Inhibitors of mutant BRAF (v-Raf murine sarcoma viral oncogene homolog B) represent a key example of targeted therapy used in a genetically defined patient population: Malignant melanoma carrying an activating V600BRAF mutation exhibits robust initial responses to treatment with BRAF inhibitors (BRAFis) in combination with inhibitors of the mitogen-activated protein kinase (MAPK) kinase (MEK) kinase (MEKis), with greater than 50% objective response rate (ORR) in pivotal trials (1). The gene discussed is BRAF; the disease is melanoma.