Review Series
Abstract
Metabolic dysfunction–associated steatohepatitis (MASH) is a progressive form of liver disease characterized by hepatocyte injury, inflammation, and fibrosis. The transition from metabolic dysfunction–associated steatotic liver disease (MASLD) to MASH is driven by the accumulation of toxic lipid and metabolic intermediates resulting from increased hepatic uptake of fatty acids, elevated de novo lipogenesis, and impaired mitochondrial oxidation. These changes promote hepatocyte stress and cell death, activate macrophages, and induce a fibrogenic phenotype in hepatic stellate cells (HSCs). Key metabolites, including saturated fatty acids, free cholesterol, ceramides, lactate, and succinate, act as paracrine signals that reinforce inflammatory and fibrotic responses across multiple liver cell types. Crosstalk between hepatocytes, macrophages, and HSCs, along with spatial shifts in mitochondrial activity, creates a feed-forward cycle of immune activation and tissue remodeling. Systemic inputs, such as insulin-resistant adipose tissue and impaired clearance of dietary lipids and branched-chain amino acids, further contribute to liver injury. Together, these pathways establish a metabolically driven network linking nutrient excess to chronic liver inflammation and fibrosis. This Review outlines how coordinated disruptions in lipid metabolism and intercellular signaling drive MASH pathogenesis and provides a framework for understanding disease progression across tissue and cellular compartments.
Authors
Gregory R. Steinberg, Andre C. Carpentier, Dongdong Wang
Abstract
Metabolic dysfunction–associated steatotic liver disease (MASLD), now the most common cause of chronic liver disease, is estimated to affect around 30% of the global population. In MASLD, chronic liver injury can result in scarring or fibrosis, with the degree of fibrosis being the best-known predictor of adverse clinical outcomes. Hence, there is huge interest in developing new therapies to inhibit or reverse fibrosis in MASLD. However, this has been challenging to achieve, as the biology of fibrosis and candidate antifibrotic therapeutic targets have remained poorly described in patient samples. In recent years, the advent of single-cell and spatial omics approaches that can be applied to human samples have started to transform our understanding of fibrosis biology in MASLD. In this Review, we describe these technological advances and discuss the new insights such studies have provided, focusing on the role of epithelial cell plasticity, mesenchymal cell activation, scar-associated macrophage accumulation, and inflammatory cell stimulation as regulators of liver fibrosis. We also consider how omics techniques can enhance our understanding of evolving concepts in the field, such as hot versus cold fibrosis and the mechanisms of liver fibrosis regression. Finally, we touch on future developments and how they are likely to inform a more mechanistic understanding about how fibrosis might differ between patients and how this could influence optimal therapeutic approaches.
Authors
Fabio Colella, Neil C. Henderson, Prakash Ramachandran
Abstract
Inflammatory bowel diseases (IBDs) are complex immune disorders that arise at the intersection of genetic susceptibility, environmental exposures, and dysbiosis of the gut microbiota. Our understanding of the role of the microbiome in IBD has greatly expanded over the past few decades, although efforts to translate this knowledge into precision microbiome-based interventions for the prevention and management of disease have thus far met limited success. Here we survey and synthesize recent primary research in order to propose an updated conceptual framework for the role of the microbiome in IBD. We argue that accounting for gut microbiome context — elements such disease regionality, phase of disease, diet, medication use, and patient lifestyle — is essential for the development of a clear and mechanistic understanding of the microbiome’s contribution to pathogenesis or health. Armed with better mechanistic and contextual understanding, we will be better prepared to translate this knowledge into effective and precise strategies for microbiome restitution.
