Guo C, Chénard-Poirier M, Roda D, et al. - Researchers sought to determine the safety as well as the toxicity profile of intermittent dosing schedules of CH5126766 (a novel MEK-pan-RAF inhibitor also known as VS-6766, and previously named RO5126766), and also the antitumour activity, in patients suffering from solid tumours and multiple myeloma harbouring RAS–RAF–MEK pathway mutations. In patients with solid tumours, three intermittent oral schedules (28-day cycles) were assessed in the dose-escalation part. Antitumour activity at the recommended phase 2 dose was assessed in biomarker-selected patients in the basket dose-expansion phase. For the first time ever, antitumour activity across several cancers with RAF–RAS–MEK pathway mutations was displayed by highly intermittent schedules of a RAF–MEK inhibitor. Also, this inhibitor was shown to be tolerable. CH5126766 employed as a monotherapy and in combination regimens warrants further assessment.