Abstract: Novel bis-dioxopiperazine derivatives represented by the following formula (I) and having a broader antitumor spectrum as well as pharmaceutical compositions containing the compounds as antitumor active components: ##STR1## wherein R.sup.1 represents a lower alkyl group; A represents an oxygen atom, a sulfur atom or a group of ##STR2## wherein R.sup.2 represents a hydrogen atom, a lower alkyl group or phenyl; R.sup.3 represents a lower alkyl group, phenyl or benzyl; and X and Y, which are respectively independent and are the same or different, represent a hydrogen atom or a lower alkyl group.

Abstract: Novel bis-dioxopiperazine derivatives or pharmaceutically acceptable salts thereof having broader antitumor spectra and represented by the following formula (I): ##STR1## wherein R.sup.1 represents a lower alkyl group;R.sup.2 represents a hydrogen atom or a group of ##STR2## and R.sup.3 represents a lower alkyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted furyl group, a substituted or unsubstituted styryl group or a group of --(CH.sub.2).sub.n --R.sup.4, ##STR3## or --OR.sup.7 in whichR.sup.4 represents a carboxyl group, a substituted or unsubstituted phenyl group or a substituted or unsubstituted phenoxy group,R.sup.5 and R.sup.6 respectively represent a hydrogen atom or a protective group for amino group,R.sup.7 represents a lower alkyl group or a substituted or unsubstituted benzyl group, andn is an integer and 1 or 2.

Abstract: Disclosed are novel bis-dioxopiperazine derivatives and non-toxic salts thereof, process for their preparation, antitumor agents comprising them and compositions containing them.