It's not often that a failed clinical trial leads to a scientific breakthrough. When patients in the UK started showing adverse side effects during a cancer immunotherapy trial, researchers at La Jolla Institute for Immunology (LJI) Center for Cancer Immunotherapy and the University of Liverpool went back through the data and worked with patient samples to see what went wrong. Their findings, published on May 4, 2022 in Nature, provide critical clues to why many immunotherapies trigger dangerous side effects—and point to a better strategy for treating patients with solid tumors. "This work shows the importance of learning from early-stage clinical trials," says La Jolla Institute for Immunology (LJI) Professor Pandurangan Vijayanand, MD, PhD, who co-led the new research with Christian H. Ottensmeier, MD, PhD, FRCP, a professor with the University of Liverpool, The Clatterbridge Cancer Centre NHS Foundation Trust, and adjunct professor at LJI.