BRAF inhibitor or BRAF/MEK inhibitor treatment for patients with metastatic BRAF V600E mutated differentiated thyroid cancer.

OBJECTIVE

The aim of this study is to demonstrate the real-life efficacy of BRAF and MEK inhibitors in patients with advanced thyroid cancer.

SUBJECTS AND

METHODS

This retrospective study evaluated the clinical efficacy of either a BRAF inhibitor (dabrafenib) alone or a BRAF inhibitor (dabrafenib) in combination with a MEK inhibitor (trametinib) in the treatment of 10 patients diagnosed with metastatic BRAF-mutant RAI refractory thyroid cancer. The primary endpoint was the investigator-assessed overall response rate (ORR).

RESULTS

The median patient age was 68 years, 60% were men, and all patients were diagnosed with progressive BRAF V600E-mutant RAI-refractory papillary thyroid carcinoma (PTC). In total, 70% of the patients had been previously treated with multikinase inhibitors. One (1%) patient received a BRAF inhibitor alone and 9 (90%) patients received a combination of BRAF and MEK inhibitors. After treatment, 2 (20%) patients achieved a complete response, 5 (50%) patients achieved a partial response, 1 (10%) patient experienced stable disease, and 1 (10%) patient experienced progressive disease. Seven (70%) patients had an objective response rate (ORR) (complete or partial response). Progression-free survival (PFS) was 70%, 40%, 30%, and 30% at 6, 12, 18, and 24 months, respectively. The 12-month overall survival (OS) rate was 90%.

CONCLUSION

Dabrafenib in combination with trametinib was well tolerated and resulted in substantial clinical benefit, with notable PFS and sustained OS, even as a second-line treatment, in patients diagnosed with metastatic, progressive BRAF V600E-mutated, RAI-refractory thyroid cancer.