(wherein R
1
and R
4
are the same or different and each represents a hydrogen atom, substituted or unsubstituted lower alkyl, substituted or unsubstituted lower alkynyl, substituted or unsubstituted lower alkenyl, or the like; R
5
represents a substituted or unsubstituted heterocyclic group, substituted or unsubstituted aryl, or the like; R
2
represents —C(═W)R
6
or the like; R
3
represents a hydrogen atom, —C(═W
A
)R
6A
, or the like)
Antitumor agents which comprises a thiadiazoline derivative represented by the aforementioned general formula (I) or a pharmacologically acceptable salt thereof as an active ingredient are provided.
(wherein R
1
and R
4
are the same or different and each represents a hydrogen atom, substituted or unsubstituted lower alkyl, substituted or unsubstituted lower alkynyl, substituted or unsubstituted lower alkenyl, or the like; R
5
represents a substituted or unsubstituted heterocyclic group, substituted or unsubstituted aryl, or the like; R
2
represents —C(═W)R
6
or the like; R
3
represents a hydrogen atom, —C(═W
A
)R
6A
, or the like)
Antitumor agents which comprises a thiadiazoline derivative represented by the aforementioned general formula (I) or a pharmacologically acceptable salt thereof as an active ingredient are provided.
A mitotic kinesin Eg5 inhibitor which comprises a thiadiazoline derivative represented by the general formula (I) or a pharmacologically acceptable salt thereof as an active ingredient:
[wherein R
1
represents a hydrogen atom and the like, R
2
represents a hydrogen atom, —C(═W)R
6
(wherein W represents an oxygen atom or a sulfur atom, and R
6
represents substituted or unsubstituted lower alkyl and the like) and the like, R
3
represents —C(═Z)R
19
(wherein Z represents an oxygen atom or a sulfur atom, and R
19
represents substituted or unsubstituted lower alkyl and the like) and the like, R
4
represents substituted or unsubstituted lower alkyl and the like, and R
5
represents substituted or unsubstituted aryl and the like] and the like are provided.
A mitotic kinesin Eg5 inhibitor which comprises a thiadiazoline derivative represented by the general formula (I) or a pharmacologically acceptable salt thereof as an active ingredient:
[wherein R
1
represents a hydrogen atom and the like, R
2
represents a hydrogen atom, —C(═W)R
6
(wherein W represents an oxygen atom or a sulfur atom, and R
6
represents substituted or unsubstituted lower alkyl and the like) and the like, R
3
represents —C(═Z)R
19
(wherein Z represents an oxygen atom or a sulfur atom, and R
19
represents substituted or unsubstituted lower alkyl and the like) and the like, R
4
represents substituted or unsubstituted lower alkyl and the like, and R
5
represents substituted or unsubstituted aryl and the like] and the like are provided.