11 September 2023, Shanghai – Abbisko Therapeutics Co., Ltd. (HKEX Stock Code: 2256. HK, referred to as “Abbisko Therapeutics” hereafter) announced that the Europe EMA had approved its CSF-1R inhibitor pimicotinib（ABSK021）for a randomized, double-blind, placebo-controlled, multicenter Phase III clinical study in patients with giant cell tumor of the tendon sheath. This is another important milestone after pimicotinib was approved for Phase III clinical trial in both China and the U.S. Pimicotinib is the first small-molecule inhibitor in Abbisko’s pipeline that has been approved for Phase III clinical trial in China, the U.S., and Europe. It is the first CSF-1R inhibitor developed in China entering global Phase III clinical trial. Pimicotinib showed significant anti-tumor efficacy with a preliminary ORR of 77.4% in the clinical Phase Ib trial for the treatment of advanced tenosynovial giant cell tumor（“TGCT”）and has good safety and PK/PD characteristics.

PHASE III ABSK021-301 STUDY

The Phase III ABSK021-301 study is a randomized, double-blind, placebo-controlled, multi-centered clinical trial designed to evaluate the safety and efficacy of ABSK021 in patients with TGCT. This study consists of two parts. Part 1 is a double-blind phase, eligible patients will be randomized to ABSK021 treatment group or matching placebo group and will receive 50mg QD of ABSK021 or matching placebo (28 days/cycle) until completion of Part 1. Patients who complete Part 1 will be eligible to continue in Part 2 of the study. Part 2 is an open-label treatment phase, and all patients entering this phase will receive 50mg QD of open-label ABSK021 until 24 weeks of dosing or withdrawal from the study. Approximately 100 patients are planned to be enrolled, and the primary endpoint is 25-Week ORR by Blinded Independent Review Committee. The global multicenter Phase III study has been conducted simultaneously in the U.S. and China. Recently, patients will be enrolled simultaneously in Europe. The European part will be included in the global multi-center clinical phase III of ABSK021-301, and the results will be used for NDA applications in China, U.S., and Europe.

Pimicotinib is a novel, orally available, highly selective and potent small molecule CSF-1R inhibitor, independently developed by Abbisko Therapeutics. It has been granted the breakthrough therapy designation and Priority Medicine (PRIME) designation by China NMPA, U.S. FDA, and Europe EMA for the treatment of TGCT that is not amenable to surgery. According to epidemiological data, its incidence rate rose from 28/million people in 1998 to 49/million people in 2012, and the number of new cases in China and the U.S. is about 60,000 and 14,000 people each year. Thus, many existing patients are in desperate need of drug treatment. TCGT mainly results in swelling, pain, stiffness, and decreased activity of the affected joints which seriously affect the patient’s quality of life. There is currently no approved drug available in China, and only one systemic therapy agent has been approved in the U.S.. However, it is only available through the Risk Evaluation and Mitigation Strategy (REMS) Program due to potential liver injuries it may cause. There are unmet medical needs of TGCT patients in China, the U.S., and Europe.

Abbisko has completed a Phase Ia dose escalation study for pimicotinibin the U.S., with Phase Ib expansion ongoing in both the U.S. and China. In addition to TGCT, Abbisko is actively exploring the potential of pimicotinib in treating other indications including many types of solid tumors in clinic, and has obtained approval from NMPA to conduct a Phase II clinical study in chronic graft-versus-host disease and advanced pancreatic cancer, and also exploring its potential for treating ALS and other CNS diseases. As of the date of this press release, no highly selective CSF-1R inhibitor has been approved in China.