Antisense oligonucleotides targeting apolipoprotein(a) in people with raised lipoprotein(a): two randomised, double-blind, placebo-controlled, dose-ranging trials

Summary

Background

Elevated lipoprotein(a) (Lp[a]) is a highly prevalent (around 20% of people) genetic risk factor for cardiovascular disease and calcific aortic valve stenosis, but no approved specific therapy exists to substantially lower Lp(a) concentrations. We aimed to assess the efficacy, safety, and tolerability of two unique antisense oligonucleotides designed to lower Lp(a) concentrations.

Methods

We did two randomised, double-blind, placebo-controlled trials. In a phase 2 trial (done in 13 study centres in Canada, the Netherlands, Germany, Denmark, and the UK), we assessed the effect of IONIS-APO(a)_Rx, an oligonucleotide targeting apolipoprotein(a). Participants with elevated Lp(a) concentrations (125–437 nmol/L in cohort A; ≥438 nmol/L in cohort B) were randomly assigned (in a 1:1 ratio in cohort A and in a 4:1 ratio in cohort B) with an interactive response system to escalating-dose subcutaneous IONIS-APO(a)_Rx (100 mg, 200 mg, and then 300 mg, once a week for 4 weeks each) or injections of saline placebo, once a week, for 12 weeks. Primary endpoints were mean percentage change in fasting plasma Lp(a) concentration at day 85 or 99 in the per-protocol population (participants who received more than six doses of study drug) and safety and tolerability in the safety population. In a phase 1/2a first-in-man trial, we assessed the effect of IONIS-APO(a)-L_Rx, a ligand-conjugated antisense oligonucleotide designed to be highly and selectively taken up by hepatocytes, at the BioPharma Services phase 1 unit (Toronto, ON, Canada). Healthy volunteers (Lp[a] ≥75 nmol/L) were randomly assigned to receive a single dose of 10–120 mg IONIS-APO(a)L_Rx subcutaneously in an ascending-dose design or placebo (in a 3:1 ratio; single-ascending-dose phase), or multiple doses of 10 mg, 20 mg, or 40 mg IONIS-APO(a)L_Rx subcutaneously in an ascending-dose design or placebo (in an 8:2 ratio) at day 1, 3, 5, 8, 15, and 22 (multiple-ascending-dose phase). Primary endpoints were mean percentage change in fasting plasma Lp(a) concentration, safety, and tolerability at day 30 in the single-ascending-dose phase and day 36 in the multiple-ascending-dose phase in participants who were randomised and received at least one dose of study drug. In both trials, the randomised allocation sequence was generated by Ionis Biometrics or external vendor with a permuted-block randomisation method. Participants, investigators, sponsor personnel, and clinical research organisation staff who analysed the data were all masked to the treatment assignments. Both trials are registered with ClinicalTrials.gov, numbers NCT02160899 and NCT02414594.

Findings

From June 25, 2014, to Nov 18, 2015, we enrolled 64 participants to the phase 2 trial (51 in cohort A and 13 in cohort B). 35 were randomly assigned to IONIS-APO(a)_Rx and 29 to placebo. At day 85/99, participants assigned to IONIS-APO(a)_Rx had mean Lp(a) reductions of 66·8% (SD 20·6) in cohort A and 71·6% (13·0) in cohort B (both p<0·0001 vs pooled placebo). From April 15, 2015, to Jan 11, 2016, we enrolled 58 healthy volunteers to the phase 1/2a trial of IONIS-APO(a)-L_Rx. Of 28 participants in the single-ascending-dose phase, three were randomly assigned to 10 mg, three to 20 mg, three to 40 mg, six to 80 mg, six to 120 mg, and seven to placebo. Of 30 participants in the multiple-ascending-dose phase, eight were randomly assigned to 10 mg, eight to 20 mg, eight to 40 mg, and six to placebo. Significant dose-dependent reductions in mean Lp(a) concentrations were noted in all single-dose IONIS-APO(a)-L_Rx groups at day 30. In the multidose groups, IONIS-APO(a)-L_Rx resulted in mean reductions in Lp(a) of 66% (SD 21·8) in the 10 mg group, 80% (SD 13·7%) in the 20 mg group, and 92% (6·5) in the 40 mg group (p=0·0007 for all vs placebo) at day 36. Both antisense oligonucleotides were safe. There were two serious adverse events (myocardial infarctions) in the IONIS-APO(a)_Rx phase 2 trial, one in the IONIS-APO(a)_Rx and one in the placebo group, but neither were thought to be treatment related. 12% of injections with IONIS-APO(a)_Rx were associated with injection-site reactions. IONIS-APO(a)-L_Rx was associated with no injection-site reactions.

