Peptide derivatives

Abstract

A peptide derivative represented by the following formula or a salt thereof ##STR1## wherein A and B each represent either of the following (a) and (b), (a) A represents a hydrogen atom, and B represents a phenyl group substituted with a halogen atom, hydroxyl group, lower alkyl group or lower alkoxy group, or a heteroaryl group, (b) A represents --CONH--R.sup.1, --CSNH--R.sup.1, a hydroxymethyl group, a lower alkoxycarbonyl group or a carboxyl group, wherein, R.sup.1 represents a lower alkyl group or a heteroaryl group, and B represents a phenyl group optionally substituted with a halogen atom, hydroxyl group, lower alkyl group or lower alkoxy group, has an antitumor activity stronger than that of dolastatin 10, and is useful as an anticancer or antitumor agent.

Dependencies are inferred from the claim text.