Intratumoral injection of TLR9 agonist promotes an immunopermissive microenvironment transition and causes cooperative antitumor activity in combination with anti-PD1 in pancreatic cancer

Abstract

BackgroundComplex tumor and immune microenvironment render pancreatic ductal adenocarcinoma (PDAC) resistant to immune checkpoint inhibitors (ICIs). Therefore, a strategy to convert the immune hostile into an immunopermissive tumor is required. Recent studies showed that intratumoral injection of Toll-like receptor 9 agonist IMO-2125 primes the adaptive immune response. Phase I and II trials with intratumoral IMO-2125 demonstrated its safety and antitumoral activity.MethodsWe generated an array of preclinical models by orthotopically engrafting PDAC-derived cell lines in syngeneic mice and categorized them as high, low and no immunogenic potential, based on the ability of tumor to evoke T lymphocyte or NK cell response. To test the antitumor efficacy of IMO-2125 on locally treated and distant sites, we engrafted cancer cells on both flanks of syngeneic mice and treated them with intratumoral IMO-2125 or vehicle, alone or in combination with anti-PD1 ICI. Tumor tissues and systemic immunity were analyzed by transcriptomic, cytofluorimetric and immunohistochemistry analysis.ResultsWe demonstrated that intratumoral IMO-2125 as single agent triggers immune system response to kill local and distant tumors in a selected high immunogenic subtype affecting tumor growth and mice survival. Remarkably, intratumoral IMO-2125 in combination with systemic anti-PD1 causes a potent antitumor effect on primary injected and distant sites also in pancreatic cancer models with low immunogenic potential, preceded by a transition toward an immunopermissive microenvironment, with increase in tumor-infiltrating dendritic and T cells in tumor and lymph nodes.ConclusionWe demonstrated a potent antitumor activity of IMO-2125 and anti-PD1 combination in immunotherapy-resistant PDAC models through the modulation of immune microenvironment, providing the rationale to translate this strategy into a clinical setting.

Toll-like receptor 9 agonists and combination therapies: strategies to modulate the tumour immune microenvironment for systemic anti-tumour immunity

“…The combination of Vidutolimod (formerly CMP-001) and pembrolizumab (PD-1 Ab) entered Phase Ib clinical studies to cure patients with advanced melanoma, in which 25% of patients experienced tumour regression (including non-intratumoral injected tumours) [65]. The synergistic effect of TLR9 agonists cooperating with anti-PD-1 also has been validated in multiple mouse tumour models, including pancreatic ductal adenocarcinoma (PDAC) [66], lung cancer [67], breast cancer [68], colorectal cancer [69] and lymphoma [70]. In immunogenic B16/OVA melanoma, the combination of CpG1826 with anti-CTLA-4 resulted in bilateral tumour reduction, which was associated with increased tumour-antigen-specific T cell infiltration and decreased Tregs and inflammatory cytokines [71].…”

Understanding Tricky Cellular and Molecular Interactions in Pancreatic Tumor Microenvironment: New Food for Thought

“…Carbone et al. ( 185 ) showed that intratumoral injection of the Toll-like receptor 9 agonist IMO-2125 in combination with anti-PD1 activated an immune-suppressive to immune-permissive transition of the TME in PDAC models with both high and low immunogenic potential. Toll-like receptor 9 (TLR-9) is a pattern recognition receptor that is predominantly located in the cytoplasm of DCs, macrophages, NK cells, and other APCs.…”

Spatial transcriptomics identified mucin-specific O-glycosylation as a key pathway in pancreatic cancer development and a promising therapeutic target

“…Cells were daily inspected and routinely tested to be mycoplasma free by PCR assay. We characterized these models in a previous paper [34]( 10.1136/jitc-2021-002876) for both transcriptome and immune pro ling. From these cell lines we also established 3D cultures 13KC (DT4313), KPC06 (FC1242), KPC12 (FC1245).…”