Cullinan Therapeutics, Inc.

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Nature of Business and Basis of Presentation

Organization

Cullinan Therapeutics, Inc., together with its consolidated subsidiaries ("Cullinan" or "the Company"), is a clinical-stage biopharmaceutical company developing therapies for autoimmune diseases and cancer that was incorporated in September 2016 and has a principal place of business in Cambridge, Massachusetts. In April 2024, the Company changed its name from Cullinan Oncology, Inc. to Cullinan Therapeutics, Inc.

Liquidity

The Company has a history of significant operating losses and has had negative cash flows from operations since its inception and expects to continue to generate operating losses for the foreseeable future. Cullinan’s ultimate success depends on the outcome of its research and development activities as well as its ability to commercialize the Company’s product candidates. Cullinan is subject to a number of risks including, but not limited to, the need to obtain adequate additional funding for the ongoing and planned clinical development of its product candidates. Due to the numerous risks and uncertainties associated with pharmaceutical development, government regulation, potential commercialization, intellectual property, and our reliance on third parties the Company is unable to accurately predict the timing or amount of funds required to complete development of its product candidates, and costs could exceed Cullinan’s expectations for a number of reasons, including reasons beyond the Company’s control.

Since inception, Cullinan has funded its operations primarily through the sale of equity securities and from licensing or selling the rights to its product candidates. The Company expects that its cash, cash equivalents, and short-term investments of$377.9 million, and long-term investments and interest receivable of$61.1 million as of December 31, 2025, will be sufficient to fund its operating expenses and capital expenditure requirements through the next twelve months from the date of issuance of these consolidated financial statements.

Basis of Presentation

The accompanying consolidated financial statements of the Company have been prepared in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”) for financial reporting.

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Summary of Significant Accounting Policies

Principles of Consolidation

The accompanying consolidated financial statements include the accounts of Cullinan and consolidated subsidiaries. The Company considers its voting rights, effective economic control, or other control over an entity when evaluating whether to consolidate an entity for financial reporting.

Use of Estimates

The preparation of Cullinan’s consolidated financial statements and accompanying notes in conformity with U.S. GAAP requires the Company’s management to make estimates and judgments that affect the amounts reported in the financial statements. On an ongoing basis, Cullinan’s management evaluates its estimates, which include, but are not limited to, estimates related to prepaid and accrued research and development expenses, equity-based compensation, income taxes, and the fair value of royalty transfer agreements. Management's estimates could change period to period based on changes in facts and circumstances. The Company’s management bases its estimates on historical experience and on other relevant assumptions that are believed to be reasonable. Actual results may differ materially from these estimates.

Concentration of Risk

Cullinan had no significant concentration of credit risk as of December 31, 2025. Cash and cash equivalents are primarily maintained with three financial institutions in the U.S. as of December 31, 2025. Deposits at banks may exceed the federally insured limits. To date, the Company has not experienced any losses on such accounts. Under our investment policy, the Company limits amounts invested in such securities by investment type, credit rating, maturity, industry group and issuer. The goals of our investment policy are (i) safety and preservation of principal and diversification of risk and (ii) liquidity of investments sufficient to meet cash flow requirements.

Cullinan is subject to certain risks and uncertainties and believes that changes in any of the following areas could have a material adverse effect on future financial position or results of operations: ability to conduct and complete preclinical and clinical trials of our current and future product candidates; ability to obtain future financing; ability to build a successful pipeline of product candidates, including efficient expenditures of its resources; regulatory approval and market acceptance of, and reimbursement for, current and future product candidates; protection of Cullinan’s intellectual property, including litigation or claims against the Company based on intellectual property, patent, product, regulatory or other factors; performance of third-party clinical research organizations and manufacturers upon which the Company relies; and Cullinan’s ability to attract and retain employees necessary to support its growth.

The Company is dependent and expects to continue to be dependent on a small number of third-party manufacturers to supply drug product and drug substance for research and development activities in its programs. These programs could be adversely affected by a significant interruption in supply.

Cash and Cash Equivalents

The Company considers all highly liquid investments with original maturities of three months or less at the time of purchase to be cash equivalents. As of December 31, 2025 and 2024, cash equivalents consist of government-backed money market funds.

Investments

Cullinan generally holds investments in marketable securities. Investments not classified as cash equivalents with maturities of less than twelve months are classified as short-term investments in the consolidated balance sheets. Investments with maturities greater than twelve months for which the Company has the intent and ability to hold the investment for greater than twelve months are classified as long-term investments in the consolidated balance sheets.

The amortized cost of marketable securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in interest income. Dividends are also included in interest income. Interest receivable is included in prepaid expenses and other current assets on the consolidated balance sheets and represents accrued and unpaid interest on Cullinan's marketable securities.

The Company periodically reviews its investments for impairment based on a security-specific analysis as of each balance sheet date. If the fair value of a security is below its amortized cost, the Company first assesses whether it intends to sell the security or is more likely than not required to sell it before recovery of its amortized cost. If neither condition is met, the Company evaluates whether a portion of the decline is attributable to credit loss. Any credit-related impairment is recorded as an allowance for credit losses through earnings, with non-credit-related unrealized losses recorded in other comprehensive income (loss).

Fair Value of Financial Instruments

Cullinan has certain financial assets and liabilities recorded at fair value which have been classified as Level 1, 2 or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements. The three levels of the fair value hierarchy are described below:

Level 1—Unadjusted quoted prices for identical assets or liabilities in active markets that the Company has the ability to access;

Level 2—Quoted prices for similar assets and liabilities in active markets or other market-observable inputs such as interest rates, yield curves and foreign currency spot rates; and

Level 3—Pricing or valuations that require inputs that are both significant to the fair value measurement and unobservable.

