in this offering have an exercise price of $3.16 per share, which is subject to down round adjustment, and expire five years from the date of issuance. The fair value of the warrants was at issuance estimated using a Monte Carlo simulation valuation model using Geometric Brownian Motion, incorporating anticipated future financing events, with the following assumptions:

Beginning stock price	$	10.17
Exercise price	$	15.00
Expected dividend yield		0.00	%
Discount rate-bond equivalent yield		2.48	%
Expected life (in years)		5.00
Expected volatility		99.00	%

As of the closing of the Company’s August 13, 2018 rights offering, the grant date fair value of the warrants issued to purchase up to 2,549,140 shares of common stock were estimated to be approximately $3.30 per share, or a total of approximately $8.4 million. The warrants sold in this offering have an exercise price of $4.53 per share and expire five years from the date of issuance. The fair value of the warrants was estimated using a Black-Scholes model, incorporating the following assumptions:

Beginning stock price	$	3.89
Exercise price	$	4.53
Expected dividend yield		0.00	%
Discount rate-bond equivalent yield		2.75	%
Expected life (in years)		5.00
Expected volatility		128.69	%

As of the closing of the Company’s September 20, 2018 offering, the grant date fair value of the warrants issued to purchase up to 762,438 shares of common stock were estimated to be approximately $2.57 per share, or a total of approximately $2.0 million. The warrants sold in this offering have an exercise price of $3.16 per share, and expire five years from the initial exercise date, which is the six-month anniversary of the date of issuance. The fair value of the warrants was estimated using a Black-Scholes model, incorporating the following assumptions:

Beginning stock price	$	2.92
Exercise price	$	3.16
Expected dividend yield		0.00	%
Discount rate-bond equivalent yield		2.77	%
Expected life (in years)		5.50
Expected volatility		130.7	%

Also, included in the September 20, 2018 offering the Company issued 120,000 pre-funded warrants. The pre-funded warrants had an intrinsic value of $350,000. On November 28, 2018, the pre-funded warrants were exercised for total proceeds of approximately $1,200.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Balance Sheet Details

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Balance Sheet Details

6. Balance Sheet Details

The following provides certain balance sheet details:

	December 31,			December 31,
	2017			2018
Fixed Assets
Machinery and equipment	$	2,841,388		$	2,818,583
Furniture and office equipment		147,976			157,391
Computer equipment and software		1,637,034			1,437,408
Leasehold improvements		553,529			570,173
Financed equipment		2,294,762			2,573,955
Construction in process		2,975			116,640
		7,477,664			7,674,150
Less accumulated depreciation and amortization		(4,354,097	)		(4,934,728	)
Total fixed assets, net	$	3,123,567		$	2,739,422
Accrued Liabilities
Accrued interest	$	326,602		$	-
Accrued payroll		224,813			255,426
Accrued vacation		474,953			535,682
Accrued bonuses		375,000			712,574
Accrued sales commissions		104,509			62,767
Current portion of deferred rent		116,681			158,342
Accrued other		129,805			203,602
Total accrued liabilities	$	1,752,363		$	1,928,393

April 2014 Credit Facility

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

April 2014 Credit Facility

7. April 2014 Credit Facility

On April 30, 2014, the Company received net cash proceeds of approximately $4,898,000 pursuant to the execution of the April 2014 Credit Facility. Upon the entry into the April 2014 Credit Facility, the Company was required to pay the lender a facility fee of $50,000 in conjunction with the funding of the term loan. The April 2014 Credit Facility was secured by substantially all of the Company’s personal property other than its intellectual property. The term loan under the April 2014 Credit Facility bore interest at an annual rate of 7.95%. The Company was required to make interest-only payments on the term loan through August 1, 2015. The outstanding term loan under the April 2014 Credit Facility began amortizing at the end of the applicable interest-only period, with monthly payments of principal and interest being made by the Company to the lender in consecutive monthly installments following such interest-only period. The term loan under the April 2014 Credit Facility matured on July 1, 2018. Under the original terms of the underlying agreement, the Company was also required to make a final payment to the lender equal to 5.5% of the original principal amount of the term loan funded.

A warrant to purchase up to 588 shares of the Company’s common stock at an exercise price of $424.80 per share with a term of 10 years was issued to Oxford Finance LLC on April 30, 2014. Issuance costs of approximately $102,000 associated with the term loan under the April 2014 Credit Facility were recorded as a discount to outstanding debt as of the closing date, resulting in net proceeds of approximately $4,898,000. The estimated fair value of the warrant issued of approximately $233,000 was also recorded as a discount to outstanding debt as of the closing date. The discounts and other issuance costs are amortized to interest expense utilizing the effective interest method over the underlying term of the loan, with total unamortized discounts of approximately $33,000 at December 31, 2017. The effective annual interest rate associated with the April 2014 Credit Facility was 13.87% at December 31, 2017. As of December 31, 2017, total remaining principal payments of approximately $1,201,000 were due and such principal balance was paid during the year ended December 31, 2018 with no outstanding principal balance remaining at December 31, 2018.

Equipment Financings

12 Months Ended

Dec. 31, 2018

Capital Lease Obligations [Abstract]

Equipment Financings

8. Equipment Financings

The Company leases certain laboratory equipment under arrangements accounted for as capital leases and classified as equipment financings. The financed equipment is depreciated on a straight-line basis over periods ranging from 5 to 7 years. The total gross value of fixed assets capitalized under such financing arrangements was approximately $2,295,000 and $2,574,000 at December 31, 2017 and 2018, respectively. Total accumulated depreciation related to financed equipment was approximately $759,000 and $1,135,000 at December 31, 2017 and 2018, respectively, and total depreciation expense was approximately $234,000 and $376,000, at December 31, 2017 and 2018, respectively. Fixed asset purchases totaling approximately $719,000 and $279,000 during the years ended December 31, 2017 and 2018, respectively, were recorded as equipment financings.

On September 15, 2017, and as amended on October 17, 2017, the Company executed an equipment financing commitment with a third-party lender for total proceeds to the Company of approximately $151,000, which was funded by the lender on November 2, 2017. Under the terms of the amended equipment financing agreement, which was accounted for as a sale-leaseback transaction, fixed assets previously purchased by the Company with aggregate gross and net book values of approximately $167,000 and $162,000, respectively, were granted as a security interest to the third-party lender, with the principal balance plus interest to be repaid in 36 monthly installments of $4,884 totaling approximately $176,000 through October 2020.

During the year ended December 31, 2017, certain machinery and equipment with aggregate gross, accumulated depreciation, and net book values of approximately $189,000, $155,000 and $34,000, respectively, were exchanged with a lender as partial payment on an outstanding equipment financing obligation balance.

The following schedule sets forth the remaining future minimum lease payments outstanding under financed equipment arrangements, as well as corresponding remaining sales tax and maintenance obligation payments that are expensed and accrued as incurred and due within each respective year ending December 31, as well as the present value of the total amount of the remaining minimum lease payments as of December 31, 2018:

			Maintenance
	Minimum		and Sales Tax
	Lease		Obligation
	Payments		Payments
2019	$	670,896	$	91,285
2020		551,610		72,635
2021		305,006		51,473
2022		264,600		60,832
Thereafter		310,932		45,710
Total payments		2,103,044		321,935
Less amount representing interest		476,493		-
Present value of payments	$	1,626,551	$	321,935

The aggregate weighted average effective annual interest rate related to the equipment financings was 13.51% and 12.53% at December 31, 2017 and 2018, respectively, and the maturity dates on such outstanding arrangements range from June 2018 to September 2024. During the years ended December 31, 2017 and 2018, total interest expense related to equipment financings of $171,000 and $237,000, respectively, was recorded to the Company’s statement of operations and comprehensive loss. At December 31, 2018, the present value of minimum lease payments due within one year was approximately $642,000.

On January 26, 2018, the Company executed a lease agreement with a third-party lender to finance approximately $250,000 of planned fixed asset purchases. Under the terms of the lease agreement, the lease commencement and repayment occurs once the Company has financed equipment purchases for the full amount available under the lease agreement. During the fourth quarter of 2018, the lease agreement was amended to increase the amount available under the lease to a total available cost of $332,000. During 2018, equipment with a total cost of $332,000 was purchased under the lease and the lease term commenced on December 1, 2018. Under the term of the lease, the Company is required to make 22 payments of $15,274 per month during the term of the agreement. Prior to lease commencement in December 2018, the Company paid pro-rated equipment rental charges for equipment financed under this lease totaling approximately $124,000.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

10. Stock-Based Compensation

Equity Incentive Plans

The Company maintains two equity incentive plans: The Amended and Restated 2013 Equity Incentive Plan, or the 2013 Plan, and the 2007 Equity Incentive Plan, or the 2007 Plan. The 2013 Plan includes a provision that shares available for grant under the Company’s 2007 Plan become available for issuance under the 2013 Plan and are no longer available for issuance under the 2007 Plan.

At the Company’s annual meeting of stockholders held on June 28, 2018, the Company’s stockholders approved amendments to the 2013 Plan, which included an increase in the number of non-inducement shares of common stock authorized for issuance under the 2013 Plan by 146,666 shares. As of December 31, 2018, 124,211 shares of the Company’s common stock were authorized exclusively for the issuance of stock awards to employees who have not previously been an employee or director of the Company, except following a bona fide period of non-employment, as an inducement material to the individual’s entering into employment with the Company, as defined under applicable Nasdaq Listing Rules.

As of December 31, 2018, under all plans, a total of 264,098 non-inducement shares were authorized for issuance, 95,258 shares had been issued with 79,300 non-inducement stock options and restricted stock units, or RSUs, underlying outstanding awards, and 168,840 non-inducement shares were available for grant. As of December 31, 2018, 118,368 inducement shares had been issued under the 2013 Plan, with 117,534 inducement stock options and RSUs underlying outstanding awards and 0 inducement shares available for grant.

Stock Options

Non-performance options granted under either plan vest over a maximum period of four years and expire ten years from the date of grant. Non-performance options generally vest either (i) over four years, 25% on the one-year anniversary of the date of grant and monthly thereafter for the remaining three years; or (ii) over four years, monthly vesting beginning month-one after the grant and monthly thereafter.

The fair value of stock options is determined on the date of grant using the Black-Scholes valuation model. For non-performance awards, such value is recognized as expense over the requisite service period, net of estimated forfeitures, using the straight-line method. The amount and timing of compensation expense recognized for performance awards is based on management’s estimate of the most likely outcome and when the achievement of the performance objectives is probable. The determination of the fair value of stock options is affected by the Company’s stock price, as well as assumptions regarding a number of complex and subjective variables. The volatility assumption is based on a combination of the historical volatility of the Company’s common stock and the volatilities of similar companies over a period of time equal to the expected term of the stock options. The volatilities of similar companies are used in conjunction with the Company’s historical volatility because of the lack of sufficient relevant history for the Company’s common stock equal to the expected term. The expected term of employee stock options represents the weighted-average period the stock options are expected to remain outstanding. The expected term assumption is estimated based primarily on the options’ vesting terms and remaining contractual life and employees’ expected exercise and post-vesting employment termination behavior. The risk-free interest rate assumption is based upon observed interest rates on the grant date appropriate for the term of the employee stock options. The dividend yield assumption is based on the expectation of no future dividend payouts by the Company.

The assumptions used in the Black-Scholes pricing model for options granted during the years ended December 31, 2017 and 2018 are as follows:

	2017	2018
Stock and exercise prices	$20.82 - $63.90	$0.86 - $6.00
Expected dividend yield	0.00%	0.00%
Discount rate-bond equivalent yield	1.79% – 2.27%	2.50% - 3.02%
Expected life (in years)	5.12 – 6.09	4.00 - 5.96
Expected volatility	70.0% – 90.0%	100% - 120%

Using the assumptions described above, with stock and exercise prices being equal on date of grant, the weighted-average estimated fair value of options granted in 2017 and 2018 were approximately $1.02 and $1.75 per share, respectively.

A summary of stock option activity for the years ended December 31, 2017 and 2018 is as follows:

	Number of Shares			Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Term in Years
Outstanding at December 31, 2016		29,888		$	264.00		8.5
Granted		58,501		$	44.70
Exercised		—			—
Cancelled/forfeited/expired		(6,746	)	$	143.10
Outstanding at December 31, 2017		81,643		$	113.68		8.8
Granted		142,587		$	2.20
Exercised		—			—
Cancelled/forfeited/expired		(28,410	)	$	57.96
Outstanding at December 31, 2018		195,820		$	41.41		9.2
Vested and unvested expected to vest, December 31, 2018		183,136		$	44.02		9.1

The intrinsic values of options outstanding, options exercisable, and options vested and unvested expected to vest at December 31, 2017 and 2018 were each zero.

On July 25, 2016, the Company entered into an employment agreement with its new Chief Financial Officer, Senior Vice President of Operations and Secretary, or CFO. Pursuant to the terms of this employment agreement, on July 29, 2016 the CFO was granted inducement stock option awards with an exercise price of $58.50 per share to purchase up to (i) 2,222 shares of the Company’s common stock with an estimated grant date fair value of $43.50 per share, 25% of which vested on the one-year anniversary of the commencement of the CFO’s employment with the Company, and remainder of which will vest in equal monthly installments over the following three years, and (ii) 1,111 shares of the Company’s common stock with an estimated grant date fair value of $37.80 per share, which vested upon the Company’s achievement of specified corporate goals for 2016 and the consummation of a specified financing transaction. During the year ended December 31, 2017, 546 shares of the performance option award granted on July 29, 2016 were declared vested by the Company’s Board of Directors, and the remaining 565 shares underlying this award were forfeited.

On May 2, 2017, the Company’s Board of Directors approved the issuance of an aggregate of 18,333 performance stock options to be granted on May 31, 2017 to certain of the Company’s employees and all of its executive officers pursuant to the 2013 Plan, of which 6,666 performance stock options were granted to the Company’s CEO, 3,333 performance stock options were granted to its CFO, and 2,500 performance stock options were granted to each of its Chief Scientific Officer and Senior Medical Director. Each performance stock option granted on May 31, 2017 has an exercise price of $45.00 per share and an estimated grant date fair value of $29.70 per share. On July 6, 2017, the Company’s Compensation Committee of the Board of Directors approved the issuance of an aggregate of 2,500 performance stock options to be granted on July 31, 2017 to certain of the Company’s employees pursuant to the 2013 Plan, of which 2,500 performance stock options were forfeited by December 31, 2017. Each performance stock option granted on July 31, 2017 has an exercise price of $41.70 per share and an estimated grant date fair value of $24.90 per share. Each of the performance stock options granted during the year ended December 31, 2017 were subject to continuing service with vesting as determined by the Company’s Board of Directors or Compensation Committee of the Board of Directors upon the Company’s achievement of specified corporate goals for 2017. Subsequent to the year ended December 31, 2017, none of the performance option awards granted during the year ended December 31, 2017 were declared vested by the Company’s Compensation Committee of the Board of Directors, and the 20,750 shares underlying the remaining outstanding performance stock option awards at December 31, 2017 were forfeited.

