The present invention provides a pyrimidine nucleoside compound represented by the following formula (1):
[wherein one of X and Y is cyano and the other is hydrogen; and i) R
1
is hydrogen, and R
2
is alkyloxycarbonyl wherein the alkyl moiety is straight or branched C
5-12
alkyl (the alkyl may be substituted), or alternatively, ii) R
1
is alkyloxycarbonyl wherein the alkyl moiety is straight or branched C
9
alkyl or alkenyloxycarbonyl wherein the alkenyl moiety is straight or branched C
9
alkenyl, and R
2
is hydrogen] or a salt thereof. The pyrimidine nucleoside compound or a salt thereof of the present invention shows a higher antitumor effect than existing pyrimidine nucleoside compounds.
The present invention provides a pyrimidine nucleoside compound represented by the following formula (1):
[wherein one of X and Y is cyano and the other is hydrogen; and i) R
1
is hydrogen, and R
2
is alkyloxycarbonyl wherein the alkyl moiety is straight or branched C
5-12
alkyl (the alkyl may be substituted), or alternatively, ii) R
1
is alkyloxycarbonyl wherein the alkyl moiety is straight or branched C
9
alkyl or alkenyloxycarbonyl wherein the alkenyl moiety is straight or branched C
9
alkenyl, and R
2
is hydrogen] or a salt thereof. The pyrimidine nucleoside compound or a salt thereof of the present invention shows a higher antitumor effect than existing pyrimidine nucleoside compounds.