Patients on Eli Lilly's (LLY.N) weight-loss drug Zepbound substantially regained weight nearly a year after stopping treatment, according to full results of a study published on Monday.
The data, published in the journal JAMA, showed patients who were obese and without diabetes experienced a 14% weight regain nearly a year after they switched to a placebo from an eight-month course of Lilly's Zepbound.
Meanwhile, those who continued the treatment experienced an additional 5.5% weight reduction during the 52-week period, data from the study showed.
Shares of Eli Lilly fell over 4% in morning trading.
Lilly's tirzepatide is sold under brand name Zepbound for weight loss and has been available as Mounjaro for type 2 diabetes.
The drugs, along with Novo Nordisk's (NOVOb.CO) Wegovy and Ozempic, belong to a class of obesity and weight loss treatments that target the GLP-1 hormone which triggers the feeling of fullness in the body after eating.
Patients discontinuing the use of weight-loss drugs such as Wegovy risk regaining their original body weight in about five years, a Novo Nordisk official said in March.
Lilly had published some details from the trial in July.
Analysts had said, at the time, the results showed patients need to continue therapy with GLP-1 drugs for a longer term.
"We await additional longer-term data to assess the effects of tirzepatide and other incretin-based therapies after multiple years of continuous therapy," where there is a risk of rapidly diminishing response to such drugs, Goldman Sachs analysts had said in July.
Over the course of the entire treatment period of 88 weeks, patients who continued Lilly's drug showed 25.3% weight loss. The overall weight reduction was 9.9% during the entire study period for patients who switched to placebo after 56 weeks.
