Study of the Selective PI3K-Beta Inhibitor GSK2636771 in Combination With Pembrolizumab in Patients With Metastatic Melanoma and PTEN Loss

The goal of this clinical research study is to learn if GSK2636771 given in combination with pembrolizumab can help to control the disease in patients with refractory (has not responded to treatment) metastatic melanoma. The safety of this drug combination will also be studied. This is an investigational study. Pembrolizumab is FDA approved and commercially available and FDA approved for the treatment of several types of cancer, including melanoma. GSK2636771 is not FDA approved or commercially available. It is currently being used for research purposes only. The study doctor can explain how the study drugs are designed to work. Up to 41 participants will be enrolled in this study. All will take part at MD Anderson.