It was a rough Monday for Novo Nordisk A/S (NVO). The company's stock took a dive, hitting its lowest point in a year, and the reason is a story of high-stakes pharmaceutical competition. The latest data from a crucial clinical trial showed its next-generation weight-loss hopeful, CagriSema, didn't quite measure up against the current champ from Eli Lilly and Co. (LLY).

This wasn't just any study. It was part of Novo's big REDEFINE program, specifically trial number 4. They put their drug, a combo of cagrilintide and semaglutide, head-to-head against Lilly's tirzepatide (sold as Zepbound and Mounjaro) in over 800 people with obesity for 84 weeks. When the numbers came in, they told a clear, if disappointing, story for Novo.

How the Numbers Shook Out

Let's talk results. When you look at the data assuming everyone stuck perfectly to their treatment, people on CagriSema lost 23.0% of their body weight after 84 weeks. That's impressive, but Lilly's tirzepatide group did even better, shedding 25.5%. The more realistic analysis, which accounts for how people actually use medicines in the real world, showed a similar gap: 20.2% weight loss for CagriSema versus 23.6% for tirzepatide.

Here's the kicker: the main goal of this trial was to prove that CagriSema was at least as good as (or "non-inferior" to) tirzepatide. On that critical measure, the trial did not succeed. It's a clear win for Lilly's drug in this direct comparison. On the safety side, things looked more standard; CagriSema's side effects were mostly gastrointestinal, mild to moderate, and faded over time—pretty typical for this class of GLP-1 drugs.

What's Next for Novo's Contender?

So, is this the end for CagriSema? Not according to Novo Nordisk. Martin Holst Lange, the company's head of R&D, pointed to the future. "Based on the learnings from completed studies, we look forward to the REDEFINE 11 readout and the initiation of the higher-dose CagriSema trial, which are both designed to assess the full weight-loss potential of CagriSema," he said.

The regulatory wheels are already in motion. Novo submitted CagriSema to the FDA for weight management back in December 2025, based on earlier successful trials (REDEFINE 1 and 2). A decision from the agency is expected by late 2026. Meanwhile, the company is planning more studies: results from the REDEFINE 11 trial are due in the first half of 2027, and a new trial testing an even higher dose of CagriSema is slated to start in the second half of 2026.

It's worth noting that CagriSema isn't a total flop. Just last month, data from another trial showed it beat Novo's own blockbuster semaglutide (the active ingredient in Wegovy and Ozempic) in both blood sugar control and weight loss. But in the brutal, winner-take-all world of obesity drugs, beating your own older product isn't enough. You have to beat the other guy's best product, too.

The market's reaction was swift and severe. Novo Nordisk shares were down over 13% in premarket trading, hitting around $41.12. That drop cements a painful trend—the stock is now down about 48% over the last 12 months. It's a stark reminder of how much investor sentiment in this sector hinges on these head-to-head clinical showdowns. For now, Eli Lilly's tirzepatide remains the drug to beat.