0001274737-23-000088 | 10-Q | XBRL Viewer

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Other Financial Information - Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Other Financial Information [Abstract]
Accrued payroll and related expenses	$ 3,284	$ 2,355
Accrued interest	130	142
Accrued purchases of goods and services	435	803
Accrued royalties	62	514
Accrued clinical study activity	121	162
Finance lease obligations, current portion	595	700
Legal accrual	700	0
Refund liability	254	445
Other accrued liabilities	352	226
Accrued and other current liabilities	$ 5,933	$ 5,347

Stock Option Plan

6 Months Ended

Jun. 30, 2023

Share-Based Payment Arrangement [Abstract]

Stock Option Plan

2019 Incentive Award Plan

In September 2019, the 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 June 30, 2023, 1,740,628 shares of common stock remained available for future awards 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 June 30, 2023, 508,608 shares of common stock remained available for issuance 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 (in thousands)
Outstanding, December 31, 2022	1,421,235	$	12.94	7.09	$	483
Granted	58,500	$	3.15
Exercised	(93,335)	$	0.26
Forfeited	(32,426)	$	14.38
Expired	(359,448)	$	17.02
Outstanding, June 30, 2023	994,526	$	12.03	6.90	$	349
Vested and expected to vest, June 30, 2023	994,526	$	12.03	6.90	$	349
Options exercisable, June 30, 2023	825,513	$	12.24	6.66	$	349

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 aggregate intrinsic value of options exercised during the six months ended June 30, 2023 was $0.2 million. There were no options exercised during the six months ended June 30, 2022. As of June 30, 2023, total unrecognized compensation cost related to option awards was $0.9 million, which is expected to be recognized over a remaining weighted-average vesting period of 0.91 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 (in thousands)
Outstanding, December 31, 2022	1,036,208	$	7.28	$	2,487
Awards granted	796,400	$	2.42
Awards released	(144,985)	$	12.01
Awards canceled	(89,045)	$	9.53
Outstanding, June 30, 2023	1,598,578	$	4.30	$	4,636

As of June 30, 2023, all of the outstanding restricted stock units were unvested. The fair value of restricted stock units vested in the six months ended June 30, 2023 and 2022 was $0.4 million and $0.6 million, respectively. The weighted average grant date fair value for restricted stock units granted in the six months ended June 30, 2023 and 2022 was $2.42 and $8.66, respectively. As of June 30, 2023, 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

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 condensed statements of operations is as follows (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Costs of revenue	$	63	$	59	$	116	$	103
Selling, general and administrative	874		1,203		1,705		2,321
Research and development	41		178		143		392
Total	$	978	$	1,440	$	1,964	$	2,816

Organization	6 Months Ended
Organization	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Description of Business Exagen Inc. (the Company) is a commercial-stage diagnostics company which exists to provide clarity in autoimmune disease decision making with the goal of improving patients' clinical outcomes. 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. As of June 30, 2023, the Company had cash and cash equivalents of $31.5 million and had an accumulated deficit of $268.2 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 condensed 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.

Borrowings - Narrative (Details)		1 Months Ended		3 Months Ended		6 Months Ended
Borrowings - Narrative (Details)	Apr. 28, 2023 USD ($)	Nov. 30, 2021 USD ($) installment	Sep. 30, 2017 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)
2017 Term loan \| Innovatus Life Sciences Lending Fund \| Loan payable
Debt Instrument [Line Items]
Term loan borrowings			$ 25,000,000
Remaining borrowing capacity				$ 0		$ 0
Term loan, interest rate	2.00%
Term loan, paid in-kind, interest rate	1.50%
Term loan, effective interest rate	10.80%
Number of monthly installments \| installment		10
Term loan, fee incurred upon payment of final installment				$ 1,000,000		$ 1,000,000
Term loan, prepayment premium percentage		2.00%
Term loan, annual reduction in prepayment penalty percentage		1.00%
Prepayment of principal	$ 10,000,000
Term loan, covenant, revenue performance period						12 months
Debt instrument, minimum cash balance						50.00%
Term loan, covenant, number of days to cure covenant if performance measure is not met						30 days
Term loan covenant, minimum unrestricted cash balance		$ 2,000,000.0
Term loan covenant, increase to interest rate				4.00%		4.00%
2017 Term loan \| Innovatus Life Sciences Lending Fund \| Loan payable \| Prime Rate
Debt Instrument [Line Items]
Variable rate	8.00%
2017 Term loan \| Innovatus Life Sciences Lending Fund \| Paid in-kind note
Debt Instrument [Line Items]
Term loan, paid in-kind loans issued				$ 100,000	$ 100,000	$ 200,000	$ 300,000
Equipment Notes Payable
Debt Instrument [Line Items]
Term loan, effective interest rate				5.28%		5.28%
Notes payable				$ 1,000,000		$ 1,000,000
Notes payable, current				300,000		300,000
Notes payable, noncurrent				$ 700,000		$ 700,000

Stockholders' Equity - Schedule of Outstanding Warrants (Details)	Jun. 30, 2023 $ / 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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2023

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
	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Medicare	29	%	15	%	34	%	18	%
Medicare Advantage	19	%	23	%	18	%	19	%
Blue Shield	10	%	*		*		*
Aetna	*		10	%	*		*



*						Less than 10%.