Interpretation

IONIS-APO(a)-L_Rx is a novel, tolerable, potent therapy to reduce Lp(a) concentrations. IONIS-APO(a)-L_Rx might mitigate Lp(a)-mediated cardiovascular risk and is being developed for patients with elevated Lp(a) concentrations with existing cardiovascular disease or calcific aortic valve stenosis.

Funding

Ionis Pharmaceuticals.

Introduction

Cardiovascular disease continues to be the major cause of morbidity and mortality worldwide, despite advancements in diagnosis and therapy. Genetic association and mendelian randomisation studies have shown a causal association between genetic variants associated with apolipoprotein B (apoB)-containing lipoproteins and cardiovascular disease.1, 2, 3, 4, 5 These observations are in line with natural history studies and clinical trials showing that either lifelong low levels of apoB-containing lipoproteins or therapeutic interventions that lower apoB-containing lipoproteins are associated with reduced risk of cardiovascular disease events.⁶ However, despite achievement of very low LDL cholesterol (LDL-C) with statins or other lipid-modulating therapies, substantial residual risk of cardiovascular disease remains. For example, in the IMPROVE-IT trial,⁷ patients treated with simvastatin and ezetimibe after acute coronary syndromes achieved a mean LDL-C concentration of 53 mg/dL, but at this level of reduction, 32% of participants continued to have major adverse cardiac events over 6 years and only a 2% absolute risk reduction of cardiovascular disease was present.

Lipoprotein(a) (Lp[a]) is a modified LDL particle that is composed of LDL and apolipoprotein(a) (apo[a]). Lp(a) is now recognised as a major and independent risk factor for cardiovascular disease and calcific aortic valve stenosis.8, 9, 10 On a molar basis, Lp(a) appears to be more atherogenic than LDL since it mediates cardiovascular disease risk not only from its LDL-like moiety but also its apo(a) component, as well as its content of proinflammatory oxidised phospholipids (OxPL).11, 12, 13, 14 Lp(a) concentrations are not appreciably altered by commonly used available therapies and indeed, statin therapy does not lower, and might even increase, Lp(a) concentrations.¹⁵ Additionally, despite LDL-C reduction, elevated Lp(a) was a risk factor for additional cardiovascular disease events in AIM-HIGH (final median LDL-C 62 mg/dL),¹⁶ LIPID (mean LDL-C 112 mg/dL),¹⁷ and JUPITER (final mean LDL-C 55 mg/dL) trials.¹⁸ Although niacin,¹⁹ mipomersen,²⁰ and PCSK9 inhibitors²¹ modestly lower Lp(a) by about 20–30%, until now, neither specific nor potent therapies were available to reduce Lp(a).

In a recent phase 1 trial of healthy people, we showed dose-dependent, potent reductions in plasma Lp(a) concentrations after therapy with IONIS-APO(a)_Rx (previously called ISIS-APO(a)_Rx), an antisense oligonucleotide targeting hepatic apo(a) mRNA.²² IONIS-APO(a)-L_Rx is a ligand-conjugated antisense oligonucleotide variant of IONIS-APO(a)_Rx with a triantennary N-acetylgalactosamine (GalNAc₃) complex covalently attached to allow rapid and specific uptake within hepatocytes via the asialoglycoprotein (ASGP) receptor as well as the replacement of six of the 19 phosphorothioate linkages and with phosphodiester linkages at positions 2, 3, 4, 5, 16, and 17 (appendix).²³ Here we report the findings of a phase 2 trial with IONIS-APO(a)_Rx in participants with elevated Lp(a) concentrations. We also report the first-in-man application of IONIS-APO(a)-L_Rx in healthy volunteers.