Abstract 2893: Exploring the combinatorial potential of bispecific T-cell engagers in high throughput format

Abstract Bispecific antibodies are being explored as a means to modulate responses of the immune system to tumor infiltration. They are emerging as a growing class of immunotherapies with potential to further improve clinical efficacy and safety. Besides tumor-targeted and dual immunomodulators, the most important class of therapeutically relevant bispecific antibodies are engagers of cytotoxic immune cells to kill tumor cells. These are mainly engager of T-cells (BiTE´s), but also NK-cell engager several of which have entered clinics with Blinatumomab (anti-CD3/anti-CD19) being FDA-approved for the treatment of Acute Lymphoblastic Leukemia. Several studies are under way to address potential combinatorial effects with other compounds in clinics. In order to facilitate analysis of the cytotoxic impact of BiTE´s in high throughput, we developed a 384-well format assay system based on Luciferase-labeled tumor cells. This detection technology has many advantages. As only the tumor cells are labeled, the specific detection of luciferase exclusively correlates to the number of viable tumor cells, allowing for co-cultures with high excess of effector cells without them interfering in the detection. Due to high sensitivity, only few tumor cells are required for a decent signal/noise ratio, keeping the overall need for primary effector cells to the lowest, even at high effector/target cell ratios. That can be of great advantage when working with rare cytotoxic subpopulations (e.g. NK-cells), precious samples from patients, or simply saves resources when performing large exploratory studies. In addition, combination of low 384-well format volumes with nanodrop agent dispensing technology minimizes amounts of expensive antibodies and other agents. Applying this technology, we evaluated the combinatorial effects of Blinatumomab with immune modulators (e.g. Lenalidomide), kinase inhibitors (e.g. MEK-inhibitor, Selumetinib) and other clinically relevant agents (e.g. MCL1-inhibitor, S63845) on the Luciferase-labeled GCB-like DLBCL cell line OCI-LY1. Depending on compound combination, we observe synergistic but also antagonistic effects. Our data support the outstanding usefulness of this methodological approach for the exploration of bispecific cytotoxic immune cell engager agents. Citation Format: Carla N. Castro, Daniel Feger, Sarah Ulrich, Oliver Siedentopf, Jan E. Ehlert. Exploring the combinatorial potential of bispecific T-cell engagers in high throughput format [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 2893.