A Study to Look at the Electrical Activity of the Heart in Subjects With Solid Tumor Cancers, Before and After Receiving the Study Treatment, GSK1120212

A multicenter, non-randomized, placebo-controlled, single dosing schedule, subject-blinded study to evaluate the effect of GSK1120212 on the electrical activity of the heart as compared to placebo in subjects with solid tumor cancers. All subjects will undergo Screening assessments within 21 days prior to the start of the study treatment to determine their eligibility for enrollment in the study. Eligible subjects will receive study treatment administered over a period of 15 days followed by a post-treatment follow-up visit. Study treatment (GSK1120212-matched placebo) will be blinded to subjects. Subjects will receive GSK1120212-matched placebo on one day during the first 14 days of dosing. On all other days the subject will receive a once-daily 2 mg dose of GSK1120212 except for Day 15 when the subject will receive 3mg dose of GSK1120212 12-lead ECG recordings will be obtained from continuous ECG recordings obtained via a 12-lead Holter monitor on Study Days 1 and 15 while subjects are in the clinical research unit. The effect of GSK1120212 on the electrical activity of the heart will be determined by time-matched ECGs obtained at the same time points relative to dosing on these days. Ambulatory blood pressure readings will be obtained from continuous 24-hour recordings via an ambulatory blood pressure monitor The effect of GSK1120212 on blood pressure parameters will be determined by blood pressure readings obtained at the same time points relative to dosing on Study Days 1 and 15. Serial blood samples to analyze the concentration of study drug in the subject's blood will be obtained at the same time points relative to dosing on Study Days 1 and 15. Subjects who are eligible for continued treatment with GSK1120212 may continue treatment under the rollover study MEK114375 (drug study number). A post-treatment follow-up visit will be conducted within 28 days of the last dose of study treatment for all subjects who do not continue treatment in the rollover study MEK