Novel antisense inhibition of diacylglycerol O-acyltransferase 2 for treatment of non-alcoholic fatty liver disease: a multicentre, double-blind, randomised, placebo-controlled phase 2 trial

Summary

Background

Diacylglycerol-O-acyltransferase 2 (DGAT2) is one of two enzyme isoforms that catalyse the final step in the synthesis of triglycerides. IONIS-DGAT2_Rx is an antisense oligonucleotide inhibitor of DGAT2 that is under clinical investigation for the treatment of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). The aim of this trial was to examine the safety, tolerability, and efficacy of IONIS-DGAT2_Rx versus placebo in reducing liver fat in patients with type 2 diabetes and NAFLD.

Methods

This double-blind, randomised, placebo-controlled, phase 2 study consisted of a 2-week screening period, a run-in period of up to 4 weeks, a 13-week treatment period of once-weekly dosing, and a 13-week post-treatment follow-up period. The study was done at 16 clinical research sites in Canada, Poland, and Hungary. Eligible participants were aged 18–75 years, had a body-mass index at screening between 27 kg/m² and 39 kg/m², haemoglobin A_1c (HbA_1c) levels from 7·3% to 9·5%, and liver fat content 10% or greater before randomisation, and agreed to maintain a stable diet and exercise routine throughout the study. Enrolled participants were stratified on the basis of liver fat content during the run-in period (<20% or ≥20%) and then centrally randomised (2:1) to receive once weekly subcutaneous injection of 250 mg IONIS-DGAT2_Rx or placebo for 13 weeks. Participants, investigators, funder personnel, and the clinical research organisation staff, including central readers of MRI scans, were all masked to treatment identity. The primary endpoints were the safety, tolerability, and pharmacodynamic effect of IONIS-DGAT2_Rx on hepatic steatosis, according to absolute reduction from baseline in liver fat percentage as quantified by MRI-estimated proton density fat fraction and assessed in the per-protocol population. Pharmacodynamic performance was determined in the per-protocol population by the change in liver fat content from baseline to 2 weeks after the last dose. The per-protocol population included all randomised participants who received at least ten doses of study drug, with the first four doses administered in the first 5 weeks, did not miss more than three consecutive weekly doses, and who had no protocol deviations that might affect efficacy. All randomised participants who received at least one dose of study drug were included in the safety analysis. This study is registered with ClinicalTrials.gov, NCT03334214.

Findings

Between Nov 3, 2017, and Nov 28, 2018, we screened 173 people for eligibility. 44 were enrolled and randomly assigned to receive either IONIS-DGAT2_Rx (29 participants) or placebo (15 participants). After 13 weeks of treatment, the mean absolute reduction from baseline was −5·2% (SD 5·4) in the IONIS-DGAT2_Rx group compared with −0·6% (6·1) in the placebo group (treatment difference −4·2%, 95% CI −7·8 to −0·5, p=0·026). Reductions in liver fat were not accompanied by hyperlipidaemia, elevations in serum aminotransferases or plasma glucose, changes in bodyweight, or gastrointestinal side-effects compared with placebo. Six serious adverse events occurred in four patients treated with IONIS-DGAT2_Rx. No serious adverse events were reported in the placebo group. One of four patients reported three serious adverse events: acute exacerbation of chronic obstructive pulmonary disease, cardiac arrest, and ischaemic cerebral infarction, each considered severe and not related to study drug. Three of four patients reported one serious adverse event of increased blood triglycerides (severe, unrelated to study drug), deep-vein thrombosis (severe, unlikely to be related to study drug), and acute pancreatitis (mild, unrelated to study drug).

Interpretation

Our results suggest that DGAT2 antisense inhibition could be a safe and efficacious strategy for treatment of NAFLD and support further investigation in patients with biopsy-proven NASH. Based on the pharmacological target, the response to treatment observed in this study population could extend to the broader population of patients with NAFLD.

Funding

Ionis Pharmaceuticals.

