0001274737-23-000019 | 10-K | XBRL Viewer

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Cover - USD ($) $ in Millions	12 Months Ended
Cover - USD ($) $ in Millions	Dec. 31, 2022	Mar. 16, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Current Fiscal Year End Date	--12-31
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			$ 61.5
Entity Common Stock, Shares Outstanding		16,825,696
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 2023 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.
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Central Index Key	0001274737

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2022
Audit Information [Abstract]
Auditor Name	BDO USA, LLP
Auditor Location	San Diego, California
Auditor Firm ID	243

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 62,391	$ 99,442
Accounts receivable, net	6,077	9,654
Prepaid expenses and other current assets	4,143	3,638
Total current assets	72,611	112,734
Property and equipment, net	8,197	4,772
Operating lease right-of-use assets	4,885	0
Goodwill	0	5,506
Other assets	528	433
Total assets	86,221	123,445
Current liabilities:
Accounts payable	3,046	2,492
Operating lease liabilities	1,040	0
Borrowings-current portion	190	0
Accrued and other current liabilities	5,347	6,826
Total current liabilities	9,623	9,318
Borrowings-non-current portion, net of discounts and debt issuance costs	28,778	27,478
Non-current operating lease liabilities	4,493	0
Deferred tax liabilities	0	306
Other non-current liabilities	867	1,407
Total liabilities	43,761	38,509
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, 2022 and December 31, 2021	0	0
Common stock, $0.001 par value; 200,000,000 shares authorized at December 31, 2022 and December 31, 2021; 16,549,984 and 16,164,994 shares issued and outstanding at December 31, 2022 and December 31, 2021, respectively	17	16
Additional paid-in capital	297,970	293,060
Accumulated deficit	(255,527)	(208,140)
Total stockholders' equity	42,460	84,936
Total liabilities and stockholders' equity	$ 86,221	$ 123,445

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
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
Shares outstanding (in shares)	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)	16,549,984	16,164,994
Shares outstanding (in shares)	16,549,984	16,164,994

Statements of Operations - USD ($) $ in Thousands	12 Months Ended
Statements of Operations - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Revenue	$ 45,563	$ 48,299
Operating expenses:
Costs of revenue	24,214	20,588
Selling, general and administrative expenses	52,018	44,541
Research and development expenses	9,876	7,237
Goodwill Impairment	5,506	0
Total operating expenses	91,614	72,366
Loss from operations	(46,051)	(24,067)
Interest expense	(2,448)	(2,625)
Interest income	830	16
Loss before income taxes	(47,669)	(26,676)
Income tax expense	282	(175)
Net loss	$ (47,387)	$ (26,851)
Net loss per share, basic (in dollars per share)	$ (2.77)	$ (1.68)
Net loss per share, diluted (in dollars per share)	$ (2.77)	$ (1.68)
Weighted-average number of shares used to compute net loss per share, basic (in shares)	17,082,348	15,972,256
Weighted-average number of shares used to compute net loss per share, diluted (in shares)	17,082,348	15,972,256

Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2020		12,652,308
Beginning balance at Dec. 31, 2020	$ 41,839	$ 13	$ 223,115	$ (181,289)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock in public offering, net of issuance costs of $4,435 (in shares)		4,255,000
Issuance of stock in public offering, net of issuance costs of $4,435	64,709	$ 4	64,705
Retirement of common stock in exchange for common stock warrant (in shares)		(804,951)
Retirement of common stock in exchange for common stock warrant	(12,775)	$ (1)	(12,774)
Issuance of common stock warrant in exchange for retirement of common stock	12,775		12,775
Exercise of stock options (in shares)		11,950
Exercise of stock options	89		89
Issuance of stock under Employee Stock Purchase Plan (in shares)		32,968
Issuance of stock under Employee Stock Purchase Plan	390		390
Stock-based compensation	4,728		4,728
Exercise of common stock warrants (in shares)		17,719
Exercise of common stock warrants	32		32
Net loss	$ (26,851)			(26,851)
Ending balance (in shares) at Dec. 31, 2021	16,164,994	16,164,994
Ending balance at Dec. 31, 2021	$ 84,936	$ 16	293,060	(208,140)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock from vested restricted stock units and payment of employees' taxes (in shares)		64,064
Issuance of stock from vested restricted stock units and payment of employees' taxes	$ (239)		(239)
Exercise of stock options (in shares)	245,186	245,186
Exercise of stock options	$ 61	$ 1	60
Issuance of stock under Employee Stock Purchase Plan (in shares)		75,740
Issuance of stock under Employee Stock Purchase Plan	385		385
Stock-based compensation	$ 4,704		4,704
Exercise of common stock warrants (in shares)	0
Net loss	$ (47,387)			(47,387)
Ending balance (in shares) at Dec. 31, 2022	16,549,984	16,549,984
Ending balance at Dec. 31, 2022	$ 42,460	$ 17	$ 297,970	$ (255,527)

Statements of Stockholders' Equity (Parenthetical) $ in Thousands	Dec. 31, 2021 USD ($)
Statement of Financial Position [Abstract]
Stock issuance costs	$ 4,435

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net loss	$ (47,387)	$ (26,851)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,557	948
Amortization of debt discount and debt issuance costs	161	279
Non-cash interest expense	551	540
Deferred income taxes	(306)	148
Non-cash lease expense	967	0
Long-lived assets impairment	397	0
Goodwill Impairment	5,506	0
Stock-based compensation	4,704	4,728
Other	36	0
Changes in assets and liabilities:
Accounts receivable, net	3,577	(744)
Prepaid expenses and other current assets	(505)	521
Other assets	(47)	(167)
Operating lease liabilities	(854)	0
Accounts payable	901	(655)
Accrued and other current liabilities	(1,402)	984
Net cash used in operating activities	(32,144)	(20,269)
Cash flows from investing activities:
Purchases of property and equipment	(4,318)	(2,370)
Purchase of other assets	0	(50)
Net cash used in investing activities	(4,318)	(2,420)
Cash flows from financing activities:
Proceeds from exercise of stock options	61	89
Payments of taxes withheld on vested restricted stock units	(239)	0
Proceeds from common stock issued under Employee Stock Purchase Plan	385	390
Proceeds from exercise of common stock warrants	0	32
Principal payment on finance lease obligations	(667)	(525)
Principal payment on note payable obligations	(29)	0
Proceeds from the issuance of common stock in public offering, gross	0	69,144
Net cash (used in) provided by financing activities	(489)	64,683
Net change in cash, cash equivalents and restricted cash	(36,951)	41,994
Cash, cash equivalents and restricted cash, beginning of year	99,542	57,548
Cash, cash equivalents and restricted cash, end of year	62,591	99,542
Supplemental disclosure of cash flow information:
Cash paid for interest expense	1,732	1,815
Supplemental disclosure of non-cash items:
Equipment purchased under finance lease obligations	741	1,111
Equipment purchased under notes payable obligations	807	0
Costs incurred, but not paid, in connection with capital expenditures	182	685
Deferred offering costs reclassified to equity	0	28
Public Offering
Cash flows from financing activities:
Payment of issuance costs related to public offering	0	(4,407)
Other Offering
Cash flows from financing activities:
Payment of issuance costs related to public offering	$ 0	$ (40)

Organization	12 Months Ended
Organization	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Description of Business Exagen Inc. (the Company) is a commercial-stage diagnostics company dedicated to helping 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, 2022, the Company had cash and cash equivalents of $62.4 million and had an accumulated deficit of $255.5 million. Since inception, the Company has financed its operations primarily through a combination of equity financings, debt financing arrangements, and revenue from sales of the Company's products. 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, 2022

Accounting Policies [Abstract]

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 estimated incremental borrowing rate for the determination of the Company's operating lease right-of-use (ROU) assets, the recoverability of its long-lived assets and the goodwill impairment test. 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. We have not experienced any losses on our cash or cash equivalents.

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 customer,

revenue as a percentage of total revenue and accounts receivable as a percentage of total accounts receivable are as follows:


	Revenue
	Year Ended December 31,
	2022		2021
Medicare	39	%	19	%
Medicare Advantage	15	%	13	%
Blue Shield	*		12	%



*						Less than 10%.


	Accounts Receivable
	December 31,
	2022		2021
Medicare	21	%	*
Medicare Advantage	13	%	*
Blue Shield	*		19	%
United Healthcare	*		18	%



*						Less than 10%.

For the years ended December 31, 2022 and 2021, approximately 84% and 81% 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, 2022 and 2021, approximately 96% 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):


	Year Ended December 31,
	2022		2021
Revenue:
Commercial	$	18,975	$	27,499
Government	17,687		9,221
Client(1)	7,928		9,288
Other(2)	973		1,091
Janssen (SIMPONI®)	—		1,200
Total revenue	$	45,563	$	48,299

(1)Includes hospitals, other laboratories, etc.

(2)Includes patient self-pay.

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.

The Company has 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 certificate of

deposit with this financial institution as collateral for the balances borrowed on these credit cards ($0.2 million and $0.1 million at December 31, 2022 and 2021, respectively). 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,
	2022		2021
Cash and cash equivalents	$	62,391	$	99,442
Restricted cash	200		100
	$	62,591	$	99,542

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 operating expenses 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 and operating lease assets (see Note 5).

We amortize all finite lived intangible assets over their respective estimated useful lives. Operating lease assets are amortized over the term of the leases. In considering whether long-lived assets are impaired, we combine our intangible assets and other long-lived assets (excluding goodwill), into groupings, a determination which we principally make on the basis of whether the assets are specific to a particular test offered by us or technology we are developing. 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. Management’s estimates of future cash flows are impacted by projected test volume and levels of reimbursement, as well as expectations related to the future cost structure of the entity. 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.

During the year ended December 31, 2022, the Company recorded an impairment charge to fixed assets totaling $0.4 million (see Note 3). The impairment charge was classified within research and development expenses in the accompanying statements of operations.

Goodwill

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.

During the year ended December 31, 2022, the Company recorded an impairment charge to goodwill totaling $5.5 million (see Note 3).

Leases

The Company categorizes leases at their commencement as either operating or finance leases. Effective January 1, 2022 upon the adoption of Accounting Standards Codification (ASC) 842, the Company recognizes operating lease ROU assets and operating lease liabilities for each lease arrangement identified. Lease liabilities are recorded at the present value of future lease payments discounted using the Company's incremental borrowing rate for the lease established at the commencement date. ROU assets are measured at the amount of the lease liability plus any initial direct costs, less any lease incentives received before commencement. Lease expense is recognized as a single lease cost over the lease term on a straight-line basis. The Company has elected not to apply the recognition requirements to short-term leases and not to separate non-lease components from lease components for its leases.

