Investigate Safety, Pharmacokinetics and Pharmacodynamics of GSK2118436 & GSK1120212

This was an open-label, dose escalation study to investigate the safety, pharmacokinetics, pharmacodynamics and clinical activity of GSK2118436 and GSK1120212 in combination. This study was designed in four parts. In Part A, the effect of repeat doses of GSK1120212 on the pharmacokinetics of single dose GSK2118436 was investigated prior to evaluating combination regimens. In Part B, the range of tolerated dose combinations was identified using a dose-escalation procedure. In Part C, different dose combinations of GSK2118436 and GSK1120212 were evaluated, based on results from the dose escalation cohorts. In Part D, the pharmacokinetics and safety of GSK2118436 administered as HPMC capsules alone and in combination with GSK1120212 was evaluated.

During Part A, a cohort of subjects received a single dose of GSK2118436 alone (Day 1) and then repeat doses of GSK1120212 for (Day 2 through Day 15). The dose regimen of GSK1120212 were continuous dosing. A second single dose of GSK2118436 was administered on Day 15 concomitantly with GSK1120212. Day 16 through Day 28 was a washout period, during which no study medication was administered. Starting on Day 29, subjects who elected to continue participation in the study were doses with GSK2118436. The dose of GSK2118436 after Day 29 might be altered based on emerging data from the first-time-in human study BRF112680. The dose might be increased to a dose level that has been completed and determined to be less than or equal to the maximum tolerated dose in that study.

Part B of the study enrolled cohorts in escalating doses to identify a set of allowable doses to be expanded in Part C. Subjects were enrolled in a 3+3 cohort design, with provisional dose levels of both drugs. The decision regarding escalation to the next dose levels of GSK1120212 and GSK2118436 was further guided by a Bayesian logistic regression model. The first cohort started at low doses for both drugs. Doses up to 300 mg/day for GSK2118436 and up to 3 mg QD for GSK1120212 were studied. The starting dose might be lowered based on emerging data from other studies and from Part A.

Expansion cohorts enrolled in Part C at dose levels of GSK2118436 and GSK1120212 as defined in Part B. One of the selected doses might include GSK2118436 administered as monotherapy at a tolerable dose (less than or equal to the maximum tolerated dose) determined in BRF112680. Part C was a randomized open-label Phase II portion of the study, and consisted of expansion cohorts investigating 2 to 3 dose levels of GSK2118436 and GSK1120212 dosing in combination, and GSK2118436 administered as monotherapy. Subjects were assigned to treatment arms in a randomized fashion to compare tolerability and safety. Population PK parameters, clinical activity, durability of response and safety of GSK2118436 and GSK1120212 dosed orally in combination and GSK2118436 as monotherapy were evaluated.

Part D consisted of evaluation of the pharmacokinetics of GSK2118436 HPMC capsules administered as monotherapy and in combination with GSK1120212. Pharmacokinetics of GSK2118436 was assessed following a single dose on Day 1 and after repeat dosing (Day 21) and compared between combination and monotherapy. The pharmacokinetics of GSK1120212 was also be assessed. Safety, tolerability and clinical activity were evaluated in 4 dosing cohorts. These cohorts might be expanded for additional safety data. Subjects were randomized to different cohorts.

Eligibility Criteria:
Key Inclusion Criteria:

* Capable of given written informed consent, which includes compliance with the requirements and restrictions listed in the consent form.
* Male or female age 18 years or greater; able to swallow and retain oral medication.
* BRAF mutation positive melanoma or colorectal cancer; other BRAF mutation positive tumor types may be considered.
* Measurable disease according to RECIST version 1.1.
* Eastern Cooperative Oncology Group Performance Status of 0 or 1 for Parts A and B. Subjects with Eastern Cooperative Oncology Group Performance Status of 2 or less may be entered into Part C with approval of medical monitor.
* Agree to contraception requirements.
* Calcium phosphorus product less than 4.0mmol2/L2.
* Adequate organ system function.

