Nonalcoholic fatty liver disease consists of a spectrum starting from nonalcoholic fatty liver disease that may progress to nonalcoholic steatohepatitis (NASH), which can lead to fibrosis, cirrhosis, hepatocellular carcinoma, or even liver failure. The prevalence of NASH has increased in parallel with the rising rate of obesity and type 2 diabetes. Given the high prevalence and deadly complications of NASH, there have been significant efforts to develop effective treatments. Phase 2A studies have assessed various mechanisms of action across the spectrum of the disease, while phase 3 studies have focused mainly on NASH and fibrosis stage 2 and higher, as these patients have a higher risk of disease morbidity and mortality. The primary efficacy endpoints also vary, by using noninvasive tests in early-phase trials while relying on liver histological endpoints in phase 3 studies as required by regulatory agencies. Despite initial disappointment due to the failure of several drugs, recent phase 2 and 3 studies have shown promising results, with the first Food and Drug Administration-approved drug for NASH expected to be approved in 2023. In this review, we discuss the various drugs under development for NASH, their mechanisms of action, and the results of their clinical trials. We also highlight the potential challenges in developing pharmacological therapies for NASH.

BACKGROUND: Liver histopathologic assessment is the accepted surrogate endpoint in NASH trials; however, the scoring of NASH Clinical Research Network (CRN) histologic parameters is limited by intraobserver and interobserver variability. We designed a consensus panel approach to minimize variability when using this scoring system. We assessed agreement between readers, estimated linear weighted kappas between 2 panels, compared them with published pairwise kappa estimates, and addressed how agreement or disagreement might impact the precision and validity of the surrogate efficacy endpoint in NASH trials. METHODS: Two panels, each comprising 3 liver fellowship-trained pathologists who underwent NASH histology training, independently evaluated scanned whole slide images, scoring fibrosis, inflammation, hepatocyte ballooning, and steatosis from baseline and month 18 biopsies for 100 patients from the precirrhotic NASH study REGENERATE. The consensus score for each parameter was defined as agreement by ≥2 pathologists. If consensus was not reached, all 3 pathologists read the slide jointly to achieve a consensus score. RESULTS: Between the 2 panels, the consensus was 97%-99% for steatosis, 91%-93% for fibrosis, 88%-92% for hepatocyte ballooning, and 84%-91% for inflammation. Linear weighted kappa scores between panels were similar to published NASH CRN values. CONCLUSIONS: A panel of 3 trained pathologists independently scoring 4 NASH CRN histology parameters produced high consensus rates. Interpanel kappa values were comparable to NASH CRN metrics, supporting the accuracy and reproducibility of this method. The high concordance for fibrosis scoring was reassuring, as fibrosis is predictive of liver-specific outcomes and all-cause mortality.

Background

Serum biomarkers of steatosis such as the SteatoTest are recommended for large-scale screening studies, because imaging is less accessible and more expensive.

Aims

The primary aim of this retrospective analysis of prospective studies was to construct a new SteatoTest-2 that was not inferior to the reference first-generation SteatoTest, but that did not include BMI or bilirubin, as these two components can increase test variability because of the assessment of weight and height and in case of Gilbert syndrome or hemolysis, respectively.

Patients and methods

Five different subsets of 2997 patients with biopsies were evaluated for test construction and validation, and four to assess the prevalence of steatosis in target populations with increasing risks of steatosis. The performance of the SteatoTest-2 was compared with the reference test, using the noninferiority test (0.10 margin) and the Lin concordance coefficient.

Results

Areas under the receiver operating characteristic curve of the SteatoTest-2 were noninferior to the reference test (P<0.001). Areas under the receiver operating characteristic curve varied in the SteatoTest-2 and the reference test according to subsets and the prevalence of steatosis, with 0.772 [95% confidence interval (CI): 0.713-0.820] versus 0.786 (95% CI: 0.729-0.832) in the 2997 cases with biopsy and 0.822 (95% CI: 0.810-0.834) versus 0.868 (95% CI: 0.858-0.878) in the 5776 cases including healthy individuals without risk factors of steatosis as controls, respectively. The Lin coefficient was highly concordant (P<0.001), from 0.74 (95% CI: 0.74-0.74) in presumed NAFLD to 0.91 (95% CI: 0.89-0.93) in the construction subset.

Conclusion

The SteatoTest-2 is simpler and noninferior to the first-generation SteatoTest for the diagnosis of steatosis, without the limitations of BMI and bilirubin.

