0001274737-21-000015 | 10-K | XBRL Viewer

Cover - USD ($) $ in Millions	12 Months Ended
Cover - USD ($) $ in Millions	Dec. 31, 2020	Mar. 12, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	001-39049
Entity Registrant Name	EXAGEN INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-0434866
Entity Address, Address Line One	1261 Liberty Way
Entity Address, City or Town	Vista
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92081
City Area Code	(760)
Local Phone Number	560-1501
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	XGN
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 83.4
Entity Common Stock, Shares Outstanding		12,669,816
Documents Incorporated by Reference	Certain information required to be disclosed in Part III of this report is incorporated by reference from the registrant's definitive Proxy Statement for the 2021 Annual Meeting of Stockholders, which proxy statement will be filed not later than 120 days after the end of the fiscal year covered by this Form 10-K.
Entity Central Index Key	0001274737
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 57,448	$ 72,084
Accounts receivable, net	8,910	5,715
Prepaid expenses and other current assets	4,159	3,451
Total current assets	70,517	81,250
Property and equipment, net	2,102	1,380
Goodwill	5,506	5,506
Other assets	250	174
Total assets	78,375	88,310
Current liabilities:
Accounts payable	3,014	1,476
Accrued and other current liabilities	5,757	4,419
Total current liabilities	8,771	5,895
Borrowings-non-current portion, net of discounts and debt issuance costs	26,659	25,854
Deferred tax liabilities	158	264
Other non-current liabilities	948	638
Total liabilities	36,536	32,651
Commitments and contingencies (Note 5)
Stockholders' equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized, no shares issued or outstanding at December 31, 2020 and December 31, 2019	0	0
Common stock, $0.001 par value; 200,000,000 shares authorized at December 31, 2020 and December 31, 2019; 12,652,308 and 12,560,990 shares issued and outstanding at December 31, 2020 and December 31, 2019, respectively	13	13
Additional paid-in capital	223,115	220,248
Accumulated deficit	(181,289)	(164,602)
Total stockholders' equity	41,839	55,659
Total liabilities and stockholders' equity	$ 78,375	$ 88,310

Balance Sheets - (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Preferred stock
Par value (in dollars per share)	$ 0.001	$ 0.001
Shares authorized (in shares)	10,000,000	10,000,000
Shares issued (in shares)	0	0
Shares outstanding (in shares)	0	0
Common stock
Par value (in dollars per share)	$ 0.001	$ 0.001
Shares authorized (in shares)	200,000,000	200,000,000
Shares issued (in shares)	12,652,308	12,560,990
Shares outstanding (in shares)	12,652,308	12,560,990

Statements of Operations - USD ($) $ in Thousands	12 Months Ended
Statements of Operations - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Revenue	$ 41,975	$ 40,387
Operating expenses:
Costs of revenue	16,559	18,808
Selling, general and administrative expenses	37,033	28,702
Research and development expenses	3,568	2,176
Total operating expenses	57,160	49,686
Loss from operations	(15,185)	(9,299)
Interest expense	(2,565)	(3,491)
Change in fair value of financial instruments	0	267
Other income, net	984	510
Loss before income taxes	(16,766)	(12,013)
Income tax benefit (expense)	79	(25)
Net loss	(16,687)	(12,038)
Accretion of redeemable convertible preferred stock	0	(4,640)
Deemed dividend recorded in connection with financing transactions	0	(13,601)
Net loss attributable to common stockholders	$ (16,687)	$ (30,279)
Net loss per share, basic and diluted (USD per share)	$ (1.32)	$ (8.46)
Weighted-average number of shares used to compute net loss per share, basic and diluted (in shares)	12,632,780	3,578,771

Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity - USD ($) $ in Thousands	Total	Series G redeemable convertible preferred stock	Series H redeemable convertible preferred stock	Common Stock	Additional Paid-In Capital	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2018	532,606,084
Beginning balance at Dec. 31, 2018	$ 105,232
Increase (Decrease) in Temporary Equity [Roll Forward]
Accretion of redeemable convertible preferred stock	4,640
Issuance of Series redeemable convertible preferred stock for aggregate proceeds, net of issuance costs (in shares)		148,928,337	233,446,519
Issuance of Series redeemable convertible preferred stock for aggregate proceeds, net of issuance costs		$ 11,492	$ 3,941
Deemed dividend recognized on beneficial conversion features of Series H redeemable convertible preferred stock (Note 7)	$ 6,741		6,741
Deemed dividend from conversion of Series G to Series H redeemable convertible preferred stock (Note 7) (in shares)	97,592,739
Deemed dividend from conversion of Series G to Series H redeemable convertible preferred stock (Note 7)	$ 6,860
Conversion of preferred stock to common stock in connection with initial public offering (in shares)	(1,012,573,679)
Conversion of preferred stock to common stock in connection with initial public offering (Note 7)	$ (138,906)
Ending balance (in shares) at Dec. 31, 2019	0
Ending balance at Dec. 31, 2019	$ 0
Beginning balance (in shares) at Dec. 31, 2018				63,005
Beginning balance at Dec. 31, 2018	(111,966)			$ 0	$ 40,598	$ (152,564)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of redeemable convertible preferred stock	(4,640)				(4,640)
Exercise of stock options (in shares)				1,548
Exercise of stock options	4				4
Stock-based compensation	572				572
Issuance of Series H redeemable convertible preferred stock for aggregate proceeds of $0.047 per share, net of issuance costs of $318 (Note 7)	6,741				6,741
Deemed dividend recognized on beneficial conversion features of Series H redeemable convertible preferred stock (Note 7)	(6,741)				(6,741)
Deemed dividend from conversion of Series G to Series H redeemable convertible preferred stock (Note 7)	(6,860)				(6,860)
Conversion of preferred stock to common stock in connection with initial public offering (Noted 7) (in shares)				7,816,643
Conversion of preferred stock to common stock in connection with initial public offering (Note 7)	138,906			$ 8	138,898
Issuance of common stock in initial public offering, net of underwriting discount, commissions and issuance costs (Note 8) (in shares)				4,140,000
Issuance of common stock in initial public offering, net of underwriting discount, commissions and issuance costs (Note 8)	50,444			$ 4	50,440
Net exercise of common and preferred stock warrants (in shares)				539,794
Net exercise of common and preferred stock warrants	511			$ 1	510
Reclassification of redeemable convertible preferred stock warrant liabilities as equity	726				726
Net loss	$ (12,038)					(12,038)
Ending balance (in shares) at Dec. 31, 2019	12,560,990			12,560,990
Ending balance at Dec. 31, 2019	$ 55,659			$ 13	220,248	(164,602)
Increase (Decrease) in Temporary Equity [Roll Forward]
Accretion of redeemable convertible preferred stock	$ 0
Deemed dividend recognized on beneficial conversion features of Series H redeemable convertible preferred stock (Note 7)			$ 0
Ending balance (in shares) at Dec. 31, 2020	0
Ending balance at Dec. 31, 2020	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)	47,549			47,549
Exercise of stock options	$ 13				13
Stock-based compensation	2,694				2,694
Net exercise of common and preferred stock warrants (in shares)				32,120
Net exercise of common and preferred stock warrants	18				18
Issuance of stock under Employee Stock Purchase Plan (in shares)				11,649
Issuance of stock under Employee Stock Purchase Plan	142				142
Net loss	$ (16,687)					(16,687)
Ending balance (in shares) at Dec. 31, 2020	12,652,308			12,652,308
Ending balance at Dec. 31, 2020	$ 41,839			$ 13	$ 223,115	$ (181,289)

Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares
Series G redeemable convertible preferred stock
Sale of temporary equity, price per share (in dollars per share) \| $ / shares	$ 0.078
Issuance costs \| $	$ 124
Series H redeemable convertible preferred stock
Sale of temporary equity, price per share (in dollars per share) \| $ / shares	$ 0.047
Issuance costs \| $	$ 318

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (16,687)	$ (12,038)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	546	591
Amortization of debt discount and debt issuance costs	274	691
Non-cash interest expense	531	546
Revaluation of warrant liabilities	0	(267)
Deferred income taxes	(106)	0
Loss on disposal of assets	0	20
Stock-based compensation	2,694	572
Changes in assets and liabilities:
Accounts receivable, net	(3,195)	237
Prepaid expenses and other current assets	(708)	(1,255)
Other assets	(15)	(24)
Accounts payable	986	528
Accrued and other current liabilities	1,596	688
Net cash used in operating activities	(14,084)	(9,711)
Cash flows from investing activities:
Purchases of property and equipment	(455)	(403)
Proceeds from sale of property and equipment	0	300
Net cash used in investing activities	(455)	(103)
Cash flows from financing activities:
Proceeds from sale of common stock upon exercise of stock options	13	4
Proceeds from common stock issued under Employee Stock Purchase Plan	142	0
Proceeds from exercise of common stock warrants	18	0
Principal payment on capital lease obligations	(249)	(138)
Proceeds from Paycheck Protection Program loan	2,865	0
Repayment of Paycheck Protection Program loan	(2,865)	0
Proceeds from initial public offering, net of issuance costs and offering costs	0	50,444
Payments of deferred offering costs	(21)	0
Net cash (used in) provided by financing activities	(97)	68,734
Net change in cash, cash equivalents and restricted cash	(14,636)	58,920
Cash, cash equivalents and restricted cash, beginning of period	72,184	13,264
Cash, cash equivalents and restricted cash, end of period	57,548	72,184
Supplemental disclosure of cash flow information:
Cash paid for interest expense	1,758	2,288
Supplemental disclosure of non-cash items:
Accretion to redemption value of redeemable convertible preferred stock	0	4,640
Equipment purchased under capital lease obligations	260	654
Costs incurred, but not paid, in connection with capital expenditures	553	0
Conversion of redeemable convertible preferred stock	0	138,906
Net exercise of common and preferred stock warrants	0	511
Deferred offering costs included in accounts payable and accrued and other current liabilities	40	0
Reclassification of redeemable convertible preferred stock warrant liabilities as equity	0	726
Deemed dividend recognized for beneficial conversion features of Series H redeemable convertible preferred stock		6,741
Series G redeemable convertible preferred stock
Cash flows from financing activities:
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs	0	7,742
Supplemental disclosure of non-cash items:
Deemed dividend from conversion of Series G to Series H redeemable convertible preferred stock	0	6,860
Conversion of Series G to Series H redeemable convertible preferred stock	0	11,875
Series H redeemable convertible preferred stock
Cash flows from financing activities:
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs	0	10,682
Supplemental disclosure of non-cash items:
Deemed dividend recognized for beneficial conversion features of Series H redeemable convertible preferred stock	$ 0	$ 6,741

Organization	12 Months Ended
Organization	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Description of Business The Company is dedicated to transforming the care continuum for patients suffering from debilitating and chronic autoimmune diseases by enabling timely differential diagnosis and optimizing therapeutic intervention. Liquidity The Company has incurred recurring losses and negative cash flows from operating activities since inception. The Company anticipates that it will continue to incur net losses into the foreseeable future. At December 31, 2020, the Company had cash and cash equivalents of $57.4 million and had an accumulated deficit of $181.3 million. Since inception, the Company has financed its operations primarily through private placements of preferred securities, the sale of common stock through its initial public offering (IPO) and debt financing arrangements. Based on the Company's current business plan, management believes that its existing capital resources will be sufficient to fund the Company's obligations for at least twelve months following the issuance of these financial statements. To execute its business plans, the Company may need additional funding to support its continuing operations and pursue its growth strategy. Until such time as the Company can achieve significant cash flows from operations, if ever, it expects to finance its operations through the sale of its stock, debt financings or other strategic transactions. Although the Company has been successful in raising capital in the past, there is no assurance that it will be successful in obtaining such additional financing on terms acceptable to the Company, if at all. The terms of any financing may adversely affect the holdings or the rights of the Company's stockholders. If the Company is unable to obtain funding, the Company could be forced to delay, reduce or eliminate some or all of its programs, product portfolio expansion plans or commercialization efforts, which could have a material adverse effect on the Company's business, operating results and financial condition and the Company's ability to achieve its intended business objectives.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Summary Of Significant Accounting Policies

Summary of Significant Accounting Policies

Basis of Presentation and Use of Estimates

The Company's financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (GAAP). The preparation of the accompanying financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities as of the date of the financial statements, and the reported amounts of revenue and expenses during the reporting period. Actual results could materially differ from those estimates.

