Neoadjuvant Chemotherapy Is Associated with Altered Immune Cell Infiltration and an Anti-Tumorigenic Microenvironment in Resected Pancreatic Cancer

Abstract

Purpose: Neoadjuvant chemotherapy is increasingly administered to patients with resectable or borderline resectable pancreatic ductal adenocarcinoma (PDAC), yet its impact on the tumor immune microenvironment is incompletely understood. Experimental design: We employed quantitative, spatially-resolved multiplex immunofluorescence and digital image analysis to identify T-cell subpopulations, macrophage polarization states and myeloid cell subpopulations in a multi-institution cohort of up-front resected primary tumors (n=299) and in a comparative set of resected tumors after FOLFIRINOX-based neoadjuvant therapy (n=36) or up-front surgery (n=30). Multivariable-adjusted Cox proportional hazards models were used to evaluate associations between the immune microenvironment and patient outcomes. Results: In the multi-institutional resection cohort, immune cells exhibited substantial heterogeneity across patient tumors and were located predominantly in stromal regions. Unsupervised clustering using immune cell densities identified four main patterns of immune cell infiltration. One pattern, seen in 20% of tumors and characterized by abundant T cells (T cell-rich) and a paucity of immunosuppressive granulocytes and macrophages, was associated with improved patient survival. Neoadjuvant chemotherapy was associated with a higher CD8:CD4 ratio, greater M1:M2-polarized macrophage ratio, and reduced CD15+ARG1+ immunosuppressive granulocyte density. Within neoadjuvant-treated tumors, 64% showed a T-cell-rich pattern with low immunosuppressive granulocytes and macrophages. M1-polarized macrophages were located closer to tumor cells after neoadjuvant chemotherapy and colocalization of M1-polarized macrophages and tumor cells was associated with greater tumor pathologic response and improved patient survival. Conclusion: Neoadjuvant chemotherapy with FOLFIRINOX shifts the PDAC immune microenvironment towards an anti-tumorigenic state associated with improved patient survival.

Sequential pembrolizumab cooperates with platinum/5FU to remodel the tumor microenvironment in advanced gastric cancer: a phase II chemoimmunotherapy trial

“…Although our dataset lacks deep spatial characterization some of the broad features raised in our scRNAseq analyses are recapitulated in our multiplex IHC/IF analysis. To date some of the correlations between inferred network structure from scRNAseq and ground truth analysis such as IHC and IF and emerging spatial transcriptomics appear to largely hold, which is reassuring for our data 9,10,38,62,63,72,73 . As we needed to prioritize patient safety, our serial samples are limited to endoscopic biopsies of the primary tumor and we recognize the potential value for complementary spatial transcriptomics approaches.…”

Machine learning links T cell function and spatial localization to neoadjuvant immunotherapy and clinical outcome in pancreatic cancer

“…Additionally, our biological conclusions on impacts of αCD40 are concordant with several prior studies (8, 14, 72, 73, 77, 79, 80, 83), providing further support for our methods and findings. Future antibody panels may incorporate additional markers, such as chemokine receptors, to further characterize key T cell subsets, or additional cell lineage markers, such as myeloid cell markers (89), to further phenotype cell-cell interactions. It should be noted that in our study, treatment with αCD40 did not prolong DFS as compared to the treatment-naive cohort, and similar machine learning analyses on data from clinical trials that did improve outcome will be useful to validate our conclusions where the patient cohort size is better powered for survival analyses.…”

Reshaping the Pancreatic Cancer Microenvironment at Different Stages with Chemotherapy

“…Quantitatively, numerous studies demonstrated that neoadjuvant chemotherapy could elevate cytotoxic lymphatic cell (i.e., CD8+ T cells, conventional CD4+ T cells, and NK cells) and decline immunosuppressive myeloid cells (M2-skewed cells and myeloid-derived suppressor cells) infiltration, creating an anti-tumorigenic microenvironment [10,26,28,29] and a tendency to reverse natural tumor progression in pancreatic cancer.…”

“…Spatial distribution of cytotoxic CD8 T cells in proximity to cancer cells correlates with increased overall patient survival [31]. M1-polarized macrophages were located closer to tumor cells after neoadjuvant chemotherapy, and colocalization of M1-polarized macrophages and tumor cells was associated with greater tumor pathologic responses and improved patient survival [29]. Okubo et al [32] demonstrated that CD204+ macrophage levels in the cancer stroma were similarly independent of chemotherapy, whereas those in the cancer cell nests were lower in the treated group than in the naïve group.…”

“…Functionally, neoadjuvant chemotherapy induces proinflammatory cytokines and decreases pro-tumor cytokines from tumor-infiltrating T cells, with enhanced TNF-α and IL-2 and reduced IL-4 and IL-10 expression [10]. In addition, some immune subpopulations are repolarized anti-tumor ones with elevated M1/M2-skewed macrophages and conventional CD4+ T/Treg cells [29]. Immune cells in the chemotherapy arm, compared with the surgery arm, showed higher levels of the activated T-cell marker CD44 and lower levels of the immunosuppressive checkpoint molecule VISTA and TIGIT on CD8 T, Tregs, and exhausted CD4+ T cells [22,33].…”