In the ongoing weight loss drug arms race, Eli Lilly has taken a major step forward by releasing Phase 2 data that indicated its investigational drug cut weight by 24%.

The study results, published late Monday afternoon in the New England Journal of Medicine, found that retatrutide achieved its primary endpoint of 17.5% mean weight loss at 24 weeks in adults with obesity or who are overweight.

The next-generation molecule also achieved weight loss of 24% at 48 weeks, Lilly unveiled at the American Diabetes Association’s 83rd Scientific Sessions.

Lilly stated that retatrutide has a similar safety profile to other incretin-based therapies, while gastrointestinal side effects were generally the most common adverse symptoms and were typically mild-to-moderate in severity. 

Looking ahead, the pharma giant plans to advance retatrutide to phase 3 trials, noting that the study treating obesity and its complications. The company’s stock was trading up Tuesday morning in light of the promising announcement.

“We believe that combining glucagon receptor agonism with GIP and glucagon-like peptide 1 (GLP-1) receptor agonism may be one of the reasons retatrutide showed this level of weight reduction,” said Dan Skovronsky, MD, PhD, Lilly’s chief scientific and medical officer, and president of Lilly Research Laboratories, in a statement

Lilly is actively competing with other large drugmakers in the increasingly lucrative and widely-watched weight loss, obesity and GLP-1 space.

The company already made a splash with Mounjaro, a type 2 diabetes drug approved by the Food and Drug Administration last year that has taken off in popularity, notching more than $500 million in first quarter sales and on pace for $3.7 billion for the full year.

Lilly even launched a 75-second TV spot as part of a full-scale consumer campaign that debuted on the same day as Super Bowl LVII in mid-February.

Still, the drug has been marked by widespread off-label use for weight loss, which resulted in a two-month shortage lasting from the end of last year into this year. 

Mounjaro isn’t alone in this camp: Novo Nordisk’s injectables Wegovy and Ozempic have also been plagued by demand issues, leading the company to revise its availability and sue imposters. The FDA even weighed in earlier this month to warn consumers that some compounding pharmacies are crafting unauthorized versions of semaglutide, the active ingredient in both drugs.

Despite headwinds driven by off-label use and manufacturing deficiencies, this week has featured several major developments in the weight-loss competition.

In addition to Lilly’s data release, Novo stated in a recent corporate update that an oral version of its semaglutide helped patients taking the highest dose lose 15% of their body weight.

Pfizer also entered the fray, announcing Monday that its once-daily oral GLP-1 compound lotiglipron will be discontinued and that it will instead pursue opportunities with its  twice-a-day pill, danuglipron, in a late-stage trial.