U.S. Approves PIMJETMI for Tenosynovial Giant Cell Tumor, With 54% Response Rate
Key Facts
The U.S. Food and Drug Administration has approved pimicotinib, marketed as PIMJETMI, to treat adults with symptomatic tenosynovial giant cell tumor when surgery could worsen functional limitations or cause severe morbidity, according to OncLive coverage published on November 10. The decision provides a systemic treatment option for patients whose surgical risks constrain their treatment choices, within the population defined by the approval. Merck KGaA says the drug was developed by Abbisko Therapeutics and that it holds the global marketing rights. The clinical evidence cited by the company is based on the MANEUVER study, which compared the treatment with placebo in its first part. Results showed an objective response at week 25 in 54% of patients receiving pimicotinib, versus 3% in the placebo group.
The first part of MANEUVER included 94 patients, randomly assigned by the study at a 2-to-1 ratio between treatment and placebo. Participants in the pimicotinib group received a 50 mg dose once daily, while the other group received placebo, and this part of the study lasted 24 weeks. At week 25, the objective response rate assessed by an independent reviewer under RECIST v1.1 criteria was about 54% with treatment, compared with 3% with placebo. The company said the difference was statistically significant, with a probability value below 0.0001. Objective response measures tumor shrinkage or disappearance under the study criteria, while the comparison shows the size of the difference between the two groups at the specified assessment point.
In a follow-up analysis at week 97, the company said the mean change from baseline in range of motion was 19.6%. Mean change on the stiffness scale was -3.9 points, and on the pain scale it was -3.1 points, while the PROMIS-PF physical function scale recorded a change of +7.4 points. These measures place symptoms and joint function alongside tumor response, aspects relevant to patients whose surgery could lead to more severe functional limitations or severe morbidity. The company said improvements in symptoms and joint function emerged from week five and continued over two years of follow-up. Symptoms tracked in the study included pain, stiffness and range of motion.
Regarding safety during the randomized, double-blind treatment phase, treatment-emergent adverse events led one patient to discontinue treatment, equivalent to 1.6% of pimicotinib recipients. These events led to dose reductions in 7.9% of them. These two figures show discontinuations and dose reductions during that phase of the study and do not, on their own, describe the overall safety profile. The results come from a trial with a treatment group and a comparison group, before clinical measures were followed through week 97. The long-term results announced by the company addressed changes in movement, stiffness, pain and physical function.
Pimicotinib had previously received approval in China in December 2025, then in Canada in June 2026 to treat adults with symptomatic tenosynovial giant cell tumor, according to a Merck KGaA statement. The statement issued on October 26, 2026 said the U.S. application was still under review by the Food and Drug Administration at that time; the U.S. approval reported by OncLive came later. Swissmedic also granted the drug authorization in Switzerland on October 15, 2026 for the therapeutic population specified in its decision. In the stock market, Merck shares, listed under the ticker MRK, closed at $148.71 on November 9, according to EL7 data. The data provided do not include a verified figure for the share-price movement during the November 10 session or the market's reaction to the approval news.