Focused his research efforts upon the discovery and characterization of inhibitors of angiogenesis and tumor dormancy. He discovered multiple endogenous angiogenesis inhibitors including angiostatin, endostatin, and antiangiogenic antithrombin. Ongoing studies of the influence of tumor microenvironment upon response to angiogenesis inhibitors alone and in combination with other modalities are now underway in Dr. O’Reilly’s laboratory. Dr. O’Reilly and colleagues study the interaction of antiangiogenic agents and other targeted biologics with radiation therapy and chemotherapy in a series of projects designed to produce improved efficacy and diminished toxicity in the treatment of cancer. Dr. O’Reilly’s research work has led to multiple publications and presentations and has provided the basis for clinical trials in lung cancer patients.