This is an open-label, multi-center Phase I/IIa two-part study with a sequential dose escalation part, followed by three parallel Extension cohorts (BRAF-mutated melanoma, BRAF-mutated non-melanoma solid tumors, and BRAF-mutated classical hairy cell leukemia). Up to approximately 42 patients may be enrolled in the dose escalation phase of the study, depending on the number of cohorts required, number of patients per cohort needed, and the need for replacement patients. Approximately 130 patients are planned to be enrolled in the BRAF-mutated tumor Extension cohorts, with the goal of enrolling approximately 50 patients with BRAF/MEK/ERK inhibitor-naïve melanoma, approximately 10-15 patients with BRAF/MEK/ERK inhibitor-pretreated melanoma, approximately 50 patients with non-melanoma solid tumors, and approximately 10-15 patients with hairy cell leukemia.