The owner of Wegovy and Ozempic has suffered a significant setback, as its highly anticipated new weight-loss treatment was labelled “obsolete” after disappointing clinical trials.

Novo Nordisk’s shares fell sharply on Monday after the results from testing the Danish company’s CagriSema drug fell short of investors’ expectations.

The weekly injection combines an amylin analogue with GLP-1 to regulate the metabolism, suppressing appetite and making users feel full more quickly. This means CagriSema leads to greater weight loss than Novo’s hugely popular Wegovy and Ozempic GLP-1 jabs.

The study was designed to show that CagriSema is at least as good as the Novo rival Eli Lilly’s leading anti-obesity drug Zepbound, which contains tirzepatide.

Against initial expectations of 25% weight loss, CagriSema disappointed in a late-state study involving 809 people. It led to average weight loss of 23% after 84 weeks if all people adhered to treatment, compared with 25.5% for tirzepatide.

The new Novo treatment “did not achieve its primary endpoint of demonstrating non-inferiority on weight loss for CagriSema compared to tirzepatide after 84 weeks”, the company said on Monday.

Søren Løntoft Hansen, a senior analyst at AL Sydbank, told Marketwire: “This is something of a swing and a miss.” He added: “It is difficult to assess whether this data will influence Novo Nordisk’s decision to launch CagriSema on the market.”

Novo’s share price plunged 16% on the news, taking its losses over the past year to almost 60%, while Lilly’s stock rose by more than 3% in pre-market trading.

Novo, which had recorded booming sales of weight-loss and diabetes medications, turning it into Europe’s most valuable company in recent years, has slashed its profit and sales estimates several times, as it lost ground to Lilly. Novo had been betting on CagriSema – as well as its new Wegovy pill – to revive sales.

Analysts at UBS had already, in January, lowered their peak sales forecast for Novo’s GLP-1 drugs from $80bn (£59bn) to $75bn in 2032, after previous disappointing CagriSema trial results.

They said on Monday of the latest results: “Significant negative. An inferior result to tirzepatide was very unexpected.”

Emmanuel Papadakis at Deutsche Bank told Novo management on an investor call: “Commiserations on the results. CagriSema looks somewhat obsolete now as a competitive upgrade of semaglutide … or as a competitive alternative to tirzepatide.”

The Novo chief executive, Mike Doustdar, rejected the comments, saying: “It’s quite belittling; it’s a fantastic drug in all honesty. When CagriSema will make it to the market early next year as the first amylin-based product, it will have the best weight-loss label [of] any marketed product.”

Novo hopes that another trial of a higher CagriSema dose will show better results. It has already submitted the medication to the US drug regulator for approval based on earlier trial evidence, and hopes for the green light later this year.