ERBB2 and neoplasm: We assessed cell surface binding and saturation of zanidatamab compared to trastuzumab, pertuzumab and the equimolar tras + pert (1:1 ratio) by flow cytometry to a panel of tumor cell lines which express a range of cell surface HER2 levels, including SK-BR-3 (HER2 3+; Fig. 1c), NCI-N87 (HER2 3+), JIMT-1 (HER2 2+) and MCF7 (HER2 1+) cells (Supplementary Fig. 2).