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Imatinib Mesylate Demonstrates Long-Term Efficacy in TGCT
Results from a retrospective study confirm the long-term efficacy of imatinib mesylate therapy in patients with advanced tenosynovial giant cell tumors (TGCT; Sci Rep. 2019 Oct 10.)
Inhibition of CSF1/CSF-1 receptor (CSF-1R) signaling has shown efficacy in the treatment of locally advanced and recurrent diffuse TGCT. This international, multi-institutional study was conducted by Floortje G.M. Verspoor, MD, Department of Orthopedics, Radboud University Medical Center, Nijmegen, The Netherlands, and colleagues to assess the long-term efficacy of imatinib mesylate, a CSF-1R kinase inhibitor in TGCT.
Data were collected from 62 patients with locally advanced, recurrent, or metastatic TGCT from 12 institutions. Of these patients, 58 had received a single daily dose of imatinib mesylate 400 mg to 600mg. The median duration of treatment was 9 months.
The primary end points for analysis were response rate and progression-free survival (PFS). Researchers also analyzed the safety of the treatment.
A total of 17 patients achieved a complete or partial RECIST-defined response. Using a Kaplan-Meier analysis, Dr Verspoor et al found that the PFS rates were 71% and 48% at 1 and 5 years, respectively.
The majority of patients reported symptom improvement; 45 (78%) patients had lower grade adverse events (AEs), including fatigue and edema, and 5 had grade 3 to 4 toxicities.
These findings confirmed the prolonged activity of imatinib mesylate in responding cases even after discontinuation of treatment. Dr Verspoor and colleagues stated that the overall response rate (31%) was consistent with previous short-term findings, and that this study adds to the knowledge of targeting the CSF-1R pathway in patients with TGCT.
“With the advent of more potent CSF-1R inhibitors, such as emactuzumab, pexidartinib and cabiralizumab, the role of…[imatinib mesylate]…in extensive TGCT might weaken, but may be balanced by the favorable safety profile,” they concluded.—Kaitlyn Manasterski
