ERBB2 and neoplasm: Moreover, LCB‐ADC3 showed sufficient antitumor potency with a tumor inhibition rate of 106% and CR in all HER2 ++ GC PDX mice after only a single treatment (Figure S1b, Supporting Information) These results clearly demonstrated that the HER2‐targeting LCB‐ADCs produced by our linker‐drug technology are clinically applicable and address some of the significant shortfalls with current HER2‐targeting therapeutics.