Summary of Significant Accounting Policies | 2. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements for the years ended December 31, 2022 and 2021 , have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”) and Generally Accepted Accounting Principles in the United States (“U.S. GAAP”) for financial information, which prescribes elimination of all significant intercompany accounts and transactions in the accounts of the Company and its wholly owned subsidiary, Cue Biopharma Securities Corp., which was incorporated in the Commonwealth of Massachusetts in December 2018. In the opinion of management, these financial statements reflect all adjustments which are necessary for a fair statement of the Company’s financial position and results of its operations, as of and for the periods presented. Public Offerings In June 2020, the Company entered into an at-the-market ("ATM") equity offering sales agreement (the “June 2020 ATM Agreement”) with Stifel Nicolaus & Company, Inc. ("Stifel") to sell shares of the Company’s common stock for aggregate gross proceeds of up to $ 40 million, from time to time, through an ATM equity offering program under which Stifel would act as sales agent. As of December 31, 2022, the Company sold an aggregate 2,099,700 shares of common stock under the June 2020 ATM Agreement for proceeds of approximately $ 32.7 million , net of commissions paid, but excluding transaction expense. The June 2020 ATM Agreement terminated in October 2021 prior to entering into the October 2021 ATM Agreement (as defined below). In October 2021, the Company entered into an open market sale agreement (the “October 2021 ATM Agreement”) with Jefferies LLC ("Jefferies"), as agent, to sell shares of the Company’s common stock for aggregate gross proceeds of up to $ 80 million, from time to time, through an ATM equity offering program. The October 2021 ATM Agreement will terminate upon the earliest of (a) the sale of $ 80 million of shares of the Company’s common stock pursuant to the October 2021 ATM Agreement or (b) the termination of the October 2021 ATM Agreement by the Company or Jefferies. During the year ended December 31, 2022, the Company sold 3,117,220 shares of common stock under the October 2021 ATM Agreement for proceeds of approximately $ 16.6 million, net of commissions paid, but excluding transaction expense. As of December 31, 2022, the Company sold an aggregate 3,593,407 shares of common stock under the October 2021 ATM Agreement for proceeds of approximately $ 23.6 million, net of commissions paid, but excluding transaction expenses, since its inception. Issuance of Securities through a Private Placement On November 14, 2022, the Company entered into securities purchase agreements with accredited investors pursuant to which, on November 16, 2022, the Company issued and sold to such investors in a private placement an aggregate of 7,656,966 shares of common stock and, in lieu of shares of common stock to certain investors, pre-funded warrants (or "Pre-Funded Warrants") to purchase an aggregate of 1,531,440 shares of common stock, and, in each case, accompanying warrants, or Warrants, to purchase an aggregate of up to 9,188,406 additional shares of common stock (or Pre-Funded Warrants in lieu thereof) at a price of $ 3.265 per share and accompanying Warrant (or $ 3.2649 per Pre-Funded Warrant and accompanying Warrant), (such financing, the "PIPE Financing"). The exercise price of the Warrants is $ 3.93 per share, or if exercised for a Pre-Funded Warrant in lieu thereof, $ 3.9299 per Pre-Funded Warrant. The Warrants are exercisable at any time after they are issued and ending on the fifth anniversary of the closing. The Pre-Funded Warrants are exercisable at any time after they are issued and will not expire. The Company received aggregate gross proceeds from the PIPE Financing of approximately $ 30 million, before deducting placement agent fees and offering expenses of approximately $ 2.6 million. Piper Sandler & Co. acted as lead placement agent and Public Ventures LLC acted as co-placement agent for the PIPE Financing. The Warrants are classified as a component of permanent equity because they are freestanding financial instruments that are legally detachable and separately exercisable from the shares of common stock with which they were issued, are immediately exercisable, do not embody an obligation for the Company to repurchase its shares, and permit the holders to receive a fixed number of shares of common stock upon exercise. In addition, the Warrants do not provide any guarantee of value or return at December 31, 2022, the weighted average exercise price is $ 3.93 and the weighted average contractual life is five years. The Pre-Funded Warrants do not have an expiration date. The Pre-Funded Warrants met the permanent equity criteria classification. The Pre-Funded Warrants are classified as a component of permanent equity because they are freestanding financial instruments that are legally detachable and separately exercisable from the shares of common stock with which they were issued, are immediately exercisable, do not embody an obligation for the Company to repurchase its shares, and permit the holders to receive a fixed number of shares of common stock upon exercise. In addition, the Pre-Funded Warrants do not provide any guarantee of value or return. Consolidation The accompanying consolidated financial statements include the Company and its wholly owned subsidiary, Cue Biopharma Securities Corp. The Company has eliminated all intercompany transactions. 