Dr. Irving Weissman is the Virginia and Daniel Ludwig Professor of Clinical Cancer Research and Professor of Pathology and Developmental Biology at Stanford University. Dr. Weissman was the first scientist to identify and isolate mammalian blood-forming stem cells in mice, and his work has contributed to the understanding of how a single hematopoietic stem cell can give rise to specialized blood cells. He talks about developing new treatments for metastatic breast cancer and severe combined immunodeficiency. He also discusses myeloid bias in aging and strategies for commercializing new therapies.