Abstract 6142: Gain-of-function p53R172H mutation drives accumulation of neutrophils in the pancreatic tumor microenvironment promoting resistance to immunotherapy

Abstract

Abstract The immune microenvironment plays a critical role in cancer development, progression and resistance to therapy. Specific tumor genotypes can profoundly influence the composition of the immune microenvironment. After oncogenic KRAS, TP53 is the most frequently mutated gene in pancreatic ductal adenocarcinoma (PDAC). KRASG12D mutations in tumor cells are known to modify the immune landscape of PDAC, however the immune effects of neomorphic TP53 mutations have not been defined. Focusing on the most common neomorphic TP53 mutation in human PDAC, we sought to evaluate the non-cell-autonomous role of gain-of-function mutant Trp53R172H in modulating the immune microenvironment of pancreatic tumors by using KrasG12D-mutated mouse pancreatic ductal epithelial cells (PDEC) genetically engineered to express the Trp53R172H gain-of-function. Orthotopically implanted tumors derived from CRISPR-generated KrasG12D/+;Trp53R172H/+ PDEC had a distinct immune profile in comparison to KrasG12D/+;Trp53+/+ tumors, characterized by an influx of intratumoral CD11b+Ly6G+ neutrophils and concomitant decreases in CD3+ T cells, CD8+ T cells, and CD4+ T helper 1 (Th1) cells. Analysis of publicly available human PDAC cohorts revealed enrichment of genes in neutrophil-related pathways in TP53-mutated tumors. Knockdown of CXCL2, a neutrophil chemoattractant, in the tumor epithelial compartment of CRISPR KrasG12D/+;Trp53R172H/+ PDEC tumors reversed the neutrophil phenotype. Depleting neutrophils in mice bearing CRISPR KrasG12D/+;Trp53R172H/+ PDEC tumors augmented sensitivity to combined CD40 immunotherapy and chemotherapy. Collectively, these data link gain-of-function mutant Trp53R172H to the presence of intratumoral neutrophils in pancreatic cancer and suggests that tumor genotypes could inform patient selection for immunotherapy. Citation Format: Despina Siolas, Emily Vucic, Emma Kurz, Cristina Hajdu, Dafna Bar-Sagi. Gain-of-function p53R172H mutation drives accumulation of neutrophils in the pancreatic tumor microenvironment promoting resistance to immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6142.