Significant estimates and assumptions made in the accompanying financial statements include, but are not limited to revenue recognition, the fair value of financial instruments measured at fair value, the recoverability of its long-lived assets (including goodwill), net deferred tax assets (and related valuation allowance), and for periods prior to the IPO, the fair value of the Company's common stock and redeemable convertible preferred stock. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could materially differ from those estimates.

Concentration of Credit Risk and Other Risk and Uncertainties

Financial instruments that potentially subject the Company to credit risk consist principally of cash, cash equivalents, and accounts receivable. Substantially all the Company's cash and cash equivalents are held at one financial institution that management believes is of high credit quality. Such deposits may, at times, exceed federally insured limits.

Significant payors and customers are those which represent more than 10% of the Company's total revenue or accounts receivable balance at each respective balance sheet date. For each significant payor and customers, revenue as a percentage of total revenue and accounts receivable as a percentage of total accounts receivable are as follows:


		Revenue
	Years Ended December 31,
			2020		2019
Medicare			20	%	25	%
Janssen (SIMPONI®)			12	%	*
Blue Shield			11	%	12	%
Medicare Advantage			11	%	11	%
United Healthcare			*		11	%



*						Less than 10%.


	Accounts Receivable
	December 31,
	2020		2019
Janssen (SIMPONI®)	35	%	19	%
Blue Shield	11	%	15	%
United Healthcare	*		22	%



*						Less than 10%.

For the years ended December 31, 2020 and 2019, approximately 70% and 82% of the Company's revenue was related to the AVISE® CTD test, respectively.

The Company is dependent on key suppliers for certain laboratory materials. For each of the years ended December 31, 2020 and 2019, approximately 97% of the Company's diagnostic testing supplies were purchased from two suppliers. An interruption in the supply of these materials would impact the Company's ability to perform testing services.

Disaggregation of Revenue

The following table includes the Company's revenues as disaggregated by payor and customer category (in thousands):


	Years Ended December 31,
		2020		2019
Revenue:
Healthcare insurers		$	22,456	$	23,984
Government		8,446		9,896
Client(1)		5,109		4,392
Other(2)		836		639
Janssen (SIMPONI®)		5,128		1,476
Total revenue		$	41,975	$	40,387

(1)Includes hospitals, other laboratories, etc.

(2)Includes patient self-pay that is immaterial.

Fair Value Measurements

The carrying value of the Company's cash and cash equivalents approximate fair value due to the short-term nature of these items. Based on the borrowing rates currently available to the Company for debt with similar terms and consideration of default and credit risk, the carrying value of the Company's long-term borrowings approximates its fair value, which is considered a Level 2 input.

Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs.

The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows:

Level 1 - Unadjusted quoted prices in active markets for identical assets or liabilities;

Level 2 - Inputs other than quoted prices included within Level I that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and

Level 3 - Unobservable inputs that are supported by little or no market activity for the related assets or liabilities.

The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.

Prior to the IPO, the Company's redeemable convertible preferred stock warrant liabilities were measured at fair value on a recurring basis and were classified as Level 3 liabilities. The Company recorded subsequent adjustments to reflect the increase or decrease in estimated fair value at each reporting date in current period earnings.

Cash, Cash Equivalents and Restricted Cash

The Company considers all highly-liquid investments purchased with a remaining maturity date upon acquisition of three months or less to be cash equivalents and are stated at cost, which approximates fair value.

In 2016, the Company entered into an arrangement with a financial institution with which it has an existing banking relationship whereby in exchange for the issuance of corporate credit cards, the Company agreed to obtain a $0.1 million certificate of deposit with this financial institution as collateral for the balances borrowed on these credit cards. The Company has classified the value of this certificate of deposit (including all interest earned thereon) within other assets in the accompanying balance sheets. The Company has the right to terminate the credit card program at any time. Upon termination of the credit card program and repayment of all outstanding balances owed, the Company may redeem the certificate of deposit (and all interest earned thereon).

Cash, cash equivalents and restricted cash presented in the accompanying statements of cash flows consist of the following (in thousands):


		December 31,
	2020	2019
Cash and cash equivalents		$	57,448	$	72,084
Restricted cash		100		100
		$	57,548	$	72,184

Property and Equipment

Property and equipment are stated at cost, net of depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, generally between three and five years. Leasehold improvements are amortized on a straight-line basis over the lesser of the estimated useful life or the remaining term of the related lease. Maintenance and repairs are charged to expense as incurred, and improvements and betterments are capitalized. When assets are retired or otherwise disposed of, the cost and

accumulated depreciation are removed from the balance sheet and any resulting gain or loss is reflected in other income or expense in the statements of operations in the period realized.

Long-lived Assets

The Company’s long-lived assets are comprised principally of its property and equipment, finite lived intangible assets, and goodwill.

If the Company identifies a change in the circumstances related to its long-lived assets, such as property and equipment and intangible assets (other than goodwill), that indicates the carrying value of any such asset may not be recoverable, the Company will perform an impairment analysis. A long-lived asset (other than goodwill) is deemed to be impaired when the undiscounted cash flows expected to be generated by the asset (or asset group) are less than the asset’s carrying amount. Any required impairment loss would be measured as the amount by which the asset’s carrying value exceeds its fair value, and would be recorded as a reduction in the carrying value of the related asset and a charge to operating expense.

Goodwill is reviewed for impairment annually (during the fourth quarter) or more frequently if indicators of impairment exist. As the Company operates in a single operating segment and reporting unit, the Company first assesses qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit is less than its carrying amount as a basis for determining whether it is necessary to perform a quantitative assessment. If, after assessing qualitative factors, the Company determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then performing a quantitative assessment is unnecessary. If deemed necessary, a quantitative assessment compares the fair value of the reporting unit with its carrying amount, including goodwill. If the fair value of the reporting unit exceeds its carrying amount, goodwill is not considered impaired; otherwise, an impairment loss is recorded. There was no indication of impairment of goodwill for any periods presented.

Clinical Studies

From time to time, the Company engages in efforts to scientifically measure and document the application and efficacy of its various testing products. These arrangements typically require the Company to pay a fee to a third-party scientific investigator (usually a physician or research institution) for each subject enrolled in a clinical study, and the Company accrues expenses associated with these efforts as subjects are enrolled in each study. Expenses associated with clinical study activities are recorded in research and development expenses in the accompanying statement of operations.

Redeemable Convertible Preferred Stock

Prior to the completion of the IPO, the Company had multiple classes of redeemable convertible preferred stock, all of which were classified as temporary equity in the accompanying balance sheet as the redemption of the shares were outside of the Company's control. Redeemable convertible preferred stock which was redeemable on or after a certain date at the option of the holder was accreted to its redemption value from the date of issuance to the earliest redemption date.

In connection with the completion of the IPO in September 2019, all outstanding shares of redeemable convertible preferred stock were automatically converted into an aggregate of 7,816,643 shares of common stock, excluding warrant conversions.

Redeemable Convertible Preferred Stock Warrants

Prior to the completion of the IPO, the Company accounted for its redeemable convertible preferred stock warrants as liabilities based upon the characteristics and provisions of each instrument. The redeemable convertible preferred stock warrants were recorded at their fair value on the date of issuance and were revalued on each subsequent balance sheet date, with fair value changes recognized as increases or reductions in the statements of operations. Upon the completion of the IPO, all remaining outstanding warrants to purchase shares of redeemable convertible preferred stock were automatically converted into warrants to purchase shares of common stock. As such, the warrants no longer require liability accounting and the then fair value of the warrant liability was reclassified into stockholders’ equity.

The Company performed the final remeasurement of the warrant liabilities as of the IPO closing date. See Note 7 for the amounts associated with the fair value measurements and Note 8 for further discussion on the remaining warrants.

Revenue Recognition

Substantially all of the Company's revenue has been derived from sales of its testing products and is primarily comprised of a high volume of relatively low-dollar transactions. The Company primarily markets its testing products to rheumatologists and their physician assistants in the United States. The healthcare professionals who order the Company's testing products and to whom test results are reported are generally not responsible for payment for these products. The parties that pay for these services (the Payors) consist of healthcare insurers, government payors (primarily Medicare and Medicaid), client payors (i.e., hospitals, other laboratories, etc.), and patient self-pay. The Company's service is a single performance obligation that is completed upon the delivery of test results to the prescribing physician which triggers revenue recognition.

Payors are billed at the Company's list price. Net revenues recognized consist of amounts billed net of allowances for differences between amounts billed and the estimated consideration the Company expects to receive from such payors. The process for estimating revenues and the ultimate collection of accounts receivable involves significant judgment and estimation. The Company follows a standard process, which considers historical denial and collection experience, insurance reimbursement policies and other factors, to estimate allowances and implicit price concessions, recording adjustments in the current period as changes in estimates occur. Further adjustments to the allowances, based on actual receipts, is recorded upon settlement. The transaction price is estimated using an expected value method on a portfolio basis. The Company's portfolios are grouped per payor (i.e. each individual third-party insurance, Medicare, client payors, patient self-pay, etc.) and per test basis.

Collection of the Company's net revenues from payors is normally a function of providing complete and correct billing information to the healthcare insurers and generally occurs within 30 to 90 days of billing. Contracts do not contain significant financing components based on the typical period of time between performance of services and collection of consideration.

Janssen Promotion Agreement

In December 2018, the Company entered into a co-promotion agreement (the Janssen Agreement) with Janssen Biotech, Inc. (Janssen) to co-promote SIMPONI® in the United States. The Company is responsible for the costs associated with its salesforce over the course of such co-promotion. Janssen is responsible for all other aspects of the commercialization of SIMPONI® under the Janssen Agreement. In exchange for the Company's sales and co-promotional services, the Company is entitled to a quarterly tiered promotion fee based on the incremental increase in total prescribed units of SIMPONI® for that quarter over a predetermined baseline. For the years ended December 31, 2020 and 2019, the tiered promotion fee ranged from $750 to $1,250 per prescription over a predetermined baseline. Due in part to COVID-19, in June 2020, the Janssen Agreement was amended (June Amended Janssen Agreement). In accordance with the June Amended Janssen Agreement, the predetermined average baseline for prescribed units for each remaining quarter in 2020 was adjusted and is subject to further adjustment, and for each of the third and fourth quarters of 2020, the Company received a minimum promotion fee of $0.3 million and the fee was capped at 5% above the adjusted predetermined baseline. In December 2020, the Janssen Agreement amended. The Janssen Agreement, as amended in June 2020 and December 2020 is collectively referred to as the Amended Janssen Agreement. In accordance with the Amended Janssen Agreement, the predetermined average baseline for prescribed units for the quarters ending December 31, 2020, March 31, 2021 and June 30, 2021, was adjusted to approximately 28,750 prescribed units per quarter, subject to adjustment under certain circumstances. For the first and second quarters of 2021, the Company will be entitled to an amended tiered promotion fee ranging from $500 to $1,000 per prescription based on the incremental increase in total prescribed units. Pursuant to the Amended Janssen Agreement, for the first and second quarters of 2021, the Company will receive a minimum promotion fee of $0.3 million and the fee will be capped at 10% above the adjusted predetermined baseline. The Company continued to receive a minimum promotion fee of $0.3 million and the fee was capped at 5% above the adjusted predetermined baseline for the quarter ended December 31, 2020. The quarterly tiered promotion fee for the remaining term of the Janssen Promotion Agreement beginning with the quarter ended September 30, 2021 will revert to the terms set forth in the Janssen Agreement prior to amendment, with no minimum promotion fee and no cap on predetermined baseline units. In addition, during the term of the Janssen Agreement, the Company is restricted from promoting any other biologic or Janus kinase inhibitor, or JAK inhibitor, used for treatment of indications covered by the agreement without first obtaining Janssen's written consent.

The Janssen Agreement expires on December 31, 2021, unless extended by the Company for an additional 12 months upon 180 days written notice prior to the end of the current term. If the Company elects to extend the term, the predetermined baseline for 2022 will be subject to future agreement by the Company and Janssen. Janssen may terminate the Amended Janssen Agreement at any time for any reason upon 30 days' notice to the Company, and the Company may terminate the Amended Janssen Agreement for any reason at the end of any calendar quarter upon 30 days' notice to Janssen. Either party may terminate the Amended Janssen Agreement in the event of the other party's default of any of its material obligations under the agreement if such default remains uncured for a specified period of time following receipt of written notice of such default.

