Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2): a double-blind, parallel-group, randomised,...

Retatrutide is an agonist of GIP, GLP-1, and glucagon receptors, and is currently under investigation for the treatment of obesity, type 2 diabetes, and other comorbidities, including knee osteoarthritis and obstructive sleep apnoea. We aimed to assess the efficacy and safety of retatrutide in adults with obesity and type 2 diabetes.

TRIUMPH-2 was a double-blind, parallel-group, randomised, placebo-controlled, phase 3 trial conducted at 92 medical and research centres and hospitals across eight countries. We enrolled adults (aged ≥18 years) with a BMI of 27 kg/m² or higher and type 2 diabetes (glycated haemoglobin [HbA_1c] 6·5-10·5%) on stable treatment for type 2 diabetes for at least 90 days before screening (diet or exercise alone, or up to three oral glucose-lowering medications), and a history of at least one self-reported unsuccessful dietary effort to reduce bodyweight. Participants were randomly assigned (1:1:1:1), using an interactive web-response system, to receive once-weekly subcutaneous injections (self-administered) of placebo or retatrutide 4 mg, 9 mg, or 12 mg. The primary endpoint was the percentage change from baseline to week 80 in bodyweight for the retatrutide 9 mg and 12 mg doses versus placebo, with 4 mg versus placebo a key secondary endpoint. Efficacy analyses included all randomly assigned participants, with missing data imputed with a primary multiple imputation strategy for the treatment regimen estimand. Safety analyses included all randomly assigned participants who received at least one dose of study drug. This trial is registered with ClinicalTrials.gov, NCT05929079 (completed).

Between July 11, 2023, and Nov 1, 2024, 2047 participants were screened, and 1152 (mean age 55·1 years [SD 10·8], 554 [48%] females and 598 [52%] males, and 672 [58%] of White ethnicity) were randomly assigned to retatrutide 4 mg (n=292), 9 mg (n=284), or 12 mg (n=287), or placebo (n=289). At baseline, the mean BMI was 38·2 kg/m² (SD 7·4), mean HbA_1c was 7·71% (1·07), median duration of obesity was 21 years (IQR 11-31), and median duration of diabetes was 5·6 years (2·6-10·4). At baseline, 1055 (92%) of 1152 participants were on any oral glucose-lowering medication, including biguanides, SGLT2 inhibitors, sulfonylureas, and other oral glucose-lowering medications. Of 1152 participants, 965 (84%) completed the study drug. For the treatment regimen estimand, the mean percentage change from baseline in bodyweight at week 80 was -11·9% (SE 0·6) with retatrutide 4 mg, -16·8% (0·7) with retatrutide 9 mg, -18·8% (0·7) with retatrutide 12 mg, and -5·1% (0·7) with placebo. Estimated treatment differences compared with placebo for percentage change in bodyweight were -6·9% (95% CI -8·7 to -5·1) with retatrutide 4 mg, -11·8% (-13·7 to -9·8) with retatrutide 9 mg, and -13·8% (-15·8 to -11·8) with retatrutide 12 mg (p<0·0001 for all). The most frequently reported adverse events were gastrointestinal, which were more common in the retatrutide groups than in the placebo group (diarrhoea occurred in 80 [27%] of 292 participants in the 4 mg group, 95 [34%] of 284 in the 9 mg group, and 96 [34%] of 286 in the 12 mg group vs 38 [13%] of 287 in the placebo group, and nausea occurred in 40 [14%], 59 [21%], and 80 [28%] vs 23 [8%]). Hypotension and dysesthesia were more frequent with retatrutide than with placebo (four [1%] in the 4 mg group, 14 [5%] in the 9 mg group, and 18 (6%) in the 12 mg group vs one [<1%] in the placebo group with hypotension; 13 [4%], 16 [6%], and 21 [7%] vs two [1%] in the placebo group with dysesthesia). Permanent treatment discontinuation due to adverse events or death was more frequent in participants treated with retatrutide 9 mg (33 [12%]) and 12 mg (22 [8%]) compared with retatrutide 4 mg (11 [4%]) and placebo (14 [5%]). Two participants died in the retatrutide 4 mg group, three in the 9 mg group, one in the 12 mg group, and one in the placebo group; all deaths were deemed to be unrelated to the study intervention by the investigator.

Treatment with retatrutide resulted in substantial improvements in bodyweight and was associated with improvements in glycaemic control in participants with obesity and type 2 diabetes, with a safety profile generally consistent with other molecules with GLP-1 receptor agonism. These results show that retatrutide might be effective for the treatment of obesity in people with type 2 diabetes.

Eli Lilly and Company.