One patient on a schedule of vemurafenib @ mg twice a day and cobimetinib @ mg once a day @/@ had grade @ fatigue for more than @ days ; one patient on a schedule of vemurafenib @ mg twice a day and cobimetinib @ mg once a day @/@ had a grade @ prolongation of QTc ; and two patients on a schedule of vemurafenib @ mg twice a day and cobimetinib @ mg @/@ had dose-limiting toxic effects-one developed grade @ stomatitis and fatigue and one developed arthralgia and myalgia .