ERBB2 and cancer: It is consisted of a humanized mAb targeting HER2 linked to DM1 through a non-cleavable linker (succinimidyl‐4‐(N‐maleimidomethyl)cyclohexane‐1‐carboxylate, SMCC) with an average DAR of 3.5.133 The linker could keep the conjugate more stable in plasma circulation but release payloads after endocytosis in the HER2‐positive cancer cells.