In this study, antitumor efficacy of m708.5 was further evaluated against neuroblastoma and breast cancer cells in combination with several chemodrugs, including EGFR inhibitor gefitinib in vitro and in vivo. The present results indicate that either gefitinib or m708.5 inhibits the cell growth of neuroblastoma (LAN-1) and breast cancer (MCF-7 and SK-BR-3) cell lines. This evidence concerns the gene EGFR and breast carcinoma.