The Company's obligations relating to sales and co-promotion services for SIMPONI® is a series of single performance obligations since Janssen simultaneously receives and consumes benefits provided by the Company's sales and co-promotional services. The method for measuring progress towards satisfying the performance obligations is based on prescribed units in excess of the contractual baseline at the contractual rate earned per unit since the agreement is cancelable. The Company recognized co-promotion revenue of approximately $5.1 million and $1.5 million during the years ended December 31, 2020 and 2019, respectively. The related expenses for marketing SIMPONI® are included in selling, general and administrative expenses and are expensed as incurred.

Research and Development

Costs associated with research and development activities are expensed as incurred and include, but are not limited to, personnel-related expenses, including stock-based compensation expense, materials, laboratory supplies, consulting costs, costs associated with setting up and conducting clinical studies and allocated overhead including rent and utilities.

Advertising and Marketing Costs

Costs associated with advertising and marketing activities are expensed as incurred. Total advertising and marketing costs were approximately $1.3 million and $1.6 million for the years ended December 31, 2020 and 2019, respectively, and are included in selling, general and administrative expenses in the accompanying statements of operations.

Shipping and Handling Costs

Costs incurred for shipping and handling are included in costs of revenue in the accompanying statements of operations and totaled approximately $1.4 million for each of the years ended December 31, 2020 and 2019.

Stock-Based Compensation

The Company recognizes compensation expense for all stock-based awards to employees and directors based on the grant-date estimated fair values over the requisite service period of the awards (usually the vesting period) on a straight-line basis. The fair value of stock options and purchases under the employee stock purchase plan (ESPP) rights is determined using the Black-Scholes-Merton (BSM) option pricing model, which requires management to make certain assumptions regarding a number of complex and subjective variables. Equity award forfeitures are recorded as they occur.

The BSM option pricing model incorporates various estimates, including the fair value of the Company's common stock, expected volatility, expected term and risk-free interest rates. The weighted-average expected term of options was calculated using the simplified method. This decision was based on the lack of relevant historical data due to the Company's limited historical experience. In addition, due to the Company's limited historical data, the estimated volatility incorporates the historical volatility over the expected term of the award of comparable companies whose share prices are publicly available. The risk-free interest rate for periods within the contractual term of the option is based on the U.S. Treasury yield in effect at the time of grant. The dividend yield was zero, as the Company has never declared or paid dividends and has no plans to do so in the foreseeable future.

Upon the effective date of the IPO, the Company began using the closing price of its common stock as the fair value of its common stock on the corresponding date. Prior to the completion of the IPO in September 2019, due to the absence of a public market for the Company's common stock, it was necessary to estimate the fair value of the common stock underlying the Company's stock-based awards when performing fair value calculations using the BSM option pricing model. The fair value of the common stock underlying the Company's stock-based awards was assessed on each grant date by the Company's board of directors (Board of Directors).

Comprehensive Loss

Comprehensive loss is defined as a change in equity of a business enterprise during a period, resulting from transactions from nonowner sources. There have been no items qualifying as other comprehensive loss and, therefore, for all periods presented, the Company's comprehensive loss was the same as its reported net loss.

Income Taxes

The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date.

The Company recognizes net deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would adjust the deferred tax asset valuation allowance, which would reduce the provision for income taxes.

The Company records uncertain tax positions on the basis of a two-step process whereby (i) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (ii) for those tax positions that meet the more-likely-than-not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50% likely to be realized upon ultimate settlement with the related tax authority. The Company recognizes interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability.

Net Loss Per Share

Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. Potentially dilutive common stock equivalents are comprised of redeemable convertible preferred stock, warrants for the purchase of redeemable convertible preferred and common stock, options outstanding under the Company's stock option plans and shares of the Company's common stock pursuant to Employee Stock Purchase Plan. For the years ended December 31, 2020 and 2019, there is no difference in the number of shares used to calculate basic and diluted shares outstanding as the inclusion of the potentially dilutive securities would be antidilutive.

Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common stock equivalent shares):


	Years Ended December 31,
		2020	2019


Warrants to purchase common stock		426,827	461,273
Common stock options		1,975,761	1,375,542
Employee stock purchase plan		11,640	—
Total		2,414,228	1,836,815

Government Assistance Grant Income

Government assistance grants which are unconditional when received and intended to compensate for expenses incurred or replace lost revenue are recognized when those expenses are incurred or during the period that lost revenue is experienced, and are included in other income, net in the accompanying statements of operations.

Segment Reporting

Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations as, and manages its business in, one operating segment.

Recent Accounting Pronouncements Not Yet Adopted

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (FASB), or other standard setting bodies and adopted by the Company as of the specified effective date. Under the Jumpstart Our Business Startups Act of 2012 (JOBS Act), the Company meets the definition of an emerging growth company. The Company has elected to use the extended transition period for complying with new or revised accounting standards pursuant to Section 107(b) of the JOBS Act. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company's financial position or results of operations upon adoption.

In February 2016, the FASB issued Accounting Standards Update (ASU) 2016-02, Leases (Topic 842). The new topic supersedes Topic 840, Leases, and increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and requires disclosures of key information about leasing arrangements. In July 2018, the FASB issued ASU 2018-10, Codification Improvements to Topic 842, which provides narrow amendments to clarify how to apply certain aspects of the new lease standard, and ASU 2018-11, Leases: Targeted Improvements, which was issued to provide relief to companies from restating comparative periods. Pursuant to this ASU, in the period of adoption the Company will not restate comparative periods presented in its financial statements. The effective date of this guidance for public companies is for reporting periods beginning after December 15, 2018. In June 2020, the FASB issued ASU 2020-05, which delays the adoption of ASU 2016-02 for non-public entities to fiscal years beginning after December 15, 2021, and interim periods beginning after December 15, 2022. As an emerging growth company as defined in the JOBS Act, the Company has elected to delay adoption of this ASU until January 1, 2022. Topic 842 mandates a modified retrospective transition method. The Company intends to adopt the new lease standard using a cumulative effect to accumulated deficit and will elect the package of practical expedients, which among other things will allow the Company to carry forward its historical lease classification. The Company is currently evaluating the impact of Topic 842 on its financial statements.

In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes. The new guidance removes certain exceptions to the general principles of ASC 740 in order to simplify the complexities of its application. These changes include eliminations to the exceptions for intraperiod tax allocation, recognizing deferred tax liabilities related to outside basis differences, and year-to-date losses in interim periods, among others. The effective date of this guidance for public companies is for fiscal years, and interim period within those fiscal years, beginning after December 15, 2020. The Company does not anticipate the adoption will have a material impact on its financial statements.

Recently Adopted Accounting Standards

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement: Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement, which adds and modifies certain disclosure requirements for fair value measurements. Under the new guidance, entities will no longer be required to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, or valuation processes for Level 3 fair value measurements. However, public companies will be required to disclose the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and related changes in unrealized gains and losses included in other comprehensive income. The narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. This update is effective for annual periods beginning after December 15, 2019, and interim periods within those periods, and early adoption is permitted. The Company adopted this guidance on January 1, 2020, and the adoption did not have a material impact on its financial statements.

Other Financial Information

12 Months Ended

Dec. 31, 2020

Other Financial Information [Abstract]

Other Financial Information

Other Financial InformationPrepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following (in thousands):


	December 31,
	2020		2019
Diagnostic testing supplies	$	1,203	$	1,427
Prepaid product royalties	68		123
Prepaid maintenance and insurance contracts	2,229		1,768
Other prepaid and other current assets	659		133
Prepaid and other current assets	$	4,159	$	3,451

Property and Equipment

Property and equipment consist of the following (in thousands):


	December 31,
	2020		2019
Furniture and fixtures	$	64	$	25
Laboratory equipment	2,679		2,228
Computer equipment and software	927		851
Leasehold improvements	1,072		424
Construction in progress	301		247
Total property and equipment	5,043		3,775
Less: accumulated depreciation and amortization	(2,941)		(2,395)
Property and equipment, net	$	2,102	$	1,380

Depreciation and amortization expense for the years ended December 31, 2020 and 2019, was approximately $0.5 million and $0.6 million, respectively. At December 31, 2020 and December 31, 2019, the gross book value of assets under capital lease was $1.2 million and $0.8 million, respectively, and is classified in "Laboratory equipment" in the table above.

Accrued and Other Current Liabilities

Accrued and other current liabilities consist of the following (in thousands):


	December 31,
	2020		2019
Accrued payroll and related expenses	$	3,589	$	2,362

Accrued interest	147		145
Accrued purchases of goods and services	311		319
Accrued royalties	221		727
Accrued clinical study activity	228		40
Capital lease obligations, current portion	308		238
Other accrued liabilities	953		588
Accrued and other current liabilities	$	5,757	$	4,419

Borrowings

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Borrowings

Borrowings2017 Term Loan

In September 2017, the Company executed a term loan agreement (the 2017 Term Loan) with Innovatus Life Sciences Lending Fund I, LP (Innovatus) and borrowed $20.0 million, $17.8 million of which was immediately used to repay the Company's existing loan with Capital Royalty Partners II L.P. and its affiliates. On December 7, 2018, the Company borrowed an additional $5.0 million under the 2017 Term Loan. At December 31, 2020, no additional amounts remain available to borrow under the 2017 Term Loan.

In November 2019, the Company executed the First Amendment to the Loan and Security Agreement (the 2017 Loan Amendment). The interest rate on all borrowings under the Loan Amendment is 8.5%, of which 2.0% is paid in-kind in the form of additional term loans (PIK Loans) until December of 2022, after which interest accrues at an annual rate of 8.5%. The Company has estimated the effective interest rate of this loan to be approximately 10%. Accrued interest is due and payable monthly, unless the Company elects to pay paid-in-kind interest. The outstanding principal and accrued interest on the Loan Amendment will be repaid in twenty-four equal monthly installments commencing in December 2022. Upon repayment of the final installment under the Loan Amendment, the Company is required to pay an additional fee of $1.0 million. This obligation is being accreted into interest expense over the term of Loan Amendment using the effective interest method. For each of the years ended December 31, 2020 and 2019, the Company issued PIK Loans totaling $0.5 million.

The Loan Amendment requires a prepayment premium of 3% of the aggregate outstanding principal. The prepayment premium decreases by 1% during each subsequent twelve-month period after November 19, 2020.

The Loan Amendment is collateralized by a first priority security interest on substantially all of the Company's assets, including intellectual property. The affirmative covenants of the Loan Amendment require that the Company timely file taxes, maintain good standing and government compliance, maintain liability and other insurance, provide prompt notification of significant corporate events, and furnish audited financial statements within 150 days of fiscal year end without qualification as to the scope of the audit or as to going concern and without any other similar qualification.

The affirmative covenants require that the Company achieve a specified level of revenue, as measured quarterly on a rolling twelve-month basis, and commencing with the quarter ending December 31, 2019. The consequences of failing to achieve the performance covenant may be cured if, within sixty days of failing to achieve the performance covenant, the Company issues additional equity securities or subordinated debt with net proceeds sufficient to fund any cash flow deficiency generated from operations, as defined. The Company's revenues for the twelve-month ended September 30, 2020 were lower than the specified targets, as a result, the Company and Innovatus agreed on a new management plan and target to bring the Company back into compliance with the Loan Amendment. The Loan Amendment requires that the Company maintain certain levels of minimum liquidity. The Company is required to maintain an unrestricted cash balance of $2.0 million.

The negative covenants provide, among other things, that without the prior consent of Innovatus subject to certain exceptions, the Company may not dispose of certain assets, engage in certain business combinations or acquisitions, incur additional indebtedness or encumber any of the Company's property, pay dividends on the Company's capital stock or make prohibited investments. The Loan Amendment agreement provides that an event of default will occur if, among other triggers, (i) the Company defaults in the payment of any amount payable under the agreement when due, (ii) there occurs any circumstance(s) that could reasonably be expected to result in a material adverse effect on the Company's business, operations or condition, or on the Company's ability to perform its obligations under the agreement, (iii) the Company becomes insolvent, (iv) the Company undergoes a change in control or (v) the Company breaches any negative covenants or certain affirmative covenants in the agreement or, subject to a cure period, otherwise neglects to perform or observe any material item in the agreement.

At December 31, 2020, the Company was in compliance with all covenants of the Loan Amendment.

Upon an event of default in any of the Loan Amendment covenants, the repayment of the Loan Amendment may be accelerated and the applicable interest rate will be increased by 4.0% until the default is cured. Although repayment of the Loan Amendment can be accelerated under certain circumstances, the Company believes acceleration of this loan is not probable as of the date of these financial statements. Accordingly, the Company has reflected the amounts of the Loan Amendment due beyond twelve months of the balance sheet date as non-current.

