Targeting progression of liver damage in NASH
Overview
Non-alcoholic steatohepatitis, or NASH, is a liver disease in which a build-up of fat in the liver is followed by inflammation and cell damage.1 It is rapidly becoming a leading cause of chronic liver disease2 and a reason for liver transplantation.3 People with NASH are also at greater risk of type 2 diabetes and cardiovascular disease.4
Through our metabolic research programmes, we are developing promising approaches for reducing liver fat and inflammation, with the ambition of halting or reversing progression of fibrosis and irreversible liver damage. Such advances also have implications for alleviating type 2 diabetes, as well as cardiovascular and renal diseases, since emerging science suggests significant ‘cross-talk’ between the liver and other organs.
At the forefront of precision medicine research, we are targeting genetic mutations associated with NASH, which are responsible for an approximately four-fold increase in risk of the disease.5 By silencing these mutations, our goal is to interrupt key NASH mechanisms.
Through our investment in a cell therapy department and commitment to studying the mechanisms of regeneration, we are exploring the potential of replacing diseased liver tissue with the aim of restoring liver health.
By targeting multiple mechanisms, we are developing a combination approach to the treatment of NASH and associated cardiovascular and renal diseases with the bold ambition of reversing the current upward trends in morbidity and mortality.
Non-alcoholic fatty liver disease (NAFLD) is the most rapidly increasing cause of liver morbidity and mortality.2
People with the progressive form of NAFLD, non-alcoholic steatohepatitis (NASH), have marked fat accumulation in liver cells (steatosis), dead and dying liver cells (ballooning and degeneration) and liver inflammation. This can progress to fibrosis, cirrhosis and liver cancer. People with NASH are also at increased risk of cardiovascular disease and diabetes.4
Due to genetic factors, some people are at higher risk of developing NASH, and the PNPLA3 gene is currently a promising target for therapy.4,6,7
For people with NASH, treatment options are limited and largely based on diet and lifestyle changes.4
NASH is therefore an essential part of AstraZeneca’s Cardiovascular, Renal & Metabolism (CVRM) research. The liver and other major organs share disease mechanisms arising from impaired glucose and fat metabolism8 that are relevant across our CVRM programmes.
Internally and in collaboration with external world-leading researchers, we are investigating drug targets and potential medicines for the metabolic and genetic components of NASH, as well as the wider implications for treatment of patients with cardiovascular and renal disease.
Through our early-stage tissue regeneration programme, we are also investigating opportunities for restoring liver health in people with NASH.
Towards our goal of developing novel therapies for NASH, we are using a holistic approach that takes account of what happens not only in a patient’s liver but in their heart and kidneys.
In its early stages, NASH may be largely silent, with patients unaware they have the disease.
Abnormal blood test results including raised levels of liver enzymes may suggest NASH, and ultrasound or MRI scans can show fat in the liver and liver stiffness. However, only a liver biopsy can show inflammation, severity of fibrosis and other signs of liver damage, and confirm a diagnosis of NASH.4
We are actively engaged in two major public-private partnership consortia that are testing non-invasive tools for NASH diagnosis that may in the future be used as endpoints in clinical trials of potential new medicines. Through our leadership role in the US-based NIMBLE consortium, we are working towards enhancing the quality of our NASH clinical trials, all of which include in-depth analysis of soluble and imaging biomarkers for NASH diagnosis. In the LITMUS consortium in Europe, there is a major focus on development of pre-clinical models and patient-reported outcome tools for NASH with the aim of using them in future studies.
The growing recognition of NASH as a major global health problem has meant there is an urgent need for simple, non-invasive ways to diagnose the disease and to monitor response to the potential treatments for NASH that are in development.
In further collaborations, for example in Sweden, we are testing novel biomarkers in cohorts of patients who are being followed up for long periods of time. We are also collaborating in the GOLDMINE study which is aiming to recruit 1,000 patients to evaluate the usefulness of non-invasive imaging biomarkers in prediction of disease progression and clinical outcomes in NAFLD.
Together, these collaborations hold substantial promise for delivering viable, non-invasive tools as an alternative to invasive biopsy, with potential benefits for patients both in routine care and as participants in clinical trials for NASH drug development.
