Abstract PO-020: Heating up immune cold pancreatic adenocarcinoma with bioengineered immunotherapy remodels tumor microenvironment and prevents metastasis in vivo
Authors: Ragulan Chanthirika , Lawrence Patrick Varun , Ps Hari , Desai Krisha , Ishihara Jun , Sadanandam Anguraj 
Published: November 2021

Abstract
Background: Immunotherapy has resulted in a paradigm shift in the treatment of multiple solid tumors. Still, immunotherapy in unselected pancreatic ductal adenocarcinoma (PDAC) patients has been disappointing. This failure is likely multifactorial and associated with a high immunosuppressive and desmoplastic tumor microenvironment (TME). This unique TME in PDAC leads to various immune escape mechanisms employed by the tumor. While this could be overcome by therapy involving IL12 (or other cytokines) alone, they often fail due to immune-related adverse effects (irAEs). On the other hand, bioengineered collagen-binding domain-linked IL-12 (CBD-IL12; T- cell stimulant that delivers IL12 to collagen-rich regions) is effective in other cancers in pre-clinical settings. Here, we hypothesise that different immune (cold/hot) and collagen content in mice determines their treatment efficacy and irAEs to CBD-IL12 or combination immunotherapy. Methods: Three (7947, 7784 and 2334) out of 12 syngeneic orthotopic models of PDAC were classified into immune “hot” (immunehot) or “cold” (immunecold) with varying collagen levels (collagenhigh or collagenlow) using cross-species statistical inference (in silico analysis). Mice were treated with vehicle or two bioengineered treatment arms – CBD-IL-12 or CBD-IL-12 + anti-PD1. Tumor growth and metastasis was assessed in an interventional trial. Transcriptome profiling was performed on harvested tumors. Results: As predicted by in silico analyses, our in vivo experiments confirmed 7947 syngeneic model as immune cold (immunecold) and resistant to selected stimulatory (GITR) and inhibitory (anti-PD1 or anti-CSF1R+anti-PD1) immunotherapies. To improve the immunotherapy in this immunecold model, we utilised the opportunity that this model has increased collagen (collagenhigh), hence, treating them with CBD-IL12 or combination with anti-PD1 therapy may provide improved treatment efficacy and reduce irAEs. Remarkably, the treatments prevented distant metastasis to the liver by significantly reducing tumor burden (p&lt;0.05) and toxicity. The mechanistic analysis demonstrated a cascade of TME changes, including increased CD8 T cells and MHCII+ myeloid cell-based antigen presentation in the treated tumors compared to the control. This increased antigen presentation was associated with macrophage repolarisation from M2 to M1. This was not the case in two other immunecold/collagenlow or immunehot/collagenhigh models. Conclusion: Our integrated strategy to pre-select mouse models based on their TME (immune/collagen) profiles improves personalised bioengineered immunotherapy response in immune cold PDAC. Furthermore, the added benefit of preventing metastasis is rather promising and warrants further investigation in aggressive disease like PDAC.
Citation Format: Chanthirika Ragulan, Patrick Varun Lawrence, Hari Ps, Krisha Desai, Jun Ishihara, Anguraj Sadanandam. Heating up immune cold pancreatic adenocarcinoma with bioengineered immunotherapy remodels tumor microenvironment and prevents metastasis in vivo [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PO-020.