To demonstrate the in vivo efficacy of monalizumab in conjunction with intratumoral delivery of human NK cells, transfected HLA‐Ehigh tumor cells were subcutaneously xenografted in Rag2−/‐IL2Rγ−/− immunodeficient mice and 7 days later when tumors reached approximately 40 mm3, mice were intratumorally co‐injected with activated human NK cells with or without monalizumab or control antibody. The gene discussed is IL2RG; the disease is neoplasm.