Pimicotinib (ABSK021), a Novel Oral CSF-1R Inhibitor Developed by Abbisko Therapeutics and Partnered with Merck KGaA, Granted Priority Review in China for Tenosynovial Giant Cell Tumor

The official website of the Center for Drug Evaluation (CDE) of the China National Medical Products Administration recently announced that the Pimitespib Hydrochloride Capsules (ABSK021 capsules), submitted by Merck KGaA, are proposed to be included in the priority review, intended for use inAdult patients with tenosynovial giant cell tumor (TGCT) requiring systemic treatmentPublic information shows that Pimitinib is a novel, oral, highly selective and efficient drug developed by Abbisko.Small Molecule CSF-1R Inhibitor。Merck KGaA has global commercialization rights to the product.

Screenshot source: CDE official website

Tenosynovial Giant Cell Tumor Often Occurs in Young Adults. This rare benign tumor grows inside and around joints, primarily affecting young and middle-aged individuals of working age. Tenosynovial giant cell tumor mainly presents as joint swelling, pain, stiffness, and restricted movement, significantly impacting daily activities and limiting patients' work and social lives. Treatment generally requires surgery, but the high recurrence rate after surgery and potential complications from repeated operations pose significant challenges for patients. Therefore, there is an urgent need for systemic therapies that can control tumor growth.

Pimicotinib has been granted Breakthrough Therapy Designation by China's NMPA and the U.S. FDA, and Priority Medicines (PRIME) designation by the European Medicines Agency (EMA) for the treatment ofInoperable Tenosynovial Giant Cell Tumor (TGCT)Patients. Currently, Pimitinib is also being evaluated for the treatment of patients with chronic graft-versus-host disease. Notably, in April 2025, Abbisko announced that Merck KGaA had exercised the global commercialization option for Pimitinib under the licensing agreement signed by both parties in December 2023, with an exercise fee of $85 million. Under this collaboration, Abbisko is eligible to receive up to $605.5 million, including upfront payment, development and commercialization milestone payments, as well as double-digit percentage royalties on actual annual net sales.

In November 2024, Abbisko announced that the Phase III MANEUVER study evaluating pimitinib for the treatment of tenosynovial giant cell tumor met its primary endpoint based on the RECIST v1.1 criteria assessed by the independent blinded review committee (BIRC).At week 25, the objective response rate (ORR) achieved a statistically significant improvement, reaching 54.0%, compared to 3.2% for the placebo.MANEUVER Key Study is a three-part, randomized, double-blind, placebo-controlled Phase 3 clinical study aimed at evaluating Pimitinib forTGCT patients who meet the criteria for receiving systemic treatment and have not previously received anti-CSF1/CSF1R therapyThe efficacy and safety. The study is being conducted in China (45 patients), Europe (28 patients), the United States, and Canada (21 patients).

The study also showed that treatment with Pimitinib led to statistically significant and clinically meaningful improvements in secondary endpoints associated with important patient clinical outcomes in TGCT, includingStiffness was measured using the Numerical Rating Scale (NRS; mean change from baseline was -3.00 vs. -0.57 in the placebo group), and pain was measured using the Brief Pain Inventory (BPI; -2.32 vs. 0.23 mean change from baseline).In the MANEUVER study, Pimitinib demonstrated good tolerability, with safety data consistent with previously reported data, and no cholestatic hepatotoxicity was observed.

Abbisko previously announced the latest results of a Phase 1 open-label, multicenter study evaluating the safety and efficacy of Pimitinib in patients with TGCT. As of June 30, 2024, the updated data for the previously reported 42 patients in the 50 mg dose group is as follows:

• According to the RECIST v1.1 assessment by the Independent Review Committee (IRC), the best ORR was 85.0%. The median treatment duration was 20.67 months (0.5, 30.1), with 54.8% of patients having a treatment duration ≥18 months and 38.1% of patients having a treatment duration ≥24 months. Based on Kaplan-Meier assessment, the median duration of response has not yet been reached (NR), and 69.0% of patients remain on treatment. During long-term treatment, continuous tumor shrinkage, alleviation of pain and stiffness, and gradual improvement in joint mobility were observed.

• The overall safety profile is consistent with previous reports, and no specific adverse events were identified during long-term follow-up.

• No occurrence of cholestatic hepatotoxicity was observed.

This time, Pimi替尼 targetsTGCT Indication Proposed for Priority Review, Meaning the Product is Expected to Accelerate Patient Access.

[3] Global pivotal Phase 3 study shows Pimitinib significantly improves clinical outcomes in patients with tenosynovial giant cell tumor. Retrieved Nov 12，2024, From https://mp.weixin.qq.com/s/UqNUKrbBHH6CU8pBM8ViOg