GSK1120212 vs Chemotherapy in Advanced or Metastatic BRAF V600E/K Mutation-positive Melanoma

Inclusion Criteria: * ≥18 years of age * Stage III unresectable (Stage IIIc) or metastatic (Stage IV) cutaneous melanoma which is also determined to be BRAF V600E/K mutation-positive by the central laboratory * Received no prior treatment or up to one prior regimen of chemotherapy for advanced or metastatic melanoma. Prior treatment with immunotherapy (with the exception of prior ipilimumab, which is only allowed if given in the adjuvant setting), cytokine therapy, biological or vaccine regimen is permitted. Prior use of sorafenib is allowed * Measurable disease according to Response Evaluation Criteria in Solid Tumors (RECIST 1.1) * Women of childbearing potential and men with reproductive potential must agree to use effective contraception during the study. Additionally women of childbearing potential must have a negative serum pregnancy test within 14 days prior to randomization * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0-1 * Adequate screening organ function Exclusion Criteria: * Any prior use of BRAF inhibitors or MEK inhibitors. * Subjects who have received dacarbazine or paclitaxel prior to randomization will not be eligible to receive the same chemotherapy as study medication (i.e. a subject who received prior dacarbazine cannot receive dacarbazine on this trial and would thus receive paclitaxel if randomized to the control arm) * History of another malignancy. Exception: Subjects who have been disease-free for 3 years, or subjects with a hi…