Abstract 4150: Novel preclinical model for the evaluation of cytokine release syndrome in response to CD19xCD3 bispecific antibody in humanized mice

Abstract

Abstract Cytokine Release Syndrome (CRS) is a systemic inflammatory response that is caused by the large, rapid release of cytokines in the blood by immune cells affected by infection or immunotherapy and remains a prominent challenge for T cell-based therapeutics. Bispecific T cell engagers (BiTEs) are fusion proteins that are generated by linking the targeting region of two antibodies: one arm binds to the tumor-associated antigen, and the other arm binds to T cells to promote T cell-mediated cytotoxicity in an MHC-independent manner. A CD19xCD3 BiTE has been approved by the FDA for the treatment of CD19-positive B-cell lymphoma. Despite having great clinical efficacy, CRS remains a major concern for BiTE therapy. This necessitates the development of a translational model that could predict CRS toxicity more accurately. Various in-vitro models proposed to assess BiTE-related CRS have several shortcomings as they do not provide details about the systemic immune response, off-target effects, neurotoxicity, tissue damage, and organ failure. Here we propose an in-vivo approach to concomitantly assess the efficacy and CRS toxicity of CD19xCD3 BiTE either alone or in combination with Rituximab (monoclonal antibody targeting CD20) in the Raji luciferase xenograft model of Burkitt’s lymphoma in PBMC humanized NSG-MHC Class I/II knockout mice. Five days post human PBMC engraftment (Study Day- SD 5), the mice were injected with Raji-luciferase cells. On SD 6, the mice were treated with BiTE, Rituximab, or the combination of BiTE and Rituximab. Additional control groups included OKT3 and Anti-CD28, the anti-T cell antibodies that failed clinically due to severe CRS. Efficacy was assessed through in-vivo imaging on SD5, SD8, and SD11. We observed tumor growth inhibition with BiTE, Rituximab, and the combination treatment. Clinical observations were recorded daily post treatment. Following cytokines were measured 6 hours after dosing and at study termination - IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ. Elevated cytokine levels were observed in the BiTE/combination group 6 hours post dosing but not in the Rituximab alone group. Together, the data suggest that the model could be used to assess the preclinical efficacy and CRS toxicity of BiTE. Citation Format: Deep S. Shah, Catalina Simion, Sang hu, Rhonda Chronis, Tre McClellan, Jae Hwang, Ryan Yang, Heather Baker, Danying Cai, James Keck, Lindsay Shopland. Novel preclinical model for the evaluation of cytokine release syndrome in response to CD19xCD3 bispecific antibody in humanized mice. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4150.