Expressing CXCR4 in CAR-T cells Suppresses MDSCs Recruitment via STAT3/NF-κB/SDF-1α axis to enhance Anti-tumor Efficacy against Pancreatic Cancer.

Claudin18.2 (CLDN18.2)-specific chimeric antigen receptor (CAR-T) cells displayed limited efficacy in CLDN18.2 positive pancreatic ductal adenocarcinoma (PDAC). Strategies are needed to improve the trafficking capacity of CLDN18.2-specific CAR-T cells. PDAC has a unique microenvironment that consists of abundant cancer- associated fibroblasts (CAFs), which could secrete stromal cell-derived factor 1α (SDF-1α), the ligand of CXCR4. Then we constructed and explored CLDN18.2-targeted CAR-T cells with CXCR4 co-expression in treating immunocompetent mouse models of PDAC. The results indicated that CXCR4 could promote the infiltration of CAR-T cells and enhance their efficacy in vivo. Mechanistically, the activation of signal transducer and activator of transcription 3(STAT3) signaling was impaired in CXCR4 CAR-T cells, thereof reduced the release of inflammatory factors, such as TNF-α, IL-6 and IL-17A. Then, the less release of inflammatory factors suppressed SDF-1α secretion in CAFs via NF-κB pathway. Therefore, the decreased secretion of SDF-1α in feedback decreased the migration of myeloid-derived suppressor cells (MDSCs) in tumor sites. Overall, our study demonstrated that CXCR4 CAR-T cells could traffic more into tumor sites and meanwhile suppress MDSCs migration via STAT3/NF-κB/SDF-1α axis, to obtained better efficacy in CLDN18.2 positive pancreatic cancer. Our findings provide a theoretical rationale for CXCR4 CAR-T cell therapy in PDAC.