Heteroaryl-fused pyrimidinyl compounds, pharmaceutically acceptable salts, and prodrugs thereof; compositions that include a pharmaceutically acceptable carrier and one or more of the heteroaryl-fused pyrimidinyl compounds, either alone or in combination with at least one additional therapeutic agent. Methods of using the heteroaryl-fused pyrimidinyl compounds, either alone or in combination with at least one additional therapeutic agent, in the prophylaxis or treatment of proliferative diseases.