Restricted Stock

The fair value of RSUs awarded under either plan is determined by the closing price of the Company’s common stock on the date of grant. For non-performance RSUs, such value is recognized as expense over the requisite service period, net of estimated forfeitures, using the straight-line method. The amount and timing of compensation expense recognized for RSUs is based on management’s estimate of the most likely outcome and when the achievement of the performance objectives is probable.

A summary of RSU activity during 2017 and 2018 is as follows:

	Number of Shares			Weighted Average Grant Date Fair Value
Outstanding at December 31, 2016		5,808		$	80.40
Granted		11,666		$	45.00
Vested and issued		(5,194	)	$	58.80
Forfeited		(250	)	$	63.60
Outstanding at December 31, 2017		12,030		$	56.10
Granted		—		$	—
Vested and issued		(5,835	)	$	45.00
Forfeited		(5,835	)	$	45.00
Outstanding at December 31, 2018		360		$	415.80
Vested and unvested expected to vest, December 31, 2018		360		$	415.80

At December 31, 2018, the intrinsic value of RSUs outstanding and RSUs unvested and expected to vest were approximately $300. Of the 360 RSUs outstanding at December 31, 2018, all were fully vested.

The RSUs granted during the year ended December 31, 2016 vested fully on the one year anniversary of the date of grant and were subject to continuing service by the holders of such RSUs. At December 31, 2017, the intrinsic values of RSUs outstanding and RSUs unvested and expected to vest were approximately $250,000 and $129,000, respectively.

On May 2, 2017, the Company’s Board of Directors approved the issuance of an aggregate of 5,833 time-based RSUs and 5,833 performance RSUs to be granted on May 31, 2017 to certain of the Company’s employees and all of its executive officers pursuant to the 2013 Plan, of which 1,666 time-based RSUs and 833 performance RSUs were granted to its CEO, and 833 time-based RSUs and 833 performance RSUs were granted to certain other executive officers. Each RSU granted on May 31, 2017 has a grant date fair value of $45.00 per share. Vesting of the time-based RSUs granted on May 31, 2017 is subject to continuing service and occurred on the one year anniversary of the vesting commencement date, or May 2, 2018, while the performance RSUs were subject to continuous service and vesting was as determined by the Company’s Board of Directors or its Compensation Committee of the Board of Directors upon the achievement of specified corporate goals for 2017. Subsequent to the year ended December 31, 2017, none of the performance RSUs granted on May 31, 2017 were declared vested by the Company’s Compensation Committee of the Board of Directors, and the 5,833 shares underlying these awards were forfeited.

Stock-based Compensation Expense

The following table presents the effects of stock-based compensation related to equity awards to employees and nonemployees on the statement of operations during the periods presented:

	Years Ended December 31,
	2017		2018
Stock Options
Cost of revenues	$	142,400	$	46,708
Research and development expenses		143,300		133,525
General and administrative expenses		575,741		300,433
Sales and marketing expenses		68,381		78,321
Total expenses related to stock options		929,822		558,987
RSUs
Cost of revenues		48,745		(18,802	)
Research and development expenses		55,941		13,576
General and administrative expenses		160,937		54,302
Sales and marketing expenses		52,036		15,349
Total stock-based compensation	$	1,247,481	$	623,412

Stock-based compensation expense was recorded net of estimated forfeitures of 0% - 8% per annum during the years ended December 31, 2017 and 2018. As of December 31, 2018, total unrecognized share-based compensation expense related to unvested stock options and RSUs, adjusted for estimated forfeitures, was approximately $667,000, and such amount expected to be recognized over a weighted-average period of approximately 2.13 years.

Common Stock Warrants Outstanding

12 Months Ended

Dec. 31, 2018

Other Liabilities Disclosure [Abstract]

Common Stock Warrants Outstanding

11. Common Stock Warrants Outstanding

A summary of equity-classified common stock warrant activity, for warrants other than those underlying unexercised overallotment option warrants, during 2017 and 2018 is as follows:

							Average
					Weighted		Remaining
	Number of				Average Exercise		Contractual
	Shares				Price Per Share		Term in Years
Outstanding at December 31, 2016		387,395		$		57.90		4.6
Issued		128,029		$		60.62
Exercised		(227,228	)	$		33.00
Expired		—		$		—
Outstanding at December 31, 2017		288,196		$		78.86		4.0
Issued		4,526,661		$		3.85
Exercised		(120,000	)	$		0.01
Expired		—		$		—
Outstanding at December 31, 2018		4,694,927		$		8.55		4.4

All warrants outstanding at December 31, 2018 are exercisable, except for the 762,438 warrants issued on September 24, 2018, which were first exercisable on March 24, 2019 and expire on March 24, 2024.

The intrinsic value of equity-classified common stock warrants outstanding at December 31, 2018 was zero.

On January 30, 2018, the Company issued warrants to purchase up to an aggregate of 1,095,153 shares of its common stock, which had an exercise price of $15.00 per share, subject to down round adjustment, are exercisable immediately and expire five years from the date of issuance. As a result of the down round adjustment feature of these warrants, these warrants have a current exercise price of $3.16 per share as of December 31, 2018.

Net Loss per Common Share

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Net Loss per Common Share

12. Net Loss per Common Share

Basic and diluted net loss per common share is determined by dividing net loss applicable to common shareholders by the weighted-average common shares outstanding during the period. Because there is a net loss attributable to common shareholders for the years ended December 31, 2017 and 2018, the outstanding RSUs, warrants, and common stock options have been excluded from the calculation of diluted loss per common share because their effect would be anti-dilutive. Therefore, the weighted-average shares used to calculate both basic and diluted loss per share are the same.

The following potentially dilutive securities have been excluded from the computations of diluted weighted-average shares outstanding for the periods presented, as they would be anti-dilutive:

	For the year ended
	December 31,
	2017		2018
Preferred warrants outstanding (number of common stock equivalents)		17		17
Common warrants outstanding		288,196		4,694,927
RSUs outstanding		12,030		360
Convertible preferred stock outstanding (number of common stock equivalents)		—		976,157
Common options outstanding		81,643		195,820
Total anti-dilutive common share equivalents		381,886		5,867,281

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

14. Income Taxes

On December 22, 2017, the President of the United States signed into law new legislation, or the Act, that significantly revises the Internal Revenue Code of 1986, as amended, or the Code. The Act amends the Code to reduce tax rates and modify policies, credits, and deductions for individuals and businesses. For businesses, the Act reduces the corporate tax rate from a maximum of 35% to a flat 21% rate. The rate reduction was effective on January 1, 2018. As a result of the rate reduction, the Company has reduced the deferred tax asset balance as of December 31, 2017 by approximately $2.6 million. Due to the Company's full valuation allowance position, the Company has also reduced the valuation allowance by the same amount. Due to uncertainties which currently exist in the interpretation of the provisions of the Act regarding Code Section 162(m), the Company has not evaluated the potential impacts of Code Section 162(m) as amended by the Act on its financial statements.

On December 22, 2017, the President of the United States signed into law the Tax Cuts and Jobs Act which, among a broad range of tax reform measures, reduced the U.S. corporate tax rate from 35% to a flat 21% effective January 1, 2018. The reduction in the U.S. corporate tax rate required the Company to remeasure the federal portion of deferred tax assets and liabilities at December 31, 2017 to the enacted tax rate expected to apply when the temporary differences are to be realized. The Company provisionally recorded $2.6 million of expense related, offset by a full valuation allowance, for the remeasurement of its deferred tax assets and liabilities. As of December 31, 2018, the Company completed its accounting for the tax effects of the enactment of the 2017 Act which resulted in immaterial adjustments to provisional estimates, offset by a full valuation allowance.

For the years ended December 31, 2017 and 2018, the provision for income taxes was calculated as follows:

	For the year ended December 31,
	2017		2018
Current:
Federal	$	—	$	—
State		7,624		1,886
Total		7,624		1,886
Deferred
Federal		—		—
State		—		—
Total		—		—
Provision for income tax	$	7,624	$	1,886

The following table reconciles income taxes computed at the federal statutory rate and the Company’s provision for income taxes:

	For the year ended December 31,
	2017			2018
Income tax at statutory rate	$	(7,346,079	)	$	(5,159,881	)
Change in federal tax rate		2,621,803			—
State liability		(411,853	)		(670,015	)
Permanent items		214,313			118,959
Stock compensation		72,696			11,128
Nondeductible interest		15,568			—
Expiration of net operating losses		922,307			—
Research and development credit		(200,379	)		(272,314	)
State rate change		(18,026	)		(132,855	)
Estimated section 382 limitation		1,491,942			—
Return to provision		365,263			8,386
Other		488,264			19,420
Valuation allowance		1,791,805			6,079,058
Provision for income tax	$	7,624		$	1,886

Deferred income taxes are provided for temporary differences in recognizing certain income and expense items for financial and tax reporting purposes. The deferred tax assets consisted primarily of the income tax benefits from estimated net operating loss carryforwards, deferred rent, and estimated research and development credits. Valuation allowances have been recorded to fully offset deferred tax assets at December 31, 2017 and 2018, as it is more likely than not that the assets will not be utilized.

At December 31, 2018, the Company had estimated federal net operating loss carryforwards of approximately $13.6 million expiring beginning in 2035 and total estimated state net operating loss carryforwards of approximately $24.7 million expiring beginning in 2023. The Company has additional federal net operating losses of $23.6 million generated after 2017, which carry over indefinitely and may generally be used to offset up to 80% of future taxable income. Additionally, at December 31, 2018, the Company had estimated research and development credits of approximately $160,000 and $3,543,000 for federal and California purposes, respectively. The estimated federal research and development tax credits will begin to expire in 2035. The California research and development tax credits do not expire.

For the years ended December 31, 2017 and 2018, the Company has evaluated the various tax positions reflected in its income tax returns for both federal and state jurisdictions, to determine if the Company has any uncertain tax positions on the historical tax returns. The Company recognizes the impact of an uncertain tax position on an income tax return at the largest amount that the relevant taxing authority is more-likely-than not to sustain upon audit. The Company does not recognize uncertain income tax positions if they have less than 50 percent likelihood of being sustained. Based on this assessment, the Company believes there are no tax positions for which a liability for unrecognized tax benefits should be recorded as of December 31, 2017 or 2018. The Company is subject to U.S. federal income tax as well as income tax in multiple state jurisdictions. With few exceptions, the Company is no longer subject to U.S. federal income tax examinations for 2015 and before, state and local income tax examinations 2014 and before. However, to the extent allowed by law, the tax authorities may have the right to examine prior periods where net operating losses were generated and carried forward and make adjustments up to the amount of the net operating loss carry forward amount. The Company’s policy is to recognize interest and penalties related to income tax matters in income tax expense. Due to the existence of the valuation allowance, future changes in unrecognized tax benefits will not impact the Company’s effective tax rate. The Company is currently not under examination by any taxing authorities and does not believe its unrecognized tax benefits will significantly change in the next twelve months.

The tax effects of carryforwards and other temporary differences that give rise to deferred tax assets consist of the following:

	For the year ended December 31,
	2017			2018
Estimated net operating loss carryforward	$	3,699,532		$	9,229,174
Estimated research and development credits		2,686,665			2,958,710
Accruals and other		2,560,419			2,864,028
Deferred rent		90,866			64,628
		9,037,482			15,116,540
Less valuation allowance		(9,037,482	)		(15,116,540	)
Net deferred tax assets	$	—		$	—

Utilization of the estimated domestic net operating loss and research and development credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations that may have occurred or that could occur in the future, as required by Section 382 and 383 of the Code, as well as similar state provisions. These ownership changes may limit the amount of estimated net operating loss and research and development credit carryforwards that can be utilized annually to offset future taxable income and tax, respectively. In general, an “ownership change” as defined by Section 382 of the Code results from a transaction or series of transactions over a three-year period resulting in an ownership change of more than 50 percentage points of the outstanding stock of a company by certain stockholders. Since the Company’s formation, the Company has raised capital through the issuance of capital stock on several occasions which on its own or combined with the purchasing stockholders’ subsequent disposition of those shares, likely resulted in such an ownership change, or could result in an ownership change in the future.

Upon the occurrence of an ownership change under Section 382 of the Code as outlined above, utilization of the estimated net operating loss and research and development credit carryforwards are subject to an annual limitation under Section 382, which is determined by first multiplying the value of the Company’s stock at the time of the ownership change by the applicable long-term, tax-exempt rate, which could be subject to additional adjustments, as required. Any limitation may result in expiration of a portion of the estimated net operating loss or research and development credit carryforwards before utilization. The Company has not yet completed an analysis to determine whether an ownership change has occurred, however, the Company believes ownership changes likely occurred in each year from 2015 through 2018. As a result, the Company has estimated that the use of its net operating loss is limited and has disclosed in the table above only the amounts it estimates could be used in the future, which remain fully offset by a valuation allowance to reduce the net asset to zero.

Related Party Transactions

12 Months Ended

Dec. 31, 2018

Related Party Transactions

15. Related Party Transactions

A member of the Company’s management is the controlling person of Aegea Biotechnologies, Inc., or Aegea. On September 2, 2012, the Company entered into an Assignment and Exclusive Cross-License Agreement, or the Cross-License Agreement, with Aegea. The Company received payments totaling approximately $15,000 and $19,000 during the years ended December 31, 2017 and 2018, respectively, from Aegea as reimbursements for shared patent costs under the Cross-License Agreement.

