0000950170-23-010016 | 10-K | XBRL Viewer | Terns Pharmaceuticals INC

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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2022	Mar. 03, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Amendment Flag	false
Document Period End Date	Dec. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Entity Registrant Name	Terns Pharmaceuticals, Inc.
Entity Central Index Key	0001831363
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
ICFR Auditor Attestation Flag	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Small Business	true
Entity Common Stock, Shares Outstanding		56,669,596
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Shell Company	false
Entity File Number	001-39926
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	98-1448275
Entity Address Address Line1	1065 East Hillsdale Blvd.
Entity Address, Address Line Two	Suite 100
Entity Address, City or Town	Foster City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94404
City Area Code	650
Local Phone Number	525-5535
Entity Public Float			$ 46,808,820
Document Transition Report	false
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	TERN
Security Exchange Name	NASDAQ
Documents Incorporated By Reference	Portions of the information called for by Part III of this Annual Report on Form 10-K is hereby incorporated by reference from the definitive proxy statement for the registrant’s 2023 annual meeting of stockholders, which will be filed with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year ended December 31, 2022.
Auditor Firm ID	42
Auditor Location	San Jose, California
Auditor Name	Ernst & Young LLP

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 143,235	$ 47,699
Marketable securities	139,879	118,283
Prepaid expenses and other current assets	2,071	948
Total current assets	285,185	166,930
Property and equipment, net	757	1,046
Operating lease assets	1,047	0
Other assets	37	94
Total assets	287,026	168,070
Current liabilities:
Accounts payable	1,645	2,126
Accrued expenses and other current liabilities	6,162	4,694
Current portion of operating lease liabilities	661	0
Total current liabilities	8,468	6,820
Deferred rent, net of current portion	0	160
Taxes payable, non-current	1,071	787
Operating lease liabilities, non-current	544	0
Total liabilities	10,083	7,767
Commitments and contingencies
Stockholders' equity:
Common stock, $0.0001 par value, 150,000,000 shares authorized at December 31, 2022 and 2021; 53,723,171 and 25,269,271 shares issued and outstanding at December 31, 2022 and 2021, respectively	5	3
Additional paid-in capital	520,178	342,711
Accumulated other comprehensive loss	(822)	(338)
Accumulated deficit	(242,418)	(182,073)
Total stockholders' equity	276,943	160,303
Total liabilities and stockholders' equity	$ 287,026	$ 168,070

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, authorized	150,000,000	150,000,000
Common stock, shares issued	53,723,171	25,269,271
Common stock, shares outstanding	53,723,171	25,269,271

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Revenue:
License revenue	$ 0	$ 1,000
Operating expenses:
Research and development	39,617	31,311
General and administrative	22,412	19,549
Total operating expenses	62,029	50,860
Loss from operations	(62,029)	(49,860)
Other income
Interest income	2,110	170
Other (expense) income, net	(68)	40
Total other income, net	2,042	210
Loss before income taxes	(59,987)	(49,650)
Income tax expense	(358)	(508)
Net loss	$ (60,345)	$ (50,158)
Net loss per share, basic	$ (1.67)	$ (2.21)
Net loss per share, diluted	$ (1.67)	$ (2.21)
Weighted average common stock outstanding, basic	36,033,045	22,705,948
Weighted average common stock outstanding, diluted	36,033,045	22,705,948
Other comprehensive loss:
Net loss	$ (60,345)	$ (50,158)
Unrealized loss on available-for-sale securities, net of tax	(320)	(194)
Foreign exchange translation adjustment, net of tax	(164)	(20)
Comprehensive loss	$ (60,829)	$ (50,372)

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Accumulated Other Comprehensive Loss	Accumulated deficit	Series A convertible preferred stock	Series B convertible preferred stock	Series C convertible preferred stock
Balances at Dec. 31, 2020	$ (117,441)		$ 14,598	$ (124)	$ (131,915)
Balance at Beginning of period at Dec. 31, 2020						$ 30,000	$ 68,995	$ 87,038
Balance at Beginning of period (in shares) at Dec. 31, 2020						2,857,142	2,600,645	7,500,665
Balance at Beginning of period (in shares) at Dec. 31, 2020		337,508
Conversion of preferred stock to common stock upon closing of the initial public offering	186,033	$ 2	186,031
Temporary equity, conversion of convertible preferred stock into common stock upon closing of the initial public offering (in shares)						(2,857,142)	(2,600,645)	(7,500,665)
Temporary equity, conversion of convertible preferred stock into common stock upon closing of the initial public offering						$ (30,000)	$ (68,995)	$ (87,038)
Conversion of preferred stock to common stock upon closing of the initial public offering (in shares)		16,079,230
Sale of common stock in initial public offering, net of issuance costs	133,023	$ 1	133,022
Sale of common stock in initial public offering, net of issuance costs (in shares)		8,625,000
Exercise of stock options	914		914
Exercise of stock options (in shares)		156,104
Vesting of restricted stock (in shares)		71,429
Stock-based compensation expense	8,146		8,146
Unrealized loss on available-for-sale securities	(194)			(194)
Foreign exchange translation adjustment	(20)			(20)
Net loss	(50,158)				(50,158)
Balances at Dec. 31, 2021	160,303	$ 3	342,711	(338)	(182,073)
Balance at end of period (in shares) at Dec. 31, 2021		25,269,271
Exercise of stock options (in shares)		10,000
Stock-based compensation expense	10,768		10,768
Unrealized loss on available-for-sale securities	(320)			(320)
Issuance of common stock and pre-funded warrants, net of issuance costs (In Shares)		12,250,000
Issuance of common stock and pre-funded warrants, net of issuance costs value	60,719	$ 1	60,718
Issuance of common stock, net of issuance costs (In Shares)		11,902,500
Issuance of common stock, net of issuance costs value	80,847	$ 1	80,846
Issuance of common stock in at-the-market offering, net of issuance costs (In Shares)		4,122,628
Issuance of common stock in at-the-market offering, net of issuance costs value	24,892		24,892
Issuance of common stock under employee stock purchase plan (In Shares)		168,772
Issuance of common stock under employee stock purchase plan value	243		243
Foreign exchange translation adjustment	(164)			(164)
Net loss	(60,345)				(60,345)
Balances at Dec. 31, 2022	$ 276,943	$ 5	$ 520,178	$ (822)	$ (242,418)
Balance at end of period (in shares) at Dec. 31, 2022		53,723,171

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Stock issuance cost	$ 268	$ 3,339
Pre-funded warrants
Stock issuance cost	426
At-the-Market Offering
Stock issuance cost	$ 101

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net loss	$ (60,345)	$ (50,158)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	10,768	8,146
Depreciation and amortization expense	484	512
Amortization on marketable securities, net	81	879
Change in deferred taxes and uncertain tax positions	392	219
Amortization of operating lease assets	548	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,121)	238
Other assets	0	37
Accounts payable	(722)	1,727
Accrued expenses and other current liabilities	1,416	(3,367)
Operating lease liabilities	(610)	0
Deferred rent	0	(60)
Net cash used in operating activities	(49,109)	(41,827)
Cash flows from investing activities:
Purchase of property and equipment	(275)	(340)
Purchase of investments	(139,731)	(166,297)
Proceeds from sales and maturities of investments	117,734	46,941
Net cash used in investing activities	(22,272)	(119,696)
Cash flows from financing activities:
Net proceeds from the issuance of common stock and pre-funded warrants	61,145	0
Net proceeds from the issuance of common stock	81,115	0
Net proceeds from issuance of common stock in at-the-market offering	24,993	0
Payment of deferred offering costs	(401)	(2,721)
Proceeds from the issuance of common stock under employee stock purchase plan	243	0
Net proceeds from initial public offering	0	136,362
Proceeds from notes receivable	0	12,718
Payment of loans payable	0	(12,880)
Proceeds from stock option exercises	0	914
Net cash provided by financing activities	167,095	134,393
Effect of exchange rate changes on cash and cash equivalents	(178)	(25)
Net increase (decrease) in cash and cash equivalents	95,536	(27,155)
Cash and cash equivalents at beginning of period	47,699	74,854
Cash and cash equivalents at end of period	143,235	47,699
Supplemental disclosure of cash flow information:
Cash paid for amounts included in the measurement of lease liabilities	688	0
Cash paid for taxes	3	238
Supplemental disclosure of noncash investing and financing activities:
Right-of-use assets obtained in exchange for lease liabilities	1,595	0
Deferred offering costs included in accounts payable and accrued expense	394	0
Conversion of preferred stock to common stock upon closing of the initial public offering	0	186,033
Purchases of property and equipment on trade vendor credit	$ 0	$ 38

Nature of the Business, Basis of Presentation and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Nature of the Business, Basis of Presentation and Summary of Significant Accounting Policies

Nature of the Business

Terns Pharmaceuticals, Inc. (Terns) is a clinical-stage biopharmaceutical company developing a portfolio of small-molecule product candidates to address serious diseases including oncology, non-alcoholic steatohepatitis (NASH) and obesity.

Terns was incorporated as an exempted company in the Cayman Islands in December 2016. In December 2020, the Company effected a de-registration of the Company in the Cayman Islands and a domestication in the State of Delaware (the "Domestication"), pursuant to which it became a Delaware corporation. Terns owns all of the share capital of Terns Pharmaceutical HongKong Limited (Terns Hong Kong) and Terns, Inc., a Delaware corporation (Terns U.S. Opco). Terns Hong Kong holds all of the share capital of Terns China Biotechnology Co., Ltd. (organized in Shanghai, People’s Republic of China (PRC)) (Terns China) and Terns (Suzhou) Biotechnology Co., Ltd. (organized in Suzhou, PRC) (Terns Suzhou).

The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions.

Basis of Presentation

The accompanying consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) and include the accounts of Terns and its wholly owned subsidiaries Terns U.S. Opco and Terns Hong Kong and its wholly owned subsidiaries Terns China and Terns Suzhou. The Company’s consolidated financial statements have been prepared in conformity with U.S. GAAP. All intercompany balances and transactions have been eliminated in consolidation.

Initial Public Offering

In February 2021, the Company completed an initial public offering (the “IPO”) of 8,625,000 shares of its common stock, including the exercise in full by the underwriters of their option to purchase up to 1,125,000 additional shares of common stock, for net proceeds of $133.0 million, after deducting underwriting discounts and commissions and offering expenses, and its shares started trading on the Nasdaq Global Select Market under the ticker symbol “TERN.” Upon closing of the IPO, all of the Company's outstanding shares of convertible preferred stock automatically converted into an aggregate of 16,079,230 shares of common stock.

At-the-Market Offering

In March 2022, the Company entered into a Sales Agreement with Cowen and Company, LLC (Cowen) as sales agent, pursuant to which the Company has the ability to offer and sell, from time to time, through Cowen, shares of its common stock having an aggregate offering price of up to $75.0 million in an at-the-market offering. The shares are offered pursuant to the Company's shelf registration statement on Form S-3 filed with the Securities and Exchange Commission, or SEC. There were 4,122,628 shares of the Company's common stock sold for aggregate net proceeds of $24.9 million, after deducting commissions and offering expenses, pursuant to this agreement through December 31, 2022. In February 2023, the Company sold an additional 2,929,922 shares of the Company's common stock for aggregate net proceeds of $27.9 million after deducting commissions and offering expenses.

August 2022 Financing

In August 2022, the Company issued 12,250,000 shares of its common stock at a price of $2.42 per share and, to certain investors in lieu of common stock, pre-funded warrants to purchase 14,630,000 shares of common stock at a price of $2.4199 per pre-funded warrant. The purchase price per share of each pre-funded warrant represents the per share offering price for the common stock, minus the $0.0001 per share exercise price of such pre-funded warrant. Aggregate net proceeds were $60.7 million after deducting underwriting discounts and commissions and offering expenses.

The pre-funded warrants were classified as a component of permanent stockholders’ equity within additional paid-in capital and were recorded at the issuance date using a relative fair value allocation method. The pre-funded warrants are equity classified because they (i) are freestanding financial instruments that are legally detachable and separately exercisable from the equity instruments, (ii) are immediately exercisable, (iii) do not embody an obligation for the Company to repurchase its shares, (iv) permit the holders to receive a fixed number of shares of common stock upon exercise, (v) are indexed to the Company’s common stock and (vi) meet the equity classification criteria. In addition, such pre-funded warrants do not provide any guarantee of value or return. The Company valued the pre-funded warrants at issuance, concluding that their sales price approximated their fair value, and allocated net proceeds from the sale proportionately to the common stock and pre-funded warrants, of which $33.0 million was allocated to the pre-funded warrants and recorded as a component of additional paid-in capital.