Future Minimum Payments on the Outstanding Borrowings

As of December 31, 2020, future minimum aggregate payments, including interest, for outstanding borrowings under the Loan Amendment are as follows (in thousands):


	Years Ending December 31,


2021	$	1,755
2022	2,996
2023	15,619
2024	14,280
Total	34,650
Less:
Unamortized debt discount and issuance costs	(296)
Interest	(7,695)
Total borrowings, net of discounts and debt issuance costs	$	26,659

Commitment and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Leases

As of December 31, 2020, the Company leases office and laboratory space in Vista, California, under leases that expire in January 2026, with an option to extend a portion of the lease for an additional 5-year period. In addition, the Company also leases additional office space in Vista, California, under a lease that expires in January 2026 with an option to extend the lease for an additional 5-year period. The Company's lease payments under each of these leases are subject to escalation clauses.

Minimum annual lease payments under non-cancelable lease arrangements at December 31, 2020 are as follows (in thousands):


Years Ending December 31,	Capital Leases		Operating Leases
2021	$	344	$	590
2022	318		613
2023	231		626
2024	58		640
2025	—		654
Thereafter	—		55
Total minimum lease payments	951		$	3,178
Less: amount representing interest	(67)
Present value of future minimum lease payments	884
Less: current portion	(308)
Long-term capital lease obligations	$	576

For the years ended December 31, 2020 and 2019, rent expense was $0.6 million and $0.5 million, respectively.

Acquisition-related liabilities

In connection with the acquisition of the medical diagnostics division of Cypress Bioscience, Inc. in 2010, the Company was required to pay certain amounts in the event that certain revenue milestones were achieved and upon the first commercial sale of a product associated with this acquisition. The acquisition also included amounts that may be due under several licensing agreements. All milestone payments other than one have been paid as of December 31, 2017. The remaining milestone obligation is for an additional $2.0 million payment due to Prometheus Laboratories, Inc. (Prometheus) for which the fair value was determined to be zero at December 31, 2020 and 2019.

In addition, the Company has ongoing royalty payment obligations on net sales of products which incorporate certain acquired technologies of 2.5%. Future royalties payable under these arrangements are limited to the lesser

of an aggregate of $1.2 million (including an upfront payment of $100,000) or the total royalties earned through January 1, 2024.

Licensing Agreements

The Company has licensed technology for use in its diagnostic tests. In addition to the milestone payments required by these agreements as described above, individual license agreements generally provide for ongoing royalty payments on net sales of products which incorporate licensed technology, as defined, ranging from 2.0% to 3.0%. Royalties are accrued when earned and recorded in costs of revenue in the accompanying statement of operations.

Supply Agreement

In September 2020, the Company entered into an amended supply agreement with one supplier for reagents which includes minimum annual purchase commitments of $4.1 million and $6.0 million for years ended December 31, 2021 and 2022, respectively, with a 15% annual increase thereafter through the year ended December 31, 2025.

Contingencies

In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications; including subpoenas and other civil investigative demands, from governmental agencies, Medicare or Medicaid payors and managed care organizations reviewing billing practices or requesting comment on allegations of billing irregularities that are brought to their attention through billing audits or third parties. The Company's exposure under these agreements is unknown because it involves claims that may be made against the Company in the future, but have not yet been made or of which of the Company believes to be immaterial. The Company accrues a liability for such matters when it is probable that future expenditures will be made and such expenditures can be reasonably estimated.

Litigation

From time to time, the Company may be subject to various legal proceedings that arise in the ordinary course of business activities.

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

The following table sets forth the Company's financial instruments that were measured at fair value on a recurring basis within the fair value hierarchy (in thousands):


	December 31, 2020
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds	$	34,507	$	34,507	$	—	$	—


	December 31, 2019
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds	$	70,760	$	70,760	$	—	$	—

The fair value of the Company's money market funds is based on quoted market prices.

- 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

Redeemable Convertible Preferred Stock	12 Months Ended
Redeemable Convertible Preferred Stock	Dec. 31, 2020
Temporary Equity Disclosure [Abstract]
Redeemable Convertible Preferred Stock	Redeemable Convertible Preferred Stock Series G Financing In January 2019, the Company entered into an agreement with new and certain existing preferred stockholders to issue shares of Series G redeemable convertible preferred stock in multiple separate closings at a per share price of $0.078 in each closing. In conjunction with the issuance of the Series H redeemable convertible preferred stock, each share of issued and outstanding Series G redeemable convertible preferred stock was converted into shares of Series H redeemable convertible preferred stock. Series H Financing In July 2019, the Company entered into an agreement with a new investor to issue shares of Series H redeemable convertible preferred stock at a per share price of $0.04712. The Company accounted for the difference between the effective conversion price of $0.04712 and the fair value of the underlying common stock at the commitment date as a beneficial conversion feature, which was immediately accreted as a deemed dividend. As a result, the Company recognized a beneficial conversion feature in the amount of $6.7 million in the third quarter of 2019, that was recorded as additional paid-in capital (in the absence of retained earnings) in the accompanying statement of redeemable convertible preferred stock and stockholders’ equity. Additionally, the Company concluded that the conversion of shares of Series G into shares of Series H redeemable convertible preferred stock in connection with the issuance of Series H redeemable convertible preferred stock represented an extinguishment of the Series G shares. As a result, the Company recognized a deemed dividend for the extinguishment charge in the amount of $6.9 million in the third quarter of 2019, that was recorded as additional paid-in capital (in the absence of retained earnings) in the accompanying statement of redeemable convertible preferred stock and stockholders' equity. Initial Public Offering Upon completion of the Company's IPO in September 2019, an aggregate of 7,816,643 shares of common stock, excluding warrant conversion, were issued to the holders of the Company's Series A-3, Series B-3, Series C, Series D, Series E, Series F and Series H redeemable convertible preferred stockholders upon the automatic conversion of all shares of redeemable convertible preferred stock to common stock. As a result, no shares of redeemable convertible preferred stock remained outstanding at December 31, 2020 and 2019.

Stockholders' Equity

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Stockholders' Equity

Reverse Stock Split

On September 6, 2019, the Company effected a one-for-183.635 reverse stock split of its common stock (the Reverse Stock Split). The par value and the authorized shares of the common stock were not adjusted as a result of the Reverse Stock Split. All issued and outstanding common stock and the conversion ratio of the redeemable convertible preferred stock have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented in the accompanying financial statements and notes to the financial statements.

Common Stock

On September 23, 2019, the Company closed its IPO of 4,140,000 shares of its common stock at a price to the public of $14.00 per share, including the exercise in full by the underwriters of their option to purchase 540,000 additional shares of the Company's common stock. Including the exercise of the option to purchase additional shares, the aggregate net proceeds to the Company from the offering was approximately $50.4 million, net of underwriting discounts, commissions and other offering expenses, for aggregate expenses of approximately $7.5 million. In addition, an aggregate of 7,816,643 shares of common stock, excluding warrant conversions, were issued to the holders of the Company's Series A-3, Series B-3, Series C, Series D, Series E, Series F and Series H redeemable convertible preferred stockholders upon the automatic conversion of all shares of redeemable convertible preferred stock to common stock.

Outstanding Warrants

The following equity classified warrants to purchase common stock were outstanding as of December 31, 2020:

Exercise Price

Issuance date

Expiration date

Common stock warrants

252,798

1.84

January 19, 2016

January 19, 2026

Common stock warrants

69,176

1.84

March 31, 2016

March 31, 2026

Common stock warrants

131

1.84

April 1, 2016

April 1, 2026

Common stock warrants

83,778

14.32

September 7, 2017

September 7, 2024

Common stock warrants

20,944

14.32

December 7, 2018

December 7, 2025

426,827

During the year ended December 31, 2020, warrants to purchase common stock were exercised resulting in the issuance of 32,120 shares of the Company's common stock and cash proceeds of an immaterial amount.

Stock Option Plan

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Stock Option Plan

In September 2019, the Company's Board of Directors adopted, and the Company's stockholders approved, the 2019 Incentive Award Plan (the 2019 Plan). A total of (i) 2,011,832 shares of common stock plus (ii) shares subject to awards granted under the 2013 Plan on or before the effective date of the 2019 Plan became available for issuance under the 2019 Plan and was initially be reserved for issuance under the 2019 Plan. Under the 2019 Plan, the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units and other awards to individuals who are then employees, officers, non-employee directors or consultants of the Company or its subsidiaries. The options generally expire ten years after the date of grant and are exercisable to the extent vested. Vesting is established by the Board of Directors and is generally four years from the date of grant. The 2019 Plan contains an "evergreen provision" that allows annual increases in the number of shares available for issuance on the first day of each calendar year through January 1, 2029 in an amount equal to the lesser of: (i) 4% of the outstanding capital stock on each December 31st, or (ii) such lesser amount determined by the Board of Directors. As of December 31, 2020, 1,139,323 shares remained available for future awards. Under the evergreen provision, on January 1, 2021, an additional 506,092 shares became available for issuance under the 2019 Plan.

Activity under the Company's stock option plans is set forth below:


	Number of Options	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Outstanding, December 31, 2019	1,375,542	$	8.33	9.16	$	23,654
Granted	951,031	$	16.02
Exercised	(47,549)	$	0.27
Forfeited	(293,412)	$	10.46
Expired	(9,851)	$	29.02
Outstanding, December 31, 2020	1,975,761	$	11.81	8.71	$	6,750
Vested and expected to vest, December 31, 2020	1,975,761	$	11.81	8.71	$	6,750
Options exercisable, December 31, 2020	464,606	$	6.75	8.01	$	3,362

The weighted-average grant date fair value per share of employee options granted to employees during the years ended December 31, 2020 and 2019 was $7.55 and $7.79, respectively. The intrinsic value is calculated as the difference between the fair value of the Company's common stock and the exercise price of the stock options. The fair value of the Company's common stock is $13.20 and $25.40 per share at December 31, 2020 and 2019, respectively. The intrinsic value of options exercised for the years ended December 31, 2020 and 2019 was $1.0 million and an immaterial amount, respectively.

Stock-Based Compensation Expense

The fair value of employee stock options was estimated using the following assumptions to determine the fair value of stock options granted:


	Years Ended December 31,
		2020	2019
Expected volatility		47%-53%	46%-59%
Risk-free interest rate		0.4%-1.7%	1.6%-2.6%
Dividend yield		—	—
Expected term (in years)		5.50-6.08	5.75-6.08

Employee Stock Purchase Plan

In September 2019, the Board of Directors adopted the Employee Stock Purchase Plan (the ESPP). The ESPP became effective on the day the ESPP was adopted by the Company's Board of Directors. The ESPP permits participants to purchase common stock through payroll deductions of up to 20% of their eligible compensation. A total of 120,000 shares of common stock was initially reserved for issuance under the ESPP. In addition, the number of shares of common stock available for issuance under the ESPP will be annually increased on the first day of each fiscal year during the term of the ESPP, beginning with the 2020 calendar year through January 1, 2029 in an amount equal to the lesser of (i) 1% of the outstanding capital stock on December 31st, or (ii) such lesser amount determined by the Board of Directors. Under the evergreen provision, on January 1, 2021, an additional 126,523 shares became available for issuances under the ESPP. Stock-based compensation expense for the ESPP was an immaterial amount for the year ended December 31, 2020.

The following assumptions were used to calculate the stock-based compensation for each stock purchase right granted under the ESPP:


	Years Ended December 31,
		2020
Expected volatility		58%-83%
Risk-free interest rate		0.1%-1.1%
Dividend yield		—
Expected term (in years)		0.5

Total non-cash stock-based compensation expense recorded related to options granted and stock purchase rights granted under the ESPP in the statement of operations is as follows (in thousands):


	Years Ended December 31,
		2020		2019
Cost of revenue		$	33	$	9
Selling, general and administrative		2,419		445
Research and development		242		118
Total		$	2,694	$	572

As of December 31, 2020, total unrecognized compensation cost was $8.5 million, which is expected to be recognized over a remaining weighted-average vesting period of 2.8 years.

