Pimicotinib (previously known as ABSK-021) is being developed to treat TGCT by targeting a protein that drives the growth of the tumor, known as the colony stimulating factor 1 (CSF1). It is being developed by Merck KgaA and EMD Serono for the treatment of TGCT. 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 other regulatory agencies for sale or use by the public in Europe, Canada, Australia, or elsewhere. However, on December 21, 2025, pimicotinib was approved for symptomatic adult patients with TGCT in China. It is expected that pimicotinib will rollout in other countries upon approvals.
The pivotal Phase 3 study, known as MANEUVER, tested the effectiveness and long-term safety of an investigational drug, pimicotinib, as a potential new treatment for TGCT. This pivotal study was randomized where patients received pimicotinib or a placebo (look alike sugar pill) for 6 months. After 6 months, patients on placebo were given the chance to "crossover" and receive pimicotinib and patients receiving pimicotinib were allowed to continue receiving it.
As of 2025, 90 TGCT patients (45 in China, 28 in Europe, and 21 in North America) received 50 mg of pimicotinib once everyday. All patients had symptomatic TGCT and were at least 18 years of age. Unlike other trials in TGCT, MANEUVER enrolled patients with both diffuse and localized TGCT. Most of patients had prior surgeries, but not all. Fifty-four percent of patients had significant tumor shrinkage, measured as those who have 30% or more shrinkage in their TGCT, after 6 months of treatment with pimicotinib(1). The tumor shrinkage increased with longer treatment out to 12 months (76% of patients had 30% or more TGCT shrinkage following 12 months of treatment). Patients that received pimicotinib also had significant reductions in stiffness, pain, and improved range of motion following 6-months of treatment.
Majority of side effects have been mild-to-moderate. According to their presentations at American Society of Clinical Oncology (ASCO) conference and European Society of Medical Oncology (ESMO) conference, all patients had some side effect. The most common side effects include itching, facial swelling, rash, swelling around the eyes, fatigue, nausea, and headaches which were reported in more than 20% of all patients receiving pimicotinib. Additional lab abnormalities were seen such as CK, liver enzymes like AST/ALT, LDH, and alpha-HBDH, although patients were not symptomatic due to labs. Nearly 8% of patients changed dose due to side effects and 2% discontinued treatment due to side effects.