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 based on estimated progress of services performed, including actual level of subjects enrolled and progress of the clinical studies. Payments made prior to the completion of clinical study services are capitalized as a prepaid expense. The prepaid amounts are expensed as the related goods are delivered or the services are performed, or when it is no longer expected that the goods will be delivered or the services rendered. Expenses associated with clinical study activities are recorded in research and development expenses in the accompanying statement of operations.

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 (each, a payor) consist of commercial payors (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, are recorded upon settlement. Included in revenues for the years ended December 31, 2022 and 2021 was a net revenue decrease of $2.4 million and a net revenue increase of $0.7 million, respectively, associated with changes in estimated variable consideration related to performance obligations satisfied in previous periods. The transaction price is estimated using an expected value method on a portfolio basis.

Variable consideration is included in the transaction price only to the extent it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainties with respect to the amount are resolved. The Company's portfolios are grouped per payor (i.e. each individual commercial payor, Medicare, Medicaid, client payors, patient self-pay, etc.) and per test. Consideration may be constrained and excluded from the transaction price in situations where there is no contractually agreed upon reimbursement coverage or in absence of a predictable pattern and history of collectability with a payor. Accordingly, in such situations revenues are recognized on the basis of actual cash collections. Additionally, from time to time, the Company may issue refunds to payors for overpayments or amounts billed in error. Any refunds are accounted for as reductions in revenues in the statement of operations as an element of variable consideration. The estimated expected refunds are accrued as a liability on the Company’s balance sheet.

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 (as amended from time to time, the Janssen Agreement) with Janssen Biotech, Inc. (Janssen) to co-promote SIMPONI® in the United States. In August 2021, the Company and Janssen mutually agreed to terminate the Janssen Agreement, effective August 31, 2021.

Pursuant to the Janssen Agreement, as amended, the Company was responsible for the costs associated with its sales force over the course of such co-promotion. Janssen was 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 was 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. The Company's obligations relating to sales and co-promotion services for SIMPONI® were a series of single performance obligations since Janssen simultaneously received and consumed benefits provided by the Company's sales and co-promotional services. The method for measuring progress towards satisfying the performance obligations was based on prescribed units in excess of the contractual baseline at the contractual rate earned per unit. The Company recognized no co-promotion revenue and $1.2 million in co-promotion revenue during the years ended December 31, 2022 and December 31, 2021, respectively. The related expenses for marketing SIMPONI® were included in selling, general and administrative expenses and were expensed as incurred.

Pursuant to the terms of the termination, the Company received $0.6 million in consideration (which was earned in the year ended December 31, 2021) and the Company was restricted until May 31, 2022 from promoting any other biologic or Janus kinase inhibitor used for the treatment of indications covered by the Janssen Agreement without first obtaining Janssen's written consent. The restriction no longer applies.

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 $3.0 million and $1.7 million for the years ended December 31, 2022 and 2021, 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 $2.7 million and $2.1 million, for the years ended December 31, 2022 and 2021, respectively.

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 Company's 2019 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 inputs, including the fair value of the Company's common stock, expected volatility, expected term and risk-free interest rates. Volatility is based on the Company's historical calculated volatility since being publicly traded. The weighted-average expected term of options was calculated using the simplified method. 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 is zero, as the Company has never declared or paid dividends and has no plans to do so in the foreseeable future.

The fair value of each restricted stock unit is determined on the grant date using the closing price of the Company's common stock on that date. The Company's restricted stock units generally vest in equal annual installments over four years from the date of grant or, for grants to new hires, date of hire. Vesting of restricted stock units is subject to the holder's continued service with the Company. The Company issues new shares to satisfy restricted stock units upon vesting.

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 shares and common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. The weighted-average number of shares used to compute basic and diluted shares includes shares issuable upon the exercise of pre-funded warrants at a nominal price. Potentially dilutive common stock equivalents are comprised of warrants for the purchase of common stock, options and restricted stock units outstanding under the Company's 2019 Incentive Award Plan (the 2019 Plan) and shares of the Company's common stock pursuant to the ESPP. For the years ended December 31, 2022 and 2021, 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,
	2022	2021


Warrants to purchase common stock	409,108	409,108
Common stock options	1,421,235	2,014,330
Restricted stock units	1,036,208	415,325
Employee stock purchase plan	58,711	20,193
Total	2,925,262	2,858,956

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

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.

Recently Adopted Accounting Standards

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. On January 1, 2022, the Company adopted ASU 2016-12, using the modified retrospective transition method. Periods prior to January 1, 2022 have not been restated for the adoption of ASC 842 and continue to reflect the accounting treatment of leases in accordance with the prior lease accounting guidance, ASC 840, Leases. The Company adopted the new lease standard using a cumulative effect to accumulated deficit and there was no impact to accumulated deficit upon adoption. The Company elected the package of practical expedients, which among other things allowed the Company to carry forward its historical lease classification. As part of the adoption, the Company recorded operating lease liabilities of $6.4 million, operating lease ROU assets of $5.9 million, adjusted for deferred rent and lease incentive obligations of $0.5 million previously included in other non-current liabilities and accrued and other current liabilities, pertaining to its office and laboratory space operating leases.

Recent Accounting Pronouncements Not Yet Adopted

In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires the measurement of expected credit losses for financial instruments carried at amortized cost, such as accounts receivable, held at the reporting date based on historical experience, current conditions and reasonable forecasts. The main objective of this ASU is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. In November 2018, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financing Instruments-Credit Losses, which included an amendment of the effective date for nonpublic entities. For non-emerging growth companies, ASU 2016-13 is effective for fiscal years beginning after December 15, 2019. For emerging growth companies, ASU 2016-13 is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The Company adopted this pronouncement on January 1, 2023 and the impact of the provisions of this standard on its Consolidated Financial Statements is expected to be immaterial.

In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible

Instruments and Contracts in an Entity’s Own Equity, which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity’s own equity. Specifically, ASU 2020-06 simplifies accounting for the issuance of convertible instruments by removing major separation models required under current GAAP. In addition, the ASU removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and simplifies the diluted earnings per share (EPS) calculation in certain areas. ASU 2020-06 will be effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. Early adoption is permitted, beginning in fiscal years which begin after December 15, 2020, including interim periods within those fiscal years. The FASB has specified that an entity should adopt the guidance as of the beginning of its annual fiscal year. The amendment is to be adopted through either a modified retrospective or fully retrospective method of transition. The Company is currently evaluating the potential impact that the adoption of ASU 2020-06 may have on its consolidated financial statements and related disclosures.

Other Financial Information

12 Months Ended

Dec. 31, 2022

Other Financial Information [Abstract]

Other Financial Information

Prepaid Expenses and Other Current Assets

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


	December 31,
	2022		2021
Diagnostic testing supplies	$	1,795	$	1,091
Prepaid product royalties	40		49
Prepaid maintenance and insurance contracts	2,072		2,008
Other prepaid and other current assets	236		490
Prepaid and other current assets	$	4,143	$	3,638

Property and Equipment

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


	December 31,
	2022		2021
Furniture and fixtures	$	98	$	83
Laboratory equipment	5,136		4,361
Computer equipment and software	1,482		1,206
Leasehold improvements	5,223		1,151
Construction in progress	1,382		1,855
Total property and equipment	13,321		8,656
Less: accumulated depreciation and amortization	(5,124)		(3,884)
Property and equipment, net	$	8,197	$	4,772

Depreciation and amortization expense for the years ended December 31, 2022 and 2021, was approximately $1.6 million and $0.9 million, respectively. At December 31, 2022 and 2021, the gross book value of assets under finance leases was $2.8 million and $2.5 million, respectively, and is classified in "Laboratory equipment" in the table above.

Impairment of Long-Lived Assets and Goodwill

During the year ended December 31, 2022, the Company recorded an impairment charge of $0.4 million related to previously capitalized equipment used in research and development activities that were halted in the fourth quarter of 2022. The Company based the fair values of these assets on their anticipated disposal values, which is considered a Level 3 measurement. The impairment charge was classified within research and development expenses in the accompanying statements of operations.

The Company determined that the sustained decrease in its market capitalization constituted an indicator of impairment and as a result, instead of performing a qualitative test, the Company chose to proceed directly to performing a quantitative test during the fourth quarter. The Company determined the fair value of the reporting unit using the discounted cash flow (DCF) method, which is considered a Level 3 measurement. In applying the DCF

method, cash flows are estimated for a five-year financial forecast developed by management. A terminal value, which represents the value of additional cash flows into perpetuity, is also calculated. Cash flows are then discounted to present value at a discount rate commensurate with their risk. Based on this analysis, the carrying value of the reporting unit was in excess of the fair value and the goodwill was fully impaired. During the year ended December 31, 2022, the Company recorded an impairment charge of $5.5 million.

The following table presents details of the Company's goodwill for the year ended December 31, 2022 (in thousands):


	Total
Balance as of December 31, 2021	$	5,506
Goodwill impairment	(5,506)
Balance as of December 31, 2022	$	—

Accrued and Other Current Liabilities

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


	December 31,
	2022		2021
Accrued payroll and related expenses	$	2,355	$	4,048
Accrued interest	142		139
Accrued purchases of goods and services	803		510
Accrued royalties	514		180
Accrued clinical study activity	162		254
Finance lease obligations, current portion	700		587
Refund liability	445		—
Other accrued liabilities	226		1,108
Accrued and other current liabilities	$	5,347	$	6,826

Borrowings

12 Months Ended

Dec. 31, 2022

Debt Disclosure [Abstract]

Borrowings

2017 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), as amended, pursuant to which the Company has borrowed $25 million. At December 31, 2022, no additional amounts remain available to borrow under the 2017 Term Loan.

In November 2021, the Company executed the Second Amendment to the Loan and Security Agreement (the 2017 Loan Amendment). The interest rate on all borrowings under the 2017 Loan Amendment is 8.0%, of which 2.0% is paid in-kind in the form of additional term loans (PIK Loans) until December of 2024, after which interest accrues at an annual rate of 8.0%. The Company has estimated the effective interest rate of this loan to be approximately 8.5%. 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 2017 Loan Amendment will be repaid in twenty-four equal monthly installments commencing in December 2024. Upon repayment of the final installment under the 2017 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 the years ended December 31, 2022 and 2021, the Company issued PIK Loans totaling $0.6 million and $0.5 million, respectively.

The 2017 Loan Amendment requires a prepayment premium of 2% of the aggregate outstanding principal. The prepayment premium decreases by 1% on each of November 1, 2023 and 2024.