There were no transfers of financial assets or liabilities measured at fair value between Level 1 and Level 2, and there were no Level 3 investments during 2025 or 2024.

Cullinan's financial assets recorded at fair value consist of investments. The fair value of the Company’s investments is primarily determined using market quotations or prices obtained from independent pricing sources.

Property and Equipment, net

Property and equipment is stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over the estimated useful life of each asset as follows:

Maintenance and repairs that do not improve or extend the life of the assets are expensed when incurred. Upon disposal or retirement of assets, the cost and accumulated depreciation and amortization are removed from the consolidated balance sheets and any resulting gain or loss is reflected in the consolidated statements of operations and comprehensive income (loss).

Leases

Cullinan determines if an arrangement is a lease at inception. A contract is or contains a lease if the contract conveys the right to control the use of an identified asset for a period of time in exchange for consideration. The Company classifies leases at the lease commencement date as operating or finance leases and records a right-of-use asset ("ROU") and a lease liability on the consolidated balance sheets for all leases with an initial lease term of greater than 12 months. Leases with an initial term of 12 months or less are not recorded in the balance sheet, and payments are recognized as expense on a straight-line basis over the lease term.

Cullinan enters into contracts that contain both lease and non-lease components. Non-lease components may include maintenance, utilities and other operating costs. The Company combines the lease and non-lease components of fixed costs in its lease arrangements as a single lease component. Variable costs, such as utilities or maintenance costs, are not included in the measurement of ROU assets and lease liabilities but rather are expensed when the event determining the amount of variable consideration to be paid occurs.

Operating lease assets and liabilities are recognized at the lease commencement date based on the present value of the lease payments over the lease term using the discount rate implicit in the lease. If the discount rate is not readily determinable, Cullinan utilizes an estimate of its incremental borrowing rate based upon the available information at the lease commencement date. Operating lease assets are further adjusted for prepaid or accrued lease payments. Operating lease payments are expensed using the straight-line method as an operating expense over the lease term. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that Cullinan will exercise that option.

Impairment of Long-Lived Assets

Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to future undiscounted net cash flows expected to be generated. Impairment charges are recognized at the amount by which the carrying amount of an asset exceeds the fair value of the asset. Assets to be disposed of are reported at the lower of the carrying amount or the fair value less costs to sell.

Noncontrolling Interests

Noncontrolling interests represent third-party interests in the Company’s subsidiaries. Cullinan determines the amount of the noncontrolling interests in the net assets of the Company’s subsidiaries at each balance sheet date using the hypothetical liquidation at book value ("HLBV") method. Under the HLBV method, the amounts reported as noncontrolling interests in the consolidated balance sheets represent the amounts third parties would hypothetically receive at each balance sheet date under the liquidation provisions of the subsidiaries, assuming the net assets of the subsidiaries were liquidated at their recorded amounts determined in accordance with U.S. GAAP and distributed to the owners of the subsidiaries. Net loss attributable to noncontrolling interests on the consolidated statements of operations and comprehensive income (loss) is determined as the difference in the noncontrolling interest in the consolidated balance sheets between the start and end of each reporting period, after taking into account any capital transactions between the subsidiaries and third parties.

Revenue Recognition

Revenue is recognized when a customer obtains control of promised goods or services. The amount of revenue recognized reflects the consideration to which Cullinan expects to be entitled in exchange for these goods and services. To achieve this core principle, the Company applies the following five steps: 1) identify the customer contract; 2) identify the contract’s performance obligations; 3) determine the transaction price; 4) allocate the transaction price to the performance obligations; and 5) recognize revenue when or as a performance obligation is satisfied.

Licensing arrangements are analyzed to determine whether the promised goods or services, which could include licenses and research and development materials and services, are distinct or whether they must be accounted for as part of a combined performance obligation.

The transaction price is determined based on the consideration to which Cullinan will be entitled. The transaction price may include fixed amounts, variable amounts, or both. The Company reevaluates the probability of realizing such variable consideration and any related constraints at each reporting period. Cullinan includes variable consideration in the transaction price to the extent it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur.

The Company allocates the transaction price based on the estimated standalone selling price of the underlying performance obligations. Cullinan must develop assumptions that require judgment to determine the standalone selling price for each performance obligation identified in the contract. The Company utilizes key assumptions to determine the standalone selling price, which may include other comparable transactions, pricing considered in negotiating the transaction and the estimated costs to complete the respective performance obligation. Cullinan also utilizes judgment in assessing whether or not variable consideration is constrained or if it can be allocated specifically to one or more performance obligations in the arrangement.

When a performance obligation is satisfied, revenue is recognized for the amount of the transaction price allocated to that performance obligation on a relative standalone selling price basis, which excludes estimates of variable consideration that are constrained. Significant management judgment is required in determining the level of effort required under an arrangement and the period over which the Company is expected to complete its performance obligations under an arrangement.

For performance obligations consisting of licenses and other promises, Cullinan utilizes judgment to assess whether the combined performance obligation is satisfied over time or at a point in time and the recognition pattern for the portion of the transaction price allocated to the performance obligation.

