IGHE and neoplasm: Despite these differences, a xenograft model with severe combined immunodeficient (SCID) mice, and a patient‐derived xenograft model of ovarian carcinoma both reconstituted with human peripheral blood mononuclear cells, were successfully used to demonstrate the superior tumour‐killing potential of MOv18 IgE over IgG1 via both CD23 and FcεRI 59, 107.