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Tirzepatide use leads to over 20% weight loss in obese patients

Study data showing how tirzepatide reduced body weight in obese or overweight patients by more than a fifth after 72 weeks has been released

Headline results from a phase 3 randomised trial by Lilly have shown that use of the anti-diabetic agent tirzepatide 15 mg for 72 weeks led to a 22.5% reduction in weight among those classed as either overweight and obese patients.

Tirzepatide is described as a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist that is in development for the treatment of type 2 diabetes. Early data from studies in mice suggested that chronic administration of the drug, could reduce both food intake and body weight and how it was suitable for administration on a weekly basis.

Moreover, studies in humans have shown the drug to be an effective treatment for patients with type 2 diabetes. For example, in randomised, double-blind phase 3 trial in patients with type 2 diabetes, tirzepatide was found to produce significantly better efficacy with regard to glucose control and weight loss than the comparator, dulaglutide.

In addition, in an open-label, 40-week trial, in 1879 patients with type 2 diabetes, tirzepatide was found to be non-inferior and superior to semaglutide with respect to the mean change in the glycated haemoglobin level from baseline to 40 weeks.

Tirzepatide and weight loss

Although the evidence points to tirzepatide being an effective treatment for type 2 diabetes, the manufacturer focused on the results from the SURMOUNT-1 trial in which the drug was administered to overweight or obese patients without type 2 diabetes, with a mean baseline body weight of 105 kg.

The SURMOUNT-1 trial randomised 2,539 participants in a 1:1:1:1 ratio to different doses of tirzepatide (5mg, 10mg or 15mg) or placebo and the treatment was given as an adjunct to a reduced-calorie diet combined with increased physical activity.

All of the participants receiving tirzepatide were started at a dose of tirzepatide 2.5mg once-weekly and then increased in a step-wise approach at four-week intervals to their final randomised maintenance doses. The co-primary endpoints of the study were to show that tirzepatide 10mg and/or 15 mg were superior to placebo in the percentage reduction in body weight compared with baseline and the percentage of participants who achieved a ≥5% body weight reduction at 72 weeks, again compared with placebo.

At the end of the trial, among those taking tirzepatide, average weight reductions were 16.0% (5mg), 21.4% (10mg) and 22.5% (15mg), compared with 2.4% in the placebo arm. Furthermore, the proportion of participants achieving a body weight reduction of ≥5% were 85% (5mg), 89% (10mg), 91% (15mg), and 35% (placebo).

Tirzepatide was also well tolerated with the most commonly reported adverse events being gastrointestinal-related and generally mild to moderate in severity, usually occurring during the dose escalation period. Adverse effects included nausea, diarrhoea, vomiting and constipation which were more frequently experienced compared to placebo. In fact, the overall treatment discontinuation rates due to adverse events were 14.3% (5mg), 16.4% (10mg), 15.1% (15mg) and 26.4% (placebo).

The company is also currently undertaking further trials in overweight patients with type 2 diabetes.