The 2017 Loan Amendment is collateralized by a first priority security interest in substantially all of the Company's assets, including intellectual property. The affirmative covenants of the 2017 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, commencing with the quarter ending December 31, 2022. 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 2017 Loan Amendment requires that the Company maintain certain levels of minimum liquidity and maintains 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, 2022, the Company was in compliance with all covenants of the 2017 Loan Amendment.

Upon an event of default in any of the 2017 Loan Amendment covenants, the repayment of the 2017 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 2017 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 2017 Loan Amendment due beyond twelve months of the balance sheet date as non-current.

2022 Equipment Notes Payable

In May 2022, the Company purchased laboratory equipment using notes payable. At December 31, 2022, the total notes payable balance related to this financed equipment was $0.8 million, with $0.2 million classified within borrowings-current portion and $0.6 million within borrowings-non-current portion, net of discounts and debt issuance costs in the accompanying balance sheets. The financed equipment is subject to a 5.28% effective interest rate and will mature on October 1, 2026.

Future Minimum Payments on the Outstanding Borrowings

As of December 31, 2022, future minimum aggregate payments, including interest, for outstanding borrowings are as follows (in thousands):


	Years Ending December 31,



2023	$	1,911
2024	3,205
2025	16,377
2026	14,973


Total	36,466
Less:
Unamortized debt discount and issuance costs	(158)
Interest	(7,340)
Total borrowings, net of discounts and debt issuance costs	28,968
Less: Borrowings-current portion	(190)
Borrowings-non-current portion, net of discounts and debt issuance costs	$	28,778

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-URI https://asc.fasb.org/topic&trid=2208564

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (h)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1C
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495334-112611

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1I
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495371-112611

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1I
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495371-112611

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (g)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1C
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495334-112611

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1C
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495334-112611

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1E
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495348-112611

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1I
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495371-112611

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (i)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

+ Details

Commitment and Contingencies

12 Months Ended

Dec. 31, 2022

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Leases

The Company adopted ASC 842, Leases, as of January 1, 2022. Prior period amounts have not been adjusted and continue to be reported in accordance with the Company's historic accounting under ASC 840, Leases.

Operating Leases

The Company leases office and laboratory spaces in Vista, California, under leases that expire in April 2027, with an option to extend portions of the leases for additional 5-year periods. The Company has not included the optional renewal periods in the measurement of the lease liabilities because it is not reasonably certain that the Company will exercise these renewal options. The Company's lease payments under each of these leases are subject to escalation clauses.

Effective on August 23, 2021, the Company entered into a sub-lease agreement for an additional office space in Carlsbad, California. The sub-lease commenced in October 2021 and expires in April 2027. The sub-lease agreement provides for monthly base rent of $66,021 which began on October 1, 2021, and such amount increases by approximately 3% annually beginning October 1, 2022.

The Company determines if a contract contains a lease at inception or modification of a contract. The Company discounts their lease obligations using its incremental borrowing rate at the commencement date. The incremental borrowing rate is the rate of interest the Company would have to pay to borrow on a collateralized basis over a similar term and amount equal to the lease payments in a similar economic environment. The Company primarily considers industry data, its credit rating and the lease term to determine its incremental borrowing rate.

Finance Leases

The Company has entered into various finance lease agreements to obtain laboratory equipment. The terms of the Company's finance leases generally range from three to five years and are typically secured by the underlying equipment. The portion of the future payments designated as principal repayments were classified as finance lease liabilities on the Company's balance sheet.

Operating and Finance Leases Balances and Costs

Operating and finance leases consist of the following (in thousands):

Lease Balance

Classification

December 31, 2022

Lease Assets

Operating

Operating lease right-of-use assets

4,885

Finance

Property and equipment, net

1,427

Lease Liabilities

Current

Operating

Operating lease liabilities

1,040

Finance

Accrued and other current liabilities

700

Non-current

Operating

Non-current operating lease liabilities

4,493

Finance

Other non-current liabilities

848

Costs associated with the Company's leases were included in the statements of operations as follows (in thousands):


Lease Cost	Year Ended December 31, 2022
Operating leases
Operating lease cost(1)	$	1,540
Finance lease cost
Amortization of lease assets	679
Interest on finance lease liabilities	80
Total lease cost	$	2,299

(1) Includes variable lease cost of $165,000 for the year ended December 31, 2022.

Supplemental cash flow information on leases is as follows (in thousands):


Cash paid for amounts included in the measurement of lease liabilities	Year Ended December 31, 2022
Operating cash out flows from operating leases	$	1,262
Operating cash out flows from interest paid on finance leases	$	80
Financing cash out flows from finance leases	$	667

Information regarding the weighted-average lease term and weighted average discount rate are as follows:


	December 31, 2022
Weighted-average remaining lease term (years)
Operating leases	4.3
Finance leases	1.94
Weighted-average discount rate
Operating leases	8.0	%
Finance leases	4.8	%

Future payments under operating and finance leases as of December 31, 2022 are as follows (in thousands):


	Operating Leases		Finance Leases

2023	$	1,446	$	828
2024	1,489		574
2025	1,533		248
2026	1,584		147
Thereafter	539		29
Total minimum lease payments	6,591		1,826
Less: imputed interest	(1,058)		(278)
Total lease liabilities	5,533		1,548
Less: current portion	(1,040)		(700)
Lease obligations, net of current portion	$	4,493	$	848

Disclosures Under ASC 840

Minimum annual lease payments under non-cancelable operating lease arrangements as of December 31, 2021 are as follows (in thousands):


Years Ending December 31,	Operating Leases
2022	$	1,337
2023	1,445
2024	1,489
2025	1,533
2026	1,584
Thereafter	539
Total minimum lease payments	$	7,927

For the year ended December 31, 2021, rent expense was $0.9 million.

Acquisition-related liabilities

In connection with the acquisition of the medical diagnostics division of Royalty Pharma Collection Trust (Royalty Pharma) (formerly known as 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, for which the obligations no longer exist at December 31, 2022.

In addition, the Company has ongoing royalty payment obligations with Royalty Pharma of 2.5% on net sales of products which incorporate certain acquired technologies. Future royalties payable under these arrangements are limited to the lesser of (i) an aggregate of $1.2 million (including an upfront payment of $0.1 million) and (ii) 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, individual license agreements generally provide for ongoing royalty payments ranging from 1.5% to 7.0% on net sales of products which incorporate licensed technology, as defined in such agreements. Royalties are accrued when earned and recorded in costs of revenue in the accompanying statement of operations.

In May 2021, the Company entered into an exclusive license agreement with Allegheny Health Network Research Institute (AHN) to obtain an exclusive license to AHN's patent rights in certain inventions, pursuant to which the Company paid AHN an initial license fee of $0.4 million. In addition, under the terms of the exclusive license agreement, the Company is required to pay the greater of royalties in the low single digits on net sales of diagnostic tests using the assigned patents or a flat annual minimum royalty amount, pending approvals and commercialization.

In November 2021, the Company entered into an exclusive license agreement with Queen Mary University of London (QMUL) to obtain an exclusive license to QMUL's patent rights in certain inventions, pursuant to which the Company paid QMUL an initial license fee of $0.4 million. The Company is obligated to make a one-time payment of $0.1 million relating to the first commercial sale of the licensed products. In addition, after the first 18 months of commercial sales under the terms of the exclusive license agreement, the Company is required to pay royalties in the high single-digits on net sales of testing products using the assigned patents, pending approvals and commercialization.

Supply Agreement

In December 2021, the Company entered into an amended supply agreement with one supplier for reagents which includes minimum annual purchase commitments of $6.0 million and $6.9 million for the years ended December 31, 2022 and 2023, respectively, with a 15% annual increase thereafter for unconditional minimum purchase commitments through the year ending December 31, 2025.

Collaboration Obligations

In May 2021, the Company entered into a master research collaboration agreement with AHN, pursuant to which the Company is required to pay AHN a collaboration fee of $0.4 million for each year during the initial term of the agreement. Collaboration expenses under the master research collaboration agreement were $0.4 million for the year ended December 31, 2022. Collaboration expenses under the AHN collaboration are included in research and development expenses.

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 for subpoenas and other civil investigative demands, from governmental agencies, Medicare or Medicaid 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 that 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. The Company does not believe the outcome of any such matters will have a material effect on its financial position or results of operations.

Fair Value Measurements

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value Measurements

The carrying value of the Company's cash, cash equivalents and restricted cash, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued and other current liabilities approximate their fair values due to their short-term nature, which are determined to be a Level 1 measurement. The estimated fair values of the Company's long-term borrowings are determined by Level 2 inputs and are based primarily on quoted market prices for the same or similar issues. As of December 31, 2022, the 2017 Term Loan had a carrying value of $28.3 million and a fair value of $26.9 million. The estimated fair value of the 2017 Term Loan, which uses Level 2 fair value inputs, was determined based on a discounted cash flow approach using available market information on discount and borrowing rates with similar terms, maturities, and credit ratings. The recorded value of the Company's long-term borrowings as of December 31, 2021 approximated their fair values as the interest rate and other terms were that which were available to the Company at the time. See footnote 3 for discussion of recorded impairment charges related to long-lived assets and goodwill.

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.

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, 2022
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds, included in cash and cash equivalents	$	29,438	$	29,438	$	—	$	—
Certificate of deposit, included in cash and cash equivalents	30,100		30,100		—		—
Total	$	59,538	$	59,538	$	—	$	—


	December 31, 2021
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds, included in cash and cash equivalents	$	95,761	$	95,761	$	—	$	—

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

Stockholders' Equity

12 Months Ended

Dec. 31, 2022

Equity [Abstract]

Stockholders' Equity

Common Stock

Shelf Registration Statement

On November 10, 2020, the Company filed a registration statement on Form S-3 (the Shelf Registration Statement), covering the offering, from time to time, of up to $150.0 million of common stock, preferred stock, debt securities, warrants and units, which Shelf Registration Statement became effective on November 19, 2020.

On March 25, 2021, the Company completed a public offering of 4,255,000 shares of its common stock at a public offering price of $16.25 per share. Net proceeds from the offering were approximately $64.7 million, after deducting underwriting discounts, commissions and other offering expenses of $4.4 million. The shares were registered pursuant to the Company's Shelf Registration Statement discussed above.

At The Market Sales Agreement

On September 15, 2022, the Company entered into a sales agreement (the Sales Agreement) with Cowen and Company, LLC, as sales agent, pursuant to which the Company may offer and sell, from time to time, shares of Company common stock having an aggregate offering price of up to $50.0 million. The Company is not obligated to sell any shares of Company common stock in the offering. As of December 31, 2022, the Company has not sold any shares of its common stock pursuant to the Sales Agreement.