Introduction

Non-alcoholic fatty liver disease (NAFLD) is considered a hepatic manifestation of metabolic syndrome,¹ initially presenting as excessive accumulation of triglycerides in the liver (ie, steatosis) in individuals who consume little or no alcohol and do not have a secondary cause for hepatic steatosis.² NAFLD is commonly associated with obesity, insulin resistance, type 2 diabetes, and metabolic syndrome.3, 4, 5 NAFLD can be broadly categorised into the following two forms: non-alcoholic fatty liver, the non-progressive form of NAFLD, and non-alcoholic steatohepatitis (NASH), the progressive form of NAFLD that can lead to progressive liver disease, fibrosis, and cirrhosis.⁶ NASH is a clinicopathological entity characterised by presence of steatosis, lobular inflammation, and ballooning with or without perisinusoidal fibrosis.²

The factors involved in progression from non-alcoholic fatty liver to NASH have not been completely elucidated, but a multiple parallel-hit hypothesis has been proposed, which suggests multiple insults act together on genetically predisposed individuals.⁷ Steatosis seems to occur first, and the disease progresses in response to secondary hits from the gut or adipose tissue, such as inflammatory cytokines, increased oxidative stress, and increased endotoxins released from the intestinal microbiome. Around 20% of people with NASH go on to develop cirrhosis and have an increased risk of developing hepatocellular carcinoma and end-stage liver disease.8, 9, 10 The risk of progression to advanced stages of disease provides a strong rationale to intervene at the initial stages, before the development of cirrhosis.

Incidence of NAFLD is rapidly increasing worldwide.¹¹ A meta-analysis estimated the global presence of NAFLD at 25% of adults, with a 59% prevalence of NASH in patients biopsied for NAFLD.12, 13 The standard of care for NAFLD and NASH is change in lifestyle, with emphasis on diet and exercise.² Studies have shown that weight loss by lifestyle intervention is associated with a significant improvement in hepatic steatosis, inflammation, and fibrosis.¹⁴ However, many patients with NAFLD have difficulty maintaining lifestyle adjustments, and pharmacological intervention could potentially be beneficial or necessary. There are, at present, no approved pharmacotherapies for NAFLD, but investigations have focused on the following four therapeutic strategies: reduction of hepatic fat accumulation; reduction of oxidative stress; correction of intestinal microbiome or dysbiosis; and reduction of hepatic fibrosis.¹⁵ Hepatic steatosis results from an imbalance between triglyceride accumulation and elimination in the liver.¹⁶ Insulin resistance is closely linked with this process because it alters nutrient metabolism and distribution among tissues and leads to an influx of free fatty acids into the liver due to decreased suppression of lipolysis and increased lipogenesis.

Interruption of triglyceride synthesis presents a novel drug mechanism for the treatment of metabolic diseases such as NAFLD. In this approach, inhibition of hepatic lipogenesis reduces the primary hit of hepatic steatosis, which might then prevent subsequent injury related to toxic lipid species and could attenuate the secondary hits that ultimately lead to irreversible disease progression. Initial data with a small-molecule inhibitor of acetyl-coenzyme A carboxylase showed that, although reduction in steatosis can be achieved by reducing de-novo lipogenesis, this is accompanied by an increase in serum triglycerides,¹⁷ thereby potentially limiting the clinical use of such an approach in patients with concomitant hypertriglyceridaemia. Diacylglycerol-O-acyltransferase (DGAT) catalyses the final step of triglyceride synthesis by facilitating the linkage of diacylglycerol to acyl-coenzyme A (appendix p 11). DGAT has two isoforms, DGAT1 and DGAT2. Both are expressed in white adipose tissue; elsewhere, DGAT1 is most highly expressed in the small intestine, whereas DGAT2 is primarily expressed in the liver. The isoforms are also distinguished by their catalytic properties,18, 19 subcellular localisation,²⁰ physiological regulation,²¹ and phenotypic consequences when rendered deficient²² or overexpressed in preclinical models.²³ In two rodent models,24, 25 antisense inhibition of DGAT2, but not DGAT1, decreased hepatic triglyceride levels, improved hepatic steatosis and plasma lipoprotein profiles, and decreased triglyceride synthesis. These changes were associated with a compensatory decrease in mRNA expression of several other hepatic lipogenic genes, including the acetyl-coenzyme A carboxylases and stearoyl coenzyme A desaturase 1. Additionally, there is evidence of an increase in both fatty acid oxidation and oxidative gene expression associated with antisense inhibition of DGAT2.24, 25

IONIS-DGAT2_Rx (Ionis Pharmaceuticals; Carlsbad, CA, USA) is a 2'-O-methoxyethyl chimeric antisense oligonucleotide inhibitor designed to support enzyme-mediated degradation of DGAT2 mRNA to prevent production of DGAT2 protein. In a phase 1 study involving 40 healthy, overweight volunteers, IONIS-DGAT2_Rx was safe and well tolerated. To our knowledge, no published studies have clinically evaluated a DGAT2 inhibitor for the treatment of NAFLD.¹⁶ Here, we report the safety, tolerability, and clinical findings from a randomised, placebo-controlled, phase 2 trial of IONIS-DGAT2_Rx in patients with type 2 diabetes and NAFLD.