December 2022 Financing

In December 2022, the Company entered into an Underwriting Agreement with Jefferies LLC and Cowen and Company, LLC, as representatives of the several underwriters, relating to the underwritten public offering of 10,350,000 shares of the Company's common stock at a public offering price per share of $7.25. Under the terms of the Underwriting Agreement, the Company granted the underwriters an option, exercisable within 30 days from the date of the Underwriting Agreement, to purchase up to 1,552,500 additional shares of common stock, which the Underwriters exercised in full. Aggregate net proceeds were $80.8 million after deducting underwriting discounts and commissions and offering expenses.

Certificate of Incorporation

Prior to the IPO, the Company’s certificate of incorporation adopted in December 2020 in connection with the Domestication (the “December 2020 Charter”) authorized the Company to issue the following shares of capital stock: (i) 299,700,000 shares of common stock, (ii) 40,000,000 shares of Series A convertible preferred stock, (iii) 36,409,088 shares of Series B convertible preferred stock and (iii) 111,619,996 shares of Series C convertible preferred stock. All classes of stock under the December 2020 Charter were authorized at a par value of $0.0001.

In February 2021, the Company’s amended and restated certificate of incorporation filed with the Secretary of State of the State of Delaware became effective in connection with the closing of the IPO. Under the amended and restated certificate of incorporation, the Company is authorized to issue 150,000,000 shares of common stock and 10,000,000 shares of preferred stock. All classes of stock have a par value of $0.0001.

Reverse Stock Split

In January 2021, the Company filed an amended and restated certificate of incorporation to effectuate a reverse split of shares of the Company’s common stock and convertible preferred stock on a 1-for-14 basis (the “Reverse Stock Split”). The par value and the number of authorized shares of the convertible preferred stock and common stock were not adjusted as a result of the Reverse Stock Split. All issued and outstanding common stock, options to purchase common stock and per share amounts contained in the consolidated financial statements have been retroactively adjusted to give effect to the Reverse Stock Split for all periods presented.

Impact of the COVID-19 Pandemic

The COVID-19 pandemic continues to evolve. The COVID-19 virus and new variants that emerge continue to impact countries worldwide, including the United States and China where the Company has business operations. The extent of the impact of the COVID-19 pandemic on business, operations and development timelines and plans remains uncertain, and will depend on certain developments, including the duration and continuation of the outbreak and its impact on the Company’s development activities, planned clinical trial enrollment, future trial sites, contract research organizations (CROs), third-party manufacturers and other third parties with whom the Company conducts business, as well as its impact on regulatory authorities and the Company’s key scientific and management personnel. The ultimate impact of the COVID-19 pandemic or a similar health epidemic is highly uncertain and subject to change. To the extent possible, the Company is and plans to conduct business as usual, with any necessary or advisable modifications to employee travel and to the on-site and in-person activities of the Company's personnel. The Company will continue to actively monitor the evolving situation related to the COVID-19 pandemic and will take necessary actions that alter the Company’s operations, including those that may be required by federal, state or local authorities in the United States and China, or that the Company determines are in the best interest of its employees and other third parties with whom the Company conducts business. At this point, the extent to which the COVID-19 pandemic will affect the Company’s business, operations and development timelines and plans, including the resulting impact on expenditures and capital needs, remains uncertain.

Summary of Significant Accounting Policies

Revenue Recognition

To determine revenue recognition for arrangements, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that it will collect the consideration it is entitled to in exchange for the goods and services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract, determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied.

The Company enters into corporate collaborations under which it may obtain upfront license fees, research and development funding, and development, regulatory and commercial milestone payments and royalty payments. The Company’s performance obligations under these arrangements may include licenses of intellectual property, distribution rights, research and development services, delivery of manufactured product and/or participation on joint steering committees.

Licenses of intellectual property

If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from upfront license fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgement to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring proportional performance for purposes of recognizing revenue from non-refundable, upfront fees. The Company evaluates the measure of proportional performance each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition.

Milestone payments

At the inception of each arrangement that includes development, regulatory or commercial milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price. The Company considers two alternatives to use when estimating the amount of variable consideration: the expected value method and the most likely amount method. Under the expected value method, an entity considers the sum of probability-weighted amounts in a range of possible consideration amounts. Under the most likely amount method, an entity considers the single most likely amount in a range of possible consideration amounts. Whichever method is used, it should be consistently applied throughout the life of the contract; however, it is not necessary for the Company to use the same approach for all contracts. The Company expects to use the most likely amount method for development and regulatory milestone payments. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s or the licensee’s control, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis. The Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability or achievement of each such milestone and any related constraint, and if necessary, adjusts its estimates of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment.

Commercial milestones and royalties

For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and in which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue when the related sales occur. To date, the Company has not recognized any royalty revenue resulting from its collaboration arrangements.

Upfront payments and fees are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until the Company performs its obligations under these arrangements. Amounts payable to the Company are recorded as accounts receivable when the Company’s right to consideration is unconditional.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying consolidated financial statements include, but are not limited to, the estimates for accruals of research and development expenses, accrual of research contract costs, unrecognized tax benefits, fair value of common stock and stock option valuations. On an ongoing basis, the Company evaluates its estimates and judgments, using historical and anticipated results and trends and on various other assumptions that management believes to be reasonable under the circumstances. Actual results could materially differ from those estimates.

Cash, Cash Equivalents and Marketable Securities

Cash and cash equivalents consist of standard checking accounts and money market funds. The Company considers all highly liquid investments with an original maturity of 90 days or less at the date of purchase to be cash equivalents.

The Company classifies as available-for-sale marketable securities with a remaining maturity when purchased of greater than three months. The Company’s marketable securities are maintained by investment managers and consist of U.S. government and non-U.S. government securities, corporate debt securities and commercial paper. Debt securities are carried at fair value with the unrealized gains and losses included in other comprehensive loss as a component of stockholders’ equity until realized. Any premium arising at purchase is amortized to the earliest call date and any discount arising at purchase is accreted to maturity. Amortization and accretion of premiums and

discounts are recorded in interest income and/or expense. Realized gains and losses on debt securities are determined using the specific identification method and are included in other (expense) income, net.

If any adjustment to fair value reflects a decline in value of the investment, the Company considers all available evidence to evaluate the extent to which the decline is “other-than-temporary” and, if so, marks the investment to market through a charge to the Company’s consolidated statements of operations and comprehensive loss.

The fair value and amortized cost of marketable securities by major security type is as follows:


	December 31, 2022
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	23,029	$	—	$	—		$	23,029
U.S. government securities		44,555		31		(383	)		44,203
Non-U.S. government securities		3,024		—		(16	)		3,008
Corporate debt securities		36,411		—		(146	)		36,265
Commercial paper		56,403		—		—			56,403
Total	$	163,422	$	31	$	(545	)	$	162,908

Classified as:
Cash equivalents								$	23,029
Marketable securities									139,879
Total								$	162,908

	December 31, 2021
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	33,239	$	—	$	—		$	33,239
U.S. government securities		36,322		—		(130	)		36,192
Non-U.S. government securities		11,194		—		(12	)		11,182
Corporate debt securities		39,495		—		(52	)		39,443
Commercial paper		31,466		—		—			31,466
Total	$	151,716	$	—	$	(194	)	$	151,522

Classified as:
Cash equivalents								$	33,239
Marketable securities									118,283
Total								$	151,522

Unrealized losses on marketable securities have not been recognized into income because the issuers’ securities are of high credit quality and any decline in fair value is due to market conditions and/or changes in interest rates. The Company does not intend to sell and it is likely that the Company will not be required to sell the securities prior to the anticipated recovery of their amortized cost basis. The fair value is expected to recover as the marketable securities approach maturity.

Operating Leases and Rent Expense

At the inception of a contractual arrangement, the Company determines whether the contract contains a lease by assessing whether there is an identified asset and whether the contract conveys the right to control the use of the identified asset in exchange for consideration over a period of time. If both criteria are met, upon lease commencement, the Company records a lease liability which represents the Company’s obligation to make lease payments arising from the lease, and a corresponding right-of-use (“ROU”) asset which represents the Company’s right to use an underlying asset during the lease term.

Operating lease right-of-use assets and liabilities are recognized on the balance sheet at the lease commencement date based on the present value of the future minimum lease payments over the lease term. In determining the net present value of the lease payments, the Company uses its incremental borrowing rate applicable to the underlying asset unless the implicit rate is readily determinable. Any lease incentives received are deferred and recorded as a reduction of the ROU asset and amortized over the term of the lease. The Company does not separate lease and non-lease components and instead treats them as a single component. Rent expense, comprised of amortization of the ROU asset and the implicit interest accreted on the operating lease liability, is recognized on a straight-line basis over the lease term. The Company determines the lease term as the noncancellable period of the lease and may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise such options.

The Company elected to not apply the recognition requirements of the new leasing standard to short term leases with terms of 12 months or less. As a result, leases with a term of 12 months or less are not recognized on the balance sheet.

Classification of Convertible Preferred Stock

The holders of Series A, Series B and Series C convertible preferred stock, which were outstanding prior to the IPO, had certain liquidation rights in the event of a deemed liquidation that, in certain situations, were not solely within the control of the Company and would call for the redemption of the then outstanding convertible preferred stock. Therefore, the Series A, Series B and Series C convertible preferred stock were classified outside of stockholders’ equity on the consolidated balance sheets. In February 2021, upon the completion of the IPO, all the outstanding shares of convertible preferred stock converted into common stock and the Company does not have any shares of preferred stock outstanding.

Research and Development Expenses

Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred to discover, research and develop drug candidates, including personnel expenses, stock-based compensation expense, allocated facility-related and depreciation expenses, third-party license fees and external costs, including fees paid to consultants and contract research organizations, or CROs, in connection with nonclinical studies and clinical trials and other related clinical trial fees, such as for investigator grants, patient screening, laboratory work, clinical trial database management, clinical trial material management and statistical compilation and analysis. Non-refundable prepayments for goods or services that will be used or rendered for future research and development activities are recorded as prepaid expenses. Such amounts are recognized as an expense as the goods are delivered or the related services are performed, or until it is no longer expected that the goods will be delivered, or the services rendered. Costs incurred in obtaining technology licenses are charged immediately to research and development expense if the technology licensed has not reached technological feasibility and has no alternative future uses.

The Company has from time to time entered into various research and development and other agreements with commercial firms, researchers, universities and others for provisions of goods and services. These agreements are generally cancelable, and the related costs are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research and development costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies or clinical trials, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ materially from the Company’s estimates. Since inception, the Company’s historical accrual estimates have not been materially different from the actual costs.

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities included the following:


	December 31,
(in thousands)	2022		2021
Research and development costs	$	1,209	$	1,570
Accrued professional fees		925		363
Compensation and benefit costs		3,843		2,403
Other		185		358
Total accrued expenses and other current liabilities	$	6,162	$	4,694

Income Taxes

The provision for income taxes primarily relates to projected federal, state and foreign income taxes. To determine the quarterly provision for income taxes, the Company uses an estimated annual effective tax rate, which is generally based on expected annual income and statutory tax rates in the various jurisdictions in which the Company operates. In addition, the tax effects of certain significant or unusual items are recognized discretely in the quarter during which they occur and can be a source of variability in the effective tax rates from quarter to quarter.

Income taxes are computed using the asset and liability approach that requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the Company’s financial statements. In estimating future tax consequences, the Company considers all expected future events including the enactment of changes in tax laws or rates. A valuation allowance is recorded, if necessary, to reduce net deferred tax assets to their realizable values if management does not believe it is more likely than not that the net deferred tax assets will be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, and ongoing prudent and feasible tax planning strategies in assessing the amount of the valuation allowance. When the Company establishes or reduces the valuation allowance against its deferred tax assets, its provision for income taxes will increase or decrease, respectively, in the period such determination is made.

The Company assesses accounting for uncertainty in income taxes by modeling for the recognition, measurement and disclosure in financial statements any uncertain income tax positions that the Company has taken or expects to take on a tax return. As of each balance sheet date, unresolved uncertain tax positions are reassessed. The Company accrues interest and related penalties, if applicable, on all tax exposures for which reserves have been established consistent with jurisdictional tax laws.

Comprehensive Loss

Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources.

Stock-Based Compensation

Stock-based compensation expense, including grants of stock options and restricted stock awards issued under the Company’s equity incentive plan and rights to acquire stock granted under the Company’s employee stock purchase plan (ESPP), is measured at the grant date based on the fair value of the awards and is recognized as an expense on a straight-line basis over the requisite service period, which is generally the vesting period. The Company’s determination of the fair value of stock options with time-based vesting and rights to acquire stock under the ESPP utilizes the Black-Scholes option-pricing model. The Company lacks sufficient company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. The Company estimates risk-free rates using the implied yield currently available on U.S. Treasury zero-coupon issues with a remaining term equal to the expected term and dividend yield using the Company’s expectations and historical data. The Company uses the simplified method to calculate the expected term of stock option grants as the Company has limited historical information from which to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants. Under the simplified method, the expected term is estimated to be the mid-point between the vesting date and the contractual term of the option. The fair value of each stock option grant and right to acquire stock under the ESPP is calculated based upon the Company’s common stock valuation on the date of the grant. The Company accounts for forfeitures of stock option grants as they occur.