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 the reported amounts of expenses during the reporting period. Significant estimates include estimates related to collaboration revenue, the accounting for potential liabilities and accrued expenses, the assumptions utilized in valuing stock-based compensation issued for services, the realization of deferred tax assets, and the useful life with respect to long-lived assets and intangibles. Actual results could differ from those estimates. COVID-19 Pandemic The extent to which the COVID-19 pandemic may continue to impact the Company’s business and financial results will depend on numerous evolving factors including, but not limited to: the extent of its impact on worldwide macroeconomic conditions, the speed of the anticipated recovery, access to capital markets, and governmental and business policies regarding the pandemic. The Company assessed certain accounting matters that generally require consideration of forecasted financial information in context with the information reasonably available to the Company and the unknown future impacts of the COVID-19 pandemic as of December 31, 2022 and through the date of the filing of this Annual Report on Form 10-K. The accounting matters assessed included, but were not limited to, estimates related to collaboration revenue, the accounting for potential liabilities and accrued expenses, the assumptions utilized in valuing stock-based compensation issued for services, the realization of deferred tax assets, and assessments of impairment related to long-lived assets and intangibles. The Company’s future assessment of the potential effects of the COVID-19 pandemic, as well as other factors, could result in material impacts to the Company’s consolidated financial statements in future reporting periods. Despite the Company’s efforts, the impact of the COVID-19 pandemic on its business depends on factors beyond the Company’s knowledge or control, including the supply-chain disruptions, as well as third-party actions taken to contain its spread and mitigate its public health effects. As a result, the Company is unable to estimate the extent to which the COVID-19 pandemic may negatively impact its financial results or liquidity in the future. Cash Concentrations The Company maintains its cash balances with a financial institution in federally insured accounts and may periodically have cash balances in excess of insurance limits. The Company maintains its accounts with a financial institution with a high credit rating. The Company has not experienced any losses to date and believes that it is not exposed to any significant credit risk on cash. On March 10, 2023, one of the financial institutions the Company has accounts with, Silicon Valley Bank ("SVB"), was closed and the FDIC was appointed receiver for the bank. The FDIC created a successor bridge bank, Silicon Valley Bridge Bank, N.A. (“SVBB”), and all deposits of SVB were transferred to SVBB under a systemic risk exception approved by the United States Department of the Treasury, the Federal Reserve and the FDIC. See further discussion in Note 18. Cash and Cash Equivalents The Company considers all highly liquid investments with a maturity of three months or less at the date of purchase to be cash equivalents. The Company currently invests available cash in money market funds. Marketable Securities Marketable securities consist of investments with original maturities greater than ninety days and less than one year from the balance sheet date. The Company classifies all of its investments as available-for-sale securities. Accordingly, these investments are recorded at fair value, which is based on quoted market prices. Unrealized gains and losses are recognized and determined on a specific identification basis and are included in other comprehensive loss. Realized gains and losses are determined on a specific identification basis and are included in other income on the consolidated statement of operations and comprehensive loss. Amortization and accretion of discounts and premiums is recorded in interest income. The Company has invested available cash in U.S. Treasury obligations. Restricted Cash The Company had $ 150,000 in restricted cash deposited with a commercial bank to collateralize a credit card as of December 31, 2022 and 2021. Property and Equipment Property and equipment is recorded at cost. Major improvements are capitalized, while maintenance and repairs are charged to expense as incurred. Gains and losses from dispositions of property and equipment are included in income and expense when realized. Amortization of leasehold improvements is provided using the straight-line method over the shorter of the lease term or the useful life of the underlying assets. Depreciation of property and equipment is provided using the straight-line method over the following estimated useful lives: Laboratory equipment 5 years Computer equipment 3 years Furniture and fixtures 3 - 8 years The Company recognizes depreciation and amortization expense in general and administrative expenses and in research and development expenses in the Company’s consolidated statements of operations and comprehensive loss, depending on how each category of property and equipment is utilized in the Company’s business activities. Trademark Trademark consists of the Company’s right, title and interest to the CUE BIOLOGICS Mark, and any derivative mark incorporating CUE, throughout the world, together with all associated goodwill and common law rights appurtenant thereto, including, but not limited to, any right, title and interest in any corporate name, company name, business name, trade name, dba, domain name, or other source identifier incorporating CUE. The Company has classified the trademark as a component of other long-term assets, having a useful life of 15 years. The Company evaluates the status of this intangible asset for amortization and impairment at each year end reporting date. The Company recorded $ 11,666 in amortization related to the trademark at December 31, 2022 and 2021. Debt Issuance Costs Debt issuance costs are deferred and presented as a reduction to long-term debt. Debt issuance costs are amortized using the effective interest rate method over the term of the loan. Amortization of deferred debt issuance costs are included in interest expense in the consolidated statements of operations and other comprehensive loss. Revenue Recognition The Company recognizes collaboration revenue under certain of the Company’s license and collaboration agreements that are within the scope of Accounting Standards Codification (“ASC”), Topic 606, Revenue from Contracts with Customers (“ASC 606”). The Company’s contracts with customers typically include promises related to licenses to intellectual property and research and development services. 