FDA Approves PIMJETMI ® (pimicotinib) for Patients with Tenosynovial Giant Cell Tumor

Merck, a leading science and technology company, announced today that the U.S. Food and Drug Administration (FDA) has approved PIMJETMI^® (pimicotinib), a once-daily oral colony stimulating factor-1 receptor (CSF-1R) inhibitor, as a systemic treatment for adults with symptomatic tenosynovial giant cell tumor (TGCT) for which surgical resection may cause worsening functional limitation or severe morbidity.

“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 for the Healthcare business of Merck. “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.”

TGCT is a rare, locally aggressive tumor occurring in or around the joints leading to progressive worsening of symptoms including pain and reduced mobility of the affected joint, significantly impacting physical function in what is typically an otherwise healthy and young population. It has been reported that up to half of people with TGCT can be initially misdiagnosed, resulting in delays in the appropriate disease management.³ If left untreated or in recurrent cases, TGCT may result in cumulative morbidity and irreversible damage to the bone, joint and surrounding tissues.

“The results of the Phase 3 MANEUVER trial demonstrate that PIMJETMI elicits durable² 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.”

FDA approval is based on primary and longer-term results from the global Phase 3 MANEUVER study. PIMJETMI demonstrated a statistically significant improvement in objective response rate (ORR) at week 25 as assessed by blinded independent review committee (BIRC) based on RECIST v1.1 compared with placebo (56% vs. 3% for placebo; p<0.0001). PIMJETMI also demonstrated clinically meaningful and statistically significant improvements as compared to placebo across secondary endpoints relevant to patients’ daily lives, improving relative range of motion (p=0.0003), physical functioning (p=0.0074), and pain (p<0.0001). The MANEUVER study was presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting. In the longer-term follow up (median 14.3 months for patients initially randomized to pimicotinib) presented at the European Society for Medical Oncology (ESMO) Congress in 2025, the median duration of response was not reached. The majority (77%) of patients with response at 25 weeks maintained clinical benefit after an additional 12 months of follow up, demonstrating the durability² of response with PIMJETMI.

In MANEUVER, pimicotinib was well-tolerated, with no evidence of cholestatic hepatotoxicity or hair/skin hypopigmentation. During the randomized, double-blind treatment phase of the trial, treatment-emergent adverse events (TEAEs) leading to treatment discontinuation occurred in one patient (1.6%) treated with pimicotinib; TEAEs leading to dose reduction occurred in 7.9% (n=5) of pimicotinib-treated patients.

“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 FDA approval of PIMJETMI builds on growing momentum for the Merck rare tumors portfolio that included two other drug approvals in the past three years including OGSIVEO^®, the first FDA-approved treatment for adults with progressing desmoid tumors who require systemic therapy. The PIMJETMI approval follows its approval in China by the National Medical Products Administration (NMPA) in December 2025, in Canada by Health Canada in June 2026 for the treatment of adult patients with symptomatic TGCT, as well as in Switzerland by its own independent national regulatory authority, the Swissmedic in October 2026.

The application for PIMJETMI was reviewed under Project Orbis, an international initiative of the FDA Oncology Center of Excellence. Application reviews are ongoing for partners of Project Orbis, an international framework for collaboration.

¹In the global Phase 3 MANEUVER clinical trial, the effect of pimicotinib had an early onset, with 41.3% (26 of 63) of patients experiencing objective response to therapy after 13 weeks.
² The majority (77%) of patients with response at 25 weeks maintained this clinical benefit after an additional 12 months of treatment.
³ Stern S, et al. Localized and diffuse tenosynovial giant cell tumor: real-world results from a patient observational registry. Future Oncol. 2025;21(12):1501-1510.

About MANEUVER
The pivotal, global, Phase 3 MANEUVER study is a three-part, randomized, double-blind, placebo-controlled study to assess the efficacy and safety of PIMJETMI in patients with TGCT who were eligible for systemic therapy and have not received prior anti-CSF-1/CSF-1R therapy.

The ongoing study is being conducted by Abbisko Therapeutics and enrolled patients globally in USA, Canada and Europe (n=49) and China (n=45).

In the double-blind Part 1, 94 patients were randomized 2:1 to receive either 50 mg QD of PIMJETMI (n=63) or placebo (n=31) for 24 weeks. In addition to the primary endpoint of ORR at week 25, as measured by RECIST v1.1 by BICR, secondary endpoints include tumor volume score (TVS), relative range of motion, pain by Brief Pain Inventory (BPI), and physical function measured by Patient-Reported Outcomes Measurement Information System (PROMIS-PF).

After the double-blind Part 1, all eligible patients from either arm could continue to the open-label Part 2 and receive up to 24 weeks of pimicotinib treatment. Patients who completed Part 2 could then enter the open-label extension phase (Part 3) for extended treatment and safety follow-up.

About PIMJETMI^® (pimicotinib)
PIMJETMI, developed by Abbisko Therapeutics, is a novel, orally administered, highly selective and potent small-molecule inhibitor of CSF-1R. PIMJETMI has been approved for the treatment of adult patients with symptomatic TGCT for which surgical resection will potentially cause functional limitation or relatively severe morbidity by China National Medical Products Administration (NMPA) and Health Canada. PIMJETMI has received priority medicine (PRIME) designation from the European Medicines Agency (EMA). Merck holds worldwide commercialization rights for PIMJETMI.

About Merck
Merck, a leading science and technology company, operates across life science, healthcare and electronics. More than 62,000 employees work to make a positive difference to millions of people’s lives every day by creating more joyful and sustainable ways to live. From providing products and services that accelerate drug development and manufacturing as well as discovering unique ways to treat the most challenging diseases to enabling the intelligence of devices – the company is everywhere. In 2025, Merck generated sales of € 21.1 billion in 65 countries.

Scientific exploration and responsible entrepreneurship have been key to Merck’s technological and scientific advances. This is how Merck has thrived since its founding in 1668. The founding family remains the majority owner of the publicly listed company. Merck holds the global rights to the Merck name and brand. The only exceptions are the United States and Canada, where the business sectors of Merck operate as MilliporeSigma in life science, EMD Serono in healthcare, and EMD Electronics in electronics.

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