I study the signaling required for T cell activation and inhibition, and how these “costimulatory” signaling pathways regulate immune responses. My lab helped discover and elucidate the functions of key T cell costimulatory pathways, including the immune-inhibitory functions of the CTLA-4 and PD-1 pathways, which have become highly effective targets for cancer immunotherapy. We study how costimulatory pathways prevent auto-immunity and regulate antimicrobial and antitumor immunity, and are investigating potentially new therapies for autoimmune diseases, chronic viral infections, and cancer.

I am the George Fabyan Professor of Comparative Pathology and Co-Director of the Evergrande Center for Immunologic Diseases and the Harvard Institute of Translational Immunology at Harvard Medical School, where I also received my M.D. and Ph.D. I have published over 300 papers and was listed by Thomson Reuters as one of the most Highly Cited Researchers (top 1%) in 2014. I am a vice president of the American Association of Immunologists and received the William B. Coley Award for Distinguished Research in Tumor immunology in 2014 for my contributions to the discovery of PD-1 pathway.