Preliminary data from a large Phase 3 clinical trial is offering promising signs for a new anti-obesity drug. Called tirzepatide, the drug helped overweight and obese participants lose up to 22.5 percent of their total body weight over the 72-week trial.
Last year the US Food and Drug Administration (FDA) approved a drug called Wegovy (or semaglutide) as a weight management tool for obese or overweight people. Wegovy was the first of a new class of anti-obesity treatments to be approved by the FDA.
These drugs are designed to mimic the action of a naturally-occurring hormone called glucagon-like peptide-1 (GLP-1), which is produced by intestinal cells and plays a number of metabolic roles, from regulating blood-sugar levels to helping suppress appetite.
GLP-1 therapies were originally developed to treat type 1 diabetes, and Wegovy was first approved by the FDA as a diabetes treatment in 2017. But subsequent research showed the drugs can also function as effective weight-loss treatments in obese or overweight people without diabetes.
Tirzepatide follows on the heels of Wegovy, but it works slightly differently. Instead of directly acting on GLP-1 receptors, tirzepatide is a molecule designed to simultaneously mimic a slightly different hormone called gastric inhibitory polypeptide (GIP). Early studies found this novel molecule results in a dual-action on both GLP-1 and GIP receptors, leading to greater decreases in food intake and greater increases in energy expenditure.
As a treatment for diabetes tirzepatide was formally submitted to the FDA for approval late last year. Based on successful Phase 3 trial results, that approval is expected to come over the next few months.
This new data, announced in a press release from pharma company Eli Lilly and yet to be peer-reviewed or published in a journal, offers the first glimpse at the effect of tirzepatide on weight loss. And these top line results are even stronger than the results from Wegovy’s “game-changing” trial data.
The Phase 3 trial, called SURMOUNT-1, enrolled 2,539 subjects across nine countries, with the mean body weight of each participant being 231 lb (105 kg). Each participant was randomly, and blindly, put into one of four groups: tirzepatide 5 mg, 10 mg or 15 mg, or placebo. The treatment involved one sub-cutaneous injection of the drug each week.
At the end of the 72-week program those on the lowest dose had lost an average of 16 percent of their bodyweight, while those on the highest dose dropped 22.5 percent. This compared to just a 2.4-percent drop in body weight for those taking the placebo.
It is important to note the trial was not testing the effect of the drug by itself, but as an adjunct to a calorie-controlled diet and exercise program. So this isn’t a miracle drug that helps you drop weight without any other kind of intervention. But, considering the placebo group was also directed to follow the diet and exercise program it seems clear the drug therapy significantly helps a person lose weight more effectively.
The early data from this trial suggests tirzepatide is potentially more effective than Wegovy at long-term weight reduction. Around one-third of those in the Wegovy Phase 3 trial lost more than 20 percent of their body weight, whereas this preliminary data reports 20 percent weight reductions in 55 percent of the 10-mg group and 63 percent of the 15-mg group.
"Tirzepatide is the first investigational medicine to deliver more than 20 percent weight loss on average in a phase 3 study, reinforcing our confidence in its potential to help people living with obesity," said Jeff Emmick, vice president of product development at Eli Lilly. "We're proud to research and develop potentially innovative treatments like tirzepatide, which helped nearly two thirds of participants on the highest dose reduce their body weight by at least 20 percent in SURMOUNT-1."
SURMOUNT-1 is part of a larger series of six global trials looking at the effects of tirzepatide on obesity. Overall there are more than 5,000 people enrolled in the study and more results from some of the other trials are expected next year.
Source: Eli Lilly
