US-based biopharmaceutical companies Alumis and Acelyrin have made changes to their previously announced merger agreement, increasing the share exchange ratio to 0.4814:1.
The deal was first announced in February 2025. As per the original terms, Acelyrin’s stockholders were to be issued 0.4274 shares of Alumis common stock for each Acelyrin share owned.
The merger’s primary objective is to establish a major late-stage clinical biopharmaceutical company focusing on developing and commercialising transformative therapies for immune-mediated diseases.
Following the merger, the combined entity will retain the Alumis name, with headquarters based in South San Francisco.
The updated share exchange ratio shifts the ownership distribution in the merged entity, with Alumis shareholders holding about 52% and Acelyrin shareholders owning approximately 48% on a fully diluted basis.
The revision aims to align with current market conditions and provides enhanced value creation opportunities for shareholders.
Alumis president, CEO, and chairman Martin Babler said: “In recognition of the current market conditions and evolving investor expectations for a successful combination, we have revised the terms of our agreement with Acelyrin, enabling enhanced value creation opportunities for our respective stockholders.
“This was carefully considered by our board of directors and we continue to firmly believe in the merits of the transaction.”
Alumis is currently advancing ESK-001, an oral TYK2 inhibitor undergoing a Phase 3 trial for plaque psoriasis and a Phase 2b trial for systemic lupus erythematosus. Clinical data from the Phase 2 psoriasis trial is anticipated in 2025.
Additionally, Alumis is working on A-005, a CNS-penetrant TYK2 inhibitor targeting multiple sclerosis and Parkinson’s disease, with Phase 2 trials slated for commencement in 2025 for multiple sclerosis.
On the other hand, Acelyrin is progressing with lonigutamab, aimed at treating thyroid eye disease and currently in Phase 2 trials.
Post-merger, the development of lonigutamab will continue under Alumis, leveraging the combined resources and expertise to optimise its progress within the expanded portfolio.
Acelyrin board of directors chair and board transaction committee member Bruce Cozadd said: “Since announcing the merger, we have had extensive conversations with our stockholders who have expressed an understanding of the strategic rationale for this transaction, while also sharing their perspectives on the value provided to Acelyrin stockholders.
“This amended agreement reflects this dialogue with stockholders and meaningfully builds upon the previously announced agreement, which was the result of a rigorous, objective, and competitive process facilitated by the Acelyrin board.”
Both companies expect to finalise the merger in Q2 2025, contingent on shareholder approval and meeting customary conditions.
