KRAS and colorectal carcinoma: Third, MEK inhibitor monotherapy is more effective in clinical trials of NRAS-mutant melanoma than in KRAS-mutant CRC, as early phase III trial data of MEK162 (binimetinib) in NRAS-mutant melanoma showed the study met its primary endpoint of improvement in progression-free survival (unpublished data), while MEK inhibitors had no evidence of efficacy in phase I studies in RAS-mutant CRCs [58].