Dr. David Fajgenbaum/Every Cure (Philadelphia, Pennsylvania)

15 years ago, a priest read 25-year-old David Fajgenbaum his last rites, as his family said their goodbyes. The third-year medical student had Castleman disease, a rare and often fatal immune disorder. Experimental chemotherapy worked initially, but there was no approved treatment for the disease. Dr. Fajgenbaum took fate into his own hands and repurposed an existing drug to save his life. Now, more than 11 years in remission, he is using the same approach to save others through his biotech organization, Every Cure, highlighted by CNN Chief Medical Correspondent Dr. Sanjay Gupta.