Regarding anti-HER3 antibody patritumab, which is a fully human monoclonal immunoglobulin G1 (IgG1) antibody, our in vitro cell line-based screening using 48 NSCLC cell lines suggested that the anticancer efficacy of patritumab depends on the level of heregulin expression rather than that of HER3 expression [23]. This evidence concerns the gene NRG1 and non-small cell lung carcinoma.