Key Exclusion Criteria:

* Currently receiving cancer therapy (chemotherapy, radiation therapy, immunotherapy, or biologic therapy).
* Part A and Part B: Prior exposure to BRAF or MEK inhibitors unless approved by the GSK Medical Monitor.
* Part C: Prior exposure to BRAF or MEK inhibitors. Prior anti-cancer therapy in the metastatic setting, with the exception of up to one regimen of chemotherapy and/or interleukin-2 (IL-2).
* Part D: Prior exposure to BRAF inhibitors. A washout period of 6 weeks is required for ipilimumab.
* Received an investigational anti-cancer drug within 4 weeks or 5 half-lives (whichever is shorter) of study drug administration--- at least 14 days must have passed between the last dose of prior investigational anti-cancer drug and the first dose of study drug.
* Current use of a prohibited medication or requires any of these medications during treatment with study drug.
* Current use of therapeutic warfarin.
* Any major surgery, radiotherapy, or immunotherapy within the last 4 weeks. Limited radiotherapy within the last 2 weeks.
* Chemotherapy regimens with delayed toxicity within the last 4 weeks. Chemotherapy regimens given continuously or on a weekly basis with limited potential for delayed toxicity within the last 2 weeks.
* Unresolved toxicity greater than National Cancer Institute-Common Terminology Criteria for Adverse Events version 4 Grade 1 from previous anti-cancer therapy except alopecia.
* History of retinal vein occlusion, central serous retinopathy or glaucoma.
* Predisposing factors to retinal vein occlusion including uncontrolled hypertension, uncontrolled diabetes, uncontrolled hyperlipidemia, and coagulopathy.
* Visible retinal pathology as assessed by ophthalmologic exam that is considered a risk factor for retinal vein occlusion or central serous retinopathy.
* Intraocular pressure greater than 21mm Hg as measured by tonography.
* Glaucoma diagnosed within one month prior to study Day 1.
* Presence of active gastrointestinal disease or other condition that will interfere significantly with the absorption, distribution, metabolism or excretion of drugs.
* Known human immunodeficiency virus, Hepatitis B or Hepatitis C infection.
* Primary malignancy of the central nervous system.
* Untreated or symptomatic brain metastasis, leptomeningeal disease or spinal cord compression. Subjects who are on a stable dose of corticosteroids for more than 1 month or off corticosteroids for 2 weeks can be enrolled with approval of medical monitor. Subjects are not permitted to receive enzyme-inducing anti-epileptic drugs.
* Subjects with brain metastases are excluded, unless

  a. All known lesions must be previously treated with surgery or stereotactic radiosurgery, and- b. Brain lesion(s), if still present, must be confirmed stable (i.e. no increase in lesion size) for ≥90 days prior to first dose on study (must be documented with two consecutive MRI or CT scans using contrast), and c. Asymptomatic with no corticosteroids requirement for ≥ 30 days prior to first dose on study, and d. No enzyme-inducing anticonvulsants for ≥ 30 days prior to first dose on study.
* History of alcohol or drug abuse within 6 months prior to screening.
* Psychological, familial, sociological or geographical conditions that do not permit compliance with the protocol.
* QTc interval greater than or equal to 480msecs.
* History of acute coronary syndromes (including unstable angina), coronary angioplasty, or stenting within the past 24 weeks.
* Class II, III, or IV heart failure as defined by the New York Heart Association functional classification system.
* Abnormal cardiac valve morphology (subjects with minimal abnormalities can be entered on study with approval from the medical monitor.
* Treatment refractory hypertension defined as a blood pressure of systolic\> 140 mmHg and/or diastolic \> 90 mm Hg which cannot be controlled by anti-hypertensive therapy
* Patients with intra-cardiac defibrillators or permanent pacemakers.
* Cardiac metastases
* Known immediate or delayed hypersensitivity reaction or idiosyncrasy to drugs chemically related to the study drugs or excipients.
* Pregnant or lactating female.
* Unwillingness or inability to follow the procedures required in the protocol.
* Uncontrolled diabetes, hypertension or other medical conditions that may interfere with assessment of toxicity.
* Subjects with known glucose 6 phosphate dehydrogenase deficiency.