Net Loss Per Share of Common Stock

The Company follows the two-class method when computing net income (loss) per share of common stock as the Company has issued shares that meet the definition of participating securities. The two-class method determines net income (loss) per share of common stock for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed.

Basic net income (loss) per share of common stock is computed by dividing the net income (loss) per share of common stock by the weighted average number of shares of common stock outstanding for the period. The weighted-average shares of common stock outstanding as of December 31, 2022 included pre-funded warrants to purchase up to an aggregate of 14,630,000 shares of common stock that were issued in connection with the August 2022 Financing.

Diluted net income (loss) per share of common stock is computed by adjusting net income (loss) to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net loss per share of common stock is computed by dividing the diluted net loss by the weighted average number of shares of common stock outstanding for the period, including potential dilutive shares. For purposes of this calculation, outstanding stock options and convertible preferred stock are considered potential dilutive shares. The Company’s convertible preferred stock outstanding prior to the IPO contractually entitled the holders of such shares to participate in dividends but did not contractually require the holders of such shares to participate in losses of the Company. Accordingly, in periods in which the Company reported a net loss, such losses were not allocated to such securities.

The Company reported a net loss for the years ended December 31, 2022 and 2021. In periods in which the Company reported a net loss, diluted net loss per share of common stock was the same as basic net loss per share of common stock, since dilutive shares were not assumed to have been issued if their effect is anti-dilutive. The Company excluded the following potential shares of common stock, presented based on amounts outstanding at each period end, from the computation of diluted net loss attributable to common stockholders per share of common stock for the periods indicated because including them would have had an anti-dilutive effect:


	December 31,
	2022		2021
Options to purchase common stock		4,823,928		3,577,485
Unvested restricted stock units		128,280		—
Shares issuable under employee stock purchase plan		25,326		6,717
Total		4,977,534		3,584,202

Deferred Offering Costs

The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated.

After consummation of the equity financing, these costs are recorded as a reduction to the carrying value of stockholders’ equity as a reduction of additional paid-in capital or equity generated as a result of such offering. Should an in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the consolidated statements of operations and comprehensive loss.

Property and Equipment

Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives. The general range of useful lives of equipment is 3 to 5 years.

When assets are sold or retired, the cost and related accumulated depreciation are removed from the accounts, with any resulting gain or loss recorded in operating expenses in the consolidated statements of operations and comprehensive loss. Costs of repairs and maintenance are expensed as incurred.

Property and equipment, net consisted of the following:


		December 31,
(in thousands)	Estimated Useful Lives	2022			2021
Leasehold improvements	Shorter of remaining life of lease or useful life of asset	$	758		$	928
Furniture and fixtures	5 years		294			281
Computer equipment	3 years		203			202
Office equipment	5 years		146			102
Lab equipment	3 to 5 years		758			718
Property and equipment, gross			2,159			2,231
Less: Accumulated depreciation			(1,402	)		(1,185	)
Total property and equipment, net		$	757		$	1,046

The Company recognized depreciation expense related to these assets of $0.5 million during each of the years ended December 31, 2022 and 2021.

Impairment of Long-Lived Assets

The Company’s long-lived assets are evaluated for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset or asset group may not be recoverable. Recoverability of an asset to be held and used is measured by a comparison of the carrying amount of an asset or asset group to the future undiscounted cash flows expected to be generated by the asset or asset group. If such asset is considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds its fair value. There were no impairments of long-lived assets for any of the periods presented.

Functional Currencies and Foreign Currency Translation

The Company’s reporting currency is U.S. dollars. The functional currency of Terns U.S. Opco and Terns H.K. is U.S. dollars, while the functional currency of Terns Suzhou and Terns China is the Chinese Yuan (CNY). Transactions denominated in other than the functional currencies are remeasured into the functional currency of the entity at the exchange rates prevailing on the transaction dates. Financial assets and liabilities denominated in other than the functional currency are remeasured at the balance sheet date exchange rate. The resulting exchange rate differences are recorded in the consolidated statements of operations and comprehensive loss as a foreign exchange related gain or loss.

Assets and liabilities of Terns Suzhou and Terns China are translated into U.S. dollars at the balance sheet date exchange rates, while income and expense items are translated at the average exchange rates prevailing during the fiscal year. Translation adjustments arising from these are reported as foreign currency translation adjustments and are shown as accumulated other comprehensive loss on the consolidated balance sheets.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentration of credit risk consist of cash, cash equivalents and marketable securities. The Company invests its excess cash in accounts held at large financial institutions that management believes to be of high credit quality. The Company has not experienced any losses on such deposits.

Patent Costs

All patent-related costs incurred in connection with filing and prosecuting patent applications are expensed as incurred due to the uncertainty of the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses in the consolidated statements of operations and comprehensive loss.

Commitments and Contingencies

From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of business. 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. For all periods presented, the Company was not a party to any pending material litigation or other material legal proceedings.

Recently Adopted Accounting Pronouncements

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (ASU 2016-02), which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less may be accounted for similar to existing guidance for operating leases today. For non-public entities, ASU 2016-02 is effective for annual reporting periods, and interim periods within those fiscal years, beginning after December 15, 2021, and early adoption is permitted. Under the JOBS Act, emerging growth companies have extended transition periods available for complying with new or revised accounting standards.

The Company adopted the new standard on January 1, 2022 using the effective date as the date of initial application. Consequently, prior period amounts were not adjusted and continue to be reported in accordance with historical accounting policies under ASC 840: Leases (Topic 840). The Company elected the package of practical expedients under which the Company has not reassessed prior conclusions about lease identification, lease classification and initial direct costs. Additionally, the Company made a policy election that does not recognize ROU assets and lease liabilities related to leases with a term of 12 months or less. The Company has elected to not separate lease and non-lease components and instead treat them as a single component. The pattern of recognition for operating leases within the consolidated statements of comprehensive loss has not significantly changed. Upon adoption, the Company recognized operating liabilities of $1.7 million, with corresponding ROU assets of $1.5 million based on the present value of the remaining minimum rental payments under current leasing standards for existing operating leases. The Company’s current operating lease portfolio is primarily comprised of property leases.

Recently Issued Accounting Pronouncements Not Yet Adopted

In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13), which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss methodology, which will result in more timely recognition of credit losses. For non-public entities, ASU 2016-13 is effective for annual reporting periods, and interim periods within those fiscal years, beginning after December 15, 2022. Under the JOBS Act, emerging growth companies have extended transition periods available for complying with new or revised accounting standards. The Company will adopt the new standard on January 1, 2023 with no material impact on the Company's consolidated financial statements and related disclosures.

Fair Value Measurements

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The three levels of inputs that may be used to measure fair value are defined below:

•

Level 1—Quoted prices in active markets for identical assets or liabilities at the measurement date.

•

Level 2—Inputs other than quoted prices included in Level 1 that are observable for the asset or liability, such as quoted prices for similar assets or liabilities, 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 assets or liabilities.

•

Level 3—Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.

The carrying values of the Company’s other assets, accounts payable and accrued expenses and other current liabilities approximate their fair values due to the short-term nature of these assets and liabilities.

The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis:


	As of December 31, 2022:
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents
Cash in bank balances	$	120,206	$	—	$	—	$	120,206
Money market funds		23,029		—		—		23,029
Total cash and equivalents	$	143,235	$	—	$	—	$	143,235
Marketable securities
U.S. government securities	$	—	$	44,203	$	—	$	44,203
Non-U.S. government securities		—		3,008		—		3,008
Corporate debt securities		—		36,265		—		36,265
Commercial paper		—		56,403		—		56,403
Total marketable securities	$	—	$	139,879	$	—	$	139,879

	As of December 31, 2021:
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents
Cash in bank balances	$	14,460	$	—	$	—	$	14,460
Money market funds		33,239		—		—		33,239
Total cash and equivalents	$	47,699	$	—	$	—	$	47,699
Marketable securities
U.S. government securities	$	—	$	36,192	$	—	$	36,192
Non-U.S. government securities		—		11,182		—		11,182
Corporate debt securities		—		39,443		—		39,443
Commercial paper		—		31,466		—		31,466
Total marketable securities	$	—	$	118,283	$	—	$	118,283

The aggregate amortized cost and fair value of marketable securities as of December 31, 2022, by contractual maturity, are as follows:


(in thousands)	Amortized Cost		Fair Value
Due in one year or less	$	136,501	$	136,008
Due after one year through two years		3,892		3,871
Total marketable securities	$	140,393	$	139,879

During the years ended December 31, 2022 and 2021, there were no transfers between Level 1, Level 2 and Level 3.

- 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

Leases

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

Leases

In March 2019, the Company entered into a lease agreement for office space in Foster City, California which expires October 2024. The Company has the option to extend the lease agreement for a period of five years. Additionally, the Company leases office space in Shanghai and Suzhou China.

Components of lease cost are as follows:


	Year Ended
(in thousands)	December 31, 2022
Operating lease cost	$	610
Short-term cost		43
Total lease cost	$	653

Weighted-average remaining lease term		1.79
Weighted-average discount rate		6.00	%

The Company's future minimum lease payments are as follows:


(in thousands)	Operating Leases
2023	$	850
2024		559
2025 and thereafter		—
Total lease payments		1,409
Less: Imputed interest		(204	)
Present value of lease liabilities		1,205
Less: Current portion of lease liabilities		(661	)
Total lease liabilities, non-current	$	544

The future minimum annual lease payments required under the Company’s existing operating lease agreements as of December 31, 2021 prior to the adoption of ASC 842 were as follows:


(in thousands)	Operating Leases
2022	$	669
2023		652
2024		559
2025 and thereafter		—
Total	$	1,880

Loans Payable

12 Months Ended

Dec. 31, 2022

Debt Disclosure [Abstract]

Loans Payable

2020 Notes

In May 2020, the Company issued convertible promissory notes (2020 Notes) in the aggregate amount of $15.0 million. The 2020 Notes had an interest rate of 10.0% per annum, were unsecured, and were due and payable, including accrued interest, in May 2021. In connection with the Series C Convertible Preferred Stock Financing, the 2020 Notes, totaling unpaid principal and accrued interest of $15.9 million, converted into 1,366,820 shares of Series C convertible preferred stock.

Bridge Loan

In May 2020, the Company entered into a bridge loan with Terns China (Bridge Loan) for aggregate proceeds of $1.8 million, payable in renminbi (RMB) at an established USD/RMB exchange rate, based on an average of the previous five working days before May 8, 2020. The Bridge Loan had an interest rate of 10% per year, which began to accrue on the date of drawdown, and was computed based on the actual number of days elapsed based on a year of 365 days. The Bridge Loan holders have the same conversion rights as the 2020 Notes holders.

In connection with the closing of the Series C convertible preferred stock financing in December 2020, entities that are a part of Lilly Asia Ventures (LAV) agreed to effectively convert the Bridge Loan into shares of Series C preferred stock on the same terms as the 2020 Notes. The conversion was to be based on an outstanding loan balance equal to $1.9 million, consisting of (i) the principal loan amount ($1.8 million) plus (ii) accrued interest through December 29, 2020 ($0.1 million).

To help facilitate the transfer of cash from China to the United States to effectively convert the Bridge Loan, the Company and Terns China agreed to enter into an agreement with LAV to (i) repay the Bridge Loan and (ii) issue shares of Series C convertible preferred stock at the initial closing of the Series C financing to entities that are a part of LAV in exchange for a promissory note issued to the Company by LAV, or the LAV Affiliate Promissory Note.

The Bridge Loan was repaid in full by the Company following the requisite government approvals in China. Proceeds from the repayment of the Bridge Loan by Terns China were used by LAV to repay the LAV Affiliate Promissory Note in full. The fair value of the Bridge Loan was determined to be $2.1 million as of December 31, 2020. The Bridge Loan and the LAV Affiliate Promissory Note were paid in full in March 2021.

LAV Series A and Series B Promissory Notes

In November 2020, the Chinese government provided approval for entities affiliated with LAV to exercise the LAV Option (see Note 5, Convertible Preferred Stock). Terns Hong Kong agreed to repurchase all equity interests held by the LAV PRC Entities with proceeds to be used by LAV to purchase shares of Series A convertible preferred stock and Series B convertible preferred stock of the Company (Repurchase).

In December 2020, the Company issued 767,857 shares of Series A convertible preferred stock and 216,450 shares of Series B convertible preferred stock to an affiliate of LAV (LAV Affiliate) in exchange for a promissory note with a principal amount equal to the original investment by LAV in Terns China (LAV Series A and Series B Promissory Note). The LAV Series A and Series B Promissory Note was repaid through proceeds of the Repurchase which was completed in January 2021.

