Daniel Speiser graduated in 1982 and received a Doctorate in Medicine in 1986 at the University of Zürich, Switzerland. He then completed a clinical degree in internal medicine, with specialization in clinical immunology and (hemato-) oncology. In the laboratory of Rolf Zinkernagel (future Nobel Laureate), he specialised in infection and tumor immunology. Subsequently, he established his independent career in basic and clinical immunology at the Universities of Geneva, Toronto and Lausanne. Starting in 1990, he accomplished many R&D projects and clinical trials of immunotherapy against cancer, pioneering its introduction in clinical oncology. He demonstrated the in vivo importance of T cell avidity and contributed significantly to the mechanistic elucidation of the graft-versus-leukemia effect, and of autologous T cell reactivity in cancer patients. Daniel Speiser was the first to demonstrate in cancer patients that intratumoral T cells have a molecular and functional “exhaustion” profile, resembling the situation in animals and in patients with chronic infection. His innovative work is possible thanks to sound scientific work and knowledge, directly applied to real-life situations in the clinic.