The present invention concerns a combination of (i) a polypeptide comprising ATIP3 or a biologically active fragment thereof, and (ii) a chemotherapeutic drug that is an antimitotic agent, for simultaneous or sequential use in the treatment of a patient suffering from cancer, e.g. a triple-negative breast cancer. The present invention also relates to a polypeptide comprising ATIP3 or a biologically active fragment thereof, for use in sustaining drug effect, increasing or restoring or enhancing sensitivity of a patient suffering from cancer to a chemotherapeutic drug that is an anti-mitotic agent. The present invention further provides biologically active polypeptides that comprise or consist of fragments of ATIP3, and antibodies binding thereto.
