ALUMIS INC. Revenue Disclosure

7.Revenue

Kaken Collaboration Agreement

On March 25, 2025, (the “Effective Date”) the Company entered into the Kaken Collaboration Agreement. Under the terms of the Collaboration Agreement, the Company granted to Kaken an exclusive right to develop, manufacture and commercialize envu, formerly known as ESK-001, for dermatology indications in Japan, with options to expand the license, subject to opt-in payments and certain cost-sharing obligations on the part of Kaken, to include rheumatological and gastrointestinal diseases.

Pursuant to the terms of the Collaboration Agreement, the Company is responsible for the global development of envu in the dermatology field, and Kaken is responsible for the clinical development, regulatory approvals and commercialization of envu in Japan in dermatology and other indications for which Kaken has exercised its option. Kaken is required to use commercially reasonable efforts to conduct all subsequent development, manufacture, and commercialization activities. The Collaboration Agreement further provides that the Company will retain rights to envu in all other indications and geographies.

In March 2025, Kaken made an upfront, non-refundable payment of $20.0 million to the Company. In addition, Kaken will pay the Company an aggregate of $20.0 million towards global development costs for envu in the dermatology field through the end of 2026 and thereafter will pay a specified share of development costs applicable to the dermatology field, and for any field for which Kaken exercises its option, subject to Kaken's right to opt out of cost-sharing in certain

indications in specified circumstances. In addition, Kaken would pay the Company up to an aggregate of $36.0 million upon the achievement of regulatory milestones and upon Kaken’s exercise of its field expansion options for the rheumatology and gastrointestinal fields. In addition, the Company is entitled to receive aggregate payments of up to ¥15.5 billion upon the achievement of commercial milestones, plus tiered royalties at percentages ranging from the low double digits into the twenties on aggregate net sales of envu in Japan.

The Company evaluated the Collaboration Agreement and concluded it was within the scope of ASC 606. As of the Effective Date, the Company identified four performance obligations: (1) license to develop, manufacture and commercialize envu (the “License Obligation”), (2) development services that support the global development of envu (the “Development Services Obligation”), (3) the manufacture of the clinical supply in Japan (the “Manufacturing Services Obligation”) and (4) a material right related to the option for rheumatology disease (the “Material Right Obligation”). The License Obligation was considered functional intellectual property and distinct from other promises under the contract, as Kaken can benefit from the license on its own or together with other readily available resources. The Development Services Obligation and Manufacturing Services Obligation were considered distinct as Kaken could benefit from both of these separately with the license transferred by the Company at the inception of the agreement. The option in the rheumatology field contained a material right because its exercise does not require payment of a fee that is commensurate with the value of the additional license. No material right was assigned to the gastrointestinal field since its estimated fair value did not exceed the exercise price of the option.

The transaction price includes the upfront license fee of $20.0 million, the global development cost reimbursement of $20.0 million in the dermatology field through the end of 2026, the estimated global development cost reimbursement in the dermatology field after 2026 of $1.5 million and an immaterial amount of variable consideration related to the Manufacturing Services Obligation. The Company determined that any variable consideration related to development and regulatory milestones was deemed to be fully constrained at inception and therefore excluded from the initial transaction price due to the high degree of uncertainty and risk associated with these potential payments, and the Company could not assert that it was probable that a significant reversal in the amount of cumulative revenue recognized would not occur.

The Company developed the estimated standalone selling prices for the License Obligation and Material Right Obligation primarily based on the probability-weighted value of expected future revenues associated with each underlying license. In developing such estimates, the Company applied judgment in determining the forecasted revenue, taking into consideration the applicable market conditions, the probability of success, and the time needed to develop each indication for which the license relates. The Company developed the estimated standalone selling price for the development services and clinical supply primarily based on the resources to be committed to perform the service.

At inception of the contract, the Company allocated $17.4 million to the License Obligation, $20.8 million to the Development Services Obligation, $3.3 million to the Material Right Obligation and an immaterial amount to the Manufacturing Services Obligation. The License Obligation was satisfied in March 2025 upon transfer of the license to Kaken. For the Development Services Obligation, the Company recognizes revenue over time as Kaken consumes the benefit of such services as they are being performed. The Company measures proportional performance over time for the Development Services Obligation by using an input method based on cost incurred relative to the total estimated cost of the obligation on a quarterly basis. The Company re-evaluates the transaction price as uncertain events are resolved or other changes in circumstances occur as of the end of each reporting period.

The Company recognized revenue of $17.4 million for the year ended December 31, 2025 related to the License Obligation and $6.7 million for the year ended December 31, 2025 related to the Development Services Obligation and Manufacturing Services Obligation. As of December 31, 2025, collaboration revenue receivable was less than $0.1 million, deferred revenue, current was $1.5 million and deferred revenue, non-current was $2.6 million. The aggregate estimated amount of transaction price that was unsatisfied as of December 31, 2025 was $17.6 million, of which, $14.3 million related to the Development Services Obligation that is expected to be recognized through 2028 as the Company performs its services towards the global development of envu in the dermatology field. The remaining $3.3 million estimated amount of transaction price that was unsatisfied as of December 31, 2025 related to the Material Right Obligation and is deferred until the option is exercised or expires.

Tenet Medicines Purchase Agreement

In January 2024, ACELYRIN entered into an asset purchase agreement (“Purchase Agreement”) with Tenet Medicines, Inc. (“Tenet”). In consideration for the assets and other rights Tenet received under the Purchase Agreement, ACELYRIN is entitled to receive development, regulatory and commercial milestone payments of up to $157.5 million in the aggregate based on the achievement of specified milestones, royalties on worldwide net sales, and payments on sublicense income. On December 31, 2025, Climb Bio, Inc. (“Climb Bio”), the parent company of Tenet, filed a complaint in Delaware Superior Court seeking a declaratory judgment that budoprutug is not a “Product” under the Purchase Agreement, and therefore Climb Bio does not owe milestone or royalty payments to the Company under the Purchase Agreement. In January 2026, the Company issued a notice of material breach to Climb Bio for failing to timely pay a $3.0 million development milestone. The Company disputes Climb Bio’s interpretation and intends to seek recovery of the $3.0 million development milestone, as well as any other future milestone or royalty payments, through litigation. The matter remains pending.