Prior to their repayment, the carrying value of the LAV Series A and Series B Promissory Notes approximated their respective fair value due to the short-term nature of the liability.

The outstanding LAV Series A and Series B Promissory Note was settled in January 2021 and was paid with the proceeds received from the note receivable of $10.8 million. The outstanding Bridge Loan was settled in March

2021 and was substantially paid with the proceeds received from the LAV Affiliate Promissory Note receivable of $1.9 million.

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (h)
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1I
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (d)
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 20
-Section 50
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495334-112611

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

+ Details

Convertible Preferred Stock

12 Months Ended

Dec. 31, 2022

Convertible Preferred Stock [Abstract]

Convertible Preferred Stock

All shares of preferred stock described below were converted into 16,079,230 shares of the Company’s common stock at the time of the IPO in February 2021.

Series A Preferred Stock

In April 2017, the Company entered into a Series A convertible preferred stock purchase agreement (Series A Agreement) whereby the Company issued 2,089,285 shares of Series A convertible preferred stock at $10.50 per share for an aggregate purchase price of $21.9 million.

Terns China received an aggregate $8.0 million from the LAV PRC Entities in connection with the Series A financing, which was presented as a noncontrolling interest. In connection with the Series A Agreement and this Terns China investment, the Company also issued an option to the LAV PRC Entities to convert their interest in the China Subsidiaries into an interest in Terns Cayman (the LAV Option).

Series B Preferred Stock

In October 2018, the Company entered into a Series B convertible preferred share purchase agreement (Series B Agreement), whereby the Company issued an aggregate of 2,384,195 shares of Series B convertible preferred stock at $30.80 per share for an aggregate purchase price of $73.4 million.

Terns China received $6.7 million from the LAV PRC Entities in connection with the Series B financing, which was presented as a noncontrolling interest. In connection with the Series B Agreement and this Terns China investment, the LAV Option was to allow the LAV PRC Entities to convert this interest in the China Subsidiaries into an interest in Terns Cayman.

LAV Series A and Series B Preferred Stock Options

In November 2020, the Chinese government provided approval for entities affiliated with Lilly Asia Ventures (LAV) to exercise the LAV Option. Terns Hong Kong agreed to repurchase all equity interests held by the LAV PRC Entities with proceeds to be used by LAV to purchase shares of Series A convertible preferred stock and Series B convertible preferred stock of the Company (Repurchase).

Series C Preferred Stock

In December 2020, the Company entered into a Series C preferred stock purchase agreement (Series C Convertible Preferred Stock Financing) whereby it issued an aggregate of 7,500,665 shares of Series C convertible preferred stock at $11.65 per share for gross proceeds of $87.4 million, which includes shares issued upon conversion of the 2020 Notes.

In connection with the Series C Convertible Preferred Stock Financing, the 2020 Notes, totaling unpaid principal and accrued interest of $15.9 million, converted into 1,366,820 shares of Series C convertible preferred stock. Furthermore, in December 2020, as part of the effective conversion of the Bridge Loan, the Company issued LAV an aggregate of 167,159 shares of Series C convertible preferred stock.

Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock are collectively referred to as “convertible preferred stock.”

In connection with the IPO, all the outstanding shares of convertible preferred stock converted into common stock and the Company does not have any shares of preferred stock outstanding as of December 31, 2022.

Common Stock and Stock-Based Compensation

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Common Stock and Stock-Based Compensation

As of each balance sheet date, the Company had reserved shares of common stock for issuance in connection with the following:


	December 31,
	2022		2021
Options outstanding under incentive award plans		4,823,928		3,577,485
Unvested restricted stock units		128,280		—
Shares available for future grant under incentive award plans		1,107,362		1,138,622
Shares available for future grant under employee stock purchase plans		323,920		240,000
Shares available for future grant under employment inducement award plans		1,310,000		—
Pre-funded warrants		14,630,000		—
Total shares reserved		22,323,490		4,956,107

Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends, if any, as may be declared by the Company’s board of directors, subject to the preferential dividend rights of the convertible preferred stock. Through December 31, 2022, no cash dividends have been declared or paid by the Company.

Stock-Based Compensation Plans

The Company has three stock-based compensation plans, the 2017 Incentive Award Plan (the “2017 Plan”), the 2021 Incentive Award Plan (the “2021 Plan”) and the 2022 Employment Inducement Award Plan (the “2022 Inducement Plan”). Although awards made under the 2017 Plan continue to be governed by its terms, the 2017 Plan was terminated at the time of our IPO and no further awards are made under this plan. The 2021 Plan, while effective, authorizes the granting of equity awards to employees and directors of the Company, as well as non-employee consultants. The 2022 Inducement Plan authorizes the granting of equity awards to newly hired employees of the Company. Stock options granted to employees and nonemployees under the plans generally vest over four years and allow the holder of the option to purchase common stock at a stated exercise price. Options granted under the plans generally expire ten years after the date of grant. The Company recognizes the stock-based compensation expense over the requisite service period of the individual grantees, which generally equals the vesting period.

2021 Incentive Award Plan

In January 2021, the Company's board of directors approved the 2021 Plan which permits the granting of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance bonus awards, performance stock unit awards and other stock awards to employees, directors, officers and consultants. In February 2021, 2,400,007 shares were authorized for issuance under the 2021 Plan, which shall be cumulatively increased on the first day of each year beginning in 2022 and ending in 2031 equal to the lesser of (i) the amount equal to 5% of the number of shares issued and outstanding on the last day of the immediately preceding fiscal year or (ii) such lower number of shares as may be determined by the Company’s board of directors. The 2021 Plan is the successor to the 2017 Incentive Award Plan and no additional awards may be issued from the 2017 Plan. However, the 2017 Plan will continue to govern the terms and conditions of the outstanding awards granted under this plan. Shares of common stock subject to awards granted under the 2017 Plan that are forfeited or lapse unexercised and which following the effective date of the 2021 Plan are not issued under the 2017 Plan will be available for issuance under the 2021 Plan. As of December 31, 2022, 1,107,362 shares of the Company’s common stock were available for future grants under the 2021 Plan. The number of authorized shares reserved for issuance under the 2021 Plan was increased by 2,686,158 shares effective as of January 1, 2023.

2021 Employee Stock Purchase Plan

The 2021 Employee Stock Purchase Plan (the “2021 ESPP”) was approved by the Company’s board of directors in January 2021. In February 2021, a total of 240,000 shares were initially reserved for issuance under this plan, which shall be cumulatively increased on the first day of each year beginning in 2022 and ending in 2031 equal to the lesser of (i) 1% of the shares outstanding (on an as converted basis) on the last day of the immediately preceding fiscal year and (ii) such number of shares as may be determined by the Company’s board of directors. As of December 31, 2022, 323,920 shares of the Company’s common stock were available for future grants under the 2021 ESPP. The number of authorized shares reserved for issuance under the 2021 ESPP was increased by 537,231 shares effective as of January 1, 2023.

Under the ESPP, eligible employees may select a rate of payroll deduction up to 15% of their eligible compensation subject to certain maximum purchase limitations. The duration for each offering period is 12 months and is divided into two purchase periods of approximately six months in length. Offerings are concurrent. The purchase price of the shares under the offering is the lesser of 85% of the fair market value of the shares on the offering date or 85% of the fair market value of the shares on the purchase date. A one-year look-back feature in the ESPP causes the offering period to automatically reset if the fair value of the Company’s common stock on the last day of the purchase period is less than that on the original offering date. ESPP purchases by employees are settled with newly-issued common stock from the ESPP’s previously authorized and available pool of shares.

As of December 31, 2022, there was $0.2 million of unrecognized stock-based compensation expense related to unvested employee stock purchases. The unrecognized stock-based compensation expense is estimated to be recognized over a period of 1.53 years as of December 31, 2022. There were 168,772 shares purchased by employees under the ESPP during the year ended December 31, 2022.

2022 Employment Inducement Award Plan

In September 2022, the Company's compensation committee approved the 2022 Employment Inducement Award Plan (the "2022 Inducement Plan"), which authorized 1,400,000 shares of common stock to be issued and permits the granting of nonqualified stock options, stock appreciation rights, restricted stock awards and restricted stock unit awards to newly hired employees and officers. As of December 31, 2022, 1,310,000 shares of the Company's common stock were available for future grants under the 2022 Inducement Plan.

Pre-Funded Warrants

In connection with the August 2022 Financing, the Company sold pre-funded warrants to purchase 14,630,000 shares of common stock at a price of $2.4199 per pre-funded warrant. The purchase price per share of each pre-funded warrant represents the per share offering price for the common stock, minus the $0.0001 per share exercise price of such pre-funded warrant. No pre-funded warrants have been exercised as of December 31, 2022.

Stock Options

The following table summarizes the stock option activity for all stock plans during the years ended December 31, 2022 and 2021:


	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term		Aggregate Intrinsic Value
						(in years)		(in thousands)
Outstanding as of December 31, 2020		2,466,670		$	8.03		9.61	$	21,678
Granted		1,429,850			11.83
Exercised		(156,104	)		5.86				858
Forfeited		(162,931	)		8.28
Outstanding as of December 31, 2021		3,577,485		$	9.72		9.09	$	491
Granted		1,405,020			4.44
Exercised		(10,000	)		0.00				21
Forfeited		(148,577	)		9.29
Outstanding as of December 31, 2022		4,823,928		$	8.22		8.46	$	11,721
Exercisable, December 31, 2022		2,537,942		$	9.14		7.97	$	3,664
Vested and expected to vest, December 31, 2022		4,823,928		$	8.22		8.46	$	11,721

The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock.

As of December 31, 2022 and 2021, there was $21.2 million and $28.6 million, respectively, of unrecognized stock-based compensation expense related to unvested stock options. The unrecognized stock-based compensation expense is estimated to be recognized over a period of 2.19 years as of December 31, 2022.

The total fair value of options vested during the year ended December 31, 2022 and 2021 was $10.9 million and $7.8 million, respectively.

Restricted Stock

Restricted stock units ("RSUs") granted to employees under the plans generally vest over four years. The number of shares issued on the date the RSUs vest is net of the minimum statutory tax withholdings, which are paid in cash to the appropriate taxing authorities on behalf of the Company’s employees. The Company recognizes the stock-based compensation expense over the requisite service period of the individual grantees, which generally equals the vesting period.

The following table summarizes the RSU activity for all stock plans during the years ended December 31, 2022 and 2021:


	Number of Shares			Weighted Average Grant-Date Fair Value
Unvested restricted common stock as of December 31, 2020		83,334		$	1.96
Vested		(71,429	)		1.96
Forfeited		(11,905	)		1.96
Unvested restricted common stock as of December 31, 2021		—		$	—
Granted		147,750			3.99
Forfeited		(19,470	)		3.37
Unvested restricted common stock as of December 31, 2022		128,280		$	4.09

As of December 31, 2022, there was $0.4 million of unrecognized stock-based compensation expense related to restricted stock which is estimated to be recognized over a period of 3.46 years. As of December 31, 2021, there was no unrecognized stock-based compensation expense related to restricted stock granted by the Company.

No restricted stock vested during the year ended December 31, 2022. The total fair value of restricted stock vested during the year ended December 31, 2021 was $0.1 million.

Stock-Based Compensation Expense

The Company estimated the fair value of options granted and rights to acquire stock granted under the Company’s employee stock purchase plan using a Black-Scholes option pricing model with the following assumptions presented on a weighted average basis:


	Year Ended December 31,
	2022			2021
Stock Option Plans
Expected term (years)		5.99			6.03
Expected volatility		72.67	%		76.60	%
Risk-free interest rate		2.29	%		1.12	%
Fair value of underlying common stock	$	4.44		$	11.83
Weighted average grant-date fair value per share	$	2.91		$	7.82
Employee Stock Purchase Plans
Expected term (years)		0.89			0.75
Expected volatility		70.08	%		60.82	%
Risk-free interest rate		2.55	%		0.17	%
Fair value of underlying common stock	$	2.95		$	6.53
Weighted average grant-date fair value per share	$	1.25		$	2.33

Stock-based compensation expense was classified in the consolidated statements of operations and comprehensive loss as follows:


	Year Ended December 31,
(in thousands)	2022		2021
Research and development expense	$	3,025	$	2,055
General and administrative expense		7,743		6,091
Total stock-based compensation expense	$	10,768	$	8,146

Income Tax

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Income Tax

The following table presents domestic and foreign components of loss before income taxes:


	Year Ended December 31,
(in thousands)	2022			2021
U.S.	$	(60,226	)	$	(49,733	)
Foreign		239			83
Total loss before income tax	$	(59,987	)	$	(49,650	)

The following table presents the provision for income taxes:


	Year Ended December 31,
(in thousands)	2022		2021
Current
Federal	$	—	$	105
State		5		1
Foreign		299		313
Total current	$	304	$	419
Deferred
Foreign	$	54	$	89
Total deferred	$	54	$	89
Total income tax expense	$	358	$	508

The reconciliation of the U.S. federal statutory income tax benefit to the Company’s effective income tax rate is as follows:


	Year Ended December 31,
	2022			2021
Tax benefit at U.S. statutory rate		21.00	%		21.00	%
State income taxes, net of Federal tax benefit		(0.01	)		—
Foreign income taxed at non-U.S. rates		(0.02	)		(0.37	)
Domestication		—			32.57
Other permanent items		(0.11	)		(0.04	)
Stock-based compensation		(0.47	)		(0.52	)
Research and development credits		3.00			2.14
Unrecognized tax benefit		(0.57	)		(1.18	)
Global intangible low-taxed income		(1.09	)		(0.04	)
Increase in valuation allowance		(21.93	)		(54.53	)
Other		(0.40	)		(0.05	)
		(0.60	)%		(1.02	)%

The difference between the provision for income taxes and the income tax determined by applying the statutory federal income tax rate of 21% was primarily due to the change in valuation allowance.

