Nature of the Business, Basis of Presentation and Summary of Significant Accounting Policies | 1. Nature of the Business, Basis of Presentation and Summary of Significant Accounting Policies Nature of the Business Terns Pharmaceuticals, Inc. (Terns or the Company) is a clinical-stage biopharmaceutical company developing a portfolio of small-molecule product candidates to address serious diseases including oncology 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, 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 condensed 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, for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The Company’s unaudited condensed consolidated financial statements have been prepared in conformity with U.S. GAAP. All intercompany balances and transactions have been eliminated in consolidation. The condensed consolidated balance sheet as of December 31, 2023 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements. Operating results for the three and nine months ended September 30, 2024 are not necessarily indicative of the results that may be expected for the year ending December 31, 2024 or for any other future periods. Unaudited Interim Financial Information These unaudited condensed consolidated financial statements include all adjustments necessary, consisting of only normal recurring adjustments, to fairly state the financial position and the results of the Company’s operations and cash flows for interim periods in accordance with U.S. GAAP. Interim period results are not necessarily indicative of results of operations or cash flows for a full year or any subsequent interim periods. The accompanying unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto in the Company’s Annual Report on Form 10-K (the Annual Report) for the fiscal year ended December 31, 2023, as filed with the SEC on March 14, 2024. There have been no significant changes to the Company's significant accounting policies described in Note 1, Nature of the Business, Basis of Presentation and Summary of Significant Accounting Policies, in Notes to Consolidated Financial Statements in Item 8 of Part II of the Form 10-K for the fiscal year ended December 31, 2023. Any reference to these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (ASC) and Accounting Standards Updates (ASUs) of the Financial Accounting Standards Board (FASB). 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 (SEC), which became effective in March 2022. As of September 30, 2024, there were 9,781,673 shares of our common stock sold for aggregate net proceeds of $ 66.6 million after deducting commissions and offering expenses pursuant to this agreement. There were no sales of the Company's common stock pursuant to this agreement during the nine months ended September 30, 2024. In May 2023, the Company entered into a Sales Agreement with 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 $ 150.0 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 SEC, which became effective in February 2023. There were no sales of the Company's common stock pursuant to this agreement through September 30, 2024 . September 2024 Financing In September 2024, the Company issued 14,064,048 shares of its common stock at a public offering price of $ 10.50 per share and, to certain investors in lieu of common stock, pre-funded warrants to purchase 2,380,952 shares of common stock at a public offering price of $ 10.4999 per pre-funded warrant in an underwritten public offering. The purchase price per share of each pre-funded warrant represents the per share public offering price for the common stock, minus the $ 0.0001 per share exercise price of each such pre-funded warrant. Aggregate net proceeds were $ 161.9 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 $ 23.4 million was allocated to the pre-funded warrants and recorded as a component of additional paid-in capital. No pre-funded warrants have been exercised as of September 30, 2024 . Summary of Significant Accounting Policies Use of Estimates The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires the 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 condensed 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 may 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 the condensed consolidated statements of operations and comprehensive loss and 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. Gains and losses on securities sold are recorded based on the specific identification method and are included in Interest income, net in the condensed consolidated statements of operations and comprehensive loss. The Company has not incurred any material realized gains or losses from sales of securities to date. The Company assesses its available-for-sale debt securities for impairment as of each reporting date in order to determine if a portion of any decline in fair value below carrying value is the result of a credit loss. The Company records credit losses in the condensed consolidated statements of operations and comprehensive loss as credit loss expense within other expense, net, which is limited to the difference between the fair value and the amortized cost of the security. To date, the Company has not recorded any credit losses on its available-for-sale debt securities. Interest receivable related to the Company's available-for-sale debt securities is presented as marketable securities on the Company's condensed consolidated balance sheets. The Company writes off interest receivable once it has determined that the asset is not realizable. To date, the Company has not written off any interest receivables associated with its marketable securities. 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 ROU 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. 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 (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. 