Research and development costs are expensed as incurred. Research and development expenses consist primarily of employee compensation costs and amounts incurred with third parties for the provision of services for product candidate development, clinical and preclinical development and related supply and manufacturing costs, and regulatory compliance costs. Advance payments for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are received or services are performed. At the end of each reporting period, the Company conducts a thorough review of ongoing research and development activities to identify goods received or services rendered in order to establish an estimate of the associated costs incurred. The Company compares payments made to its vendors to its estimate of costs incurred to determine the resulting prepaid or accrual position. Significant judgments and estimates are made in determining the prepaid and accrued balances at the end of any reporting period. Such estimates are subject to change as additional information becomes available, and actual results could differ from the Company’s estimates.

Costs incurred to obtain licenses are recognized as research and development expense if the technology licensed has no alternative future use.

Patent Costs

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

Equity-Based Compensation

Equity-based compensation is measured at the grant date for all equity-based awards using the fair value of the awards and is recognized as expense over the requisite service period, which is generally the vesting period. Forfeitures are recognized as they occur. Cullinan classifies equity-based compensation in its consolidated statements of operations and comprehensive income (loss) in the same manner in which the award recipient’s payroll costs or service payments are classified.

The fair value of service-based restricted stock units ("RSUs") is the closing market price of the Company's common stock on the grant date. The fair value of market-based RSUs is measured on the grant date using a Monte Carlo simulation model. Cullinan estimated the fair value of stock options using the Black-Scholes option pricing model. Both the Monte Carlo simulation model and the Black-Scholes option pricing model require the input of objective and subjective assumptions. Certain assumptions used, including the Company’s expected stock price volatility, involve inherent uncertainties and the application of management’s judgment. As a result, if factors change and management uses different assumptions, equity-based compensation expense could be materially different for future awards.

Cullinan recognizes the effect of income tax positions only if those positions are more likely than not of being sustained. Recognized income tax positions are measured at the largest amount of benefit that is greater than fifty percent likely to be realized upon settlement. Changes in measurement are reflected in the period in which the change in judgment occurs.

Net Loss per Share Attributable to Cullinan

Cullinan computes net loss per share attributable to Cullinan using the two-class method required for multiple classes of common stock. The Company has determined that the preferred stock does not have preferential rights over the Company’s common stock and, accordingly, is considered to be a second class of common stock for purposes of calculating net loss per share attributable to Cullinan. Basic net loss per share attributable to Cullinan is calculated by dividing the net loss attributable to Cullinan allocated to each share class by the weighted-average number of shares outstanding during the period for that share class. Diluted net loss per share attributable to Cullinan is determined by dividing net loss attributable to Cullinan allocated to each share class by the weighted-average number of shares outstanding during the period for that share class, adjusted for the dilutive effect of shares of common stock equivalents as determined using the treasury stock method for equity awards and the if-converted method for preferred stock.

Recently Adopted Accounting Pronouncements

In December 2023, the Financial Accounting Standards Board (the “FASB”) issued an accounting standards update to enhance transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. The main provisions in this update require companies to disclose, on an annual basis, specific categories in the rate reconciliation and provide additional information for reconciling items that meet a quantitative threshold. This update also requires companies to disclose, on an annual basis, the amount of income taxes paid, income (or loss) from continuing operations before income tax expense (or benefit), and income tax expense (or benefit) from continuing operations, disaggregated between federal, state and foreign jurisdictions. Cullinan adopted this standard on a retrospective basis effective January 1, 2025 for 2025 annual reporting and interim periods beginning in 2026.

Recently Issued Accounting Pronouncements

In November 2024, the FASB issued an accounting standards to improve disclosures regarding the types of expenses included in commonly presented expense captions, including disaggregating the amounts of employee compensation, depreciation and amortization included within each income statement expense caption. This standard is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027, with early adoption permitted. Cullinan will adopt this standard on January 1, 2027 for 2027 annual reporting and interim periods beginning in 2028 and is evaluating the impact of adopting this standard on its consolidated financial statements and disclosures.

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Financial Instruments

Investments

Cullinan recognized its investments by security type at December 31, 2025 as follows (in thousands):

Cullinan recognized its investments by security type at December 31, 2024 as follows (in thousands):

All of the Company's long-term investments as of each of December 31, 2025 and 2024 had maturities betweenone andtwo years from the respective balance sheet date. The Company did not recognize any credit loss relating to its investments during 2025 or 2024.

Fair Value of Financial Instruments

The following table sets forth the fair value of Cullinan’s financial assets that were measured at fair value on a recurring basis as of December 31, 2025 (in thousands):

The following table sets forth the fair value of Cullinan’s financial assets that were measured at fair value on a recurring basis as of December 31, 2024 (in thousands):

As of December 31, 2025 and 2024, the fair values of cash and cash equivalents, prepaid expenses and other current assets, accounts payable, accrued expenses and other current liabilities approximated their carrying values due to the short-term nature of these instruments.

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Property and Equipment, net

Property and equipment, net consisted of the following as of December 31, 2025 and 2024 (in thousands):

Depreciation expense was $0.3 million in each of 2025 and 2024.

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Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following as of December 31, 2025 and 2024 (in thousands):

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License and Collaboration Agreements

Genrix License Agreement

In June 2025, the Company and Chongqing Genrix Biopharmaceutical Co., Ltd. (“Genrix”) entered into a license agreement (the “Genrix License Agreement”), pursuant to which Genrix granted Cullinan a global (excluding mainland China, Hong Kong, Macau and Taiwan), exclusive license to develop and commercialize velinotamig, a BCMAxCD3 bispecific T cell engager, in all fields of use.

