The present invention discloses the compound of 3,4-Dihydro-3-methyl-4-oxoimidazo[5,1-d]-1,2,3,5-tetrazine-8-carboxylate of general fprmula I, a process for producing it, a pharmaceutical composition comprising it and the use of the compound and its composition in the manufacture of a medicament for the treatment of tumor. Said composition comprises one or more compounds of temezolomide-8-carboxylate of formula I as the active ingredient and conventional pharmaceutical carriers. Said composition may also comprise one or more pharmaceutically acceptable acidic components and optionally secondary alcohol or tertiary alcohol or ester or ether derivatives thereof. Further, said composition may be made into all sorts of conventional dosage forms, in particular the oral dosage forms and topically administered transdermal dosage form. In addition, the invention discloses a method to use these compounds and compositions for treatment of tumor.
