Efficacy and tolerability of vemurafenib in patients with BRAF(V600E) -positive papillary thyroid cancer: M.D. Anderson Cancer Center off label experience.

CONTEXT: Vemurafenib, a selective BRAF inhibitor, appears to have promising clinical activity in patients with papillary thyroid cancer (PTC) harboring the BRAF(V600E) 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 BRAF(V600E) 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 BRAF(V600E) 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.