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Pexidartinib Yields Tumor Regression in Patients with TGCT
According to results from a phase 1 extension study, pexidartinib demonstrated durable tumor regression, with manageable safety, in patients with tenosynovial giant cell tumor (TGCT; Clin Cancer Res. 2021 Oct 29:clincanres.2007.2021.).
William D Tap, MD, Department of Medicine, Memorial Sloan Kettering Cancer Center and Weill Cornell Medical College, and colleagues conducted this study to evaluate the response to pexidartinib among six cohorts of patients with advanced, incurable solid tumors associated with colony-stimulating factor 1 receptor (CSF1R) or KIT proto-oncogene receptor tyrosine kinase activity.
Researchers assessed the adverse events (AEs), pharmacokinetics, and tumor responses for all patients. Patients with TGCT were evaluated for tumor volume score (TVS) and patient-reported outcomes (PRO). Additionally, CSF1 transcripts and gene expression were explored in TGCT biopsies.
Of the 91 patients treated, 39 had TGCT, while 52 had other solid tumors. The median duration of treatment was 511 days in TGCT patients and 56 days in patients with other solid tumors. The response rates among TGCT patients for the full analysis set were 62% (RECIST 1.1) and 56% (TVS).
PRO assessments recorded an improvement in pain, and 76% (19/25) of TGCT tissue biopsy specimens showed evidence of abnormal CSF1 transcripts. Furthermore, researchers reported that toxicity was manageable over the entire study.
“These results offer insight into outcome patterns in cancers whose biology suggests use of a CSF1R inhibitor. Pexidartinib results in tumor regression in TGCT patients, providing prolonged control with an acceptable safety profile,” concluded Dr Tap et al.—Alexandra Graziano
