Development of cellular immunotherapy for gastric carcinomas

Introduction:According to the World Health Organization, gastric cancer is the fifth most common and lethal malignancy worldwide.Its distribution in Brazil is heterogeneous, with the highest incidence in the Southern region for both sexes, while in the Northern region, it is the second most frequent cancer among men.Curative treatment relies on gastrectomy, complemented by chemotherapy and monoclonal antibodybased immunotherapy.Since the early 2000s, novel therapeutic approaches, including cellular therapies such as in vitro-expanded tumor-infiltrating lymphocytes (TIL) and anti-Claudin 18.2 CAR-T cells, have been investigated for advanced-stage patients.However, these strategies have largely failed to improve patient prognosis.Similar to most solid tumors, CAR-T cells in gastric cancer exhibit low persistence and peak expansion rates up to ten times lower than those observed in B-cell acute lymphoblastic leukemia (B-ALL).Recent studies have mapped the peritoneal carcinomatosis microenvironment, identifying potential targets to enhance cellular therapies.Objectives: This project aims to identify therapeutic targets in Brazilian patients and develop cellular therapy products from healthy donor lymphocytes or TIL from advanced-stage patients, capable of eliciting a robust and persistent antitumor response.Methodology: Patient samples will be analyzed via RNA sequencing (RNA-seq), and gene-editing techniques using CRISPR/Cas9 will be applied to disrupt PDCD1, HA VCR2, CTLA4, or LAG3 expression in anti-Claudin 18.2 CAR-T cells and anti-Claudin 18.2 TIL.Preliminary analyses in a cohort of 120 Brazilian patients revealed differentially expressed tumor microenvironment-related genes.Results: In primary gastric cancer lesions, CTLA4 and HA VCR2 exhibited significantly elevated expression compared to adjacent tissues.In peritoneal metastases, increased expression of CD274, LGAL9, and FGL1-encoding ligands for PD-1, TIM-3, and LAG-3-along with HA VCR2, was observed.Additionally, CLD18 isoform 2 predominated over isoform 1, highlighting its potential as an immunotherapy target. Conclusion:This project is expected to enhance cell resistance and expansion in the immunosuppressive tumor microenvironment, advancing cellular therapy strategies for gastric cancer.