Acelyrin Declines Concentra's Offer, Proceeds with Alumis Merger

In a significant development in the pharmaceutical industry, Acelyrin has rejected an unsolicited buyout offer from Concentra Biosciences, opting instead to move forward with its previously announced merger with Alumis. The decision, announced on March 4, 2025, reaffirms the commitment of both Acelyrin and Alumis to their planned combination, which is expected to create a formidable entity in the immune-mediated disease space.

Merger Details and Strategic Rationale

The Acelyrin-Alumis merger, initially revealed in early February 2025, is structured as an all-stock transaction. Upon completion, the combined company will operate under the Alumis name and be headquartered in South San Francisco. Alumis shareholders will own 55% of the new entity, with Acelyrin stockholders holding the remaining 45%.

Mina Kim, CEO of Acelyrin, emphasized the strategic value of the merger, stating, "We chose to enter into the merger agreement with Alumis after a comprehensive assessment of strategic alternatives and believe this is the best outcome for Acelyrin stockholders."

The merged company is projected to have a strong financial foundation, with an estimated $737 million in cash, cash equivalents, and marketable securities as of December 31, 2024. This substantial cash position is expected to fund operations into 2027, providing ample runway for the development of their combined pipeline.

Pipeline and Development Programs

The post-merger Alumis will boast a diverse and promising drug pipeline, leveraging assets from both companies:

1. ESK-001: Alumis' lead candidate, an allosteric tyrosine kinase 2 (TYK2) inhibitor, currently in Phase 3 trials for moderate-to-severe plaque psoriasis and lupus.

2. A-005: Another TYK2 inhibitor in early-stage development for neuroinflammatory and neurodegenerative disorders, with a Phase 2 trial in multiple sclerosis planned for later this year.

3. Lonigutamab: Acelyrin's subcutaneous monoclonal antibody targeting IGF-1R, currently in Phase 2 trials for thyroid eye disease. Recent findings have shown "clinically meaningful and competitive improvements" in various disease symptoms.

Notably, Acelyrin recently discontinued development of its former lead candidate, izokibep, an IL-17A inhibitor that had been in trials for psoriasis and other inflammatory conditions.

Concentra's Unsuccessful Bid

Concentra Biosciences, owned by Tang Capital Partners, made an unexpected offer to acquire Acelyrin in late February 2025. The proposal included $3 per outstanding share in cash, along with a contingent value right offering 80% of proceeds from potential deals involving Acelyrin's assets and intellectual properties.

After consulting with independent financial and legal advisors, Acelyrin's board of directors concluded that Concentra's offer was "not reasonably expected to result in a superior proposal to the planned merger with Alumis." This decision aligns with Concentra's mixed track record of attempting to acquire struggling biotechs, having succeeded with Jounce Therapeutics and Theseus Pharmaceuticals in 2023 but facing rejections from several other companies.

The Acelyrin-Alumis merger is expected to close in the second quarter of 2025, subject to regulatory clearances, stockholder approvals, and other customary conditions. As the pharmaceutical landscape continues to evolve, this merger represents a significant consolidation in the immune-mediated disease sector, potentially reshaping the competitive dynamics in this crucial therapeutic area.