Significant components of the Company’s deferred tax assets and liabilities are as follows:


	As of December 31,
(in thousands)	2022			2021
Deferred tax assets:
Accruals and reserves	$	820		$	575
Intangibles		12,929			14,574
Stock-based compensation		3,549			1,582
Net operating loss		13,841			10,271
Research and development credits		3,650			1,930
Lease liability		241			—
Capitalized research and development		7,410			—
Other		61			87
Valuation allowance		(42,207	)		(28,849	)
Total deferred tax assets	$	294		$	170
Deferred tax liabilities:
Fixed assets	$	(50	)	$	(78	)
Operating lease assets		(207	)		—
Total deferred tax liabilities	$	(257	)	$	(78	)
Net deferred tax assets	$	37		$	92

As of December 31, 2022, the Company recorded a full valuation allowance against its U.S. net deferred tax assets as it believes these deferred tax assets were not realizable on a more likely than not basis. This is based upon the weight of available evidence, including historical operating performance, the change of structure due to the Domestication, and that a net loss will be expected to occur in the foreseeable future.

As of December 31, 2022, the Company had federal and state net operating loss carryforwards of approximately $65.8 million and $0.7 million, respectively. The federal net operating loss has an indefinite carryforward while the state net operating loss will begin to expire in 2042. As of December 31, 2021, the Company had federal and state net operating loss carryforwards of approximately $48.7 million and $0.4 million, respectively.

As of December 31, 2022 and 2021, the Company had federal Research & Development (R&D) credit carryforwards of approximately $4.1 million and $1.9 million, respectively, which will begin to expire in 2039. As of December 31, 2022 and 2021, the Company had California R&D credit carryforwards of approximately $2.0 million and $1.7 million, respectively, which do not expire.

Utilization of net operating loss carryforwards and credits may be subject to a substantial annual limitation due to the ownership change limitations provided by the Internal Revenue Code of 1986, as amended, and similar state provisions. The annual limitation may result in the expiration of net operating losses and credits before utilization. The Company does not expect any previous ownership changes, as defined under Section 382 and 383 of the Internal Revenue Code, to result in a limitation that will materially reduce the total amount of net operating loss carryforwards and credits that can be utilized. Further, foreign loss carryforwards maybe subject to limitations under the applicable laws of the taxing jurisdictions due to ownership change limitations.

Beginning in 2022, the newly enacted tax legislation required U.S. R&D expenditures to be capitalized and amortized ratably over a five-year period. Expenditures attributed to research conducted outside of the U.S. must be capitalized and amortized over a 15-year period. The Company estimated the costs incurred and required to be capitalized in 2022 based upon the current year R&D expenses and adjusted for book to tax basis differences.

As of December 31, 2022, the Company has provided U.S. income taxes on all its foreign earnings. The Company continues to permanently reinvest the cash held offshore to support its working capital needs. Accordingly, no additional foreign withholding taxes that may be required from certain jurisdictions in the event of a cash distribution have been provided for.

As of December 31, 2022 and 2021, the total amount of unrecognized tax benefits was $6.3 million and $5.8 million, respectively, $4.2 million and $4.5 million of which would affect income tax expense, if recognized, before consideration of any valuation allowance. The Company does not expect the unrecognized tax benefits to change significantly over the next 12 months.

A reconciliation of the beginning and ending unrecognized tax benefit are as follows:


	Year Ended December 31,
(in thousands)	2022			2021
Unrecognized tax benefit at beginning of year	$	5,849		$	5,406
Increases related to prior year tax positions		150			365
Increases related to current year tax positions		706			451
Decreases related to prior year tax positions		(389	)		(373	)
Unrecognized tax benefit at end of year	$	6,316		$	5,849

The Company includes interest and penalties related to unrecognized tax benefits within the provision for income taxes. As of December 31, 2022 and 2021, the total amount of gross interest and penalties accrued was $0.3 million and $0.1 million, respectively.

The Company is subject to income taxes in the U.S. federal, state and various foreign jurisdictions. Tax regulations within each jurisdiction are subject to the interpretation of the related tax laws and regulations and require significant judgment to apply. The Company’s tax years remain open for examination by all tax authorities since inception as well as carryover attributes beginning December 31, 2019, remain open to adjustment by the U.S. and foreign authorities.

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330215-122817

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 17
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32809-109319

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 14
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32705-109319

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 270
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=6424409&loc=d3e44925-109338

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-URI https://asc.fasb.org/topic&trid=2144680

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Assignment, License and Collaboration Agreements

12 Months Ended

Dec. 31, 2022

Assignment License And Collaboration Agreements [Abstract]

Assignment, License and Collaboration Agreements

License Agreements

TERN-101 License Agreement with Eli Lilly

In February 2018, the Company entered a worldwide exclusive license agreement with Eli Lilly and Company (Lilly) (Lilly FXR 2018 License Agreement). Under the terms of the Lilly FXR 2018 License Agreement, Lilly granted the Company an exclusive, royalty-bearing license to make, have made, use, offer for sale, sell, import and have imported, including all rights to develop, manufacture and commercialize covered products in the field in the territory and a sublicensing right that allows the Company to grant sublicenses to affiliates and third parties to perform any portion of the development, manufacture and commercialization of covered products. The Company is required to use commercially reasonable efforts to meet development event milestones, develop the covered product in the field in mainland China and commercialize the covered product in the field in mainland China.

The Company agreed to pay Lilly up to an aggregate of $6.0 million in pre-specified development milestones for the first covered product in mainland China, and up to an aggregate of $50.0 million in pre-specified development milestones for the first covered product in ex-mainland China. The Company also agreed to pay Lilly tiered royalties calculated on a calendar year basis, in the mid-single digits to low teens on net sales ranging from the low hundreds of millions of dollars to the low billions of dollars. The Lilly FXR 2018 License Agreement expires upon expiry of the last remaining royalty obligation for a licensed product. As of December 31, 2022, the Company has not paid any amounts under the agreement and no milestones have been achieved. The Company has not recorded any research and development expense during the years ended December 31, 2022 and 2021 related to this agreement.

TERN-201 License Agreement with Eli Lilly

In March 2018, the Company entered into an exclusive license agreement with Lilly (Lilly VAP-1 2018 License Agreement). Under the terms of the Lilly VAP-1 2018 License Agreement, Lilly granted the Company an exclusive, royalty-bearing license to make, have made, use, offer for sale, sell, import and have imported, including all rights to develop, manufacture and commercialize covered products and a sublicensing right that allows the Company to grant sublicenses to affiliates and third parties to perform any portion of the development, manufacture and commercialization of covered products. The Company will remain directly responsible for all amounts owed to Lilly, regardless of sublicenses. The Company is required to use commercially reasonable efforts to meet development events according to achievement due dates and commercialize the covered product in the field in the major markets.

The Company paid Lilly a non-refundable, non-creditable upfront payment of $4.0 million, which was recorded as research and development expense in the Company’s statement of operations and comprehensive loss for the year ended December 31, 2018. In addition, pursuant to the terms of the Lilly VAP-1 2018 License Agreement, the Company agreed to pay Lilly up to an aggregate of $74.0 million in pre-specified development milestones for the first covered product, and up to an aggregate of $30.0 million in pre-specified development milestones for the second indication of a covered product. The Company must also pay Lilly tiered royalties calculated on a calendar year basis, in the mid-single digits to mid-teens on net sales ranging from the high tens of millions of dollars to the low billions of dollars. The Lilly VAP-1 2018 License Agreement expires upon expiry of the last remaining royalty obligation for a licensed product. As of December 31, 2022, the Company has paid $4.0 million to Lilly. No development milestones have been met as of December 31, 2022. The Company has not recorded any research and development expense during the years ended December 31, 2022 and 2021 related to this agreement.

Assignment Agreement

In June 2019, the Company entered into an assignment agreement with Vintagence Biotechnology Ltd. (Vintagence) (Vintagence 2019 Assignment Agreement). Under the terms of the Vintagence 2019 Assignment Agreement, Vintagence assigned and agreed to assign to the Company any and all worldwide rights, title and interest in and to the Vintagence technology and gave Terns a sublicensing right that allows the Company to grant sublicenses to any of its affiliates and/or to licensees or contractors to perform any portion of the development, manufacture, and/or commercialization of covered compounds or covered products. The Company will remain directly responsible for all amounts owed to Vintagence under this agreement, regardless of sublicenses. The Company is required to use commercially reasonable efforts to commercialize the covered product in the field in the major markets.

The Company paid Vintagence a non-refundable, non-creditable upfront payment of $0.7 million, which was recorded as research and development expense in the Company’s statements of operations and comprehensive loss for the year ended December 31, 2019. In addition, pursuant to the terms of the Vintagence 2019 Assignment Agreement, the Company agreed to pay Vintagence up to CNY 205.0 million in development milestones for the first covered product. The term of the Vintagence 2019 Assignment Agreement will continue in effect on a country-by-country basis until all milestone payments are made. The Company has the right to terminate the agreement in its entirety or on a covered product-by-covered product and country-by-country basis, in its sole discretion by giving 60 days advance written notice to Vintagence. As of December 31, 2022, the Company has paid $4.4 million to Vintagence which includes a milestone payment of $1.5 million in connection with the Company's IND filing for TERN-501 in December 2020 and a milestone payment of $2.2 million in connection with the initiation of dosing in the Phase 2a DUET trial in July 2022. The Company has recognized research and development expense of $2.2 million during the year ended December 31, 2022 related to this agreement. The Company has not recognized any research and development expenses during the year ended December 31, 2021 related to this agreement.

Hansoh Option and License Agreement

In July 2020, the Company entered into an exclusive option and license agreement with Hansoh (Shanghai) Healthtech Co., Ltd. (Hansoh Healthtech) and Jiangsu Hansoh Pharmaceutical Group Company Ltd. (Jiangsu Hansoh) (collectively, Hansoh) (Hansoh 2020 Option and License Agreement). Under the terms of the Hansoh 2020 Option and License Agreement, the Company granted Hansoh an exclusive, non-transferable, non-sublicensable, fully-paid, royalty-free license to conduct preliminary studies on the licensed compound (TERN-701, formerly known as TRN-000632) with an option to exclusively license the same for development and commercialization of licensed products in all prophylactic, palliative, therapeutic and/or diagnostic uses in connection with all human diseases and disorders (including development and research activities on animal models thereof) in the field of oncology, including all types of cancers (Field) in mainland China, Taiwan, Hong Kong and Macau (collectively, the Territory). In November 2021, Hansoh exercised its option and was granted an exclusive, royalty-bearing license, with the right to sublicense to exploit licensed compound and licensed products in the Field and in the Territory.

Under the Hansoh 2020 Option and License Agreement, Hansoh was required to pay the Company a refundable, non-creditable upfront payment. The Company received an upfront payment of $0.8 million during the year ended December 31, 2020, which was recognized as a refund liability and presented within accrued expenses and other current liabilities on the consolidated balance sheets as of December 31, 2020. In connection with Hansoh’s exercise of its option in November 2021, the Company recognized $1.0 million in license fee revenue within the consolidated statements of operations and comprehensive loss during the year ended December 31, 2021.

In addition, pursuant to the Hansoh 2020 Option and License Agreement, Hansoh has agreed to pay the Company up to $67.0 million in pre-specified clinical, regulatory and sales milestones. Hansoh must also pay the Company royalties in the mid-single digits based on net sales of all licensed products. The term of the Hansoh 2020 Option and License Agreement will continue until the end of the last-to-expire royalty term. As of December 31, 2022, no milestones have been met and future payments are all constrained.

