Although the anti-Her2 position 1-ADC and the anti-Her2 position 2-ADC did not provide superior in vivo tumor efficacy as compared to the anti-Her2 Cys-ADC in HCC-1954 tumors, the anti-Her2 position 1 and anti-Her2 position 2-ADCs contained only half of the amount of drug as the anti-Her2 Cys-ADC. This evidence concerns the gene ERBB2 and hepatocellular carcinoma.