GZMB and neoplasm: Consistently, the loss of HER2 on the knockout tumor cells led to dramatically reduced T cell secretion of IFN-λ and granzyme B in the presence of the HER2-CD3-Fc bsAb (Figure 5D,E and Figure S5D,E), indicating that HER2 binding was required for the bsAb-mediated cytotoxic T cell activation.