Exchange Agreement

On June 22, 2021, the Company entered into an exchange agreement (the Exchange Agreement) with an investor and its affiliates (the Exchanging Stockholders), pursuant to which the Company exchanged an aggregate of 804,951 shares of the Company's common stock owned by the Exchanging Stockholders for pre-funded warrants (the Exchange Warrants) to purchase an aggregate of 804,951 shares of common stock (subject to adjustment in the event of any stock dividends and splits, reverse stock split, recapitalization, reorganization or similar transaction, as described in the Exchange Warrants), with an exercise price of $0.001 per share. The Exchange Warrants do not expire and are exercisable at any time except that the Exchange Warrants cannot be exercised by the Exchanging Stockholders if, after giving effect thereto, the Exchanging Stockholders would beneficially own more than 4.99% of the Company's common stock, which percentage may change at the Exchanging Stockholder's election to any other percentage upon 61 days' notice to the Company. The Company recorded the retirement of common stock exchanged as a reduction of common shares outstanding and additional paid-in-capital at the fair value of the Exchange Warrants on the issuance date. The Exchange Warrants are classified as equity and the fair value of the Exchange Warrants was recorded as an increase to additional paid-in-capital and is not subject to remeasurement. The Company determined that the fair value of the Exchange Warrants is substantially similar to the fair value of the retired shares on the issuance date due to the negligible exercise price for the Exchange Warrants. As of December 31, 2022, none of the Exchange Warrants have been exercised.

Outstanding Warrants

The following equity classified warrants to purchase common stock were outstanding as of December 31, 2022:

Exercise Price

Issuance date

Expiration date

Common stock warrants

237,169

1.84

January 19, 2016

January 19, 2026

Common stock warrants

67,086

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

Common stock warrants (Exchange Warrants)

804,951

0.001

June 22, 2021

None

1,214,059

During the year ended December 31, 2022, no warrants to purchase common stock were exercised.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

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+ Details

Stock Option Plan

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Stock Option Plan

2019 Incentive Award Plan

In September 2019, the Company's Board of Directors adopted, and the Company's stockholders approved, the 2019 Plan. Under the 2019 Plan, which expires in September 2029, 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 or, for grants to new hires, date of hire. 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, 2022, 1,452,435 shares remained available for future awards. Under the evergreen provision, on January 1, 2023, an additional 661,999 shares became available for issuance under the 2019 Plan.

2019 Employee Stock Purchase Plan

In September 2019, the Board of Directors adopted, and the Company's stockholders approved, 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. The number of shares of common stock available for issuance under the ESPP will be annually increased on the first day of each calendar year during the term of the ESPP through January 1, 2029 in an amount equal to the lesser of (i) 1% of the outstanding capital stock on each December 31st, or (ii) such lesser amount determined by the Board of Directors. As of December 31, 2022, 413,425 shares of common stock remained available for issuance under the ESPP. Under the evergreen provision, on January 1, 2023, an additional 165,500 shares became available for issuances under the ESPP.

Stock Options

Stock option activity under the Company's 2019 Plan is set forth below:


	Number of Options	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Outstanding, December 31, 2021	2,014,330	$	12.10	7.87	$	5,428
Granted	63,000	$	5.25
Exercised	(245,186)	$	0.26
Forfeited	(257,982)	$	16.09
Expired	(152,927)	$	13.73
Outstanding, December 31, 2022	1,421,235	$	12.94	7.09	$	483
Vested and expected to vest, December 31, 2022	1,421,235	$	12.94	7.09	$	483
Options exercisable, December 31, 2022	1,129,333	$	12.94	6.89	$	483

The weighted-average grant date fair value per share of employee options granted to employees during the years ended December 31, 2022 and 2021 was $2.74 and $8.83, 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 was $2.40 and $11.63 per share at December 31, 2022 and 2021, respectively. The intrinsic value of options exercised for the years ended December 31, 2022 and 2021 was $0.6 million and $0.1 million, respectively. As of December 31, 2022, total unrecognized compensation cost related to option awards was $1.8 million, which is expected to be recognized over a remaining weighted-average vesting period of 1.1 years.

Restricted Stock Units

Restricted stock unit activity under the Company's 2019 Plan is set forth below:


	Number of Shares	Weighted- Average Grant Date Fair Value		Aggregate Intrinsic Value
Outstanding, December 31, 2021	415,325	$	16.54	$	4,830
Awards granted	1,076,725	$	5.89
Awards released	(100,586)	$	16.55
Awards canceled	(355,256)	$	11.29
Outstanding, December 31, 2022	1,036,208	$	7.28	$	2,487

As of December 31, 2022, all of the outstanding restricted stock units are unvested. The fair value of restricted stock units vested in the year ended December 31, 2022 was $0.7 million. No restricted stock units vested in the year ended December 31, 2021. The weighted average grant date fair value for restricted stock units granted during the years ended December 31, 2022 and 2021 was $5.89 and $16.53, respectively. As of December 31, 2022, total unrecognized compensation cost related to restricted stock units was $6.0 million, which is expected to be recognized over a remaining weighted-average vesting period of 3.3 years.

Stock-Based Compensation Expense

Stock Options

The fair value of employee stock options was estimated using the following assumptions in the Black-Scholes options pricing model to determine the fair value of stock options granted:


	Year Ended December 31,
	2022	2021
Expected volatility	54%	56%-60%
Risk-free interest rate	3.4%	0.8%-1.1%
Dividend yield	—	—
Expected term (in years)	5.5	5.5-6.1

Employee Stock Purchase Plan

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


	Year Ended December 31,
	2022	2021
Expected volatility	45%-57%	45%-60%
Risk-free interest rate	0.6%-3.3%	0.1%
Dividend yield	—	—
Expected term (in years)	0.5	0.5

Stock-based compensation expense related to the ESPP for the years ended December 31, 2022 and 2021 was less than $0.1 million and $0.2 million, respectively. As of December 31, 2022, total unrecognized compensation cost related to stock purchase rights granted under the ESPP was less than $0.1 million, which is expected to be recognized over a remaining weighted-average vesting period of 0.2 years.

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


	Year Ended December 31,
	2022		2021
Cost of revenue	$	213	$	164
Selling, general and administrative	3,860		3,943
Research and development	631		621
Total	$	4,704	$	4,728

Common stock reserved for future issuance consists of the following at December 31, 2022:


Warrants to purchase common stock						1,214,059
Common stock option grants issued and outstanding						1,421,235
Common stock reserved for issuance upon vesting of outstanding restricted stock units						1,036,370
Common shares available for grant under the 2019 Plan						1,452,435
Common shares available for future issuance under ESPP						413,425
Total						5,537,524

Income Taxes

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Income Taxes

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


	Year Ended December 31,
	2022		2021
Current:
Federal	$	—	$	—
State	24		27
Total current	24		27
Deferred:
Federal	(137)		137
State	(169)		11
Total deferred	(306)		148
Provision (benefit) for income tax	$	(282)	$	175

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


	Year Ended December 31,
	2022		2021
Federal statutory tax rate	(21.0)	%	(21.0)	%
State income taxes, net of federal tax benefits	(4.3)	%	(3.8)	%
Research and development tax credits	(1.5)	%	(1.2)	%
Stock compensation	1.4	%	0.9	%
Non-deductible expenses	0.9	%	1.1	%
Change in valuation allowance	23.9	%	24.6	%
Effective tax rate	(0.6)	%	0.6	%

Significant components of the Company’s deferred tax assets at December 31, 2022 and 2021 are shown below (in thousands). 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.


	December 31,
	2022		2021
Deferred tax assets:
Net operating loss carryforwards	$	29,789	$	22,365
Research and development tax credits	2,216		1,102
Accruals, reserves and other	349		1,055
Interest expense	2,236		1,953
Indefinite lived assets	362		—
Stock compensation	1,606		1,407
Lease liability	1,374		—
Capitalization of research and experimentation costs	2,047		—
Total gross deferred tax assets	39,979		27,882
Less: valuation allowance	(38,567)		(27,158)
Deferred tax assets, net	1,412		724
Deferred tax liabilities:
Financing and acquisition-related liabilities	—		(335)
Indefinite lived assets	—		(521)
Right of use assets	(1,206)		—
Basis differences in fixed and intangible assets	(206)		(175)
Deferred tax liabilities, net	(1,412)		(1,031)
Net deferred tax liabilities	$	—	$	(307)

Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2022 and 2021, which related primarily to increases in net operating loss (NOL) carryforwards, research and development tax credits, capitalization of research and experimentation costs, and impairment of goodwill were as follows (in thousands):


	December 31,
	2022		2021
Valuation allowance at the beginning of the year	$	27,158	$	20,596
Increases recorded to income tax provision	11,409		6,562
Valuation allowance at the end of the year	$	38,567	$	27,158

At December 31, 2022 and 2021, the Company had federal NOL carryforwards of approximately $118.4 million and $89.4 million, respectively. At December 31, 2022 and 2021, the Company had state NOL carryforwards of $87.0 million and $61.0 million, respectively. Approximately $43.5 million of the federal tax loss carryforwards will begin to expire in 2023, unless previously utilized. The federal NOL carryforwards generated in after December 31, 2017 of $74.9 million will carryforward indefinitely. The Company’s state tax loss carryforwards will expire in 2030, unless previously utilized.

At December 31, 2022, the Company's deferred tax assets are primarily comprised of federal and state tax NOL 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.

The Company is subject to taxation in the United States and in various state jurisdictions. The Company’s tax years for 2003 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 material accruals for, and did not recognize any, material interest or penalties in these financial statements in any period presented.

