Abstract 6175: Developing antibody-drug conjugates against cholangiocarcinoma using a novel molecular target

Abstract

Abstract As a rare malignancy, cholangiocarcinoma (CCA) is a lethal disease with a 5-year overall survival rate of merely 5%. Highly invasive and asymptomatic characteristics of CCA cause most patients diagnosed at advanced stages, severely deteriorating their clinical outcomes. The drug treatment options for CCA are limited and surgical resection of CCA frequently suffers from a high recurrence rate of 66%. Albeit Pemigatinib, a FGFR2 inhibitor, has recently been approved by FDA as the first CCA-targeted therapeutic, only less than 10% of patients with CCA carry FGFR2 fusion mutations that can benefit from this drug. Ivosidenib, another targeted drug against IDH1 mutation, only works for 13% CCA patients carrying this mutation. Therefore, discovering new molecular targets and developing associated targeted drugs remain a significant and unmet medical need in CCA therapy. In this study, we first screened potential molecular targets for CCA by comparing the expression levels of a panel of cancer-related cell membrane antigens between human CCA cells and normal human intrahepatic biliary epithelial cells through flow cytometry. CD54 was identified as a remarkable molecular target of CCA with strong binding force to its antibodies and high endocytosis efficiency by flow cytometry and confocal fluorescent microscopy. Meanwhile, we confirmed that CD54 was absent in most normal human tissues but was highly upregulated in CCA tumor tissues through immunohistochemical (IHC) staining. Based on this newly discovered CCA target, we constructed a series of CD54 antibody-drug conjugates (ADCs) using different chemical linkers and payloads. We next evaluated and compared the half maximum inhibitory concentrations (IC50s) of each ADC in ablating human CCA cells in vitro in order to identify an optimized ADC formulation. Furthermore, we validated its anti-tumor efficacy against primary and peritoneal metastatic CCA tumors in vivo in comparison with conventional chemotherapy. Eventually, we determined the biodistribution and safety profile of this CD54 ADC in order to ensure that it is well-tolerated under the effective dose. In general, we identified CD54 as a novel molecular target for CCA through antibody library screening, and explored its potential in the development of CCA-targeted ADCs, providing a promising targeted therapeutic for clinical treatment of CCA. Citation Format: Bing Zhu, Shi-Li Yao, Xin-Yan Wang, Rui Xu, Peng Guo, Jie-Er Ying. Developing antibody-drug conjugates against cholangiocarcinoma using a novel molecular target [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6175.