Novartis Heart Drug Fails Major Trial, Raising Questions Over Genetic Cholesterol Treatment

NEW YORK, Nov 2: A major clinical trial failure involving an experimental heart medicine developed by Novartis and Ionis Pharmaceuticals has raised fresh questions about whether lowering a genetically determined form of cholesterol can significantly reduce the risk of cardiovascular disease.

The medicine, pelacarsen, had attracted considerable attention from the medical and pharmaceutical industries because of its ability to reduce levels of lipoprotein(a), commonly known as Lp(a). However, despite demonstrating a substantial reduction in the cholesterol-related particle, the treatment failed to achieve the primary objective of its Phase 3 clinical trial.

The outcome has created uncertainty among cardiologists and researchers who had viewed Lp(a) as a promising target for preventing heart attacks and other serious cardiovascular complications.

Pelacarsen was developed to address elevated Lp(a) levels, a condition largely determined by inherited genetic factors. Unlike conventional low-density lipoprotein (LDL), often referred to as bad cholesterol, Lp(a) levels are generally not significantly influenced by diet, physical activity or other lifestyle modifications.

According to available trial findings, pelacarsen reduced Lp(a) concentrations by approximately 80 per cent. However, this biochemical improvement did not translate into a statistically significant reduction in the combined risk of death, heart attack, stroke and procedures required to restore blood circulation in blocked arteries.

The failure has prompted renewed debate over whether lowering Lp(a) directly produces meaningful cardiovascular benefits or whether the particle primarily serves as an indicator of inherited heart disease risk.

The detailed results are expected to provide further information about the treatment’s performance and help researchers understand the reasons behind the outcome.
Why Lipoprotein(a) Has Attracted Medical Attention
Lipoprotein(a) is a cholesterol-containing particle produced by the liver. Its structure resembles LDL cholesterol but includes an additional protein called apolipoprotein(a).

Elevated levels have been associated with an increased risk of cardiovascular conditions, including coronary artery disease, heart attacks and aortic valve disease.

Medical researchers estimate that approximately one in five people worldwide has genetically determined Lp(a) levels that may increase their cardiovascular risk. The prevalence is higher in certain population groups, including people of African and South Asian ancestry.

Unlike many other cardiovascular risk factors, Lp(a) levels are largely inherited and generally remain relatively stable throughout a person’s lifetime.

This makes the condition particularly challenging because conventional approaches to controlling cholesterol, including dietary changes, regular exercise and weight management, do not substantially reduce Lp(a).

Lifestyle improvements remain important for overall cardiovascular health, but they cannot be relied upon to lower genetically elevated levels of this particular particle.

For years, doctors have been able to identify patients with elevated Lp(a) through blood testing, but specific medicines designed to substantially reduce the particle and demonstrate improved cardiovascular outcomes have remained an important unmet medical need.

The development of pelacarsen therefore represented a potentially significant step towards a new approach to cardiovascular prevention.
Phase 3 Trial Results Disappoint Researchers
The Phase 3 study was designed to determine whether reducing Lp(a) levels with pelacarsen could prevent major cardiovascular events among patients at risk.

The medicine was developed using an approach intended to interfere with the production of apolipoprotein(a) in the liver, thereby reducing the amount of Lp(a) circulating in the bloodstream.

Although earlier studies demonstrated substantial reductions in the particle, the larger trial did not meet its primary endpoint.

The main objective involved reducing a combination of serious medical events, including cardiovascular death, heart attacks, strokes and procedures to restore blood flow through blocked arteries.

The failure to demonstrate a statistically significant improvement has raised concerns about the assumptions underpinning the treatment strategy.

However, cardiologists have cautioned against drawing immediate conclusions before reviewing the complete clinical findings.

Researchers are particularly interested in understanding whether the medicine produced any meaningful reduction in individual outcomes, such as heart attacks or the need for procedures to reopen blocked arteries.

The distinction is important because a clinical trial’s primary endpoint may combine several different medical events. A treatment could potentially influence certain outcomes without producing a sufficiently large overall improvement to meet the study’s statistical target.

Dr Parag Joshi, a cardiologist at UT Southwestern Medical Center and an investigator in the study, said the detailed findings would be important in determining the future prospects of medicines targeting Lp(a).

The complete trial results are scheduled for presentation at the American Heart Association’s annual scientific meeting in Chicago.
Questions Over Dosage and Other Treatments
Several factors are being examined by specialists to understand why the substantial reduction in Lp(a) did not produce the expected cardiovascular benefits.

One issue concerns the dosage used in the trial. Pelacarsen was administered at a monthly dose of 80 milligrams, a regimen that had not previously been tested at that level in the same manner.

Earlier mid-stage research had evaluated a maximum monthly dose of 60 milligrams, alongside a weekly 20-milligram schedule.

Some researchers have raised questions about whether the higher monthly dosage could have affected treatment tolerance or contributed to participants discontinuing the medicine.

