Pharmaceutical composition for inhibiting the metastasis or preventing the recurrence of malignant tumor

A method for inhibiting the metastasis or preventing the recurrence of a malignant tumor in a patient in need thereof, said method comprising:

• administering as the active ingredient a polysaccharide derivative to said patient, wherein said polysaccharide derivative comprises:
• a polysaccharide having a carboxyl group bound to an active substance having an anti-tumor activity via an amino acid or a peptide consisting of 2 to 8 amino acids which are the same or different, or a salt thereof;
• wherein the polysaccharide having a carboxyl group is a carboxy-C1-4 alkyldextran or a carboxy-C1-4 alkyldextran polyalcohol;
• wherein said active substance is a camptothecin derivative of the formula (I):
• wherein R1 is a substituted or unsubstituted lower alkyl group,
• X1 is a group of the formula:
• —NHR2 (R2 is a hydrogen atom or a lower alkyl group), and
• Alk is a straight chain or branched chain C1-6 alkylene group having optionally an oxygen atom in the chain thereof,
• or a compound of the formula (II):
• wherein two groups of R2 to R6 in formula (II) being adjacent each other combine to form a lower alkylene group, and one of the carbon atoms of said lower alkylene group is substituted by an amino group, and the remaining three groups of R2 to R6 are a hydrogen atom, a lower alkyl group or a halogen atom;
• and
• wherein the peptide is a member selected from the group consisting of glycyl-glycyl-L- or D-phenylalanyl-glycine, glycyl-glycine, glycyl-glycyl-glycine, glycyl-glycyl-glycyl-glycine, glycyl-glycyl-glycyl-glycyl-glycine, L- or D-phenylalanyl-glycine, L- or D-tyrosyl-glycine, L- or D-leucyl-glycine, L- or D-phenylalanyl-citrulline and L- or D-valyl-citrulline.