Used primarily in the treatment of acute lymphoblastic leukemia (ALL), 6-Mercaptopurine works as an antimetabolite that interferes with DNA and RNA synthesis in rapidly dividing cells, particularly cancer cells. It is often part of long-term maintenance therapy to prevent relapse. Also used in managing inflammatory bowel diseases like Crohn’s disease and ulcerative colitis, where it modulates the immune system to reduce inflammation. Its immunosuppressive properties make it valuable in controlling autoimmune responses when conventional therapies are ineffective. Requires careful monitoring due to potential liver toxicity and bone marrow suppression.