Abbisko Therapeutics Co., Ltd. is developing pimicotinib (previously known as ABSK-021) to treat TGCT by targeting a protein that drives the growth of the tumor, known as the colony stimulating factor 1 (CSF1). pimicotinib is an oral (50 mg) daily medication that is designed to block CSF1 at the cell source. As an investigational drug, pimicotinib has not been approved by the United States Food and Drug Administration (FDA) or any other regulatory agencies for sale or use by the public.
The purpose of their current Phase 3 study, known as MANEUVER, is to test the effectiveness and long-term safety of an investigational drug, pimicotinib, as a potential new treatment for TGCT.
As of December 2022, 49 Chinese TGCT patients have received pimicotinib at two doses (25 mg and 50 mg). Majority of side effects have been mild-to-moderate. At 6 months of treatment, TGCT patients showed improvement in range of motion, pain, and stiffness. According to their recent press release which included a more diverse patient population than their 2023 poster at the American Society of Clinical Oncology (ASCO) conference, 54% of patients with TGCT had more than 30% shrinkage following 6 months of treatment (1). Previously, the 2023 ASCO poster reported that 77.4% of patients with TGCT had more than 30% shrinkage (7% having undetectable disease from those that received 50 mg for 6 months) (2). Increasing patient diversity (e.g., 25 patients from the US were included in the recent study compared to the 2023 ASCO poster which had only Chinese patients) and more patients may play a role in these differences in effectiveness. The potential side effects listed below may change with the increase of patients enrolled to the study.
Currently, side effects include increased lab values (CK, liver enzymes like AST/ALT, LDH, and alpha-HBDH), as well as rash, facial swelling, dizziness, hypertension, itchiness, among others. Nearly 8% of patients changed dose due to side effects and 2% discontinued treatment due to side effects.
Their Phase 3 trial has closed recruitment. Patients that were enrolled in the Phase 3 study will be randomized to receive a placebo (look alike sugar pill) or pimicotinib for 6 months. Patients did not know whether they received the placebo or the drug. After 6 months, patients were allowed onto the drug regardless of whether they were on the placebo or on the study drug in the first part. Patients who received the drug during the first 6 months will be allowed to continue on the drug. The goal of this study is to determine if pimicotinib is safe and effective. The data is currently coming out in press releases but has not been published by a peer-reviewed, objective, source.