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 non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment 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 progress for purposes of recognizing revenue from non-refundable, up-front fees. Accordingly, the transaction price is generally comprised of a fixed fee due at contract inception and variable consideration in the form of milestone payments due upon the achievement of specified events and tiered royalties earned when customers recognize net sales of licensed products. The Company measures the transaction price based on the amount of consideration to which it expects to be entitled in exchange for transferring the promised goods and/or services to the customer. The Company utilizes the “most likely amount” method to estimate the amount of variable consideration, to predict the amount of consideration to which it will be entitled for its one open contract. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. At the inception of each arrangement that includes development and regulatory milestone payments, the Company evaluates whether the associated event is considered probable of achievement and estimates the amount to be included in the transaction price using the most likely amount method. Research and Development Expenses Research and development expenses consist primarily of compensation costs, fees paid to consultants, outside service providers and organizations (including research institutes at universities), facility costs, and development and clinical trial costs with respect to the Company’s drug product candidates. Research and development expenses incurred under contracts are expensed ratably over the life of the underlying contracts, unless the achievement of milestones, the completion of contracted work, or other information indicates that a different pattern of performance is more appropriate. Other research and development expenses are charged to operations as incurred. Nonrefundable advance payments are recognized as an expense as the related services are performed. The Company evaluates whether it expects the services to be rendered at each quarter end and year end reporting date. If the Company does not expect the services to be rendered, the advance payment is charged to expense. Nonrefundable advance payments for research and development services are included in prepaid and other current assets on the balance sheet. To the extent that a nonrefundable advance payment is for contracted services to be performed within 12 months from the reporting date, such advance is included in current assets; otherwise, such advance is included in non-current assets. The Company evaluates the status of its research and development agreements and contracts, and the carrying amount of the related assets and liabilities, at each quarter end and year end reporting date, and adjusts the carrying amounts and their classification on the balance sheet as appropriate. Patent Expenses The Company is the exclusive worldwide licensee of, and has patent applications pending for, numerous domestic and foreign patents. Due to the significant uncertainty associated with the successful development of one or more commercially viable drug product candidates based on the Company’s research efforts and any related patent applications, all patent costs, including patent-related legal fees, filing fees and other costs are charged to general and administrative expense as incurred. For the years ended December 31, 2022 and 2021, patent expenses were approximately $ 2,142,000 and $ 2,259,000 , respectively. Licensing Fees and Costs Licensing fees and costs consist primarily of costs relating to the acquisition of the Company’s license agreement (the "Einstein License Agreement") with the Albert Einstein College of Medicine ("Einstein"), including related royalties, maintenance fees, milestone payments and product development costs. Licensing fees and costs are charged to research and development expense as incurred. Long-Lived Assets The Company reviews long-lived assets, consisting of property and equipment, for impairment at each fiscal year end or when events or changes in circumstances indicate the carrying value of these assets may exceed their current fair values. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized for the amount by which the carrying amount of the asset exceeds the fair value of the assets. Assets to be disposed of are separately presented in the balance sheet and reported at the lower of the carrying amount or fair value less costs to sell and are no longer depreciated. The Company has not historically recorded any impairment to its long-lived assets. In the future, if events or market conditions affect the estimated fair value to the extent that a long-lived asset is impaired, the Company will adjust the carrying value of these long-lived assets in the period in which the impairment occurs. During the year ended December 31, 2022, the Company sold furniture and fixtures and lab equipment with an acquisition cost of $ 43,000 and collected cash of $ 6,200 . The Company recorded a loss on the sale of fixed assets of $ 4,000 , which is presented in other income on the consolidated statement of operations and other comprehensive loss. During the year ended December 31, 2021, the Company sold fully depreciated lab equipment with an acquisition cost of $ 271,820 , and the Company recorded a gain on the sale of fixed assets of $ 21,550 , which is presented in other income on the consolidated statements of operations and other comprehensive loss. Leases The Company accounts for leases under ASC 842 Leases, which requires a lessee to record a right-of-use asset and a corresponding lease liability for most lease arrangements on the balance sheet. Under the standard, disclosure of key information about leasing arrangements to assist users of the financial statements with assessing the amount, timing and uncertainty of cash flows arising from leases are required. Stock-Based Compensation The Company periodically issues stock-based awards to officers, directors, employees, Scientific and Clinical Advisory Board members and consultants for services rendered. Such issuances vest and expire according to terms established at the issuance date. Stock-based payments to officers, directors, employees, Scientific and Clinical Advisory Board members and consultants, including grants of employee stock options, are recognized in the financial statements based on their grant date fair values. Stock option grants, which are generally time-vested, are measured at the grant date fair value and charged to operations on a straight-line basis over the service period, which generally approximates the vesting term. The Company also grants performance-based awards periodically to officers of the Company. The Company recognizes compensation costs related to performance awards over the requisite service period if and when the Company concludes that it is probable that the performance condition will be achieved. The fair value of stock options and restricted stock units is determined utilizing the Black-Scholes option-pricing model, which is affected by several variables, including the risk-free interest rate, the expected dividend yield, the life of the equity award, the exercise price of the stock option as compared to the fair value of the common stock on the grant date, and the estimated volatility of the common stock over the term of the equity award. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant. Until the Company has established a trading history for its common stock that approximates the expected term of the options, estimated volatility is based on the average historical volatilities of comparable public companies in a similar industry. The expected dividend yield is based on the current yield at the grant date; the Company has never declared or paid dividends and has no plans to do so for the foreseeable future. As permitted by Staff Accounting Bulletin No. 107, due to the Company’s limited trading history and option activity, management utilizes the simplified method to estimate the expected term of options at the date of grant. The Company recognizes the fair value of stock-based compensation in general and administrative expenses and in research and development expenses in the Company’s consolidated statements of operations and comprehensive loss, depending on the type of services provided by the recipient of the equity award. Income Taxes The Company accounts for income taxes under an asset and liability approach for financial accounting and reporting for income taxes. Accordingly, the Company recognizes deferred tax assets and liabilities for the expected impact of differences between the financial statements and the tax basis of assets and liabilities. The Company accounts for uncertainties in income tax law under a comprehensive model for the financial statement recognition, measurement, presentation and disclosure of uncertain tax positions taken or expected to be taken in income tax returns as prescribed by U.S. GAAP. The tax effects of a position are recognized only if it is “more-likely-than-not” to be sustained by the taxing authority as of the reporting date. If the tax position is not considered “more-likely-than-not” to be sustained, then no benefits of the position are recognized. The Company records a valuation allowance to reduce its deferred tax assets to the amount that is more likely than not to be realized. In the event the Company was to determine that it would be able to realize its deferred tax assets in the future in excess of its recorded amount, an adjustment to the deferred tax assets would be credited to operations in the period such determination was made. Likewise, should the Company determine that it would not be able to realize all or part of its deferred tax assets in the future, an adjustment to the deferred tax assets would be charged to operations in the period such determination was made. The Company is subject to U.S. federal and Massachusetts state income taxes. As the Company’s net operating losses have yet to be utilized, all previous tax years remain open to examination by federal and state taxing authorities in which the Company currently operates. For the year ended December 31, 2022, there is no provision for income taxes in the U.S. because the Company has historically incurred net operating losses and maintains a full valuation allowance against its net deferred assets. The reported amount of income tax expense for the years differs from the amount that would result from applying domestic federal statutory tax rates to pretax losses primarily because of changes in valuation allowance. The Company recognized approximately $ 495,000 of income tax expense related to the foreign taxes withheld from an upfront payment received from LG Chem, Ltd. (“LG Chem”) pursuant to a collaboration agreement with LG Chem (the “LG Chem