Uncertain Tax Positions

At December 31, 2022 and 2021, 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

401(k) Plan	12 Months Ended
401(k) Plan	Dec. 31, 2022
Retirement Benefits [Abstract]
401(k) Plan	401(k) PlanThe 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, 2022 and 2021, the Company made contributions to the Plan at 4% and 3% of qualified employee compensation, respectively. For the years ended December 31, 2022 and 2021, these contributions totaled approximately $0.9 million and $0.5 million, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

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+ Details

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2022
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. We have not experienced any losses on our cash or cash equivalents.
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 EquipmentProperty 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 operating expenses 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 and operating lease assets (see Note 5). We amortize all finite lived intangible assets over their respective estimated useful lives. Operating lease assets are amortized over the term of the leases. In considering whether long-lived assets are impaired, we combine our intangible assets and other long-lived assets (excluding goodwill), into groupings, a determination which we principally make on the basis of whether the assets are specific to a particular test offered by us or technology we are developing. 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. Management’s estimates of future cash flows are impacted by projected test volume and levels of reimbursement, as well as expectations related to the future cost structure of the entity. 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. During the year ended December 31, 2022, the Company recorded an impairment charge to fixed assets totaling $0.4 million (see Note 3). The impairment charge was classified within research and development expenses in the accompanying statements of operations. Goodwill 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. During the year ended December 31, 2022, the Company recorded an impairment charge to goodwill totaling $5.5 million (see Note 3).
Leases	Leases The Company categorizes leases at their commencement as either operating or finance leases. Effective January 1, 2022 upon the adoption of Accounting Standards Codification (ASC) 842, the Company recognizes operating lease ROU assets and operating lease liabilities for each lease arrangement identified. Lease liabilities are recorded at the present value of future lease payments discounted using the Company's incremental borrowing rate for the lease established at the commencement date. ROU assets are measured at the amount of the lease liability plus any initial direct costs, less any lease incentives received before commencement. Lease expense is recognized as a single lease cost over the lease term on a straight-line basis. The Company has elected not to apply the recognition requirements to short-term leases and not to separate non-lease components from lease components for its leases.
Clinical Studies	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 based on estimated progress of services performed, including actual level of subjects enrolled and progress of the clinical studies. Payments made prior to the completion of clinical study services are capitalized as a prepaid expense. The prepaid amounts are expensed as the related goods are delivered or the services are performed, or when it is no longer expected that the goods will be delivered or the services rendered. Expenses associated with clinical study activities are recorded in research and development expenses in the accompanying statement of operations.
Revenue Recognition and Shipping and Handling Costs	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 (each, a payor) consist of commercial payors (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, are recorded upon settlement. Included in revenues for the years ended December 31, 2022 and 2021 was a net revenue decrease of $2.4 million and a net revenue increase of $0.7 million, respectively, associated with changes in estimated variable consideration related to performance obligations satisfied in previous periods. The transaction price is estimated using an expected value method on a portfolio basis. Variable consideration is included in the transaction price only to the extent it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainties with respect to the amount are resolved. The Company's portfolios are grouped per payor (i.e. each individual commercial payor, Medicare, Medicaid, client payors, patient self-pay, etc.) and per test. Consideration may be constrained and excluded from the transaction price in situations where there is no contractually agreed upon reimbursement coverage or in absence of a predictable pattern and history of collectability with a payor. Accordingly, in such situations revenues are recognized on the basis of actual cash collections. Additionally, from time to time, the Company may issue refunds to payors for overpayments or amounts billed in error. Any refunds are accounted for as reductions in revenues in the statement of operations as an element of variable consideration. The estimated expected refunds are accrued as a liability on the Company’s balance sheet. 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 (as amended from time to time, the Janssen Agreement) with Janssen Biotech, Inc. (Janssen) to co-promote SIMPONI® in the United States. In August 2021, the Company and Janssen mutually agreed to terminate the Janssen Agreement, effective August 31, 2021. Pursuant to the Janssen Agreement, as amended, the Company was responsible for the costs associated with its sales force over the course of such co-promotion. Janssen was 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 was 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. The Company's obligations relating to sales and co-promotion services for SIMPONI® were a series of single performance obligations since Janssen simultaneously received and consumed benefits provided by the Company's sales and co-promotional services. The method for measuring progress towards satisfying the performance obligations was based on prescribed units in excess of the contractual baseline at the contractual rate earned per unit. The Company recognized no co-promotion revenue and $1.2 million in co-promotion revenue during the years ended December 31, 2022 and December 31, 2021, respectively. The related expenses for marketing SIMPONI® were included in selling, general and administrative expenses and were expensed as incurred. Pursuant to the terms of the termination, the Company received $0.6 million in consideration (which was earned in the year ended December 31, 2021) and the Company was restricted until May 31, 2022 from promoting any other biologic or Janus kinase inhibitor used for the treatment of indications covered by the Janssen Agreement without first obtaining Janssen's written consent. The restriction no longer applies. 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 $2.7 million and $2.1 million, for the years ended December 31, 2022 and 2021, respectively.
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 $3.0 million and $1.7 million for the years ended December 31, 2022 and 2021, 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 Company's 2019 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 inputs, including the fair value of the Company's common stock, expected volatility, expected term and risk-free interest rates. Volatility is based on the Company's historical calculated volatility since being publicly traded. The weighted-average expected term of options was calculated using the simplified method. 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 is zero, as the Company has never declared or paid dividends and has no plans to do so in the foreseeable future. The fair value of each restricted stock unit is determined on the grant date using the closing price of the Company's common stock on that date. The Company's restricted stock units generally vest in equal annual installments over four years from the date of grant or, for grants to new hires, date of hire. Vesting of restricted stock units is subject to the holder's continued service with the Company. The Company issues new shares to satisfy restricted stock units upon vesting.
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 shares and common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. The weighted-average number of shares used to compute basic and diluted shares includes shares issuable upon the exercise of pre-funded warrants at a nominal price. Potentially dilutive common stock equivalents are comprised of warrants for the purchase of common stock, options and restricted stock units outstanding under the Company's 2019 Incentive Award Plan (the 2019 Plan) and shares of the Company's common stock pursuant to the ESPP. For the years ended December 31, 2022 and 2021, 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 Recently Adopted Accounting Standards Not Yet Adopted	Recent Accounting Pronouncements 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. Recently Adopted Accounting Standards 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. On January 1, 2022, the Company adopted ASU 2016-12, using the modified retrospective transition method. Periods prior to January 1, 2022 have not been restated for the adoption of ASC 842 and continue to reflect the accounting treatment of leases in accordance with the prior lease accounting guidance, ASC 840, Leases. The Company adopted the new lease standard using a cumulative effect to accumulated deficit and there was no impact to accumulated deficit upon adoption. The Company elected the package of practical expedients, which among other things allowed the Company to carry forward its historical lease classification. As part of the adoption, the Company recorded operating lease liabilities of $6.4 million, operating lease ROU assets of $5.9 million, adjusted for deferred rent and lease incentive obligations of $0.5 million previously included in other non-current liabilities and accrued and other current liabilities, pertaining to its office and laboratory space operating leases. Recent Accounting Pronouncements Not Yet Adopted In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires the measurement of expected credit losses for financial instruments carried at amortized cost, such as accounts receivable, held at the reporting date based on historical experience, current conditions and reasonable forecasts. The main objective of this ASU is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. In November 2018, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financing Instruments-Credit Losses, which included an amendment of the effective date for nonpublic entities. For non-emerging growth companies, ASU 2016-13 is effective for fiscal years beginning after December 15, 2019. For emerging growth companies, ASU 2016-13 is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The Company adopted this pronouncement on January 1, 2023 and the impact of the provisions of this standard on its Consolidated Financial Statements is expected to be immaterial. In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity, which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity’s own equity. Specifically, ASU 2020-06 simplifies accounting for the issuance of convertible instruments by removing major separation models required under current GAAP. In addition, the ASU removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and simplifies the diluted earnings per share (EPS) calculation in certain areas. ASU 2020-06 will be effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. Early adoption is permitted, beginning in fiscal years which begin after December 15, 2020, including interim periods within those fiscal years. The FASB has specified that an entity should adopt the guidance as of the beginning of its annual fiscal year. The amendment is to be adopted through either a modified retrospective or fully retrospective method of transition. The Company is currently evaluating the potential impact that the adoption of ASU 2020-06 may have on its consolidated financial statements and related disclosures.
Fair Value Measurements	The carrying value of the Company's cash, cash equivalents and restricted cash, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued and other current liabilities approximate their fair values due to their short-term nature, which are determined to be a Level 1 measurement. The estimated fair values of the Company's long-term borrowings are determined by Level 2 inputs and are based primarily on quoted market prices for the same or similar issues. As of December 31, 2022, the 2017 Term Loan had a carrying value of $28.3 million and a fair value of $26.9 million. The estimated fair value of the 2017 Term Loan, which uses Level 2 fair value inputs, was determined based on a discounted cash flow approach using available market information on discount and borrowing rates with similar terms, maturities, and credit ratings. The recorded value of the Company's long-term borrowings as of December 31, 2021 approximated their fair values as the interest rate and other terms were that which were available to the Company at the time. See footnote 3 for discussion of recorded impairment charges related to long-lived assets and goodwill. 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.

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

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

For each significant payor and customer,

revenue as a percentage of total revenue and accounts receivable as a percentage of total accounts receivable are as follows:


	Revenue
	Year Ended December 31,
	2022		2021
Medicare	39	%	19	%
Medicare Advantage	15	%	13	%
Blue Shield	*		12	%



*						Less than 10%.


	Accounts Receivable
	December 31,
	2022		2021
Medicare	21	%	*
Medicare Advantage	13	%	*
Blue Shield	*		19	%
United Healthcare	*		18	%



*						Less than 10%.

Disaggregation of Revenue

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


	Year Ended December 31,
	2022		2021
Revenue:
Commercial	$	18,975	$	27,499
Government	17,687		9,221
Client(1)	7,928		9,288
Other(2)	973		1,091
Janssen (SIMPONI®)	—		1,200
Total revenue	$	45,563	$	48,299

(1)Includes hospitals, other laboratories, etc.

(2)Includes patient self-pay.