	Accounts Receivable, Net
	June 30, 2023		December 31, 2022
Medicare	49	%	21	%
Medicare Advantage	14	%	13	%

Schedule of Disaggregation of Revenue

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


	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Revenue:
Commercial	$	7,484	$	4,510	$	11,699	$	10,933
Government	4,189		1,139		8,615		3,259
Client(1)	2,273		1,755		4,680		3,346
Other(2)	191		202		373		462
Total revenue	$	14,137	$	7,606	$	25,367	$	18,000

(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):


	June 30, 2023		December 31, 2022
Cash and cash equivalents	$	31,466	$	62,391
Restricted cash	200		200
	$	31,666	$	62,591

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):


	June 30, 2023		December 31, 2022
Cash and cash equivalents	$	31,466	$	62,391
Restricted cash	200		200
	$	31,666	$	62,591

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):


	June 30, 2023	June 30, 2022
Warrants to purchase common stock	409,108	409,108
Common stock options	994,526	1,949,374
Restricted stock units	1,598,578	784,940
Employee stock purchase plan	60,719	30,303
Total	3,062,931	3,173,725

Organization (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 31,466	$ 62,391
Accumulated deficit	$ (268,228)	$ (255,527)

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Commitment and Contingencies	6 Months Ended
Commitment and Contingencies	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies 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 has ongoing royalty payment obligations 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 condensed statements of operations. Collaboration Obligations In May 2021, the Company entered into a master research collaboration agreement with Allegheny Health Network Research Institute (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 $0.1 million for each of the three months ended June 30, 2023 and 2022. For each of the six months ended June 30, 2023 and 2022, collaboration expenses were $0.2 million. Collaboration expenses under the AHN collaboration are included in research and development expenses. Supply Agreements In December 2021, the Company entered into an amended supply agreement with one supplier for reagents which includes minimum annual purchase commitments of $6.9 million, $8.0 million and $9.2 million for the years ending December 31, 2023, 2024 and 2025, respectively. 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. In February 2022, the Company received a subpoena issued by the U.S. Department of Justice (DOJ) requesting documents related to an investigation of potential federal regulatory healthcare offenses. The Company has fully cooperated with the DOJ in connection with the investigation. The DOJ revealed that there is a suit under seal in the Commonwealth of Massachusetts. The suit will remain under seal until a definitive settlement agreement is executed. In July 2023, the Company reached an agreement in principle with the DOJ to resolve this matter and recorded a charge of $0.7 million for the three and six months ended June 30, 2023 as a result. This amount is included in selling, general and administrative expenses. There can be no assurance that a definitive agreement will be executed or that the material terms of the definitive agreement will remain the same as the agreement in principle.

Borrowings

6 Months Ended

Jun. 30, 2023

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 (the Amended Loan Agreement), pursuant to which the Company borrowed $25.0 million. As of June 30, 2023, no additional amounts remained available to borrow under the 2017 Term Loan.

On April 28, 2023, the Company entered into the Third Loan Amendment to the 2017 Term Loan (the Third Loan Amendment). The Third Loan Amendment was treated as a modification. Pursuant to the Third Loan Amendment, the interest rate on all borrowings under the Amended Loan Agreement is the sum (the Basic Rate) of (a) the greater of 8.0% or The Wall Street Journal prime rate (the Prime Rate), plus (b) 2.0%. Under the Amended Loan Agreement, an amount equal to 1.5% of the Basic Rate will be payable in-kind and capitalized to the principal amount of the outstanding term loan on a monthly basis until April 1, 2026, after which interest is scheduled to accrue at the Basic Rate. The maturity date of the loan was extended to December 31, 2026. As of June 30, 2023, the Company estimated the effective interest rate of this loan to be approximately 10.8%. Accrued interest is due and payable monthly, unless the Company elects to pay paid-in-kind interest. The outstanding principal and accrued interest under the Amended Loan Agreement is to be repaid in ten equal monthly installments commencing in April 2026. Upon repayment of the final installment under the Amended Loan Agreement, 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 the loan using the effective interest method. For each of the three months ended June 30, 2023 and 2022, the Company issued PIK Loans totaling $0.1 million. For the six months ended June 30, 2023 and 2022, the Company issued PIK Loans totaling $0.2 million and $0.3 million, respectively.

The Amended Loan Agreement requires a prepayment premium of 2% of the aggregate outstanding principal and decreases by 1% on each of November 1, 2023 and 2024. However, this fee was waived on April 28, 2023, at which time the Company prepaid $10.0 million of principal (the Term Loan Prepayment).

The Amended Loan Agreement is collateralized by a first priority security interest in substantially all of the Company's assets, including intellectual property. The affirmative covenants of the Amended Loan Agreement 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, however the Company is not required to comply with the revenue covenant for any quarter during which it maintains a minimum aggregate cash balance equal to fifty percent of the aggregate principal amount of the 2017 Term Loan (excluding any capitalized interest paid-in-kind) at all times during such quarter. The consequences of failing to achieve the performance covenants, when applicable, will be cured if, (i) within thirty days of failing to achieve the performance covenant, the Company submits a new Board approved financial plan to Innovatus under which the Company is expected to break even on a cash flow basis prior to the maturity date, and (ii) within thirty days of the submission of such financial plan, the Company issues additional equity securities or subordinated debt with net proceeds sufficient to fund any cash flow deficiency generated from operations, as defined in the Amended Loan Agreement. The Amended Loan Agreement 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 Amended Loan 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.

As of June 30, 2023, the Company was in compliance with all covenants of the Amended Loan Agreement.

Upon an event of default in any of the Amended Loan Agreement covenants, the repayment of the 2017 Term Loan may be accelerated, and the applicable interest rate will be increased by 4.0% until the default is cured. Although repayment of the 2017 Term Loan can be accelerated under certain circumstances, the Company believes acceleration of this loan is not probable as of the date of these condensed financial statements. Accordingly, the Company has reflected the amounts of the Third 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 June 30, 2023, the total notes payable balance related to this financed equipment was $1.0 million, with $0.3 million classified within borrowings-current portion and $0.7 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 June 30, 2023, future minimum aggregate payments, including interest, for outstanding borrowings are as follows (in thousands):


2023 (remaining)	$	950
2024	1,908
2025	1,928
2026	21,215
Total	26,001
Less:
Unamortized debt discount and issuance costs	(134)
Interest	(6,457)
Total borrowings, net of discounts and debt issuance costs	19,410
Less: Borrowings-current portion	(257)
Borrowings-non-current portion, net of discounts and debt issuance costs	$	19,153

- 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://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 470
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//470/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1E
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

+ Details

Other Financial Information - Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 14,038	$ 13,321
Less: accumulated depreciation and amortization	(6,163)	(5,124)
Property and equipment, net	7,875	8,197
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	98	98
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	6,458	5,136
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment	1,557	1,482
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	5,284	5,223
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 641	$ 1,382

Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation and Use of Estimates

The accompanying interim condensed balance sheet as of June 30, 2023, condensed statements of operations and stockholders' equity for the three and six months ended June 30, 2023, cash flows for the six months ended June 30, 2023 and the related footnote disclosures are unaudited and have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (SEC), and with accounting principles generally accepted in the United States (GAAP) applicable to interim financial statements. These unaudited condensed financial statements and related footnote disclosures should be read in conjunction with the Company’s audited financial statements for the fiscal year ended December 31, 2022, included in its Annual Report on Form 10-K filed with the SEC on March 20, 2023. In management's opinion, the unaudited interim condensed financial statements have been prepared on the same basis as the audited financial statements and include all normal adjustments, necessary for the fair presentation of the Company's financial position as of June 30, 2023 and its results of operations for the periods presented. The results for the three and six months ended June 30, 2023 are not necessarily indicative of the results expected for the full fiscal year or any other interim period. The year-end condensed balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP.

The preparation of the accompanying condensed 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 condensed 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 condensed financial statements include, but are not limited to revenue recognition, the recoverability of its long-lived assets and net deferred tax assets (and related valuation allowance). 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. The Company has not experienced any losses on its 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
	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Medicare	29	%	15	%	34	%	18	%
Medicare Advantage	19	%	23	%	18	%	19	%
Blue Shield	10	%	*		*		*
Aetna	*		10	%	*		*



*						Less than 10%.


	Accounts Receivable, Net
	June 30, 2023		December 31, 2022
Medicare	49	%	21	%
Medicare Advantage	14	%	13	%

For the three months ended June 30, 2023 and 2022, approximately 88% and 77%, respectively, of the Company's revenue was related to the AVISE® CTD test. Revenue related to the AVISE® CTD test for the six months ended June 30, 2023 and 2022 was approximately 88% and 81%, respectively.

The Company is dependent on key suppliers for certain laboratory materials. For the three months ended June 30, 2023 and 2022, approximately 95% and 97%, respectively, of the Company's diagnostic testing supplies were purchased from two suppliers. For each of the six months ended June 30, 2023 and 2022, 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):


	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Revenue:
Commercial	$	7,484	$	4,510	$	11,699	$	10,933
Government	4,189		1,139		8,615		3,259
Client(1)	2,273		1,755		4,680		3,346
Other(2)	191		202		373		462
Total revenue	$	14,137	$	7,606	$	25,367	$	18,000

(1)Includes hospitals, other laboratories, etc.

(2)Includes patient self-pay.

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 value of the Company's long-term borrowings is determined by Level 2 inputs and based primarily on quoted market prices for the same or similar issues. As of June 30, 2023, the 2017 Term Loan (as defined below) had a carrying value of $18.5 million and a fair value of $19.1 million. 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 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 other long-term borrowing was $0.9 million and approximated its fair value as of June 30, 2023. As of December 31, 2022, the recorded value of the Company's other long term borrowing was $0.8 million and approximated its fair value.

Cash, Cash Equivalents and Restricted Cash

The Company considers all highly-liquid investments purchased with a remaining maturity date of three months or less upon acquisition to be cash equivalents. These investments 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 in the amount of $0.2 million as collateral for the balances borrowed on these cards. The Company has classified the value of this certificate of deposit (including all interest earned thereon) within other assets in the accompanying balance sheets. The Company has the right to terminate the credit card program at any time. Upon termination of the credit card program and repayment of all outstanding balances owed, the Company may redeem the certificate of deposit (and all interest earned thereon).

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


	June 30, 2023		December 31, 2022
Cash and cash equivalents	$	31,466	$	62,391
Restricted cash	200		200
	$	31,666	$	62,591

Long-lived Assets

The Company’s long-lived assets are comprised principally of its property and equipment and operating lease assets. The Company amortizes 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, into groupings, a determination which we principally make on the basis of whether the assets are specific to a particular test we offer or technology we are developing. If the Company identifies a change in the circumstances related to its long-lived assets that indicates the carrying value of any such asset may not be recoverable, the Company will perform an impairment analysis. A

long-lived asset 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.

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. Adjustments are recorded 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 three months ended June 30, 2023 and 2022 was a $1.5 million net revenue increase and a $1.2 million net revenue decrease, respectively, associated with changes in estimated variable consideration related to performance obligations satisfied in previous periods. Included in revenues for the six months ended June 30, 2023 and 2022 was a $1.8 million net revenue increase and a $1.6 million net revenue decrease, 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.

Accounts Receivable and Allowance for Credit Losses

We accrue an allowance for credit losses against our accounts receivable based on management’s current estimate of amounts that will not be collected. Management’s estimates are typically based on historical loss information adjusted for current conditions. We generally do not perform evaluations of the financial condition of our customers and generally do not require collateral. The allowance for credit losses was zero as of June 30, 2023. Adjustments for implicit price concessions attributable to variable consideration, as discussed above, are incorporated into the measurement of the accounts receivable balances and are not part of the allowance for credit losses.

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 $0.4 million and $0.6 million for the three months ended June 30, 2023 and 2022, respectively. For the six months ended June 30, 2023 and 2022, total advertising and marketing costs were approximately $0.7 million and $0.9 million, respectively. These costs are included in selling, general and administrative expenses in the accompanying condensed statements of operations.

Shipping and Handling Costs

Costs incurred for shipping and handling are included in costs of revenue in the accompanying condensed statements of operations and totaled approximately $0.6 million and $0.7 million for the three months ended June 30, 2023 and 2022, respectively. For each of the six months ended June 30, 2023 and 2022, shipping and handling costs were approximately $1.3 million.

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.

Net Loss Per Share

Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. 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, stock options, 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 three and six months ended June 30, 2023 and 2022,

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):


	June 30, 2023	June 30, 2022
Warrants to purchase common stock	409,108	409,108
Common stock options	994,526	1,949,374
Restricted stock units	1,598,578	784,940
Employee stock purchase plan	60,719	30,303
Total	3,062,931	3,173,725

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 June 2016, the FASB issued Accounting Standards Update (ASU) 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires the measurement of expected credit losses (based on historical experience, current conditions and reasonable forecasts) for financial instruments (such as accounts receivable) held at the reporting date which are carried at amortized cost. 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 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. The adoption did not have an impact on its condensed financial statements.

