The thiopurine drugs are purine antimetabolites widely used in the treatment of acute lymphoblastic leukemia, autoimmune disorders (e.g., Crohn's disease, rheumatoid arthritis), and organ transplant recipients.
Metabolism is catalyzed by S-methyltransferase and nudix hydrolase 15 (NUDT15).[1]
Litigation over patents covering diagnostic kits to monitor the dosing of these drugs led to a US Supreme Court case, Mayo Collaborative Services v. Prometheus Laboratories, Inc. that dramatically changed the nature of patent law in the United States.[2][3]