CD70 antibody‐drug conjugate: A potential novel therapeutic agent for ovarian cancer

This study aimed to investigate the cytotoxicity of a cluster of differentiation 70 antibody‐drug conjugate (CD70‐ADC) against ovarian cancer in in vitro and in vivo xenograft models. CD70 expression was assessed in clinical samples by immunohistochemical analysis. Western blotting and fluorescence‐activated cell sorting analyses were used to determine CD70 expression in the ovarian cancer cell lines A2780 and SKOV3, and in the cisplatin‐resistant ovarian cancer cell lines A2780cisR and SKOV3cisR. CD70 expression after cisplatin exposure was determined in A2780 cells transfected with mock‐ or nuclear factor (NF)‐κB‐p65‐small interfering RNA. We developed an ADC with an anti‐CD70 monoclonal antibody linked to monomethyl auristatin F and investigated its cytotoxic effect. We examined 63 ovarian cancer clinical samples; 43 (68.3%) of them expressed CD70. Among patients with advanced stage disease (n = 50), those who received neoadjuvant chemotherapy were more likely to exhibit high CD70 expression compared to those who did not (55.6% [15/27] vs 17.4% [4/23], P < .01). CD70 expression was confirmed in A2780cisR, SKOV3, and SKOV3cisR cells. Notably, CD70 expression was induced after cisplatin treatment in A2780 mock cells but not in A2780‐NF‐κB‐p65‐silenced cells. CD70‐ADC was cytotoxic to A2780cisR, SKOV3, and SKOV3cisR cells, with IC(50) values ranging from 0.104 to 0.341 nmol/L. In A2780cisR and SKOV3cisR xenograft models, tumor growth in CD70‐ADC treated mice was significantly inhibited compared to that in the control‐ADC treated mice (A2780cisR: 32.0 vs 1639.0 mm(3), P < .01; SKOV3cisR: 232.2 vs 584.9 mm(3), P < .01). Platinum treatment induced CD70 expression in ovarian cancer cells. CD70‐ADC may have potential therapeutic implications in the treatment of CD70 expressing ovarian cancer.