Study to Determine the Effectiveness of GSK1120212 in BRAF Mutation-positive Melanoma Previously Treated With or Without a BRAF Inhibitor

Inclusion Criteria:

Metastatic cutaneous melanoma that was previously treated with: (Cohort A) a BRAF inhibitor either with or without other prior therapy. (Cohort B) at least 1 prior chemotherapy or immunotherapy, without treatment with a BRAF inhibitor.
Documented positive BRAF mutation (V600E, V600K, or V600D).
Subjects must provide archived tumor tissue or undergo fresh tumor biopsy prior to enrollment.
The subject must have a radiographically measurable tumor.
The subject is able to carry out daily life activities without significant difficulty (ECOG performance status score of 0 or 1).
Able to swallow and retain oral medication.
Sexually active subjects must use acceptable methods of contraception during the course of the study.
Adequate organ system function and blood cell counts.

Exclusion Criteria:

The subject has had major surgery or received certain types of cancer therapy within 21 days before starting the study.
Previous treatment with a MEK inhibitor.
Current use of a prohibited medication listed in the protocol.
Uncontrolled glaucoma.
Brain metastasis, unless previously treated with surgery or stereotactic radiosurgery, and the disease has been stable for at least 2 months prior to enrollment.
Current severe or uncontrolled systemic disease.
History of clinically significant heart, lung, or eye/vision problems.
Significant unresolved side effects from previous anti-cancer therapy.
The subject is pregnant or breastfeeding.