Novo Nordisk Heart Drug Ziltivekimab Fails Phase III Trial, Shares Plunge Over 10%

Danish pharmaceutical giant Novo Nordisk announced that its closely watched experimental heart drug, ziltivekimab, failed to meet the primary endpoint in a large late-stage clinical trial.

The trial, named Zeus, aimed to evaluate whether the monthly injectable IL-6 inhibitor, ziltivekimab, could reduce the risk of major adverse cardiovascular events (MACE) compared with a placebo on top of standard care in a specific patient population. MACE was defined as cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke.

The study enrolled more than 6,300 patients with atherosclerotic cardiovascular disease, chronic kidney disease, and elevated levels of inflammation. Results showed that although the drug effectively lowered the target protein in the body, demonstrating biological activity, this effect did not translate into a statistically significant reduction in MACE risk. On safety, the overall incidence of adverse events was similar between the two groups, but the ziltivekimab group had a higher rate of serious infections, while overall mortality showed no difference.

Novo Nordisk Chief Scientific Officer Martin Holst Lange said that while ziltivekimab failed to achieve the expected MACE benefit, this would not change the company's strategic commitment to cardiovascular disease.

Following the news, Novo Nordisk's US-listed shares fell more than 8% in premarket trading, while its Copenhagen-listed shares plunged as much as 10.5%, the largest intraday decline since February 2026. As of Thursday's close, the company's American depositary receipts (ADRs) still held a gain of 5% for the year, but its Danish-listed shares had already fallen 7% year-to-date before the announcement.