ARO-HSD is a hepatocyte targeted siRNA therapeutic designed to silence HSD17β13 expression g D17β13 express ARO-HSD Favorable safety profile ARO-HSD was well tolerated with no treatment-related serious adverse events or drug discontinuations Proof of concept In this proof-of-concept study, ARO-HSD was well tolerated and able to significantly reduce HSD17β13 expression in a group of 18 patients, resulting in an improvement in markers of liver injury 18 Patients with suspected or confirmed NASH 16 Healthy volunteers ALT reduction -42.3% Mean change from baseline at day 71 at 200 mg HSD17β13 loss-of-function mutations have been shown to protect against alcoholic and non-alcoholic liver disease including NASH 16 Hepatic HSD17β13 mRNA reduction-93.4%Reduction from baseline at day 71 at 200 mg Hepatic HSD17β13 protein reduction -83.0%Reduction from baseline at day 71 at 200 mg Highlights HSD17B13 loss-of-function mutations are protective against alcohol-related and non-alcoholic liver disease, including NASH.ARO-HSD is a hepatocyte-targeted siRNA therapeutic designed to silence HSD17B13 expression.ARO-HSD demonstrated a favorable safety profile in healthy volunteers and patients with suspected NASH.Mean change from baseline at Day 71 in hepatic HSD17b13 mRNA was -93.4% (ARO-HSD 200 mg).

Background & Aims: Loss-of-function HSD17613 mutations protect against the development of chronic liver disease. HSD17613 inhibition represents a potential approach to treat liver diseases, such as non-alcoholic steatohepatitis (NASH). ARO-HSD is an RNA interference (RNAi) therapeutic designed to selectively reduce expression of HSD17#13 mRNA in hepatocytes. In this study, we evaluated the effects of ARO-HSD in normal healthy volunteers (NHVs) and patients with confirmed or clinically sus-pected NASH. Methods: The safety, tolerability, and pharmacodynamics of ARO-HSD were evaluated in 32 NHVs and 18 patients with confirmed/clinically suspected NASH. Double-blind NHV cohorts received single escalating doses of ARO-HSD (25, 50, 100, or 200 mg) or placebo subcutaneously on Day 1. Open-label patient cohorts received ARO-HSD (25, 100, or 200 mg) subcutaneously on Days 1 and 29. Liver biopsy was performed pre-dose and on Day 71 to evaluate expression levels of HSD17#13 mRNA and protein. Results: ARO-HSD treatment was well tolerated with no treatment-related serious adverse events or drug discontinuations. The most frequently reported treatment-emergent adverse events were mild injection site reactions, which were short in duration. Mean changes in hepatic HSD17#13 mRNA from baseline to Day 71 were:-56.9% (25 mg),-85.5% (100 mg), and-93.4% (200 mg). The mean HSD17#13 mRNA reduction was 78.6% (p <0.0001) across pooled cohorts. Hepatic HSD17613 protein levels were similarly reduced across doses. In patients, mean changes in alanine aminotransferase from baseline to Day 71 were-7.7% (25 mg),-39.3% (100 mg), and-42.3% (200 mg) (p <0.001 for pooled cohorts). Conclusions: ARO-HSD was well tolerated at doses <-200 mg. This proof-of-concept study demonstrated that short-term treatment with ARO-HSD reduces hepatic HSD17#13 mRNA and protein expression, which is accompanied by reductions in alanine aminotransferase.

The autosomal codominant genetic disorder alpha-1 antitrypsin (AAT) deficiency (AATD) causes pulmonary and liver disease. Individuals homozygous for the mutant Z allele accumulate polymers of Z-AAT protein in hepatocytes, where AAT is primarily produced. This accumulation causes endoplasmic reticulum (ER) stress, oxidative stress, damage to mitochondria, and inflammation, leading to fibrosis, cirrhosis, and hepatocellular carcinoma. The magnitude of AAT reduction and duration of response from first-generation intravenously administered RNA interference (RNAi) therapeutic ARC-AAT and then with next-generation subcutaneously administered ARO-AAT were assessed by measuring AAT protein in serum of the PiZ transgenic mouse model and human volunteers. The impact of Z-AAT reduction by RNAi on liver disease phenotypes was evaluated in PiZ mice by measuring polymeric Z-AAT in the liver; expression of genes associated with fibrosis, autophagy, apoptosis, and redox regulation; inflammation; Z-AAT globule parameters; and tumor formation. Ultrastructure of the ER, mitochondria, and autophagosomes in hepatocytes was evaluated by electron microscopy. In mice, sustained RNAi treatment reduced hepatic Z-AAT polymer, restored ER and mitochondrial health, normalized expression of disease-associated genes, reduced inflammation, and prevented tumor formation. RNAi therapy holds promise for the treatment of patients with AATD-associated liver disease. ARO-AAT is currently in phase II/III clinical trials.