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: (in thousands) September 30, 2024 December 31, 2023 Research and development costs $ 2,342 $ 2,010 Compensation and benefit costs 4,280 5,683 Accrued professional fees 2,254 855 Other 477 278 Total accrued expenses and other current liabilities $ 9,353 $ 8,826 Executive Leadership Transition In August 2023, Bryan Yoon, former chief operating officer and general counsel, and Mark Vignola, Ph.D., chief financial officer, received retention awards payable in cash in the aggregate amount of $ 0.5 million for Mr. Yoon and $ 0.7 million for Dr. Vignola. Each retention award was payable in two installments of 33% of the award on February 1, 2024 and 67% of the award on August 1, 2024, subject to the applicable officer’s continued employment with the Company through such date. Expense was recognized on a straight-line basis over the requisite service period. During the nine months ended September 30, 2024, the Company recognized an expense of $ 0.7 million related to the retention awards. The retention awards were fully paid as of September 30, 2024. The expenses were recognized as operating expenses within the Condensed Consolidated Statements of Operations and Comprehensive Loss under General and administrative. In July 2024, Mr. Yoon entered into a separation agreement with the Company. The separation agreement provided for Mr. Yoon’s continued service as chief operating officer and special counsel for a transition period until September 3, 2024. Pursuant to the separation agreement, Mr. Yoon is entitled to receive severance in the amount of $ 0.5 million , equivalent to 12 months of his annual base salary, the remaining unpaid portion of his retention award of $ 0.3 million and a pro rata portion of his target annual bonus for 2024 of $ 0.1 million . During the three months ended September 30, 2024, the Company recorded an accrued liability and recognized expense of $ 0.6 million related to the departure of the former chief operating officer. As of September 30, 2024, the ending accrued liability was $ 0.7 million and is presented within the Condensed Consolidated Balance Sheets under Accrued expenses and other current liabilities. Additionally, the separation agreement provided that the time for Mr. Yoon to exercise any outstanding equity award that is vested as of the separation date shall continue to April 30, 2025. As a result of the change in terms for these option grants to Mr. Yoon, the Company recognized an additional $ 0.6 million in stock-based compensation expense during the three months ended September 30, 2024. The expenses were recognized as operating expenses within the Condensed Consolidated Statements of Operations and Comprehensive Loss under General and administrative. In July 2024, Dr. Vignola entered into a transition agreement with the Company. The transition agreement provides for Dr. Vignola’s continued service as chief financial officer for a transition period until the date of his separation from employment, anticipated to be February 1, 2025. Pursuant to the transition agreement, Dr. Vignola is entitled to receive severance in the amount of $ 0.5 million , equivalent to 12 month s of his annual base salary, the remaining unpaid portion of his retention award of $ 0.5 million , his target annual bonus for 2024 of $ 0.2 million and, as applicable based on the separation date, a pro rata portion of his target annual bonus for 2025. In addition, the Company has agreed to pay Dr. Vignola an additional retention bonus in the amount of $ 0.5 million , provided Dr. Vignola remains employed until February 1, 2025, with such additional retention bonus being payable in a pro rata amount under certain conditions per the transition agreement. During the three months ended September 30, 2024, the Company recorded an accrued liability and recognized expense of $ 0.8 million related to the planned transition of the chief financial officer. As of September 30, 2024, the ending accrued liability was $ 0.9 million and is presented within the Condensed Consolidated Balance Sheets under Accrued expenses and other current liabilities. Additionally, the transition agreement provided that the time for Dr. Vignola to exercise any outstanding equity award that is vested as of the separation date shall continue to the end of the 12th month following the separation date. As a result of the change in terms for these option grants to Dr. Vignola, the Company recognized an additional $ 0.4 million in stock-based compensation expense during the three months ended September 30, 2024. The expenses were recognized as operating expenses within the Condensed Consolidated Statements of Operations and Comprehensive Loss under General and administrative. In November 2023, Erin Quirk, M.D., former president and head of research & development, received a retention award payable in cash in the aggregate amount of $ 0.6 million and a recognition bonus in the aggregate amount of $ 0.1 million. The retention award was payable in two installments of 33% of the award on February 1, 2024, and 67% of the award on August 1, 2024, and the recognition bonus was payable on January 1, 2024, subject to Dr. Quirk's continued employment with the Company through such date. Expense was recognized on a straight-line basis over the requisite service period. On May 7, 2024, Dr. Quirk entered into a separation agreement with the Company. Pursuant to the separation agreement, Dr. Quirk was entitled to receive severance in the amount of $ 0.2 million and the remaining unpaid portion of her recognition bonus of $ 0.4 million . As of June 30, 2024, there was no ending accrued liability as all balances have been paid. As of June 30, 2024, the vesting of each equity award held by Dr. Quirk was accelerated with respect to the number of shares of common stock that would have become vested had Dr. Quirk remained employed at the Company through August 31, 2024, and the time for Dr. Quirk to exercise any vested stock options shall continue up to November 30, 2024. As a result of the change in terms for these option