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,
	2022		2021
Cash and cash equivalents	$	62,391	$	99,442
Restricted cash	200		100
	$	62,591	$	99,542

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,
	2022		2021
Cash and cash equivalents	$	62,391	$	99,442
Restricted cash	200		100
	$	62,591	$	99,542

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,
	2022	2021


Warrants to purchase common stock	409,108	409,108
Common stock options	1,421,235	2,014,330
Restricted stock units	1,036,208	415,325
Employee stock purchase plan	58,711	20,193
Total	2,925,262	2,858,956

Other Financial Information (Tables)

12 Months Ended

Dec. 31, 2022

Other Financial Information [Abstract]

Prepaid Expenses and Other Current Assets

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


	December 31,
	2022		2021
Diagnostic testing supplies	$	1,795	$	1,091
Prepaid product royalties	40		49
Prepaid maintenance and insurance contracts	2,072		2,008
Other prepaid and other current assets	236		490
Prepaid and other current assets	$	4,143	$	3,638

Property and Equipment

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


	December 31,
	2022		2021
Furniture and fixtures	$	98	$	83
Laboratory equipment	5,136		4,361
Computer equipment and software	1,482		1,206
Leasehold improvements	5,223		1,151
Construction in progress	1,382		1,855
Total property and equipment	13,321		8,656
Less: accumulated depreciation and amortization	(5,124)		(3,884)
Property and equipment, net	$	8,197	$	4,772

Schedule of Goodwill

The following table presents details of the Company's goodwill for the year ended December 31, 2022 (in thousands):


	Total
Balance as of December 31, 2021	$	5,506
Goodwill impairment	(5,506)
Balance as of December 31, 2022	$	—

Accrued and Other Current Liabilities

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


	December 31,
	2022		2021
Accrued payroll and related expenses	$	2,355	$	4,048
Accrued interest	142		139
Accrued purchases of goods and services	803		510
Accrued royalties	514		180
Accrued clinical study activity	162		254
Finance lease obligations, current portion	700		587
Refund liability	445		—
Other accrued liabilities	226		1,108
Accrued and other current liabilities	$	5,347	$	6,826

- Definition

Tabular disclosure of goodwill by reportable segment and in total which includes a rollforward schedule.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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-Section 50
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-Subparagraph (g)
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
-Topic 350
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Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
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-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13854-109267

Reference 11: http://www.xbrl.org/2003/role/exampleRef
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Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
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+ Details

Borrowings (Tables)

12 Months Ended

Dec. 31, 2022

Debt Disclosure [Abstract]

Schedule of Future Minimum Aggregate Payments for Outstanding Borrowings

As of December 31, 2022, future minimum aggregate payments, including interest, for outstanding borrowings are as follows (in thousands):


	Years Ending December 31,



2023	$	1,911
2024	3,205
2025	16,377
2026	14,973


Total	36,466
Less:
Unamortized debt discount and issuance costs	(158)
Interest	(7,340)
Total borrowings, net of discounts and debt issuance costs	28,968
Less: Borrowings-current portion	(190)
Borrowings-non-current portion, net of discounts and debt issuance costs	$	28,778

Commitment and Contingencies (Tables)

12 Months Ended

Dec. 31, 2022

Commitments and Contingencies Disclosure [Abstract]

Summary of Lease Costs

Operating and finance leases consist of the following (in thousands):

Lease Balance

Classification

December 31, 2022

Lease Assets

Operating

Operating lease right-of-use assets

4,885

Finance

Property and equipment, net

1,427

Lease Liabilities

Current

Operating

Operating lease liabilities

1,040

Finance

Accrued and other current liabilities

700

Non-current

Operating

Non-current operating lease liabilities

4,493

Finance

Other non-current liabilities

848

Costs associated with the Company's leases were included in the statements of operations as follows (in thousands):


Lease Cost	Year Ended December 31, 2022
Operating leases
Operating lease cost(1)	$	1,540
Finance lease cost
Amortization of lease assets	679
Interest on finance lease liabilities	80
Total lease cost	$	2,299

(1) Includes variable lease cost of $165,000 for the year ended December 31, 2022.

Supplemental cash flow information on leases is as follows (in thousands):


Cash paid for amounts included in the measurement of lease liabilities	Year Ended December 31, 2022
Operating cash out flows from operating leases	$	1,262
Operating cash out flows from interest paid on finance leases	$	80
Financing cash out flows from finance leases	$	667

Information regarding the weighted-average lease term and weighted average discount rate are as follows:


	December 31, 2022
Weighted-average remaining lease term (years)
Operating leases	4.3
Finance leases	1.94
Weighted-average discount rate
Operating leases	8.0	%
Finance leases	4.8	%

Summary of Lessee, Operating Lease, Liability, Maturity

Future payments under operating and finance leases as of December 31, 2022 are as follows (in thousands):


	Operating Leases		Finance Leases

2023	$	1,446	$	828
2024	1,489		574
2025	1,533		248
2026	1,584		147
Thereafter	539		29
Total minimum lease payments	6,591		1,826
Less: imputed interest	(1,058)		(278)
Total lease liabilities	5,533		1,548
Less: current portion	(1,040)		(700)
Lease obligations, net of current portion	$	4,493	$	848

Summary of Finance Lease, Liability, Maturity

Future payments under operating and finance leases as of December 31, 2022 are as follows (in thousands):


	Operating Leases		Finance Leases

2023	$	1,446	$	828
2024	1,489		574
2025	1,533		248
2026	1,584		147
Thereafter	539		29
Total minimum lease payments	6,591		1,826
Less: imputed interest	(1,058)		(278)
Total lease liabilities	5,533		1,548
Less: current portion	(1,040)		(700)
Lease obligations, net of current portion	$	4,493	$	848

Schedule of Future Minimum Rental Payments for Operating Leases

Minimum annual lease payments under non-cancelable operating lease arrangements as of December 31, 2021 are as follows (in thousands):


Years Ending December 31,	Operating Leases
2022	$	1,337
2023	1,445
2024	1,489
2025	1,533
2026	1,584
Thereafter	539
Total minimum lease payments	$	7,927

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2022

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, 2022
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds, included in cash and cash equivalents	$	29,438	$	29,438	$	—	$	—
Certificate of deposit, included in cash and cash equivalents	30,100		30,100		—		—
Total	$	59,538	$	59,538	$	—	$	—


	December 31, 2021
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds, included in cash and cash equivalents	$	95,761	$	95,761	$	—	$	—

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2022

Equity [Abstract]

Schedule of Outstanding Warrants

The following equity classified warrants to purchase common stock were outstanding as of December 31, 2022:

Exercise Price

Issuance date

Expiration date

Common stock warrants

237,169

1.84

January 19, 2016

January 19, 2026

Common stock warrants

67,086

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

Common stock warrants (Exchange Warrants)

804,951

0.001

June 22, 2021

None

1,214,059

Stock Option Plan (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Stock Option Activity

Stock option activity under the Company's 2019 Plan is set forth below:


	Number of Options	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Outstanding, December 31, 2021	2,014,330	$	12.10	7.87	$	5,428
Granted	63,000	$	5.25
Exercised	(245,186)	$	0.26
Forfeited	(257,982)	$	16.09
Expired	(152,927)	$	13.73
Outstanding, December 31, 2022	1,421,235	$	12.94	7.09	$	483
Vested and expected to vest, December 31, 2022	1,421,235	$	12.94	7.09	$	483
Options exercisable, December 31, 2022	1,129,333	$	12.94	6.89	$	483

Schedule of Share-based Payment Arrangement, Restricted Stock Unit, Activity

Restricted stock unit activity under the Company's 2019 Plan is set forth below:


	Number of Shares	Weighted- Average Grant Date Fair Value		Aggregate Intrinsic Value
Outstanding, December 31, 2021	415,325	$	16.54	$	4,830
Awards granted	1,076,725	$	5.89
Awards released	(100,586)	$	16.55
Awards canceled	(355,256)	$	11.29
Outstanding, December 31, 2022	1,036,208	$	7.28	$	2,487

Schedule of Fair Value Assumptions, Stock Options

The fair value of employee stock options was estimated using the following assumptions in the Black-Scholes options pricing model to determine the fair value of stock options granted:


	Year Ended December 31,
	2022	2021
Expected volatility	54%	56%-60%
Risk-free interest rate	3.4%	0.8%-1.1%
Dividend yield	—	—
Expected term (in years)	5.5	5.5-6.1

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


	Year Ended December 31,
	2022	2021
Expected volatility	45%-57%	45%-60%
Risk-free interest rate	0.6%-3.3%	0.1%
Dividend yield	—	—
Expected term (in years)	0.5	0.5

Schedule of Non-cash Stock-based Compensation Expense


	Year Ended December 31,
	2022		2021
Cost of revenue	$	213	$	164
Selling, general and administrative	3,860		3,943
Research and development	631		621
Total	$	4,704	$	4,728

Schedule of Common Stock Reserved For Future Issuance

Common stock reserved for future issuance consists of the following at December 31, 2022:


Warrants to purchase common stock						1,214,059
Common stock option grants issued and outstanding						1,421,235
Common stock reserved for issuance upon vesting of outstanding restricted stock units						1,036,370
Common shares available for grant under the 2019 Plan						1,452,435
Common shares available for future issuance under ESPP						413,425
Total						5,537,524

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit)

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


	Year Ended December 31,
	2022		2021
Current:
Federal	$	—	$	—
State	24		27
Total current	24		27
Deferred:
Federal	(137)		137
State	(169)		11
Total deferred	(306)		148
Provision (benefit) for income tax	$	(282)	$	175

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:


	Year Ended December 31,
	2022		2021
Federal statutory tax rate	(21.0)	%	(21.0)	%
State income taxes, net of federal tax benefits	(4.3)	%	(3.8)	%
Research and development tax credits	(1.5)	%	(1.2)	%
Stock compensation	1.4	%	0.9	%
Non-deductible expenses	0.9	%	1.1	%
Change in valuation allowance	23.9	%	24.6	%
Effective tax rate	(0.6)	%	0.6	%

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.


	December 31,
	2022		2021
Deferred tax assets:
Net operating loss carryforwards	$	29,789	$	22,365
Research and development tax credits	2,216		1,102
Accruals, reserves and other	349		1,055
Interest expense	2,236		1,953
Indefinite lived assets	362		—
Stock compensation	1,606		1,407
Lease liability	1,374		—
Capitalization of research and experimentation costs	2,047		—
Total gross deferred tax assets	39,979		27,882
Less: valuation allowance	(38,567)		(27,158)
Deferred tax assets, net	1,412		724
Deferred tax liabilities:
Financing and acquisition-related liabilities	—		(335)
Indefinite lived assets	—		(521)
Right of use assets	(1,206)		—
Basis differences in fixed and intangible assets	(206)		(175)
Deferred tax liabilities, net	(1,412)		(1,031)
Net deferred tax liabilities	$	—	$	(307)

Summary of Valuation Allowance


	December 31,
	2022		2021
Valuation allowance at the beginning of the year	$	27,158	$	20,596
Increases recorded to income tax provision	11,409		6,562
Valuation allowance at the end of the year	$	38,567	$	27,158

Organization (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 62,391	$ 99,442
Accumulated deficit	$ 255,527	$ 208,140

Summary of Significant Accounting Policies - Revenue by Major Payers (Details) - Customer Concentration Risk	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Medicare \| Revenue Benchmark
Disaggregation of Revenue [Line Items]
Concentration risk percentage	39.00%	19.00%
Medicare \| Receivable Benchmark
Disaggregation of Revenue [Line Items]
Concentration risk percentage	21.00%
Medicare Advantage \| Revenue Benchmark
Disaggregation of Revenue [Line Items]
Concentration risk percentage	15.00%	13.00%
Medicare Advantage \| Receivable Benchmark
Disaggregation of Revenue [Line Items]
Concentration risk percentage	13.00%
Blue Shield \| Revenue Benchmark
Disaggregation of Revenue [Line Items]
Concentration risk percentage		12.00%
Blue Shield \| Receivable Benchmark
Disaggregation of Revenue [Line Items]
Concentration risk percentage		19.00%
United Healthcare \| Receivable Benchmark
Disaggregation of Revenue [Line Items]
Concentration risk percentage		18.00%