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). ASU 2020-06 eliminates the beneficial conversion and cash conversion accounting models for convertible instruments. It also amends the accounting for certain contracts in an entity’s own equity that are currently accounted for as derivatives because of specific settlement provisions. In addition, ASU 2020-06 modifies how particular convertible instruments and certain contracts that may be settled in cash or shares impact the diluted EPS computation. The amendments in ASU 2020-06 are effective for smaller reporting companies as defined by the SEC for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. The Company early adopted ASU 2020-06 as of January 1, 2023. The adoption did not have an impact on its condensed financial statements.

Unaudited Condensed Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Cash flows from operating activities:
Net loss	$ (12,701)	$ (24,937)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,056	597
Amortization of debt discount and debt issuance costs	80	78
Non-cash interest expense	226	272
Loss on disposal of assets	129	0
Non-cash lease expense	473	514
Stock-based compensation	1,964	2,816
Changes in assets and liabilities:
Accounts receivable, net	(10,158)	939
Prepaid expenses and other current assets	573	576
Other assets	(101)	(201)
Operating lease liabilities	(506)	(382)
Accounts payable	(1,750)	751
Accrued and other current liabilities	812	(751)
Net cash used in operating activities	(19,903)	(19,728)
Cash flows from investing activities:
Purchases of property and equipment	(720)	(3,033)
Proceeds from disposal of property and equipment	2	0
Net cash used in investing activities	(718)	(3,033)
Cash flows from financing activities:
Proceeds from exercise of stock options	27	0
Payments of taxes withheld on vested restricted stock units	0	(222)
Proceeds from common stock issued under Employee Stock Purchase Plan	152	231
Principal payments on finance lease obligations	(369)	(303)
Principal payment on note payable obligations	(114)	0
Principal payment on long-term debt	(10,000)	0
Net cash used in financing activities	(10,304)	(294)
Net change in cash, cash equivalents and restricted cash	(30,925)	(23,055)
Cash, cash equivalents and restricted cash, beginning of period	62,591	99,542
Cash, cash equivalents and restricted cash, end of period	31,666	76,487
Supplemental disclosure of cash flow information:
Cash paid for interest	898	860
Supplemental disclosure of non-cash items:
Equipment purchased under finance lease obligations	0	293
Equipment purchased under notes payable obligations	250	0
Costs incurred, but not paid, in connection with capital expenditures	$ 61	$ 391

Borrowings (Tables)

6 Months Ended

Jun. 30, 2023

Debt Disclosure [Abstract]

Schedule of Future Minimum Aggregate Payments for Outstanding Borrowings

As of June 30, 2023, future minimum aggregate payments, including interest, for outstanding borrowings are as follows (in thousands):


2023 (remaining)	$	950
2024	1,908
2025	1,928
2026	21,215
Total	26,001
Less:
Unamortized debt discount and issuance costs	(134)
Interest	(6,457)
Total borrowings, net of discounts and debt issuance costs	19,410
Less: Borrowings-current portion	(257)
Borrowings-non-current portion, net of discounts and debt issuance costs	$	19,153

Stock Option Plan - Restricted Stock Units (Details) - Restricted stock units - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding, beginning of period (in shares)	1,036,208
Awards granted (in shares)	796,400
Awards released (in shares)	(144,985)
Awards canceled (in shares)	(89,045)
Outstanding, end of period (in shares)	1,598,578
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding, beginning of period (in dollars per share)	$ 7.28
Awards granted, Weighted-Average Grant Date Fair Value (in dollars per share)	2.42	$ 8.66
Awards released, Weighted-Average Grant Date Fair Value (in dollars per share)	12.01
Awards canceled, Weighted-Average Grant Date Fair Value (in dollars per share)	9.53
Outstanding, end of period (in dollars per share)	$ 4.30
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value [Abstract]
Outstanding, Aggregate Intrinsic Value	$ 4,636		$ 2,487

Summary of Significant Accounting Policies - Revenue by Major Payers (Details) - Customer Concentration Risk	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Medicare \| Revenue
Disaggregation of Revenue [Line Items]
Percent of total revenue	29.00%	15.00%	34.00%	18.00%
Medicare \| Accounts Receivable
Disaggregation of Revenue [Line Items]
Percent of total revenue			49.00%		21.00%
Medicare Advantage \| Revenue
Disaggregation of Revenue [Line Items]
Percent of total revenue	19.00%	23.00%	18.00%	19.00%
Medicare Advantage \| Accounts Receivable
Disaggregation of Revenue [Line Items]
Percent of total revenue			14.00%		13.00%
Blue Shield \| Revenue
Disaggregation of Revenue [Line Items]
Percent of total revenue	10.00%
Aetna \| Revenue
Disaggregation of Revenue [Line Items]
Percent of total revenue		10.00%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Fair Value Measurements

6 Months Ended

Jun. 30, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurements

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. Techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs.

The three-levels of the valuation hierarchy for disclosure of fair value measurements are defined 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):


	June 30, 2023
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds, included in cash and cash equivalents	$	4,082	$	4,082	$	—	$	—
Certificate of deposit, included in cash and cash equivalents	24,000		24,000		—		—
Total	$	28,082	$	28,082	$	—	$	—


	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	$	—	$	—

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

Unaudited Condensed Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Statement [Abstract]
Revenue	$ 14,137	$ 7,606	$ 25,367	$ 18,000
Operating expenses:
Costs of revenue	5,836	6,078	11,762	11,895
Selling, general and administrative expenses	11,953	12,903	23,837	25,055
Research and development expenses	1,263	2,689	2,389	4,793
Total operating expenses	19,052	21,670	37,988	41,743
Loss from operations	(4,915)	(14,064)	(12,621)	(23,743)
Interest expense	(574)	(606)	(1,212)	(1,204)
Other income, net	476	5	1,132	10
Net loss	$ (5,013)	$ (14,665)	$ (12,701)	$ (24,937)
Net loss per share, basic (in dollars per share)	$ (0.28)	$ (0.86)	$ (0.72)	$ (1.46)
Net loss per share, diluted (in dollars per share)	$ (0.28)	$ (0.86)	$ (0.72)	$ (1.46)
Weighted-average number of shares used to compute net loss per share, basic (in shares)	17,655,483	17,058,516	17,591,478	17,025,636
Weighted-average number of shares used to compute net loss per share, diluted (in shares)	17,655,483	17,058,516	17,591,478	17,025,636

