Uprosertib, Dabrafenib, and Trametinib in Treating Patients With Stage IIIC-IV Cancer

PRIMARY OBJECTIVES: I. To assess the safety of dabrafenib mesylate (dabrafenib) in combination with uprosertib (GSK2141795) and select the optimal dose of GSK2141795 for the phase II portion in patients with BRAF mutant cancer. (Effective November 15, 2014, this trial will not proceed to the phase II study of dabrafenib and GSK2141795, but will move to an evaluation of triple therapy). (Phase I) II. To assess the safety of dabrafenib and trametinib dimethyl sulfoxide (trametinib) and GSK2141795 in combination and select the optimal dose of the combination for the phase II portion in patients with BRAF mutant cancer. (Phase I) III. To evaluate the objective response rate (confirmed and unconfirmed, complete and partial responses) in patients with BRAF\^V600 mutant metastatic melanoma who have previously progressed on BRAF\^V600 inhibitor-based therapy (BRAFi), or BRAFi + MEK inhibitor-based therapy (MEKi). (Phase II) SECONDARY OBJECTIVES: I. To estimate overall survival and progression-free survival. II. To assess the toxicity profile of the recommended phase II dose. III. To assess response (complete and partial, confirmed and unconfirmed) of patients enrolled on each phase I portion). TRANSLATIONAL MEDICINE OBJECTIVES: I. To explore the molecular mechanisms of acquired resistance to BRAF inhibitor therapy using available biopsies of lesions that progressed during prior BRAF inhibitor-based therapy. II. To explore potential drug-drug interactions between dabrafenib and GSK2141795 leading to changes in the expected exposure with either agent compared to prior experience. (Phase I) OUTLINE: This is a phase I, dose-escalation study of uprosertib followed by a phase II study. Dose escalation of dabrafenib mesylate, trametinib dimethyl sulfoxide, and uprosertib will be initiated after completion of the dabrafenib + uprosertib phase I dose escalation. Dabrafenib mesylate and uprosertib (Phase I): Patients receive dabrafenib orally (PO) twice daily (BID) and uprosertib PO once daily (QD) on days 1-28. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity. Patients undergo a computed tomography (CT) scan, magnetic resonance imaging (MRI), and blood sample collection throughout trial. Patients may also undergo a biopsy throughout the trial. Dabrafenib mesylate, trametinib dimethyl sulfoxide, and uprosertib (Phase I and Phase II): Patients receive dabrafenib PO BID, trametinib PO QD, and uprosertib PO QD on days 1-28. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity. Patients undergo a CT scan, magnetic MRI, and blood sample collection throughout trial. Patients may also undergo a biopsy throughout the trial. After completion of study treatment, patients are followed up every 3 months for 1 year and then every 6 months for 2 years.