Alumis and Acelyrin Announce All-Stock Merger, Creating Expanded Immunology-Focused Company

Merger Details and Strategic Rationale

Immune-mediated disease specialist Alumis and eye-disease-focused Acelyrin have announced an all-stock merger, with the resulting company set to operate under the Alumis name. The merger, revealed in a postmarket release on February 6, 2025, will see Alumis stockholders owning 55% of the combined entity, while Acelyrin shareholders will hold the remaining 45%.

The newly expanded Alumis will maintain its headquarters in South San Francisco and continue under the leadership of Alumis' current executive team. Martin Babler, CEO of Alumis, emphasized that the merger would provide the company with "the financial flexibility and runway to advance an expanded late-stage pipeline, now including lonigutamab, and build commercial capabilities."

Bruce Cozadd, chair of Acelyrin's board, stated that the merger "represents the culmination of a thorough strategic review process ... to determine the best and most value-maximizing path forward." He expressed confidence in Alumis as "the right partner to optimize the development of lonigutamab and together deliver long-term stockholder value."

Financial Outlook and Pipeline Priorities

The merged company is expected to have a strong financial position, with Acelyrin contributing $448 million in cash and equivalents, while Alumis brings $289 million to the table. This combined cash reserve is projected to extend Alumis' runway into 2027, providing ample resources for advancing its expanded pipeline.

Post-merger, Alumis will prioritize key assets from both companies' portfolios. The company will continue the development of its own ESK-001, an allosteric tyrosine kinase 2 inhibitor currently in a phase 3 plaque psoriasis trial. Additionally, Alumis plans to initiate a phase 2 trial for its TYK2 inhibitor A-005 in multiple sclerosis later this year.

From Acelyrin's pipeline, the merged entity will take forward lonigutamab, an anti-IGF-1R monoclonal antibody currently in a phase 2 trial for thyroid eye disease. However, Alumis intends to "re-evaluate the development program for lonigutamab to confirm its differentiation in a capital efficient manner," suggesting a cautious approach to this asset.

Recent Challenges and Industry Context

The merger comes at a challenging time for Acelyrin, which has faced significant setbacks in recent months. In the summer of 2024, the company laid off a third of its workforce as it shifted focus from its former lead asset izokibep to lonigutamab. Acelyrin had hoped that lonigutamab could compete with Amgen's thyroid eye disease blockbuster, Tepezza.

Further complications arose when Affibody, Acelyrin's former partner, recently claimed that Acelyrin had "not been able to fully capitalize" on izokibep's potential after Acelyrin returned the rights to the drug. This series of events likely contributed to Acelyrin's decision to pursue the merger with Alumis as a strategic move to secure its future in the competitive immunology space.