An experimental drug designed to reduce a specific risk factor for heart disease failed to prevent heart attacks and strokes in a large-scale clinical trial. Researchers reported on Saturday that the medication, pelacarsen, successfully lowered levels of a protein called lipoprotein(a), or Lp(a), but did not provide the expected clinical protection for patients over a five-year period.
The study, led by cardiologist Steven Nissen of the Cleveland Clinic and sponsored by the pharmaceutical company Novartis, focused on patients who maintain healthy lifestyles but still suffer from cardiovascular events. Scientists have long identified elevated Lp(a) levels as a common disorder linked to heart disease, affecting approximately 20% of the global population. Until recently, no medications existed that could specifically target and lower this protein.
The clinical trial involved 8,350 adults who already had established heart disease. Participants received either a placebo or pelacarsen, which suppressed Lp(a) levels by approximately 78%. Despite this reduction, the drug did not decrease the incidence of cardiovascular complications compared to the placebo group. Novartis had previously announced last month that the study did not meet its goals but did not release specific data until the American Heart Association meeting in Chicago.
The failure of the trial means that for now, patients with high Lp(a) will not see a change in their treatment options or daily medication regimens. Cardiologists noted that the results were unexpected, as the biological premise of lowering Lp(a) was widely believed to be a direct path to improving heart health. The outcome raises questions for researchers about whether Lp(a) is a direct cause of heart disease or merely a marker for other underlying issues, and whether future treatments might need to be administered earlier in life or to patients with even higher protein levels.
The results may influence the development of similar therapies currently being tested by other pharmaceutical companies. While pelacarsen did not show a clinical benefit in this specific study, other drugmakers, including Amgen and Eli Lilly, are continuing trials for their own Lp(a)-lowering medications. Data from those separate trials are expected to become available over the next few years, which will determine if the failure was specific to this drug or if the entire class of treatment requires a different approach. For now, the medical community will continue to monitor results from ongoing studies to see if different formulations or patient criteria yield different outcomes.