Furthermore, margetuximab proved to be more effective than trastuzumab against HER2-positive cancer cells expressing low levels of HER2, or that are resistant to the antiproliferative activity of trastuzumab, as well as in patients with the low-affinity variant of the FcyRIIIa receptor (158F, homozygous or heterozygous), as shown by antibody-dependent cytotoxicity assays [86]. The gene discussed is ERBB2; the disease is cancer.