Figure 20. (Left) George Hitchins (1905-1988) and Trudy Elion (1918-1999) at Burroughs Wellcome labs in Tuckahoe NJ. Picture courtesy Burroughs Wellcome) (Right) George Schwartz (1928- fl.) who studied their first purine antimetabolite, 6-mercaptopurine (6-MP) an analogue of hypoxanthine, in the 1950s and showed it depressed immune responses. Hitchins and Elion received the Nobel prize for their work on antimetabolites to treat cancer.