Through our own research and as active participants in major international collaborations and consortia, we are committed to the development of tools for non-invasive diagnosis and monitoring of patients with NASH with the aim of providing the most appropriate targeted therapy.
Having recognised the importance of targeting the same disease drivers that occur in the liver and other organs, we are focusing on agents to systematically improve metabolic function. In patients with NASH, many of whom also have type 2 diabetes and obesity, the aim is to enhance glucose control, reduce lipid production and induce weight loss while improving liver health.
A promising potential medicine in development at AstraZeneca is a dual agonist of the glucagon-like protein-1 and glucagon receptors (GLP-1R/GcgR).10 This is designed to improve metabolic function by working like the intestinal hormone, oxyntomodulin, which is known to decrease food intake and increase energy expenditure, leading to weight loss in overweight and obese individuals.10
GLP-1 receptors are found mainly in the brain and pancreas, and activation results in beneficial effects on food intake, insulin secretion and weight loss.11 Glucagon receptors are found in the liver where activation results in increased energy expenditure and reduced lipid production.12
Newly published research in Nature Metabolism showed that our candidate dual GLP-1R/GcgR agonist has beneficial effects in preclinical NASH models.12 In these models of disease, it reduced steatosis and inflammation, reversed fibrosis, improved glucose control, decreased food intake and induced weight loss. Underpinning these benefits were suppression of lipid production in the liver and improved mitochondrial activity, indicative of enhanced metabolic function.
Clinical studies are now underway to investigate the treatment effects on liver function, glucose levels and weight loss in patients with NASH.
When we tested our dual GLP-1/glucagon receptor agonist preclinically in a NASH model, we were expecting to see a reduction in steatosis but were thrilled by the magnitude of the reductions in inflammation and fibrosis that were achieved and could be attributed to the glucagon component.
The discovery that a dual GLP-1 and glucagon receptor agonist can reverse fibrosis in a preclinical NASH model is a major achievement. This research was a massive team effort, requiring state-of-the-art technologies and a wide range of research expertise.
It takes just a single nucleotide substitution in the PNPLA3 gene to severely impair normal fat breakdown in liver cells.6 As a result of the mutation, called PNPLA3 I148M, a dysfunctional liver enzyme is produced that is not only unable to digest fat itself, but impedes another type of enzyme from doing it too.6 Fat accumulates in liver hepatocytes with toxic effects including the inflammation and fibrosis seen in NASH.6
Through a collaboration with the biotech company Ionis, and working closely with Professor Stefano Romeo from the University of Gothenburg, Sweden – a world leader investigating the role of genetic variants in modulating metabolic liver disease, we are investigating advanced ligand conjugated antisense oligonucleotides (ASOs) to ‘silence’ PNPLA3 with the aim of restoring fat break down in the liver.7
In preclinical research, ASO treatment reduced liver steatosis, inflammation and fibrosis in a NAFLD model.7 In a further study, ASO-mediated silencing of PNPLA3 was shown to reduce intracellular lipid levels in human liver cells. As a result of these promising preclinical results, early phase clinical research is underway.
Alongside our PNPLA3 research, we are collaborating with Professor Romeo in developing ‘miniature livers’, for use in laboratory research, to help us understand more about the biology of PNPLA3 mutations and other genetic variants in relation to the early stages of fibrosis induced by lipid accumulation in NASH.13,14 Optimising the conditions for growth and scale up of these 3D spherical clusters of human liver cells has been an important achievement, with the resulting models also being used to identify novel compounds for screening as potential new medicines.
With our preclinical studies, we have verified the therapeutic potential of inhibiting the effects of a strong genetic driver identified in NASH, the PNPLA3 mutation in the liver. This points towards the possibility of a therapeutic effect in patients with NASH carrying the PNPLA3 mutation which we are starting to investigate.
Watch this NASH animation
No solid organ of the body has the capacity to regenerate on the scale of the liver and this unique ability will make it a prime candidate for future tissue regeneration research at AstraZeneca.
Through the development of increasingly sophisticated liver organoids, our initial aim is to mimic the process of NASH progression and advance understanding of NASH biology.
From this, our ambition is not only to identify novel targets against which we can screen potential medicines, but also to develop cell lines suitable for tissue regeneration in the liver.
