The global phase 3 clinical trial known as ZEUS has challenged long-standing assumptions about cardiovascular medicine by revealing that targeting the interleukin-6 inflammatory pathway with ziltivekimab did not reduce major cardiovascular events compared to placebo.
Led by Mass General Brigham researcher Paul Ridker, MD, the late-breaking findings were presented at the American Heart Association Scientific Session and published simultaneously in the New England Journal of Medicine. While the monoclonal antibody successfully lowered interleukin-6 levels, it failed to alter rates of heart attack, stroke, or cardiovascular death in the trial population.
- What happened: A new anti-inflammatory drug designed to lower heart risks successfully reduced inflammation markers but did not lower actual heart attack or stroke rates in this specific study.
- Why it matters: Inflammation causes cardiovascular disease just like cholesterol does, but finding the exact molecular target to treat it safely remains complex.
- What patients should do: Proven preventive measures—such as diet, exercise, smoking cessation, statins, and low-dose colchicine—remain vital for managing inflammation and protecting heart health.
Like the earlier Canakinumab Anti-inflammatory Thrombosis Outcomes Study (CANTOS), the Ziltivekimab Cardiovascular Outcomes Study (ZEUS) enrolled patients with atherosclerotic cardiovascular disease and systemic inflammation. However, the demographic profile of ZEUS participants differed significantly from its predecessor. Sponsored by Novo Nordisk, ZEUS enrolled individuals who were a decade older, lived with significant kidney disease, and frequently managed longstanding diabetes and heart failure.
“In people with non-modifiable disease, the horse may already have been out of the barn,” Ridker noted regarding the study population. The primary endpoint—a composite of heart attack, stroke, or cardiovascular death—occurred in 561 participants in the ziltivekimab treatment group compared to 565 in the placebo group. Safety profiles showed no adverse effect on total mortality, though researchers recorded a small increase in infection rates.
Researchers are now looking upstream to target alternative inflammatory drivers, such as the NLRP3 inflammasome, while acknowledging that downstream interleukin-6 inhibition might still prove effective if applied to younger patient populations with earlier-stage disease. “Given our neutral findings, one logical next step is to move upstream, instead of downstream, to find the right target,” Ridker explained.
At the same time, existing clinical options remain underutilized. For patients with stable atherosclerotic disease, the LoDoCo2 and COLCOT trials previously demonstrated that the generic drug colchicine significantly reduces cardiovascular event rates. Low-dose colchicine holds US Food and Drug Administration approval for lowering heart attack and stroke risks through anti-inflammatory mechanisms.
“What ZEUS shows us is that this particular drug in this particular setting didn’t work,” Ridker stated. “But it’s important to remember that we have other proven anti-inflammatory drugs such as low-dose colchicine that are being underutilized today in our patients with stable atherosclerosis.”
Clinicians should evaluate systemic inflammatory risk using inexpensive blood tests like high-sensitivity C-reactive protein (hsCRP), as recommended by recent American College of Cardiology guidelines.
Standard preventive pillars—including smoking cessation, structured exercise, and medical management with statins or GLP-1 receptor agonists—continue to provide proven anti-inflammatory and cardioprotective benefits. Physicians must actively measure inflammatory markers to tailor these interventions effectively.
- Ridker, P. M., et al. (2026). Interleukin-6 inhibition with ziltivekimab for atherosclerotic disease. New England Journal of Medicine. DOI: 10.1056/nejmoa2612126
- American Heart Association Scientific Session. Late-Breaking Clinical Trials.
- US Food and Drug Administration (FDA). Approved Anti-Inflammatory Cardiovascular Therapeutics.
