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.