Alumis is exploring strategic alternatives for its would-be rival to Amgen’s Tepezza, choosing to punt the program rather than pursue the phase 3 program envisaged before it acquired the asset.
San Francisco-based Alumis added lonigutamab, an anti-IGF-1R antibody, to its pipeline when it merged with Acelyrin last year. At the time, Alumis CEO Martin Babler called the thyroid eye disease (TED) asset a potential best-in-class drug in a market served by Amgen. But rather than start the phase 3 trial Acelyrin was planning before the merger, Alumis paused to analyze the data before deciding on the next steps.
One year after closing the merger, Alumis has decided against advancing the molecule internally. The decision could trigger a reassessment of the $51 million value assigned to lonigutamab at the time of acquisition, potentially forcing the company to write down that figure on its books.
Alumis’ external R&D expenses for lonigutamab totaled $11.9 million last year. Spending slowed in the first quarter, dragging the figure down to $232,000. While Acelyrin shareholders owned 45% of the combined company after the merger, Alumis has focused on a TYK2 inhibitor, envudeucitinib, that it was developing before the deal, racking up $224 million in external R&D costs for the asset last year.
Spending on lonigutamab marked a pullback from an asset that Acelyrin went all in on shortly before the merger. In 2024, Acelyrin stopped new internal investment in autoimmune prospect izokibep to focus on lonigutamab, reflecting a belief that the subcutaneous drug could provide more durable responses than intravenous Tepezza with fewer side effects, beating Amgen on convenience and the risk-benefit profile.
Competition for the TED market has intensified since Acelyrin committed to lonigutamab. A phase 3 trial found that subcutaneous delivery of Tepezza using an on-body injector is as effective as the existing intravenous product, positioning Amgen to counter the potential for rivals to compete on convenience. Viridian Therapeutics has reported two phase 3 wins for its subcutaneous challenger without wowing investors.
Finding a partner for lonigutamab would extend the series of deals involving the asset. ValenzaBio picked up rights to the asset outside of oncology from Pierre Fabre in 2021. Acelyrin bought ValenzaBio in 2023 and merged with Alumis in 2025. Had Alumis advanced lonigutamab, it could have paid up to $100.5 million in development and regulatory milestones and up to $390 million tied to commercial successes.