Under the terms of the Genrix License Agreement, Cullinan paid Genrix an upfront license fee of $20.0 million. Genrix will be eligible to receive up to $292.0 million in milestone payments based on the achievement of certain clinical and regulatory milestones. Genrix is also eligible to receive up to an additional $400.0 million in net sales-based milestones as well as tiered royalties ranging from mid-single digit to mid-teens, as a percentage of net sales of licensed products.

Unless earlier terminated, the Genrix License Agreement will continue in effect on a country-by-country basis until the expiration of Cullinan’s royalty obligations in such country. The Genrix License Agreement may be terminated by either party for a material breach by the other party, subject to notice and cure provisions, or in the event of the other party’s insolvency. Additionally, subject to a notice period, Cullinan may terminate the Genrix License Agreement for convenience. In the Genrix License Agreement, each party made customary representations and warranties and agreed to customary covenants, including, without limitation, with respect to indemnification, for transactions of this type.

Cullinan evaluated the Genrix License Agreement and determined that the exclusive license to develop and commercialize velinotamig represented an asset acquisition of in-process research and development. The Company also determined that the asset had no alternative future use at the time of acquisition, and therefore, the upfront license fee of $20.0 million was recorded within research and development expenses in 2025.

Taiho Agreements

Cullinan has a co-development agreement with an affiliate of Taiho Pharmaceutical Co., Ltd ("Taiho"), pursuant to which the Company is collaborating to develop zipalertinib for the treatment of a genetically defined subset of patients with NSCLC, and Taiho will commercialize zipalertinib. For the agreed-upon indication, Cullinan and Taiho share development costs equally, and each party will receive 50% of any future pre-tax profits from potential U.S. sales of zipalertinib. For any additional indications that Taiho chooses to develop independently, Taiho will bear all development costs until they have sufficient data from such indication to support a commercial purpose or submission of zipalertinib for such indication. At such time,50% of Taiho’s independent development costs, subject to certain adjustments, will be deducted from future pre-tax profits for potential U.S. sales of zipalertinib. In November 2025, Taiho independently initiated an ongoing global Phase 3 clinical trial evaluating zipalertinib in an additional indication.

The Company concluded that the co-development agreement with Taiho is a collaborative arrangement because Cullinan is an active participant in the development of zipalertinib, and in the oversight of commercialization for zipalertinib. Amounts due to or from Taiho for zipalertinib development activities after the execution of the co-development agreement are recorded within research and development expenses or general and administrative expenses based on the nature of the activity. The following table summarizes each party’s respective share of costs incurred and paid by the other party for zipalertinib development activities for 2025 and 2024 (in thousands):

Under a separate agreement, Cullinan is also eligible to receive up to $130.0 million from Taiho tied to epidermal growth factor receptor exon 20 non-small-cell lung cancer U.S. regulatory milestones. As of December 31, 2025, no milestone payments have been received under this agreement.

DKFZ/Tübingen License Agreement

The Company has exclusive worldwide rights to CLN-049, its bispecific T cell engager targeting FLT3 and CD3, pursuant to an exclusive license agreement (the "DKFZ/Tübingen License Agreement") with Deutsches Krebsforschungszentrum ("DKFZ"), Eberhard Karls University of Tübingen, Faculty of Medicine, and Universitätsmedizin Gesellschaft für Forschung und Entwicklung mbH, Tübingen. Pursuant to the DKFZ/Tübingen License Agreement, DKFZ and the University of Tübingen, collectively referred to as the Licensor, granted to Cullinan an exclusive worldwide, milestone- and royalty-bearing license under certain licensed patent rights, applications, technical information and know-how, with the right to grant sublicenses through multiple tiers to research, develop, commercialize or otherwise exploit licensed products within the field.

The Company shall pay certain non-refundable, non-creditable milestone payments to the Licensor upon the occurrence of certain clinical and regulatory events related to a licensed product. Each milestone payment is paid one time only up to a certain payment amount.

Furthermore, Cullinan is required to pay running low to mid-single digit royalty percentage on net sales of each licensed product on a country-by-country and product-by-product basis during the royalty term, subject to certain offsets or reductions. The aggregate, worldwide royalties due to Licensor for net sales of any licensed product in a calendar year shall not be reduced to an amount less than low to mid-single digit percentages. Such royalty obligations will expire on a country-by-country and product-by-product basis upon the later of (a) the expiration of the last valid claim of a patent which covers a product in such country and (b) a low double digit anniversary following the first commercial sale of a product in such country. Under certain conditions upon a first change in control in the Company's CLN-049 development subsidiary, Cullinan shall pay a non-refundable, non-creditable mid-single digit percent of sale proceeds, provided, however, that such payment shall not be required following consummation of an initial public offering of the Company's CLN-049 development subsidiary.

Either party may terminate the agreement upon a material breach by the other party or insolvency of the other party. Cullinan may terminate the DKFZ/Tübingen License Agreement for any or no reason after the first filing of an investigational new drug application or clinical trial agreement by providing prior written notice. Licensor may terminate the agreement by providing prior written notice, if the Company or any of its affiliates challenges the validity of certain patent rights. Unless earlier terminated, the DKFZ/Tübingen License Agreement continues perpetually. As of December 31, 2025, no milestone obligations have been incurred under the DKFZ/Tübingen License Agreement.