Pursuant to a sublease agreement dated March 30, 2015, the Company subleased 9,849 square feet, plus free use of an additional area, of its San Diego facility to an entity affiliated with the Company’s non-executive Chairman for $12,804 per month, with a refundable security deposit of $12,804 received from the subtenant. The initial term of the sublease expired on July 31, 2015 and was subject to renewal on a month-to-month basis thereafter. On February 1, 2017, the Company received notice from the subtenant terminating the sublease effective March 31, 2017. During the year ended December 31, 2017, the total amount of the $12,804 security deposit previously received from the subtenant was applied against approximately $16,000 in additional rents owed as a result of the subtenant continuing to occupy the subleased areas beyond March 31, 2017, and the balance of approximately $3,200 due to the Company was waived. A total of approximately $51,000 in rental income was recorded to other income/(expense) in the Company’s statement of operations and comprehensive loss during the year ended December 31, 2017. There was no income associated with this arrangement in 2018.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

16. Commitments and Contingencies

Operating Leases

The Company leases office, laboratory, and warehouse space at its San Diego, California facility under a non-cancelable operating lease. The initial lease was for an eight-year term expiring in 2012. In November 2011, the Company extended the lease term through October 31, 2018 and expanded the original premises by 9,849 square feet. Under the amended lease, the landlord delivered the expanded premises in May 2013. In September 2013, the Company extended the lease term through July 31, 2020. The Company records rent expense on a straight-line basis over the life of the lease and records the excess of expense over the amounts paid as deferred rent. During each of the years ended December 31, 2017 and 2018, total rent expense recorded in the Company’s statements of operations and comprehensive loss was approximately $1,272,000.

The future minimum lease payments under the amended lease agreement as December 31, 2018 are as follows:

2019	$	1,430,366
2020		855,136
Thereafter		—
Total	$	2,285,502

Purchase Commitment

In February 2016, the Company signed a firm, non-cancelable, and unconditional commitment in an aggregate amount of $1,062,500 with a vendor to purchase certain inventory items, payable in minimum quarterly amounts of $62,500 through May 2020. At December 31, 2018, approximately $341,000 remained outstanding under this purchase commitment.

Financed Equipment Maintenance and Sales Tax Obligations

During the years ended December 31, 2017 and 2018, total expense recorded in the Company’s statement of operations and comprehensive loss for sales tax and maintenance obligations associated with equipment financing arrangements was approximately $79,000 and $101,000, respectively. At December 31, 2018, approximately $69,000 of such sales tax and maintenance obligations incurred but not paid were recorded in accrued other liabilities in the Company’s balance sheet (see Note 6). Future payments totaling approximately $322,000 for sales tax and maintenance obligations associated with financed equipment were due under equipment financing arrangements at December 31, 2018, which will be expensed as incurred (see Note 8).

Legal Proceedings

In the normal course of business, the Company may be involved in legal proceedings or threatened legal proceedings. The Company is not party to any legal proceedings or aware of any threatened legal proceedings which are expected to have a material adverse effect on its financial condition, results of operations or liquidity.

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data (Unaudited)

17. Selected Quarterly Financial Data (Unaudited)

The following is selected quarterly financial data as of and for the periods ending:

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
December 31, 2017
Balance sheet data:
Cash	$	14,042,388		$	10,000,155		$	5,879,025		$	2,146,611
Total assets		17,933,413			14,653,193			11,120,215			7,378,906
Total non-current liabilities		2,062,544			1,561,520			1,255,939			1,421,527
Total shareholders’ equity		10,418,069			7,342,257			4,026,079			1,296,034
Statement of operations and comprehensive loss data:
Net revenues	$	1,683,065		$	1,278,961		$	1,111,411		$	995,226
Cost of revenues		2,129,454			2,368,705			2,487,054			2,359,909
Research and development expenses		757,258			841,991			856,698			908,800
General and administrative expenses		1,906,635			1,798,026			1,834,771			1,650,097
Sales and marketing expenses		1,278,311			1,746,867			1,675,852			1,642,941
Loss from operations		(4,388,593	)		(5,476,628	)		(5,742,964	)		(5,566,521	)
Net loss	$	(4,432,707	)	$	(5,693,151	)	$	(5,821,306	)	$	(5,666,573	)
Net loss per common share:¹
Basic	$	(6.27	)	$	(6.32	)	$	(5.85	)	$	(5.36	)

Diluted	$	(6.27	)	$	(6.32	)	$	(5.85	)	$	(5.36	)

Weighted-average shares outstanding used in computing net loss per share attributable to common shareholders:
Basic		707,389			901,007			995,254			1,058,055

Diluted		707,389			901,007			995,254			1,058,055

¹	Basic and diluted net loss per common share are computed independently for each of the components and quarters presented. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted net loss per common share.

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
December 31, 2018
Balance sheet data:
Cash	$	9,272,420		$	2,569,111		$	8,956,200		$	3,423,373
Total assets		14,747,827			8,291,310			14,551,892			8,750,303
Total non-current liabilities		1,357,193			1,258,261			1,174,397			1,098,137
Total shareholders’ equity		8,507,714			2,527,568			8,938,408			3,042,519
Statement of operations and comprehensive loss data:
Net revenues	$	806,943		$	822,238		$	761,591		$	859,526
Cost of revenues		2,434,886			2,699,671			2,481,916			2,435,262
Research and development expenses		1,070,584			1,019,285			1,089,746			1,288,957
General and administrative expenses		1,938,664			1,708,970			1,793,720			1,632,670
Sales and marketing expenses		1,636,542			1,433,174			1,404,192			1,440,798
Loss from operations		(6,273,733	)		(6,038,862	)		(6,007,983	)		(5,938,161	)
Net loss	$	(6,356,404	)	$	(6,153,101	)	$	(6,047,784	)	$	(6,014,312	)
Deemed dividend related to warrants down round provision		—			—			(636,370	)		—
Net loss attributable to common shareholders	$	(6,356,404	)	$	(6,153,101	)	$	(6,684,154	)	$	(6,014,312	)
Net loss per common share:¹
Basic	$	(3.33	)	$	(2.70	)	$	(2.42	)	$	(1.43	)

Diluted	$	(3.33	)	$	(2.70	)	$	(2.42	)	$	(1.43	)

Weighted-average shares outstanding used in computing net loss per share attributable to common shareholders:
Basic		1,911,282			2,280,115			2,767,440			4,209,221

Diluted		1,911,282			2,280,115			2,759,614			4,209,221

¹	Basic and diluted net loss per common share are computed independently for each of the components and quarters presented. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted net loss per common share.

Subsequent Events

12 Months Ended

Dec. 31, 2018

Subsequent Events [Abstract]

Subsequent Events

18. Subsequent Events

On January 18, 2019, the Company completed an offering of 990,000 shares of the Company’s common stock. The shares were sold at a purchase price of $2.25 per share and the net proceeds to the Company from this offering were approximately $2.0 million, after deducting expenses related to the offering including dealer-manager fees and expenses.

On February 12, 2019, the Company received net cash proceeds of approximately $6.8 million as a result of the closing of a follow-on public offering of 6,250,000 shares of its common stock and warrants to purchase up to an aggregate of 6,250,000 shares of its common stock at a combined offering price of $1.20 per unit. All warrants sold in this offering have an exercise price of $1.20 per share, are exercisable immediately and expire five years from the date of issuance. In addition, the Company sold warrants to purchase up to an aggregate of 937,500 shares of the Company’s common stock in connection with the partial exercise of the over-allotment option granted to the underwriters. Subsequent to the closing of this offering, no additional cash proceeds have been received from the exercise of warrants sold in this offering. On March 11, 2019, the underwriters exercised their overallotment option for 538,867 shares of the Company’s common stock related to the February 12, 2019 follow-on offering, purchasing shares at $1.20 for net cash proceeds of approximately $601,000.

Pursuant to the down round adjustment feature of the January 2018 warrants, the exercise price of these warrants was adjusted to the $1.20 price per share offering price in the February 2019 financing transaction.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

The Company and Business Activities

1. The Company and Business Activities

Basis of Presentation

Going Concern

Use of Estimates

Revenue Recognition and Accounts Receivable

Contracts

•

Approval of a contract is established via the order and accession, which are submitted by the patient’s physician.

•

Performance Obligations

Transaction Price

Allocate Transaction Price

Point-in-time Recognition

Contract Balances

Practical Expedients

The Company does not adjust the transaction price for the effects of a significant financing component, as at contract inception, the Company expects the collection cycle to be one year or less.

The Company expenses sales commissions when incurred because the amortization period is one year or less, which are recorded within sales and marketing expenses.

Disaggregation of Revenue and Concentration of Risk

The composition of the Company’s net revenues recognized during the years ended December 31, 2017 and 2018, disaggregated by source and nature, are as follows:


	For the year ended December 31,
	2017		2018
Net revenues from contracted payers*	$	2,074,596	$	1,348,383
Net revenues from non-contracted payers		2,721,717		1,703,179
Development services revenues		272,350		198,736
Total net revenues	$	5,068,663	$	3,250,298

*Includes Medicare and Medicare Advantage, as reimbursement amounts are fixed and miscellaneous income from CEE-Sure blood collection tubes.


	For the year ended December 31,
	2017		2018
Net commercial revenues recognized upon delivery	$	3,570,337	$	3,051,562
Development services revenues recognized upon delivery		272,350		198,736
Commercial revenues recognized upon cash collection		1,225,976		—
Total net revenues	$	5,068,663	$	3,250,298

The composition of the Company’s gross and net revenues recognized during the years ended December 31, 2017 and 2018 is as follows:

	For the year ended December 31,
	2017			2018
Commercial revenues recognized upon delivery	$	15,685,069		$	12,505,149
Development services revenues recognized upon delivery		272,350			198,736
Commercial revenues recognized upon cash collection		1,225,976			—
Total gross revenues		17,183,395			12,703,885
Provisions for contractual discounts		(5,805,787	)		(3,937,993	)
Provisions for aged non-patient receivables		(735,709	)		(326,137	)
Provisions for estimated patient receivables		(169,479	)		(66,470	)
Provisions for other payer-specific sales allowances		(5,403,757	)		(5,122,987	)
Net revenues	$	5,068,663		$	3,250,298

A summary of activity in the Company’s gross and net accounts receivable balances, as well as corresponding reserves, during the year ended December 31, 2018 is as follows:

	Balance at			Amounts			Settlements			Balance at
	December 31,			Recognized			Upon			December 31,
	2017			Upon Delivery			Adjudication			2018
Accounts receivable, gross	$	6,937,063		$	12,835,371		$	(11,889,832	)	$	7,882,602
Reserve for contractual discounts		(1,974,849	)		(3,214,615	)		3,011,989			(2,177,475	)
Reserve for aged non-patient receivables		(452,088	)		(994,542	)		880,682			(565,948	)
Reserve for estimated patient receivables		(88,120	)		(135,955	)		208,598			(15,477	)
Reserve for other payer-specific sales allowances		(3,228,580	)		(5,239,961	)		4,919,164			(3,549,377	)
Accounts receivable, net	$	1,193,426		$	3,250,298		$	(2,869,399	)	$	1,574,325

Cash

Fair Value Measurements

Concentration of Risk

Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of temporary cash investments.

Concentrations of credit risk with respect to revenues are primarily limited to geographies to which the Company provides a significant volume of its services, and to specific third-party payers of the Company’s services such as Medicare, insurance companies, and other third-party payers. The Company’s client base consists of a large number of geographically dispersed clients diversified across various customer types.

	For the year ended December 31,
	2017			2018
Medicare and Medicare Advantage		39	%		39	%
Blue Cross Blue Shield		19	%		11	%
United Healthcare		12	%		17	%

	For the year ended December 31,
	2017			2018
Blue Cross Blue Shield		27	%		22	%
Medicare and Medicare Advantage		21	%		17	%
United Healthcare		15	%		15	%

The Company operates in one reportable business segment and historically has derived most revenues only from within the United States.

Inventories

Fixed Assets

Stock-based Compensation

Research and Development

Income Taxes

Recent Accounting Pronouncements

Stock Options [Member]

Fair Value Measurements

Restricted Stock [Member]

Fair Value Measurements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Composition of Net Revenues Recognized Disaggregated by Source and Nature

The composition of the Company’s net revenues recognized during the years ended December 31, 2017 and 2018, disaggregated by source and nature, are as follows:


	For the year ended December 31,
	2017		2018
Net revenues from contracted payers*	$	2,074,596	$	1,348,383
Net revenues from non-contracted payers		2,721,717		1,703,179
Development services revenues		272,350		198,736
Total net revenues	$	5,068,663	$	3,250,298

*Includes Medicare and Medicare Advantage, as reimbursement amounts are fixed and miscellaneous income from CEE-Sure blood collection tubes.


	For the year ended December 31,
	2017		2018
Net commercial revenues recognized upon delivery	$	3,570,337	$	3,051,562
Development services revenues recognized upon delivery		272,350		198,736
Commercial revenues recognized upon cash collection		1,225,976		—
Total net revenues	$	5,068,663	$	3,250,298

Composition of Gross and Net Revenues Recognized

The composition of the Company’s gross and net revenues recognized during the years ended December 31, 2017 and 2018 is as follows:

	For the year ended December 31,
	2017			2018
Commercial revenues recognized upon delivery	$	15,685,069		$	12,505,149
Development services revenues recognized upon delivery		272,350			198,736
Commercial revenues recognized upon cash collection		1,225,976			—
Total gross revenues		17,183,395			12,703,885
Provisions for contractual discounts		(5,805,787	)		(3,937,993	)
Provisions for aged non-patient receivables		(735,709	)		(326,137	)
Provisions for estimated patient receivables		(169,479	)		(66,470	)
Provisions for other payer-specific sales allowances		(5,403,757	)		(5,122,987	)
Net revenues	$	5,068,663		$	3,250,298

Summary of Activity in Gross and Net Accounts Receivable Balances and Reserves

A summary of activity in the Company’s gross and net accounts receivable balances, as well as corresponding reserves, during the year ended December 31, 2018 is as follows:

	Balance at			Amounts			Settlements			Balance at
	December 31,			Recognized			Upon			December 31,
	2017			Upon Delivery			Adjudication			2018
Accounts receivable, gross	$	6,937,063		$	12,835,371		$	(11,889,832	)	$	7,882,602
Reserve for contractual discounts		(1,974,849	)		(3,214,615	)		3,011,989			(2,177,475	)
Reserve for aged non-patient receivables		(452,088	)		(994,542	)		880,682			(565,948	)
Reserve for estimated patient receivables		(88,120	)		(135,955	)		208,598			(15,477	)
Reserve for other payer-specific sales allowances		(3,228,580	)		(5,239,961	)		4,919,164			(3,549,377	)
Accounts receivable, net	$	1,193,426		$	3,250,298		$	(2,869,399	)	$	1,574,325

Summary of Third-Party Payers That Represent More Than 10% of Total Net Revenues and Total Net Accounts Receivable and Their Related Percentage

	For the year ended December 31,
	2017			2018
Medicare and Medicare Advantage		39	%		39	%
Blue Cross Blue Shield		19	%		11	%
United Healthcare		12	%		17	%

	For the year ended December 31,
	2017			2018
Blue Cross Blue Shield		27	%		22	%
Medicare and Medicare Advantage		21	%		17	%
United Healthcare		15	%		15	%

