BOSTON — Pimicotinib, an investigational therapy for tenosynovial giant cell tumor (TGCT), has shown significant efficacy and strong patient-reported benefits in a global Phase 3 clinical trial, according to results presented by EMD Serono at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting.
The Phase 3 MANEUVER study, conducted across China, Europe, and North America, found that once-daily pimicotinib produced a 54.0% objective response rate (ORR) at week 25, compared to just 3.2% in the placebo group (p<0.0001). Nearly all patients treated with pimicotinib saw a reduction in tumor size, with some achieving complete or partial responses.
Pimicotinib, developed by Abbisko Therapeutics and studied in partnership with EMD Serono, is a colony stimulating factor-1 receptor (CSF-1R) inhibitor targeting TGCT, a rare and often debilitating disease that causes joint pain, swelling, and impaired mobility. The condition mainly affects working-age adults.
In addition to meeting its primary endpoint, the MANEUVER study met all five key secondary endpoints, demonstrating statistically significant and clinically meaningful improvements in pain, stiffness, range of motion, physical function, and tumor volume reduction. After just 13 weeks of treatment, over 41% of patients in the pimicotinib group had already responded to therapy.
“These results mark the highest objective response rate we’ve seen to date for a systemic TGCT treatment,” said Prof. Niu Xiaohui of Beijing Jishuitan Hospital. “Beyond tumor shrinkage, the improvements in stiffness, pain, and mobility are especially important for patients trying to live normal, active lives.”
According to study data, 61.9% of pimicotinib-treated patients experienced a tumor volume reduction of at least 50%, a notable difference from the 3.2% in the placebo group (p<0.0001). Importantly, patient-reported improvements were observed regardless of whether the tumor met formal response criteria.
Pimicotinib also demonstrated a favorable safety profile, with few patients discontinuing treatment due to side effects. Only one patient (1.6%) stopped treatment due to adverse events, and dose reductions were needed in just 7.9% of cases. No significant issues related to liver toxicity or pigment changes were observed.
Danny Bar-Zohar, CEO of Healthcare at Merck KGaA and Global Head of R&D, emphasized the impact of the findings: “TGCT may be rare, but it can severely limit quality of life. The MANEUVER trial sets a new benchmark for treating this disease, and we plan to begin regulatory submissions later this year.”
The findings position pimicotinib as a potential best-in-class therapy for TGCT, offering new hope for patients who currently have limited treatment options.