Stock Option Plan - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 978	$ 1,440	$ 1,964	$ 2,816
Costs of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	63	59	116	103
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	874	1,203	1,705	2,321
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 41	$ 178	$ 143	$ 392

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 2
-Subparagraph (a)(3)
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
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Reference 21: http://www.xbrl.org/2003/role/disclosureRef
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Reference 22: http://www.xbrl.org/2003/role/disclosureRef
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(v)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

+ Details

Summary of Significant Accounting Policies - Narrative (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) segment	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
New Accounting Pronouncement, Early Adoption [Line Items]
Long-term debt	$ 19,410,000		$ 19,410,000
Restricted cash	200,000		200,000		$ 200,000
Revenue recognized in previous periods	1,500,000	$ (1,200,000)	1,800,000	$ (1,600,000)
Advertising expense	400,000	600,000	$ 700,000	900,000
Number of operating segments \| segment			1
Other Long Term Debt
New Accounting Pronouncement, Early Adoption [Line Items]
Debt instrument	900,000		$ 900,000		800,000
Restricted stock units
New Accounting Pronouncement, Early Adoption [Line Items]
Stock options, vesting period			4 years
2017 Term loan \| Level 2 \| Recurring
New Accounting Pronouncement, Early Adoption [Line Items]
Long-term debt	18,500,000		$ 18,500,000		28,300,000
Debt instrument	19,100,000		19,100,000		$ 26,900,000
Shipping and Handling
New Accounting Pronouncement, Early Adoption [Line Items]
Cost of revenue	$ 600,000	$ 700,000	$ 1,300,000	$ 1,300,000
Revenue \| Product Concentration Risk \| AVISE CTD Test
New Accounting Pronouncement, Early Adoption [Line Items]
Percent of total revenue	88.00%	77.00%	88.00%	81.00%
Revenue \| Supplier Concentration Risk \| Two Major Suppliers
New Accounting Pronouncement, Early Adoption [Line Items]
Percent of total revenue	95.00%	97.00%	96.00%	96.00%

Stock Option Plan - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value	$ 0.2	$ 0.0
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	58,500
Stock options, unrecognized compensation cost	$ 0.9
Stock options, cost not yet recognized, remaining weighted average vesting period	10 months 28 days
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized, percentage	1.00%
Shares that remain available for future awards (in shares)	508,608
Maximum employee payroll deduction percentage	20.00%
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, vesting period	4 years
Stock options, unrecognized compensation cost	$ 6.0
Aggregate intrinsic value, vested	$ 0.4	$ 0.6
Weighted-average grant date fair value (in dollars per share)	$ 2.42	$ 8.66
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
Shares authorized, percentage	4.00%
Shares that remain available for future awards (in shares)	1,740,628

Stock Option Plan - Stock Option Activity (Details) - Stock options - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	1,421,235
Granted (in shares)	58,500
Exercised (in shares)	(93,335)
Forfeited (in shares)	(32,426)
Expired (in shares)	(359,448)
Outstanding, end of period (in shares)	994,526	1,421,235
Vested and expected to vest, end of period (in shares)	994,526
Options exercisable, end of period (in shares)	825,513
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding, beginning of period, Weighted Average Exercise Price (in dollars per share)	$ 12.94
Granted, Weighted Average Exercise Price (in dollars per share)	3.15
Exercised, Weighted Average Exercise Price (in dollars per share)	0.26
Forfeited, Weighted Average Exercise Price (in dollars per share)	14.38
Expired, Weighted Average Exercise Price (in dollars per share)	17.02
Outstanding, end of period, Weighted Average Exercise Price (in dollars per share)	12.03	$ 12.94
Vested and expected to vest, end of period (in shares), Weighted Average Exercise Price (in dollars per share)	12.03
Options exercised, end of period (in shares), Weighted Average Exercise Price (in dollars per share)	$ 12.24
Stock Options, Additional Disclosures [Abstract]
Outstanding, Weighted Average Remaining Contractual Term	6 years 10 months 24 days	7 years 1 month 2 days
Vested and expected to vest, Weighted Average Remaining Contractual Term	6 years 10 months 24 days
Options exercisable, Weighted Average Remaining Contractual Term	6 years 7 months 28 days
Outstanding, Aggregate Intrinsic Value	$ 349	$ 483
Vested and expected to vest, Aggregate Intrinsic Value	349
Options exercisable, Aggregate Intrinsic Value	$ 349

Other Financial Information - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Other Financial Information [Abstract]
Depreciation and amortization	$ 0.5	$ 0.3	$ 1.1	$ 0.6

Summary of Significant Accounting Policies - Securities (Details) - shares	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Class of Stock [Line Items]
Anti-dilutive securities excluded from computation (in shares)	3,062,931	3,173,725
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)	994,526	1,949,374
Restricted stock units
Class of Stock [Line Items]
Anti-dilutive securities excluded from computation (in shares)	1,598,578	784,940
Employee stock purchase plan
Class of Stock [Line Items]
Anti-dilutive securities excluded from computation (in shares)	60,719	30,303

