As a medical student, David Fajgenbaum nearly died from Castleman disease, a rare autoimmune condition. He would suffer recurring bouts that carried him to the brink of death but was able to push the disease into remission by discovering a drug that could be repurposed to treat the disease. Fajgenbaum co-founded the Castleman Disease Collaborative Network and developed a unique approach to research that is now being adopted by other rare disease organizations. He tells his story in his book “Chasing My Cure.” When the COVID-19 outbreak began, Fajgenbaum recognized that the deadliest aspect of the disease—a hyperactive immune response known as a cytokine storm—shared a common link with Castleman disease. He hoped that a researcher would apply his approach to finding a potential drug to repurpose to treat the virus and soon enlisted his own team to do so. We spoke to Fajgenbaum, assistant professor at the Perelman School of Medicine at the University of Pennsylvania and co-founder and executive director of the Castleman Disease Collaborative Network, about his own experience, how it led him to work on COVID-19, and his effort to help researchers and clinicians track all of the drugs being tried to treat the pandemic virus.