Merck KGaA received FDA approval for 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 whom surgical resection may cause worsening functional limitation or severe morbidity.

The approval gives patients who are not good candidates for surgery a new oral option for a disease that has historically been managed primarily through operative intervention.

Danny Bar-Zohar, chief executive officer healthcare and member of the executive board of Merck KGaA, Darmstadt, Germany, frames the approval as both a patient-focused and strategic milestone. “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,” Bar-Zohar says. “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.”

What is TGCT and why has it been hard to treat?

TGCT is a rare, locally aggressive tumor that occurs in or around the joints, leading to progressive worsening of symptoms including pain and reduced mobility of the affected joint and significantly impacting physical function in what is typically an otherwise healthy and young patient population.¹ Up to half of people with TGCT can be initially misdiagnosed, which results in delays in appropriate disease management. If left untreated, or in recurrent cases, TGCT may cause cumulative morbidity and irreversible damage to the bone, joint, and surrounding tissues.¹

What did the Maneuver trial show?

FDA’s approval is based on primary and longer-term results from the global Phase III Maneuver study. Pimjetmi demonstrated a statistically significant improvement in objective response rate at week 25, as assessed by blinded independent review committee based on RECIST v1.1, compared with placebo, 56% versus 3% for placebo.² Pimjetmi also demonstrated clinically meaningful and statistically significant improvements compared with placebo across secondary endpoints relevant to patients’ daily lives, improving relative range of motion, physical functioning, and pain.² The effect of pimicotinib had an early onset, with 41.3% of patients (26 of 63) experiencing an objective response to therapy after 13 weeks.

Vinod Ravi, MD, MS, MBA, department of sarcoma medical oncology, division of cancer medicine, UT MD Anderson, and an investigator on the Maneuver trial, says the data support pimicotinib as a meaningful once-daily option. “The results of the Phase III Maneuver trial demonstrate that Pimjetmi elicits durable tumor response with a manageable tolerability profile,” Ravi says. “This combination of efficacy and safety data will potentially address the needs of people living with TGCT in a once-daily treatment option.”

In the trial, pimicotinib was well-tolerated, with no evidence of cholestatic hepatotoxicity or hair/skin hypopigmentation.² During the randomized, double-blind treatment phase of the trial, treatment-emergent adverse events leading to treatment discontinuation occurred in one patient (1.6%) treated with pimicotinib, and treatment-emergent adverse events leading to dose reduction occurred in 7.9% (n=5) of pimicotinib-treated patients.²

Sydney Stern, PhD, MS, TGCT Support, a program of the Life Raft Group, points to the day-to-day burden the disease places on patients. “TGCT can profoundly affect patients’ daily lives through persistent pain, swelling, and loss of joint function,” Stern says. “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.”

That kind of patient input increasingly shapes how companies prioritize rare tumor programs industry-wide. Pedro Valencia, VP of asset strategy leadership in oncology at AbbVie, told Pharmaceutical Executive last year that partnering with advocacy groups on unmet needs in rare tumor populations helps ensure “these insights shape our development plans to ensure no patient is left behind.”

Sources

1. FDA Approves Pimjetmi (pimicotinib) for Patients with Tenosynovial Giant Cell Tumor Merck KGaA November 10, 2026, https://www.emdgroup.com/en/news/pimicotinib-fda-approval-11-10-2026.html
2. MANEUVER: A Phase III study of pimicotinib to assess efficacy and safety in tenosynovial giant cell tumor patients National Library of Medicine September 17, 2024, https://pubmed.ncbi.nlm.nih.gov/39287124/