A Study to Determine the Relative Bioavailability of the MEK Inhibitor, Trametinib, in Subjects With Solid Tumor Malignancies

This is an open-label, randomized, single-dose, 2-treatment, 2-period, 2-way crossover study with incomplete wash-out in subjects with solid tumors to determine the relative bioavailability of test formulation with lower dimethyl sulfoxide (DMSO) content as compared with standard reference formulation trametinib. Approximately 18 subjects will be randomized to receive either a single dose of Treatment A (standard target DMSO content \[theoretical 11.3%\] formulation of GSK1120212B) or a single dose of Treatment B (lower DMSO Content \[approximately 9.5%\] formulation of GSK1120212B) followed by a 7 day incomplete wash-out period, then a single dose of the other treatment. Administration of the dose under fasted conditions in Periods 1 and 2 will be only on Day 1 followed by 7 days of serial blood sampling for PK analysis of plasma trametinib. Safety assessments, including assessment of AEs, clinical laboratory (hematology and clinical chemistry) and vital signs, will be made throughout the study. After a subject completes the study, he or she may be eligible to enter study MEK114375, an open-label rollover study of trametinib (no wash-out period or follow-up visit required) and continue receiving trametinib. For those subjects who wish to discontinue or complete the current study and choose not enter the rollover study, a follow-up visit should be performed within 21 days after receiving the last dose of study treatment.