Nature of the Business, Basis of Presentation and Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Basis of Presentation

Initial Public Offering

At-the-Market Offering

August 2022 Financing

December 2022 Financing

Certificate of Incorporation

Reverse Stock Split

Impact of the COVID-19 Pandemic

Revenue Recognition

Licenses of intellectual property

Milestone payments

Commercial milestones and royalties

Use of Estimates

Cash, Cash Equivalents, Restricted Cash and Marketable Securities

Cash, Cash Equivalents and Marketable Securities

The fair value and amortized cost of marketable securities by major security type is as follows:


	December 31, 2022
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	23,029	$	—	$	—		$	23,029
U.S. government securities		44,555		31		(383	)		44,203
Non-U.S. government securities		3,024		—		(16	)		3,008
Corporate debt securities		36,411		—		(146	)		36,265
Commercial paper		56,403		—		—			56,403
Total	$	163,422	$	31	$	(545	)	$	162,908

Classified as:
Cash equivalents								$	23,029
Marketable securities									139,879
Total								$	162,908

	December 31, 2021
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	33,239	$	—	$	—		$	33,239
U.S. government securities		36,322		—		(130	)		36,192
Non-U.S. government securities		11,194		—		(12	)		11,182
Corporate debt securities		39,495		—		(52	)		39,443
Commercial paper		31,466		—		—			31,466
Total	$	151,716	$	—	$	(194	)	$	151,522

Classified as:
Cash equivalents								$	33,239
Marketable securities									118,283
Total								$	151,522

Operating Leases and Rent Expense

Classification of Convertible Preferred Stock

Research and Development Expenses

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities included the following:


	December 31,
(in thousands)	2022		2021
Research and development costs	$	1,209	$	1,570
Accrued professional fees		925		363
Compensation and benefit costs		3,843		2,403
Other		185		358
Total accrued expenses and other current liabilities	$	6,162	$	4,694

Income Taxes

Comprehensive Loss

Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources.

Stock-Based Compensation

Net Loss Per Share of Common Stock


	December 31,
	2022		2021
Options to purchase common stock		4,823,928		3,577,485
Unvested restricted stock units		128,280		—
Shares issuable under employee stock purchase plan		25,326		6,717
Total		4,977,534		3,584,202

Deferred Offering Costs

Property and Equipment

Property and equipment, net consisted of the following:


		December 31,
(in thousands)	Estimated Useful Lives	2022			2021
Leasehold improvements	Shorter of remaining life of lease or useful life of asset	$	758		$	928
Furniture and fixtures	5 years		294			281
Computer equipment	3 years		203			202
Office equipment	5 years		146			102
Lab equipment	3 to 5 years		758			718
Property and equipment, gross			2,159			2,231
Less: Accumulated depreciation			(1,402	)		(1,185	)
Total property and equipment, net		$	757		$	1,046

The Company recognized depreciation expense related to these assets of $0.5 million during each of the years ended December 31, 2022 and 2021.

Impairment of Long-Lived Assets

Functional Currencies and Foreign Currency Translation

Concentration of Credit Risk

Patent Costs

Commitments and Contingencies

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements Not Yet Adopted

Nature of the Business, Basis of Presentation and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Schedule of Fair Value And Amortized Cost of Marketable Securities

The fair value and amortized cost of marketable securities by major security type is as follows:


	December 31, 2022
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	23,029	$	—	$	—		$	23,029
U.S. government securities		44,555		31		(383	)		44,203
Non-U.S. government securities		3,024		—		(16	)		3,008
Corporate debt securities		36,411		—		(146	)		36,265
Commercial paper		56,403		—		—			56,403
Total	$	163,422	$	31	$	(545	)	$	162,908

Classified as:
Cash equivalents								$	23,029
Marketable securities									139,879
Total								$	162,908

	December 31, 2021
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	33,239	$	—	$	—		$	33,239
U.S. government securities		36,322		—		(130	)		36,192
Non-U.S. government securities		11,194		—		(12	)		11,182
Corporate debt securities		39,495		—		(52	)		39,443
Commercial paper		31,466		—		—			31,466
Total	$	151,716	$	—	$	(194	)	$	151,522

Classified as:
Cash equivalents								$	33,239
Marketable securities									118,283
Total								$	151,522

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities included the following:


	December 31,
(in thousands)	2022		2021
Research and development costs	$	1,209	$	1,570
Accrued professional fees		925		363
Compensation and benefit costs		3,843		2,403
Other		185		358
Total accrued expenses and other current liabilities	$	6,162	$	4,694

Schedule of Antidilutive Securities Excluded from Computation of Net Loss per Share

The Company excluded the following potential shares of common stock, presented based on amounts outstanding at each period end, from the computation of diluted net loss attributable to common stockholders per share of common stock for the periods indicated because including them would have had an anti-dilutive effect:


	December 31,
	2022		2021
Options to purchase common stock		4,823,928		3,577,485
Unvested restricted stock units		128,280		—
Shares issuable under employee stock purchase plan		25,326		6,717
Total		4,977,534		3,584,202

Schedule of Property and Equipment

Property and equipment, net consisted of the following:


		December 31,
(in thousands)	Estimated Useful Lives	2022			2021
Leasehold improvements	Shorter of remaining life of lease or useful life of asset	$	758		$	928
Furniture and fixtures	5 years		294			281
Computer equipment	3 years		203			202
Office equipment	5 years		146			102
Lab equipment	3 to 5 years		758			718
Property and equipment, gross			2,159			2,231
Less: Accumulated depreciation			(1,402	)		(1,185	)
Total property and equipment, net		$	757		$	1,046

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Schedule of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis:


	As of December 31, 2022:
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents
Cash in bank balances	$	120,206	$	—	$	—	$	120,206
Money market funds		23,029		—		—		23,029
Total cash and equivalents	$	143,235	$	—	$	—	$	143,235
Marketable securities
U.S. government securities	$	—	$	44,203	$	—	$	44,203
Non-U.S. government securities		—		3,008		—		3,008
Corporate debt securities		—		36,265		—		36,265
Commercial paper		—		56,403		—		56,403
Total marketable securities	$	—	$	139,879	$	—	$	139,879

	As of December 31, 2021:
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents
Cash in bank balances	$	14,460	$	—	$	—	$	14,460
Money market funds		33,239		—		—		33,239
Total cash and equivalents	$	47,699	$	—	$	—	$	47,699
Marketable securities
U.S. government securities	$	—	$	36,192	$	—	$	36,192
Non-U.S. government securities		—		11,182		—		11,182
Corporate debt securities		—		39,443		—		39,443
Commercial paper		—		31,466		—		31,466
Total marketable securities	$	—	$	118,283	$	—	$	118,283

The aggregate amortized cost and fair value of marketable securities

Schedule of Aggregate Amortized Cost and Fair Value of Marketable Securities

as of December 31, 2022, by contractual maturity, are as follows:


(in thousands)	Amortized Cost		Fair Value
Due in one year or less	$	136,501	$	136,008
Due after one year through two years		3,892		3,871
Total marketable securities	$	140,393	$	139,879

Leases (Tables)

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

Schedule of components of lease cost

Components of lease cost are as follows:


	Year Ended
(in thousands)	December 31, 2022
Operating lease cost	$	610
Short-term cost		43
Total lease cost	$	653

Weighted-average remaining lease term		1.79
Weighted-average discount rate		6.00	%

Schedule of future minimum lease payments required under operating leases

The Company's future minimum lease payments are as follows:


(in thousands)	Operating Leases
2023	$	850
2024		559
2025 and thereafter		—
Total lease payments		1,409
Less: Imputed interest		(204	)
Present value of lease liabilities		1,205
Less: Current portion of lease liabilities		(661	)
Total lease liabilities, non-current	$	544

Schedule of future minimum lease payments required under operating leases

The future minimum annual lease payments required under the Company’s existing operating lease agreements as of December 31, 2021 prior to the adoption of ASC 842 were as follows:


(in thousands)	Operating Leases
2022	$	669
2023		652
2024		559
2025 and thereafter		—
Total	$	1,880

Common Stock and Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Common Stock Shares Reserved for Issuance

As of each balance sheet date, the Company had reserved shares of common stock for issuance in connection with the following:


	December 31,
	2022		2021
Options outstanding under incentive award plans		4,823,928		3,577,485
Unvested restricted stock units		128,280		—
Shares available for future grant under incentive award plans		1,107,362		1,138,622
Shares available for future grant under employee stock purchase plans		323,920		240,000
Shares available for future grant under employment inducement award plans		1,310,000		—
Pre-funded warrants		14,630,000		—
Total shares reserved		22,323,490		4,956,107

Summary of Stock Option Activity

The following table summarizes the stock option activity for all stock plans during the years ended December 31, 2022 and 2021:


	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term		Aggregate Intrinsic Value
						(in years)		(in thousands)
Outstanding as of December 31, 2020		2,466,670		$	8.03		9.61	$	21,678
Granted		1,429,850			11.83
Exercised		(156,104	)		5.86				858
Forfeited		(162,931	)		8.28
Outstanding as of December 31, 2021		3,577,485		$	9.72		9.09	$	491
Granted		1,405,020			4.44
Exercised		(10,000	)		0.00				21
Forfeited		(148,577	)		9.29
Outstanding as of December 31, 2022		4,823,928		$	8.22		8.46	$	11,721
Exercisable, December 31, 2022		2,537,942		$	9.14		7.97	$	3,664
Vested and expected to vest, December 31, 2022		4,823,928		$	8.22		8.46	$	11,721

Schedule of Stock Options Weighted Average Assumptions


	Year Ended December 31,
	2022			2021
Stock Option Plans
Expected term (years)		5.99			6.03
Expected volatility		72.67	%		76.60	%
Risk-free interest rate		2.29	%		1.12	%
Fair value of underlying common stock	$	4.44		$	11.83
Weighted average grant-date fair value per share	$	2.91		$	7.82
Employee Stock Purchase Plans
Expected term (years)		0.89			0.75
Expected volatility		70.08	%		60.82	%
Risk-free interest rate		2.55	%		0.17	%
Fair value of underlying common stock	$	2.95		$	6.53
Weighted average grant-date fair value per share	$	1.25		$	2.33

Summary of Restricted Stock Award Activity

years ended December 31, 2022 and 2021:


	Number of Shares			Weighted Average Grant-Date Fair Value
Unvested restricted common stock as of December 31, 2020		83,334		$	1.96
Vested		(71,429	)		1.96
Forfeited		(11,905	)		1.96
Unvested restricted common stock as of December 31, 2021		—		$	—
Granted		147,750			3.99
Forfeited		(19,470	)		3.37
Unvested restricted common stock as of December 31, 2022		128,280		$	4.09

Schedule of Stock-based Compensation Expense

Stock-based compensation expense was classified in the consolidated statements of operations and comprehensive loss as follows:


	Year Ended December 31,
(in thousands)	2022		2021
Research and development expense	$	3,025	$	2,055
General and administrative expense		7,743		6,091
Total stock-based compensation expense	$	10,768	$	8,146

Income Tax (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Components of (Loss) Income Before Income Taxes

The following table presents domestic and foreign components of loss before income taxes:


	Year Ended December 31,
(in thousands)	2022			2021
U.S.	$	(60,226	)	$	(49,733	)
Foreign		239			83
Total loss before income tax	$	(59,987	)	$	(49,650	)

Schedule of Provision for Income Taxes

The following table presents the provision for income taxes:


	Year Ended December 31,
(in thousands)	2022		2021
Current
Federal	$	—	$	105
State		5		1
Foreign		299		313
Total current	$	304	$	419
Deferred
Foreign	$	54	$	89
Total deferred	$	54	$	89
Total income tax expense	$	358	$	508

Reconciliation between Effect of Applying Federal Statutory Rate and Effective Income Tax Rate

The reconciliation of the U.S. federal statutory income tax benefit to the Company’s effective income tax rate is as follows:


	Year Ended December 31,
	2022			2021
Tax benefit at U.S. statutory rate		21.00	%		21.00	%
State income taxes, net of Federal tax benefit		(0.01	)		—
Foreign income taxed at non-U.S. rates		(0.02	)		(0.37	)
Domestication		—			32.57
Other permanent items		(0.11	)		(0.04	)
Stock-based compensation		(0.47	)		(0.52	)
Research and development credits		3.00			2.14
Unrecognized tax benefit		(0.57	)		(1.18	)
Global intangible low-taxed income		(1.09	)		(0.04	)
Increase in valuation allowance		(21.93	)		(54.53	)
Other		(0.40	)		(0.05	)
		(0.60	)%		(1.02	)%

Components of Deferred Tax Assets and Liabilities

Significant components of the Company’s deferred tax assets and liabilities are as follows:


	As of December 31,
(in thousands)	2022			2021
Deferred tax assets:
Accruals and reserves	$	820		$	575
Intangibles		12,929			14,574
Stock-based compensation		3,549			1,582
Net operating loss		13,841			10,271
Research and development credits		3,650			1,930
Lease liability		241			—
Capitalized research and development		7,410			—
Other		61			87
Valuation allowance		(42,207	)		(28,849	)
Total deferred tax assets	$	294		$	170
Deferred tax liabilities:
Fixed assets	$	(50	)	$	(78	)
Operating lease assets		(207	)		—
Total deferred tax liabilities	$	(257	)	$	(78	)
Net deferred tax assets	$	37		$	92

