Pexidartinib for the treatment of adult patients with symptomatic tenosynovial giant cell tumor: safety and efficacy.

INTRODUCTION: Tenosynovial giant cell tumor (TGCT) is a benign clonal neoplastic proliferation arising from the synovium often causing pain, swelling, joint stiffness, and reduced quality of life. The optimal treatment strategy in patients with diffuse-type TGCT (dt-TGCT) is evolving. Surgery is the main treatment, with a high recurrence rate and surgery-related morbidity. Radiotherapy is associated with important side effects. TGCT cells overexpress colony-stimulating factor 1 (CSF1). Pexidartinib (Turalio™) is a selective CSF1 R inhibitor, which was recently approved by the FDA for the treatment of TGCT. AREAS COVERED: This article reviews the pharmacological properties, clinical efficacy, and safety of pexidartinib. EXPERT OPINION: Pexidartinib was effective with an acceptable safety profile for advanced TGCT in phase I-III studies. The phase III trial (ENLIVEN) in unresectable TGCT met its primary endpoints of overall response rate. These results led to FDA approval for this TGCT population. Mixed or cholestatic hepatotoxicity was observed in rare cases. For this reason, pexidartinib is currently available only through a Risk Evaluation and Mitigation Strategy (REMS) Program in the USA. TGCT significantly impairs patients' quality of life. The approval of pexidartinib has changed the therapeutic armamentarium for this condition. However, strict monitoring of liver function is warranted.