Novo Nordisk ZEUS trial fails to cut cardiovascular events
Novo Nordisk has reported that ziltivekimab, its investigational IL-6-targeting monoclonal antibody, failed to reduce major adverse cardiovascular events (MACE) in the Phase 3 ZEUS trial, despite producing the expected biological response. The headline hazard ratio of 0.99 (95% CI: 0.88 to 1.11) versus placebo represents a near-identical outcome in both arms, a result the Danish pharmaceutical giant acknowledged will require a non-cash impairment charge in the third quarter of 2026.
The ZEUS study enrolled more than 6,300 people with atherosclerotic cardiovascular disease (ASCVD), chronic kidney disease (CKD) and elevated cardiovascular inflammation, measured by high-sensitivity C-reactive protein (hsCRP) levels at or above 2 mg/L. Participants received either once-monthly subcutaneous ziltivekimab 15 mg or placebo on top of standard of care. The primary endpoint was time to first occurrence of three-point MACE, defined as cardiovascular death, non-fatal heart attack or non-fatal stroke.
What the biology showed
Ziltivekimab did achieve meaningful target engagement. The drug reduced circulating free IL-6 and suppressed hsCRP as anticipated, confirming that the molecule was doing what it was designed to do at the pathway level. The failure was one of translation: reducing IL-6-driven inflammation in this population did not convert into fewer clinical events. Rates of adverse events and serious adverse events were broadly comparable between active and placebo arms, though serious infections were more frequent with ziltivekimab, consistent with IL-6 inhibition dampening immune surveillance. No difference in all-cause mortality was observed.
Martin Holst Lange, Novo Nordisk's executive vice president and chief scientific officer, said: "While ziltivekimab did not achieve the MACE benefit we had hoped for, this does not change our strategic commitment to cardiovascular disease. The study provides important scientific evidence that will inform our ongoing cardiovascular research."
Market and competitive context
The ZEUS failure lands in a complex context for the anti-inflammatory cardiovascular field. The CANTOS trial (canakinumab, anti-IL-1beta) demonstrated proof of concept for targeting residual inflammatory risk in ASCVD in 2017, and canakinumab's MACE benefit encouraged a broader wave of cardiovascular inflammation programmes. Ziltivekimab was positioned as a more convenient, monthly subcutaneous option acting one step downstream via IL-6. The null result raises questions about whether IL-6 specifically is the right node for MACE reduction in this patient population, or whether the CKD-enriched cohort, known to have multiple competing cardiovascular risk pathways, diluted any inflammation-driven signal.
Novo Nordisk said the ZEUS outcome will not alter its adjusted operating profit guidance for 2026, suggesting the programme's financial contribution had already been discounted conservatively. The company is pressing ahead with two further ziltivekimab cardiovascular outcomes studies: HERMES, investigating the antibody in heart failure, and ARTEMIS, which examines outcomes following acute myocardial infarction. Both are expected to read out in the first half of 2027. Investors and analysts will scrutinise whether the mechanistic logic holds better in those indications, where the inflammatory contribution to disease progression may be more discrete and measurable.
The cardiovascular biologics space remains competitive. AstraZeneca's MACE-outcomes work and a number of academic and spinout programmes targeting residual inflammatory risk mean any positive signal from HERMES or ARTEMIS would re-energise the category. Full ZEUS data will be presented at a scientific meeting later in 2026, at which point a more granular subgroup analysis may reveal whether any patient segment derived benefit.