Alys Pharmaceuticals Doses First Subject in Phase 1/1b Trial of ALY-301, a Mast Cell–Selective c-Kit Inhibitor for Cold Urticaria

Alys Pharmaceuticals, Inc., an immune-dermatology company, announced that the first subject has been dosed in a Phase 1/1b clinical study of ALY-301, a first-in-class mast cell–selective c-Kit inhibitor being developed for the treatment of Cold Urticaria, a subtype of Chronic Inducible Urticaria (CIndU). Initial data readouts are expected in 2026.

Precision Approach to Mast Cell Depletion

ALY-301 is a cis-targeting bispecific antibody that binds both c-Kit and CD203c to selectively deplete mast cells while sparing other c-Kit–expressing cells such as melanocytes and hematopoietic stem cells. This selectivity is designed to enable chronic dosing in mast cell–driven diseases and to avoid the safety limitations associated with conventional c-Kit inhibitors.

“Chronic urticaria is a condition where the patient burden is often underestimated,” said Professor Martin Metz, Principal Investigator for the study and Professor of Dermatology at the Charité – Universitätsmedizin Berlin. “ALY-301’s mast cell selectivity, combined with its efficacy potential, makes it one of the most promising approaches I’ve encountered in the immune-dermatology space.”

Phase 1/1b Study Design

The ongoing multicenter, randomized, double-blind, placebo-controlled Phase 1/1b trial (NCT07181369) is evaluating the safety, tolerability, pharmacology, and preliminary efficacy of ALY-301. The study includes healthy volunteers and patients with Cold Urticaria who remain symptomatic despite antihistamine treatment.

The first patient was dosed at Charité – Universitätsmedizin Berlin, with expansion to additional sites in Germany planned in the coming months. The trial was cleared following a Clinical Trial Application (CTA) submission in June 2025.

Focus on Chronic Urticaria and Broader Indications

Chronic Urticaria encompasses a group of mast cell–driven skin disorders characterized by recurrent itchy wheals or hives that can last months or years, significantly affecting quality of life. Despite existing therapies, unmet medical need remains high, and the global urticaria market is projected to reach several billion dollars over the next decade.

“Dosing the first subject marks a major milestone for Alys and for our Granular platform,” said Thibaud Portal, Co-founder and Chief Operating Officer, Alys Pharmaceuticals. “ALY-301 represents the first mast cell–selective c-Kit inhibitor to enter clinical testing and advances our goal of developing targeted therapies for patients with limited options.”

Professor Lars French, Chief Medical Officer of Alys, added, “This trial allows us to evaluate, for the first time in patients, the effects of a bispecific antibody that inhibits mast cell c-Kit while sparing other cell types. Its selectivity may support safer long-term management of Chronic Urticaria.”

Expanding Immuno-Dermatology Pipeline

The ALY-301 study is Alys’s second clinical program in 2025 and the first from its Granular platform, which focuses on mastocyte-selective therapies. The company’s broader pipeline targets atopic dermatitis, chronic spontaneous urticaria, vitiligo, systemic mastocytosis, and related immune-dermatologic disorders. Multiple proof-of-concept readouts are anticipated by 2027.

About Alys Pharmaceuticals

Alys Pharmaceuticals, Inc. is a Boston- and Lausanne-based immuno-dermatology company backed by Medicxi with $100 million in financing. The company’s leadership includes experts across dermatology and molecular biology, including co-founders John Harris, Brian Kim, Lars French, Craig Mello, and Mark Prausnitz. Alys entered the clinic in early 2025 with a siRNA platform from its affiliate Aldena Therapeutics, and is now advancing mastocyte-selective biologics through its Granular Therapeutics subsidiary.

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