Valuable insights gained from our cardiac regeneration research are now informing future directions for liver regeneration research.
By bringing together metabolic, genetic and regenerative approaches to NASH research, our ambition is to develop therapies for patients at all stages of the disease.
The liver is such a fundamental organ in the body and affected by so many serious diseases, such as NASH, that cell regeneration has huge potential for treating and possibly even, in the future, curing patients with a wide range of metabolic disorders.
References
1. National Institute of Diabetes and Digestive and Kidney Diseases. Definitions and facts of NAFLD and NASH. http://www.niddk.nih.gov/health-information/liver-disease/nafld-nash/definition-facts
2. Paik JM, Golabi P, Younossi Y et al. Changes in the Global Burden of Chronic Liver Diseases From 2012 to 2017: The Growing Impact of Nonalcoholic Fatty Liver Disease. Hepatology. 2020 Feb 11. doi: 10.1002/hep.31173. [Epub ahead of print]
3. Goldberg D, Ditah IC, Saeian K et al. Changes in the Prevalence of Hepatitis C Virus Infection, Nonalcoholic Steatohepatitis, and Alcoholic Liver Disease Among Patients With Cirrhosis or Liver Failure on the Waitlist for Liver Transplantation. Gastroenterology. 2017 Apr;152(5):1090-1099.e1.
4. European Association for the Study of the Liver (EASL); European Association for the Study of Diabetes (EASD); European Association for the Study of Obesity (EASO). EASL-EASD-EASO Clinical Practice Guidelines for the management of non-alcoholic fatty liver disease. J Hepatol. 2016 Jun;64(6):1388-402.
5. Salameh H, Hanayneh MA, Masadeh M. PNPLA3 as a Genetic Determinant of Risk for and Severity of Non-alcoholic Fatty Liver Disease Spectrum. J Clin Transl Hepatol. 2016 Sep 28;4(3):175-191.
6. Carlsson B, Lindén D, Brolén G et al. The emerging role of genetics in precision medicine for patients with non-alcoholic steatosis. Alimentary Pharmacology and Therapeutics. 7 May 2020 http://doi.org/10.1111/apt.15738
7. Lindén D, Ahnmark A, Pingitore P et al. Pnpla3 silencing with antisense oligonucleotides ameliorates nonalcoholic steatohepatitis and fibrosis in Pnpla3 I148M knock-in mice. Mol Metab. 2019 Apr;22:49-61.
8. Gastaldelli A, Cusi K. From NASH to diabetes and from diabetes to NASH: Mechanisms and treatment options. JHEP Rep. 2019 Jul 19;1(4):312-328
9. Nishi H,Higashihara T, Inagi R. Lipotoxicity in Kidney, Heart, and Skeletal Muscle Dysfunction. Nutrients. 2019 Jul; 11(7): 1664. Published online 2019 Jul 20. doi: 10.3390/nu11071664
10. Henderson SJ, Konkar A, Hornigold DC et al. Robust anti-obesity and metabolic effects of a dual GLP-1/glucagon receptor peptide agonist in rodents and non-human primates. Diabetes Obes Metab. 2016 Dec;18(12):1176-1190.
11. Ambery P, Parker VE, Stumvoll M et al. MEDI0382, a GLP-1 and glucagon receptor dual agonist, in obese or overweight patients with type 2 diabetes: a randomised, controlled, double-blind, ascending dose and phase 2a study. The Lancet 2018 Jun 30;391(10140):2607-2618.
12. Boland ML, Laker RC, Mather K et al. Resolution of NASH and hepatic fibrosis by GLP-1 1R/GcgR dual-agonist Cotadutide 2 (MEDI0382) occurs via improved mitochondrial function and reduced lipogenesis. Nature Metabolism(2020) 2: 413–431
13. Pingitore P, Sasidharan K, Ekstrand M et al. Human Multilineage 3D Spheroids as a Model of Liver Steatosis and Fibrosis. Int J Mol Sci. 2019 Apr 2;20(7). pii: E1629.
14. Prill S, Caddeo A, Baselli G et al. The TM6SF2 E167K genetic variant induces lipid biosynthesis and reduces apolipoprotein B secretion in human hepatic 3D spheroids. Sci Rep. 2019 Aug 12;9(1):11585.
