The present disclosure relates to pharmaceutical compositions comprising a peptide or multivalent polypeptide, and an anti-cancer agent. In some embodiments, the anti-cancer agent is conjugated to the peptide or multivalent polypeptide. The present disclosure also relates to a method of treating cancer or reducing cancer cell proliferation using the peptide or multivalent polypeptide. In some aspects, the peptide or multivalent polypeptide enhances the efficacy of the anti-cancer agent, the targeting of the anti-cancer agent to the cancer cells, or both.