This is a global, multi-centre, open-label, study of GSK2118436 conducted in up to 30 evaluable subjects with resectable, BRAF V600E or V600K mutation-positive metastatic melanoma to the brain. All subjects in this study are required to have accessible extracranial metastases and are agreeable to undergo repetitive biopsies. The first cohort of 15 subjects will receive dabrafenib orally 150mg twice daily (BID) for 7 to 14 days prior to surgery (Cohort A); the second cohort of 15 subjects will receive the combination of dabrafenib 150 mg BID and trametinib 2 mg once daily for 7 to 14 days prior to surgery (Cohort B). The primary purpose of this study is to determine levels and distribution of dabrafenib, its metabolites, and trametinib (Cohort B only) in parenchymal brain metastases, extracranial metastases, and peripheral blood (plasma) within two cohorts of subjects with BRAF V600E/K mutation-positive melanoma that has metastasized to the brain. All subjects will be followed for survival and new anti-cancer therapy for a total of two years or until death or the subject wishes to withdraw from further follow-up.