1) Antineoplastic 2) Antineoplastic drug 3) Cancer drug 
An anticancer drug that belongs to the family of drugs called antimetabolites.
<chemical> 2-amino-1,7-dihydro-6h-purine-6-thione. An antineoplastic compound which also has antimetabolite action. The drug is used in the therapy of acute leukaemia. ... Pharmacological action: antimetabolites, antineoplastic. ... Chemical name: 6H-Purine-6-thione, 2-amino-1,7-dihydro- ... (12 Dec 1998) ... 
(thi″o-gwah´nēn) a guanine analogue in which sulfur replaces the oxygen atom of guanine; used as an antineoplastic agent almost exclusively in the treatment of acute myelogenous leukemia and acute lymphoblastic leukemia. Called also 6-thioguanine and 6-TG.
[n] - an antineoplastic drug used to treat acute leukemias
noun an antineoplastic drug used to treat acute leukemias