Pharmacological effects of site specific conjugated anti-human epidermal growth factor receptor 2-antibody drug conjugate using unnatural amino acid technology / 北京大学学报(医学版)

ABSTRACT

OBJECTIVE@#To investigate inhibitory activities of a homogenous anti-human epidermal growth factor receptor 2 (HER2)-antibody drug conjugate (ADC) on the proliferation of nine tumor cell lines with different levels of HER2 expressions, and its activities on the tumor growth of five xenograft mouse models.@*METHODS@#The HER2 expression levels of BT-474, Calu-3, MCF-7, MDA-MB-231, MDA-MB-468, SK-BR-3, SK-OV-3, HCC1954, NCI-N87 tumor cell lines were measured using QIFI KIT. For the in vitro anti-proliferation assay, serial diluted anti-HER2-ADC, ado-trastuzumab emtansine, AS269, pAF-AS269 and paclitaxel were added to the seeded cells, and after 72 or 96 hours of incubation, the cell proliferation was analyzed. For the in vivo activity, 5-6 weeks old mice were inoculated with four HER2 positive tumor cell lines HCC1954, BT-474, SK-OV-3, NCI-N87 or one HER2 negative tumor cell line MDA-MB-468. Different amounts of anti-HER2-ADC, ado-trastuzumab emtansine, trastuzumab, paclitaxel and phosphate buffered saline control were injected after the tumor volume reached a certain size, then the tumor growth inhibition was analyzed.@*RESULTS@#The expression levels of the six high HER2-expression cell lines SK-OV-3, NCI-N87, SK-BR-3, Calu-3, HCC1954, BT-474 were between 430 000 to 800 000 receptors per cell, which were 50 times higher than those of the other three low HER2 expression tumor cell lines MDA-MB-231, MCF-7, MDA-MB-468. Anti-HER2-ADC had inhibition effects on cell lines with high level of HER2 expression in the in vitro anti-proliferation assay. The half maximal inhibitory concentrations of anti-HER2-ADC on SK-OV-3, NCI-N87, SK-BR-3, Calu-3, HCC1954, BT-474 tumor cell lines were 46 pmol/L, 17 pmol/L, 17 pmol/L, 161 pmol/L, 125 pmol/L, 50 pmol/L, respectively. Anti-HER2-ADC had a dose dependent antitumor activity in vivo in all the HER2 positive xenograft mouse models. In NCI-N87 xenograft tumor model, the same dose of anti-HER2-ADC showed better anti-tumor activity compared with trastuzumab and ado-trastuzumab emtansine, and its relative tumor proliferation rates were about 1/30 to 1/20 of the two. In HCC1954 xenograft tumor model, the complete regression of the tumor was observed. As expected, anti-HER2-ADC had no tumor inhibitory effects on MDA-MB-468 xenograft models with low HER2 expression. The antitumor activities of anti-HER2-ADC in HER2 positive xenograft tumor models were the same as or better than the activities of ado-trastuzumab emtansine.@*CONCLUSION@#The homogenous site-specific anti-HER2-ADC obtained using unnatural amino acid technology can inhibit the growth of high HER2-expression tumor cells with high potency both in vivo and in vitro.