Authors
Megan S. Kennedy, Eugene B. Chang
Abstract
Pancreatic cancer has a 5-year survival rate of approximately 13% and is projected to become the second-leading cause of cancer-related deaths by 2040. Despite advances in preclinical research, clinical translation remains challenging, and combination chemotherapy remains the standard of care. The intrinsic heterogeneity of pancreas cancer underscores the potential of precision medicine approaches to improve patient outcomes. However, clinical implementation faces substantial challenges, including patient performance status, metastatic disease at diagnosis, intrinsic drug resistance, and a highly complex tumor microenvironment. Emerging targeted therapies, such as RAS inhibitors, offer promise for personalized treatment. These developments have prompted precision medicine–focused clinical trials using molecular subtyping for patient stratification. Effective development of precision medicine therapies depends heavily on robust preclinical models capable of accurately recapitulating the complexities of the pancreatic tumor microenvironment. Two-dimensional, air-liquid interface, and patient-derived organoid cultures combined with in vivo genetically engineered mouse models and patient-derived xenografts represent valuable experimental systems. This Review critically examines the strengths and limitations of these experimental model systems. We highlight their relevance and utility for advancing precision medicine strategies in pancreas cancer.
Authors
Vasiliki Pantazopoulou, Casie S. Kubota, Satoshi Ogawa, Kevin Christian Montecillo Gulay, Xiaoxue Lin, Hyemin Song, Jonathan R. Weitz, Hervé Tiriac, Andrew M. Lowy, Dannielle D. Engle
Abstract
The genetic landscape of pancreatic ductal adenocarcinoma (PDAC) is well-established and dominated by four key genetic driver mutations. Mutational activation of the KRAS oncogene is the initiating genetic event, followed by genetic loss of function of the CDKN2A, TP53, and SMAD4 tumor suppressor genes. Disappointingly, this information has not been leveraged to develop clinically effective targeted therapies for PDAC treatment, where current standards of care remain cocktails of conventional cytotoxic drugs. Nearly all (~95%) PDAC harbors KRAS mutations, and experimental studies have validated the essential role of KRAS mutation in PDAC tumorigenic and metastatic growth. Identified in 1982 as the first gene shown to be aberrantly activated in human cancer, KRAS has been the focus of intensive drug discovery efforts. Widely considered “undruggable,” KRAS has been the elephant in the room for PDAC treatment. This perception was shattered recently with the approval of two KRAS inhibitors for the treatment of KRASG12C-mutant lung and colorectal cancer, fueling hope that KRAS inhibitors will lead to a breakthrough in PDAC therapy. In this Review, we summarize the key role of aberrant KRAS signaling in the biology of pancreatic cancer; provide an overview of past, current, and emerging anti-KRAS treatment strategies; and discuss current challenges that limit the clinical efficacy of directly targeting KRAS for pancreatic cancer treatment.
Authors
Kristina Drizyte-Miller, Taiwo Talabi, Ashwin Somasundaram, Adrienne D. Cox, Channing J. Der
Abstract
Pancreatic ductal adenocarcinoma (PDAC) remains among the most lethal cancers, with metastasis as the primary driver of mortality. While metastatic mechanisms are shared across malignancies, PDAC metastasis poses unique therapeutic challenges due to the presence of extensive tumor heterogeneity, desmoplasia, and immunosuppression — features that enable diverse migratory behaviors and therapeutic resistance. Recent advances have shown that metastatic progression in PDAC emerges from dynamic interactions between tumor cell–intrinsic and microenvironmental factors, each adapting to evolving stressors throughout the metastatic cascade. In the primary tumor, genomic instability and epigenetic reprogramming generate subclones with heightened invasive potential, while dense stromal reactions and myeloid-dominated immune suppression facilitate escape. During circulation, PDAC cells employ distinctive survival strategies through homotypic clustering and heterotypic interactions with blood components. At distant sites, PDAC cells adapt to organ-specific microenvironments through context-dependent metabolic and immune modulation, resulting in phenotypes that diverge from the primary tumor. In this Review, we examine how tumor-stroma crosstalk mechanisms shape metastatic progression in PDAC, provide a framework for understanding why conventional therapies often fail against metastatic disease, and highlight emerging opportunities for stage- and site-specific therapeutic interventions that target these unique adaptations.
