Here we showed that human IL‐2‐Fc (K35E, C125S in human IL‐2; wild‐type IgG1) with IgG1 Fc effector function is equally efficacious as M5A‐IL‐2 ICK in immunocompetent CEA+ breast and colon cancer models. This evidence concerns the gene CEACAM5 and colonic neoplasm.