Novo Nordisk shares fell 9.18% to $46.85 after the company announced that its ZEUS cardiovascular trial did not meet its primary endpoint of reducing major adverse cardiac events. The result raised questions about the clinical potential of ziltivekimab, an anti-IL-6 drug Novo Nordisk acquired through its 2020 purchase of Corvidia Therapeutics in a deal worth up to $725 million. Ziltivekimab had been viewed as a key pipeline asset for Novo Nordisk as the company seeks to diversify beyond its GLP-1 franchise led by semaglutide (Wegovy, Ozempic), which accounts for the bulk of its revenue. The drug showed clear biological effects on inflammation markers linked to heart and kidney disease. Novo Nordisk said the outcome will not affect its adjusted operating profit forecast for the full 2026 fiscal year.

Novo Nordisk A/S, NVO

ZEUS Study Misses Primary Cardiovascular Goal

Novo Nordisk enrolled more than 6,300 participants with established cardiovascular disease, chronic kidney disease, and elevated systemic inflammation in its phase 3 ZEUS study. The randomized, double-blind trial tested a monthly 15-milligram dose of ziltivekimab against placebo over an extended follow-up period. The primary composite endpoint included cardiovascular death, non-fatal myocardial infarction, and non-fatal stroke.

The treatment lowered levels of free interleukin-6 and high-sensitivity C-reactive protein, indicating strong activity against the intended biological targets. However, despite these anti-inflammatory effects, ziltivekimab did not deliver a statistically significant reduction in major adverse cardiovascular events versus placebo. The trial produced a hazard ratio of 0.99, with a 95% confidence interval of 0.88 to 1.11. The ZEUS outcome underscores a broader challenge in cardiovascular inflammation research: translating measurable reductions in inflammatory biomarkers into meaningful improvements in hard clinical endpoints. The IL-6 signaling pathway has been an active target in cardiology, but prior trials targeting upstream components of the same inflammatory cascade, including Novartis's CANTOS study of the anti-IL-1β antibody canakinumab, have yielded mixed cardiovascular results.

Safety findings showed that general adverse events and serious adverse events occurred at similar rates in both groups. At the same time, the ziltivekimab arm recorded more serious infections, an outcome consistent with the known immune effects of blocking the IL-6 signaling pathway. All-cause mortality was not meaningfully different between the treatment and placebo groups during the study.

Novo Nordisk Keeps Two Other Cardiovascular Trials on Track

Despite the setback in ZEUS, Novo Nordisk said it will continue with two other cardiovascular outcome trials of ziltivekimab. The HERMES trial is evaluating the drug in patients with established heart failure who remain at elevated cardiovascular risk. The ARTEMIS study is examining ziltivekimab in people who recently suffered an acute myocardial infarction and continue to face cardiovascular complications.

The company expects top-line results from both trials in the first half of 2027, according to its updated clinical development schedule. Novo Nordisk said the studies focus on different patient populations and disease settings, which could produce efficacy results different from those seen in the ZEUS cohort. The company said it will use the additional data before making final strategic decisions on ziltivekimab's commercial path.

Novo Nordisk also said the failed ZEUS trial will lead to a non-cash impairment expense in the third quarter of fiscal 2026. Even so, it confirmed that the accounting charge will not require any change to its previously communicated adjusted operating profit outlook for the full year.

The sharp share decline reflected investor concern about the reduced commercial potential of the company's cardiovascular pipeline after the study missed its main objective.