Similar to previous reports, we found the level of HER2 expression did not correlate with the efficacy of RC48-ADC in CRC PDX models, in line with the notion that HER2 expression level as measured by IHC is not a reliable predicative biomarker for HER2-targeting ADCs and can not be used for patient stratification. This evidence concerns the gene ERBB2 and colorectal carcinoma.