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Assumptions Used for Determining Fair Values of Common Stock Warrants

Stock price	$	63.90
Exercise price	$	75.00
Expected dividend yield		0.00	%
Discount rate-bond equivalent yield		1.93	%
Expected life (in years)		5.00
Expected volatility		80.0	%

Stock price	$	41.70
Exercise price	$	45.00
Expected dividend yield		0.00	%
Discount rate-bond equivalent yield		1.81	%
Expected life (in years)		5.00
Expected volatility		100.0	%

Stock price	$	22.20
Exercise price	$	25.50
Expected dividend yield		0.00	%
Discount rate-bond equivalent yield		2.09	%
Expected life (in years)		4.50
Expected volatility		100.0	%

The fair value of the warrants was at issuance estimated using a Monte Carlo simulation valuation model using Geometric Brownian Motion, incorporating anticipated future financing events, with the following assumptions:

Beginning stock price	$	10.17
Exercise price	$	15.00
Expected dividend yield		0.00	%
Discount rate-bond equivalent yield		2.48	%
Expected life (in years)		5.00
Expected volatility		99.00	%

The fair value of the warrants was estimated using a Black-Scholes model, incorporating the following assumptions:

Beginning stock price	$	3.89
Exercise price	$	4.53
Expected dividend yield		0.00	%
Discount rate-bond equivalent yield		2.75	%
Expected life (in years)		5.00
Expected volatility		128.69	%

The fair value of the warrants was estimated using a Black-Scholes model, incorporating the following assumptions:

Beginning stock price	$	2.92
Exercise price	$	3.16
Expected dividend yield		0.00	%
Discount rate-bond equivalent yield		2.77	%
Expected life (in years)		5.50
Expected volatility		130.7	%

Balance Sheet Details (Tables)

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Schedule of Fixed Assets and Accrued Liabilities

The following provides certain balance sheet details:

	December 31,			December 31,
	2017			2018
Fixed Assets
Machinery and equipment	$	2,841,388		$	2,818,583
Furniture and office equipment		147,976			157,391
Computer equipment and software		1,637,034			1,437,408
Leasehold improvements		553,529			570,173
Financed equipment		2,294,762			2,573,955
Construction in process		2,975			116,640
		7,477,664			7,674,150
Less accumulated depreciation and amortization		(4,354,097	)		(4,934,728	)
Total fixed assets, net	$	3,123,567		$	2,739,422
Accrued Liabilities
Accrued interest	$	326,602		$	-
Accrued payroll		224,813			255,426
Accrued vacation		474,953			535,682
Accrued bonuses		375,000			712,574
Accrued sales commissions		104,509			62,767
Current portion of deferred rent		116,681			158,342
Accrued other		129,805			203,602
Total accrued liabilities	$	1,752,363		$	1,928,393

Equipment Financings (Tables)

12 Months Ended

Dec. 31, 2018

Capital Lease Obligations [Abstract]

Schedule of Remaining Future Minimum Lease Payments for Financed Equipment Obligations

			Maintenance
	Minimum		and Sales Tax
	Lease		Obligation
	Payments		Payments
2019	$	670,896	$	91,285
2020		551,610		72,635
2021		305,006		51,473
2022		264,600		60,832
Thereafter		310,932		45,710
Total payments		2,103,044		321,935
Less amount representing interest		476,493		-
Present value of payments	$	1,626,551	$	321,935

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Assumptions Used for Determining Fair Value of Stock Options Under Black-Scholes Pricing Model

The assumptions used in the Black-Scholes pricing model for options granted during the years ended December 31, 2017 and 2018 are as follows:

	2017	2018
Stock and exercise prices	$20.82 - $63.90	$0.86 - $6.00
Expected dividend yield	0.00%	0.00%
Discount rate-bond equivalent yield	1.79% – 2.27%	2.50% - 3.02%
Expected life (in years)	5.12 – 6.09	4.00 - 5.96
Expected volatility	70.0% – 90.0%	100% - 120%

Summary of Stock Option Activity

A summary of stock option activity for the years ended December 31, 2017 and 2018 is as follows:

	Number of Shares			Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Term in Years
Outstanding at December 31, 2016		29,888		$	264.00		8.5
Granted		58,501		$	44.70
Exercised		—			—
Cancelled/forfeited/expired		(6,746	)	$	143.10
Outstanding at December 31, 2017		81,643		$	113.68		8.8
Granted		142,587		$	2.20
Exercised		—			—
Cancelled/forfeited/expired		(28,410	)	$	57.96
Outstanding at December 31, 2018		195,820		$	41.41		9.2
Vested and unvested expected to vest, December 31, 2018		183,136		$	44.02		9.1

Summary of RSU Activity

A summary of RSU activity during 2017 and 2018 is as follows:

	Number of Shares			Weighted Average Grant Date Fair Value
Outstanding at December 31, 2016		5,808		$	80.40
Granted		11,666		$	45.00
Vested and issued		(5,194	)	$	58.80
Forfeited		(250	)	$	63.60
Outstanding at December 31, 2017		12,030		$	56.10
Granted		—		$	—
Vested and issued		(5,835	)	$	45.00
Forfeited		(5,835	)	$	45.00
Outstanding at December 31, 2018		360		$	415.80
Vested and unvested expected to vest, December 31, 2018		360		$	415.80

Effects of Stock-Based Compensation Related to Equity Awards to Employees and Nonemployees on Statement of Operations

The following table presents the effects of stock-based compensation related to equity awards to employees and nonemployees on the statement of operations during the periods presented:

	Years Ended December 31,
	2017		2018
Stock Options
Cost of revenues	$	142,400	$	46,708
Research and development expenses		143,300		133,525
General and administrative expenses		575,741		300,433
Sales and marketing expenses		68,381		78,321
Total expenses related to stock options		929,822		558,987
RSUs
Cost of revenues		48,745		(18,802	)
Research and development expenses		55,941		13,576
General and administrative expenses		160,937		54,302
Sales and marketing expenses		52,036		15,349
Total stock-based compensation	$	1,247,481	$	623,412

Common Stock Warrants Outstanding (Tables)

12 Months Ended

Dec. 31, 2018

Equity Classified Warrants [Abstract]

Summary of Equity-Classified Common Stock Warrant Activity, for Warrants Other than Underlying Unexercised Overallotment Option Warrants

A summary of equity-classified common stock warrant activity, for warrants other than those underlying unexercised overallotment option warrants, during 2017 and 2018 is as follows:

							Average
					Weighted		Remaining
	Number of				Average Exercise		Contractual
	Shares				Price Per Share		Term in Years
Outstanding at December 31, 2016		387,395		$		57.90		4.6
Issued		128,029		$		60.62
Exercised		(227,228	)	$		33.00
Expired		—		$		—
Outstanding at December 31, 2017		288,196		$		78.86		4.0
Issued		4,526,661		$		3.85
Exercised		(120,000	)	$		0.01
Expired		—		$		—
Outstanding at December 31, 2018		4,694,927		$		8.55		4.4

Net Loss per Common Share (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Schedule of Anti-Dilutive Securities Excluded from Computations of Diluted Weighted-Average Shares

The following potentially dilutive securities have been excluded from the computations of diluted weighted-average shares outstanding for the periods presented, as they would be anti-dilutive:

	For the year ended
	December 31,
	2017		2018
Preferred warrants outstanding (number of common stock equivalents)		17		17
Common warrants outstanding		288,196		4,694,927
RSUs outstanding		12,030		360
Convertible preferred stock outstanding (number of common stock equivalents)		—		976,157
Common options outstanding		81,643		195,820
Total anti-dilutive common share equivalents		381,886		5,867,281

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of Provision for Income Taxes

For the years ended December 31, 2017 and 2018, the provision for income taxes was calculated as follows:

	For the year ended December 31,
	2017		2018
Current:
Federal	$	—	$	—
State		7,624		1,886
Total		7,624		1,886
Deferred
Federal		—		—
State		—		—
Total		—		—
Provision for income tax	$	7,624	$	1,886

Reconciles of Income Taxes Computed at Federal Statutory Rate and Provision for Income Taxes

The following table reconciles income taxes computed at the federal statutory rate and the Company’s provision for income taxes:

	For the year ended December 31,
	2017			2018
Income tax at statutory rate	$	(7,346,079	)	$	(5,159,881	)
Change in federal tax rate		2,621,803			—
State liability		(411,853	)		(670,015	)
Permanent items		214,313			118,959
Stock compensation		72,696			11,128
Nondeductible interest		15,568			—
Expiration of net operating losses		922,307			—
Research and development credit		(200,379	)		(272,314	)
State rate change		(18,026	)		(132,855	)
Estimated section 382 limitation		1,491,942			—
Return to provision		365,263			8,386
Other		488,264			19,420
Valuation allowance		1,791,805			6,079,058
Provision for income tax	$	7,624		$	1,886

Summary of Deferred Tax Assets

The tax effects of carryforwards and other temporary differences that give rise to deferred tax assets consist of the following:

	For the year ended December 31,
	2017			2018
Estimated net operating loss carryforward	$	3,699,532		$	9,229,174
Estimated research and development credits		2,686,665			2,958,710
Accruals and other		2,560,419			2,864,028
Deferred rent		90,866			64,628
		9,037,482			15,116,540
Less valuation allowance		(9,037,482	)		(15,116,540	)
Net deferred tax assets	$	—		$	—

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Schedule of Future Minimum Lease Payments

The future minimum lease payments under the amended lease agreement as December 31, 2018 are as follows:

2019	$	1,430,366
2020		855,136
Thereafter		—
Total	$	2,285,502

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Summary of Selected Quarterly Financial Data

The following is selected quarterly financial data as of and for the periods ending:

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
December 31, 2017
Balance sheet data:
Cash	$	14,042,388		$	10,000,155		$	5,879,025		$	2,146,611
Total assets		17,933,413			14,653,193			11,120,215			7,378,906
Total non-current liabilities		2,062,544			1,561,520			1,255,939			1,421,527
Total shareholders’ equity		10,418,069			7,342,257			4,026,079			1,296,034
Statement of operations and comprehensive loss data:
Net revenues	$	1,683,065		$	1,278,961		$	1,111,411		$	995,226
Cost of revenues		2,129,454			2,368,705			2,487,054			2,359,909
Research and development expenses		757,258			841,991			856,698			908,800
General and administrative expenses		1,906,635			1,798,026			1,834,771			1,650,097
Sales and marketing expenses		1,278,311			1,746,867			1,675,852			1,642,941
Loss from operations		(4,388,593	)		(5,476,628	)		(5,742,964	)		(5,566,521	)
Net loss	$	(4,432,707	)	$	(5,693,151	)	$	(5,821,306	)	$	(5,666,573	)
Net loss per common share:¹
Basic	$	(6.27	)	$	(6.32	)	$	(5.85	)	$	(5.36	)

Diluted	$	(6.27	)	$	(6.32	)	$	(5.85	)	$	(5.36	)

Weighted-average shares outstanding used in computing net loss per share attributable to common shareholders:
Basic		707,389			901,007			995,254			1,058,055

Diluted		707,389			901,007			995,254			1,058,055

¹	Basic and diluted net loss per common share are computed independently for each of the components and quarters presented. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted net loss per common share.

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
December 31, 2018
Balance sheet data:
Cash	$	9,272,420		$	2,569,111		$	8,956,200		$	3,423,373
Total assets		14,747,827			8,291,310			14,551,892			8,750,303
Total non-current liabilities		1,357,193			1,258,261			1,174,397			1,098,137
Total shareholders’ equity		8,507,714			2,527,568			8,938,408			3,042,519
Statement of operations and comprehensive loss data:
Net revenues	$	806,943		$	822,238		$	761,591		$	859,526
Cost of revenues		2,434,886			2,699,671			2,481,916			2,435,262
Research and development expenses		1,070,584			1,019,285			1,089,746			1,288,957
General and administrative expenses		1,938,664			1,708,970			1,793,720			1,632,670
Sales and marketing expenses		1,636,542			1,433,174			1,404,192			1,440,798
Loss from operations		(6,273,733	)		(6,038,862	)		(6,007,983	)		(5,938,161	)
Net loss	$	(6,356,404	)	$	(6,153,101	)	$	(6,047,784	)	$	(6,014,312	)
Deemed dividend related to warrants down round provision		—			—			(636,370	)		—
Net loss attributable to common shareholders	$	(6,356,404	)	$	(6,153,101	)	$	(6,684,154	)	$	(6,014,312	)
Net loss per common share:¹
Basic	$	(3.33	)	$	(2.70	)	$	(2.42	)	$	(1.43	)

Diluted	$	(3.33	)	$	(2.70	)	$	(2.42	)	$	(1.43	)

Weighted-average shares outstanding used in computing net loss per share attributable to common shareholders:
Basic		1,911,282			2,280,115			2,767,440			4,209,221

Diluted		1,911,282			2,280,115			2,759,614			4,209,221

¹	Basic and diluted net loss per common share are computed independently for each of the components and quarters presented. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted net loss per common share.

