Efficacy and Tolerability of Vemurafenib in Patients with BRAFV600E -Positive Papillary Thyroid Cancer: M.D. Anderson Cancer Center Off Label Experience

Abstract

Abstract Context: Vemurafenib, a selective BRAF inhibitor, appears to have promising clinical activity in patients with papillary thyroid cancer (PTC) harboring the BRAFV600E mutation. Objective: To determine the efficacy and safety of vemurafenib when used outside of a clinical trial. Design: A retrospective review at MD Anderson Cancer Center. Methods: The best responses were evaluated using RECIST v1.1. A single radiologist reviewed all images. Adverse events (AEs) were evaluated using CTCAE v.4.0. Results: We identified 17 patients with advanced PTC harboring the BRAFV600E mutation who were treated with vemurafenib outside of a clinical trial. Median age at diagnosis was 63 years, and 53% were male. At vemurafenib start, 3 (18%) patients had disease confined to the neck, and 14 (72%) had distant metastases. Tyrosine kinase inhibitors had been previously administered to 4 (24%) patients. Two (12%) patients discontinued vemurafenib because of AEs before restaging. Best response: partial response (PR) in 7/15 (47%) and stable disease (SD) in 8/15(53%) patients. The rate of durable response (PR plus SD ≥ 6 months) was 67%. Median time to treatment failure was 13 months. There was no association between change in thyroglobulin and tumor size. Drug discontinuation, drug interruptions, and dose reductions were needed in 5 (29%), 13 (76%), and 10 (59%) patients, respectively. Most common AEs were fatigue (71%), weight loss (71%), anorexia (65%), arthralgias (59%), hair loss (59%), rash (59%), hand-foot syndrome (53%), calluses (47%), diarrhea (47%), fever (41%), dry mouth (35%), nausea (35%), and verrucous keratosis (35%). Grade ≥ 3 AEs were present in 8 (47%) patients. Conclusions: Vemurafenib is a potentially effective and well-tolerated treatment strategy in patients with advanced PTC harboring the BRAFV600E mutation. Our results are similar to those reported in a phase II clinical trial and support the potential role of vemurafenib in this patient population.