Novo Nordisk's Ziltivekimab Fails Phase 3 ZEUS Trial, Missing Primary MACE Endpoint in Cardiovascular Disease
Key Insights
Novo Nordisk's IL-6 inhibitor ziltivekimab failed to reduce major adverse cardiovascular events (MACE) versus placebo in the Phase 3 ZEUS trial, with a hazard ratio of 0.99 (95% CI: 0.88–1.11).
The trial enrolled over 6,300 patients with atherosclerotic cardiovascular disease (search), chronic kidney disease (search), and elevated inflammation, testing once-monthly ziltivekimab on top of standard care.
While ziltivekimab produced the expected biological effect by reducing IL-6 and hs-CRP levels, this did not translate into clinical benefit; serious infections occurred more frequently in the ziltivekimab arm.
Novo Nordisk announced Friday that its experimental heart drug ziltivekimab failed to meet its primary endpoint in the Phase 3 ZEUS trial, dealing another setback to the Danish drugmaker's pipeline and sending shares down as much as 10% in Copenhagen trading. The once-monthly injectable, designed to block the IL-6 inflammatory pathway, did not produce a statistically meaningful reduction in major adverse cardiovascular events (MACE) compared with placebo on top of standard care.
The ZEUS trial enrolled more than 6,300 people with atherosclerotic cardiovascular disease (search), chronic kidney disease (search), and elevated inflammation. MACE was defined as a composite of cardiovascular death, non-fatal heart attack, or non-fatal stroke. The hazard ratio came in at 0.99, with a 95% confidence interval of 0.88 to 1.11, indicating no meaningful risk reduction.
"While ziltivekimab did not achieve the MACE benefit we had hoped for, this does not change our strategic commitment to cardiovascular disease," said Martin Holst Lange, executive vice president, chief scientific officer, and head of Research and Development at Novo Nordisk.
Biological Effect Without Clinical Translation
Ziltivekimab did produce the expected biological effect — reducing free IL-6 and high-sensitivity C-reactive protein (hs-CRP) levels — but that pharmacodynamic activity did not translate into clinical benefit. "Although ziltivekimab produced the expected biological effect, this did not result in MACE benefits in this population," Lange said. "The study provides important scientific evidence that will inform our ongoing cardiovascular research."
The safety profile showed broadly comparable adverse-event rates across both arms of the trial, with one notable exception: serious infections occurred more frequently in patients who received ziltivekimab. Deaths from any cause occurred at similar rates in both groups, the company reported.
Market Reaction and Pipeline Implications
Copenhagen-listed Novo Nordisk shares fell as much as 10% on Friday, while American depositary receipts were trading 8.6% lower in premarket hours — on track for their worst single-day performance since February, when the company released disappointing results from a head-to-head trial of its next-generation weight-loss drug CagriSema versus Eli Lilly's rival medicine. If losses hold, shares will turn negative for the year.
Jefferies and Citi analysts both characterized the share move as disproportionate given ziltivekimab's small contribution to Novo's overall portfolio. However, Jefferies noted that "the result is strategically negative as it removes one of Novo's more credible non-obesity growth opportunities and again reinforces the company's reliance on commercial execution in obesity and sourcing external innovation for driving growth."
Financial Impact and Ongoing Trials
The trial result will not affect the company's adjusted operating profit outlook for 2026, but Novo Nordisk said it will record a non-cash impairment charge in the third quarter. Two other cardiovascular trials testing ziltivekimab are continuing: the HERMES trial in heart failure patients and the ARTEMIS trial in patients following an acute heart attack. Both are expected to produce results in the first half of 2027.
Full results from the ZEUS trial will be presented at a scientific meeting later in 2026.
The ZEUS failure adds to a difficult stretch for Novo Nordisk, which has been working to restore investor confidence in its pipeline and commercial execution, particularly in the challenging U.S. market. The company raised its full-year guidance in May after first-quarter sales of its Wegovy weight loss pill exceeded expectations, offering a measure of relief after Copenhagen-listed shares had shed roughly 40% of their value over the prior year. Heading into Friday's session, the stock had declined 7% year-to-date.