Abstract C055: The IL1RAP-blocking antibody nadunolimab disrupts pancreatic cancer cell and fibroblast crosstalk, reduces recruitment of myeloid cells and inhibits tumor growth

Abstract IL1RAP is expressed by tumor and stromal cells in pancreatic ductal adenocarcinoma (PDAC). Signaling by IL1 through the IL1R1/IL1RAP complex promotes cancer progression and contributes to the immune suppressive microenvironment in PDAC. The IL1RAP-blocking antibody nadunolimab blocks the signaling of both IL-1a and IL-1b and is currently evaluated in a phase I/IIa clinical study for PDAC (NCT03267316). Cancer-associated fibroblasts (CAFs) are a primary constituent of the PDAC stroma and has previously been shown to be regulated by IL-1. The aim of this study was to explore the functional consequences of nadunolimab treatment on the crosstalk between tumor cells and CAFs. Co-cultures of the PDAC cell line BxPC3 and pancreatic CAFs induced major changes in gene expression of both cell types as determined by RNA sequencing, indicating an extensive communication between the two cell types. Inclusion of nadunolimab to the co-cultures resulted in only 6 differentially expressed genes (padj<0.05) in the BxPC3 cells but 294 differentially expressed genes (padj<0.05) in CAFs compared to an isotype control antibody. Among the nadunolimab-downregulated genes were several cytokines, including CXCL1, CXCL2, CXCL3, CXCL6, IL8 and CCL2 (padj<0.05). Hence, we next measured cytokine concentrations in the co-culture medium and confirmed that nadunolimab treatment resulted in significant reductions of CXCL1, LIF, IL8 and CSF3 (p<0.05). We also found reduced levels of CCL2 (p=0.059). To identify which biological processes were affected by nadunolimab, we performed gene set enrichment analysis (GSEA). Nadunolimab induced a gene expression signature in the CAFs with negative enrichments of mononuclear cell migration (padj 0.003) and monocyte chemotaxis (padj 0.003). In line with these findings, conditioned media from co-cultures treated with nadunolimab exhibited reduced capacity to stimulate migration of peripheral blood monocytes in transwell assays (p=0.033). Interestingly, blockade of IL1b only using a neutralizing anti-IL1b antibody did not affect cell migration, suggesting that the broader blockage of cytokine signaling by nadunolimab was required to reduce monocyte migration. To assess whether the effects of IL1RAP-blockade by nadunolimab on PDAC-CAF crosstalk is relevant for tumor growth in vivo, PDAC cells and fibroblasts or PDAC cells alone were subcutaneously inoculated in Balb/c nude mice. Notably, treatment with nadunolimab reduced tumor growth in mice transplanted with a mixture of BxPC3 and CAFs (N=10 and N=8, p=0.035) but not in mice transplanted with BxPC3 cells only. This study demonstrates that antibody-based blockade of IL1RAP by nadunolimab disrupts interactions between PDAC cells and CAFs resulting in substantial global transcription changes in the CAFs, reduced recruitment of monocytes and decreased PDAC tumor growth in vivo. These findings suggest that targeting IL1RAP has a major impact on the PDAC tumor microenvironment and reveals new anti-tumor mechanisms of nadunolimab treatment. Citation Format: Nils Hansen, Pablo Peña, Finja Hansen, Petter Skoog, Susanne Larsson Faria, Karin von Wachenfeldt, Carl Högberg, Camilla Rydberg Millrud, David Liberg, Marcus Järås. The IL1RAP-blocking antibody nadunolimab disrupts pancreatic cancer cell and fibroblast crosstalk, reduces recruitment of myeloid cells and inhibits tumor growth [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C055.