Common stock reserved for future issuance consists of the following at December 31, 2020:


Warrants to purchase common stock						426,827
Common stock option grants issued and outstanding						1,975,761
Common shares available for grant under the stock option plan						1,139,323
Common shares available for future issuance under ESPP						233,961
Total						3,775,872

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

The provision for income taxes consists of the following (in thousands):


	Years Ended December 31,
	2020		2019
Current:
Federal	$	—	$	—
State	27		5
Total current	27		5
Deferred:
Federal	(117)		10
State	11		10
Total deferred	(106)		20
(Benefit) provision for income tax	$	(79)	$	25

The effective tax rate of our provision for income taxes differs from the federal statutory rate as follows:


	Years Ended December 31,
	2020		2019
Federal statutory tax rate	(21.0)	%	(21.0)	%
State income taxes, net of federal tax benefits	(3.9)	%	(3.6)	%
Change in fair value of preferred stock liabilities	—	%	(0.5)	%
Change in valuation allowance	22.6	%	(36.1)	%
Limitation of net operating losses	—	%	59.8	%
Other	1.8	%	1.6	%
Effective tax rate	(0.5)	%	0.2	%

Significant components of the Company’s deferred tax assets at December 31, 2020 and 2019 are shown below. A valuation allowance has been established as realization of the Company’s deferred tax assets has not met the more likely-than-not threshold requirement. If the Company’s judgment changes and it is determined that the Company will be able to realize these deferred tax assets, the tax benefits relating to any reversal of the valuation allowance on deferred tax assets will be accounted for as a reduction to income tax expense (in thousands).


	December 31,
	2020		2019
Deferred tax assets:
Net operating loss carryforwards	$	17,733	$	15,287
Research and development tax credits	629		419
Accruals, reserves and other	1,448		590
Interest expense	1,306		744
Basis differences in fixed and intangible assets	117		225
Total gross deferred tax assets	21,233		17,265
Less: Valuation allowance	(20,596)		(16,797)
Deferred tax assets, net	637		468
Deferred tax liabilities:
Financing and acquisition-related liabilities	(336)		(336)
Indefinite lived assets	(459)		(396)
Deferred tax liabilities, net	(795)		(732)
Net deferred tax liabilities	$	(158)	$	(264)

Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2020 and 2019, which related primarily to increases in net operating loss carryforwards, accrued revenue and accruals and reserves were as follows (in thousands):


	December 31,
	2020		2019
Valuation allowance at the beginning of the year	$	16,797	$	21,138
Decreases recorded as benefits to income tax provision	—		(4,341)
Increases recorded to income tax provision	3,799		—
Valuation allowance at the end of the year	$	20,596	$	16,797

At December 31, 2020 and 2019, the Company had federal net operating loss carryforwards of approximately $70.6 million and $60.7 million, respectively. At December 31, 2020 and 2019, the Company had state net operating loss carryforwards of $48.9 million and $43.5 million, respectively. Approximately $43.5 million of the federal tax loss carryforwards will begin to expire in 2022, unless previously utilized. The federal net operating loss carryforwards generated in after December 31, 2017 of $27.1 million will carryforward indefinitely. The Company’s state tax loss carryforwards will expire in 2032, unless previously utilized.

At December 31, 2019, the Company's deferred tax assets are primarily comprised of federal and state tax net operating loss carryforwards. The Company completed a formal study through the year ended December 31, 2019 and determined ownership changes within the meaning of Internal Revenue Code (IRC), Section 382 had occurred in 2003, 2008, 2012, 2017 and 2019. Based on the analysis, $61.8 million of the Company's tax attribute carryforwards through December 31, 2017 cannot be utilized under IRC Section 382. The Company's ability to utilize net operating loss carryforwards generated after December 31, 2017 will not expire under the Tax Cuts and Jobs Act of 2017. The Company adjusted tax attribute carry forwards and deferred tax assets accordingly. As the deferred tax assets associated with the tax attribute carry forwards were fully offset by a valuation allowance, a corresponding reduction in the Company's valuation allowance was also recorded, resulting in no income tax impact.

The Company is subject to taxation in the U.S. and in various state jurisdictions. The Company’s tax years for 2002 and forward are subject to examination by the U.S. and state tax authorities due to the carryforward of unutilized net operating losses and research and development credits.

The Company recognizes interest and/or penalties related to income tax matters in its provision for income taxes. The Company does not have any accruals for, and did not recognize any, interest or penalties in these financial statements in any period presented.

Uncertain Tax Positions

At December 31, 2020 and 2019, the Company had no unrecognized tax benefits.

The Company does not believe that the balance of unrecognized tax benefits will materially change within the next twelve months.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Related Parties	12 Months Ended
Related Parties	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Parties	Related PartiesThe closings of the Series G financing and the Series H financing described in Note 7 were issued to existing holders of the Company's redeemable convertible preferred stock, including certain members of our Board of Directors.

401(k) Plan	12 Months Ended
401(k) Plan	Dec. 31, 2020
Retirement Benefits [Abstract]
401(k) Plan	Note 12. 401(k) Plan The Company sponsors an employee savings plan that qualifies as a deferred salary arrangement under Section 401(k) of the Code. Participating employees may defer up to the Internal Revenue Service annual contribution limit. Additionally, the Company may elect to make contributions into the savings plan at its sole discretion. For the years ended December 31, 2020 and 2019, the Company made contributions to the Plan at 3% of qualified employee compensation, which totaled approximately $0.5 million and $0.4 million, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

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+ Details

Covid-19	12 Months Ended
Covid-19	Dec. 31, 2020
Reorganizations [Abstract]
Covid-19	COVID-19 During 2020, due to the worldwide COVID-19 pandemic, the Company experienced a reduction in patient test volumes, delays in patient enrollment in ongoing and planned clinical studies, and delays in the procurement of its testing supplies. In response to the pandemic, the Company has curtailed non-essential employee travel, equipped employees with the ability to work remotely with the exception of clinical laboratory employees, and reduced marketing spend and employee headcount. The reduction in headcount resulted in a restructuring charge for termination benefits of $0.3 million which has been paid as of December 31, 2020. The full extent to which the COVID-19 pandemic will directly or indirectly continue to impact the Company's business, results of operations and financial condition, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19 and the actions taken to contain it or treat COVID-19, as well as the economic impact on local, regional and international markets. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) was enacted in response to the COVID-19 pandemic. The CARES Act, among other things, permits NOL carryovers and carrybacks to offset 100% of taxable income for taxable years beginning before 2021. Under the Tax Cuts and Jobs Act (TCJA), NOLs generated post TCJA were allowed to be carried forward indefinitely but were only allowed to offset 80% of taxable income. As a result of the CARES Act and the change to permit NOLs generated in taxable years 2018, 2019 and 2020 to offset 100% of taxable income, the Company released valuation allowance against its deferred tax assets in the amount of $0.1 million for the year ended December 31, 2020. On December 27, 2020, the Consolidated Appropriations Act, 2021 was signed into law. It provides additional COVID-19 focused relief and extends certain provisions of the CARES Act. At this time, the Company does not believe that the Consolidated Appropriations Act, 2021 has a material impact on its financial statements. In April 2020, the Company received $0.7 million of funding under the CARES Act Provider Relief Fund, subject to the Company's agreement to comply with the Department of Health & Human Services' (HHS) standard terms and conditions. The CARES Act Provider Relief Fund is a federal fund allocated for general distributions to Medicare facilities and providers impacted by the COVID-19 pandemic and is intended to support COVID-related expenses or lost revenue attributable to COVID-19. The funding received is considered a government grant which is recognized when there is reasonable assurance that the grant will be received and that conditions attached to the grant have been met. For the year ended December 31, 2020, the Company recognized $0.7 million due to lost revenue attributable to COVID-19, which is reflected in other income, net, on its statements of operations.On April 16, 2020, the Company entered into a promissory note with BOKF, NA dba Bank of Oklahoma, the lender, evidencing an unsecured loan pursuant to the U.S. Small Business Administration (SBA) Paycheck Protection Program (PPP) of the CARES Act of approximately $2.9 million (the PPP Loan). The Company applied for and received the PPP Loan pursuant to the then published PPP qualification and certification requirements. On April 23, 2020, the SBA, in consultation with the Department of Treasury, issued new guidance that created uncertainty regarding the qualification requirements for the PPP Loan (the New Guidance). In light of the New Guidance, on May 11, 2020, the Company paid off in full the principal and interest on the PPP Loan, resulting in the termination of the promissory note.