grants to Dr. Quirk, in May 2024, the Company recognized $ 0.4 million in stock-based compensation expense during the nine months ended September 30, 2024. The expenses were recognized as operating expenses within the Condensed Consolidated Statements of Operations and Comprehensive Loss under Research and development. In August 2023, the Company and Senthil Sundaram, former chief executive officer, entered into a separation agreement. Pursuant to the separation agreement, Mr. Sundaram was entitled to receive severance in the amount of $ 0.6 million and 100 % of his annual target discretionary bonus for 2023 in the amount of $ 0.3 million. During the year ended December 31, 2023, the Company recorded an accrued liability and recognized expense of $ 0.9 million related to the departure of the former chief executive officer. As of September 30, 2024, the ending accrued liability was $ 0.1 million and is presented within the Condensed Consolidated Balance Sheets under Accrued expenses and other current liabilities. The vesting of each equity award held by Mr. Sundaram was fully accelerated as of December 31, 2023. As a result of the change in service period for all outstanding unvested option grants to the Company’s former chief executive officer in August 2023, the Company recognized $ 10.5 million in stock-based compensation expense during the three and nine months ended September 30, 2023. The expense was recognized as operating expenses within the Condensed Consolidated Statements of Operations and Comprehensive Loss under General and administrative. 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. The Company accrues interest and related penalties, if applicable, on all tax exposures for which reserves have been established consistent with jurisdictional tax laws. The Company includes interest and penalties related to unrecognized tax benefits within the provision for income taxes. The Company recorded income tax expense for the three months ended September 30, 2024 and 2023 of $ 0.1 million. The Company recorded income tax expense for the nine months ended September 30, 2024 and 2023 of $ 0.2 million. The expenses are primarily related to foreign income tax expenses from China. 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 relates to stock options, restricted stock units (RSUs) with service conditions, and RSUs with market conditions issued under the Company’s equity incentive plan and rights to acquire stock granted under the Company’s employee stock purchase plan (ESPP). Grants are 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. Forfeitures are recognized as they occur. The Black-Scholes option pricing model estimates the fair value of stock options with time-based vesting and rights to acquire stock under the ESPP. 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 is calculated based upon the Company’s common stock valuation on the date of the grant. The fair value of RSUs with service conditions is based upon the Company’s common stock valuation on the date of the grant. The Monte Carlo simulation model estimates the fair value of the RSUs with market conditions, using inputs for the common stock valuation on the date of the grant, volatility, the risk-free interest rate, and the dividend yield. Compensation expense is recognized on a straight-line basis over the derived service period commencing on the grant date. The derived service period is the median duration of the successful stock price paths to meet the price goal for each tranche as simulated in the Monte Carlo valuation model. If the related market condition is achieved earlier than its estimated derived service period, the stock-based compensation expense is accelerated, and a cumulative catch-up expense is recorded during the period in which the market condition is met. Pre-funded Warrants Pre-funded warrants are classified as a component of permanent stockholders’ equity within additional paid-in capital and are 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 value of the pre-funded warrants is known at issuance, as their sales price approximates their fair value, and net proceeds from the sale are recorded as a component of additional paid-in capital. Net Loss Per Share of Common Stock 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 September 30, 2024 included pre-funded warrants, as the warrants were issued for minimal consideration and were immediately exercisable. 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 potentially dilutive shares. The Company reported a net loss for the three and nine months ended September 30, 2024 and 2023. 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: September 30, 2024 2023 Options to purchase common stock 10,964,022 8,295,869 Unvested restricted stock units with service conditions 580,104 364,594 Unvested restricted stock units with market conditions 150,000 — Shares issuable under employee stock purchase plan 50,646 54,900 Total 11,744,772 8,715,363 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. 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. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies. The Company is an emerging growth company as defined in the Jumpstart Our Business Startups Act of 2012, as amended (JOBS Act). Under the JOBS Act, emerging growth companies have extended transition periods available for complying with new or revised accounting standards. The Company has elected to use this exemption to delay adopting new or revised accounting standards until such time as those standards apply to private companies. Where allowable, the Company has early adopted certain standards as described below. Recently Issued Accounting Pronouncements Not Yet Adopted In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (ASU 2023-09), which requires additional income tax disclosures in the annual consolidated financial statements. The amendments in ASU 2023-09 are intended to enhance the transparency and decision usefulness of income tax discl |