TORONTO– Eli Lilly Canada today announced topline results from the SURMOUNT-5 Phase 3b open-label randomized clinical trial. Tirzepatide provided a 47% greater relative weight loss compared to Wegovy® (semaglutide). On average, tirzepatide led to a superior weight loss of 20.2% compared to 13.7% with Wegovy. At 72 weeks, tirzepatide was superior to Wegovy on both the primary endpoint and all five key secondary endpoints in this trial of adults living with obesity or overweight with at least one weight-related medical problem and without diabetes.
“This study demonstrated that at maximum tolerated dose tirzepatide was superior to semaglutide 2.4 mg in a head-to-head trial,” says Dr. Sean Wharton, an internal medicine physician, assistant professor at the University of Toronto and the lead author of the Canadian Obesity Guidelines. “We now understand that obesity is not a lack of will power, but a medical condition that can be treated with lifestyle modification along with medical interventions, and that can include pharmacotherapy. This research advances the field of obesity medicine and gives patients greater options to treat this chronic condition.”
In addition, in a key secondary endpoint, 31.6% of people taking tirzepatide achieved at least 25% body weight loss compared to 16.1% of those taking Wegovy.
“The head-to-head results of SURMOUNT-5 demonstrate the power of tirzepatide with a statistically significant, clinically meaningful difference in weight loss compared to semaglutide,” says Kenneth Custer, Lilly Canada President, and General Manager. “Lilly Canada is excited about the potential for tirzepatide to improve outcomes for people living with obesity.”
The overall safety profile of tirzepatide in SURMOUNT-5 was similar to previously reported SURMOUNT trials. The most commonly reported adverse events in SURMOUNT-5 for both tirzepatide and Wegovy were gastrointestinal-related and were generally mild to moderate in severity. This trial was not designed to examine differences in adverse events between tirzepatide and Wegovy.
Lilly will continue to evaluate the SURMOUNT-5 results, which will be published in a peer-reviewed journal and presented at a medical congress next year. Tirzepatide is approved in Canada under the brand name Mounjaro for type 2 diabetes. Tirzepatide is not currently approved by Health Canada for chronic weight management.