Summary of Significant Accounting Policies - (Policies)	12 Months Ended
Summary of Significant Accounting Policies - (Policies)	Dec. 31, 2020
Accounting Policies [Abstract]
Concentration of Credit Risk and Other Risk and Uncertainties	Concentration of Credit Risk and Other Risk and Uncertainties Financial instruments that potentially subject the Company to credit risk consist principally of cash, cash equivalents, and accounts receivable. Substantially all the Company's cash and cash equivalents are held at one financial institution that management believes is of high credit quality. Such deposits may, at times, exceed federally insured limits.
Fair Value Measurements	Fair Value Measurements The carrying value of the Company's cash and cash equivalents approximate fair value due to the short-term nature of these items. Based on the borrowing rates currently available to the Company for debt with similar terms and consideration of default and credit risk, the carrying value of the Company's long-term borrowings approximates its fair value, which is considered a Level 2 input. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: Level 1 - Unadjusted quoted prices in active markets for identical assets or liabilities; Level 2 - Inputs other than quoted prices included within Level I that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level 3 - Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Prior to the IPO, the Company's redeemable convertible preferred stock warrant liabilities were measured at fair value on a recurring basis and were classified as Level 3 liabilities. The Company recorded subsequent adjustments to reflect the increase or decrease in estimated fair value at each reporting date in current period earnings.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The Company considers all highly-liquid investments purchased with a remaining maturity date upon acquisition of three months or less to be cash equivalents and are stated at cost, which approximates fair value.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, net of depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, generally between three and five years. Leasehold improvements are amortized on a straight-line basis over the lesser of the estimated useful life or the remaining term of the related lease. Maintenance and repairs are charged to expense as incurred, and improvements and betterments are capitalized. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the balance sheet and any resulting gain or loss is reflected in other income or expense in the statements of operations in the period realized.
Long-lived Assets	Long-lived Assets The Company’s long-lived assets are comprised principally of its property and equipment, finite lived intangible assets, and goodwill. If the Company identifies a change in the circumstances related to its long-lived assets, such as property and equipment and intangible assets (other than goodwill), that indicates the carrying value of any such asset may not be recoverable, the Company will perform an impairment analysis. A long-lived asset (other than goodwill) is deemed to be impaired when the undiscounted cash flows expected to be generated by the asset (or asset group) are less than the asset’s carrying amount. Any required impairment loss would be measured as the amount by which the asset’s carrying value exceeds its fair value, and would be recorded as a reduction in the carrying value of the related asset and a charge to operating expense. Goodwill is reviewed for impairment annually (during the fourth quarter) or more frequently if indicators of impairment exist. As the Company operates in a single operating segment and reporting unit, the Company first assesses qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit is less than its carrying amount as a basis for determining whether it is necessary to perform a quantitative assessment. If, after assessing qualitative factors, the Company determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then performing a quantitative assessment is unnecessary. If deemed necessary, a quantitative assessment compares the fair value of the reporting unit with its carrying amount, including goodwill. If the fair value of the reporting unit exceeds its carrying amount, goodwill is not considered impaired; otherwise, an impairment loss is recorded. There was no indication of impairment of goodwill for any periods presented.
Clinical Studies	Clinical StudiesFrom time to time, the Company engages in efforts to scientifically measure and document the application and efficacy of its various testing products. These arrangements typically require the Company to pay a fee to a third-party scientific investigator (usually a physician or research institution) for each subject enrolled in a clinical study, and the Company accrues expenses associated with these efforts as subjects are enrolled in each study. Expenses associated with clinical study activities are recorded in research and development expenses in the accompanying statement of operations.
Revenue Recognition	Revenue Recognition Substantially all of the Company's revenue has been derived from sales of its testing products and is primarily comprised of a high volume of relatively low-dollar transactions. The Company primarily markets its testing products to rheumatologists and their physician assistants in the United States. The healthcare professionals who order the Company's testing products and to whom test results are reported are generally not responsible for payment for these products. The parties that pay for these services (the Payors) consist of healthcare insurers, government payors (primarily Medicare and Medicaid), client payors (i.e., hospitals, other laboratories, etc.), and patient self-pay. The Company's service is a single performance obligation that is completed upon the delivery of test results to the prescribing physician which triggers revenue recognition. Payors are billed at the Company's list price. Net revenues recognized consist of amounts billed net of allowances for differences between amounts billed and the estimated consideration the Company expects to receive from such payors. The process for estimating revenues and the ultimate collection of accounts receivable involves significant judgment and estimation. The Company follows a standard process, which considers historical denial and collection experience, insurance reimbursement policies and other factors, to estimate allowances and implicit price concessions, recording adjustments in the current period as changes in estimates occur. Further adjustments to the allowances, based on actual receipts, is recorded upon settlement. The transaction price is estimated using an expected value method on a portfolio basis. The Company's portfolios are grouped per payor (i.e. each individual third-party insurance, Medicare, client payors, patient self-pay, etc.) and per test basis. Collection of the Company's net revenues from payors is normally a function of providing complete and correct billing information to the healthcare insurers and generally occurs within 30 to 90 days of billing. Contracts do not contain significant financing components based on the typical period of time between performance of services and collection of consideration.
Research and Development	Research and Development Costs associated with research and development activities are expensed as incurred and include, but are not limited to, personnel-related expenses, including stock-based compensation expense, materials, laboratory supplies, consulting costs, costs associated with setting up and conducting clinical studies and allocated overhead including rent and utilities.
Advertising and Marketing Costs	Advertising and Marketing Costs Costs associated with advertising and marketing activities are expensed as incurred. Total advertising and marketing costs were approximately $1.3 million and $1.6 million for the years ended December 31, 2020 and 2019, respectively, and are included in selling, general and administrative expenses in the accompanying statements of operations.
Stock-Based Compensation	Stock-Based Compensation The Company recognizes compensation expense for all stock-based awards to employees and directors based on the grant-date estimated fair values over the requisite service period of the awards (usually the vesting period) on a straight-line basis. The fair value of stock options and purchases under the employee stock purchase plan (ESPP) rights is determined using the Black-Scholes-Merton (BSM) option pricing model, which requires management to make certain assumptions regarding a number of complex and subjective variables. Equity award forfeitures are recorded as they occur. The BSM option pricing model incorporates various estimates, including the fair value of the Company's common stock, expected volatility, expected term and risk-free interest rates. The weighted-average expected term of options was calculated using the simplified method. This decision was based on the lack of relevant historical data due to the Company's limited historical experience. In addition, due to the Company's limited historical data, the estimated volatility incorporates the historical volatility over the expected term of the award of comparable companies whose share prices are publicly available. The risk-free interest rate for periods within the contractual term of the option is based on the U.S. Treasury yield in effect at the time of grant. The dividend yield was zero, as the Company has never declared or paid dividends and has no plans to do so in the foreseeable future. Upon the effective date of the IPO, the Company began using the closing price of its common stock as the fair value of its common stock on the corresponding date. Prior to the completion of the IPO in September 2019, due to the absence of a public market for the Company's common stock, it was necessary to estimate the fair value of the common stock underlying the Company's stock-based awards when performing fair value calculations using the BSM option pricing model. The fair value of the common stock underlying the Company's stock-based awards was assessed on each grant date by the Company's board of directors (Board of Directors).
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as a change in equity of a business enterprise during a period, resulting from transactions from nonowner sources. There have been no items qualifying as other comprehensive loss and, therefore, for all periods presented, the Company's comprehensive loss was the same as its reported net loss.
Income Taxes	Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. The Company recognizes net deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would adjust the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company records uncertain tax positions on the basis of a two-step process whereby (i) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (ii) for those tax positions that meet the more-likely-than-not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50% likely to be realized upon ultimate settlement with the related tax authority. The Company recognizes interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability.
Net Loss Per Share	Net Loss Per Share Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. Potentially dilutive common stock equivalents are comprised of redeemable convertible preferred stock, warrants for the purchase of redeemable convertible preferred and common stock, options outstanding under the Company's stock option plans and shares of the Company's common stock pursuant to Employee Stock Purchase Plan. For the years ended December 31, 2020 and 2019, there is no difference in the number of shares used to calculate basic and diluted shares outstanding as the inclusion of the potentially dilutive securities would be antidilutive.
Segment Reporting	Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations as, and manages its business in, one operating segment.
Recent Accounting Pronouncements Not Yet Adopted, Recently Adopted Accounting Standards	Recent Accounting Pronouncements Not Yet Adopted From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (FASB), or other standard setting bodies and adopted by the Company as of the specified effective date. Under the Jumpstart Our Business Startups Act of 2012 (JOBS Act), the Company meets the definition of an emerging growth company. The Company has elected to use the extended transition period for complying with new or revised accounting standards pursuant to Section 107(b) of the JOBS Act. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company's financial position or results of operations upon adoption. In February 2016, the FASB issued Accounting Standards Update (ASU) 2016-02, Leases (Topic 842). The new topic supersedes Topic 840, Leases, and increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and requires disclosures of key information about leasing arrangements. In July 2018, the FASB issued ASU 2018-10, Codification Improvements to Topic 842, which provides narrow amendments to clarify how to apply certain aspects of the new lease standard, and ASU 2018-11, Leases: Targeted Improvements, which was issued to provide relief to companies from restating comparative periods. Pursuant to this ASU, in the period of adoption the Company will not restate comparative periods presented in its financial statements. The effective date of this guidance for public companies is for reporting periods beginning after December 15, 2018. In June 2020, the FASB issued ASU 2020-05, which delays the adoption of ASU 2016-02 for non-public entities to fiscal years beginning after December 15, 2021, and interim periods beginning after December 15, 2022. As an emerging growth company as defined in the JOBS Act, the Company has elected to delay adoption of this ASU until January 1, 2022. Topic 842 mandates a modified retrospective transition method. The Company intends to adopt the new lease standard using a cumulative effect to accumulated deficit and will elect the package of practical expedients, which among other things will allow the Company to carry forward its historical lease classification. The Company is currently evaluating the impact of Topic 842 on its financial statements. In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes. The new guidance removes certain exceptions to the general principles of ASC 740 in order to simplify the complexities of its application. These changes include eliminations to the exceptions for intraperiod tax allocation, recognizing deferred tax liabilities related to outside basis differences, and year-to-date losses in interim periods, among others. The effective date of this guidance for public companies is for fiscal years, and interim period within those fiscal years, beginning after December 15, 2020. The Company does not anticipate the adoption will have a material impact on its financial statements. Recently Adopted Accounting Standards In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement: Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement, which adds and modifies certain disclosure requirements for fair value measurements. Under the new guidance, entities will no longer be required to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, or valuation processes for Level 3 fair value measurements. However, public companies will be required to disclose the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and related changes in unrealized gains and losses included in other comprehensive income. The narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. This update is effective for annual periods beginning after December 15, 2019, and interim periods within those periods, and early adoption is permitted. The Company adopted this guidance on January 1, 2020, and the adoption did not have a material impact on its financial statements.

Summary of Significant Accounting Policies - (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Schedule of Concentration of Risk, by Risk Factor and Significant Payer

For each significant payor and customers, revenue as a percentage of total revenue and accounts receivable as a percentage of total accounts receivable are as follows:


		Revenue
	Years Ended December 31,
			2020		2019
Medicare			20	%	25	%
Janssen (SIMPONI®)			12	%	*
Blue Shield			11	%	12	%
Medicare Advantage			11	%	11	%
United Healthcare			*		11	%



*						Less than 10%.


	Accounts Receivable
	December 31,
	2020		2019
Janssen (SIMPONI®)	35	%	19	%
Blue Shield	11	%	15	%
United Healthcare	*		22	%



*						Less than 10%.

Disaggregation of Revenue

The following table includes the Company's revenues as disaggregated by payor and customer category (in thousands):


	Years Ended December 31,
		2020		2019
Revenue:
Healthcare insurers		$	22,456	$	23,984
Government		8,446		9,896
Client(1)		5,109		4,392
Other(2)		836		639
Janssen (SIMPONI®)		5,128		1,476
Total revenue		$	41,975	$	40,387

(1)Includes hospitals, other laboratories, etc.

(2)Includes patient self-pay that is immaterial.

Schedule of Restricted Cash and Cash Equivalents

Cash, cash equivalents and restricted cash presented in the accompanying statements of cash flows consist of the following (in thousands):


		December 31,
	2020	2019
Cash and cash equivalents		$	57,448	$	72,084
Restricted cash		100		100
		$	57,548	$	72,184

Schedule of Cash and Cash Equivalents

Cash, cash equivalents and restricted cash presented in the accompanying statements of cash flows consist of the following (in thousands):


		December 31,
	2020	2019
Cash and cash equivalents		$	57,448	$	72,084
Restricted cash		100		100
		$	57,548	$	72,184

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common stock equivalent shares):


	Years Ended December 31,
		2020	2019


Warrants to purchase common stock		426,827	461,273
Common stock options		1,975,761	1,375,542
Employee stock purchase plan		11,640	—
Total		2,414,228	1,836,815

Other Financial Information - (Tables)

12 Months Ended

Dec. 31, 2020

Other Financial Information [Abstract]

Prepaid expenses table

Prepaid expenses and other current assets consist of the following (in thousands):


	December 31,
	2020		2019
Diagnostic testing supplies	$	1,203	$	1,427
Prepaid product royalties	68		123
Prepaid maintenance and insurance contracts	2,229		1,768
Other prepaid and other current assets	659		133
Prepaid and other current assets	$	4,159	$	3,451

Property and equipment

Property and equipment consist of the following (in thousands):


	December 31,
	2020		2019
Furniture and fixtures	$	64	$	25
Laboratory equipment	2,679		2,228
Computer equipment and software	927		851
Leasehold improvements	1,072		424
Construction in progress	301		247
Total property and equipment	5,043		3,775
Less: accumulated depreciation and amortization	(2,941)		(2,395)
Property and equipment, net	$	2,102	$	1,380

Accrued and other current liabilities

Accrued and other current liabilities consist of the following (in thousands):


	December 31,
	2020		2019
Accrued payroll and related expenses	$	3,589	$	2,362

Accrued interest	147		145
Accrued purchases of goods and services	311		319
Accrued royalties	221		727
Accrued clinical study activity	228		40
Capital lease obligations, current portion	308		238
Other accrued liabilities	953		588
Accrued and other current liabilities	$	5,757	$	4,419

Borrowings - (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Schedule of Future Minimum Aggregate Payments for Outstanding Borrowings

As of December 31, 2020, future minimum aggregate payments, including interest, for outstanding borrowings under the Loan Amendment are as follows (in thousands):


	Years Ending December 31,


2021	$	1,755
2022	2,996
2023	15,619
2024	14,280
Total	34,650
Less:
Unamortized debt discount and issuance costs	(296)
Interest	(7,695)
Total borrowings, net of discounts and debt issuance costs	$	26,659

Commitment and Contingencies (Tables)

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Future minimum payments

Minimum annual lease payments under non-cancelable lease arrangements at December 31, 2020 are as follows (in thousands):


Years Ending December 31,	Capital Leases		Operating Leases
2021	$	344	$	590
2022	318		613
2023	231		626
2024	58		640
2025	—		654
Thereafter	—		55
Total minimum lease payments	951		$	3,178
Less: amount representing interest	(67)
Present value of future minimum lease payments	884
Less: current portion	(308)
Long-term capital lease obligations	$	576

Schedule of Future Minimum Rental Payments for Operating Leases

Minimum annual lease payments under non-cancelable lease arrangements at December 31, 2020 are as follows (in thousands):


Years Ending December 31,	Capital Leases		Operating Leases
2021	$	344	$	590
2022	318		613
2023	231		626
2024	58		640
2025	—		654
Thereafter	—		55
Total minimum lease payments	951		$	3,178
Less: amount representing interest	(67)
Present value of future minimum lease payments	884
Less: current portion	(308)
Long-term capital lease obligations	$	576

Fair Value Measures and Disclosures (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Financial Instrument Measured on a Recurring Basis

The following table sets forth the Company's financial instruments that were measured at fair value on a recurring basis within the fair value hierarchy (in thousands):


	December 31, 2020
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds	$	34,507	$	34,507	$	—	$	—


	December 31, 2019
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds	$	70,760	$	70,760	$	—	$	—

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Schedule of Outstanding Warrants

The following equity classified warrants to purchase common stock were outstanding as of December 31, 2020:

Exercise Price

Issuance date

Expiration date

Common stock warrants

252,798

1.84

January 19, 2016

January 19, 2026

Common stock warrants

69,176

1.84

March 31, 2016

March 31, 2026

Common stock warrants

131

1.84

April 1, 2016

April 1, 2026

Common stock warrants

83,778

14.32

September 7, 2017

September 7, 2024

Common stock warrants

20,944

14.32

December 7, 2018

December 7, 2025

426,827

Stock Option Plan (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Stock Option Activity

