Arlene Sharpe is the George Fabyan Professor of Comparative Pathology at Harvard Medical School and co-chair of the Harvard Medical School Department of Immunology. She is one of the world's foremost authorities on co-stimulatory and co-inhibitory immune checkpoint pathways, having contributed foundational discoveries that underpin modern cancer immunotherapy. Sharpe's laboratory was instrumental in elucidating the functions of the PD-1/PD-L1 and CTLA-4 pathways — discoveries that directly enabled the development of checkpoint inhibitor drugs now generating billions in annual revenue. Her group characterized how PD-L1 expression on tumor cells dampens anti-tumor immunity, and demonstrated that PD-1 blockade can restore T cell activity and tumor control. The Sharpe lab uses advanced flow cytometry, single-cell genomics, in vivo mouse tumor models, and multiplex immunohistochemistry platforms — representing a significant buyer of reagents, antibodies, cell analysis equipment, and transgenic mouse services. She has published over 340 papers, holds ten patents related to checkpoint biology, and has received the Jeantet Prize, the William B. Coley Award, and election to the National Academy of Sciences and National Academy of Medicine.