Stephen M. Kelsey, M.D., FRCP, FRCPath, is a distinguished hematologist-oncologist with over three decades of leadership in drug development, particularly in oncology and hematology. He earned his medical degree from the University of Cambridge and completed specialist training in hematology at Hammersmith Hospital in London, where he served as a consultant physician. Transitioning to industry in the mid-1990s, Dr. Kelsey held progressive roles at Schering-Plough and Berlex Laboratories, focusing on clinical research in hematologic malignancies. His career advanced rapidly at Millennium Pharmaceuticals (later Takeda), where he rose to Senior Vice President of Translational Medicine for Oncology, and subsequently at Genzyme as SVP and Head of Oncology. Dr. Kelsey's tenure at major pharmaceutical companies underscores his pivotal contributions to transformative therapies. At GlaxoSmithKline (2013–2018), he led the global Oncology R&D organization, advancing multiple assets through clinical stages. Joining Amgen in 2018 as Senior Vice President and Head of Hematology/Oncology Research, he oversaw the development and approval of Blincyto® (blinatumomab), a first-in-class bispecific T-cell engager for acute lymphoblastic leukemia, alongside other key programs in multiple myeloma and lymphoma. With authorship of over 150 peer-reviewed publications and patents, Dr. Kelsey has shaped the oncology landscape through innovative trial designs and strategic pipeline prioritization. In 2021, Dr. Kelsey joined Revolution Medicines Inc. as President, Research and Development, where he directs the company's R&D strategy centered on its pioneering portfolio of mutant-selective Ras(ON) inhibitors for oncology. Under his leadership, Revolution Medicines has advanced clinical-stage assets like RMC-6236 and sotorasib combinations into late-stage trials, positioning the company at the forefront of precision oncology targeting the Ras pathway in cancers such as pancreatic, colorectal, and lung malignancies.