Cagrilintide vs Retatrutide
Cagrilintide (AM833), from Novo Nordisk, is a long-acting amylin analogue. Retatrutide (LY3437943), from Lilly, is a triple agonist of the GLP-1, GIP and glucagon receptors. They work on different hormone systems, which is why researchers ask about them together. This page compares them as research compounds.
| Cagrilintide | Retatrutide | |
|---|---|---|
| Developer | Novo Nordisk | Eli Lilly |
| Development code | AM833 | LY3437943 |
| Receptor targets | Amylin and calcitonin receptors | GLP-1, GIP and glucagon receptors |
| Mechanism family | Amylin analogue | Incretin and glucagon agonist |
| Administration in trials | Once weekly subcutaneous | Once weekly subcutaneous |
| Phase 3 result | REDEFINE 1: 11.5% alone, 20.4% with semaglutide, at 68 weeks (placebo 3.0%) | TRIUMPH-1: up to 25.0% at 80 weeks (placebo 3.9%) |
| Status | Phase 3 alone (RENEW); with semaglutide, under US review | Phase 3; Lilly plans a US filing in early 2027 |
| Peptx availability | Factory Direct kits (5mg, 10mg, 20mg) | UK single vials and Factory Direct kits |
- Developer
- Novo NordiskEli Lilly
- Development code
- AM833LY3437943
- Receptor targets
- Amylin and calcitonin receptorsGLP-1, GIP and glucagon receptors
- Mechanism family
- Amylin analogueIncretin and glucagon agonist
- Administration in trials
- Once weekly subcutaneousOnce weekly subcutaneous
- Phase 3 result
- REDEFINE 1: 11.5% alone, 20.4% with semaglutide, at 68 weeks (placebo 3.0%)TRIUMPH-1: up to 25.0% at 80 weeks (placebo 3.9%)
- Status
- Phase 3 alone (RENEW); with semaglutide, under US reviewPhase 3; Lilly plans a US filing in early 2027
- Peptx availability
- Factory Direct kits (5mg, 10mg, 20mg)UK single vials and Factory Direct kits
Two different hormone systems
Cagrilintide mimics amylin, the hormone released with insulin that acts in the brainstem on fullness and meal size, and it activates both amylin and calcitonin receptors. Retatrutide works through the incretin and glucagon receptors instead: GLP-1 and GIP, as in tirzepatide, plus glucagon.
Because the pathways barely overlap, the useful research question is less which one is stronger and more what happens when an amylin compound is added to an incretin one.
What the trials show
Cagrilintide's largest trial is REDEFINE 1, published in the New England Journal of Medicine in 2025. Over 68 weeks, cagrilintide alone lowered body weight by 11.5%, semaglutide alone by 14.9% and the two together by 20.4%, against 3.0% on placebo. An earlier 26-week Phase 2 found dose-dependent reductions of 6.0% to 10.8%, and Novo Nordisk started a Phase 3 programme for cagrilintide on its own, RENEW, in November 2025.
Retatrutide's TRIUMPH-1 trial, published in the New England Journal of Medicine in September 2026, reported reductions of 17.6% to 25.0% at 80 weeks across its 4mg, 9mg and 12mg doses, against 3.9% on placebo. The trials differ in design and length, so the numbers are not a head-to-head comparison.
Have they been studied together?
Not in people. No registered human trial combines cagrilintide with retatrutide. The first study of the pairing was in animals: researchers at the University of Copenhagen reported in Nature Metabolism in September 2026 that the combination produced more weight loss in obese male rats than either compound alone at the same doses.
The closest human data pairs an amylin compound with an incretin one: cagrilintide with semaglutide in REDEFINE, and Lilly's eloralintide with tirzepatide, which reached 23.3% in a 48-week Phase 2b reported in September 2026.
Bottom line for research labs
Cagrilintide and Retatrutide answer different research questions. Retatrutide is the reference for single-molecule multi-agonism, with the larger Phase 3 dataset. Cagrilintide is the best-documented amylin analogue. What the two do together has so far only been tested in animals.