Liquidity and Going Concern Uncertainty- Additional Information (Detail) - USD ($)															1 Months Ended			3 Months Ended								12 Months Ended
	Mar. 19, 2019	Mar. 11, 2019	Feb. 12, 2019	Jan. 18, 2019	Nov. 28, 2018	Sep. 20, 2018	Aug. 13, 2018	Jan. 31, 2018	Jan. 30, 2018	Dec. 08, 2017	Aug. 11, 2017	Aug. 09, 2017	Mar. 31, 2017	May 04, 2016	May 31, 2018	Feb. 29, 2016	May 31, 2015	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Liquidity And Managements Plans [Line Items]
Cash													$ 14,042,388					$ 3,423,373	$ 8,956,200	$ 2,569,111	$ 9,272,420	$ 2,146,611	$ 5,879,025	$ 10,000,155	$ 14,042,388	$ 3,423,373	$ 2,146,611	$ 4,609,332
Accumulated deficit																		(220,457,578)				(195,249,607)				(220,457,578)	(195,249,607)
Net loss																		(6,014,312)	$ (6,047,784)	$ (6,153,101)	$ (6,356,404)	(5,666,573)	$ (5,821,306)	$ (5,693,151)	$ (4,432,707)	(24,571,601)	(21,613,737)
Aggregate net interest-bearing indebtedness																		1,600,000				3,100,000				1,600,000	3,100,000
Aggregate net interest-bearing indebtedness due within one year																		642,000				2,000,000				642,000	2,000,000
Other non-interest bearing current liabilities																						$ 2,700,000					2,700,000
Unconditional purchase commitment aggregate amount																$ 1,062,500		$ 341,000								$ 341,000
Unconditional purchase commitment payment terms																										Quarterly
Unconditional purchase commitment period																										May 31, 2020
Minimum public float limit for offering															$ 75,000,000
Proceeds from issuance of common stock, net of issuance costs												$ 2,000,000
Proceeds from exercise of common stock warrants											$ 0															$ 1,200	$ 7,498,535
Exercisable warrant available price per share expiration period											2022-08
Shares issued in offering						642,438
Beginning stock price						$ 3.285			$ 13.50
Issuance of unregistered warrants to purchase shares of common stock						762,438	2,549,140			8,208		47,821	72,000												72,000
Exercise price of unregistered warrants							$ 4.53		$ 3.16	$ 25.50	$ 45.00	$ 45.00	$ 75.00					$ 3.16							$ 75.00	$ 3.16
Class of warrant or rights, expiration date										Dec. 05, 2022
Class of warrant or rights, first exercisable date										Jun. 05, 2018
Proceeds from issuance of common stock						$ 2,500,000	$ 11,600,000				$ 2,200,000
Aggregate units sold under right offering							11,587
Net proceeds from issuance of units, net of issuance expenses						$ 2,200,000	$ 10,100,000
Warrant exercisable for share of common stock							1
Class of warrant or rights, term							5 years		5 years
Subsequent Event [Member]
Liquidity And Managements Plans [Line Items]
Proceeds from issuance of common stock, net of issuance costs	$ 7,500,000			$ 2,000,000
Shares issued in offering	5,950,000			990,000
Beginning stock price	$ 1.37			$ 2.25
Exercise price of unregistered warrants	$ 1.25		$ 1.20
Warrant exercisable for share of common stock	1
Class of warrant or rights, term	5 years 6 months
Prefunded Warrants [Member]
Liquidity And Managements Plans [Line Items]
Proceeds from exercise of common stock warrants					$ 1,200
Exercise price of unregistered warrants						$ 3.275
Issuance of warrants to purchase shares of common stock						120,000
Change in exercise price of warrants						$ 0.01
Series A Preferred Stock [Member]
Liquidity And Managements Plans [Line Items]
Shares issued in offering							11,587
Warrants [Member]
Liquidity And Managements Plans [Line Items]
Exercise price of unregistered warrants									$ 15.00
Class of warrant or rights, expiration date																										Mar. 24, 2024
Class of warrant or rights, first exercisable date																										Mar. 24, 2019
Aggregate warrants sold under right offering							2,549,140
Class of warrant or rights, term									5 years
Roth Capital Partners, LLC, WestPark Capital and Chardan Capital [Member]
Liquidity And Managements Plans [Line Items]
Placement agent agreement, effective date													Mar. 28, 2017
Proceeds from issuance of common stock, net of issuance costs													$ 8,600,000
Proceeds from exercise of common stock warrants													$ 0
Shares issued in offering													144,000
Beginning stock price													$ 64.50												$ 64.50
Issuance of unregistered warrants to purchase shares of common stock													72,000												72,000
Exercise price of unregistered warrants													$ 75.00												$ 75.00
Class of warrant or rights, expiration date													Oct. 01, 2022
Dawson James Securities, Inc and WestPark Capital [Member]
Liquidity And Managements Plans [Line Items]
Placement agent agreement, effective date										Dec. 05, 2017
Proceeds from issuance of common stock, net of issuance costs										$ 2,900,000
Shares issued in offering										164,166
Beginning stock price										$ 20.40
Issuance of unregistered warrants to purchase shares of common stock										8,208
Exercise price of unregistered warrants										$ 25.50
Class of warrant or rights, expiration date										Dec. 05, 2022
Class of warrant or rights, first exercisable date										Jun. 05, 2018
Shelf Registration Statement [Member]
Liquidity And Managements Plans [Line Items]
Shelf registration statement expiration period															May 31, 2021		May 31, 2018
Minimum public float limit for offering															$ 75,000,000		$ 75,000,000
Placement agent agreement, effective date														Apr. 25, 2016
Securities purchase agreement, effective date														Apr. 29, 2016
Proceeds from issuance of common stock, net of issuance costs														$ 4,300,000
Proceeds from exercise of common stock warrants														0
Proceeds from gross exercise of common stock warrants outstanding														$ 4,500,000
Exercisable warrant available price per share														$ 117.00
Exercisable warrant available price per share expiration period														2021-05
Follow-on Public Offering [Member]
Liquidity And Managements Plans [Line Items]
Proceeds from issuance of common stock, net of issuance costs									$ 13,300,000
Proceeds from exercise of common stock warrants								$ 0	0
Proceeds from gross exercise of common stock warrants outstanding									$ 16,400,000
Exercisable warrant available price per share									$ 3.16
Exercisable warrant available price per share expiration period									2023-01
Beginning stock price									$ 13.50
Exercise price of unregistered warrants						$ 3.16	$ 4.53		$ 3.16
Class of warrant or rights, term						5 years	5 years		5 years
Follow-on Public Offering [Member] \| Subsequent Event [Member]
Liquidity And Managements Plans [Line Items]
Proceeds from issuance of common stock, net of issuance costs		$ 601,000	$ 6,800,000
Proceeds from exercise of common stock warrants			$ 0
Shares issued in offering			6,250,000
Beginning stock price		$ 1.20	$ 1.20
Exercise price of unregistered warrants			$ 1.20
Class of warrant or rights, term			5 years
Purchase of common stock by underwriters to cover overallotments, number of shares		538,867
Follow-on Public Offering [Member] \| Warrants [Member] \| Subsequent Event [Member]
Liquidity And Managements Plans [Line Items]
Shares issued in offering			6,250,000
Private Placement [Member]
Liquidity And Managements Plans [Line Items]
Exercise price of unregistered warrants						$ 3.16
Warrant exercisable for share of common stock						1
Class of warrant or rights, term						5 years
Over-allotment Option [Member] \| Subsequent Event [Member]
Liquidity And Managements Plans [Line Items]
Issuance of warrants to purchase shares of common stock			937,500
Minimum [Member]
Liquidity And Managements Plans [Line Items]
Unconditional purchase commitment, quarterly payment amount																$ 62,500
Maximum [Member]
Liquidity And Managements Plans [Line Items]
Issuance of unregistered warrants to purchase shares of common stock									1,095,153
Issuance of warrants to purchase shares of common stock									1,095,153
Maximum [Member] \| Prefunded Warrants [Member]
Liquidity And Managements Plans [Line Items]
Issuance of warrants to purchase shares of common stock						120,000
Maximum [Member] \| Warrants [Member]
Liquidity And Managements Plans [Line Items]
Issuance of warrants to purchase shares of common stock									1,095,153
Maximum [Member] \| Shelf Registration Statement [Member]
Liquidity And Managements Plans [Line Items]
Aggregate offering price															$ 50,000,000		$ 50,000,000
Maximum [Member] \| Follow-on Public Offering [Member]
Liquidity And Managements Plans [Line Items]
Issuance of warrants to purchase shares of common stock									1,095,153
Maximum [Member] \| Follow-on Public Offering [Member] \| Subsequent Event [Member]
Liquidity And Managements Plans [Line Items]
Issuance of warrants to purchase shares of common stock			6,250,000
Maximum [Member] \| Over-allotment Option [Member] \| Subsequent Event [Member]
Liquidity And Managements Plans [Line Items]
Issuance of warrants to purchase shares of common stock			937,500

Summary of Significant Accounting Policies - Additional Information (Detail)		3 Months Ended								12 Months Ended
	Jul. 06, 2018 shares	Dec. 31, 2018 USD ($) shares	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) shares	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) Segment shares	Dec. 31, 2017 USD ($) $ / shares shares
Summary Of Significant Accounting Policies [Line Items]
Stockholders equity reverse stock split ratio	0.03
Common stock, shares authorized \| shares	150,000,000	150,000,000				150,000,000				150,000,000	150,000,000
Description of reverse stock split	On July 6, 2018, the Company’s stockholders approved, and the Company filed, an amendment to the Company’s Certificate of Amendment of Certificate of Incorporation to effect a one-for-thirty reverse stock split of the Company’s outstanding common stock.
Nonrecurring net revenue recognized on accrual basis associated with cases delivered											$ 843,000
Increase (decrease) in net income (loss) per common share on nonrecurring net revenue \| $ / shares											$ (0.90)
Net revenue recorded in excess of commercial cash collections											$ 1,139,000
Increase decrease in net income (loss) per common share \| $ / shares											$ (1.20)
Number of reportable segments \| Segment										1
Number of suppliers										one supplier
Depreciation and amortization expense										$ 800,905	$ 575,717
Research and development expenses		$ 1,288,957	$ 1,089,746	$ 1,019,285	$ 1,070,584	$ 908,800	$ 856,698	$ 841,991	$ 757,258	4,468,572	3,364,747
Accrual for interest or penalties for income taxes		$ 0				$ 0				0	0
Interest or penalties expense on income taxes										$ 0	$ 0
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets										3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets										7 years
ASC 606 [Member]
Summary Of Significant Accounting Policies [Line Items]
Performance obligation, description of timing										The duration of time between accession receipt and delivery of a valid assay result to the ordering physician or entity is typically less than two weeks.
Practical expedient, description										The Company does not adjust the transaction price for the effects of a significant financing component, as at contract inception, the Company expects the collection cycle to be one year or less.
ASC 606 [Member] \| Maximum [Member] \| Sales and Marketing Expenses [Member]
Summary Of Significant Accounting Policies [Line Items]
Amortization period										1 year

Summary of Significant Accounting Policies - Composition of Net Revenues Recognized Disaggregated by Source (Detail) - USD ($)

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Revenue Recognition [Abstract]

Net revenues from contracted payers

^[1]

$ 1,348,383

$ 2,074,596

Net revenues from non-contracted payers

1,703,179

2,721,717

Development services revenues

198,736

272,350

Total net revenues

$ 859,526

$ 761,591

$ 822,238

$ 806,943

$ 995,226

$ 1,111,411

$ 1,278,961

$ 1,683,065

$ 3,250,298

$ 5,068,663

[1]	Includes Medicare and Medicare Advantage, as reimbursement amounts are fixed and miscellaneous income from CEE-Sure blood collection tubes.

Summary of Significant Accounting Policies - Composition of Net Revenues Recognized Disaggregated by Nature (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Revenue Recognition [Abstract]
Net commercial revenues recognized upon delivery									$ 3,051,562	$ 3,570,337
Development services revenues recognized upon delivery									198,736	272,350
Commercial revenues recognized upon cash collection										1,225,976
Total net revenues	$ 859,526	$ 761,591	$ 822,238	$ 806,943	$ 995,226	$ 1,111,411	$ 1,278,961	$ 1,683,065	$ 3,250,298	$ 5,068,663

Summary of Significant Accounting Policies - Composition of Gross and Net Revenues Recognized (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Revenue Recognition [Abstract]
Commercial revenues recognized upon delivery									$ 12,505,149	$ 15,685,069
Development services revenues recognized upon delivery									198,736	272,350
Commercial revenues recognized upon cash collection										1,225,976
Total gross revenues									12,703,885	17,183,395
Provisions for contractual discounts									(3,937,993)	(5,805,787)
Provisions for aged non-patient receivables									(326,137)	(735,709)
Provisions for estimated patient receivables									(66,470)	(169,479)
Provisions for other payer-specific sales allowances									(5,122,987)	(5,403,757)
Total net revenues	$ 859,526	$ 761,591	$ 822,238	$ 806,943	$ 995,226	$ 1,111,411	$ 1,278,961	$ 1,683,065	$ 3,250,298	$ 5,068,663

Summary of Significant Accounting Policies - Summary of Activity in Gross and Net Accounts Receivable Balances and Reserves (Detail)	12 Months Ended
	Dec. 31, 2018 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Gross and net accounts receivable, Beginning Balance	$ 1,193,426
Amounts Recognized Upon Delivery	3,250,298
Settlements Upon Adjudication	(2,869,399)
Gross and net accounts receivable, Ending Balance	1,574,325
Accounts Receivable Gross [Member]
Summary Of Significant Accounting Policies [Line Items]
Gross and net accounts receivable, Beginning Balance	6,937,063
Amounts Recognized Upon Delivery	12,835,371
Settlements Upon Adjudication	(11,889,832)
Gross and net accounts receivable, Ending Balance	7,882,602
Reserve for Contractual Discounts [Member]
Summary Of Significant Accounting Policies [Line Items]
Gross and net accounts receivable, Beginning Balance	(1,974,849)
Amounts Recognized Upon Delivery	(3,214,615)
Settlements Upon Adjudication	3,011,989
Gross and net accounts receivable, Ending Balance	(2,177,475)
Reserve for Aged Non-patient Receivables [Member]
Summary Of Significant Accounting Policies [Line Items]
Gross and net accounts receivable, Beginning Balance	(452,088)
Amounts Recognized Upon Delivery	(994,542)
Settlements Upon Adjudication	880,682
Gross and net accounts receivable, Ending Balance	(565,948)
Reserve for Estimated Patient Receivables [Member]
Summary Of Significant Accounting Policies [Line Items]
Gross and net accounts receivable, Beginning Balance	(88,120)
Amounts Recognized Upon Delivery	(135,955)
Settlements Upon Adjudication	208,598
Gross and net accounts receivable, Ending Balance	(15,477)
Reserve for Other Payer-specific Sales Allowances [Member]
Summary Of Significant Accounting Policies [Line Items]
Gross and net accounts receivable, Beginning Balance	(3,228,580)
Amounts Recognized Upon Delivery	(5,239,961)
Settlements Upon Adjudication	4,919,164
Gross and net accounts receivable, Ending Balance	$ (3,549,377)

Summary of Significant Accounting Policies - Summary of Third-Party Payers That Represent More Than 10% of Total Net Revenues and Total Net Accounts Receivable and Their Related Percentage (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Customer Concentration Risk [Member] \| Net Revenues [Member] \| Medicare and Medicare Advantage [Member]
Concentration Risk [Line Items]
Concentration risk percentage	39.00%	39.00%
Customer Concentration Risk [Member] \| Net Revenues [Member] \| Blue Cross Blue Shield [Member]
Concentration Risk [Line Items]
Concentration risk percentage	11.00%	19.00%
Customer Concentration Risk [Member] \| Net Revenues [Member] \| United Healthcare [Member]
Concentration Risk [Line Items]
Concentration risk percentage	17.00%	12.00%
Credit Concentration Risk [Member] \| Net Accounts Receivable [Member] \| Medicare and Medicare Advantage [Member]
Concentration Risk [Line Items]
Concentration risk percentage	17.00%	21.00%
Credit Concentration Risk [Member] \| Net Accounts Receivable [Member] \| Blue Cross Blue Shield [Member]
Concentration Risk [Line Items]
Concentration risk percentage	22.00%	27.00%
Credit Concentration Risk [Member] \| Net Accounts Receivable [Member] \| United Healthcare [Member]
Concentration Risk [Line Items]
Concentration risk percentage	15.00%	15.00%

