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Vimseltinib Demonstrates Promising Antitumor Activity in TGCT
In patients with tenosynovial giant cell tumor (TGCT), vimseltinib was well tolerated and demonstrated promising antitumor activity, according to data presented by Hans Gelderblom, Leids Universitair Medisch Centrum (LUMC), Leiden, Netherlands, at the 2021 Virtual ESMO Congress.
“Diffuse TGCT is a rare, locally aggressive neoplasm, where overexpression of colony-stimulating factor 1 (CSF1) drives recruitment of macrophages leading to local inflammation and joint destruction,” explained Dr Gelderblom and colleagues.
As of February 2021, 32 patients with unresectable TGCT were enrolled, and 24 patients remain. During the first phase, primary end points were safety, tolerability, and recommended phase two dose (RP2D). Antitumor activity was assessed by RECIST version 1.1.
Of 29 efficacy-evaluable patients from phase one, 13 had objective responses (1 complete, 12 partial responses; 45%). Enrollment is ongoing for phase two; 16 TGCT patients enrolled to date remain on the study.
Treatment-related adverse events (AEs) of grade 3 or higher occurred in >5% of patients and included increases in blood creatine phosphokinase, aspartate aminotransferase (AST), lipase, amylase, and hypertension. Enzyme elevations were consistent with the mechanism of action of CSF1R inhibitors.
Furthermore, treatment-related grade 3 serious AEs included metabolic encephalopathy and vaginal hemorrhage and occurred in 2 patients.
“Vimseltinib was well tolerated with encouraging and durable antitumor activity across all phase 1 TGCT dose cohorts. Safety profile of vimseltinib remains manageable with longer-term follow-up,” concluded Dr Gelderblom et al. —Alexandra Graziano
H. Gelderblom, A.R. Abdul Razak, A. Sánchez-Gastaldo. Safety and preliminary efficacy of vimseltinib in tenosynovial giant cell tumor. Presented at: the ESMO Virtual Congress 2021; September 16-21, 2020; virtual. Abstract 1821P