Authors
Ravikanth Maddipati
Abstract
Despite advances in multidisciplinary oncology care, curing patients diagnosed with pancreatic duct adenocarcinoma (PDAC) remains all too uncommon. In this Review, we discuss evolving concepts to guide the care of patients with operable PDAC, focusing on adjuvant and neoadjuvant systemic therapies, the ever-controversial topic of radiation therapy, and the emerging role of cancer vaccines. Given the promise of biomarkers to better predict therapeutic response, the development of KRAS inhibitors, our ability to deliver higher doses of radiation therapy more precisely and safely, and the technology to rapidly produce highly personalized cancer vaccines, there is reason to expect that the guidelines for the care of our patients with operable PDAC will change rapidly in the next few years.
Authors
John M. Bryant, Luis Ruffolo, Kevin Soares, Sarah Hoffe, Andrew M. Lowy
Abstract
The tumor microenvironment (TME) of pancreatic ductal adenocarcinoma (PDAC) is composed of a dense stromal compartment and is poorly vascularized, resulting in limited nutrient delivery. As a result, PDAC cells must adapt to cope with the metabolic stresses brought on by TME nutrient limitation. In this article, we first review recent studies that have provided quantitative measurements of nutrient levels in the PDAC TME. These studies have provided a new understanding of the nutrient limitations and metabolic stresses that occur in PDAC. We next discuss the adaptive strategies employed by PDAC in response to TME nutrient limitation. We propose that PDAC adaptations to metabolic stress can be generalized into four categories: (a) cutting down on metabolic costs by recycling metabolites and suppressing nonessential processes, (b) upregulating biosynthetic pathways to meet TME metabolic demands, (c) supporting essential metabolic processes with alternative fuel sources, and (d) dampening antiproliferative and cell death responses that nutrient limitation normally triggers. Improving our understanding of the nutrient limitations within the TME, and the adaptations cells employ to cope with these stresses, provides a more complete picture of PDAC biology and reveals new opportunities for therapeutic targeting of this disease.
Authors
Colin Sheehan, Alexander Muir
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is known to progress from one of two main precursor lesions: pancreatic intraepithelial neoplasia (PanIN) or intraductal papillary mucinous neoplasm (IPMN). The poor survival rates for patients with PDAC, even those diagnosed with localized disease, highlight the need for pancreatic cancer interception at the precursor stage. Although their basic biological drivers are well characterized, practical strategies for PanIN and IPMN interception remain elusive due to difficulties with detection, risk stratification, and low-morbidity intervention. Recently, advances in liquid biopsy, spatial multiomics analysis, and machine learning technology have provided deeper understanding of the molecular landscapes underlying pancreatic precursor development and progression. In this Review, we outline the different histologic phenotypes, clinical characteristics, and neoplastic cell–intrinsic and –extrinsic drivers of PanINs and IPMNs, with particular focus on current and potential future opportunities for pancreatic precancer interception.
Authors
Brian A. Pedro, Laura D. Wood
Abstract
Metabolic dysfunction–associated steatotic liver disease (MASLD) is the most common pediatric liver disease, affecting approximately 10% of children. Its prevalence is rising at an alarming rate, with cases increasingly identified even in early childhood. While MASLD shares key features across the lifespan, its earlier onset reflects developmental vulnerabilities and unique mechanistic drivers. Perinatal influences, including maternal obesity, gestational diabetes, and early-life nutritional exposures, play a central role by disrupting metabolic programming, driving mitochondrial dysfunction, and inducing epigenetic modifications. These early stressors interact with genetic predispositions, such as PNPLA3 and TM6SF2 variants, to amplify susceptibility and shape disease severity. Pediatric MASLD also exhibits distinct histological features, particularly predominant periportal (zone 1) steatosis, inflammation, and fibrosis, which contrast with the centrilobular or pericentral (zone 3) patterns often seen in adults. These findings provide insight into spatial heterogeneity, developmental pathophysiology, and unique disease progression trajectories in children. Addressing MASLD in children requires pediatric-specific approaches to diagnosis, risk stratification, and intervention. By integrating epidemiological trends, mechanistic insights, and translational advances, this Review highlights opportunities for targeted therapies and prevention strategies aimed at mitigating early-life drivers of MASLD, reducing disease burden, and improving long-term outcomes.
Authors
Jeffrey B. Schwimmer, Sudha B. Biddinger, Samar H. Ibrahim
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