Adimab

Cullinan has a collaboration agreement with Adimab, LLC ("Adimab") (the "Adimab Collaboration Agreement"). Pursuant to the Adimab Collaboration Agreement, the Company selected a single-digit number of biological targets against which Adimab used its proprietary platform technology to discover and/or optimize antibodies, including antibody components that were used to generate CLN-978, based upon mutually agreed-upon research plans. Under the Adimab Collaboration Agreement, Cullinan has the ability to select additional biological targets against which Adimab will provide additional antibody discovery and optimization services for delivery of binders with a specified range of binding affinities.

During the research term and evaluation term for a given research program with Adimab, the Company has a non-exclusive worldwide license under Adimab’s technology to perform certain research activities and to evaluate the program antibodies to determine whether Cullinan wants to exercise its option to obtain a royalty-free, fully paid, non-exclusive license to exploit such antibodies and sublicense through multiple tiers (the "Adimab Option").

Under the Adimab Collaboration Agreement, Cullinan paid a one-time, non-creditable, non-refundable technology access fee. Cullinan is also required to pay an annual access fee and research funding fees, which are creditable against the annual access fee for Adimab’s performance of its’ research obligations under the Adimab Collaboration Agreement. Cullinan is also obligated to make certain research delivery, clinical and sales milestone payments to Adimab in an aggregate amount of up to $15.8 million for each product, on a product-by-product basis, subject to certain reductions and discounts. As of December 31, 2025, Cullinan has incurred and paid a cumulative$0.5 million of milestone obligations for CLN-978 under the Adimab Collaboration Agreement.

Cullinan is obligated to pay certain royalty payments on a product-by-product basis at a low single-digit percentage of annual aggregate worldwide net sales. Such royalty obligations will expire on a country-by-country and product-by-product basis upon the later of (a) a certain low double-digit number of years after the first commercial sale of such product in such country and (b) the expiration of the last issued and not expired, permanently revoked, or invalid claim within a program patent covering such product.

Cullinan may terminate the Adimab Collaboration Agreement at any time, for any reason, upon a specified period advance written notice. The term of the Adimab Collaboration Agreement expires upon the last research program’s evaluation term in the event no Adimab Option is exercised or in the event an Adimab Option is exercised, after the royalty term expires at the later of a specified period or invalid patent coverage of the relevant product.

During 2025 and 2024, Cullinan didnot incur any milestone obligations under the Adimab Collaboration Agreement.

Massachusetts Institute of Technology

The Company had an exclusive patent license agreement (the "MIT License Agreement") for the technology underlying CLN-617 with MIT through its development subsidiary, Cullinan Amber Corp. ("Cullinan Amber"). Under the terms of the MIT License Agreement, Cullinan has incurred and paid $0.7 million of milestone obligations through December 31, 2025. In November 2025, after a review of the emerging clinical data in patients with advanced solid tumors, Cullinan decided not to pursue further development of CLN-617. In connection with the decision not to pursue further development of CLN-617, the Company notified MIT of its decision to terminate the MIT License Agreement. In connection with the termination of the MIT License Agreement, Cullinan returned the licensed patent rights for the technology underlying CLN-617 to MIT.

During 2025 and 2024, Cullinan didnot incur any milestone obligations under the MIT License Agreement.

Harbour License Agreement

The Company and Harbour BioMed US Inc. (“Harbour”) were party to a license and collaboration agreement pursuant to which Harbour granted Cullinan an exclusive license for the development, manufacturing and commercialization of HBM7008 (CLN-418) in the U.S. In August 2024, following a review of the data from the Phase 1 clinical trial of CLN-418, the Company notified Harbour of its decision to terminate the license and collaboration agreement, effective November 2024. In connection with the termination, the Company discontinued development of CLN-418 and returned development and commercial rights for CLN-418 to Harbour.

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Stockholders' Equity

Common Stock

Each share of common stock entitles the holder to one vote and to receive dividends when and if declared by the board of directors of the Company. No dividends have been declared through December 31, 2025.

2024 Private Placement

In April 2024, Cullinan completed a private placement (the "2024 Private Placement") in which Cullinan issued approximately 14.4 million shares of its common stock and pre-funded warrants to purchase approximately 0.3 million additional shares of its common stock. Cullinan received net proceeds of $262.7 million from the 2024 Private Placement, after deducting offering costs of $17.3 million. Refer to the discussion under the heading “Warrants” below for further detail regarding the pre-funded warrants.

At-the-Market Equity Offering Program

Cullinan has an at-the-market equity offering program (the “ATM") through an agreement with Cowen and Company, LLC ("Cowen") pursuant to which the Company may offer and sell up to $125.0 million of its common stock from time to time through Cowen, acting as its sales agent. The Company made no sales under the ATM in 2025. Through December 31, 2025, the Company has sold approximately 3.3 million shares under the ATM and received net proceeds of $38.4 million after deducting commissions. As of December 31, 2025, Cullinan had $85.6 million in shares of its common stock remaining under the ATM.

Preferred Stock

Each share of preferred stock is convertible into ten shares of common stock at the option of the holder at any time, subject to certain limitations, including that the holder is prohibited from converting preferred stock into common stock if, as a result of such conversion, the holder, together with its affiliates, would beneficially own a number of shares of common stock more than 9.99% of the total common stock then issued and outstanding immediately following the conversion of such shares of preferred stock. Holders of the preferred stock are permitted to increase this percentage to an amount not to exceed 19.99% upon 60 days notice.

