Cancer-associated fibroblasts (CAFs) form a dynamic ecosystem that critically influences tumor progression and therapeutic response. Although recent advances in single-cell and spatial omics have uncovered profound stromal diversity, interpreting the mechanistic relevance of this complexity remains a challenge. Here, we propose a more unifying conceptual framework to bridge high-dimensional data with experimental biology. By categorizing CAFs into conserved molecular phenotypes and distinct spatial archetypes, this model illustrates how CAF identities are intimately linked to local tissue contexts. This refined framework brings the complexity of the tumor stroma into greater focus, underscoring the necessary transition from broad stromal targeting toward precision, context-specific modulation. Ultimately, we hope this integrated effort will aid in the collaborative development of next-generation therapies that selectively target pathogenic stroma in cancer to improve patient outcomes.

Pancreatic ductal adenocarcinoma remains one of the deadliest malignancies, characterized by late diagnosis, aggressive biology and limited therapeutic success. Advances in multiagent chemotherapy have improved outcomes across disease stages, whereas precision medicine approaches are reshaping treatment paradigms. Personalized RNA vaccines and oncogenic KRAS-directed agents represent emerging immunological and molecular frontiers. Multimodal treatment regimens and surgical innovations, including vessel-oriented and minimally invasive techniques, have enhanced complete resection rates and enabled conversion of initially unresectable locally advanced pancreatic cancer into resectable disease. Increasingly, multidisciplinary, biology-guided strategies define resectability and the sequence of systemic and local therapies. The tumour microenvironment’s complex stromal and immune ecology remains central to therapeutic resistance but also offers opportunities for rational combination therapy. Early detection and risk-adapted surveillance for high-risk individuals are advancing, as are artificial intelligence-assisted imaging and liquid biopsy approaches. Despite persistent challenges, the convergence of mechanistic insights, precision therapeutics and supportive care provides a framework for transforming pancreatic ductal adenocarcinoma from an inevitably lethal disease towards a better manageable condition. In this Primer, Roth et al. discuss the epidemiology, current knowledge of pathophysiology, diagnosis, management and quality of life of individuals with pancreatic ductal adenocarcinoma, which remains one of the deadliest malignancies globally.

Abstract Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest cancers, with limited treatment options and poor survival rates. It is characterised by strong driver mutations, epigenetic reprogramming, and a dense tumour microenvironment (TME). A defining feature of the PDAC TME is its fibrotic stroma, which is largely composed of cancer-associated fibroblasts (CAFs). Distinct CAF populations have been implicated in PDAC progression, but the mechanisms that govern their crosstalk with the cancer cells are poorly understood. We generated genetically engineered pancreatic stellate cells (PSCs) modelling interleukin-1 (IL-1)-dependent inflammatory CAFs (iCAFs) and transforming growth factor-β (TGF-β)-dependent myofibroblastic CAFs (myCAFs) to investigate how distinct stromal populations shape the epigenetic landscape of pancreatic ductal adenocarcinoma (PDAC). We found that iCAFs, but not myCAFs, promoted gemcitabine resistance in epithelial tumour cells and identified STAT1 as a critical mediator of iCAF–tumour cell crosstalk. Mechanistically, STAT1 drove the induction of interferon (IFN)-responsive genes, while blockade of IFN-β attenuated iCAF-mediated transcriptional reprogramming. Genetic ablation of STAT1 in tumour cells abolished iCAF-induced chemoresistance and associated transcriptional changes. In an orthotopic in vivo model, STAT1 knockout significantly prolonged survival following gemcitabine treatment, supporting a central role for STAT1 signalling in stromal-driven therapy resistance. We provide a comprehensive analysis on how IL-1-dependent iCAFs contribute to epigenetic reprogramming in PDAC and uncover a previously undescribed role for STAT1 in stromal-epithelial interactions. These findings reveal distinct, non-overlapping mechanisms by which CAF subtypes modulate tumour behaviour and identify STAT1 as a therapeutic vulnerability that can be exploited to sensitise PDAC to standard chemotherapy. Significance statement This study establishes that the epigenetic landscape of PDAC is differentially shaped by iCAF- and myCAF-like PSCs and defines STAT1 as a mediator of iCAF-induced chemoresistance and transcriptional reprogramming. We demonstrate that genetic ablation of STAT1 sensitises tumours to gemcitabine in vivo , extending survival and positioning STAT1 as an actionable target to overcome stromal-mediated therapy resistance in PDAC.

