Expression and prevalence of CLDN18.2 in normal tissues and GI adenocarcinomas. A, Normal tissue RNA expression of CLDN18 [represented as normalized transcripts per million (TPM); Human Protein Atlas, GTEx dataset]. HC, hippocampal formation. CLDN18.2 expression on representative images of the human stomach, NSG mouse stomach, and human lung are shown. B, CLDN18.2 expression on representative samples of gastric cancer (H-score = 249), PDAC (H-score = 175), and esophageal adenocarcinoma (H-score = 175). C, Prevalence and intensity of CLDN18.2 expression on tumor samples derived from patients with gastric cancer (n = 185), PDAC (n = 61), and esophageal adenocarcinoma (n = 32). Data are shown as H-scores and as the percentages of tumor cells at each level of intensity (1+, 2+, and 3+). EAc, esophageal adenocarcinoma; GC, gastric cancer.
ARTICLE ABSTRACT
Claudin 18.2 (CLDN18.2) is a surface membrane protein that is crucial for maintaining tight junctions in gastric mucosal cells and is highly expressed in gastric, esophageal, and pancreatic cancers. Thus, CLDN18.2 is suited for exploration as a clinical target for chimeric antigen receptor T-cell (CAR-T) therapy in these indications. Although CAR-T therapies show promise, a challenge faced in their development for solid tumors is the immunosuppressive tumor microenvironment, which is often characterized by the presence of immune and stromal cells secreting high levels of TGFβ. The addition of TGFβ armoring can potentially expand CAR-T activity in solid tumors. We report on the preclinical development of a CLDN18.2-targeting CAR-T therapy showing effectiveness in patient models with CLDN18.2-positive gastric, esophageal, and pancreatic tumors.
The lead lentivirus product contains a unique single-chain variable fragment; CD28 and CD3z costimulatory and signaling domains; and dominant-negative TGF-β receptor armoring, enhancing targeting and safety and counteracting suppression. We developed a shortened cell manufacturing process to enhance the potency of the final product AZD6422.
AZD6422 exhibited significant antitumor activity and tolerability in multiple patient-derived tumor xenograft models with various CLDN18.2 and TGF-β levels, as determined by IHC. The efficacy of armored CAR-T cells in tumor models with elevated TGFβ was increased in vitro and in vivo. In vitro restimulation assays established greater persistence and cytolytic function of AZD6422 compared with a traditionally manufactured CAR-T.
AZD6422 was safe and efficacious in patient-derived, CLDN18.2-positive murine models of gastrointestinal cancers. Our data support further clinical development of AZD6422 for patients with these cancers.
