ERBB2 and breast carcinoma: The role of pharmacogenetic polymorphisms of CD16A on the efficacy of trastuzumab has been reported in two retrospective studies that suggest that patients with HER2-positive breast cancer with a low-affinity F allele have a poorer response with trastuzumab (in PFS and OR) than patients homozygous for the higher affinity V allele [50,51].