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Commitment and Contingencies (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2021	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2021
Loss Contingencies [Line Items]
Purchase obligation, due in year one						$ 6,900
Purchase obligation, due in second year						8,000
Purchase obligation, due in third year						$ 9,200
Settlement charge		$ 700		$ 700
AHN Collaboration
Loss Contingencies [Line Items]
Collaboration agreement, collaboration expenses		$ 100	$ 100	$ 200	$ 200
Minimum \| Licensing Agreements
Loss Contingencies [Line Items]
Royalty obligation, percent of net sales		1.50%		1.50%
Maximum \| Licensing Agreements
Loss Contingencies [Line Items]
Royalty obligation, percent of net sales		7.00%		7.00%
Prometheus Laboratories
Loss Contingencies [Line Items]
Future minimum royalty commitment		$ 1,200		$ 1,200
Advance royalties payment		$ 100		$ 100
Prometheus Laboratories \| Minimum
Loss Contingencies [Line Items]
Royalty obligation, percent of net sales		2.50%		2.50%
Allegheny Health Network Research Institute
Loss Contingencies [Line Items]
Collaboration fee	$ 400

Unaudited Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 31,466	$ 62,391
Accounts receivable, net	16,235	6,077
Prepaid expenses and other current assets	3,570	4,143
Total current assets	51,271	72,611
Property and equipment, net	7,875	8,197
Operating lease right-of-use assets	4,412	4,885
Other assets	620	528
Total assets	64,178	86,221
Current liabilities:
Accounts payable	1,309	3,046
Accrued and other current liabilities	5,933	5,347
Operating lease liabilities	1,104	1,040
Borrowings-current portion	257	190
Total current liabilities	8,603	9,623
Borrowings-non-current portion, net of discounts and debt issuance costs	19,153	28,778
Non-current operating lease liabilities	3,923	4,493
Other non-current liabilities	597	867
Total liabilities	32,276	43,761
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized, no shares issued or outstanding as of June 30, 2023 and December 31, 2022	0	0
Common stock, $0.001 par value; 200,000,000 shares authorized as of June 30, 2023 and December 31, 2022; 16,858,194 and 16,549,984 shares issued and outstanding as of June 30, 2023 and December 31, 2022, respectively	17	17
Additional paid-in capital	300,113	297,970
Accumulated deficit	(268,228)	(255,527)
Total stockholders' equity	31,902	42,460
Total liabilities and stockholders' equity	$ 64,178	$ 86,221

Stockholders' Equity

6 Months Ended

Jun. 30, 2023

Equity [Abstract]

Stockholders' Equity

Common Stock

At The Market Sales Agreement

On September 15, 2022, the Company entered into a sales agreement (the Sales Agreement) with Cowen and Company, LLC, 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 June 30, 2023, the Company has not sold any shares of its common stock pursuant to the Sales Agreement.

Outstanding Warrants

The following equity classified warrants to purchase common stock were outstanding as of June 30, 2023:


	Shares	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	804,951	$	0.001	June 22, 2021	None
	1,214,059

During the three and six months ended June 30, 2023, no warrants to purchase common stock were exercised.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 14
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
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-Name Accounting Standards Codification
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
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+ Details

Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2023

Equity [Abstract]

Schedule of Outstanding Warrants

The following equity classified warrants to purchase common stock were outstanding as of June 30, 2023:


	Shares	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	804,951	$	0.001	June 22, 2021	None
	1,214,059

Other Financial Information - Prepaid Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Other Financial Information [Abstract]
Diagnostic testing supplies	$ 1,653	$ 1,795
Prepaid product royalties	39	40
Prepaid maintenance and insurance contracts	1,860	2,072
Other prepaid expenses and other current assets	18	236
Prepaid expenses and other current assets	$ 3,570	$ 4,143

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2023
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. The Company has not experienced any losses on its cash or cash equivalents.
Fair Value Measurements	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 value of the Company's long-term borrowings is determined by Level 2 inputs and based primarily on quoted market prices for the same or similar issues. As of June 30, 2023, the 2017 Term Loan (as defined below) had a carrying value of $18.5 million and a fair value of $19.1 million. 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 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 other long-term borrowing was $0.9 million and approximated its fair value as of June 30, 2023. As of December 31, 2022, the recorded value of the Company's other long term borrowing was $0.8 million and approximated its fair value.
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 of three months or less upon acquisition to be cash equivalents. These investments are stated at cost, which approximates fair value.
Long-lived Assets	Long-lived Assets The Company’s long-lived assets are comprised principally of its property and equipment and operating lease assets. The Company amortizes 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, into groupings, a determination which we principally make on the basis of whether the assets are specific to a particular test we offer or technology we are developing. If the Company identifies a change in the circumstances related to its long-lived assets that indicates the carrying value of any such asset may not be recoverable, the Company will perform an impairment analysis. A long-lived asset 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.
Revenue Recognition	Revenue Recognition Substantially all of the Company's revenue has been derived from sales of its testing products and is primarily comprised of a high volume of relatively low-dollar transactions. The Company primarily markets its testing products to rheumatologists and their physician assistants in the United States. The healthcare professionals who order the Company's testing products and to whom test results are reported are generally not responsible for payment for these products. The parties that pay for these services (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. Adjustments are recorded 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 three months ended June 30, 2023 and 2022 was a $1.5 million net revenue increase and a $1.2 million net revenue decrease, respectively, associated with changes in estimated variable consideration related to performance obligations satisfied in previous periods. Included in revenues for the six months ended June 30, 2023 and 2022 was a $1.8 million net revenue increase and a $1.6 million net revenue decrease, 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.
Research and Development	Research and DevelopmentCosts 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 $0.4 million and $0.6 million for the three months ended June 30, 2023 and 2022, respectively. For the six months ended June 30, 2023 and 2022, total advertising and marketing costs were approximately $0.7 million and $0.9 million, respectively. These costs are included in selling, general and administrative expenses in the accompanying condensed statements of operations.
Shipping and Handling Costs	Shipping and Handling Costs Costs incurred for shipping and handling are included in costs of revenue in the accompanying condensed statements of operations and totaled approximately $0.6 million and $0.7 million for the three months ended June 30, 2023 and 2022, respectively. For each of the six months ended June 30, 2023 and 2022, shipping and handling costs were approximately $1.3 million.
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.
Net Loss Per Share	Net Loss Per Share Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. 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, stock options, 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 three and six months ended June 30, 2023 and 2022, 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 and Recently Adopted Accounting Standards	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 June 2016, the FASB issued Accounting Standards Update (ASU) 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires the measurement of expected credit losses (based on historical experience, current conditions and reasonable forecasts) for financial instruments (such as accounts receivable) held at the reporting date which are carried at amortized cost. 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 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. The adoption did not have an impact on its condensed financial statements. 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). ASU 2020-06 eliminates the beneficial conversion and cash conversion accounting models for convertible instruments. It also amends the accounting for certain contracts in an entity’s own equity that are currently accounted for as derivatives because of specific settlement provisions. In addition, ASU 2020-06 modifies how particular convertible instruments and certain contracts that may be settled in cash or shares impact the diluted EPS computation. The amendments in ASU 2020-06 are effective for smaller reporting companies as defined by the SEC for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. The Company early adopted ASU 2020-06 as of January 1, 2023. The adoption did not have an impact on its condensed financial statements.

