Japanese adults with obesity lose weight with once-weekly tirzepatide

Taking tirzepatide once a week appears to result in clinically meaningful reductions in body weight for Japanese adults with obesity, according to the results of the phase III multicentre SURMOUNT-J trial

SURMOUNT-J included 267 Japanese adults with BMI of at least 27 kg/m² plus at least two obesity-related health disorders or BMI of at least 35 kg/m² accompanied by at least one obesity-related health disorder, excluding diabetes.

The participants were randomly assigned to receive subcutaneous tirzepatide 10 or 15 mg or placebo once a week for 72 weeks. The mean percent change in bodyweight and the proportion of participants achieving at least 5-percent decrease in body weight at week 72 were assessed as coprimary endpoints.

A total of 225 participants (mean age 50.8 years, 59 percent male) were included in the modified intention-to-treat analysis due to exclusion of one study site. Of these, 73 were in the tirzepatide 10-mg group, 77 in the tirzepatide 15-mg group, and 75 in the placebo group. Some 192 participants (85 percent) completed the study.

Compared with placebo, tirzepatide resulted in significantly greater reductions in body weight (estimated treatment differences, −16.1 percent with 10 mg and −21.1 percent with 15 mg; p<0.0001 for both). Furthermore, a higher percentage of participants achieved at least 5-percent body weight reduction with tirzepatide 10 mg (94 percent) and 15 mg (96 percent) than with placebo (20 percent; p<0.0001 for both).

Tirzepatide was also associated with improvements in cardiometabolic and body composition indices.

In terms of safety, treatment-emergent adverse events more frequently occurred with tirzepatide than with placebo (10 mg: 84 percent; 15 mg: 86 percent; and 69 percent). The most common events were gastrointestinal symptoms. Adverse events led to study discontinuations in one participant on 10-mg tirzepatide and three of those on placebo.