Sales of Equity Securities - Additional Information (Detail) - USD ($)											1 Months Ended		12 Months Ended
	Nov. 28, 2018	Sep. 20, 2018	Aug. 13, 2018	Jan. 31, 2018	Jan. 30, 2018	Dec. 08, 2017	Aug. 11, 2017	Aug. 09, 2017	Mar. 31, 2017	May 04, 2016	May 31, 2018	May 31, 2015	Dec. 31, 2018	Dec. 31, 2017
Class Of Stock [Line Items]
Shelf registration statement expiration period												May 21, 2018
Minimum public float limit for offering											$ 75,000,000
Public offering, number of shares issued		642,438
Issuance of unregistered warrants to purchase shares of common stock		762,438	2,549,140			8,208		47,821	72,000
Proceeds from exercise of common stock warrants							$ 0						$ 1,200	$ 7,498,535
Beginning stock price		$ 3.285			$ 13.50
Issuance of warrants to purchase shares of common stock, grant date fair value		$ 2,000,000	$ 8,400,000		$ 9,700,000	$ 100,000		$ 1,500,000	$ 2,800,000
Exercise price of unregistered warrants			$ 4.53		$ 3.16	$ 25.50	$ 45.00	$ 45.00	$ 75.00				$ 3.16
Class of warrant or rights, expiration date						Dec. 05, 2022
Net cash proceeds from sale of securities								$ 2,000,000
Proceeds from issuance of common stock		2,500,000	$ 11,600,000				$ 2,200,000
Class of warrant or rights, term			5 years		5 years
Aggregate units sold under right offering			11,587
Warrant exercisable for share of common stock			1
Series A Preferred Stock convertible to common stock, conversion price			$ 4.53
Net proceeds from issuance of units, net of issuance expenses		$ 2,200,000	$ 10,100,000
Common stock, par value			$ 0.0001										$ 0.0001	$ 0.0001
Public offering, number of common stock and warrants issued		642,438			1,095,153
Prefunded Warrants [Member]
Class Of Stock [Line Items]
Proceeds from exercise of common stock warrants	$ 1,200
Exercise price of unregistered warrants		$ 3.275
Issuance of warrants to purchase shares of common stock		120,000
Change in exercise price of warrants		$ 0.01
Warrants [Member]
Class Of Stock [Line Items]
Exercise price of unregistered warrants					$ 15.00
Class of warrant or rights, expiration date													Mar. 24, 2024
Class of warrant or rights, term					5 years
Aggregate warrants sold under right offering			2,549,140
Series A Preferred Stock [Member]
Class Of Stock [Line Items]
Public offering, number of shares issued			11,587
Preferred stock stated value per share			$ 1,000
Ally Bridge [Member]
Class Of Stock [Line Items]
Proceeds from exercise of common stock warrants							$ 0
Beginning stock price								$ 45.00
Issuance of warrants to purchase shares of common stock, grant date fair value								$ 1,500,000
Exercise price of unregistered warrants								$ 45.00
Net cash proceeds from sale of securities								$ 2,000,000
Private offering, number of common stock and warrants issued								48,888
Issuance of warrants to purchase shares of common stock								47,821
Proceeds from issuance of common stock								$ 2,200,000
Class of warrant or rights, term								5 years
Common stock issuance costs								$ 200,000
Roth Capital Partners, LLC, WestPark Capital and Chardan Capital [Member]
Class Of Stock [Line Items]
Placement agent agreement, effective date									Mar. 28, 2017
Public offering, number of shares issued									144,000
Issuance of unregistered warrants to purchase shares of common stock									72,000
Proceeds from exercise of common stock warrants									$ 0
Beginning stock price									$ 64.50
Issuance of warrants to purchase shares of common stock, grant date fair value									$ 2,800,000
Exercise price of unregistered warrants									$ 75.00
Class of warrant or rights, expiration date									Oct. 01, 2022
Cost directly associated with offering									$ 700,000
Net cash proceeds from sale of securities									$ 8,600,000
Dawson James Securities, Inc and WestPark Capital [Member]
Class Of Stock [Line Items]
Placement agent agreement, effective date						Dec. 05, 2017
Public offering, number of shares issued						164,166
Issuance of unregistered warrants to purchase shares of common stock						8,208
Beginning stock price						$ 20.40
Issuance of warrants to purchase shares of common stock, grant date fair value						$ 100,000
Exercise price of unregistered warrants						$ 25.50
Class of warrant or rights, expiration date						Dec. 05, 2022
Cost directly associated with offering						$ 400,000
Net cash proceeds from sale of securities						$ 2,900,000
Maximum [Member]
Class Of Stock [Line Items]
Issuance of unregistered warrants to purchase shares of common stock					1,095,153
Issuance of warrants to purchase shares of common stock					1,095,153
Maximum [Member] \| Prefunded Warrants [Member]
Class Of Stock [Line Items]
Issuance of warrants to purchase shares of common stock		120,000
Maximum [Member] \| Warrants [Member]
Class Of Stock [Line Items]
Issuance of warrants to purchase shares of common stock					1,095,153
Shelf Registration Statement [Member]
Class Of Stock [Line Items]
Shelf registration statement expiration period											May 31, 2021
Minimum public float limit for offering											$ 75,000,000	$ 75,000,000
Placement agent agreement, effective date										Apr. 25, 2016
Proceeds from exercise of common stock warrants										$ 0
Net cash proceeds from sale of securities										$ 4,300,000
Shelf Registration Statement [Member] \| Maximum [Member]
Class Of Stock [Line Items]
Aggregate offering price											$ 50,000,000	$ 50,000,000
Follow-on Public Offering [Member]
Class Of Stock [Line Items]
Proceeds from exercise of common stock warrants				$ 0	$ 0
Beginning stock price					$ 13.50
Issuance of warrants to purchase shares of common stock, grant date fair value					$ 9,700,000
Exercise price of unregistered warrants		$ 3.16	$ 4.53		$ 3.16
Cost directly associated with offering					$ 1,400,000
Net cash proceeds from sale of securities					$ 13,300,000
Private offering, number of common stock and warrants issued					1,095,153
Class of warrant or rights, term		5 years	5 years		5 years
Follow-on Public Offering [Member] \| Maximum [Member]
Class Of Stock [Line Items]
Issuance of warrants to purchase shares of common stock					1,095,153
Private Placement [Member]
Class Of Stock [Line Items]
Exercise price of unregistered warrants		$ 3.16
Class of warrant or rights, term		5 years
Warrant exercisable for share of common stock		1

Fair Value Measurements - Additional Information (Detail) - USD ($)										12 Months Ended
	Nov. 28, 2018	Sep. 20, 2018	Aug. 13, 2018	Jan. 31, 2018	Jan. 30, 2018	Dec. 08, 2017	Aug. 11, 2017	Aug. 09, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed asset purchases as equipment financings obligations										$ 279,000	$ 719,000
Issuance of unregistered warrants to purchase shares of common stock, grant date fair value		$ 2,000,000	$ 8,400,000		$ 9,700,000	$ 100,000		$ 1,500,000	$ 2,800,000
Issuance of unregistered warrants to purchase shares of common stock		762,438	2,549,140			8,208		47,821	72,000
Estimated grant date fair value of warrants		$ 2.57	$ 3.30		$ 8.82	$ 15.60		$ 30.90	$ 39.30
Exercise price of unregistered warrants			$ 4.53		$ 3.16	$ 25.50	$ 45.00	$ 45.00	$ 75.00	$ 3.16
Class of warrant or rights, term			5 years		5 years
Common stock warrants outstanding, intrinsic value										$ 0
Proceeds from exercise of common stock warrants							$ 0			1,200	7,498,535
Prefunded Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Exercise price of unregistered warrants		$ 3.275
Issuance of warrants to purchase shares of common stock		120,000
Common stock warrants outstanding, intrinsic value		$ 350,000
Proceeds from exercise of common stock warrants	$ 1,200
Follow-on Public Offering [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Issuance of unregistered warrants to purchase shares of common stock, grant date fair value					$ 9,700,000
Exercise price of unregistered warrants		$ 3.16	$ 4.53		$ 3.16
Class of warrant or rights, term		5 years	5 years		5 years
Proceeds from exercise of common stock warrants				$ 0	$ 0
Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Issuance of unregistered warrants to purchase shares of common stock					1,095,153
Issuance of warrants to purchase shares of common stock					1,095,153
Maximum [Member] \| Prefunded Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Issuance of warrants to purchase shares of common stock		120,000
Maximum [Member] \| Follow-on Public Offering [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Issuance of warrants to purchase shares of common stock					1,095,153
Estimated Fair Value Measurements, Nonrecurring [Member] \| Level 3 Inputs [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed asset purchases as equipment financings obligations										$ 279,000	$ 719,000

Balance Sheet Details - Schedule of Fixed Assets and Accrued Liabilities (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Fixed Assets
Machinery and equipment	$ 2,818,583	$ 2,841,388
Furniture and office equipment	157,391	147,976
Computer equipment and software	1,437,408	1,637,034
Leasehold improvements	570,173	553,529
Financed equipment	2,573,955	2,294,762
Construction in process	116,640	2,975
Total fixed assets, gross	7,674,150	7,477,664
Less accumulated depreciation and amortization	(4,934,728)	(4,354,097)
Total fixed assets, net	2,739,422	3,123,567
Accrued Liabilities
Accrued interest		326,602
Accrued payroll	255,426	224,813
Accrued vacation	535,682	474,953
Accrued bonuses	712,574	375,000
Accrued sales commissions	62,767	104,509
Current portion of deferred rent	158,342	116,681
Accrued other	203,602	129,805
Total accrued liabilities	$ 1,928,393	$ 1,752,363

April 2014 Credit Facility - Additional Information (Detail) - USD ($)								12 Months Ended
	Sep. 20, 2018	Aug. 13, 2018	Jan. 30, 2018	Dec. 08, 2017	Aug. 09, 2017	Mar. 31, 2017	Apr. 30, 2014	Dec. 31, 2018	Dec. 31, 2014	Dec. 31, 2017	Aug. 11, 2017
Line of Credit Facility [Line Items]
Exercise price of unregistered warrants		$ 4.53	$ 3.16	$ 25.50	$ 45.00	$ 75.00		$ 3.16			$ 45.00
Warrant term				5 years	5 years	5 years
Issuance of unregistered warrants to purchase shares of common stock, grant date fair value	$ 2,000,000	$ 8,400,000	$ 9,700,000	$ 100,000	$ 1,500,000	$ 2,800,000
Remaining outstanding principal payment										$ 1,168,811
Oxford Finance LLC [Member] \| Common Stock [Member]
Line of Credit Facility [Line Items]
Warrant issued to lender							588
Exercise price of unregistered warrants							$ 424.80
Warrant term							10 years
Oxford Finance LLC [Member] \| First Term Loan [Member]
Line of Credit Facility [Line Items]
Net cash proceeds on term loan							$ 4,898,000
Line of Credit Facility fees amount payable							$ 50,000
Line of Credit Facility, interest rate during period							7.95%
Percentage of final interest payment due at maturity							5.50%
Issuance costs									$ 102,000
Net proceeds from credit facility									4,898,000
Issuance of unregistered warrants to purchase shares of common stock, grant date fair value									$ 233,000
Unamortized discounts										$ 33,000
Effective annual interest rate										13.87%
Total remaining principal payments due during fiscal year ending December 31, 2018										$ 1,201,000
Remaining outstanding principal payment								$ 0
Total remaining principal payment paid								$ 1,201,000

Equipment Financings - Additional Information (Detail)				3 Months Ended	10 Months Ended	12 Months Ended
Equipment Financings - Additional Information (Detail)	Jan. 26, 2018 USD ($) Payment	Nov. 02, 2017 USD ($)	Oct. 17, 2017 USD ($) mo	Dec. 31, 2018 USD ($)	Nov. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Capital Leased Assets [Line Items]
Financed equipment				$ 2,573,955		$ 2,573,955	$ 2,294,762
Accumulated depreciation related to financed equipment				1,135,000		1,135,000	759,000
Fixed asset purchases as equipment financings						279,000	719,000
Total proceeds from equipment financing commitment							150,848
Machinery and equipment				2,818,583		2,818,583	2,841,388
Machinery and equipment, accumulated depreciation				4,934,728		$ 4,934,728	$ 4,354,097
Equipment financings aggregate weighted average effective annual interest rate						12.53%	13.51%
Equipment financings maturity date on outstanding arrangements range, Start						2018-06
Equipment financings maturity date on outstanding arrangements range, End						2024-09
Interest expense to equipment financings						$ 310,976	$ 482,623
Present value of minimum lease payment due within one year				642,000		642,000
Fixed asset purchases	$ 250,000					145,253	1,400,180
Number of lease payments \| Payment	22
Lease payments per month	$ 15,274
Equipment purchases				$ 332,000		332,000
Rental charges						1,272,000	1,272,000
Equipment Financings [Member]
Capital Leased Assets [Line Items]
Depreciation expense related to financed equipment						376,000	234,000
Total proceeds from equipment financing commitment		$ 151,000
Sale-leaseback transaction, aggregate gross value of fixed assets			$ 167,000
Sale-leaseback transaction, net book value of fixed assets			$ 162,000
Sale-leaseback transaction, frequency of payments			monthly
Sale-leaseback transaction, number of installments payments \| mo			36
Sale-leaseback transaction, montly installments of principal and interest payments			$ 4,884
Sale-leaseback transaction, total amount to be repaid			$ 176,000
Sale-leaseback transaction, commitment period			2020-10
Interest expense to equipment financings						$ 237,000	171,000
Rental charges					$ 124,000
Machinery and Equipment [Member]
Capital Leased Assets [Line Items]
Machinery and equipment							189,000
Machinery and equipment, accumulated depreciation							155,000
Machinery and equipment, net book values							$ 34,000
Minimum [Member]
Capital Leased Assets [Line Items]
Financed equipment useful life						3 years
Minimum [Member] \| Equipment Financings [Member]
Capital Leased Assets [Line Items]
Financed equipment useful life						5 years
Maximum [Member]
Capital Leased Assets [Line Items]
Financed equipment useful life						7 years
Maximum [Member] \| Equipment Financings [Member]
Capital Leased Assets [Line Items]
Financed equipment useful life						7 years

