Novo Nordisk's Failed Heart Drug Trial Deepens a Season of Setbacks

Novo Nordisk's heart drug Ziltivekimab misses primary endpoint in phase 3, wiping $30B off market cap and raising doubts on pipeline beyond obesity.

The Danish pharmaceutical giant's pipeline ambitions beyond its blockbuster weight-loss franchise suffered a serious blow on Friday, as the phase 3 ZEUS trial for the cardiovascular candidate Ziltivekimab failed to hit its primary endpoint. Shares in the Copenhagen-based company closed the session at EUR 40.90 in German trading, down 8.48% — the steepest single-day decline in nearly five months.

The stock now sits 25.45% below its 52-week high of EUR 54.86, reached on January 23. Yet the damage over a full year appears more contained than the recent turbulence might suggest: the equity is down just 0.86% on a twelve-month basis, a reflection of how sharply the shares have swung in both directions during that period.

A Biologically Active Drug That Failed to Deliver

The ZEUS study enrolled more than 6,300 patients with atherosclerotic cardiovascular disease, chronic kidney disease, and elevated inflammatory markers (hsCRP of at least 2 mg/l). Participants received monthly 15-milligram doses of the antibody. While Ziltivekimab reduced the inflammatory biomarkers interleukin-6 and hsCRP as expected, it produced no meaningful reduction in the composite of cardiovascular death, non-fatal heart attack, or stroke compared with placebo — the hazard ratio came in at 0.99, effectively a null result.

The profile was further complicated by safety signals: serious infections occurred more frequently in the treatment arm, while overall mortality showed no difference between groups. The drug's origins trace back to Novo Nordisk's 2020 acquisition of Corvidia Therapeutics for USD 725 million, a deal that carried the potential for an additional USD 2.1 billion in milestone payments.

The company has signalled a non-cash impairment charge for the third quarter, though management insists the full-year 2026 guidance remains unaffected. Martin Holst Lange, chief scientific officer, told CNBC the outcome does not alter the company's strategic commitment to cardiology. Two further studies of the drug — HERMES, examining Ziltivekimab in heart failure, and ARTEMIS, in acute myocardial infarction — remain ongoing, with results expected in the first half of 2027 that could determine whether the cardiovascular program can be salvaged.

Analysts Split on the Market's Reaction

Jefferies and Citi both characterised Friday's sell-off as excessive, while conceding the trial failure carries strategic significance. The drug was meant to provide Novo Nordisk with a credible growth engine beyond its obesity and diabetes franchises — an option that has now evaporated, at least for the foreseeable future. The consensus analyst rating sits at "Hold" with a price target near USD 47.

The market's verdict was stark: roughly USD 30 billion in market capitalisation was erased on Friday. Critics of the sell-off argue that figure bears little relation to the drug's actual revenue contribution, while sceptics point to the company's heavy reliance on the GLP-1 portfolio — Ozempic and Wegovy — as a structural vulnerability that the ZEUS failure has thrown into sharper relief.

The shockwaves rippled beyond Novo Nordisk itself. Monte Rosa Therapeutics, a biotech focused on inflammation programs, saw its shares tumble 27.5% as investors reassessed the entire anti-inflammatory drug class in light of the ZEUS outcome.

A Cascade of Disappointments

The ZEUS failure did not arrive in isolation. Shortly beforehand, a study of a semaglutide pill for Alzheimer's disease had also come up short. And in the REDEFINE-1 trial, the weight loss achieved with the combination therapy CagriSema — 22.7% — fell short of the company's internal target of 25%. These setbacks prompted Novo Nordisk to slash its revenue growth guidance for the current year to a range of 8% to 14%, having previously signalled growth of up to 21%. For 2026, the company now anticipates a decline in both revenue and operating profit of as much as 13% on a currency-adjusted basis.

Legal Pressures From Both Directions

The clinical disappointments are compounded by legal entanglements. On July 28, a US federal judge ruled that Novo Nordisk must face part of a shareholder lawsuit alleging the company misled investors about CagriSema's tolerability in the REDEFINE-1 study. Other claims were dismissed, and Novo Nordisk denies the remaining allegations.

The company is also playing offence in the courts. On July 21, it filed a lawsuit against Eli Lilly over allegedly misleading advertising for Lilly's GLP-1 products, with a hearing scheduled for August 27.

What to Watch on August 5

Investors now turn their attention to the second-quarter results, due on August 5. Analysts expect revenue of DKK 71.5 billion, down from DKK 76.9 billion in the same period last year, with earnings per share of DKK 5.04 versus DKK 5.96 previously. One set of forecasts puts EPS at USD 0.81, a 16.5% decline year on year.

The share buyback program continues in parallel: as of July 24, Novo Nordisk had deployed approximately USD 1.1 billion of the up to USD 2.3 billion authorised under the current scheme.

There have been bright spots on the regulatory front. On July 15, the oral Wegovy pill received EU approval, alongside a higher-dose 7.2-milligram version of the drug. Whether those wins can restore investor confidence after such a concentrated run of setbacks will likely hinge on what the earnings report reveals about the resilience of the core GLP-1 business — and whether the ZEUS disappointment is a one-off stumble or a sign of deeper cracks in the company's growth story.