Shares of preferred stock generally have no voting rights, except as required by law and except that the consent of a majority of the holders of the outstanding preferred stock will be required to amend the terms of the preferred stock. In the event of the Company’s liquidation, dissolution or winding up, holders of preferred stock will participate pari passu with any distribution of proceeds to holders of common stock. Holders of preferred stock are entitled to receive when, as, and if dividends are declared and paid on the common stock, an equivalent dividend, calculated on an as-converted basis. Shares of preferred stock are otherwise not entitled to dividends.

The preferred stock ranks (i) senior to any class or series of capital stock of Cullinan created specifically ranking by its terms junior to the preferred stock; (ii) on parity with the common stock and any class or series of capital stock of the Company created specifically ranking by its terms on parity with the preferred stock; and (iii) junior to any class or series of capital stock of Cullinan created specifically ranking by its terms senior to any preferred stock, in each case, as to distributions of assets upon liquidation, dissolution or winding up of the Company, whether voluntarily or involuntarily.

The Company determined that the preferred stock should be classified as permanent equity.

Noncontrolling Interests in Subsidiaries

Certain of the Company's current and former clinical-stage product candidates are held through development subsidiaries in which the Company has controlling interests. The following table shows the Company’s ownership interest as of December 31, 2025 and 2024, respectively, in product candidates in which the Company has a controlling interest:

During 2024, Cullinan paid $4.4 million to acquire shares and options to purchase shares of its CLN-619 development subsidiary that were held by noncontrolling interests.

Warrants

In April 2025, all outstanding pre-funded warrants were exercised on a cashless basis in exchange for 0.3 million shares of common stock.

Cullinan determined that the pre-funded warrants should be equity-classified when they were issued. The Company also determined that the pre-funded warrants should be included in the weighted-average shares used in computing basic net loss per share attributable to common stockholders of Cullinan.

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Equity-Based Compensation

The Company recorded equity-based compensation in the following expense categories in the consolidated statements of operations and comprehensive income (loss) in 2025 and 2024 (in thousands):

2021 Stock Option and Incentive Plan

Cullinan grants equity awards in the form of stock options and RSUs to its employees and non-employees directors, through the 2021 Stock Option and Incentive Plan (the "2021 Stock Plan"). Cullinan has also granted equity awards outside of the 2021 Stock Plan in the form of stock options as an inducement material to an individual's entering into employment with the Company. As of December 31, 2025, there were approximately 2.1 million shares remaining for future grants under the 2021 Stock Plan.

The 2021 Stock Plan provides that the number of shares reserved and available for issuance under the 2021 Stock Plan will automatically increase each January 1 by 5% of the outstanding number of shares of Cullinan’s common stock on the immediately preceding December 31 or such lesser number of shares as determined by Cullinan’s board of directors or compensation committee. On January 1, 2026, the total number of shares available for issuance under the 2021 Stock Plan increased by approximately 3.0 million shares under this provision.

The options granted have aten-year term and were issued with an exercise price equal to the closing market price of Cullinan’s common stock on the grant date. For equity awards with service-based vesting conditions, Cullinan recognizes compensation expense over the vesting period, which is generally over afour-year period. For equity awards with a market-based vesting condition, the Company recognizes compensation expense over the requisite service period. The number of shares awarded, if any, when a market-based award vests will depend on the degree of achievement of the corporate stock price metrics within the performance period of the award.

Determining Fair Value of Options

The fair value of options is estimated using the Black-Scholes option pricing model, which takes into account inputs such as the exercise price, the value of the underlying common stock at the grant date, expected term, expected volatility, risk-free interest rate and dividend yield. The fair value of each grant of options during 2025 and 2024 were determined using the methods and assumptions discussed below:

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The expected term of options is determined using the “simplified” method, as prescribed in the SEC Staff Accounting Bulletin (SAB) No. 107, whereby the expected life equals the arithmetic average of the vesting term and the original contractual term of the option due to Cullinan’s lack of sufficient historical data.

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The risk-free interest rate is based on implied yields available from U.S. Treasury securities with a remaining term equal to the expected term assumed at the grant date.

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The expected volatility used in the Black-Scholes option pricing model for new options was based on a blended rate that combines the Company’s historical volatility with the historical volatilities of the stock prices of similar entities within Cullinan’s industry over a period of time commensurate with the expected term assumption.

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The estimated annual dividend yield was based on the Company’s expectation of not paying dividends on its common stock in the foreseeable future.

For 2025 and 2024, the weighted-average grant date fair value of the options granted were $6.01 and$12.28 per share, respectively. The grant date fair value was estimated at the time of grant using the Black-Scholes option-pricing model using the following weighted-average assumptions in 2025 and 2024:

Stock Options

The following table summarizes 2025 stock option activity (options and aggregate intrinsic value in thousands):

As of December 31, 2025, there was $36.1 million in unrecognized compensation costs that are expected to be recognized over a remaining weighted-average period of 2.4 years.

The aggregate intrinsic value of options is calculated as the difference between the exercise price of the options and the fair value of Cullinan’s common stock for those options that had exercise prices lower than the fair value of the Company’s common stock at the measurement date. The total intrinsic value of options exercised in 2025 and 2024 was $0.1 million and$10.4 million, respectively.

RSUs

The following table summarizes the activity related to RSUs during 2025 (shares in thousands):

(1)

The number outstanding represents the number of shares issuable upon vesting of service-based and market-based RSUs, assuming the Company achieves its corporate stock price metrics at the target achievement level.

