- MK-2206 and AZD6244 hydrogen sulfate are selective inhibitors of human AKT and MEK, respectively, with preclinical and clinical anti-tumor activity as single agents and in combination with a variety of drugs. Combination treatment in mouse cancer models harboring mutations in both the PI3K and RAS (Rat Sarcoma) pathways was more potent compared to either agent used alone, and resulted in substantial tumor inhibition, including tumor regression. The combination is being studied in a Phase I trial and appears tolerable.