In an early phase multicenter clinical study,
The reductions in serum Lp(a) in patients receiving lepodisiran were dose dependent but adverse events were not, said Steven E. Nissen, MD, professor of medicine at the Cleveland Clinic Lerner College of Medicine.
Rather, drug-related adverse events “were uncommon and generally similar across all lepodisiran doses and the placebo group,” reported Dr. Nissen, who pointed out that safety and tolerability were the primary endpoints and purpose of this phase 1 study.
Lp(a) strongly associated with CV risk
Similar to LDL cholesterol (LDL-C), elevated levels of serum Lp(a) have been associated with major adverse cardiac events (MACE). In a 2022 review article that summarized pathophysiological, observational, and genetic studies, Lp(a) was found to be implicated in vascular inflammation, atherogenesis, calcification, and thrombosis.
Furthermore, Lp(a) has been associated with residual risk of cardiovascular (CV) events even after tight control of other risk factors, including elevated LDL-C, Dr. Nissen said.
So far, no well-tolerated therapy has been found to be effective for reducing Lp(a), but siRNA is a novel and attractive approach, according to Dr. Nissen, who presented these results at the annual scientific sessions of the American Heart Association. They were also published online in JAMA.
By silencing target genes, siRNA therapies can inhibit a basic step in a given pathological process. In this case, lepodisiran silences the LPA gene to halt encoding of apolipoprotein(a), which plays a key role in Lp(a) production.
Lepodisiran is not the only treatment in development for Lp(a), noted the AHA-invited discussant Michelle L. O’Donoghue, MD, chair in cardiology, Brigham and Women’s Hospital, Boston. She mentioned several other siRNA therapies, including olpasiran that was effective in a phase 2 trial she led and published in the New England Journal of Medicine.
Drugs with different mechanisms, such as the antisense oligonucleotide pelacarsen, showed activity when tested earlier this year in a phase 1 study. No study has yet been conducted to link reductions in Lp(a) with CV event risk reduction.
The current study with lepodisiran was conducted with the participation of five clinical research sites in the United States and Singapore. Participants between the ages of 18 and 65 years were enrolled if they had a serum Lp(a) of at least 75 nmol/L (30 mg/dL), which is considered moderately elevated.
They were excluded if they had CV disease or significant risk factors, including a blood pressure greater than 160/40 mm Hg, impaired renal function (eGFR < 60 mL/min per 1.73 m2), or tobacco use (> 10 cigarettes/day).
Of 340 candidates screened, 48 were randomly assigned to one placebo or six lepodisiran groups. There were 12 participants in the placebo group and 6 in each of the lepodisiran dosing groups (4 mg, 12 mg, 32 mg, 96 mg, 304 mg, and 608 mg). All doses and placebo were administered subcutaneously one time with a planned follow-up of up to 48 weeks.
Safety profile is placebo-like
The single most common adverse event, shared by those randomly assigned to placebo, was injection-site reaction. There were no adverse events, including laboratory abnormalities, that were persistent and clearly different for those assigned to any dose of lepodisiran relative to placebo.