As of December 31, 2025, there was $15.5 million in unrecognized compensation cost related to RSUs expected to be recognized over a remaining weighted-average period of 2.6 years. The total fair value of RSUs that vested during 2025 and 2024 was $3.4 million and $2.9 million, respectively.

2021 Employee Stock Purchase Plan

The 2021 Employee Stock Purchase Plan (the "ESPP") authorizes the issuance of shares of common stock to participating eligible employees and provides for two six-month offering periods each year. As of December 31, 2025, there were approximately 2.1 million shares remaining for future purchases under the ESPP.

The ESPP provides that the number of shares reserved and available for issuance under the ESPP will automatically increase each January 1 by the lesser of 0.8 million shares of the Company's common stock,1% of the outstanding number of shares of Cullinan’s common stock on the immediately preceding December 31, or such lesser number of shares as determined by the Company’s compensation committee. On January 1, 2026, the total number of shares available for issuance under the ESPP increased by approximately 0.6 million shares under this provision.

During each of 2025 and 2024, Cullinan issued less than 0.1 million shares of its common stock pursuant the ESPP.

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Royalty Transfer Agreements

The Company's CLN-049 development subsidiary is party to royalty transfer agreements with two charitable foundations. Under these royalty transfer agreements, the charitable foundations are collectively entitled to receive a low single digit royalty percentage of all global net sales of any products developed by the development subsidiary, subject to limitations after patent expirations and on intellectual property developed after a change of control. Cullinan has deemed these royalty transfer agreements to be freestanding financial instruments that should be accounted for at fair value. The Company concluded that these instruments had no value at the inception of the agreements.

Cullinan has not had any applicable net sales from its products and as a result, hasnot paid or incurred any royalties under these agreements as of December 31, 2025. Given the early-stage nature of the underlying technologies and inherent risks associated with obtaining regulatory approval and achieving commercialization, the Company ascribed no value to the royalty transfer agreements as of December 31, 2025 and 2024.

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Cullinan didnot record income tax expense or benefit in 2025 due to its net loss before income taxes in the current year and expected losses in future years. During 2024, the Company recorded a current federal income tax expense of $0.1 million. The income tax expense recorded for 2024 was driven by the finalization of the federal research and development credits generated during 2023 that were carried back to tax year 2022. The Company’s net loss before income taxes consists solely of domestic losses in each of 2025 and 2024. As of December 31, 2024, Cullinan had recorded $3.0 million within prepaid expenses and other current assets on its consolidated balance sheets for the Company’s tentative refund from the carryback of 2023 federal research and development credits to tax year 2022.

During 2025, Cullinan was refunded $3.0 million for federal income taxes from the carryback of 2023 federal research and development credits to tax year 2022. During 2024, Cullinan paid $1.6 million for federal income taxes due to a refund payment from the Internal Revenue Service (the "IRS") that was in excess of the Company’s 2022 federal refund claim and was refunded $3.9 million for Massachusetts state income taxes from 2022 state refund claims.

A reconciliation of the Company’s statutory income tax rate to its effective income tax rate in 2025 and 2024 is as follows:

(1) Massachusetts makes up the majority (greater than 50 percent) of the State taxes, net of federal benefit category.

As of December 31, 2025 and 2024, the net deferred income tax asset balance related to the following (in thousands):

The Company's net operating loss ("NOL") and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service ("IRS")and state tax authorities. Under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, as well as similar state provisions, NOL and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant stockholders over a three-year period in excess of 50%. The rules generally operate by focusing on changes in ownership among stockholders considered by the rules as owning, directly or indirectly, 5% or more of the stock of a company and any change in ownership arising from new issuances of stock by the company.

As of December 31, 2025 and 2024, the Company had federal NOL carryforwards, of $312.6 million and $125.3 million, respectively, which may be available to offset future income tax liabilities. As of December 31, 2025, $311.2 million of Cullinan's federal NOL carryforwards can be carried forward indefinitely, and the remaining $1.4 million expires in 2037. As of December 31, 2025 and 2024, the Company had state NOL carryforwards of $317.7 million and $128.2 million, respectively, which may be available to offset future income tax liabilities. As of December 31, 2025, Cullinan's state NOL carryforwards begin to expire in 2031.

As of December 31, 2025 and 2024, the Company had federal research and development tax credit carryforwards of $8.7 million and $5.4 million, respectively. As of December 31, 2025, Cullinan’s federal research and development tax credit carryforwards begin to expire in 2036. As of each of December 31, 2025 and 2024, the Company had state research and development tax credit carryforwards of $2.7 million and $2.0 million, respectively. As of December 31, 2025, $0.3 million of Cullinan's state research and development tax credit carryforwards can be carried forward indefinitely, and the remaining $2.4 million expires beginning in 2036.

Cullinan has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets, which primarily consist of capitalized research and development costs, temporary differences on equity-based compensation, and NOL carryforwards. The Company has considered its history of cumulative net losses, estimated future taxable income and prudent and feasible tax planning strategies and has concluded that it is more likely than not that Cullinan will not realize the benefits of its deferred tax assets. As a result, as of December 31, 2025, the Company has maintained a full valuation allowance against its remaining net deferred tax assets.

Cullinan’s valuation allowance increased in 2025 primarily due to the valuation allowance on NOLs generated during the year and in 2024 primarily due to the valuation allowance on capitalized research and development costs and NOLs generated during the year. The following table summarizes activity in Cullinan’s valuation allowance during 2025 and 2024 (in thousands):

The calculation of the Company’s tax liabilities involves dealing with uncertainties in the application of complex tax laws and regulations for both federal taxes and the states in which Cullinan operates or does business in.

