Abstract LB062: ADT3_A potential first-in-class Vδ1-engager for in situ activation of Vδ1 γδ T cells and enhanced cytotoxicity towards solid tumors

Abstract

Abstract Gamma delta (γδ) T cells are crucial in stress surveillance for infections and cancer. Studies have shown that tumour-infiltrating γδ T cells are a positive prognostic factor in cancer therapy. While γδ T cells share many characteristics with their αβ T cell counterpart, such as cytotoxic effector functions, they express a distinct TCR that is composed of a γ and a δ chain, belong to the HLA-class-I unrestricted immune cell subset with the ability to discriminate and specifically kill tumor cells via recognition of tumor stress ligands. Clinical trials using Vδ1 γδ T cell therapies have demonstrated promising results in Ph 1 trials, with early signs of favorable efficacy and safety profile.ADT3, is a novel bispecific engager that activates tissue-resident Vδ1+ T cells via (Epidermal Growth Factor Receptor) EGFR crosslinking on tumor cells. VD1 T cells isolated from skin biopsies, when activated, enhance the selective killing of EGFR positive tumor cells through innate mechanisms that recognize stress ligands that are otherwise absent on healthy cells. As a bispecific engager, ADT3 preserves high affinity binding to VD1 TCR through the Fab end of the molecule, and binding to two EGFR binding sites via the modified Fc domain. Crosslinking of VD1 and EGFR+ tumor cells with ADT3, mediates a series of events leading to proliferation of VD1 cells, upregulation of activation markers, CD107a degranulation and secretion of chemokines and cytokines (such as TNFa and IFNg) and tumor kill as determined by its potent cytotoxic activity in a T-cell dependent cellular cytotoxicity assay (TDCC). Apart from direct tumor kill, the secretion of such cytokines and chemokines via ADT3 activation are required for induction of immune orchestration of non-Vδ1 immune cells to enhance tumor kill. Preclinical data supports future clinical entry of ADT3, and IND enabling studies are in progress Citation Format: Joshua Freedman, Georgia Stevens, Julie Julie Hoong, Mihirban Tuna, Yaoyao Shi, Kathy J. Seidl, Katherine Galvin, Andrew Hutton, Antara Banerjee. ADT3_A potential first-in-class Vδ1-engager for in situ activation of Vδ1 γδ T cells and enhanced cytotoxicity towards solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB062.