Activity under the Company's stock option plans is set forth below:


	Number of Options	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Outstanding, December 31, 2019	1,375,542	$	8.33	9.16	$	23,654
Granted	951,031	$	16.02
Exercised	(47,549)	$	0.27
Forfeited	(293,412)	$	10.46
Expired	(9,851)	$	29.02
Outstanding, December 31, 2020	1,975,761	$	11.81	8.71	$	6,750
Vested and expected to vest, December 31, 2020	1,975,761	$	11.81	8.71	$	6,750
Options exercisable, December 31, 2020	464,606	$	6.75	8.01	$	3,362

Schedule of Fair Value Assumptions, Stock Options

The fair value of employee stock options was estimated using the following assumptions to determine the fair value of stock options granted:


	Years Ended December 31,
		2020	2019
Expected volatility		47%-53%	46%-59%
Risk-free interest rate		0.4%-1.7%	1.6%-2.6%
Dividend yield		—	—
Expected term (in years)		5.50-6.08	5.75-6.08

The following assumptions were used to calculate the stock-based compensation for each stock purchase right granted under the ESPP:


	Years Ended December 31,
		2020
Expected volatility		58%-83%
Risk-free interest rate		0.1%-1.1%
Dividend yield		—
Expected term (in years)		0.5

Schedule of Non-cash Stock-based Compensation Expense

Total non-cash stock-based compensation expense recorded related to options granted and stock purchase rights granted under the ESPP in the statement of operations is as follows (in thousands):


	Years Ended December 31,
		2020		2019
Cost of revenue		$	33	$	9
Selling, general and administrative		2,419		445
Research and development		242		118
Total		$	2,694	$	572

Schedule of Common Stock Reserved For Future Issuance

Common stock reserved for future issuance consists of the following at December 31, 2020:


Warrants to purchase common stock						426,827
Common stock option grants issued and outstanding						1,975,761
Common shares available for grant under the stock option plan						1,139,323
Common shares available for future issuance under ESPP						233,961
Total						3,775,872

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit)

The provision for income taxes consists of the following (in thousands):


	Years Ended December 31,
	2020		2019
Current:
Federal	$	—	$	—
State	27		5
Total current	27		5
Deferred:
Federal	(117)		10
State	11		10
Total deferred	(106)		20
(Benefit) provision for income tax	$	(79)	$	25

Schedule of Effective Income Tax Rate Reconciliation

The effective tax rate of our provision for income taxes differs from the federal statutory rate as follows:


	Years Ended December 31,
	2020		2019
Federal statutory tax rate	(21.0)	%	(21.0)	%
State income taxes, net of federal tax benefits	(3.9)	%	(3.6)	%
Change in fair value of preferred stock liabilities	—	%	(0.5)	%
Change in valuation allowance	22.6	%	(36.1)	%
Limitation of net operating losses	—	%	59.8	%
Other	1.8	%	1.6	%
Effective tax rate	(0.5)	%	0.2	%

Schedule of Deferred Tax Assets and Liabilities

If the Company’s judgment changes and it is determined that the Company will be able to realize these deferred tax assets, the tax benefits relating to any reversal of the valuation allowance on deferred tax assets will be accounted for as a reduction to income tax expense (in thousands).


	December 31,
	2020		2019
Deferred tax assets:
Net operating loss carryforwards	$	17,733	$	15,287
Research and development tax credits	629		419
Accruals, reserves and other	1,448		590
Interest expense	1,306		744
Basis differences in fixed and intangible assets	117		225
Total gross deferred tax assets	21,233		17,265
Less: Valuation allowance	(20,596)		(16,797)
Deferred tax assets, net	637		468
Deferred tax liabilities:
Financing and acquisition-related liabilities	(336)		(336)
Indefinite lived assets	(459)		(396)
Deferred tax liabilities, net	(795)		(732)
Net deferred tax liabilities	$	(158)	$	(264)

Summary of Valuation Allowance


	December 31,
	2020		2019
Valuation allowance at the beginning of the year	$	16,797	$	21,138
Decreases recorded as benefits to income tax provision	—		(4,341)
Increases recorded to income tax provision	3,799		—
Valuation allowance at the end of the year	$	20,596	$	16,797

Organization - (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 57,448	$ 72,084
Accumulated deficit	$ 181,289	$ 164,602

Summary of Significant Accounting Policies - Revenue by Major Payers (Details) - Customer Concentration Risk	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Medicare \| Revenue Benchmark
Disaggregation of Revenue [Line Items]
Percent of total revenue		20.00%	25.00%
Janssen (SIMPONI) \| Revenue Benchmark
Disaggregation of Revenue [Line Items]
Percent of total revenue		12.00%
Janssen (SIMPONI) \| Accounts Receivable
Disaggregation of Revenue [Line Items]
Percent of total revenue		35.00%	19.00%
Blue Shield \| Revenue Benchmark
Disaggregation of Revenue [Line Items]
Percent of total revenue		11.00%	12.00%
Blue Shield \| Accounts Receivable
Disaggregation of Revenue [Line Items]
Percent of total revenue	15.00%	11.00%
Medicare Advantage \| Revenue Benchmark
Disaggregation of Revenue [Line Items]
Percent of total revenue		11.00%	11.00%
United Healthcare \| Revenue Benchmark
Disaggregation of Revenue [Line Items]
Percent of total revenue			11.00%
United Healthcare \| Accounts Receivable
Disaggregation of Revenue [Line Items]
Percent of total revenue	22.00%

Summary of Significant Accounting Policies - Narrative (Details) $ in Thousands		3 Months Ended	12 Months Ended
	Sep. 23, 2019 shares	Dec. 31, 2020 USD ($) unit	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($) shares	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2016 USD ($)
New Accounting Pronouncement, Early Adoption [Line Items]
Restricted cash		$ 100	$ 100	$ 100
Contract with customer, timing of performance obligation and payment			Collection of the Company's net revenues from payors is normally a function of providing complete and correct billing information to the healthcare insurers and generally occurs within 30 to 90 days of billing
Joint venture, quarterly promotion fee		$ 300	$ 300
Joint venture quarterly promotion fee cap		5.00%	5.00%				5.00%
Joint venture, number of units prescribed quarterly \| unit		28,750
Revenue			$ 41,975	40,387
Advertising Expense			$ 1,300	$ 1,600
Dividend yield			0.00%
Number of operating segments \| segment			1
Common Stock
New Accounting Pronouncement, Early Adoption [Line Items]
Stock issued upon conversion of redeemable convertible preferred shares (in shares) \| shares				7,816,643
Common Stock \| IPO
New Accounting Pronouncement, Early Adoption [Line Items]
Stock issued upon conversion of redeemable convertible preferred shares (in shares) \| shares	7,816,643
Forecast
New Accounting Pronouncement, Early Adoption [Line Items]
Joint venture quarterly promotion fee cap					10.00%	10.00%
Minimum
New Accounting Pronouncement, Early Adoption [Line Items]
Property, plant and equipment, useful life			3 years
Joint venture, quarterly promotion fee per prescription								$ 750
Joint venture, quarterly promotion fee		$ 300	$ 300				$ 300
Minimum \| Forecast
New Accounting Pronouncement, Early Adoption [Line Items]
Joint venture, quarterly promotion fee per prescription					$ 500	$ 500
Joint venture, quarterly promotion fee					300	300
Maximum
New Accounting Pronouncement, Early Adoption [Line Items]
Property, plant and equipment, useful life			5 years
Joint venture, quarterly promotion fee per prescription								$ 1,250
Maximum \| Forecast
New Accounting Pronouncement, Early Adoption [Line Items]
Joint venture, quarterly promotion fee per prescription					$ 1,000	$ 1,000
Shipping and Handling
New Accounting Pronouncement, Early Adoption [Line Items]
Cost of revenue			$ 1,400	$ 1,400
Revenue Benchmark \| Supplier Concentration Risk
New Accounting Pronouncement, Early Adoption [Line Items]
Percent of total revenue			97.00%	97.00%
Revenue Benchmark \| AVISE CTD Test \| Product Concentration Risk
New Accounting Pronouncement, Early Adoption [Line Items]
Percent of total revenue			70.00%	82.00%
Janssen (SIMPONI)
New Accounting Pronouncement, Early Adoption [Line Items]
Revenue			$ 5,100	$ 1,500
Other assets
New Accounting Pronouncement, Early Adoption [Line Items]
Restricted cash									$ 100

Summary of Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 41,975	$ 40,387
Healthcare insurers
Disaggregation of Revenue [Line Items]
Revenue	22,456	23,984
Government
Disaggregation of Revenue [Line Items]
Revenue	8,446	9,896
Client
Disaggregation of Revenue [Line Items]
Revenue	5,109	4,392
Other
Disaggregation of Revenue [Line Items]
Revenue	836	639
Janssen (SIMPONI)
Disaggregation of Revenue [Line Items]
Revenue	$ 5,128	$ 1,476

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Summary of Significant Accounting Policies - Cash, cash equivalents and restricted cash (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Cash and cash equivalents	$ 57,448	$ 72,084
Restricted cash	100	100
Total cash, cash equivalents and restricted cash	$ 57,548	$ 72,184	$ 13,264

Summary of Significant Accounting Policies - Securities (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Anti-dilutive securities excluded from computation (in shares)	2,414,228	1,836,815
Warrants to purchase common stock
Class of Stock [Line Items]
Anti-dilutive securities excluded from computation (in shares)	426,827	461,273
Common stock options
Class of Stock [Line Items]
Anti-dilutive securities excluded from computation (in shares)	1,975,761	1,375,542
Employee stock purchase plan
Class of Stock [Line Items]
Anti-dilutive securities excluded from computation (in shares)	11,640	0

Other Financial Information - Prepaid expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other Financial Information [Abstract]
Diagnostic testing supplies	$ 1,203	$ 1,427
Prepaid product royalties	68	123
Prepaid maintenance and insurance contracts	2,229	1,768
Other prepaid and other current assets	659	133
Prepaid and other current assets	$ 4,159	$ 3,451

Other Financial Information - Property and equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 5,043	$ 3,775
Less: accumulated depreciation and amortization	(2,941)	(2,395)
Property and equipment, net	2,102	1,380
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	64	25
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	2,679	2,228
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment	927	851
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	1,072	424
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 301	$ 247

Other Financial Information - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 500	$ 600
Property and equipment, gross	5,043	3,775
Assets under capital lease
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,200	$ 800

Other Financial Information - Accrued liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other Financial Information [Abstract]
Accrued payroll and related expenses	$ 3,589	$ 2,362
Accrued interest	147	145
Accrued purchases of goods and services	311	319
Accrued royalties	221	727
Accrued clinical study activity	228	40
Capital lease obligations, current portion	308	238
Other accrued liabilities	953	588
Accrued and other current liabilities	$ 5,757	$ 4,419

Borrowings - Narrative (Details) $ in Millions		1 Months Ended		12 Months Ended
Borrowings - Narrative (Details) $ in Millions	Dec. 07, 2018 USD ($)	Nov. 30, 2019 payment	Sep. 30, 2017 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Loan payable \| Capital Royalty Partners II LP
Debt Instrument [Line Items]
Loan repayment			$ 17.8
2017 Term loan \| Loan payable \| Innovatus Life Sciences Lending Fund
Debt Instrument [Line Items]
Term loan borrowings	$ 5.0		$ 20.0
Term loan, interest rate		8.50%
Term loan, paid in-kind, interest rate		2.00%
Term loan, effective interest rate				10.00%
Number of payments \| payment		24
Term loan, fee incurred upon payment of final installment				$ 1.0
Term loan, prepayment premium percentage				3.00%
Term loan, annual reduction in prepayment penalty percentage				1.00%
Term loan, covenant, revenue performance period				12 months
Term loan, covenant, number of days to cure covenant if performance measure is not met				60 days
Term loan covenant, minimum unrestricted cash balance				$ 2.0
Term loan covenant, increase to interest rate				4.00%
2017 Term loan \| Paid in-kind note \| Innovatus Life Sciences Lending Fund
Debt Instrument [Line Items]
Term loan, paid in-kind loans issued				$ 0.5	$ 0.5

