Abstract 140: Allogeneic CAR-iNKT cell therapy targeting CLDN18.2-positive gastric and pancreatic cancers.

Abstract Allogeneic cell therapy offers the advantage of immediate and scalable access to healthy and potent effector cells for the treatment of solid tumors, overcoming patient immune dysfunction and potential manufacturing delays, while enabling durable anti-tumor responses. Invariant natural killer T (iNKT) cells are a rare, specialized subset of unconventional T cells that represent an ideal allogeneic cell therapy platform. They express a semi-invariant T cell receptor (iTCR) that recognizes glycolipid antigens presented by the monomorphic, MHC-like molecule, CD1d. Previous studies have shown that iNKT cells do not induce acute graft-versus-host disease, and iNKT cells engineered to express chimeric antigen receptors (CARs) have demonstrated therapeutic potential. In addition to tumor recognition via the CAR, iNKT cells can engage tumors via the endogenous iTCR binding to glycolipid-bound CD1d and via the NKG2D receptor. CAR-iNKT cells offer distinct advantages in the treatment of solid tumors due to their natural ability to home to tissues, infiltrate tumors, and modulate the tumor microenvironment. Claudin 18.2 (CLDN18.2) has emerged as a high-priority target for novel cancer therapies. Under normal physiological conditions, its expression is limited to tight junctions between epithelial cells and remains inaccessible on the cell surface. However, in several malignancies, including gastric, esophageal, and pancreatic cancers, CLDN18.2 becomes surface-exposed as tumor cells lose normal tissue architecture during growth and invasion. This aberrant presentation in malignant tissue makes CLDN18.2 an attractive target for CAR-directed cell therapies. Here, we present the first PBMC-derived CAR-iNKT cell therapy product targeting CLDN18.2. This second-generation CAR features a short chain variable fragment (scFv) derived from SPX-101, a novel monoclonal antibody engineered for enhanced affinity and selectivity for CLDN18.2. To support iNKT cell function, membrane-bound IL-12 (IL-12-TM) was incorporated to provide cytokine armouring, which has been shown to enhance CAR-iNKT cell activity. In this work, iNKT cells were isolated from healthy donor PBMCs, activated, transduced to express the CLDN18.2 CAR with and without IL-12-TM co-expression, and expanded in culture. Cytotoxic activity and effector expansion were evaluated using a serial tumor re-challenge assay against CLDN18.2-positive gastric and pancreatic cancer cell lines. CLDN18.2 CAR-iNKT cells exhibited potent and sustained cytotoxic activity against CLDN18.2-positive tumor cells, and co-expression of IL-12-TM improved the persistence and durability of response under repeated high tumour burden. These findings support the potential of cytokine-armoured CLDN18.2-directed CAR-iNKT cells as an allogeneic cell therapy for the treatment of gastric and pancreatic cancers. Citation Format: Clinton M. Heinze, Elisa Landoni, Michelle Ferguson, Nicole van der Weerden, Robson Dossa, Simon Poon, Kelvin Yip, Jacqui Cumming, Alfie Baker, Sandford Sarah, Michael J. Baker, Barbara Savoldo, Gianpietro Dotti. Allogeneic CAR-iNKT cell therapy targeting CLDN18.2-positive gastric and pancreatic cancers abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 140.