Lillian Siu

Lillian Siu, MD, FRCPC is Senior Staff Physician in the Division of Medical Oncology and Hematology at Princess Margaret Cancer Centre, University Health Network, and Professor of Medicine at the University of Toronto. She is Co-Director of the Phase I Program and founding Director of the IMPACT (Integrated Molecular Profiling in Advanced Cancer Trials) Program — one of the world's most cited and influential precision oncology platforms for molecularly guided phase I trial matching. Dr. Siu is among the most prolific phase I oncologists in North America, having served as principal investigator on hundreds of first-in-human and early-phase trials spanning targeted agents, immunotherapy, antibody-drug conjugates, and bispecific antibodies. Her IMPACT program, launched in 2012, systematically profiles advanced solid tumour patients with next-generation sequencing and matches them to genomically selected phase I trials, providing a rigorous academic framework for biomarker-driven early drug development. Dr. Siu has made landmark contributions to head and neck squamous cell carcinoma (HNSCC) through translational studies characterizing the immune microenvironment and developing predictive biomarkers for PD-1/PD-L1 checkpoint inhibitors. She has led or co-led early-phase trials of pembrolizumab (KEYNOTE-012 HNSCC cohort), nivolumab, and numerous novel immune combination regimens. Dr. Siu has served on international regulatory advisory bodies including Health Canada and FDA advisory panels, and chaired the AACR Phase I/II Trials Working Group. She is a past president of the Canadian Association of Medical Oncologists and a fellow of the Royal College of Physicians and Surgeons of Canada.