Eli Lilly and Company is reporting headline-grabbing results from late-stage trials of its investigational obesity drug retatrutide, a once-weekly “triple agonist” designed to target GIP, GLP-1, and glucagon receptors.

 

The approach, the global pharma powerhouse says, could reshape treatment for obesity and its related diseases.

 

In the Phase 3 TRIUMPH-1 study, patients taking the highest dose of retatrutide lost an average of 70.3 lbs (28.3%) over 80 weeks. More than 65% of participants dropped below a BMI of 30, moving out of the clinical obesity range.

 

The benefits went well beyond weight loss.

 

In addition to weight loss, retatrutide reduced knee osteoarthritis pain by up to 4.3 points (73.1%) and moderate-to-severe obstructive sleep apnea severity by up to 36.1 events per hour (60.6%).

 

A companion study in type 2 diabetes, TRANSCEND-T2D-1, showed similarly strong metabolic effects at 40 weeks:

 

In TRANSCEND-T2D-1, participants on retatrutide achieved A1C reductions of up to 2.0% and weight loss of up to 36.6 lbs (16.8%) at 40 weeks, with up to 46% achieving a normal A1C.

 

Researchers say the results point to a potential shift in how obesity is treated—as a central disease driving multiple conditions, rather than a collection of separate problems.

 

"Obesity drives more than 200 downstream diseases, yet we have historically treated those conditions one at a time and in silos," said Ania Jastreboff, Professor of Medicine & Pediatrics (Endocrinology) at the Yale School of Medicine, Director of the Yale Obesity Research Center (Y-Weight), and lead investigator. 

 

"In TRIUMPH-1 and TRANSCEND-T2D-1, treatment with retatrutide resulted in substantial weight reduction together with clinically meaningful improvements in glycemia, knee osteoarthritis pain, and obstructive sleep apnea, with many individuals reaching what are classified as healthy-range weight and normal blood sugar levels. 

 

"These findings demonstrate what may be possible when we treat obesity and impact overall health, and what this could mean for people living with obesity and its related complications."

 

Eli Lilly executives say the breadth of the results sets the drug apart.

 

"Across TRIUMPH-1 and TRANSCEND-T2D-1, retatrutide delivered substantial weight loss, meaningful A1C reduction, and improvements in knee osteoarthritis pain and moderate-to-severe obstructive sleep apnea, a breadth and magnitude of outcomes that's striking to see with a single therapy," said Kenneth Custer, executive vice president and president, Lilly Cardiometabolic Health. 

 

"By addressing weight, glycemia and obesity-related complications together, these results highlight retatrutide's potential across the cardiometabolic spectrum and reinforce our commitment to delivering options that meet patients' needs and preferences."

 

In TRIUMPH-1, participants receiving 9 mg and 12 mg doses lost 64.4 lbs (25.9%) and 70.3 lbs (28.3%), respectively, while the 4 mg group lost 47.2 lbs (19.0%). Some participants continued beyond 80 weeks, with extended treatment showing even greater losses.

 

Notably, 65.3% of participants on retatrutide 12 mg achieved a BMI <30, and 33.3% reached a BMI <25, representing healthy BMI.

 

The trial also recorded improvements in physical function and sleep apnea severity, including reductions in knee pain scores and breathing interruptions during sleep.