In vitro margetuximab treatment of peripheral blood mononuclear cells (PBMCs) in the presence of HER2+ tumor cells results in enhanced release of IFN-γ compared to trastuzumab (Supplementary Fig. 9a), with ensuing IFN-γ-dependent upregulation of PD-L1 on the co-cultured tumor cells (Supplementary Fig. 9b). Here, ERBB2 is linked to neoplasm.