Abstract 6575: Selective targeting of integrins αVβ8 and αVβ1 within the dynamic ecosystem of pancreatic cancer to improve the overall anti-tumor response

Abstract Pancreatic ductal adenocarcinoma (PDA) has a 5-year survival of less than 10% and remains the 3rd leading cause of cancer-related death in Western societies. New treatment options are urgently needed. TGF-β promotes stromal cell reprogramming, immunosuppression, and fibrinogenesis in cancers, including PDA. Integrins αVβ8 and αVβ1 are important activators of TGF-β signalling. Selective integrin blockade has recently emerged as a promising therapeutic approach to address TGF-β-mediated immunotherapy resistance and improve anti-tumour response across cancer models. The purpose of this study was to assess the in vivo efficacy of small molecule inhibitor PLN-104, a selective inhibitor of αVβ1, and PLN-101095, a dual inhibitor of αVβ8 and αVβ1, in well-annotated models of advanced PDA. We determined the preclinical efficacy and detailed anti-stromal effect of PLN-101095 inhibitor in genetically defined and patient-derived PDA models, including clinically relevant combinations with standard of care (SoC) chemotherapy and anti-programmed death receptor-1 antibody (anti-mPD-1). Mechanistic assessment of alterations in tumour cell-stromal cell crosstalk was performed using comprehensive transcriptomics and immunofluorescence approaches. Dual targeting of αVβ8 and αVβ1 with PLN-101095 in the syngeneic LSL-KrasG12D/+;LSL-Trp53R172H/+;Pdx1-Cre (KPC) model effectively reduced tumour growth by 45% in comparison to the vehicle, and significantly delayed disease progression in vivo. Single-cell analysis of PLN-101095-treated KPC pancreatic tumours revealed a positive reprogramming of malignant cells from a mesenchymal to a more epithelial-like state. This effect was further associated with an upregulation of MHC type I/II markers and corresponding downregulation of pro-metastatic factors across diverse cancer sub-populations. Additionally, combining PLN-101095 with anti-mPD-1 antibody further improved survival in this aggressive model of metastatic PDA. In a second syngeneic model, Pan02, PLN-101095 in combination with anti-mPD-1 antibody significantly reduced tumour growth, while increasing CD8+ lymphocyte infiltration. The combination of PLN-101095 with Anti-PD1 increased MHC and IFN gene expression. Finally, utilizing patient-derived models of metastatic PDA revealed that both PLN-104 and PLN-101095 significantly blocked tumour growth, improved the response to SoC chemotherapy Gemcitabine/Abraxane, and reduced metastatic spread to distant sites. In conclusion, these data provide scientific rationale for the design of future PLN-101095 and SoC chemotherapy as well as immunotherapy combinations in pancreatic cancer, with Phase I first-in-human oncology studies with PLN-101095 plus ICB already underway. Citation Format: Dannielle Upton, Diego Chacon Fajardo, Sofia Omari, Sean Porazinski, Benjamin McLean, Diana Schuhmacher, Aji Istadi, Australian Pancreatic Cancer Genome Initiative, Vishal Kothari, Darren Finkelstein, Tim Machajewski, Fernando Rock, Scott Turner, Marina Pajic. Selective targeting of integrins αVβ8 and αVβ1 within the dynamic ecosystem of pancreatic cancer to improve the overall anti-tumor response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6575.