ERBB2 and neoplasm: Prospective selection of patients was via central testing of tumor specimens using the PATHWAY Anti-HER2/neu (4B5) Rabbit Monoclonal Primary Antibody on the VENTANA BenchMark ULTRA staining instrument (the PATHWAY HER2 (4B5) assay) under an investigational use only (IUO) label, with assessment performed by pathologists trained for HER2-low scoring, using the criteria for distinguishing IHC 0 from IHC 1+ set forth in the ASCO/CAP 2018 guidelines, which were the relevant guidelines at the time of this study [5].