Reconciliation of Unrecognized Tax Benefits

A reconciliation of the beginning and ending unrecognized tax benefit are as follows:


	Year Ended December 31,
(in thousands)	2022			2021
Unrecognized tax benefit at beginning of year	$	5,849		$	5,406
Increases related to prior year tax positions		150			365
Increases related to current year tax positions		706			451
Decreases related to prior year tax positions		(389	)		(373	)
Unrecognized tax benefit at end of year	$	6,316		$	5,849

Net Loss Per Share of Common Stock (Tables)

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Schedule of Antidilutive Securities Excluded from Computation of Net Loss per Share


	December 31,
	2022		2021
Options to purchase common stock		4,823,928		3,577,485
Unvested restricted stock units		128,280		—
Shares issuable under employee stock purchase plan		25,326		6,717
Total		4,977,534		3,584,202

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2022

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Lease Payments Due Under Operating Leases

The Company's future minimum lease payments are as follows:


(in thousands)	Operating Leases
2023	$	850
2024		559
2025 and thereafter		—
Total lease payments		1,409
Less: Imputed interest		(204	)
Present value of lease liabilities		1,205
Less: Current portion of lease liabilities		(661	)
Total lease liabilities, non-current	$	544

Nature of the Business, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, $ in Thousands	1 Months Ended				3 Months Ended	10 Months Ended	12 Months Ended
	Feb. 28, 2023 USD ($) shares	Dec. 31, 2022 USD ($) $ / shares shares	Aug. 31, 2022 USD ($) $ / shares shares	Feb. 28, 2021 USD ($) $ / shares shares	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 $ / shares shares	Oct. 31, 2018 $ / shares	Apr. 30, 2017 $ / shares
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Common stock, authorized		150,000,000		150,000,000		150,000,000	150,000,000	150,000,000	299,700,000
Common stock, par value \| $ / shares		$ 0.0001				$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, shares authorized				10,000,000
Preferred stock, par or stated value per share \| $ / shares				$ 0.0001
Description of reverse stock split								In January 2021, the Company filed an amended and restated certificate of incorporation to effectuate a reverse split of shares of the Company’s common stock and convertible preferred stock on a 1-for-14 basis (the “Reverse Stock Split”). The par value and the number of authorized shares of the convertible preferred stock and common stock were not adjusted as a result of the Reverse Stock Split. All issued and outstanding common stock, options to purchase common stock and per share amounts contained in the consolidated financial statements have been retroactively adjusted to give effect to the Reverse Stock Split for all periods presented.
Reverse stock split, conversion ratio								0.0714
Marketable securities \| $		$ 139,879				$ 139,879	$ 139,879
Recognized depreciation expense \| $							500	$ 500
Impairments of long-lived assets \| $							$ 0
Maximum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated Useful Lives							5 years
Minimum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated Useful Lives							3 years
ASU 2016-02
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]		false				false	false
Change in accounting principle, accounting standards update, adoption date		Jan. 01, 2022				Jan. 01, 2022	Jan. 01, 2022
Recognize additional operating liabilities \| $		$ 1,700				$ 1,700	$ 1,700
ROU assets \| $		$ 1,500				$ 1,500	$ 1,500
Series A convertible preferred stock
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Convertible preferred stock,authorized									40,000,000
Convertible preferred stock, par value \| $ / shares											$ 10.50
Series B convertible preferred stock
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Convertible preferred stock,authorized									36,409,088
Convertible preferred stock, par value \| $ / shares										$ 30.80
Series C convertible preferred stock
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Convertible preferred stock,authorized									111,619,996
Convertible preferred stock, par value \| $ / shares									$ 11.65
IPO
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of shares issued				8,625,000
Underwriters option to purchase additional shares				1,125,000
Net proceeds from issuance of common stock allocated to pre-funded warrants \| $				$ 133,000
Convertible preferred stock, shares issued upon conversion				16,079,230
August 2022 Financing
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of shares issued			12,250,000
Net proceeds from issuance of common stock allocated to pre-funded warrants \| $			$ 33,000
Pre-funded warrant price \| $ / shares			$ 2.4199
Shares issued, price per share \| $ / shares			$ 2.42
Pre-funded warrants to purchase			14,630,000
Aggregate net proceeds after deducting underwriting discounts and commissions and other offering expenses common stock \| $			$ 60,700
Common stock, par value \| $ / shares			$ 0.0001
December 2022 Financing
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of shares issued		10,350,000
Underwriters option to purchase additional shares		1,552,500
Net proceeds from issuance of common stock allocated to pre-funded warrants \| $		$ 80,800
Shares issued, price per share \| $ / shares		$ 7.25				$ 7.25	$ 7.25
At-the-Market Offering
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of shares issued						4,122,628
Net proceeds from issuance of common stock allocated to pre-funded warrants \| $						$ 24,900
Offer price \| $					$ 75,000
At-the-Market Offering \| Subsequent Event
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of shares issued	2,929,922
Net proceeds from issuance of common stock allocated to pre-funded warrants \| $	$ 27,900

Nature of the Business, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Fair Value And Amortized Cost of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	$ 163,422	$ 151,716
Unrealized Gains	31	0
Unrealized Losses	(545)	(194)
Fair Value	162,908	151,522
Cash equivalents	23,029	33,239
Marketable securities	139,879	118,283
Total	162,908	151,522
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	23,029	33,239
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	23,029	33,239
U.S. government securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	44,555	36,322
Unrealized Gains	31	0
Unrealized Losses	(383)	(130)
Fair Value	44,203	36,192
Non-U.S. Government Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	3,024	11,194
Unrealized Gains	0	0
Unrealized Losses	(16)	(12)
Fair Value	3,008	11,182
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	36,411	39,495
Unrealized Gains	0	0
Unrealized Losses	(146)	(52)
Fair Value	36,265	39,443
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	56,403	31,466
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	$ 56,403	$ 31,466

Nature of the Business, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Research and development costs	$ 1,209	$ 1,570
Accrued professional fees	925	363
Compensation and benefit costs	3,843	2,403
Other	185	358
Total accrued expenses and other current liabilities	$ 6,162	$ 4,694

Nature of the Business, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	4,977,534	3,584,202
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	4,823,928	3,577,485
Unvested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	128,280	0
Shares Issuable Under Employee Stock Purchase Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	25,326	6,717

Nature of the Business, Basis of Presentation and Summary of Significant Accounting Policies - Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 2,159	$ 2,231
Less : Accumulated depreciation	(1,402)	(1,185)
Property, Plant and Equipment, Net, Total	$ 757	1,046
Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	3 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 758	928
Estimated Useful Lives	Shorter of remaining life of lease or useful life of asset
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 294	281
Estimated Useful Lives	5 years
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 203	202
Estimated Useful Lives	3 years
Office equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 146	102
Estimated Useful Lives	5 years
Lab equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 758	$ 718
Lab equipment \| Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	3 years
Lab equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Assets:
Marketable securities	$ 139,879
Recurring
Assets:
Total cash and cash equivalents	143,235	$ 47,699
Marketable securities	139,879	118,283
Recurring \| Cash in bank balances
Assets:
Total cash and cash equivalents	120,206	14,460
Recurring \| Money Market Funds
Assets:
Total cash and cash equivalents	23,029	33,239
Recurring \| U.S. government securities
Assets:
Marketable securities	44,203	36,192
Recurring \| Non-U.S. Government Securities
Assets:
Marketable securities	3,008	11,182
Recurring \| Corporate Debt Securities
Assets:
Marketable securities	36,265	39,443
Recurring \| Commercial Paper
Assets:
Marketable securities	56,403	31,466
Recurring \| Level 1
Assets:
Total cash and cash equivalents	143,235	47,699
Recurring \| Level 1 \| Cash in bank balances
Assets:
Total cash and cash equivalents	120,206	14,460
Recurring \| Level 1 \| Money Market Funds
Assets:
Total cash and cash equivalents	23,029	33,239
Recurring \| Level 2
Assets:
Marketable securities	139,879	118,283
Recurring \| Level 2 \| U.S. government securities
Assets:
Marketable securities	44,203	36,192
Recurring \| Level 2 \| Non-U.S. Government Securities
Assets:
Marketable securities	3,008	11,182
Recurring \| Level 2 \| Corporate Debt Securities
Assets:
Marketable securities	36,265	39,443
Recurring \| Level 2 \| Commercial Paper
Assets:
Marketable securities	$ 56,403	$ 31,466

Fair Value Measurements -Schedule of Aggregate Amortized Cost and Fair Value of Marketable Securities (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Fair Value Disclosures [Abstract]
Due in one year or less	$ 136,008
Due after one year through two years	3,871
Total marketable securities	139,879
Due in one year or less	136,501
Due after one year through two years	3,892
Marketable Securities at Amortized Cost, Total	$ 140,393

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Assets, Transfers into Level 3	$ 0	$ 0
Assets, Transfers out of Level 3	0
Liabilities, Transfers into Level 3	0
Liabilities, Transfers out of Level 3	$ 0

Leases (Additional Information) (Details)	Mar. 31, 2019
Lease Agreements [Member] \| Geographic Distribution, Domestic [Member]
Lessor, Lease, Description [Line Items]
Option to extend	The Company has the option to extend the lease agreement for a period of five years

Leases - Schedule of Components of lease cost (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Leases [Abstract]
Operating lease cost	$ 610
Short-term cost	43
Total lease cost	$ 653
Weighted-average remaining lease term	1 year 9 months 14 days
Weighted-average discount rate	6.00%

Leases - Schedule of maturities of operating leases (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Lessee, Operating Lease, Liability, to be Paid [Abstract]
2023	$ 850
2024	559
2025 and thereafter	0
Total lease payments	1,409
Less: Imputed interest	(204)
Present value of lease liabilities	1,205
Less: Current portion of lease liabilities	(661)	$ 0
Total lease liabilities, non-current	$ 544

- Definition

Amount, excluding unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

+ References + Details

Leases - Schedule of future minimum lease payments required under operating leases (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Leases [Abstract]
2022	$ 669
2023	652
2024	559
2025 and thereafter	0
Total	$ 1,880

Loans Payable - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended			12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	May 31, 2020	Dec. 31, 2022	Oct. 31, 2018	Apr. 30, 2017
Short Term Debt [Line Items]
Proceeds from issuance of debt			$ 15.0
Bridge Loan
Short Term Debt [Line Items]
Debt Instrument, fair value		$ 2.1
Proceeds from issuance of debt			$ 1.8
Debt instrument, interest rate			10.00%
Debt conversion, original debt, amount		1.8
Proceeds from debt payable in different currency, description				payable in renminbi (RMB) at an established USD/RMB exchange rate, based on an average of the previous five working days before May 8, 2020.
Debt conversion to stock, aggregate debt plus accrued interest		1.9
Debt conversion, accrued interest, amount		$ 0.1
Series C convertible preferred stock
Short Term Debt [Line Items]
Convertible preferred stock, shares issued		7,500,665
Series C convertible preferred stock \| Loans Payable
Short Term Debt [Line Items]
Proceeds from promissory note receivable	$ 1.9
Series C convertible preferred stock \| Bridge Loan
Short Term Debt [Line Items]
Debt conversion, converted instrument, shares		167,159
Series A convertible preferred stock
Short Term Debt [Line Items]
Convertible preferred stock, shares issued						2,089,285
Series A convertible preferred stock \| LAV Affiliate
Short Term Debt [Line Items]
Convertible preferred stock, shares issued		767,857
Series B convertible preferred stock
Short Term Debt [Line Items]
Convertible preferred stock, shares issued					2,384,195
Series B convertible preferred stock \| LAV Affiliate
Short Term Debt [Line Items]
Convertible preferred stock, shares issued		216,450
L A V Series A And Series B Promissory Note \| Loans Payable
Short Term Debt [Line Items]
Outstanding amount settlement from proceeds received from note receivable	$ 10.8
2020 Notes
Short Term Debt [Line Items]
Debt instrument, interest rate			10.00%
Debt conversion, original debt, amount			$ 15.9
Debt conversion to stock, aggregate debt plus accrued interest		$ 15.9
2020 Notes \| Series C convertible preferred stock
Short Term Debt [Line Items]
Debt conversion, converted instrument, shares		1,366,820

