Lilly's Retatrutide and EloraTZP Set New Weight-Loss Benchmarks at EASD

Key points

• Retatrutide, a triple-agonist targeting GLP-1, GIP, and glucagon, resulted in an average weight loss of 49.6 pounds (21% of body weight) over 80 weeks in a Phase 3 trial involving patients with Type 2 diabetes.
• Patients with a BMI of 35 or higher lost an average of 61 pounds on the highest dose of retatrutide, with 31% of participants losing at least 25% of their starting weight.
• EloraTZP, a combination of eloralintide (an amylin receptor agonist) and tirzepatide, achieved an average weight loss of 54.1 pounds (23.3%) in a 48-week Phase 2 trial, outperforming tirzepatide alone, which yielded 34.4 pounds of loss.
• Lilly plans to file for FDA approval of retatrutide as a biologic drug before March 2027, a classification that offers 12 years of market exclusivity compared to five years for small-molecule drugs.
• EloraTZP is set to enter Phase 3 trials by the end of 2026, with Lilly aiming to optimize dosing to improve tolerability, as higher discontinuation rates due to gastrointestinal side effects were observed in Phase 2.

Background

Eli Lilly has been advancing multiple next-generation obesity treatments following the success of Zepbound and Mounjaro. Recent trials have focused on targeting multiple hormonal pathways to achieve greater weight loss and metabolic benefits. Retatrutide and EloraTZP represent distinct approaches: retatrutide is a single-molecule triple agonist, while EloraTZP combines two separate drugs to target GLP-1, GIP, and amylin.

How outlets are covering it

USA Today and The Guardian emphasized the record-breaking weight loss of retatrutide, noting its potential to rival bariatric surgery. CNBC and Eli Lilly focused on EloraTZP, highlighting its superior efficacy over tirzepatide alone but noting higher discontinuation rates due to side effects. Drug pricing experts, cited by USA Today, suggested Lilly’s choice to classify retatrutide as a biologic is a strategic move to extend market exclusivity and prevent generic competition. Analysts, including David Risinger of Leerink Partners, viewed EloraTZP as a potential 'mega-blockbuster' for patients who did not respond to existing GLP-1 therapies.

Why it matters

These results signal a shift in obesity treatment toward multi-hormonal approaches that may offer greater efficacy and broader metabolic benefits. The strategic classification of retatrutide as a biologic could impact long-term pricing and market competition, while the development of EloraTZP provides an alternative for patients who do not achieve desired results with current GLP-1 drugs.

What to watch

Lilly expects to file for FDA approval of retatrutide before March 2027 and will present further data on its effectiveness for obstructive sleep apnea. Phase 3 trials for EloraTZP are set to begin by the end of 2026, with a focus on optimizing dosing to balance efficacy and tolerability. Lilly has also filed lawsuits against compounding pharmacies to block counterfeit versions of retatrutide.