Summary of Significant Accounting Policies - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) installment segment	Dec. 31, 2021 USD ($)	Jan. 01, 2022 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash	$ 200	$ 100
Long-lived assets impairment	397	0
Goodwill Impairment	5,506	0
Revenue recognized	(2,400)	700
Revenue	45,563	48,299
Advertising and marketing costs	$ 3,000	1,700
Dividend yield	0.00%
Number of annual vesting installments \| installment	4
Number of operating segments \| segment	1
Operating lease liabilities	$ 5,533
Operating lease right-of-use assets	$ 4,885	0
Accounting Standards Update 2016-02 \| Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities			$ 6,400
Operating lease right-of-use assets			5,900
Deferred rent credit			$ 500
Janssen Promotion Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Termination of agreement		600
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life	3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life	5 years
Shipping and Handling
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of revenue	$ 2,700	$ 2,100
Revenue Benchmark \| Supplier Concentration Risk \| Two Suppliers
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk percentage	96.00%	96.00%
Revenue Benchmark \| AVISE CTD Test \| Product Concentration Risk
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk percentage	84.00%	81.00%
Blue Shield
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	$ 1,200	$ 1,200

Summary of Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 45,563	$ 48,299
Commercial
Disaggregation of Revenue [Line Items]
Revenue	18,975	27,499
Government
Disaggregation of Revenue [Line Items]
Revenue	17,687	9,221
Client
Disaggregation of Revenue [Line Items]
Revenue	7,928	9,288
Other
Disaggregation of Revenue [Line Items]
Revenue	973	1,091
Blue Shield
Disaggregation of Revenue [Line Items]
Revenue	$ 0	$ 1,200

- 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 https://asc.fasb.org/extlink&oid=126901519&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 https://asc.fasb.org/extlink&oid=126901519&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 https://asc.fasb.org/extlink&oid=126901519&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 https://asc.fasb.org/extlink&oid=126901519&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 https://asc.fasb.org/extlink&oid=126901519&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 https://asc.fasb.org/extlink&oid=126920106&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 https://asc.fasb.org/extlink&oid=126901519&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 https://asc.fasb.org/extlink&oid=126901519&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 https://asc.fasb.org/extlink&oid=126901519&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 https://asc.fasb.org/extlink&oid=126920106&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 https://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, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 62,391	$ 99,442
Restricted cash	200	100
Total cash, cash equivalents and restricted cash	$ 62,591	$ 99,542	$ 57,548

Summary of Significant Accounting Policies - Securities (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Class of Stock [Line Items]
Anti-dilutive securities excluded from computation (in shares)	2,925,262	2,858,956
Warrants to purchase common stock
Class of Stock [Line Items]
Anti-dilutive securities excluded from computation (in shares)	409,108	409,108
Common stock options
Class of Stock [Line Items]
Anti-dilutive securities excluded from computation (in shares)	1,421,235	2,014,330
Restricted stock units
Class of Stock [Line Items]
Anti-dilutive securities excluded from computation (in shares)	1,036,208	415,325
Employee stock purchase plan
Class of Stock [Line Items]
Anti-dilutive securities excluded from computation (in shares)	58,711	20,193

Other Financial Information - Prepaid Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Other Financial Information [Abstract]
Diagnostic testing supplies	$ 1,795	$ 1,091
Prepaid product royalties	40	49
Prepaid maintenance and insurance contracts	2,072	2,008
Other prepaid and other current assets	236	490
Prepaid and other current assets	$ 4,143	$ 3,638

Other Financial Information - Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 13,321	$ 8,656
Less: accumulated depreciation and amortization	(5,124)	(3,884)
Property and equipment, net	8,197	4,772
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	98	83
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	5,136	4,361
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment	1,482	1,206
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	5,223	1,151
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 1,382	$ 1,855

Other Financial Information - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 1,600	$ 900
Long-lived assets impairment	$ 397	0
Impairment, Long-Lived Asset, Held-for-Use, Statement of Income or Comprehensive Income [Extensible Enumeration]	Selling, general and administrative expenses
Goodwill Impairment	$ 5,506	0
Laboratory equipment
Property, Plant and Equipment [Line Items]
Gross book value of assets under finance leases	$ 2,800	$ 2,500

Other Financial Information - Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Roll Forward]
Beginning balance	$ 5,506
Goodwill impairment	(5,506)	$ 0
Ending balance	$ 0	$ 5,506

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References + Details

Other Financial Information - Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Other Financial Information [Abstract]
Accrued payroll and related expenses	$ 2,355	$ 4,048
Accrued interest	142	139
Accrued purchases of goods and services	803	510
Accrued royalties	514	180
Accrued clinical study activity	162	254
Finance lease obligations, current portion	700	587
Refund liability	445	0
Other accrued liabilities	226	1,108
Accrued and other current liabilities	$ 5,347	$ 6,826

Borrowings - Narrative (Details)	1 Months Ended		12 Months Ended
Borrowings - Narrative (Details)	Nov. 30, 2021 USD ($) installment	Sep. 30, 2017 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	May 31, 2022 USD ($)
2017 Term loan \| Loan payable \| Innovatus Life Sciences Lending Fund
Debt Instrument [Line Items]
Term loan borrowings		$ 25,000,000	$ 0
Interest rate (as a percent)	8.00%
Term loan, paid in-kind, interest rate	2.00%
Term loan, effective interest rate	8.50%
Number of monthly installments \| installment	24
Term loan, fee incurred upon payment of final installment			$ 1,000,000
Term loan, prepayment premium percentage	2.00%
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	$ 2,000,000.0
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			$ 600,000	$ 500,000
Equipment Notes Payable
Debt Instrument [Line Items]
Term loan, effective interest rate					5.28%
Notes payable					$ 800,000
Notes payable current					200,000
Notes payable noncurrnet					$ 600,000

Borrowings - Future Minimum Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Disclosure [Abstract]
2023	$ 1,911
2024	3,205
2025	16,377
2026	14,973
Total	36,466
Unamortized debt discount and issuance costs	(158)
Interest	(7,340)
Total borrowings, net of discounts and debt issuance costs	28,968
Borrowings-current portion	(190)	$ 0
Borrowings-non-current portion, net of discounts and debt issuance costs	$ 28,778	$ 27,478

Commitment and Contingencies - Narrative (Details) - USD ($)		1 Months Ended		12 Months Ended
	Aug. 23, 2021	Nov. 30, 2021	May 31, 2021	Dec. 31, 2022	Dec. 31, 2021
Loss Contingencies [Line Items]
Rent expense					$ 900,000
Period for royalties to begin		18 months
Purchase obligation, due in next twelve months					6,000,000.0
Purchase obligation, due in second year					$ 6,900,000
Annual increase in purchase commitments					15.00%
Office and Laboratory
Loss Contingencies [Line Items]
Operating lease, renewal term				5 years
Office
Loss Contingencies [Line Items]
Operating lease, monthly base rent	$ 66,021
Operating lease, annual increase in base rent payment percentage	3.00%
AHN Collaboration
Loss Contingencies [Line Items]
Collaboration agreement, collaboration expenses				$ 400,000
Minimum
Loss Contingencies [Line Items]
Finance lease, term of contract				3 years
Minimum \| Licensing Agreements
Loss Contingencies [Line Items]
Royalty obligation, percent of net sales				1.50%
Maximum
Loss Contingencies [Line Items]
Finance lease, term of contract				5 years
Maximum \| Licensing Agreements
Loss Contingencies [Line Items]
Royalty obligation, percent of net sales				7.00%
Prometheus Laboratories
Loss Contingencies [Line Items]
Future minimum royalty commitment				$ 1,200,000
Advance royalties payment				$ 100,000
Prometheus Laboratories \| Minimum
Loss Contingencies [Line Items]
Royalty obligation, percent of net sales				2.50%
Allegheny Health Network Research Institute
Loss Contingencies [Line Items]
Collaboration fee			$ 400,000
Allegheny Health Network Research Institute \| Licensing Agreements
Loss Contingencies [Line Items]
Initial license fee			$ 400,000
Queen Mary University Of London \| Licensing Agreements
Loss Contingencies [Line Items]
Initial license fee		$ 400,000
One time payment		$ 100,000

Commitment and Contingencies - Lease Balances (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Operating lease right-of-use assets	$ 4,885	$ 0
Finance lease, right-of-use asset, after accumulated amortization	$ 1,427
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Property and equipment, net
Operating lease liabilities	$ 1,040	0
Finance lease obligations, current portion	$ 700	$ 587
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accrued and other current liabilities	Accrued and other current liabilities
Non-current operating lease liabilities	$ 4,493	$ 0
Lease obligations, net of current portion	$ 848
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other non-current liabilities

Commitment and Contingencies - Costs Associated with the Company's Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 1,540
Amortization of lease assets	679
Interest on finance lease liabilities	80
Total lease cost	2,299
Variable lease cost	$ 165

Commitment and Contingencies - Supplemental Cash Flow Information On Leases And Weighted-Average Lease Term (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash paid for amounts included in the measurement of lease liabilities
Operating cash out flows from operating leases	$ 1,262
Operating cash out flows from interest paid on finance leases	80
Financing cash out flows from finance leases	$ 667	$ 525
Weighted-average remaining lease term (years)
Operating leases	4 years 3 months 18 days
Finance leases	1 year 11 months 8 days
Weighted-average discount rate
Operating leases	8.00%
Finance leases	4.80%

Commitment and Contingencies - Future Payments Under Operating And Finance Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Operating Leases
2023	$ 1,446
2024	1,489
2025	1,533
2026	1,584
Thereafter	539
Total minimum lease payments	6,591
Less: imputed interest	(1,058)
Total lease liabilities	5,533
Less: current portion	(1,040)	$ 0
Lease obligations, net of current portion	4,493	0
Finance Leases
2023	828
2024	574
2025	248
2026	147
Thereafter	29
Total minimum lease payments	1,826
Less: imputed interest	(278)
Total lease liabilities	1,548
Less: current portion	(700)	$ (587)
Lease obligations, net of current portion	$ 848

Commitment and Contingencies - Minimum Annual Lease Payments Under Non-cancelable Lease Arrangements (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2022	$ 1,337
2023	1,445
2024	1,489
2025	1,533
2026	1,584
Thereafter	539
Total minimum lease payments	$ 7,927