Abstract Perturbation of cell polarity is a hallmark of pancreatic ductal adenocarcinoma (PDAC) progression. Scribble (SCRIB) is a well-characterized polarity regulator that has diverse roles in the pathogenesis of human neoplasms. To investigate the impact of SCRIB deficiency in PDAC development and progression, Scrib expression was genetically ablated in well-established mouse models of PDAC. Scrib loss in combination with KrasG12D did not influence development of pancreatic intraepithelial neoplasms in mice. However, Scrib deletion cooperated with KrasG12D and concomitant Trp53 heterozygous deletion to promote invasive PDAC and metastatic dissemination, leading to reduced overall survival. Immunohistochemical and transcriptome analyses revealed that Scrib-null tumors display a pronounced reduction of collagen content and an abundance of cancer-associated fibroblasts (CAF). Mechanistically, IL1α levels were reduced in Scrib-deficient tumors, and Scrib knockdown downregulated IL1α in mouse PDAC organoids (mPDO), which impaired CAF activation. Furthermore, Scrib loss increased YAP activation in mPDOs and established PDAC cell lines, enhancing cell survival. Clinically, SCRIB expression was decreased in human PDAC, and SCRIB mislocalization was associated with poorer patient outcome. These results indicate that SCRIB deficiency enhances cancer cell survival and remodels the tumor microenvironment to accelerate PDAC development and progression, establishing the tumor suppressor function of SCRIB in advanced pancreatic cancer. Significance: SCRIB loss promotes invasive pancreatic cancer development via both cell-autonomous and non–cell-autonomous processes and is associated with poorer outcomes, denoting SCRIB as a tumor suppressor and potential biomarker for the prediction of recurrence.

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis and is characterised by an extensive pro-tumorigenic stroma. Although most PDAC cases occur in older patients, the impact of ageing on malignant-stromal interactions and therapy response remains poorly understood. Here, we established orthotopically-grafted organoid-derived PDAC models across three murine age groups to characterise changes in the PDAC stroma and malignant cells with ageing. Cross-species analyses of tumour transcriptomes using a graph-embedding approach showed that integrating mouse models of different ages better captures the diversity of human PDAC, and that aged models more faithfully recapitulate the biology of older patients with PDAC. We also demonstrated that aged PDAC models have a more inflammatory stroma than that of younger tumours, shaping the malignant cell transcriptome. Finally, graph-embedding identified IRAK4 as a candidate therapeutic vulnerability in aged, but not young, KRAS- and p53-mutant PDAC, which we validated in preclinical drug studies. These findings highlight how ageing is a critical determinant of PDAC biology and associated therapeutic vulnerabilities, which should be an important consideration when designing disease models for preclinical development of precision therapies. ### Competing Interest Statement The authors have declared no competing interest. Cancer Research UK UK Research and Innovation Pancreatic Cancer Research Fund, https://ror.org/04ef2za66 United States Department of Defense, https://ror.org/0447fe631 Pancreatic Cancer UK, https://ror.org/04ad7pn51 Royal Society, https://ror.org/03wnrjx87

Pancreatic ductal adenocarcinoma (PDAC) has an extremely poor survival rate. This is largely due to patients being diagnosed when the disease has already metastasized to other organs, most commonly the liver and lungs. For these patients, no effective treatment exists, and the 5-year survival rate is less than 5%. Despite its highly metastatic nature, the timing and mechanisms of metastasis formation in PDAC remain largely unknown. In this issue of Cancer Research, Lasse Opsahl and colleagues identify a role for premalignant pancreatic intraepithelial neoplasia (PanIN) lesions in lung premetastatic niche formation. By performing histology and single-cell RNA sequencing analyses of a KRASG12D inducible mouse model of PDAC, the authors identify pSTAT3+ fibroblasts in the lungs, but not the liver, upon PanIN formation. Notably, pSTAT3+ fibroblasts in the lungs are required for metastasis formation. Mechanistically, KRAS activation in the pancreatic epithelium and consequential IL6 release activate STAT3 in lung fibroblasts. Altogether, Lasse Opsahl and colleagues demonstrate that PanIN lesions prime the lungs to favor future malignant cell outgrowth before the development of a pancreatic tumor and that blocking the formation of this lung premetastatic niche impairs metastasis in mice. See related article by Lasse Opsahl et al., p. 22