Another consideration involves the other cardiovascular medicines taken by participants during the study.

Patients received either pelacarsen or a placebo alongside standard cholesterol-lowering treatments, including statins and PCSK9 inhibitors.

These medicines are designed primarily to reduce LDL cholesterol and have become increasingly important in managing patients with elevated cardiovascular risk.

PCSK9 inhibitors can also produce a more modest reduction in Lp(a), potentially influencing the difference between the treatment and comparison groups.

Researchers are therefore interested in determining whether the increased use of these medicines during the trial affected the ability to identify an additional benefit from pelacarsen.

The study also included stroke within its combined primary endpoint. Some specialists have questioned whether this was the most appropriate measure, given that the relationship between Lp(a) and stroke remains less clearly established than its association with certain other cardiovascular conditions.

These questions do not establish why the trial failed, but they highlight the importance of examining the complete data before determining the implications for future drug development.
Other Pharmaceutical Companies Continue Research
Despite the disappointing result, the broader pharmaceutical industry has not abandoned efforts to develop treatments targeting Lp(a).

Companies including Amgen and Eli Lilly are advancing experimental medicines that use different mechanisms to reduce the particle.

Amgen’s olpasiran and Eli Lilly’s lepodisiran have demonstrated reductions in Lp(a) levels of approximately 95 per cent in earlier clinical studies.

Both programmes are being closely monitored because they could provide additional evidence about whether substantially lowering the inherited cholesterol particle can reduce cardiovascular complications.

Amgen’s Phase 3 results are expected in early 2028, while Eli Lilly’s major trial findings are anticipated in 2029.

The studies differ from the Novartis programme in several respects, including their design and the selection of participants. Some of the other trials are enrolling patients with higher baseline Lp(a) levels, which could help researchers determine whether the degree of inherited cholesterol elevation influences treatment outcomes.

The results could also help establish whether particular patient groups are more likely to benefit from targeted therapies.

For now, researchers say the failure of one medicine should not automatically be interpreted as proof that the entire treatment approach is ineffective.
Blood Testing Could Help Identify Inherited Risk
Although the trial outcome has disappointed researchers, medical professionals continue to regard Lp(a) testing as a useful tool for identifying people who may have an inherited risk of cardiovascular disease.

The American Heart Association and the American College of Cardiology have recommended that adults have their Lp(a) levels measured at least once during their lifetime.

The recommendation reflects the genetic nature of the condition and the fact that many people may have elevated levels without experiencing obvious symptoms.

Testing can be particularly relevant for individuals with a family history of premature heart disease or patients who develop cardiovascular complications despite having relatively controlled conventional cholesterol levels.

Dr Nathaniel Lebowitz, a cardiologist at Hackensack University Medical Center who helped develop the guidelines, has highlighted the importance of considering inherited Lp(a) levels when assessing patients with a family history of early cardiovascular disease.

Identifying elevated levels may help doctors evaluate a patient’s overall risk and make decisions about managing other contributing factors.

However, a high Lp(a) result does not mean that a person will inevitably develop heart disease. It is one component of a broader cardiovascular risk assessment.

Doctors may consider blood pressure, diabetes, smoking, LDL cholesterol, family history and other medical conditions when developing an appropriate prevention strategy.
What the Trial Failure Means for Future Heart Disease Treatment
The outcome of the pelacarsen study represents a setback for a field that had generated considerable optimism about the possibility of directly targeting genetically determined cholesterol.

For pharmaceutical companies, the findings underline the difference between successfully changing a biological marker and demonstrating that the change improves patients’ health.

Reducing a substance associated with disease does not necessarily guarantee fewer heart attacks, strokes or deaths. Large clinical trials remain essential for establishing whether a treatment provides meaningful benefits beyond measurable changes in laboratory results.

For patients, the findings do not change the importance of established cardiovascular prevention measures.

Controlling LDL cholesterol, maintaining healthy blood pressure, managing diabetes, avoiding tobacco and following appropriate medical advice remain important ways to reduce cardiovascular risk.

The trial also highlights the need for continued research into inherited risk factors that cannot be adequately addressed through conventional lifestyle interventions.

As detailed findings become available, cardiologists will examine whether pelacarsen showed benefits in specific patient groups, whether the treatment’s dosage influenced its performance and whether other medicines affected the results.

The findings from competing drug-development programmes will also be important in determining whether the Lp(a) pathway remains a viable target for future cardiovascular treatments.

For now, the failure of pelacarsen to meet its primary clinical objective has slowed expectations surrounding a potentially new category of heart medicines. However, the continuing work by several pharmaceutical companies suggests that research into inherited cholesterol-related cardiovascular risk remains an important area of medical development.

The central question facing researchers is no longer simply whether Lp(a) levels can be reduced substantially, but whether doing so can ultimately prevent serious heart disease and improve long-term patient outcomes.