We demonstrated that the E8 nanobody exhibited excellent targeting ability for gastric cancer imaging and displayed anti‐tumor activity in vivo when fused with the truncated toxin PE38.[11c] However, these nanobodies were unable to bind to murine CDH17 protein, making them unsuitable for testing related drugs in immunocompetent mice inoculated with murine CDH17‐positive tumor cells, such as Colon26, CT26, or PancO2. This evidence concerns the gene CDH17 and neoplasm.