Abstract A038: Inducing tumor associated tertiary lymphoid structures using cellular therapy

Abstract Targeting the tumor microenvironment (TME) to be more immune permissive is a potential strategy for enhancing immunotherapies, such as chimeric antigen receptor T cell (CAR-T) therapy, providing a promising avenue for treating aggressive tumors such as glioblastoma multiforme (GBM). Tertiary lymphoid structures (TLS) are ectopic lymphoid aggregates that arise in response to chronic inflammation and mimic the structure and function of secondary lymphoid organs. The spontaneous presence of TLS in some solid tumors, including GBM, is associated with improved clinical outcome and responsiveness to immunotherapy. I hypothesize that membrane tethered anti-LTβR Sc-Fv (mTa) T cells can function as lymphoid tissue inducer cells (LTi) and interact with lymphoid tissue organizer cells (LTo) in the TME, that express lymphotoxin-β receptor (LTβR), to nucleate TLS. To this end, we screened commercially available murine LTβR agonist antibodies to induce NFκB signaling. When a lead candidate with robust NFkB activation was injected in situ into mice orthotopically injected with a murine glioma cell line, we found multiple TLS-like lymphoid aggregates. We therefore sequenced and cloned a membrane-tethered version of this antibody alongside a CAR construct to generate mTa-CAR-T cells. mTa-CAR T cells could activate LTβR in an NFκB-GFP reporter assay. We proceeded to intratumorally inject these cells into a syngeneic mouse GBM tumor model to evaluate TLS induction and assess the ability of mTa-CAR T cells to improve antitumor efficacy and survival. This study attempts to identify strategies to remodel the TME of GBM and nucleate TLS using cellular therapy to improve the response to CAR-T therapy and survival of GBM patients. Citation Format: Nour Amwas, Darya Alizadeh, Christine Brown, Victor Chiu, Colt Egelston, Diana Gumber, Hanmin Wang, John Williams, Leo David Wang. Inducing tumor associated tertiary lymphoid structures using cellular therapy [abstract]. In: Proceedings of the AACR IO Conference: Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2025 Feb 23-26; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2025;13(2 Suppl):Abstract nr A038.