Abstract B009: New development of monoclonal antibodies targeting TRAIL agonist receptors

Restoring programmed-cell death of cancer cells is a real challenge in oncology. To date, several monoclonal antibodies targeting TRAIL agonist death receptors have been developed, but none has been found to display significant clinical effects, so far. Efforts should be continued to develop novel DR4 and DR5 antibodies with improved properties. In this regard, novel monoclonal antibodies targeting DR4 and DR5 have been generated here using DNA-immunization in order to produce antibodies that can recognise DR4 or DR5 in their native forms. This cost- and time-effective technique allows the production of proteins of interest directly into the mice. Plasmids encoding DR4 or DR5 sequences have been injected into the tail veins of mice. Immunizations elicited significant humoral anti-DR4 and anti-DR5 responses and fusions of the corresponding spleens resulted in numerous hybridomas that can specifically recognise DR4 or DR5 in their native forms. After an intensive screening, anti-DR4 and anti-DR5 clones were selected for production and 4 to 5 were assessed for selectivity and affinity towards their respective targets by flow cytometry (FACS) and bio-layer interferometry (BLI). All antibodies efficiently bind to their targets with a very high affinity (nanomolar range). They were then characterized and tested for their capacity to induce apoptosis in a wide range of cancer cell lines. Of the four anti-DR4 antibodies of interest, one antibody displayed agonistic properties alone, one was able to inhibit and two were found to potentiate TRAIL-induced apoptosis. Similarly, one out of the four anti-DR5 antibodies behaved as an agonist whereas another one was found to enhance TRAIL. The most potent antibody was assessed in vivo, and preliminary results indicate that the latter is also able to inhibit tumor growth in animal models. In summary, this study is the first demonstration that DNA-based immunization method can be used to generate efficient therapeutic monoclonal antibodies targeting receptors of the TNF superfamily. Citation Format: Agathe Dubuisson. New development of monoclonal antibodies targeting TRAIL agonist receptors [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B009.