Abbisko Therapeutics Completes the First Patient Dose in Global Phase III Trial of CSF-1R Inhibitor – Pimicotinib（ABSK021）

27 April, 2023, Shanghai – Abbisko Therapeutics Co., Ltd. (“Abbisko Therapeutics”hereafter) today announced first patient dosing of “A Phase 3, Randomized, Double-blind, Placebo-Controlled, Multicenter Study of ABSK021 to Assess the Efficacy and Safety in Patients with Tenosynovial Giant Cell Tumor” in Beijing Jishuitan Hospital.

Pimicotinib is a novel, orally available, highly selective, and highly potent small molecule inhibitor of CSF-1R independently discovered and developed by Abbisko Therapeutics. A number of studies have shown that blocking the CSF-1R signaling pathway could effectively modulate and change macrophage functions, and potentially treat many macrophage-dependent human diseases. Pimicotinib (ABSK021) has been granted the breakthrough therapy designation from both CDE on 20 Jul 2022 and FDA on 30 Jan 2023 for the treatment of tenosynovial giant cell tumor (TGCT) patients who are not amenable to surgery.

TGCT, is a locally aggressive neoplasm which affects synovial joints, mucous sacs, and tendon membranes, resulting in swelling, pain, stiffness, and decreased activity of the affected joints which seriously affect the patient's quality of life. Currently there is no approved drug available in China, and there’s only one systemic therapy agent approved in the US. However, due to the potential liver injury it may cause, it is available only through the Risk Evaluation and Mitigation Strategy (REMS) Program. There are unmet medical needs of TGCT patients in both China and the US.

Pimicotinib is the first highly selective CSF-1R inhibitor discovered by a Chinese company that entered into a global phase III clinical trial. The study is also the first global Phase III study of TGCT to be conducted simultaneously in China and the US. Approximately 100 participants are scheduled to be enrolled in approximately 50 centers worldwide, including 30 centers in China.

PHASE 3 ABSK021-301 STUDY

The Phase 3 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 tenosynovial giant cell tumors. 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.