The Company recognizes a tax benefit from an uncertain tax position when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, on the basis of the technical merits. Cullinan records uncertain tax positions as liabilities and adjusts these liabilities when its judgment changes as a result of the evaluation of new information not previously available. Due to the complexity of some of these uncertainties, the ultimate resolution may result in a payment that is materially different from the Company’s current estimate of the unrecognized tax benefit liabilities. These differences will be reflected as increases or decreases to income tax expense in the period in which new information is available. As of December 31, 2025 and 2024, Cullinan hasnot recorded a liability for any uncertain tax positions in its consolidated financial statements.

The Company recognizes interest and penalties related to unrecognized tax benefits on the income tax expense line in the accompanying consolidated statements of operations and comprehensive income (loss). As of December 31, 2025 and 2024, no accrued interest or penalties are included in the consolidated balance sheets.

Cullinan files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions in the U.S. There are currently no pending tax examinations. Cullinan's federal and state income tax returns are generally subject to tax examinations for tax years 2022 and later. To the extent that the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the IRS and the state tax authorities to the extent utilized in a future period.

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Commitments and Contingencies

The Company enters into contracts in the normal course of business with contract research organizations, contract manufacturing organizations, and other third parties for preclinical research studies, clinical trials and testing and manufacturing services. These agreements generally include cancellation clauses.

Indemnification Agreements

In the ordinary course of business, Cullinan may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and executive officers that will require Cullinan, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in certain cases, unlimited. To date, Cullinan has not incurred any material costs as a result of such indemnifications. The Company is not aware of any indemnification arrangements that could have a material effect on its financial position, results of operations or cash flows, and it hasnot accrued any liabilities related to such obligations in its consolidated financial statements as of December 31, 2025 and 2024.

Legal Proceedings

Cullinan is not currently party to, or aware of, any material legal proceedings. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. Cullinan expenses as incurred the costs related to such legal proceedings.

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Leases

Cullinan has an operating lease for approximately 14,000 square feet of office space in a multi-tenant building in Cambridge, Massachusetts, which commenced in August 2022 and was scheduled to expire in July 2026. In October 2025, Cullinan extended its operating lease through September 2028. Cullinan determined that the lease extension constituted a modification of the existing lease, which required remeasurement of the lease liability and a corresponding adjustment to the right-of-use-asset. Lease expense consisted of operating lease costs of $1.2 million for each of 2025 and 2024.

The following table summarizes supplemental cash flow information for 2025 and 2024 (in thousands):

The following table summarizes Cullinan’s future minimum lease payments as of December 31, 2025 (in thousands):

The following table summarizes the weighted-average lease term and discount rate as of December 31, 2025 and 2024:

As Cullinan’s operating leases did not provide an implicit rate, the Company used its incremental borrowing rate based on the information available in determining the present value of lease payments. Cullinan’s incremental borrowing rate was based on the term of the lease, the economic environment and reflects the rate the Company would have had to pay to borrow on a secured basis.

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Net Loss per Share Attributable to Cullinan

The Company computes net loss per share attributable to Cullinan for its common stock and preferred stock using the two-class method required for multiple classes of common stock. The two-class method is an earnings (loss) allocation method under which earnings (loss) per share is calculated for each class of common stock.

The following table sets forth the calculation of basic and diluted net loss per share attributable to Cullinan for 2025 and 2024 (in thousands, except per share data):

Cullinan used the treasury stock method for equity awards and the if converted method for preferred stock to determine the number of dilutive shares outstanding in each period. The following table sets forth potential common shares that were excluded from the computation of diluted net loss per share attributable to common stockholders of Cullinan for 2025 and 2024 because their effect would have been anti-dilutive (in thousands):

(14)

Segment Reporting

The Company operates and manages the business asone reporting andone operating segment, which is the business of developing immunology and oncology therapies. Cullinan has determined that its Chief Executive Officer is the chief operating decision maker ("CODM"). Cullinan’s CODM reviews financial information on an aggregate basis and uses net loss attributable to Cullinan as presented in the consolidated statement of operations and comprehensive income (loss) for purposes of allocating resources and evaluating financial performance.

Financial information of the Company’s reportable segment for 2025 and 2024 are as follows (in thousands):

(1)

Other segment expenses for 2025 and 2024 include legal fees relating to patent and corporate matters; professional fees for accounting, auditing, tax, and administrative consulting services; insurance costs; marketing expenses; depreciation; and other operating costs.

All of the Company’s long-lived assets were located in the U.S. as of each of December 31, 2025 and 2024. Expenditures for additions to long-lived assets included purchases of property and equipment for 2025. There wereno expenditures for long-lived assets in 2024.

EXHIBIT INDEX

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this Report to be signed on its behalf by the undersigned, thereunto duly authorized.

POWER OF ATTORNEY

Each person whose individual signature appears below hereby authorizes and appoints Nadim Ahmed and Mary Kay Fenton, and each of them, with full power of substitution and resubstitution and full power to act without the other, as his or her true and lawful attorney-in-fact and agent to act in his or her name, place and stead and to execute in the name and on behalf of each person, individually and in each capacity stated below, and to file any and all amendments to this annual report on Form 10-K and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing, ratifying and confirming all that said attorneys-in-fact and agents or any of them or their or his substitute or substitutes may lawfully do or cause to be done by virtue thereof.

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, this Report has been signed below by the following persons on behalf of the Registrant in the capacities and on the dates indicated.