Response of BRAF inhibitor-associated squamous cell lung carcinoma to drug withdrawal.

Vemurafenib and dabrafenib, two Food and Drug Administration-approved selective BRAF kinase inhibitors (BRAFi), have revolutionized the targeted therapy of cutaneous melanoma. Off-target effects of these drugs paradoxically activate the MAP kinase pathway in BRAF wild-type cells, leading to secondary malignancies. Although cutaneous squamous cell carcinomas are by far the most frequent, emergence of potentially life-threatening secondary tumors from other sites following prolonged therapy is a growing concern.