Pimicotinib Shows Promise in Phase 2 Trial for Chronic Graft-versus-Host Disease

• Preliminary Phase 2 results show pimicotinib achieved a 64% overall response rate (ORR) in chronic Graft-versus-Host Disease (cGvHD) patients who had progressed or not responded to prior therapies.
• The study demonstrated responses in various organs affected by cGvHD, including the gastrointestinal tract, oral cavity, eyes, liver, joints, fascia, esophagus, skin, and lungs.
• Pimicotinib also showed efficacy in treating cGvHD-associated Bronchiolitis Obliterans Syndrome (BOS), with some patients experiencing improved lung function and reduced shortness of breath.
• The majority of adverse events were Grade 1 and reversible, suggesting pimicotinib is well-tolerated in heavily pre-treated patients with cGvHD.

Abbisko Therapeutics announced preliminary Phase 2 study results for pimicotinib (ABSK021) in patients with chronic Graft-versus-Host Disease (cGvHD) who have either progressed or not responded to one or more prior lines of therapy. The data, presented at the 66th ASH Annual Conference, demonstrated a 64% overall response rate (ORR) in a subset of patients receiving 20mg QD of pimicotinib.

Clinical Efficacy

As of November 22, 2024, the preliminary data indicated a 64% ORR among patients receiving pimicotinib 20mg QD. Responses were observed across all affected organs, including the gastrointestinal tract, oral cavity, eyes, liver, joints and fascia, esophagus, skin, and lungs. This suggests a broad therapeutic effect of pimicotinib in managing the diverse manifestations of cGvHD.

Impact on cGvHD-associated BOS

Pulmonary manifestations, such as shortness of breath and diminished lung function leading to Bronchiolitis Obliterans Syndrome (BOS), pose a significant challenge in cGvHD treatment. The study highlighted lung response results in six subjects: one subject achieved an 11% increase in FEV1 (forced expiratory volume in the first second), one subject's FEV1 recovered to more than 75% after treatment, returning to normal levels, and the remaining four subjects saw improvements in the NIH Lung score with significant improvements in shortness of breath. These findings suggest pimicotinib's potential in treating cGvHD-associated BOS.

Safety and Tolerability

The results indicated that pimicotinib was well-tolerated in heavily pre-treated patients with cGvHD. The majority of adverse events were Grade 1 and reversible. Rapid and durable responses were observed across both inflammation-dominated and fibrosis-dominated organs, accompanied by patient-reported reductions in organ-specific symptom burden.

Pimicotinib (ABSK021)

Pimicotinib (ABSK021) is a novel, orally administered, highly selective, and potent small-molecule inhibitor of CSF-1R being independently developed by Abbisko Therapeutics. It has been granted breakthrough therapy designations (BTD) by China National Medical Products Administration (NMPA) and the U.S. Food and Drug Administration (FDA), as well as priority medicine (PRIME) designation from the European Medicines Agency (EMA) for the treatment of patients with TGCT that are not amenable to surgery. Pimicotinib is also currently being evaluated for the treatment of patients with chronic Graft-versus-Host Disease.