Collaboration Agreement”) during the year ended December 31, 2021. The Company recognizes interest accrued relative to unrecognized tax benefits in interest expense and penalties in operating expense. During the years ended December 31, 2022 and 2021, the Company did not recognize any income tax related interest and penalties. The Company did not have any accruals for income tax related interest and penalties at December 31, 2022 and 2021. Comprehensive Income (Loss) Components of comprehensive income or loss, including net income or loss, are reported in the financial statements in the period in which they are recognized. Other comprehensive income or loss is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources. Net income (loss) and other comprehensive income (loss) are reported net of any related tax effect to arrive at comprehensive income (loss). Comprehensive income (loss) includes net income (loss) as well as changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. The Company’s only element of other comprehensive income (loss) in periods presented was unrealized gain or loss on available-for-sale securities. Earnings (Loss) Per Share The Company’s computation of earnings (loss) per share (“EPS”) for the respective periods includes basic and diluted EPS. Basic EPS is measured as the income (loss) attributable to common stockholders divided by the weighted average number of common shares outstanding for the period. Diluted EPS is similar to basic EPS but presents the dilutive effect on a per share basis of potential common shares that would result from the exercise of outstanding stock options and warrants as if they had been exercised at the beginning of the periods presented, or issuance date, if later. Potential common shares that have an anti-dilutive effect (i.e., those that increase income per share or decrease loss per share) are excluded from the calculation of diluted EPS. Basic and diluted loss per common share is the same for all periods presented because all outstanding stock options and warrants are anti-dilutive. At December 31, 2022 and 2021, the Company excluded the outstanding securities summarized below, which entitled the holders thereof to acquire shares of common stock, from its calculation of earnings per share, as their effect would have been anti-dilutive. December 31, 2022 2021 Common stock warrants 10,719,846 851,969 Common stock options 6,740,122 5,654,168 Nonvested restricted stock units — 98,335 Total 17,459,968 6,604,472 Fair Value of Financial Instruments The authoritative guidance with respect to fair value established a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three levels and requires that assets and liabilities carried at fair value be classified and disclosed in one of three categories, as presented below. Level 1. Observable inputs such as quoted prices in active markets for an identical asset or liability that the Company has the ability to access as of the measurement date. Financial assets and liabilities utilizing Level 1 inputs include active-exchange traded securities and exchange-based derivatives. Level 2. Inputs, other than quoted prices included within Level 1, which are directly observable for the asset or liability or indirectly observable through corroboration with observable market data. Financial assets and liabilities utilizing Level 2 inputs include fixed income securities, non-exchange based derivatives, mutual funds, and fair-value hedges. Level 3. Unobservable inputs in which there is little or no market data for the asset or liability which requires the reporting entity to develop its own assumptions. Financial assets and liabilities utilizing Level 3 inputs include infrequently-traded non-exchange-based derivatives and commingled investment funds and are measured using present value pricing models. The Company determines the level in the fair value hierarchy within which each fair value measurement falls in its entirety, based on the lowest level input that is significant to the fair value measurement in its entirety. In determining the appropriate levels, the Company performs an analysis of the assets and liabilities at each reporting period end. The Company had approximately $ 45,423,000 in cash equivalents and approximately $ 24,675,000 in short-term marketable securities that were measured and recorded at fair value on the Company’s balance sheet at December 31, 2022 . The Company had approximately $ 52,509,000 in cash equivalents and $ 0 in short-term marketable securities that were measured and recorded at fair value on the Company’s balance sheet at December 31, 2021. The carrying value of financial instruments (consisting of cash, a certificate of deposit, debt, accounts payable, accrued compensation and accrued expenses) is considered to be representative of their respective fair values due to the short-term nature of those instruments. Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (the "FASB") issued Accounting Standards Update ("ASU") No. 2016-13, Financial Instruments- Credit Losses: Measurement of Credit Losses on Financial Instruments (Topic 326) (CECL). The new standard requires entities to measure all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions and reasonable and supportable forecasts. The new standard is effective for annual reporting periods beginning after December 15, 2022, including interim reporting periods within each annual reporting period for smaller reporting companies. T he Company adopted ASU 2016-13 but there was no financial impact to the Company's consolidated financial statements for the year ended December 31, 2022. Management does not believe that any other recently issued, but not yet effective, authoritative guidance, if currently adopted, would have a material impact on the Company’s financial statement presentation or disclosures. |