ALUMIS INC. Commitments Disclosure

9.Commitments and Contingent Liabilities

Operating Leases

In August 2022, the Company entered into a lease agreement for 55,000 square feet of office and laboratory space in South San Francisco, California, which commenced in January 2023 and has a contractual termination date in August 2033. The lease agreement includes a renewal option allowing the Company to extend this lease for an additional three years at the prevailing rental rate, which the Company was not reasonably certain to exercise.

In December 2024, the Company entered into a lease agreement for approximately 22,000 square feet of additional office space in South San Francisco, California. The lease has a contractual termination date of December 2026, with the right to extend the lease for an additional two years subject to certain conditions. The Company determined that, for accounting purposes, the commencement date of the lease is in January 2025 and the lease term ends in December 2026, as it was not reasonably certain that the lease would be extended. As of the commencement date, future lease payments totaled $1.9 million and the lease liability was calculated to be $1.8 million, which is equal to the present value of the future lease payments, discounted at an incremental borrowing rate of 7.9%.

Upon the closing of the ACELYRIN Merger, the Company became the successor to ACELYRIN’s rights under ACELYRIN’s lease and sublease agreements. In January 2023, ACELYRIN entered into a lease agreement to rent approximately 10,012 square feet of office space in Southern California. The term of the lease is 65 months with an option to extend it for an additional three years. Monthly rent payments are approximately $30,500, subject to an annual 3.0% increase. In addition to the base rent, the Company is obligated to pay variable costs related to its share of operating expenses and taxes. In December 2025, the Company entered into an agreement to sublease the entirety of its Southern California leased space through August 24, 2028, the remainder of the lease term. The sublease included the operating lease right-of-use asset and certain property, plant and equipment. Sublease income was immaterial for the year ended

December 31, 2025.

In July 2023, ACELYRIN entered into a lease agreement to rent approximately 22,365 square feet of office space in South San Francisco, California. The term of the lease is 60 months with an option to extend it for an additional five years. Monthly base rent payments are approximately $150,000, subject to an annual 3.5% increase. In February 2025, ACELYRIN entered into an agreement to sublease the entirety of its South San Francisco leased space through October 2029, the remainder of the lease term. The sublease included the operating lease right-of-use asset and certain property, plant and equipment. Sublease income was immaterial for the year ended December 31, 2025.

The components of lease costs were as follows (in thousands):

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Supplemental cash flow information related to the operating leases were as follows (in thousands):

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Weighted-average remaining lease term and incremental borrowing rate for the operating leases were as follows:

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Future minimum lease payments under non-cancelable leases as of December 31, 2025 were as detailed below (in thousands):

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FronThera Contingent Consideration

In March 2021, the Company entered into the FronThera Acquisition, and the transaction was accounted for as an asset acquisition. Under the stock purchase agreement, the Company is obligated to pay contingent consideration of up to an aggregate of $120.0 million based on the achievement of specified clinical and approval milestones, including receipt of first commercialization approval in the United States or certain other jurisdictions, of up to an aggregate of $70.0 million payable for clinical milestones, and of up to an aggregate of $50.0 million payable for approval milestones, all related to technology acquired under the agreement. In the year ended December 31, 2022, the Company incurred and made a $37.0 million milestone payment for the first administration of envu to a patient enrolled in a Phase 2 clinical trial of envu, which

was recorded in research and development expenses in the consolidated statements of operations and comprehensive loss. In July 2024, the Company met a milestone in connection with the first administration of envu to a patient enrolled in a Phase 3 clinical trial of envu and made a $23.0 million milestone payment in August 2024, which was recorded in research and development expenses in the consolidated statements of operations and comprehensive loss for the year ended December 31, 2024. No other milestones were achieved or were probable of being achieved as December 31, 2025.

License and Commercialization Agreement with Pierre Fabre

Upon the closing of the ACELYRIN Merger, the Company became the successor to ACELYRIN’s rights under the March 25, 2021 license and commercialization agreement with Pierre Fabre Medicament SAS (“Pierre Fabre”), as amended (the “Pierre Fabre Agreement”), through which ACELYRIN received certain exclusive worldwide licenses with the right to sublicense certain patents, know-how and other intellectual property to develop, manufacture, use and commercialize lonigutamab for non-oncology therapeutic indications. The license from Pierre Fabre extends to any product containing lonigutamab (excluding any fragments or derivatives) as its sole active ingredient (each, a “PF Licensed Product”). The Pierre Fabre Agreement prohibits the Company from using the licensed intellectual property in any antibody drug conjugate, multi-specific antibodies or any other derivatives of lonigutamab.

