The disclosure provides new anti-cancer compositions that include a Her2 peptide that targets the Her2 receptor and comprises amino acid sequence GSGKCCYSL (SEQ ID NO:1)； and a covalently-linked cytotoxic agent including artemisinin (Art) or a derivative thereof linked to the peptide. Biological assays have demonstrated that the Art-Her2 peptide conjugates described herein show excellent selective cytotoxic activity towards Her2-positive cancers, such as colon cancer, compared to normal colon cells.
