Sergio A. Quezada

Sergio A. Quezada, PhD is Professor of Tumour Immunology at University College London Cancer Institute and Director of the Cancer Immunology Unit. He is internationally recognized for his seminal work defining how FoxP3+ regulatory T cells (Tregs) within the tumor microenvironment suppress antitumor immunity, and for elucidating the critical role of intratumoral Treg depletion as a key mechanism of action of anti-CTLA-4 therapy (ipilimumab). Working initially at the Sloan Kettering Institute with James Allison, and subsequently building his own laboratory at UCL, Dr. Quezada demonstrated that anti-CTLA-4 antibodies mediate depletion of intratumoral Tregs via Fc receptor-dependent mechanisms (antibody-dependent cellular phagocytosis/cytotoxicity) on tumor-associated macrophages — a mechanism that is antibody isotype-dependent and distinct from simple CTLA-4 signaling blockade on effector T cells. This work has profound implications for next-generation anti-CTLA-4 antibody engineering: Fc-optimized anti-CTLA-4 antibodies designed to maximize Treg depletion (such as botensilimab) are now in clinical trials with superior efficacy signals. Dr. Quezada has also contributed extensively to understanding neoantigen-specific T cell responses, intra-tumoral T cell clonal dynamics, and personalized cancer immunotherapy. His laboratory applies single-cell multi-omics approaches to dissect TME immune architecture at unprecedented resolution. He has published more than 200 papers and has received multiple awards from major cancer immunology societies.