When the Cure Already Exists

A conversation with David Fajgenbaum on drug repurposing, rare disease, and why the answers might already be on the shelf

I sat down with David Fajgenbaum for the latest episode of Precision Signals for a deeply personal conversation.

David was a third-year medical student and former Division I quarterback when his organs began to shut down. He was read his last rites five times. The diagnosis was idiopathic multicentric Castleman disease, a rare condition in a gray zone between autoimmunity and malignancy, with no reliable treatment. So David did something extraordinary. He started banking his own blood, ran experiments between hospitalizations, traced a signaling pathway in his own tissue, and identified a decades-old transplant drug that no one had ever tried for Castleman disease.

Last month marked 12 years in remission.

Years ago, I invited David to speak at the FDA’s Oncology Center of Excellence, and he left a mark on our entire team. He challenged us to rethink rare diseases, drug repurposing, and the gap between the knowledge in the literature and the knowledge that actually reaches patients. One story from our conversation captures this well: a 2013 paper showed high PD-L1 expression in angiosarcoma. Three years passed before anyone acted on it. David’s team did. That patient has now been in remission for 10 years on a PD-L1 inhibitor.

Today David co-leads Every Cure, a nonprofit using AI to score every approved drug against every known disease. 4,000 drugs. 18,000 diseases. Millions of combinations. The premise is simple and, I think, correct: many of the treatments patients need already exist. The system just hasn’t connected the dots.