Eli Lilly today released results from its phase 3 ATTAIN-1 trial, which was evaluating the use of its oral GLP-1 receptor agonist (GLP-1RA) for the treatment of patients with obesity. In essence, the goal of this late-stage study was to see if an oral version of this class of drugs could attain equal or better weight loss compared to GLP-1 injectables. This was a very large study because it recruited a total of 3,127 adults and randomized them to either take orforglipron or a placebo for a total of 72 weeks. The good thing about this data release is that all of the doses tested of this drug in this late-stage trial achieved the primary endpoint compared to placebo.
In essence, patients were evaluated for average weight loss percentage from baseline, and such a measure compared whether all doses of orforglipron or a placebo did better in this regard. The thing is that it was not likely that placebo was going to beat orforglipron, but the problem lies in the fact that after the entire study was done, the amount of weight lost did not impress Wall Street. It was noted that after patients took the highest dose of once-daily oral GLP-1RA, 36 mg, they attained an average weight loss of 12.4%. This translates to a median weight loss of 27.3 lbs. Not to say exactly that the data is terrible, because it still met the primary endpoint for starters. In addition, the results that were obtained are definitely going to be enough to allow Eli Lilly to file for regulatory approval of it to treat these patients with obesity.
The issue comes whereby it was hoped that the oral drug would be able to best injectable GLP-1 drugs that are currently available for starters. Truthfully, the hope was that orforglipron would be able to achieve better weight loss than Novo Nordisk’s Wegovy, which is an injectable GLP-1 approved to treat obesity patients. Another downside is that analysts had hoped that Eli Lilly’s oral drug would at least allow patients to obtain an average weight loss of about 15%. This is not just some random number that is being thrown around; this space is getting crowded, and companies need to have some type of a competitive edge in place to make sure they stay on top.
With that being said, Novo Nordisk is also in the process of gunning for regulatory approval of an oral version of GLP-1 semaglutide. As a matter of fact, in a late-stage study of its own for such an oral version, it was able to show that patients obtained an average weight loss of 15%. The FDA had already accepted a regulatory application from this big pharma for the treatment of patients with obesity and is expected to make a decision on U.S. marketing approval of it in late 2025. While it is disappointing that Eli Lilly’s orforglipron didn’t meet the streets’ expectation, it is likely still expected to have some market share, being that patients would like to have an oral GLP-1 drug option.
On the other hand, where this drug also fell short in the phase 3 ATTAIN-1 study is that there were a good amount of patients who had dropped out of the study due to side effects. Thus, it could be effective in terms of weight loss for sure, but only for patients who don’t mind the side effects of it. It remains to be seen if this is going to be a hindrance going forward; of course, that is if it can convince the FDA to approve it for marketing. I don’t believe that it is time for the company to panic, though, because the obesity space is a large one. Analysts believe that the GLP-1 market could be worth $150 billion annually by the 2030s.
All is not lost for Eli Lilly, though, because it was able to beat estimates for its second-quarter 2025 earnings. The reason why is because of Zepbound and Mounjaro, which helped Eli Lilly to not only beat its earnings estimates for the quarter but to also raise its full-year 2025 revenue guidance to be $60 billion to $62 billion. Mounjaro (tirzepatide) is approved to treat patients with T2D with diet and exercise, and then Zepbound (tirzepatide) is approved to treat patients with obesity along with diet and exercise. Both drugs had impressive revenue growth, but the true star, I would say, was Zepbound, which brought in $3.38 billion in sales for Q2 of 2025. Having said that, this was a year-over-year revenue growth of 172%.