| abstract |
[3H] Imidazo [5,1-d]-1,2,3,5- tetrazine-4-one derivatives of the formula:- <IMAGE> [wherein R<1> represents hydrogen, or an alkyl, alkenyl or alkynyl group containing up to 6 carbon atoms, each such group being unsubstituted or substituted by from one to three substituents selected from halogen atoms, alkoxy, alkylthio, alkylsulphinyl and alkylsulphonyl groups containing up to 4 carbon atoms, and optionally substituted phenyl groups, or R<1> represents a cycloalkyl group containing from 3 to 8 carbon atoms, and R<2> represents a carbamoyl group optionally N-substituted by one or two groups selected from alkyl and alkenyl groups containing up to 4 carbon atoms, and cycloalkyl groups containing 3 to 8 carbon atoms], are new therapeutically useful compounds possessing antineoplastic and immunomodulatory activity. |