In This Article:
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.
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.
Ravi 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.