ERBB2 and Thrombocytopenia: Fig 7B summarizes the concept of exploiting Her2 avidity to achieve selective binding and cytotoxicity using weak-affinity ADCs. The low binding and minimal toxicity of weak-affinity ADCs in low-Her2 cells should enhance their safety profile and mitigate against Her2-mediated adverse effects, such as hepatotoxicity noted for T-DM1 [23]. At the same time, it is recognized that T-DM1 can elicit off-target effects attributed to its payload, e.g. thrombocytopenia and elevated liver transaminases [24–28].