BRAF-mutated metastatic melanoma patients with second mutation do not show increased drug resistance

Scientists at the University of California, Los Angeles have discovered that a second mutation found in the tumors of patients with BRAF-mutated metastatic melanoma does not contribute to resistance to BRAF inhibitor drugs. "As BRAF inhibitors gain widespread use for advanced melanoma treatment, biomarkers for drug sensitivity or resistance are urgently needed," the study states. "We identify here concurrent activating mutations in BRAF and MEK1 in melanomas and show that the presence of a downstream mutation in MEK1 does not necessarily make BRAF mutant melanomas resistant to BRAF inhibitors." About half of patients with metastatic melanoma have the BRAF mutation and can be treated with the inhibitor pill Zelboraf. The research team analyzed tumor samples from 31 melanoma patients treated with a BRAF inhibitor. Sixteen percent of the samples carried the double mutations before the cancer was treated.