Equipment Financings - Schedule of Remaining Future Minimum Lease Payments for Financed Equipment Obligations (Detail)	Dec. 31, 2018 USD ($)
Capital Lease Obligations [Abstract]
2019	$ 670,896
2020	551,610
2021	305,006
2022	264,600
Thereafter	310,932
Total payments	2,103,044
Less amount representing interest	476,493
Present value of payments	1,626,551
2019	91,285
2020	72,635
2021	51,473
2022	60,832
Thereafter	45,710
Total payments	321,935
Present value of payments	$ 321,935

Supplier Financings - Additional Information (Detail) - Financing Agreements With Supplier [Member] - Laboratory Software [Member] - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018
Debt Instrument [Line Items]
Financing agreement, due period	1 year
Remaining balance under financing agreement	$ 61,000	$ 0
Minimum [Member]
Debt Instrument [Line Items]
Interest rate	4.40%	4.40%
Maximum [Member]
Debt Instrument [Line Items]
Interest rate	6.20%	6.20%

Stock-Based Compensation - Additional Information (Detail)						3 Months Ended	12 Months Ended
	Jun. 28, 2018 shares	Jul. 31, 2017 $ / shares	May 31, 2017 $ / shares shares	Jul. 29, 2016 $ / shares shares	Jul. 25, 2016 $ / shares shares	Mar. 28, 2018 shares	Dec. 31, 2018 USD ($) Plan $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 $ / shares shares	Jul. 06, 2017 shares	May 02, 2017 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of equity incentive plans \| Plan							2
Total Shares Outstanding							195,820	81,643	29,888
Weighted average exercise price per share \| $ / shares							$ 2.20	$ 44.70
Number of shares remaining forfeited							28,410	6,746
Number of Shares, Granted							142,587	58,501
Unrecognized share-based compensation expense, weighted-average recognition period							2 years 1 month 17 days
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Estimated forfeitures rate							8.00%	8.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Estimated forfeitures rate							0.00%	0.00%
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period							10 years
Option awards assumptions, method used							Black-Scholes pricing model
Weighted-average estimated fair value of options granted \| $ / shares							$ 1.75	$ 1.02
Intrinsic value of options outstanding \| $							$ 0	$ 0
Intrinsic value of options exercisable \| $							0	0
Intrinsic value of options vested and unvested expected to vest \| $							$ 0	0
Stock Options [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period							4 years
Employee Stock Option One [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Time period for vesting grants in installments on monthly basis							monthly thereafter for the remaining three years
Employee Stock Option Two [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options vesting term							monthly vesting beginning month-one after the grant and monthly thereafter
RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period									1 year
Intrinsic value shares, RSUs outstanding \| $							$ 300,000,000	$ 250,000
Intrinsic value amount, RSUs unvested and vested expected to vest \| $							$ 300,000,000
RSUs outstanding							360	12,030	5,808
Intrinsic value amount, RSUs unvested and vested expected to vest \| $								$ 129,000
Issuance of restricted stock units								11,666
Weighted-average estimated fair value of options granted \| $ / shares							$ 415.80	$ 56.10	$ 80.40
Total RSUs forfeited							5,835	250
Stock Options and RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized share-based compensation expense, stock options \| $							$ 667,000
Options Vesting on One Year Anniversary [Member] \| Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of Overall Stock Grant Subject to Vesting							25.00%
2013 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock options and RSUs authorized							124,211
2013 Equity Incentive Plan [Member] \| Chief Financial Officer [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average exercise price per share \| $ / shares					$ 58.50
Number of shares remaining forfeited								565
2013 Equity Incentive Plan [Member] \| Performance Stock Options Granted on July 29 2016 [Member] \| Chief Financial Officer [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options vested								546
2013 Equity Incentive Plan [Member] \| Performance Stock Options [Member}
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average estimated fair value of options granted \| $ / shares		$ 24.90	$ 29.70
Weighted average exercise price per share \| $ / shares		$ 41.70	$ 45.00
2013 Equity Incentive Plan [Member] \| Performance Stock Options [Member} \| Chief Financial Officer [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Granted			3,333
2013 Equity Incentive Plan [Member] \| Performance Stock Options [Member} \| Employees and Executive Officers [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares authorized											18,333
Stock options vested						0
Number of shares remaining forfeited						20,750
2013 Equity Incentive Plan [Member] \| Performance Stock Options [Member} \| Employees [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares authorized										2,500
Number of shares remaining forfeited								2,500
2013 Equity Incentive Plan [Member] \| Performance Stock Options [Member} \| Chief Executive Officer [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Granted			6,666
2013 Equity Incentive Plan [Member] \| Performance Stock Options [Member} \| Chief Scientific Officer [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Granted			2,500
2013 Equity Incentive Plan [Member] \| Performance Stock Options [Member} \| Senior Medical Director [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Granted			2,500
2013 Equity Incentive Plan [Member] \| Time-Based RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period								1 year
Weighted-average estimated fair value of options granted \| $ / shares			$ 45.00
2013 Equity Incentive Plan [Member] \| Time-Based RSUs [Member] \| Chief Executive Officer [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of restricted stock units			1,666
2013 Equity Incentive Plan [Member] \| Time-Based RSUs [Member] \| Executive Officer [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares authorized											5,833
2013 Equity Incentive Plan [Member] \| Time-Based RSUs [Member] \| Other Executive Officers [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of restricted stock units			833
2013 Equity Incentive Plan [Member] \| Performance RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average estimated fair value of options granted \| $ / shares			$ 45.00
2013 Equity Incentive Plan [Member] \| Performance RSUs [Member] \| Chief Executive Officer [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of restricted stock units			833
2013 Equity Incentive Plan [Member] \| Performance RSUs [Member] \| Executive Officer [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares authorized											5,833
2013 Equity Incentive Plan [Member] \| Performance RSUs [Member] \| Other Executive Officers [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of restricted stock units			833
2013 Equity Incentive Plan [Member] \| Performance RSU Granted on May 31, 2017 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of vested shares issued						0
Total RSUs forfeited						5,833
2013 Equity Incentive Plan [Member] \| Non-inducement Shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock options and RSUs authorized							264,098
Increase in number of shares of common stock authorized for issuance	146,666
Stock options and RSUs issued							95,258
Total Shares Outstanding							79,300
Common stock, shares authorized							168,840
2013 Equity Incentive Plan [Member] \| Inducement shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options and RSUs issued							118,368
Total Shares Outstanding							117,534
Common stock, shares authorized							0
2013 Equity Incentive Plan [Member] \| Options Vesting on One Year Anniversary [Member] \| Chief Financial Officer [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock options and RSUs authorized					2,222
Vesting period					1 year
Percentage of Overall Stock Grant Subject to Vesting					25.00%
Weighted-average estimated fair value of options granted \| $ / shares					$ 43.50
Stock option units remaining vesting period on Equal monthly basis					3 years
2013 Equity Incentive Plan [Member] \| Options Vesting on Performance Achievement [Member] \| Chief Financial Officer [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock options and RSUs authorized				1,111
Weighted-average estimated fair value of options granted \| $ / shares				$ 37.80

Stock-Based Compensation - Assumptions Used for Determining Fair Value of Stock Options Under Black-Scholes Pricing Model (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock and exercise prices	$ 0.86	$ 20.82
Discount rate-bond equivalent yield	2.50%	1.79%
Expected life (in years)	4 years	5 years 1 month 13 days
Expected volatility	100.00%	70.00%
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock and exercise prices	$ 6.00	$ 63.90
Discount rate-bond equivalent yield	3.02%	2.27%
Expected life (in years)	5 years 11 months 15 days	6 years 1 month 2 days
Expected volatility	120.00%	90.00%

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares Outstanding, Beginning Balance	81,643	29,888
Number of Shares, Granted	142,587	58,501
Number of Shares, Cancelled/forfeited/expired	(28,410)	(6,746)
Number of Shares Outstanding, Ending Balance	195,820	81,643	29,888
Number of Shares, Vested and unvested expected to vest, Ending Balance	183,136
Weighted Average Exercise Price Per Share, Outstanding, Beginning Balance	$ 113.68	$ 264.00
Weighted Average Exercise Price Per Share, Granted	2.20	44.70
Weighted Average Exercise Price Per Share, Cancelled/forfeited/expired	57.96	143.10
Weighted Average Exercise Price Per Share, Outstanding, Ending Balance	41.41	$ 113.68	$ 264.00
Weighted Average Exercise Price Per Share, Vested and unvested expected to vest, Ending Balance	$ 44.02
Weighted Average Remaining Contractual Term in Years, Outstanding	9 years 2 months 12 days	8 years 9 months 18 days	8 years 6 months
Weighted Average Remaining Contractual Term in Years, Vested and unvested expected to vest	9 years 1 month 6 days

Stock-Based Compensation - Summary of RSU Activity (Detail) - RSUs [Member] - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares Outstanding, Beginning Balance	12,030	5,808
Number of Shares, Granted		11,666
Number of share, Vested and issued	(5,835)	(5,194)
Number of share, Forfeited	(5,835)	(250)
Number of Shares Outstanding, Ending Balance	360	12,030
Number of Shares, Vested and unvested expected to vest, Ending Balance	360
Weighted Average Grand Date Fair Value, Outstanding, Beginning Balance	$ 56.10	$ 80.40
Weighted Average Grand Date Fair Value, Granted		45.00
Weighted Average Grand Date Fair Value,Vested and issued	45.00	58.80
Weighted Average Grand Date Fair Value, Forfeited	45.00	63.60
Weighted Average Grand Date Fair Value, Outstanding, Ending Balance	415.80	$ 56.10
Weighted Average Grant Date Fair Value, Vested and unvested expected to vest, Ending Balance	$ 415.80

Stock-Based Compensation - Effects of Stock-Based Compensation Related to Equity Awards to Employees and Nonemployees on Statement of Operations (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 558,987	$ 929,822
Stock Options [Member] \| Cost of revenues [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	46,708	142,400
Stock Options [Member] \| Research and Development Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	133,525	143,300
Stock Options [Member] \| General and Administrative Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	300,433	575,741
Stock Options [Member] \| Sales and Marketing Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	78,321	68,381
RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	623,412	1,247,481
RSUs [Member] \| Cost of revenues [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	(18,802)	48,745
RSUs [Member] \| Research and Development Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	13,576	55,941
RSUs [Member] \| General and Administrative Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	54,302	160,937
RSUs [Member] \| Sales and Marketing Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 15,349	$ 52,036

Common Stock Warrants Outstanding - Summary of Equity-Classified Common Stock Warrant Activity, for Warrants Other than Underlying Unexercised Overallotment Option Warrants (Detail) - Warrants [Member] - $ / shares		12 Months Ended
	Sep. 24, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class Of Warrant Or Right [Line Items]
Number of Shares, Outstanding, Beginning Balance		288,196	387,395
Number of Shares, Issued	762,438	4,526,661	128,029
Number of Shares, Exercised		(120,000)	(227,228)
Number of Shares, Outstanding, Ending Balance		4,694,927	288,196	387,395
Weighted Average Exercise Price Per Share, Outstanding, Beginning Balance		$ 78.86	$ 57.90
Weighted Average Exercise Price Per Share, Issued		3.85	60.62
Weighted Average Exercise Price Per Share, Exercised		0.01	33.00
Weighted Average Exercise Price Per Share, Outstanding, Ending Balance		$ 8.55	$ 78.86	$ 57.90
Average Remaining Contractual Term (in years)		4 years 4 months 24 days	4 years	4 years 7 months 6 days

Common Stock Warrants Outstanding - Additional Information (Detail) - USD ($)					12 Months Ended
	Sep. 24, 2018	Aug. 13, 2018	Jan. 30, 2018	Dec. 08, 2017	Dec. 31, 2018	Dec. 31, 2017	Aug. 11, 2017	Aug. 09, 2017	Mar. 31, 2017
Class Of Warrant Or Right [Line Items]
Class of warrant or rights, first exercisable date				Jun. 05, 2018
Class of warrant or rights, expiration date				Dec. 05, 2022
Common stock warrants outstanding, intrinsic value					$ 0
Exercise price of unregistered warrants		$ 4.53	$ 3.16	$ 25.50	$ 3.16		$ 45.00	$ 45.00	$ 75.00
Class of warrant or rights, term		5 years	5 years
Maximum [Member]
Class Of Warrant Or Right [Line Items]
Issuance of warrants to purchase shares of common stock			1,095,153
Warrants [Member]
Class Of Warrant Or Right [Line Items]
Warrants issued	762,438				4,526,661	128,029
Class of warrant or rights, first exercisable date					Mar. 24, 2019
Class of warrant or rights, expiration date					Mar. 24, 2024
Exercise price of unregistered warrants			$ 15.00
Class of warrant or rights, term			5 years
Warrants [Member] \| Maximum [Member]
Class Of Warrant Or Right [Line Items]
Issuance of warrants to purchase shares of common stock			1,095,153

Net Loss per Common Share - Schedule of Anti-Dilutive Securities Excluded from Computations of Diluted Weighted-Average Shares (Detail) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	5,867,281	381,886
Warrants Outstanding [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	4,694,927	288,196
RSUs Outstanding [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	360	12,030
Preferred Warrants Outstanding [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	17	17
Convertible Preferred Stock Outstanding [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	976,157
Common Options Outstanding [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	195,820	81,643

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Corporate tax rate	21.00%	35.00%
Decrease in net deferred tax assets		$ 2,600,000
Deferred tax benefit or expense	$ 2,600,000
Percent of uncertain income tax positions recognized	50.00%	50.00%
Liability for unrecognized tax benefits	$ 0	$ 0
Percentage of change in ownership	50.00%
Period of change in ownership	3 years
Federal [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 13,600,000
Net operating loss carryforwards, expiration year	expiring beginning in 2035
Additional net operating loss carryforwards	$ 23,600,000
Federal [Member] \| Maximum [Member]
Income Tax Contingency [Line Items]
Percentage of future taxable income offset by operating loss carryforwards	80.00%
Federal [Member] \| Research Tax Credit Carryforward [Member]
Income Tax Contingency [Line Items]
Research and development tax credits	$ 160,000
Income tax research and development expiration year	begin to expire in 2035
California [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 24,700,000
Net operating loss carryforwards, expiration year	expiring beginning in 2023
California [Member] \| Research Tax Credit Carryforward [Member]
Income Tax Contingency [Line Items]
Research and development tax credits	$ 3,543,000