The Company is obligated to (i) make payments of up to $100.5 million upon the achievement of various development and regulatory milestones, (ii) make milestone payments of up to $390.0 million upon the achievement of certain commercial milestones, and (iii) pay tiered royalties in the high single-digit to low-teen percentages to Pierre Fabre on worldwide net sales in a given calendar year. Royalties will be payable for each PF Licensed Product in a given country during a period commencing upon the first commercial sale of such PF Licensed Product in such country and continuing until the latest of (a) 10 years after such first commercial sale, (b) expiration of last-to-expire valid claim in a licensed patent in such country and (c) expiration of regulatory exclusivity for such PF Licensed Product in such country. In the event the Company enters into a sublicense with a third party, the Company must also share with Pierre Fabre a percentage of any revenues from option fees, upfront payments, license maintenance fees, milestone payments or the like generated from the sublicense. Such percentage may be between the high single-digits to the low thirties based on which stage of development of a PF Licensed Product the sublicense relates to.

Unless earlier terminated, the Pierre Fabre Agreement will continue on a PF Licensed Product-by-PF Licensed Product and country-by-country basis until there are no more royalty payments owed to Pierre Fabre on any PF Licensed Product thereunder. Either party may terminate the Pierre Fabre Agreement upon an uncured material breach, or upon the bankruptcy or insolvency of the other party. Pierre Fabre may also terminate the agreement if the Company or any of its affiliates institutes a patent challenge against the licensed patents from Pierre Fabre. The Company may also terminate the Pierre Fabre Agreement with or without cause upon nine months’ prior written notice, so long as there is no ongoing clinical trial for any PF Licensed Product.

As of December 31, 2025, no milestones were probable and accrued in the consolidated balance sheets.

Purchase Commitments

The Company enters into various agreements in the ordinary course of business, such as those with suppliers, CROs, CMOs and clinical trial sites. Upon the closing of the ACELYRIN Merger, the Company became the successor to contracts with non-cancellable commitments under ACELYRIN contracts. The total value of non-cancellable purchase commitments under contracts was $1.6 million as of December 31, 2025. This presentation of non-cancellable purchase commitments does not include any estimates of potential reduction of such liabilities related to mitigation obligations of the counterparties in the event of cancellation under the terms of its engagements.

Legal Contingencies

From time to time, the Company has and may become involved in legal proceedings arising in the ordinary course of business, any or all of which could have a material adverse impact on the Company, including its financial position. The

outcomes of legal proceedings are not within the Company’s complete control and may not be known for prolonged periods of time. The Company records a liability for such matters when it is probable that future losses will be incurred and that such losses can be reasonably estimated. Significant judgment by the Company is required to determine both probability and the estimated amount. Legal costs related to these matters, including attorney fees, are expensed as incurred and are recorded as general and administrative expenses in the consolidated statements of operations and comprehensive loss.

On November 15, 2023, a purported federal securities class action lawsuit was commenced in the United States District Court for the Central District of California. On February 15, 2024, the Court appointed joint lead plaintiffs and lead counsel. An amended complaint was filed on March 26, 2024 (Boukadoum v. Acelyrin, Inc. et al., No. 2:23-cv-09672-FMO-MAA), naming ACELYRIN and then-current and former executive officers and directors as defendants. The complaint alleges that the defendants violated the Exchange Act and Securities Act by misleading investors about the Phase 2b trial of izokibep in hidradenitis suppurativa. The original complaint was filed following ACELYRIN’s announcement of the week 16 results from the Part B portion of such Phase 2b trial. The amended complaint seeks damages and an award of reasonable costs and expenses, including attorneys’ fees, expert fees and other costs, as well as such other and further relief as the court may deem just and proper. On May 3, 2024, the defendants filed their motion to dismiss the amended complaint, which was granted by the court, with leave to amend, in January 2026. On February 5, 2026, the plaintiffs filed a second amended complaint, which seeks damages and an award of reasonable costs and expenses, as well as such other and further relief as the court may deem just and proper. On February 19, 2026, the defendants filed their motion to dismiss the second amended complaint, which remains pending.

It is possible that additional suits will be filed, or allegations made by stockholders, with respect to these same or other matters and also naming the Company and/or its officers and directors as defendants. This lawsuit and any other potential lawsuits are subject to inherent uncertainties, and the actual defense and disposition costs will depend upon many unknown factors. The outcome of this lawsuit is necessarily uncertain. The Company could be forced to expend significant resources in the defense against this and any other related lawsuits and the Company may not prevail. The Company currently is not able to estimate the possible loss to the Company from this lawsuit, as this lawsuit is currently at an early stage, and such amounts could be material to the Company’s financial statements even if the Company prevails in the defense against this lawsuit. The Company cannot be certain how long it may take to resolve this lawsuit or the possible amount of any damages that the Company may be required to pay. As of December 31, 2025, the Company did not consider any payment to be probable or reasonably estimable and had not accrued for any potential liability relating to this lawsuit.

Guarantees and Indemnifications

In the normal course of business, the Company enters into agreements that contain a variety of representations and provide for general indemnification. Its exposure under these agreements is unknown because it involves claims that may be made against the Company in the future. To the extent permitted under Delaware law, the Company has agreed to indemnify its directors and officers for certain events or occurrences while the director or officer is, or was serving, at a request in such capacity. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. As of December 31, 2025 and 2024, the Company did not have any material indemnification claims that were probable or reasonably possible and consequently has not recorded related liabilities.