Stockholders' Equity - Narrative (Details) - USD ($) $ in Millions		3 Months Ended	6 Months Ended
	Sep. 15, 2022	Jun. 30, 2023	Jun. 30, 2023
Class of Stock [Line Items]
Exercise of common stock warrants (in shares)		0	0
Cowen Equity Distribution Agreement
Class of Stock [Line Items]
Proceeds from sale of stock	$ 50.0

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Other Financial Information

6 Months Ended

Jun. 30, 2023

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):


	June 30, 2023		December 31, 2022
Diagnostic testing supplies	$	1,653	$	1,795
Prepaid product royalties	39		40
Prepaid maintenance and insurance contracts	1,860		2,072
Other prepaid expenses and other current assets	18		236
Prepaid expenses and other current assets	$	3,570	$	4,143

Property and Equipment

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


	June 30, 2023		December 31, 2022
Furniture and fixtures	$	98	$	98
Laboratory equipment	6,458		5,136
Computer equipment and software	1,557		1,482
Leasehold improvements	5,284		5,223
Construction in progress	641		1,382
Total property and equipment	14,038		13,321
Less: accumulated depreciation and amortization	(6,163)		(5,124)
Property and equipment, net	$	7,875	$	8,197

Depreciation and amortization expense for the three months ended June 30, 2023 and 2022 was approximately $0.5 million and $0.3 million, respectively. For the six months ended June 30, 2023 and 2022, depreciation and amortization expense was approximately $1.1 million and $0.6 million, respectively.

Accrued and Other Current Liabilities

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


	June 30, 2023		December 31, 2022
Accrued payroll and related expenses	$	3,284	$	2,355
Accrued interest	130		142
Accrued purchases of goods and services	435		803
Accrued royalties	62		514
Accrued clinical study activity	121		162
Finance lease obligations, current portion	595		700
Legal accrual	700		—
Refund liability	254		445
Other accrued liabilities	352		226
Accrued and other current liabilities	$	5,933	$	5,347

Stock Option Plan (Tables)

6 Months Ended

Jun. 30, 2023

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 (in thousands)
Outstanding, December 31, 2022	1,421,235	$	12.94	7.09	$	483
Granted	58,500	$	3.15
Exercised	(93,335)	$	0.26
Forfeited	(32,426)	$	14.38
Expired	(359,448)	$	17.02
Outstanding, June 30, 2023	994,526	$	12.03	6.90	$	349
Vested and expected to vest, June 30, 2023	994,526	$	12.03	6.90	$	349
Options exercisable, June 30, 2023	825,513	$	12.24	6.66	$	349

Schedule of 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 (in thousands)
Outstanding, December 31, 2022	1,036,208	$	7.28	$	2,487
Awards granted	796,400	$	2.42
Awards released	(144,985)	$	12.01
Awards canceled	(89,045)	$	9.53
Outstanding, June 30, 2023	1,598,578	$	4.30	$	4,636

Schedule of Non-cash Stock-based Compensation Expense


	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Costs of revenue	$	63	$	59	$	116	$	103
Selling, general and administrative	874		1,203		1,705		2,321
Research and development	41		178		143		392
Total	$	978	$	1,440	$	1,964	$	2,816

Fair Value Measurements (Details) - Recurring - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Assets:
Total	$ 28,082	$ 59,538
Money market funds, included in cash and cash equivalents
Assets:
Money market funds, included in cash and cash equivalents	4,082	29,438
Certificate of deposit, included in cash and cash equivalents
Assets:
Money market funds, included in cash and cash equivalents	24,000	30,100
Level 1
Assets:
Total	28,082	59,538
Level 1 \| Money market funds, included in cash and cash equivalents
Assets:
Money market funds, included in cash and cash equivalents	4,082	29,438
Level 1 \| Certificate of deposit, included in cash and cash equivalents
Assets:
Money market funds, included in cash and cash equivalents	24,000	30,100
Level 2
Assets:
Total	0	0
Level 2 \| Money market funds, included in cash and cash equivalents
Assets:
Money market funds, included in cash and cash equivalents	0	0
Level 2 \| Certificate of deposit, included in cash and cash equivalents
Assets:
Money market funds, included in cash and cash equivalents	0	0
Level 3
Assets:
Total	0	0
Level 3 \| Money market funds, included in cash and cash equivalents
Assets:
Money market funds, included in cash and cash equivalents	0	0
Level 3 \| Certificate of deposit, included in cash and cash equivalents
Assets:
Money market funds, included in cash and cash equivalents	$ 0	$ 0

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2023

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):


	June 30, 2023
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds, included in cash and cash equivalents	$	4,082	$	4,082	$	—	$	—
Certificate of deposit, included in cash and cash equivalents	24,000		24,000		—		—
Total	$	28,082	$	28,082	$	—	$	—


	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	$	—	$	—

Summary of Significant Accounting Policies - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Cash and cash equivalents	$ 31,466	$ 62,391
Restricted cash	200	200
Total cash, cash equivalents and restricted cash	$ 31,666	$ 62,591	$ 76,487	$ 99,542