Income Taxes - Schedule of Provision for Income Taxes (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Current:
State	$ 1,886	$ 7,624
Total	1,886	7,624
Deferred
Provision for income tax	$ 1,886	$ 7,624

Income Taxes - Reconciles of Income Taxes Computed at Federal Statutory Rate and Provision for Income Taxes (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax at statutory rate	$ (5,159,881)	$ (7,346,079)
Change in federal tax rate		2,621,803
State liability	(670,015)	(411,853)
Permanent items	118,959	214,313
Stock compensation	11,128	72,696
Nondeductible interest		15,568
Expiration of net operating losses		922,307
Research and development credit	(272,314)	(200,379)
State rate change	(132,855)	(18,026)
Estimated section 382 limitation		1,491,942
Return to provision	8,386	365,263
Other	19,420	488,264
Valuation allowance	6,079,058	1,791,805
Provision for income tax	$ 1,886	$ 7,624

Income Taxes - Summary of Deferred Tax Assets (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Estimated net operating loss carryforward	$ 9,229,174	$ 3,699,532
Estimated research and development credits	2,958,710	2,686,665
Accruals and other	2,864,028	2,560,419
Deferred rent	64,628	90,866
Gross deferred tax assets	15,116,540	9,037,482
Less valuation allowance	$ (15,116,540)	$ (9,037,482)

Related Party Transactions - Additional Information (Detail)		3 Months Ended	12 Months Ended
	Feb. 01, 2017	Mar. 31, 2015	Dec. 31, 2018 USD ($) ft²	Dec. 31, 2017 USD ($)	Nov. 30, 2011 ft²
Related Party Transaction [Line Items]
Lease expiration date			Jul. 31, 2020
San Diego California Facility [Member]
Related Party Transaction [Line Items]
Leased facility, expansion of original premises \| ft²					9,849
Lease expiration date	Mar. 31, 2017		Oct. 31, 2018
Rental income			$ 0	$ 51,000
Aegea Biotechnologies, Inc [Member]
Related Party Transaction [Line Items]
Reimbursement for shared patent costs			$ 19,000	$ 15,000
Nonexecutive [Member] \| San Diego California Facility [Member]
Related Party Transaction [Line Items]
Leased facility, expansion of original premises \| ft²			9,849
Lease agreement date of commencement			Mar. 30, 2015
Leased facility, rent expense per month			$ 12,804
Lease facility, refundable security deposit amount			12,804
Lease expiration date		Jul. 31, 2015
Lease agreement, amount of security deposit applied against additional rents owed			16,000
Lease agreement, amount of additional rents waived			$ 3,200

Commitments and Contingencies - Additional Information (Detail)		1 Months Ended	12 Months Ended
	Feb. 01, 2017	Feb. 29, 2016 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2012	Nov. 30, 2011 ft²
Loss Contingencies [Line Items]
Lease expiration date			Jul. 31, 2020
Total rent expense			$ 1,272,000	$ 1,272,000
Unconditional purchase commitment aggregate amount		$ 1,062,500	$ 341,000
Unconditional purchase commitment payment terms			Quarterly
Unconditional purchase commitment period			May 31, 2020
Total expense for sales tax and maintenance obligations			$ 101,000	$ 79,000
Sales tax and maintenance obligations incurred but not paid			91,285
Total payments for future sales tax and maintenance obligations			321,935
Accrued Other Liabilities [Member]
Loss Contingencies [Line Items]
Sales tax and maintenance obligations incurred but not paid			$ 69,000
Minimum [Member]
Loss Contingencies [Line Items]
Unconditional purchase commitment, quarterly payment amount		$ 62,500
San Diego California Facility [Member]
Loss Contingencies [Line Items]
Initial lease term					8 years
Lease expiration date	Mar. 31, 2017		Oct. 31, 2018
Leased facility, expansion of original premises \| ft²						9,849

Commitments and Contingencies - Schedule of Future Minimum Lease Payments (Detail)	Dec. 31, 2018 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 1,430,366
2020	855,136
Total	$ 2,285,502

Selected Quarterly Financial Data (Unaudited) - Summary of Selected Quarterly Financial Data (Detail) - USD ($)

1 Months Ended

3 Months Ended

12 Months Ended

Sep. 30, 2018

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Balance sheet data:

Cash

$ 8,956,200

$ 3,423,373

$ 8,956,200

$ 2,569,111

$ 9,272,420

$ 2,146,611

$ 5,879,025

$ 10,000,155

$ 14,042,388

$ 3,423,373

$ 2,146,611

$ 4,609,332

Total assets

14,551,892

8,750,303

14,551,892

8,291,310

14,747,827

7,378,906

11,120,215

14,653,193

17,933,413

8,750,303

7,378,906

Total non-current liabilities

1,174,397

1,098,137

1,174,397

1,258,261

1,357,193

1,421,527

1,255,939

1,561,520

2,062,544

1,098,137

1,421,527

Total shareholders’ equity

8,938,408

3,042,519

8,938,408

2,527,568

8,507,714

1,296,034

4,026,079

7,342,257

10,418,069

3,042,519

1,296,034

$ 658,661

Statement of operations and comprehensive loss data:

Net revenues

859,526

761,591

822,238

806,943

995,226

1,111,411

1,278,961

1,683,065

3,250,298

5,068,663

Cost of revenues

2,435,262

2,481,916

2,699,671

2,434,886

2,359,909

2,487,054

2,368,705

2,129,454

10,051,735

9,345,122

Research and development expenses

1,288,957

1,089,746

1,019,285

1,070,584

908,800

856,698

841,991

757,258

4,468,572

3,364,747

General and administrative expenses

1,632,670

1,793,720

1,708,970

1,938,664

1,650,097

1,834,771

1,798,026

1,906,635

7,074,024

7,189,529

Sales and marketing expenses

1,440,798

1,404,192

1,433,174

1,636,542

1,642,941

1,675,852

1,746,867

1,278,311

5,914,706

6,343,971

Loss from operations

(5,938,161)

(6,007,983)

(6,038,862)

(6,273,733)

(5,566,521)

(5,742,964)

(5,476,628)

(4,388,593)

(24,258,739)

(21,174,706)

Net loss

(6,014,312)

(6,047,784)

(6,153,101)

(6,356,404)

$ (5,666,573)

$ (5,821,306)

$ (5,693,151)

$ (4,432,707)

(24,571,601)

(21,613,737)

Deemed dividend related to warrants down round provision

$ (636,000)

(636,370)

Net loss attributable to common shareholders

$ (6,014,312)

$ (6,684,154)

$ (6,153,101)

$ (6,356,404)

$ (25,207,971)

$ (21,613,737)

Net loss per common share:

Basic

$ (1.43)

^[1]

$ (2.42)

^[1]

$ (2.70)

^[1]

$ (3.33)

^[1]

$ (5.36)

^[1]

$ (5.85)

^[1]

$ (6.32)

^[1]

$ (6.27)

^[1]

$ (9.01)

$ (23.58)

Diluted

$ (1.43)

^[1]

$ (2.42)

^[1]

$ (2.70)

^[1]

$ (3.33)

^[1]

$ (5.36)

^[1]

$ (5.85)

^[1]

$ (6.32)

^[1]

$ (6.27)

^[1]

$ (9.01)

$ (23.58)

Weighted-average shares outstanding used in computing net loss per share attributable to common shareholders:

Basic

4,209,221

2,767,440

2,280,115

1,911,282

1,058,055

995,254

901,007

707,389

2,798,243

916,599

Diluted

4,209,221

2,759,614

2,280,115

1,911,282

1,058,055

995,254

901,007

707,389

2,798,243

916,599

[1]	Basic and diluted net loss per common share are computed independently for each of the components and quarters presented. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted net loss per common share.

Subsequent Events - Additional Information (Detail) - USD ($)											12 Months Ended
	Mar. 19, 2019	Mar. 11, 2019	Feb. 12, 2019	Jan. 18, 2019	Sep. 20, 2018	Aug. 13, 2018	Jan. 31, 2018	Jan. 30, 2018	Aug. 11, 2017	Aug. 09, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 08, 2017	Mar. 31, 2017
Subsequent Event [Line Items]
Shares issued in offering					642,438
Proceeds from issuance of common stock, net of issuance costs										$ 2,000,000
Beginning stock price					$ 3.285			$ 13.50
Exercise price of unregistered warrants						$ 4.53		$ 3.16	$ 45.00	$ 45.00	$ 3.16		$ 25.50	$ 75.00
Class of warrant or rights, term						5 years		5 years
Proceeds from exercise of common stock warrants									$ 0		$ 1,200	$ 7,498,535
Warrant exercisable for share of common stock						1
Follow-on Public Offering [Member]
Subsequent Event [Line Items]
Proceeds from issuance of common stock, net of issuance costs								$ 13,300,000
Beginning stock price								$ 13.50
Exercise price of unregistered warrants					$ 3.16	$ 4.53		$ 3.16
Class of warrant or rights, term					5 years	5 years		5 years
Proceeds from exercise of common stock warrants							$ 0	$ 0
Subsequent Event [Member]
Subsequent Event [Line Items]
Shares issued in offering	5,950,000			990,000
Proceeds from issuance of common stock, net of issuance costs	$ 7,500,000			$ 2,000,000
Beginning stock price	$ 1.37			$ 2.25
Exercise price of unregistered warrants	$ 1.25		$ 1.20
Class of warrant or rights, term	5 years 6 months
Warrant exercisable for share of common stock	1
Subsequent Event [Member] \| Follow-on Public Offering [Member]
Subsequent Event [Line Items]
Shares issued in offering			6,250,000
Proceeds from issuance of common stock, net of issuance costs		$ 601,000	$ 6,800,000
Beginning stock price		$ 1.20	$ 1.20
Exercise price of unregistered warrants			$ 1.20
Class of warrant or rights, term			5 years
Proceeds from exercise of common stock warrants			$ 0
Purchase of common stock by underwriters to cover overallotments, number of shares		538,867
Subsequent Event [Member] \| Over-allotment Option [Member]
Subsequent Event [Line Items]
Issuance of warrants to purchase shares of common stock			937,500
Common Stock [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Shares issued in offering				990,000
Proceeds from issuance of common stock, net of issuance costs				$ 2,000,000
Beginning stock price				$ 2.25
Maximum [Member]
Subsequent Event [Line Items]
Issuance of warrants to purchase shares of common stock								1,095,153
Maximum [Member] \| Follow-on Public Offering [Member]
Subsequent Event [Line Items]
Issuance of warrants to purchase shares of common stock								1,095,153
Maximum [Member] \| Subsequent Event [Member] \| Follow-on Public Offering [Member]
Subsequent Event [Line Items]
Issuance of warrants to purchase shares of common stock			6,250,000
Maximum [Member] \| Subsequent Event [Member] \| Over-allotment Option [Member]
Subsequent Event [Line Items]
Issuance of warrants to purchase shares of common stock			937,500

Fair Value Measurements - Assumptions Used for Determining Fair Values of Common Stock Warrants (Detail)	Dec. 31, 2018 $ / shares	Sep. 20, 2018 $ / shares	Jan. 30, 2018 $ / shares
Warrant Fair Value Black Scholes Method [Line Items]
Beginning stock price		$ 3.285	$ 13.50
March 31, 2017 Offering [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Beginning stock price	$ 63.90
March 31, 2017 Offering [Member] \| Exercise Price [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	75.00
March 31, 2017 Offering [Member] \| Expected Dividend Yield [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	0.0000
March 31, 2017 Offering [Member] \| Discount Rate-Bond Equivalent Yield [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	0.0193
March 31, 2017 Offering [Member] \| Expected Life [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Expected life (in years)	5 years
March 31, 2017 Offering [Member] \| Expected Volatility [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	0.800
August 9, 2017 Offering [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Beginning stock price	$ 41.70
August 9, 2017 Offering [Member] \| Exercise Price [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	45.00
August 9, 2017 Offering [Member] \| Expected Dividend Yield [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	0.0000
August 9, 2017 Offering [Member] \| Discount Rate-Bond Equivalent Yield [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	0.0181
August 9, 2017 Offering [Member] \| Expected Life [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Expected life (in years)	5 years
August 9, 2017 Offering [Member] \| Expected Volatility [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	1.000
December 8, 2017 Offering [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Beginning stock price	$ 22.20
December 8, 2017 Offering [Member] \| Exercise Price [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	25.50
December 8, 2017 Offering [Member] \| Expected Dividend Yield [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	0.0000
December 8, 2017 Offering [Member] \| Discount Rate-Bond Equivalent Yield [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	0.0209
December 8, 2017 Offering [Member] \| Expected Life [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Expected life (in years)	4 years 6 months
December 8, 2017 Offering [Member] \| Expected Volatility [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	1.000
January 30, 2018 Offering [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Beginning stock price	$ 10.17
January 30, 2018 Offering [Member] \| Exercise Price [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	15.00
January 30, 2018 Offering [Member] \| Expected Dividend Yield [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	0.00
January 30, 2018 Offering [Member] \| Discount Rate-Bond Equivalent Yield [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	2.48
January 30, 2018 Offering [Member] \| Expected Life [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Expected life (in years)	5 years
January 30, 2018 Offering [Member] \| Expected Volatility [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	99.00
August 13, 2018 Rights Offering [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Beginning stock price	$ 3.89
August 13, 2018 Rights Offering [Member] \| Exercise Price [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	4.53
August 13, 2018 Rights Offering [Member] \| Expected Dividend Yield [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	0.00
August 13, 2018 Rights Offering [Member] \| Discount Rate-Bond Equivalent Yield [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	2.75
August 13, 2018 Rights Offering [Member] \| Expected Life [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Expected life (in years)	5 years
August 13, 2018 Rights Offering [Member] \| Expected Volatility [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	128.69
September 20, 2018 Offering [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Beginning stock price	$ 2.92
September 20, 2018 Offering [Member] \| Exercise Price [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	3.16
September 20, 2018 Offering [Member] \| Expected Dividend Yield [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	0.00
September 20, 2018 Offering [Member] \| Discount Rate-Bond Equivalent Yield [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	2.77
September 20, 2018 Offering [Member] \| Expected Life [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Expected life (in years)	5 years
September 20, 2018 Offering [Member] \| Expected Volatility [Member]
Warrant Fair Value Black Scholes Method [Line Items]
Exercise price	130.7

401(k) Plan - Additional Information (Detail) - USD ($)	12 Months Ended
401(k) Plan - Additional Information (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Postemployment Benefits [Abstract]
Employer's matching contributions to 401(k) plan	$ 215,000	$ 90,000