Eli Lilly’s Retatrutide Sets New Weight-Loss Benchmarks in Phase 3 Trials

Key points

• In the TRIUMPH-1 trial for adults without diabetes, the 12mg dose of retatrutide resulted in an average 25% weight loss after 80 weeks, with some participants reaching 30% loss after two years.
• The TRIUMPH-2 trial for adults with type 2 diabetes showed an average 18.8% weight loss at the highest dose, with 72% of participants achieving normal blood sugar levels.
• Retatrutide is a triple agonist targeting GLP-1, GIP, and glucagon, aiming to combine appetite suppression with increased energy expenditure.
• Side effects were primarily gastrointestinal, with nausea reported in 42% of the highest-dose group in the non-diabetic trial and diarrhea in 27-34% of the diabetic trial participants.
• Eli Lilly plans to submit the data to the FDA for approval early next year.

Background

Retatrutide follows the success of GLP-1 and dual-agonist drugs like semaglutide and tirzepatide. Previous coverage noted that while these drugs offer significant benefits, they carry risks such as muscle loss and potential hair shedding. The current trials represent a shift toward multi-agonist therapies to overcome plateaus in weight loss and address comorbidities like diabetes and cardiovascular risk factors.

How outlets are covering it

ScienceAlert and The Guardian emphasized the drug’s efficacy in reducing weight and improving comorbidities like knee pain and sleep apnea, highlighting the 25% weight loss in non-diabetics. Scientific American focused on the 'high-water mark' of weight loss in diabetic patients, noting that 60% of the highest-dose group no longer met obesity criteria. CNBC contextualized retatrutide within a broader industry trend, noting that while retatrutide is a triple agonist, the next frontier may involve amylin-targeting drugs like eloralintide, which can be combined with existing GLP-1s to further enhance weight loss for those who do not respond fully to current therapies.

Why it matters

Retatrutide’s results suggest a potential new standard for obesity treatment, offering substantial weight loss and metabolic improvements comparable to bariatric surgery. Its approval could expand treatment options for millions of patients, particularly those with type 2 diabetes or those who have not achieved sufficient results with current GLP-1 therapies. However, the side effect profile and long-term safety data will be critical for regulatory approval and widespread adoption.

What to watch

Eli Lilly intends to submit the trial data to the FDA and other global health agencies for approval early next year. Phase 3 trials for combination therapies involving amylin and GLP-1 are also underway, which may offer additional options for patients who do not respond fully to single or dual agonists.