Tirzepatide Yields Top Weight Loss of 20% or More in SURMOUNT Clinical Trial

More than 60% of patients receiving the tirzepatide 15 mg dose lost more than 20% of their baseline weight. ©slam/adobe stock

Use of tirzepatide to treat adults with overweight or obesity resulted in weight loss of up to 22.5% in the SURMOUNT-1 trial, according to findings announced today by Eli Lilly and Company in a press release.

According to the company, the novel, investigational GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) receptor agonist, dosed once weekly, met its coprimary endpoints—superior mean percent change in body weight from baseline and greater percentage of participants achieving weight reductions of at least 5% vs placebo therapy. The 72-week study also achieved its key secondary endpoints.

Tirzepatide has demonstrated efficacy in and is currently under regulatory review for treatment of type 2 diabetes- (T2D) related hyperglycemia. SURMOUNT-1 is the first phase 3 global registration trial to evaluate the new agent’s safety and efficacy in adults without T2D who have obesity or overweight with at least one comorbidity, according to the statement.

SURMOUNT-1 was a multicenter, randomized, double-blind, parallel, placebo-controlled trial comparing the efficacy and safety of tirzepatide at doses of 5 mg, 10 mg, and 15 mg to placebo as an adjunct to diet and physical activity in 2539 adults without T2D with obesity or overweight and 1 of the prespecified comorbidities: hypertension, dyslipidemia, obstructive sleep apnea, or cardiovascular disease.

All patients began treatment at the 2.5 mg weekly dose and were titrated at 4-week intervals to the final randomized doses.

Lilly reports in its release the following for treatment with tirzepatide vs placebo:

Reporting on safety of tirzepatide, the company notes the most commonly reported adverse events were gastrointestinal-related, as is common with the class, and were generally mild to moderate in severity, with most occurring during the dose-escalation period of the trial.

Events experienced more frequently among tirzepatide-treated participants included nausea, diarrhea, vomiting, and constipation. The overall treatment discontinuation rates were 14.3% (5 mg), 16.4% (10 mg), 15.1% (15 mg) and 26.4% (placebo).

SURMOUNT-1 participants identified at the start of the study as having prediabetes will remain enrolled for another 104 weeks, the company explains, to assess the impact of tirzepatide vs placebo on bodyweight and differences in progression to diabetes after 3 years of treatment.

"Obesity is a chronic disease that often does not receive the same standard of care as other conditions, despite its impact on physical, psychological and metabolic health, which can include increased risk of hypertension, heart disease, cancer and decreased survival," said Louis J. Aronne, MD, director of the Comprehensive Weight Control Center, the Sanford I. Weill Professor of Metabolic Research at Weill Cornell Medicine, and SURMOUNT-1 investigator, in the Lilly statement. Aronne who is also an expert in obesity at New York Presbyterian/Weill Cornell Medical Center continued, “Tirzepatide delivered impressive body weight reductions in SURMOUNT-1 which could represent an important step forward for helping the patient and physician partnership treat this complex disease."

According to the press statement, Lilly expects to present the SURMOUNT-1 findings at a future medical meeting and to submit them to a peer-reviewed journal.

The SURMOUNT phase 3 global clinical development program for tirzepatide began in late 2019 and has enrolled more than 5000 people with obesity or overweight across 6 clinical trials of which 4 are global studies. Results from SURMOUNT-2, -3, and -4 are anticipated in 2023.