Borrowings - Future minimum payments (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Debt Disclosure [Abstract]
2021	$ 1,755
2022	2,996
2023	15,619
2024	14,280
Total	34,650
Unamortized debt discount and issuance costs	(296)
Interest	(7,695)
Total borrowings, net of discounts and debt issuance costs	$ 26,659

Commitment and Contingencies - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Rent expense	$ 600,000	$ 500,000
Purchase obligation, due in next twelve months	4,100,000
Purchase obligation, due in second year	$ 6,000,000.0
Annual increase in purchase commitments	15.00%
Minimum \| Licensing Agreements
Loss Contingencies [Line Items]
Royalty obligation, percent of net sales	2.00%
Maximum \| Licensing Agreements
Loss Contingencies [Line Items]
Royalty obligation, percent of net sales	3.00%
Prometheus Laboratories
Loss Contingencies [Line Items]
Remaining milestone obligation	$ 2,000,000.0
Remaining milestone obligation, fair value	$ 0	$ 0
Royalty obligation, percent of net sales	2.50%
Future minimum royalty commitment	$ 1,200,000
Advance royalties payment	$ 100,000
Office and Laboratory
Loss Contingencies [Line Items]
Operating leases, renewal term	5 years
Office
Loss Contingencies [Line Items]
Operating leases, renewal term	5 years

Commitment and Contingencies - Minimum annual lease payments under non-cancelable lease arrangements (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Capital Leases
2021	$ 344
2022	318
2023	231
2024	58
2025	0
Thereafter	0
Total minimum lease payments	951
Less: amount representing interest	(67)
Present value of future minimum lease payments	884
Less: current portion	(308)	$ (238)
Long-term capital lease obligations	576
Operating Leases
2021	590
2022	613
2023	626
2024	640
2025	654
Thereafter	55
Total minimum lease payments	$ 3,178

Fair Value Measurements (Details) - Recurring - Money market funds - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets:
Money market funds	$ 34,507	$ 70,760
Level 1
Assets:
Money market funds	34,507	70,760
Level 2
Assets:
Money market funds	0	0
Level 3
Assets:
Money market funds	$ 0	$ 0

Redeemable Convertible Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		3 Months Ended	12 Months Ended
	Sep. 23, 2019	Jul. 31, 2019	Jan. 31, 2019	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Temporary Equity [Line Items]
Beneficial conversion feature, temporary equity						$ 6,741
Deemed dividend from conversion of Series G to Series H redeemable convertible preferred stock (Note 7)				$ 6,900		$ 6,860
Redeemable convertible preferred stock outstanding (in shares)					0	0	532,606,084
Common Stock
Temporary Equity [Line Items]
Stock issued upon conversion of redeemable convertible preferred shares (in shares)						7,816,643
Common Stock \| IPO
Temporary Equity [Line Items]
Stock issued upon conversion of redeemable convertible preferred shares (in shares)	7,816,643
Series G redeemable convertible preferred stock
Temporary Equity [Line Items]
Sale of temporary equity, price per share (in dollars per share)			$ 0.078			$ 0.078
Series H redeemable convertible preferred stock
Temporary Equity [Line Items]
Sale of temporary equity, price per share (in dollars per share)		$ 0.04712				$ 0.047
Beneficial conversion feature, temporary equity				$ 6,700	$ 0	$ 6,741
Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock outstanding (in shares)					0	0

Stockholders' Equity - Narrative (Details) $ / shares in Units, $ in Thousands			12 Months Ended
	Sep. 23, 2019 USD ($) $ / shares shares	Sep. 06, 2019	Dec. 31, 2019 shares
Subsidiary, Sale of Stock [Line Items]
Reverse stock split ratio, common stock		0.0054456
Common Stock
Subsidiary, Sale of Stock [Line Items]
Stock issued upon conversion of redeemable convertible preferred shares (in shares)			7,816,643
IPO \| Common Stock
Subsidiary, Sale of Stock [Line Items]
Initial public offering (in shares)	4,140,000
Shares issued in public offering, price per share (in dollars per share) \| $ / shares	$ 14.00
Proceeds from public offering, net \| $	$ 50,400
Estimated offering expenses for aggregate expenses \| $	$ 7,500
Stock issued upon conversion of redeemable convertible preferred shares (in shares)	7,816,643
Over-Allotment Option \| Common Stock
Subsidiary, Sale of Stock [Line Items]
Initial public offering (in shares)	540,000

Stockholders' Equity (Details)	Dec. 31, 2020 $ / shares shares
Class of Stock [Line Items]
Warrants issued to purchase redeemable convertible preferred stock	426,827
Number of warrants exercised common stock (in shares)	32,120
Warrant expiration January 19, 2026
Class of Stock [Line Items]
Warrants issued to purchase redeemable convertible preferred stock	252,798
Class of warrant or right, exercise price of warrants or rights (in dollars per share) \| $ / shares	$ 1.84
Warrant expiration March 31, 2026
Class of Stock [Line Items]
Warrants issued to purchase redeemable convertible preferred stock	69,176
Class of warrant or right, exercise price of warrants or rights (in dollars per share) \| $ / shares	$ 1.84
Warrant expiration April 1, 2026
Class of Stock [Line Items]
Warrants issued to purchase redeemable convertible preferred stock	131
Class of warrant or right, exercise price of warrants or rights (in dollars per share) \| $ / shares	$ 1.84
Warrant expiration September 7, 2024
Class of Stock [Line Items]
Warrants issued to purchase redeemable convertible preferred stock	83,778
Class of warrant or right, exercise price of warrants or rights (in dollars per share) \| $ / shares	$ 14.32
Warrant expiration December 7, 2025
Class of Stock [Line Items]
Warrants issued to purchase redeemable convertible preferred stock	20,944
Class of warrant or right, exercise price of warrants or rights (in dollars per share) \| $ / shares	$ 14.32

Stock Option Plan - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee options, weighted-average grant date fair value per share (in dollars per share)	$ 7.55	$ 7.79
Common stock, fair value per share (in dollars per share)	$ 13.20	$ 25.40
Intrinsic value of options exercised	$ 1.0	$ 1.0
Stock options, unrecognized compensation cost	$ 8.5
Stock options, cost not yet recognized, remaining weighted average vesting period	2 years 9 months 18 days
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, expiration period	10 years
Stock options, vesting period	4 years
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance under Stock Option Plan	120,000
Annual percentage increase in shares available for issuance under the Plan	1.00%
Maximum Employee payroll deduction percentage	20.00%
Employee stock purchase plan \| Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase (decrease) in number of shares authorized (in shares)			126,523
2019 Incentive Award Plan \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance under Stock Option Plan	2,011,832
Annual percentage increase in shares available for issuance under the Plan	4.00%
Shares that remain available for future awards	1,139,323
2019 Incentive Award Plan \| Stock options \| Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase (decrease) in number of shares authorized (in shares)			506,092

Stock Option Plan - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, December 31, 2019 (in shares)	1,375,542
Granted (in Shares)	951,031
Exercised (in Shares)	(47,549)
Forfeited (in Shares)	(293,412)
Expired (in Shares)	(9,851)
Outstanding, December 31, 2020 (in shares)	1,975,761	1,375,542
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding, December 31, 2019, Weighted Average Exercise Price (in dollars per share)	$ 8.33
Granted, Weighted Average Exercise Price (in dollars per share)	16.02
Exercised, Weighted Average Exercise Price (in dollars per share)	0.27
Forfeited, Weighted Average Exercise Price (in dollars per share)	10.46
Expired, Weighted Average Exercise Price (in dollars per share)	29.02
Outstanding, December 31, 2020, Weighted Average Exercise Price (in dollars per share)	$ 11.81	$ 8.33
Stock Options, Additional Disclosures [Abstract]
Outstanding, Weighted Average Remaining Contractual Term	8 years 8 months 15 days	9 years 1 month 28 days
Vested and expected to vest, Weighted Average Remaining Contractual Term	8 years 8 months 15 days
Options exercisable, Weighted Average Remaining Contractual Term	8 years 3 days
Outstanding, Aggregate Intrinsic Value	$ 6,750	$ 23,654
Vested and expected to vest, Aggregate Intrinsic Value	6,750
Options exercisable, Aggregate Intrinsic Value	$ 3,362
Vested and expected to vest, December 31, 2020 (in shares)	1,975,761
Vested and expected to vest, December 31, 2020, Weighted Average Exercise Price (in dollars per share)	$ 11.81
Options exercisable, December 31, 2020 (in Shares)	464,606
Options exercisable, December 31, 2020, December 31, 2020, Weighted Average Exercise Price (in dollars per share)	$ 6.75

Stock Option Plan - Fair Value Assumptions (Details)	12 Months Ended
Stock Option Plan - Fair Value Assumptions (Details)	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility rate, minimum	47.00%	46.00%
Expected volatility rate, maximum	53.00%	59.00%
Risk-free interest rate, minimum	0.40%	1.60%
Risk-free interest rate, maximum	1.70%	2.60%
Dividend yield	0.00%	0.00%
Stock options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years 6 months	5 years 9 months
Stock options \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 29 days	6 years 29 days
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility rate, minimum	58.00%
Expected volatility rate, maximum	83.00%
Risk-free interest rate, minimum	0.10%
Risk-free interest rate, maximum	1.10%
Dividend yield	0.00%
Expected term (in years)	6 months

Stock Option Plan - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,694	$ 572
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	33	9
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2,419	445
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 242	$ 118

Stock Option Plan - Common Stock Reserved For Future Issuance (Details)	Dec. 31, 2020 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	3,775,872
Warrants to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	426,827
Common stock option grants issued and outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	1,975,761
Common shares available for grant under the stock option plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	1,139,323
Common shares available for future issuance under ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	233,961

Income Taxes - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Current:
Federal	$ 0	$ 0
State	27	5
Total current	27	5
Deferred:
Federal	(117)	10
State	11	10
Total deferred	(106)	20
(Benefit) provision for income tax	$ (79)	$ 25

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Income Taxes - Reconciliation of Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Federal statutory tax rate	(21.00%)	(21.00%)
State income taxes, net of federal tax benefits	(3.90%)	(3.60%)
Change in fair value of preferred stock liabilities	0.00%	(0.50%)
Change in valuation allowance	22.60%	(36.10%)
Limitation of net operating losses	0.00%	59.80%
Other	1.80%	1.60%
Effective tax rate	(0.50%)	0.20%

Income Taxes - Reconciliation of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$ 17,733	$ 15,287
Research and development tax credits	629	419
Accruals, reserves and other	1,448	590
Interest expense	1,306	744
Basis differences in fixed and intangible assets	117	225
Total gross deferred tax assets	21,233	17,265
Less: Valuation allowance	(20,596)	(16,797)	$ (21,138)
Deferred tax assets, net	637	468
Deferred tax liabilities:
Financing and acquisition-related liabilities	(336)	(336)
Indefinite lived assets	(459)	(396)
Deferred tax liabilities, net	(795)	(732)
Net deferred tax liabilities	$ (158)	$ (264)

Income Taxes - Change In Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Changes In The Valuation Allowance For Deferred Tax Assets [Roll Forward]
Valuation allowance at the beginning of the year	$ 16,797	$ 21,138
Decreases recorded as benefits to income tax provision	0	(4,341)
Increases recorded to income tax provision	3,799	0
Valuation allowance at the end of the year	$ 20,596	$ 16,797

Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Federal net operating loss carryforwards	$ 70,600,000	$ 60,700,000
State net operating loss carryforwards	48,900,000	43,500,000
Federal tax loss carryforwards, subject to expiration	43,500,000
Federal net operating loss carryforwards, carryforward indefinitely	27,100,000
Tax attribute carryforwards cannot be utilized under IRC Section 382	61,800,000
Unrecognized tax benefits	$ 0	$ 0

401(k) Plan (Details) - USD ($) $ in Millions	12 Months Ended
401(k) Plan (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Retirement Benefits [Abstract]
Qualified employee compensation, employer matching contribution, percent of employees' gross pay	3.00%	3.00%
Qualified employee compensation contribution, amount	$ 0.5	$ 0.4

Covid-19 (Details) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
Covid-19 (Details) - USD ($) $ in Thousands	Apr. 16, 2020	Apr. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2020
Restructuring Cost and Reserve [Line Items]
Coronavirus, Aid, Relief, And Economic Securities (CARES) Act, deferred tax assets, income tax benefit					$ 100
Proceeds from Paycheck Protection Program loan	$ 2,900	$ 700	$ 2,865	$ 0
Other income, net attributable to COVID-10			700
One-time Termination Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 300