Background & Aims: Alpha-1 antitrypsin deficiency (AATD) is a genetic disorder causing pulmonary and liver disease. The PiZ mutation in AAT (SERPINA1) results in mis-folded AAT protein (Z-AAT) accumulating in hepatocytes, leading to fibrosis and cirrhosis. RNAi-based therapeutics silencing production of hepatic Z-AAT might benefit patients with AATD-associated liver disease. This study evaluated an RNAi therapeutic to silence production of AAT. Methods: Part A of this double-blind first-in-human study randomized 54 healthy volunteers (HVs) into single dose cohorts (two placebo: four active), receiving escalating doses of the investigational agent ARC-AAT from 0.38 to 8.0 mg/kg or placebo. Part B randomized 11 patients with PiZZ (homozygous for Z-AAT) genotype AATD, who received up to 4.0 mg/kg of ARC-AAT or placebo. Patients with baseline FibroScan (c) > 11 kPa or forced expiratory volume in one second (FEV1) < 60% were excluded. Assessments included safety, pharmacokinetics, and change in serum AAT concentrations. Results: A total of 36 HVs received ARC-AAT and 18 received placebo (part A). Seven PiZZ individuals received ARC-AAT and four received placebo (part B). A dose response in serum AAT reduction was observed at doses >= 4 mg/kg with similar relative reductions in PiZZ patients and HVs at 4 mg/kg and a maximum reduction of 76.1% (HVs) vs. 78.8% (PiZZ) at this dose. The time it took for serum AAT to return to baseline was similar for HV and PiZZ. There were no notable differences between HV and PiZZ safety parameters. The study was terminated early because of toxicity findings related to the delivery vehicle (ARC-EX1) seen in a non-human primate study. Conclusion: PiZZ patients and HVs responded similarly to ARCAAT. Deep and durable knockdown of hepatic AAT production based on observed reduction in serum AAT concentrations was demonstrated. Lay summary: Accumulation of abnormal proteins in the livers of patients with alpha-1 antitrypsin deficiency may lead to decreased liver function and potentially liver failure. Therapeu-tics targeting the production of these abnormal proteins may be used to prevent or treat liver disease in patients with alpha-1 antitrypsin deficiency. (C) 2018 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

PURPOSE: Alpha-1 antitrypsin deficiency (AATD) is an autosomal recessive genetic disorder that causes pulmonary disease in adults and liver disease in children and adults.Wild type alpha-1 antitrypsin (AAT) is a 52 kDa circulating glycoprotein produced primarily in liver hepatocytes (~90% of total).The E342K substitution, known as the PiZ mutation, results in improper AAT processing and impairs its secretion by hepatocytes.Individuals homozygous for the PiZ allele (PiZZ) have very low serum concentrations of the Z mutant AAT (Z-AAT) and accumulate Z-AAT aggregates in hepatocytes.These aggregates lead to a recurrent cycle of hepatocyte injury and associated fibrosis, which over time leads to liver disease including cirrhosis and hepatocellular carcinoma.We are currently developing a RNAi-based therapeutic to reduce Z-AAT aggregates in liver, which we propose will prevent the progression and development of AATD-associated liver disease in PiZZ individuals.METHODS: A set of RNAi triggers targeting AAT was designed using bioinformatic algorithms and screened for activity in cells in culture.Highly active RNAi triggers were further modified by incorporating unlocked nucleobase analogs (UNAs).The most potent UNAs were tested in a transgenic mouse model expressing the human PiZ mutant allele.In vivo delivery was accomplished by conjugating the UNAs to cholesterol (chol-UNA) to enhance liver uptake and co-injecting each with a hepatocyte targeted and reversibly masked peptide (MLP-(CDM-NAG) designed to enhance endosomal escape.RESULTS: Intravenous injection of candidate chol-UNAs with MLP-(CDM-NAG) led to dose-dependent inhibition of serum Z-AAT of up to 98% in PiZ mice.Reduced levels of serum Z-AAT (>90%) were sustained in PiZ mice given four biweekly injections of the most potent chol-UNA with MLP-(CDM-NAG).In the livers of these mice, greatly reduced levels of soluble and Z-AAT aggregates were observed coincident with improved liver histology.As an indicator of the potency and duration of effect that might be expected in humans, a single co-injection of chol-UNA and MLP-(CDM-NAG) was performed in cynomolgus monkeys.This led to >90% KD of serum AAT with a duration of effect of greater than one month.CONCLUSION: These results demonstrate dramatic and long-lasting reduction of AAT following co-injection of chol-UNA and MLP-(CDM-NAG) in the PiZ mouse and in cynomolgus monkeys.Repeat dosing prevented and even reversed accumulation of Z-AAT aggregates in the PiZ mouse model, the cause of liver disease.This RNAi therapeutic holds great promise for the treatment of patients with AATD-associated liver disease.