Progression of KRAS mutant pancreatic adenocarcinoma during vemurafenib treatment in a patient with metastatic melanoma

Vemurafenib is a tyrosine kinase inhibitor of BRAF that prolongs survival in patients with BRAF V600-mutant metastatic melanoma. Secondary cutaneous malignancies are a well-documented toxicity of vemurafenib, thought to be mediated by enhanced ERK signalling in BRAF wild-type, RAS-mutant cells. Vemurafenib could also promote growth of non-cutaneous secondary malignancies by a similar mechanism. We present a case of an individual who received vemurafenib for metastatic melanoma and experienced rapid growth of a pre-existing KRAS-mutant pancreatic adenocarcinoma.