Lilly Stock Slips as Patients Regain Weight After Stopping Zepbound

Pictured: an Eli Lilly building in San Diego/iStock, JHVE Photo

Eli Lilly’s stock slipped 4% in premarket trading Monday after a study published in the scientific journal JAMA found patients on its weight loss drug regained “substantial” weight after stopping treatment.

Lilly’s terzepatide, sold under the brand name Zepbound for weight loss and Mounjaro for type 2 diabetes, is a glucagon-like peptide 1 (GLP-1) receptor agonist. Drugs targeting the GLP-1 hormone, which regulates the feeling of fullness in the body, have become wildly popular in the weight loss space.

The JAMA study found that patients taking Zepbound lost an average of 20.9% of their weight over 36 weeks. Those who then switched to a placebo saw on average a 14% weight gain over the next 52 weeks. Patients who remained on the therapy lost an additional 5.5% weight over the same 52-week period. In total over 88 weeks, patients who remained on Zepbound lost 25.3% of their body weight, while those who switched to placebo lost 9.9%.

Shares of Eli Lilly fell 4% in premarket trading Monday.

The results are not inconsistent with findings from other GLP-1 receptor agonists. An official with Novo Nordisk, which produces semaglutide—marketed as Wegovy for weight loss and Ozempic for type 2 diabetes—noted in March that patients discontinuing drugs like Wegovy risk regaining their original weight within five years. A 2022 study on semaglutide suggested patients regained two-thirds of the weight they lost on the drug after being off of it for a year.

Nor do the findings come fully as a surprise to Lilly. Preliminary results from July suggested a need for long-term treatment, according to Goldman Sachs analysts, Reuters reported. At the time, analysts noted they were awaiting “additional longer-term data to assess the effects of tirzepatide and other incretin-based therapies after multiple years of continuous therapy.”

The JAMA study’s authors noted that there were limitations to their findings, including that the design did not allow for dose adjustments after randomization, and the effects of intensive behavioral therapy on the maintenance of weight loss were not evaluated.

The FDA approved Zepbound for weight loss in November based on Phase III results that found the drug, used in concert with exercise and diet modifications, resulted in average weight loss of 48 lbs at the highest dose, and 34 lbs at the lowest dose, compared to 7 lbs for those on placebo.

A comparative analysis of terzepatide and semaglutide based on electronic health records by healthcare data and analytics firm Truveta Research suggested the former might be a better option for overweight and obese patients, with patients on tirzepatide being three times as likely to lose 15% of their body weight, in addition to achieving faster weight loss.

Connor Lynch is a freelance writer based in Ottawa, Canada. Reach him at lynchjourno@gmail.com.