SAN DIEGO – New designer molecules that target weight loss via multiple mechanisms continue to raise the bar of how many pounds people with overweight or obesity can lose.
Retatrutide (Eli Lilly), an investigational agent that combines agonism to three key hormones that influence eating and metabolism into a single molecule, safely produced weight loss at levels never seen before in a pair of phase 2 studies that together randomized more than 600 people with overweight or obesity, with or without type 2 diabetes.
Among 338 randomized people with overweight or obesity and no type 2 diabetes,
Among 281 randomized people with overweight or obesity and type 2 diabetes, the same dose of retatrutide produced a nearly 17% cut in weight from baseline after 36 weeks of treatment.
Never before seen weight loss
“I have never seen weight loss at this level” after nearly 1 year of treatment, Ania M. Jastreboff, MD, PhD, who led the obesity study, said during a press briefing at the annual scientific sessions of the American Diabetes Association.
The average weight loss by study participants taking high-dose retatrutide in the two studies “is really impressive, way beyond my wildest dreams,” said Carel le Roux, MBChB, PhD, an obesity and diabetes researcher at University College Dublin, Ireland, who was not involved with the retatrutide studies.
And Robert A. Gabbay, MD, chief scientific and medical officer of the ADA, called the results “stunning,” and added, “we are now witnessing the first triple-hormone combination being highly effective for not only weight loss but liver disease and diabetes.”
A prespecified subgroup analysis of the obesity study showed that at both 8-mg and 12-mg weekly doses, 24 weeks of retatrutide produced complete resolution of excess liver fat (hepatic steatosis) in about 80% of the people eligible for the analysis (those with at least 10% of their liver volume as fat at study entry); that figure increased to about 90% of people on these doses after 48 weeks, Lee M. Kaplan, MD, reported during a separate presentation at the meeting.
Adding glucagon agonism ups liver-fat clearance
“When you add glucagon activity,” one of the three agonist actions of retatrutide, “liver-fat clearance goes up tremendously,” said Dr. Kaplan, director of the Obesity, Metabolism and Nutrition Institute at Massachusetts General Hospital in Boston.
“To my knowledge, no mono-agonist of the glucagon-like peptide-1 (GLP-1) receptor [such as semaglutide or liraglutide] produces more than 50% clearance of liver fat,” added Dr. Kaplan.
The separate, randomized study of people with type 2 diabetes showed that in addition to producing an unprecedented average level of weight loss at the highest retatrutide dose, the agent also produced an average reduction from baseline levels of A1c of about 2 percentage points, an efficacy roughly comparable to maximum doses of the most potent GLP-1 mono-agonist semaglutide (Ozempic, Novo Nordisk), as well as by tirzepatide (Mounjaro, Eli Lilly), a dual agonist for the GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) receptors.
“No other medication has shown an average 17% reduction from baseline bodyweight after 36 weeks in people with type 2 diabetes,” said Julio Rosenstock, MD, director of the Dallas Diabetes Research Center at Medical City, Texas, who presented the results from the type 2 diabetes study of retatrutide.
For the obesity study, people with a body mass index of 27-50 kg/m2 and no diabetes were randomized to placebo or any of four retatrutide target dosages using specified dose-escalation protocols. Participants were an average of 48 years old, and by design, 52% were men. (The study sought to enroll roughly equal numbers of men and women.) Average BMI at study entry was 37 kg/m2.
Weight loss levels after 24 and 48 weeks of retatrutide treatment followed a clear dose-related pattern. (Weight loss averaged about 2% among the 70 controls who received placebo.)