Unaudited Condensed Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2021		16,164,994
Beginning 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)		30,523
Issuance of stock from vested restricted stock units and payment of employees' taxes	(115)		(115)
Issuance of stock under Employee Stock Purchase Plan (in shares)		35,681
Issuance of stock under Employee Stock Purchase Plan	231		231
Stock-based compensation	1,376		1,376
Net loss	(10,272)			(10,272)
Ending balance (in shares) at Mar. 31, 2022		16,231,198
Ending balance at Mar. 31, 2022	76,156	$ 16	294,552	(218,412)
Beginning balance (in shares) at Dec. 31, 2021		16,164,994
Beginning balance at Dec. 31, 2021	84,936	$ 16	293,060	(208,140)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(24,937)
Ending balance (in shares) at Jun. 30, 2022		16,258,807
Ending balance at Jun. 30, 2022	62,824	$ 16	295,885	(233,077)
Beginning balance (in shares) at Mar. 31, 2022		16,231,198
Beginning balance at Mar. 31, 2022	76,156	$ 16	294,552	(218,412)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock from vested restricted stock units and payment of employees' taxes (in shares)		27,609
Issuance of stock from vested restricted stock units and payment of employees' taxes	(107)		(107)
Stock-based compensation	1,440		1,440
Net loss	(14,665)			(14,665)
Ending balance (in shares) at Jun. 30, 2022		16,258,807
Ending balance at Jun. 30, 2022	$ 62,824	$ 16	295,885	(233,077)
Beginning balance (in shares) at Dec. 31, 2022	16,549,984	16,549,984
Beginning balance at Dec. 31, 2022	$ 42,460	$ 17	297,970	(255,527)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock from vested restricted stock units and payment of employees' taxes (in shares)		113,378
Issuance of stock under Employee Stock Purchase Plan (in shares)		70,317
Issuance of stock under Employee Stock Purchase Plan	152		152
Exercise of stock options (in shares)		93,335
Exercise of stock options	27		27
Stock-based compensation	986		986
Net loss	(7,688)			(7,688)
Ending balance (in shares) at Mar. 31, 2023		16,827,014
Ending balance at Mar. 31, 2023	$ 35,937	$ 17	299,135	(263,215)
Beginning balance (in shares) at Dec. 31, 2022	16,549,984	16,549,984
Beginning balance at Dec. 31, 2022	$ 42,460	$ 17	297,970	(255,527)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ (12,701)
Ending balance (in shares) at Jun. 30, 2023	16,858,194	16,858,194
Ending balance at Jun. 30, 2023	$ 31,902	$ 17	300,113	(268,228)
Beginning balance (in shares) at Mar. 31, 2023		16,827,014
Beginning balance at Mar. 31, 2023	35,937	$ 17	299,135	(263,215)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock from vested restricted stock units and payment of employees' taxes (in shares)		31,180
Stock-based compensation	978		978
Net loss	$ (5,013)			(5,013)
Ending balance (in shares) at Jun. 30, 2023	16,858,194	16,858,194
Ending balance at Jun. 30, 2023	$ 31,902	$ 17	$ 300,113	$ (268,228)

Summary of Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue	$ 14,137	$ 7,606	$ 25,367	$ 18,000
Commercial
Disaggregation of Revenue [Line Items]
Revenue	7,484	4,510	11,699	10,933
Government
Disaggregation of Revenue [Line Items]
Revenue	4,189	1,139	8,615	3,259
Client
Disaggregation of Revenue [Line Items]
Revenue	2,273	1,755	4,680	3,346
Other
Disaggregation of Revenue [Line Items]
Revenue	$ 191	$ 202	$ 373	$ 462

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- 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
-Topic 924
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479941/924-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-40

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-41

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-4

+ Details

Cover - shares	6 Months Ended
Cover - shares	Jun. 30, 2023	Aug. 03, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2023
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 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
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		16,858,764
Entity Central Index Key	0001274737
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Amendment Flag	false

Unaudited Condensed Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2023	Dec. 31, 2022
Preferred stock
Par value (in dollars per share)	$ 0.001	$ 0.001
Shares authorized (in shares)	10,000,000	10,000,000
Shares outstanding (in shares)	0	0
Shares issued (in shares)	0	0
Common stock
Par value (in dollars per share)	$ 0.001	$ 0.001
Shares authorized (in shares)	200,000,000	200,000,000
Shares issued (in shares)	16,858,194	16,549,984
Shares outstanding (in shares)	16,858,194	16,549,984

Borrowings - Future Minimum Payments (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Debt Disclosure [Abstract]
2023 (remaining)	$ 950
2024	1,908
2025	1,928
2026	21,215
Total	26,001
Unamortized debt discount and issuance costs	(134)
Interest	(6,457)
Total borrowings, net of discounts and debt issuance costs	19,410
Less: Borrowings-current portion	(257)	$ (190)
Borrowings-non-current portion, net of discounts and debt issuance costs	$ 19,153	$ 28,778

Other Financial Information (Tables)

6 Months Ended

Jun. 30, 2023

Other Financial Information [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

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


	June 30, 2023		December 31, 2022
Diagnostic testing supplies	$	1,653	$	1,795
Prepaid product royalties	39		40
Prepaid maintenance and insurance contracts	1,860		2,072
Other prepaid expenses and other current assets	18		236
Prepaid expenses and other current assets	$	3,570	$	4,143

Schedule of Property and Equipment

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


	June 30, 2023		December 31, 2022
Furniture and fixtures	$	98	$	98
Laboratory equipment	6,458		5,136
Computer equipment and software	1,557		1,482
Leasehold improvements	5,284		5,223
Construction in progress	641		1,382
Total property and equipment	14,038		13,321
Less: accumulated depreciation and amortization	(6,163)		(5,124)
Property and equipment, net	$	7,875	$	8,197

Schedule of Accrued and Other Current Liabilities

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


	June 30, 2023		December 31, 2022
Accrued payroll and related expenses	$	3,284	$	2,355
Accrued interest	130		142
Accrued purchases of goods and services	435		803
Accrued royalties	62		514
Accrued clinical study activity	121		162
Finance lease obligations, current portion	595		700
Legal accrual	700		—
Refund liability	254		445
Other accrued liabilities	352		226
Accrued and other current liabilities	$	5,933	$	5,347