Background

Non-alcoholic steatohepatitis (NASH) is a progressive form of non-alcoholic fatty liver disease (NAFLD) associated with steatosis, hepatocellular injury, inflammation and fibrosis. In a Phase 2 trial in adults with NASH (NCT02912260), resmetirom, an orally administered, liver-targeted thyroid hormone receptor-β selective agonist, significantly reduced hepatic fat (via imaging) and resolved NASH without worsening fibrosis (via liver biopsy) in a significant number of patients compared with placebo.

Aims

To present the design of the Phase 3 MAESTRO clinical programme evaluating resmetirom for treatment of NASH (MAESTRO-NAFLD-1 [NCT04197479], MAESTRO-NAFLD-OLE [NCT04951219], MAESTRO-NASH [NCT03900429], MAESTRO-NASH-OUTCOMES [NCT05500222]).

Methods

MAESTRO-NASH is a pivotal serial biopsy trial in up to 2000 adults with biopsy-confirmed at-risk NASH. Patients are randomised to a once-daily oral placebo, 80 mg resmetirom, or 100 mg resmetirom. Liver biopsies are conducted at screening, week 52 and month 54. MAESTRO-NAFLD-1 is a 52-week safety trial in ~1400 adults with NAFLD/presumed NASH (based on non-invasive testing); ~700 patients from MAESTRO-NAFLD-1 are enrolled in MAESTRO-NAFLD-OLE, a 52-week active treatment extension to further evaluate safety. MAESTRO-NASH-OUTCOMES is enrolling 700 adults with well-compensated NASH cirrhosis to evaluate the potential for resmetirom to slow progression to hepatic decompensation events. Non-invasive tests (biomarkers, imaging) are assessed longitudinally throughout, in addition to validated patient-reported outcomes.

Conclusion

The MAESTRO clinical programme was designed in conjunction with regulatory authorities to support approval of resmetirom for treatment of NASH. The surrogate endpoints, based on week 52 liver biopsy, serum biomarkers and imaging, are confirmed by long-term clinical liver-related outcomes in MAESTRO-NASH (month 54) and MAESTRO-NASH-OUTCOMES (time to event).

Background

Patients with non-alcoholic steatohepatitis (NASH)-related cirrhosis are at high risk of liver-related and all-cause morbidity and mortality. We investigated the efficacy and safety of the glucagon-like peptide-1 analogue semaglutide in patients with NASH and compensated cirrhosis.

Methods

This double-blind, placebo-controlled phase 2 trial enrolled patients from 38 centres in Europe and the USA. Adults with biopsy-confirmed NASH-related cirrhosis and body-mass index (BMI) of 27 kg/m² or more were randomly assigned (2:1) to receive either once-weekly subcutaneous semaglutide 2·4 mg or visually matching placebo. Patients were randomly allocated via an interactive web response system, stratified by presence or absence of type 2 diabetes. Patients, investigators, and those assessing outcomes were masked to treatment assignment. The primary endpoint was the proportion of patients with an improvement in liver fibrosis of one stage or more without worsening of NASH after 48 weeks, assessed by biopsy in the intention-to-treat population. Safety was assessed in all patients who received at least one dose of study drug. The trial is closed and completed, and registered with ClinicalTrials.gov, number NCT03987451.

Findings

71 patients were enrolled between June 18, 2019, and April 22, 2021; 49 (69%) patients were female and 22 (31%) were male. Patients had a mean age of 59·5 years (SD 8·0) and mean BMI of 34·9 kg/m² (SD 5·9); 53 (75%) patients had diabetes. 47 patients were randomly assigned to the semaglutide group and 24 to the placebo group. After 48 weeks, there was no statistically significant difference between the two groups in the proportion of patients with an improvement in liver fibrosis of one stage or more without worsening of NASH (five [11%] of 47 patients in the semaglutide group vs seven [29%] of 24 in the placebo group; odds ratio 0·28 [95% CI 0·06-1·24; p=0·087). There was also no significant difference between groups in the proportion of patients who achieved NASH resolution (p=0·29). Similar proportions of patients in each group reported adverse events (42 [89%] patients in the semaglutide group vs 19 [79%] in the placebo group) and serious adverse events (six [13%] vs two [8%]). The most common adverse events were nausea (21 [45%] vs four [17%]), diarrhoea (nine [19%] vs two [8%]), and vomiting (eight [17%] vs none). Hepatic and renal function remained stable. There were no decompensating events or deaths.

Interpretation

In patients with NASH and compensated cirrhosis, semaglutide did not significantly improve fibrosis or achievement of NASH resolution versus placebo. No new safety concerns were raised.

Funding

Novo Nordisk A/S.