Nir Hacohen

Nir Hacohen, PhD is a Professor of Medicine at Harvard Medical School, Director of the Center for Cancer Immunology at Massachusetts General Hospital, and a core member of the Broad Institute. He is a leading authority on the genetics of tumor-immune interactions, neoantigen biology, and the dynamic evolution of tumor immunogenicity during immunotherapy. His group made foundational contributions to establishing the concept that clonal neoantigens — those arising from truncal mutations present in all tumor cells — are the primary targets of productive anti-tumor T cell responses and the critical determinants of checkpoint immunotherapy benefit. His work demonstrated that tumors can evolve immune resistance through neoantigen depletion: the selective loss of truncal neoantigen-encoding mutations under immune pressure, which occurs even as total TMB remains high. This clonal neoantigen evolution concept fundamentally challenged TMB as a biomarker by showing that mutation quantity is less important than the clonality and persistence of immunogenic mutations. Dr. Hacohen also co-pioneered personalized mRNA neoantigen cancer vaccines with Moderna and led genomic frameworks for neoantigen prediction, HLA typing, and T cell epitope validation that are now widely adopted in the field.