Which of the following drugs is used as an immunosuppressant but lacks anticancer activity?: (A) Methotrexate, (B) 6-Mercaptopurine, (C) Azathioprine, (D) 5-Fluorouracil
Answer is C. Azathioprine is an antimetabolite that is used as an immunosuppressant but not as an anti-neoplastic drug. It is a prodrug and is conveed to its active metabolite (6-mercaptopurine) in the lymphoid cells only.