In vitro cytotoxic studies conducted on SKOV‐3 (ovarian cancer, HER2+) and MDA‐MB‐231 (breast cancer, HER2‐) cells, weaker cytotoxic effects on MDA‐MB‐231. In vivo, SKOV‐3 xenografted mice intratumorally injected, 82% reduction of tumor growth. The gene discussed is ERBB2; the disease is breast cancer.