Novo Nordisk (NYSE:NVO) shares tumbled Monday morning after the Danish drugmaker announced that its highly anticipated obesity treatment, CagriSema, failed to achieve non-inferiority against Eli Lilly’s (NYSE:LLY) blockbuster tirzepatide in a head-to-head Phase 3 trial.
The setback marks a pivotal moment in the battle for dominance within the global weight-loss market, as Novo struggles to match the efficacy benchmarks set by its primary rival.
In the REDEFINE 4 open-label trial, which followed 809 participants over 84 weeks, CagriSema—a combination of the GLP-1 semaglutide and the long-acting amylin analogue cagrilintide—achieved a 23% mean reduction in body weight.
While clinically significant, it fell short of the 25.5% reduction demonstrated by tirzepatide (marketed as Zepbound and Mounjaro).
When applying the "treatment-regimen" estimand, which accounts for participants who discontinued therapy, CagriSema’s weight loss dropped to 20.2% versus 23.6% for Lilly’s drug.
The market reaction was swift and severe.
Novo Nordisk’s Copenhagen-listed shares plunged 11% by mid-morning, erasing billions in market capitalization.
Conversely, Eli Lilly shares climbed 4.2% in U.S. premarket trading, extending the company’s lead as the most valuable pharmaceutical firm in the world.
Analysts noted that the failure to meet the non-inferiority goal erodes the "next-generation" narrative for CagriSema, which Novo had positioned as its premier response to tirzepatide's superior weight-loss profile.
Despite the top-line miss, Novo Nordisk emphasized that CagriSema maintained a "safe and well-tolerated profile" consistent with the GLP-1 class, primarily characterized by mild-to-moderate gastrointestinal events.
The company remains committed to the asset, with regulatory filings already submitted to the U.S. FDA in December 2025.
Novo also confirmed it will initiate new trials in the second half of 2026 to explore higher-dose combinations of CagriSema, aiming to push weight-loss efficacy closer to the 30% threshold currently targeted by Lilly’s investigative "triple G" drug, retatrutide.
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