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total borrowings, net of discounts and debt issuance costs	$ 28,968
Recurring
Assets:
Total	59,538
Recurring \| Money market funds, included in cash and cash equivalents
Assets:
Cash and cash equivalents, fair value disclosure	29,438	$ 95,761
Recurring \| Certificate of deposit, included in cash and cash equivalents
Assets:
Cash and cash equivalents, fair value disclosure	30,100
Recurring \| Level 1
Assets:
Total	59,538
Recurring \| Level 1 \| Money market funds, included in cash and cash equivalents
Assets:
Cash and cash equivalents, fair value disclosure	29,438	95,761
Recurring \| Level 1 \| Certificate of deposit, included in cash and cash equivalents
Assets:
Cash and cash equivalents, fair value disclosure	30,100
Recurring \| Level 2
Assets:
Total	0
Recurring \| Level 2 \| 2017 Term loan
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total borrowings, net of discounts and debt issuance costs	28,300
Debt Instrument, Fair Value Disclosure	26,900
Recurring \| Level 2 \| Money market funds, included in cash and cash equivalents
Assets:
Cash and cash equivalents, fair value disclosure	0	0
Recurring \| Level 2 \| Certificate of deposit, included in cash and cash equivalents
Assets:
Cash and cash equivalents, fair value disclosure	0
Recurring \| Level 3
Assets:
Total	0
Recurring \| Level 3 \| Money market funds, included in cash and cash equivalents
Assets:
Cash and cash equivalents, fair value disclosure	0	$ 0
Recurring \| Level 3 \| Certificate of deposit, included in cash and cash equivalents
Assets:
Cash and cash equivalents, fair value disclosure	$ 0

Stockholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands					12 Months Ended
	Sep. 15, 2022	Jun. 22, 2021	Mar. 25, 2021	Nov. 10, 2020	Dec. 31, 2022	Dec. 31, 2021
Class of Stock [Line Items]
Estimated offering expenses for aggregate expenses						$ 4,435
Exercise of common stock warrants (in shares)					0
Cowen Equity Distribution Agreement
Class of Stock [Line Items]
Proceeds from public offering, net	$ 50,000
Exchanging Stockholders
Class of Stock [Line Items]
Number of shares exchanged for warrants (in shares)		804,951
Class of warrant or right, exercise price of warrants or rights (in dollars per share)		$ 0.001
Sale of stock, percentage of ownership after transaction		4.99%
Number of warrants exercised (in shares)					0
Common Stock
Class of Stock [Line Items]
Sale of stock, number shares issued (in shares)			4,255,000	150,000,000.0
Shares issued in public offering, price per share (in dollars per share)			$ 16.25
Proceeds from public offering, net			$ 64,700
Estimated offering expenses for aggregate expenses			$ 4,400
Exercise of common stock warrants (in shares)						17,719

Stockholders' Equity - Warrants to Purchase Common Stock Outstanding (Details)	Dec. 31, 2022 $ / shares shares
Class of Stock [Line Items]
Warrants issued to purchase redeemable convertible preferred stock (in shares)	1,214,059
Warrant expiration January 19, 2026
Class of Stock [Line Items]
Warrants issued to purchase redeemable convertible preferred stock (in shares)	237,169
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 (in shares)	67,086
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 (in shares)	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 (in shares)	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 (in shares)	20,944
Class of warrant or right, exercise price of warrants or rights (in dollars per share) \| $ / shares	$ 14.32
No expiration
Class of Stock [Line Items]
Warrants issued to purchase redeemable convertible preferred stock (in shares)	804,951
Class of warrant or right, exercise price of warrants or rights (in dollars per share) \| $ / shares	$ 0.001

Stock Option Plan - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2023
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)	$ 2.74	$ 8.83
Common stock, fair value per share (in dollars per share)	$ 2.40	$ 11.63
Intrinsic value of options exercised	$ 600	$ 100
Stock options, unrecognized compensation cost	$ 1,800
Stock options, cost not yet recognized, remaining weighted average vesting period	1 year 1 month 6 days
Stock-based compensation expense	$ 4,704	4,728
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual percentage increase in shares available for issuance under the Plan	1.00%
Maximum Employee payroll deduction percentage	20.00%
Stock options, cost not yet recognized, remaining weighted average vesting period	2 months 12 days
Stock-based compensation expense	$ 100	$ 200
Unrecognized compensation cost related to stock purchase	$ 100
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)			165,500
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, fair value per share (in dollars per share)	$ 7.28	$ 16.54
Grant date fair value of RSUs vested	$ 700
Vested (in shares)		0
Awards granted (in dollars per share)	$ 5.89	$ 16.53
Stock options, unrecognized compensation cost	$ 6,000
Stock options, cost not yet recognized, remaining weighted average vesting period	3 years 3 months 18 days
2019 Incentive Award Plan \| 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
Annual percentage increase in shares available for issuance under the Plan	4.00%
Shares that remain available for future awards	1,452,435
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)			661,999

Stock Option Plan - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Number of Options
Outstanding, Beginning balance (in shares)	2,014,330
Granted (in shares)	63,000
Exercised (in shares)	(245,186)
Forfeited (in shares)	(257,982)
Expired (in shares)	(152,927)
Outstanding, Ending balance (in shares)	1,421,235	2,014,330
Vested and expected to vest (in shares)	1,421,235
Options exercisable (in Shares)	1,129,333
Weighted- Average Exercise Price
Outstanding, Beginning balance (in dollars per share)	$ 12.10
Granted (in dollars per share)	5.25
Exercised (in dollars per share)	0.26
Forfeited (in dollars per share)	16.09
Expired (in dollars per share)	13.73
Outstanding, Ending balance (in dollars per share)	12.94	$ 12.10
Vested and expected to vest (in dollars per share)	12.94
Options exercisable (in dollars per share)	$ 12.94
Weighted-Average Remaining Contractual Term (Years) and Aggregate Instrinsic Value
Outstanding, Weighted Average Remaining Contractual Term	7 years 1 month 2 days	7 years 10 months 13 days
Vested and expected to vest, Weighted Average Remaining Contractual Term	7 years 1 month 2 days
Options exercisable, Weighted Average Remaining Contractual Term	6 years 10 months 20 days
Outstanding, Aggregate Intrinsic Value	$ 483	$ 5,428
Vested and Expected to Vest, Aggregate Intrinsic Value	483
Options Exercisable, Aggregate Intrinsic Value	$ 483

Stock Option Plan - Restricted Stock Units (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Weighted- Average Grant Date Fair Value
Outstanding, Beginning balance (in dollars per share)	$ 11.63
Outstanding, Ending balance (in dollars per share)	$ 2.40	$ 11.63
Restricted stock units
Number of Shares
Outstanding, Beginning balance (in shares)	415,325
Awards granted (in shares)	1,076,725
Awards released (in shares)	(100,586)
Awards canceled (in shares)	(355,256)
Outstanding, Ending balance (in shares)	1,036,208	415,325
Weighted- Average Grant Date Fair Value
Outstanding, Beginning balance (in dollars per share)	$ 16.54
Awards granted (in dollars per share)	5.89	$ 16.53
Awards released (in dollars per share)	16.55
Awards canceled (in dollars per share)	11.29
Outstanding, Ending balance (in dollars per share)	$ 7.28	$ 16.54
Aggregate Intrinsic Value
Outstanding, Aggregate Intrinsic Value	$ 2,487	$ 4,830

Stock Option Plan - Fair Value Assumptions (Details)	12 Months Ended
Stock Option Plan - Fair Value Assumptions (Details)	Dec. 31, 2022	Dec. 31, 2021
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	54.00%	56.00%
Expected volatility rate, maximum		60.00%
Risk-free interest rate, minimum	3.40%	0.80%
Risk-free interest rate, maximum		1.10%
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 6 months
Stock options \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)		6 years 1 month 6 days
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility rate, minimum	45.00%	45.00%
Expected volatility rate, maximum	57.00%	60.00%
Risk-free interest rate, minimum	0.60%	0.10%
Risk-free interest rate, maximum	3.30%
Dividend yield	0.00%	0.00%
Expected term (in years)	6 months	6 months

Stock Option Plan - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 4,704	$ 4,728
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	213	164
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	3,860	3,943
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 631	$ 621

Stock Option Plan - Common Stock Reserved For Future Issuance (Details)	Dec. 31, 2022 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	5,537,524
Warrants to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	1,214,059
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)	1,421,235
Common stock reserved for issuance upon vesting of outstanding restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	1,036,370
Common shares available for grant under the 2019 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	1,452,435
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)	413,425

Income Taxes - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Current:
Federal	$ 0	$ 0
State	24	27
Total current	24	27
Deferred:
Federal	(137)	137
State	(169)	11
Total deferred	(306)	148
Provision (benefit) for income tax	$ (282)	$ 175

- 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, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Federal statutory tax rate	(21.00%)	(21.00%)
State income taxes, net of federal tax benefits	(4.30%)	(3.80%)
Research and development tax credits	(1.50%)	(1.20%)
Stock compensation	1.40%	0.90%
Non-deductible expenses	0.90%	1.10%
Change in valuation allowance	23.90%	24.60%
Effective tax rate	(0.60%)	0.60%

Income Taxes - Reconciliation of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Net operating loss carryforwards	$ 29,789	$ 22,365
Research and development tax credits	2,216	1,102
Accruals, reserves and other	349	1,055
Interest expense	2,236	1,953
Indefinite lived assets	362	0
Stock compensation	1,606	1,407
Lease liability	1,374	0
Capitalization of research and experimentation costs	2,047	0
Total gross deferred tax assets	39,979	27,882
Less: valuation allowance	(38,567)	(27,158)	$ (20,596)
Deferred tax assets, net	1,412	724
Deferred tax liabilities:
Financing and acquisition-related liabilities	0	(335)
Indefinite lived assets	0	(521)
Right of use assets	(1,206)	0
Basis differences in fixed and intangible assets	(206)	(175)
Deferred tax liabilities, net	(1,412)	(1,031)
Net deferred tax liabilities	$ 0	$ (307)

Income Taxes - Change In Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Changes In The Valuation Allowance For Deferred Tax Assets [Roll Forward]
Valuation allowance at the beginning of the year	$ 27,158	$ 20,596
Increases recorded to income tax provision	11,409	6,562
Valuation allowance at the end of the year	$ 38,567	$ 27,158

Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Federal net operating loss carryforwards	$ 118,400,000	$ 89,400,000
State net operating loss carryforwards	87,000,000.0	61,000,000.0
Federal tax loss carryforwards, subject to expiration	43,500,000
Federal net operating loss carryforwards, carryforward indefinitely	74,900,000
Unrecognized tax benefits	$ 0	$ 0

401(k) Plan (Details) - USD ($) $ in Millions	12 Months Ended
401(k) Plan (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Qualified employee compensation, employer matching contribution, percent of employees' gross pay	4.00%	3.00%
Qualified employee compensation contribution, amount	$ 0.9	$ 0.5