Abstract C014: CXCR4 inhibition enhances anti-tumor immune response in an ex vivo autologous patient-derived organoids and PBMC model system of pancreatic ductal adenocarcinoma
Authors: Pellicciotta Ilenia 
Published: January 2024

Abstract
Introduction Immune checkpoint blockade either alone or in combination with chemotherapy has been ineffective in pancreatic ductal adenocarcinoma (PDAC) likely due to underlying immunosuppressive pathways. The CXC chemokine receptor type 4 (CXCR4)/chemokine (CXC motif) ligand 12 (CXCL12) axis is one key immunosuppressive pathway. CXCL12 (released by cancer-associated fibroblasts (CAF)) binds to CXCR4 on CD8+ T cells (CTL) and decreases its infiltration into the tumor. Encouraging preclinical studies from murine PDAC models and human PDAC tumor sections have demonstrated infiltration of T cells with tumors after co-inhibition of CXCR4 and PD1/PDL1, however with limited tumor regressions in mouse model. We established an innovative ex vivo autologous patient-derived immune/organoid (PDIO) co-culture system that allows studying the interactions between distinct immune cells and tumor cells. Methods Patient-derived tumor organoids (PDTOs) generated from tumors resected from patients diagnosed with pancreas cancer were grown to confluence in Matrigel domes. We conducted ex vivo migration assays with autologous peripheral blood mononuclear cells (PBMCs) which were placed in the surrounding liquid phase of the matrigels. We separately treated PBMCs and PDTOs with AMD3100, an inhibitor of CXCR4, and tested the role of CXCR4 inhibition on PBMCs and PDTOs in T cell exclusion and immune cell activation. Results Pre-treatment of PBMCs with AMD3100 increased CD8+ T cell mobilization towards autologous PDTOs in matrigel dome migration assays by up to 11-fold. After co-culture in the liquid interphase of PDTOs matrigel domes, AMD3100 pre-treated PBMCs exhibit a more robust proliferative response compared to untreated PBMCs and a significant increase in the number of reactive T cells migrated inside the PDTO matrigel dome and expressing activation markers (p=0.02). Nearly 50% of T cells in proximity of tumor cells produce the cytotoxic factor Granzyme B (p=0.002), with AMD3100 treatment of PBMC increasing it by up to 3-fold compared to untreated PBMC. CXCR4 inhibition of PDTOs resulted in modulation of immune checkpoint ligands involved in the tumor immune response and tumor cell immunogenicity. Combination treatment of PBMCs and PDTOs with AMD3100 and anti-PD1 antibody ultimately resulted in increased tumor cell death with up to 45% of PDTOs exhibiting apoptosis markers after coculture with AMD3100-treated PBMC, implicating a role of this combination in the clinic. Conclusions We demonstrate that inhibition of CXCR4, not only increases migration of autologous T cells towards PDTOs, but also results in proliferation of PBMCs and activation of T cells. Furthermore, CXCR4 inhibition of PDTOs increases antigen presentation and tumor cell death. Inhibition of CXCR4 is an attractive therapeutic target as it enhances anti-tumor immune response via dual targeting of immune and neoplastic compartments. We are testing this combination in a multicenter investigator-initiated clinical trial in treatment-naïve metastatic PDAC patients.
Citation Format: Ilenia Pellicciotta. CXCR4 inhibition enhances anti-tumor immune response in an ex vivo autologous patient-derived organoids and PBMC model system of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C014.