Abstract: A description is given of conjugates of vinca alkaloid of the indole-dihydroindole type with a protein or a protein fragment, corresponding to the general formula ##STR1## in which R.sub.1 denotes a protein or a protein fragment;R.sub.2 is COO(C.sub.1-3 alkyl) or CO-R.sub.7 where R.sub.7 isNH.sub.2 or an amino acid ester or peptide ester;R.sub.3 is H, CH.sub.3 or CHO;when R.sub.5 and R.sub.6 are taken separately, R.sub.6 is H and one of R.sub.4 and R.sub.5 is ethyl and the other is H or OH;when R.sub.5 and R.sub.6 are taken together with the carbon atoms to which they are attached, they form an oxirane ring and R.sub.4 is ethyl, andA is a residue of a bifunctional organic derivative of the maleoylamino acid or maleoyl peptide or maleoylphenoxy type.

Abstract: A description is given of conjugates of vinca alkaloid of the indole-dihydroindole type with a protein or a protein fragment, corresponding to the general formula ##STR1## in which R.sub.1 denotes a protein or a protein fragment;R.sub.2 is COO(C.sub.1-3 alkyl) or CO--R.sub.7 where R.sub.7 is NH.sub.2 or an amino acid ester or peptide ester;R.sub.3 is H, CH.sub.3 or CHO;when R.sub.5 and R.sub.6 are taken separately, R.sub.6 is H and one of R.sub.4 and R.sub.5 is ethyl and the other is H or OH;when R.sub.5 and R.sub.6 are taken together with the carbon atoms to which they are attached, they form an oxirane ring and R.sub.4 is ethyl, and A is a residue of a bifunctional organic derivative of the maleoylamino acid or maleoyl peptide or maleoylphenoxy type.

Abstract: Vinblastine derivatives of the formula ##STR1## wherein R.sub.1 is an ester of a .alpha.-aminoacid selected from the group consisting of glycine, alanine, valine, leucine, isoleucine, serine, threonine, aspartic acid, glutamic acid, aspargine, glutamine, arginine, lysine, cysteine, cystine, methionine, phenylalanine, tyrosine, tryptophan, proline, histidine, hydroxy-lysine, hydroxyproline, or of a peptide consisting of 1-6 identical or different such amino-acids, and the ester group, which may be straight or branched, being a carboalkoxy group having 2-9 carbon atoms, and R.sub.2 is hydrogen or a C.sub.2 -C.sub.9 alkanoyl group, R.sub.5 is H or OH, R.sub.6 is CH.sub.3, CHO or H and X=H or Br and their pharmaceutically acceptable mineral or organic acid addition salts. The compounds are useful as antitumor drugs.

Abstract: Amino acid derivatives of vinblastine, including peptide derivatives, methods of their preparation and pharmaceutical compositions containing such vinblastine derivatives for use as antitumor agents are described.