Merck KGaA (Merck) is filing for global regulatory approvals of its CSF-1R inhibitor pimicotinib after it met the primary and all key secondary endpoints in a Phase III trial in tenosynovial giant cell tumour (TGCT) patients.
The MANEUVER study (NCT05804045), which was run in partnership with Abbisko Therapeutics, saw an overall response rate (ORR) using tumour volume score (TVS) of 61.9% in treated patients, compared with 3.2% on placebo after 25 weeks of treatment.
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Meanwhile, Daiichi Sankyo’s Turalio (pexidartinib), which was US Food and Drug Administration (FDA) approved as a therapy for TGCT in 2019, saw an ORR by TVS of 56% in the same period. Merck’s data, however, is weaker than Ono Pharmaceutical’s Romvimza (vimseltinib), which saw a 67% ORR by TVS after 25 weeks. Ono’s therapy gained FDA approval in February 2025.
Topline data was previously announced in November 2024, in which the Blinded Independent Review Committee (BIRC) assessed that ORR as per RECIST 1.1 was 54% in pimicotinib patients compared to 3.2% of patients who received placebo. Merck also stated that one patient achieved complete response (CR) following treatment, and 33 achieved partial response (52.4%) after six months of treatment.
TGCT is a rare, non-cancerous tumour that develops in the synovium, the lining of joints, bursae, or tendon sheaths. There are approximately 43 cases per one million people, and the standard of care is surgery; however, recurrence is high, at around 40% to 60%.
Given that TGCT is not a fatal cancer, investigator Dr Vinod Ravi from the MD Anderson Cancer Center said that quality of life (QoL) improvements are incredibly important for these patients. The study therefore measured change in relative range of movement (ROM), which was a 15.54 improvement; worst stiffness saw a three-point reduction; and Brief Pain Inventory (BPI) worst pain score reduced by 2.32 compared to 0.32 in the placebo cohort.
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By GlobalDataRavi said: “This is particularly important in the usefulness of the drug in this particular patient population who are seeking therapy, not because the tumour has the potential to shorten their life, but really because they want better function, and this therapy is able to do that in a consistent manner.”
Of the patients treated with pimicotinib, 100% suffered adverse events (AEs); however, only 4.8% of these were serious AEs. Five patients had a dose reduction, and one patient discontinued treatment. There was no evidence of cholestatic hepatotoxicity or drug-induced liver injury, which Ravi believes will be a draw for patients to take pimicotinib.
Ravi added: “Some of the excitement is surrounding the response rate, which is higher than what we have encountered with previous agents, but most of the excitement is centred around the toxicity aspect that the drug has a much more favourable profile.”
The data for Merck’s TGCT drug has been released ahead of a presentation at the American Society of Clinical Oncology (ASCO) 2025 meeting, being held from 30 May to 3 June in Chicago, Illinois.
Merck acquired global rights to the drug from Abbisko Therapeutics in March 2025. The companies had previously entered an exclusive licensing agreement in December 2023, which granted Merck rights to commercialise pimicotinib for all indications in the Chinese mainland, Hong Kong, Macau and Taiwan with an exclusive option for global commercial rights of pimicotinib. The March 2025 agreement provided Merck with an exclusive license to commercialise pimicotinib worldwide.
Following the Phase III readout, Merck has filed for approval in China, with plans to initiate a filing with the FDA by the end of the year.
GlobalData predicts that Turalio will make $57m of global sales in 2030 while Romvimza is forecast to make sales of $165m in the same year. Meanwhile, sales of pimicotinib are expected to reach $76m in 2030.
GlobalData is the parent company of Pharmaceutical Technology.