Convertible Preferred Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Dec. 31, 2020	Oct. 31, 2018	Apr. 30, 2017	Feb. 28, 2021
Bridge Loan
Convertible Preferred Stock [Line Items]
Debt conversion to stock, aggregate debt plus accrued interest	$ 1.9
2020 Notes
Convertible Preferred Stock [Line Items]
Debt conversion to stock, aggregate debt plus accrued interest	$ 15.9
Series A convertible preferred stock
Convertible Preferred Stock [Line Items]
Convertible preferred stock, shares issued			2,089,285
Convertible preferred stock, par value			$ 10.50
Aggregate purchase price			$ 21.9
Series A convertible preferred stock \| LAV Affiliate
Convertible Preferred Stock [Line Items]
Convertible preferred stock, shares issued	767,857
Series A convertible preferred stock \| Terns China
Convertible Preferred Stock [Line Items]
Proceeds from sale of convertible preferred stock			$ 8.0
Series B convertible preferred stock
Convertible Preferred Stock [Line Items]
Convertible preferred stock, shares issued		2,384,195
Convertible preferred stock, par value		$ 30.80
Aggregate purchase price		$ 73.4
Series B convertible preferred stock \| LAV Affiliate
Convertible Preferred Stock [Line Items]
Convertible preferred stock, shares issued	216,450
Series B convertible preferred stock \| Terns China
Convertible Preferred Stock [Line Items]
Proceeds from sale of convertible preferred stock		$ 6.7
Series C convertible preferred stock
Convertible Preferred Stock [Line Items]
Convertible preferred stock, shares issued	7,500,665
Convertible preferred stock, par value	$ 11.65
Gross proceeds from issuance and conversion of convertible preferred stock	$ 87.4
Series C convertible preferred stock \| Bridge Loan
Convertible Preferred Stock [Line Items]
Debt conversion, converted instrument, shares	167,159
Series C convertible preferred stock \| 2020 Notes
Convertible Preferred Stock [Line Items]
Debt conversion, converted instrument, shares	1,366,820
IPO
Convertible Preferred Stock [Line Items]
Convertible preferred stock, shares issued upon conversion				16,079,230

Convertible Preferred Stock - Schedule of Convertible Preferred Stock (Details) - shares	Dec. 31, 2020	Oct. 31, 2018	Apr. 30, 2017
Series A convertible preferred stock
Convertible Preferred Stock [Line Items]
Convertible preferred stock,authorized	40,000,000
Convertible preferred stock, shares issued			2,089,285
Convertible Preferred Stock Outstanding	2,857,142
Series B convertible preferred stock
Convertible Preferred Stock [Line Items]
Convertible preferred stock,authorized	36,409,088
Convertible preferred stock, shares issued		2,384,195
Convertible Preferred Stock Outstanding	2,600,645
Series C convertible preferred stock
Convertible Preferred Stock [Line Items]
Convertible preferred stock,authorized	111,619,996
Convertible preferred stock, shares issued	7,500,665
Convertible Preferred Stock Outstanding	7,500,665

Common Stock and Stock-Based Compensation - Schedule of Common Stock Shares Reserved for Issuance (Details) - shares	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares reserved	22,323,490	4,956,107
Options Outstanding Under Incentive Award Plans
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares reserved	4,823,928	3,577,485
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares reserved	128,280	0
Shares Available for Future Grant under Incentive Award Plans
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares reserved	1,107,362	1,138,622
Shares Available for Future Grant under Employee Stock Purchase Plans
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares reserved	323,920	240,000
Shares Available For Future Grant Under Employment Inducement Award Plans [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares reserved	1,310,000	0
Pre-Funded Warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares reserved	14,630,000	0

Common Stock and Stock-Based Compensation - Additional Information (Details)		1 Months Ended	12 Months Ended
	Jan. 01, 2023 shares	Feb. 28, 2021 shares	Dec. 31, 2022 USD ($) Plan Vote $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, voting rights			Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends
Number of voting rights per share \| Vote			1
Cash dividends declared or paid \| $			$ 0
Number of stock-based compensation plans \| Plan			3
Share-based compensation, vesting period			4 years
Share-based compensation, expiration period			10 years
Total shares initially reserved			22,323,490	4,956,107
Common stock, authorized		150,000,000	150,000,000	150,000,000	299,700,000
Common stock, par value \| $ / shares			$ 0.0001	$ 0.0001	$ 0.0001
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense related to unvested stock options \| $			$ 21,200,000	$ 28,600,000
Unrecognized stock-based compensation expense recognized period			2 years 2 months 8 days
Fair Value Of Options Vested \| $			$ 10,900,000	$ 7,800,000
Number of Shares, Granted			1,405,020	1,429,850
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense related to unvested stock options \| $			$ 400,000	$ 0
Unrecognized stock-based compensation expense recognized period			3 years 5 months 15 days
Fair Value Of Options Vested \| $			$ 0	$ 100,000
2021 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, number of shares authorized		2,400,007
Increase of number of authorized shares reserved for issuance under the 2021 Plan	2,686,158
Share-based payment award, shares available for future grants			1,107,362
Increase of authorized shares, percent of common stock outstanding		5.00%
2017 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase of number of authorized shares reserved for issuance under the 2021 Plan		0
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value of the shares on the offering date			85.00%
Percentage of fair market value of the shares on the purchase date			85.00%
Increase of number of authorized shares reserved for issuance under the 2021 Plan	537,231
Share-based payment award, shares available for future grants			323,920
Total shares initially reserved		240,000
Increase of authorized shares, percent of common stock outstanding		1.00%
Unrecognized stock-based compensation expense recognized period			1 year 6 months 10 days
Unrecognized stock-based compensation expense related to unvested employee stock purchases \| $			$ 200,000
Issuance of common stock under employee stock purchase plan			168,772
2021 Employee Stock Purchase Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation rate of payroll deduction			15.00%
2022 Inducement Plan Member
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, authorized			1,400,000
Number of Shares, Granted			1,310,000
Pre-Funded Warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Pre-funded warrants to purchase			14,630,000
Pre-funded warrant price \| $ / shares			$ 2.4199
Common stock, par value \| $ / shares			$ 0.0001

Common Stock and Stock-Based Compensation - Summary of Stock Option Activity (Details) - Stock Options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Number of Shares
Number of Shares, Outstanding beginning balance	3,577,485	2,466,670
Number of Shares, Granted	1,405,020	1,429,850
Number of Shares, Exercised	(10,000)	(156,104)
Number of Shares, Forfeited	(148,577)	(162,931)
Number of Shares, Outstanding ending balance	4,823,928	3,577,485	2,466,670
Number of Shares, Exercisable	2,537,942
Number of Shares, Vested and expected to vest	4,823,928
Weighted-Average Exercise Price
Weighted-Average Exercise Price, Outstanding beginning balance	$ 9.72	$ 8.03
Weighted-Average Exercise Price, Granted	4.44	11.83
Weighted-Average Exercise Price, Exercised	0.00	5.86
Weighted-Average Exercise Price, Forfeited	9.29	8.28
Weighted-Average Exercise Price, Outstanding ending balance	8.22	$ 9.72	$ 8.03
Weighted-Average Exercise Price, Exercisable	9.14
Weighted-Average Exercise Price, Vested and expected to vest	$ 8.22
Weighted-Average Remaining Contractual Term and Aggregate Intrinsic Value
Weighted-Average Remaining Contractual Term, Outstanding	8 years 5 months 15 days	9 years 1 month 2 days	9 years 7 months 9 days
Weighted-Average Remaining Contractual Term, Exercisable	7 years 11 months 19 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	8 years 5 months 15 days
Aggregate Intrinsic Value, Outstanding, beginning balance	$ 491	$ 21,678
Aggregate Intrinsic Value, Outstanding, Exercised	21	858
Aggregate Intrinsic Value, Outstanding, ending balance	11,721	$ 491	$ 21,678
Aggregate Intrinsic Value, Exercisable	3,664
Aggregate Intrinsic Value, Vested and expected to vest	$ 11,721

Common Stock and Stock-Based Compensation - Schedule of Stock Options Weighted Average Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Employee Stock Purchase Plans
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	10 months 20 days	9 months
Expected volatility	70.08%	60.82%
Risk-free interest rate	2.55%	0.17%
Fair value of underlying common stock	$ 2.95	$ 6.53
Weighted average grant-date fair value per share	$ 1.25	$ 2.33
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 11 months 26 days	6 years 10 days
Expected volatility	72.67%	76.60%
Risk-free interest rate	2.29%	1.12%
Fair value of underlying common stock	$ 4.44	$ 11.83
Fair value of option	$ 2.91	$ 7.82

Common Stock and Stock-Based Compensation - Summary of Restricted Stock Award Activity (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Number of Shares
Number of Shares, Unvested restricted common stock, beginning balance	0	83,334
Number of Shares, Vested		(71,429)
Number of Shares, Forfeited	(19,470)	(11,905)
Number of Shares, Granted	147,750
Number of Shares, Unvested restricted common stock, ending balance	128,280	0
Grant-Date Fair Value
Grant-Date Fair Value, Unvested restricted common stock, beginning balance	$ 0	$ 1.96
Grant-Date Fair Value, Vested		1.96
Grant-Date Fair Value, Forfeited	3.37	1.96
Grant-Date Fair Value, Granted	3.99
Grant-Date Fair Value, Unvested restricted common stock, ending balance	$ 4.09	$ 0

Common Stock and Stock-Based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 10,768	$ 8,146
Research and Development Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	3,025	2,055
General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 7,743	$ 6,091

Income Tax - Components of (Loss) Income Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
U.S.	$ (60,226)	$ (49,733)
Foreign	239	83
Loss before income taxes	$ (59,987)	$ (49,650)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Income Tax - Schedule of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Current
Federal	$ 0	$ 105
State	5	1
Foreign	299	313
Total current	304	419
Deferred
Foreign	54	89
Total deferred	54	89
Total income tax expense	$ 358	$ 508

- Definition

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

+ References + Details

Income Tax - Reconciliation between Effect of Applying Federal Statutory Rate and Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Tax benefit at U.S. statutory rate	21.00%	21.00%
State income taxes, net of Federal tax benefit	(0.01%)	0.00%
Foreign income taxed at non-U.S. rates	(0.02%)	(0.37%)
Domestication	0.00%	32.57%
Other permanent items	(0.11%)	(0.04%)
Stock-based compensation	(0.47%)	(0.52%)
Research and development credits	3.00%	2.14%
Unrecognized tax benefit	(0.57%)	(1.18%)
Global intangible low-taxed income	(1.09%)	(0.04%)
Increase in valuation allowance	(21.93%)	(54.53%)
Other	(0.40%)	(0.05%)
Effective tax rate	(0.60%)	(1.02%)

Income Tax - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Accruals and reserves	$ 820	$ 575
Intangibles	12,929	14,574
Stock-based compensation	3,549	1,582
Net operating loss	13,841	10,271
Research and development credits	3,650	1,930
Lease liability	241	0
Capitalized research and development	7,410	0
Other	61	87
Valuation allowance	(42,207)	(28,849)
Total deferred tax assets	294	170
Deferred tax liabilities:
Fixed assets	(50)	(78)
Operating lease assets	(207)	0
Total deferred tax liabilities	(257)	(78)
Net deferred tax assets	$ 37	$ 92

Income Tax - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Taxes [Line Items]
Net deferred tax assets	$ 37	$ 92
U.S. federal statutory tax rate	21.00%	21.00%
California R&E credit carryforward	$ 3,650	$ 1,930
Unrecognized tax benefits	6,316	5,849	$ 5,406
Total amount of gross interest and penalties accrued	300	100
Foreign Tax Positions
Income Taxes [Line Items]
Federal research and development credit carryforwards	4,100	1,900
California R&E credit carryforward	2,000	1,700
Unrecognized tax benefits	6,300	5,800
Unrecognized tax benefits, that would affect income tax expense	$ 4,200	4,500
Foreign Tax Positions \| Research and Experimentation (R&E)
Income Taxes [Line Items]
Operating loss carryforwards, expiration date	Dec. 31, 2039
Federal
Income Taxes [Line Items]
Operating loss carryforwards	$ 65,800	48,700
State
Income Taxes [Line Items]
Operating loss carryforwards	$ 700	$ 400
Operating loss carryforwards, expiration date	Dec. 31, 2041

Income Tax - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefit at beginning of year	$ 5,849	$ 5,406
Increases related to prior year tax positions	150	365
Increases related to current year tax position	706	451
Decreases related to prior year tax positions	(389)	(373)
Unrecognized tax benefit at end of year	$ 6,316	$ 5,849

Net Loss Per Share of Common Stock - Schedule of Computation of Basic and Diluted Net Loss per Common Share (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Numerator:
Net loss	$ (60,345)	$ (50,158)

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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+ Details

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Due Under Operating Leases (Details) $ in Thousands	Dec. 31, 2022 USD ($)
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Total lease payments	$ 1,409

Assignment, License and Collaboration Agreements - Additional Information (Details)	1 Months Ended						12 Months Ended
	Jul. 31, 2022 USD ($)	Nov. 30, 2021 USD ($)	Jul. 31, 2020 USD ($)	Jun. 30, 2019 CNY (¥)	Mar. 31, 2018 USD ($)	Feb. 28, 2018 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
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