BOSTON–EMD Serono, the U.S. and Canadian healthcare business of Merck KGaA, Darmstadt, Germany, has received approval from the U.S. Food and Drug Administration (FDA) for PIMJETMI (pimicotinib), a once-daily oral treatment for adults with symptomatic tenosynovial giant cell tumor (TGCT) who face significant risks from surgical removal of their tumors.
The approval provides a new systemic treatment option for patients with TGCT, a rare, locally aggressive tumor that develops in or around joints and can cause persistent pain, swelling, reduced mobility, and progressive damage to surrounding tissues.
PIMJETMI is a colony stimulating factor-1 receptor (CSF-1R) inhibitor designed for patients whose tumors cannot be surgically removed without potentially worsening physical limitations or causing severe complications.
“People living with TGCT have long faced difficult treatment decisions as they navigate a disease that can significantly affect their daily lives including their mobility,” said Danny Bar-Zohar, CEO Healthcare and Member of the Executive Board of Merck KGaA, Darmstadt, Germany. “Translating scientific innovation into clinically meaningful advances for people living with rare tumors is a strategic imperative for our company, as we continue our commitment to addressing significant unmet needs. With the approval of PIMJETMI in the U.S., we strengthen our leadership position and growing portfolio in rare tumors and bring real hope to patients and their families.”
The FDA based its decision on results from the global Phase 3 MANEUVER clinical trial, which demonstrated significant improvements in tumor response, physical function, joint mobility, and pain compared with placebo.
At week 25, PIMJETMI achieved an objective response rate of 56%, compared with 3% among patients receiving placebo. The difference was statistically significant, with a p-value of less than 0.0001.
The trial also showed statistically significant improvements in range of motion, physical functioning, and pain, suggesting that treatment benefits extended beyond tumor reduction to patients’ everyday activities.
Longer-term findings presented at the 2025 European Society for Medical Oncology Congress indicated sustained responses. After a median follow-up of 14.3 months among patients initially assigned to pimicotinib, the median duration of response had not been reached.
Approximately 77% of patients who responded to treatment at 25 weeks maintained clinical benefits after an additional 12 months of follow-up.
“The results of the Phase 3 MANEUVER trial demonstrate that PIMJETMI elicits durable tumor response with a manageable tolerability profile,” said Vinod Ravi, MD, MS, MBA, Department of Sarcoma Medical Oncology, Division of Cancer Medicine, UT MD Anderson, an investigator on the MANEUVER trial. “This combination of efficacy and safety data will potentially address the needs of people living with TGCT in a once-daily treatment option.”
Safety findings from the trial showed no evidence of cholestatic hepatotoxicity or hair and skin hypopigmentation. During the randomized, double-blind treatment period, one patient receiving pimicotinib, representing 1.6% of the treatment group, discontinued therapy because of treatment-emergent adverse events.
Five patients, or 7.9% of those receiving pimicotinib, required dose reductions because of adverse events.
TGCT primarily affects joints and surrounding tissues, often in younger adults who are otherwise healthy. The disease can substantially interfere with daily activities, particularly when tumors recur or are difficult to remove surgically.
According to the company, studies have indicated that as many as half of patients with TGCT may initially receive an incorrect diagnosis, potentially delaying appropriate treatment. Without effective management, the condition can cause lasting damage to bones, joints, and nearby tissues.
“TGCT can profoundly affect patients’ daily lives through persistent pain, swelling, and loss of joint function,” said Sydney Stern, PhD, MS, TGCT Support, a Program of the Life Raft Group. “For symptomatic patients who are not likely to benefit from surgery alone, there remains need for treatment options which are tolerable and effectively address the burden of disease, shrink their TGCT, and improve pain and function.”
The U.S. approval expands Merck KGaA’s portfolio of treatments for rare tumors, which includes OGSIVEO, an FDA-approved therapy for adults with progressing desmoid tumors who require systemic treatment.
PIMJETMI previously received regulatory approval in China in December 2025, Canada in June 2026, and Switzerland in October 2026.
The FDA reviewed the application through Project Orbis, an initiative of its Oncology Center of Excellence that facilitates international collaboration on cancer drug reviews. Regulatory reviews involving other participating authorities remain underway.
EMD Serono has also expanded its patient support initiatives for TGCT. In May 2025, Merck KGaA launched TGCT & Me, a free U.S. mobile application developed with input from patients, healthcare professionals, and a patient advocacy organization to help individuals manage the challenges associated with the disease.
