ERBB2 and neoplasm: In the HER2 ++ GC PDX model, tumor growth was inhibited by 66% using repeated LCB‐ADC1 treatments at 5 mg mL−1, 107% by repeated treatments with LCB‐ADC3 at 5 mg mL−1, and tumor‐free CR was observed in all mice in the LCB‐ADC3‐treated group at the end point (Figure 6b).