Cagrilintide: A Long-Acting Amylin Analog with Strong Combination Data and Thin Standalone Evidence

Cagrilintide is one of the more genuinely promising compounds you’ll see floating around on gray-market peptide menus. It’s also one where the gap between the exciting science and what a person can actually buy is at its widest. It’s an investigational (still being tested, not yet approved) once-weekly lab-made copy of amylin, a hormone your pancreas releases alongside insulin to tell your brain you’re full. Novo Nordisk has put it through large, carefully run randomized trials (studies where people are sorted into treatment groups by chance) published in top journals. But here’s the catch: almost all of that strong evidence is for cagrilintide combined with semaglutide in a single fixed-dose product called CagriSema, not for cagrilintide by itself. The standalone drug, which is the version being sold informally, has only early human support and no approved product anywhere in the world.

What it is

Cagrilintide is a 37-amino-acid lipidated peptide (a small protein with a fat chain attached) built on the structure of human amylin (also called islet amyloid polypeptide). Natural amylin doesn’t last long in the body and tends to clump into sticky fibers, so chemists redesigned the molecule to fix both problems. According to the development paper by Kruse and colleagues, swapping the building blocks at positions 14 and 17 creates a “salt bridge” (an internal chemical bond) that keeps the peptide’s core spiral shape stable, while three changes to proline (positions 25, 28 and 29) make it less likely to clump. A fatty-acid chain attached through a linker lets the peptide grab onto albumin (a protein in your blood) and let go again, the same trick used to make semaglutide and insulin degludec last longer. The payoff is a half-life (the time it takes for half the drug to clear) of roughly 159 to 195 hours, long enough for a once-weekly shot under the skin.

As for how it works: cagrilintide switches on the amylin receptors and the calcitonin receptor, a family of related “signal-catching” proteins. It acts on the parts of the brain that control appetite, in the brainstem and hypothalamus, to cut hunger, help you feel full, and slow down how fast your stomach empties. Because that route is different from how GLP-1 drugs like semaglutide work, the two are thought to team up well, which is the whole reason for pairing them in CagriSema.

The claims

In proper clinical development, cagrilintide is being studied for long-term weight management in people who are overweight or have obesity, and as part of CagriSema for combined weight loss and blood-sugar control in type 2 diabetes.

On gray-market “research-use-only” peptide sites, it’s sold as a weight-loss and appetite-suppression peptide, often bundled with semaglutide or tirzepatide and packaged with suggested doses and “stacking” tips. None of those products are FDA-approved, dispensed by a pharmacy, or quality-checked, and none of the vendor advice has been through regulatory review. A marketing page is not evidence, and this profile doesn’t cover dosing.

The evidence

The human data set is unusually large for a compound in this category, but you have to read it carefully.

The first human combination data came from a phase 1b trial (Enebo and colleagues, The Lancet 2021), a placebo-controlled study that slowly raised the dose in 96 randomly assigned participants at a single US center. It showed that cagrilintide and semaglutide could be ramped up together with no meaningful interaction between the two drugs, confirmed the long half-life, and produced more weight loss with the combination than with placebo (a dummy treatment). The key thing to notice: every active group in that study also got semaglutide, so the weight-loss numbers are combination results, not cagrilintide on its own.

The main standalone human data set is a phase 2 dose-finding trial (Lau and colleagues, The Lancet 2021): 706 adults with obesity but without diabetes, randomly assigned across 57 sites in 10 countries, with a placebo group and an active comparison drug (liraglutide), over 26 weeks. Cagrilintide on its own produced 6.0% to 10.8% weight loss across the doses tested, versus 3.0% for placebo, and the top 4.5 mg dose (10.8%) modestly beat liraglutide 3.0 mg (9.0%). That’s a real result, but it’s a single dose-finding study, not a make-or-break trial.

A phase 2 CagriSema trial in type 2 diabetes (Frias and colleagues, The Lancet 2023) ran 32 weeks across 17 US sites and showed the combination beat either drug alone on both weight and blood sugar.

The pivotal (decisive) evidence is REDEFINE 1 (NEJM 2025; ClinicalTrials.gov NCT04657458), a phase 3 trial of 3,417 adults with obesity and no diabetes, randomly assigned to CagriSema, cagrilintide alone, semaglutide alone, or placebo over 68 weeks. Weight reductions (using the trial-product estimand, a way of measuring the effect of staying on the treatment) were 22.7% for CagriSema, 16.1% for semaglutide, 11.8% for cagrilintide alone, and 2.3% for placebo; more than 60% of CagriSema patients lost at least 20% of their body weight. Two cautions matter here. First, Novo had pointed toward roughly 25%, so the 22.7% result was widely seen as a letdown, and the stock dropped about 20% when the December 2024 topline came out. Second, only around 57% of CagriSema patients reached the maximum target dose, which makes the headline numbers harder to read cleanly. REDEFINE 2 (NEJM 2025), in 1,206 adults with type 2 diabetes, showed 15.7% weight loss with CagriSema versus about 3.1% for placebo over 68 weeks.

The cagrilintide-alone result (11.8% versus 2.3%) was presented as a REDEFINE 1 sub-analysis at the EASD meeting in September 2025 and billed as the first phase 3 data for a long-acting amylin used by itself. On the strength of that, Novo announced a dedicated standalone program, RENEW, starting in late 2025. No standalone (cagrilintide-only) efficacy trial has reported results yet.

Animal work backs up the mechanism: a 2025 eBioMedicine study (Carvas and colleagues) showed in mice that cagrilintide’s weight-lowering effect depends on specific amylin receptors, with a much weaker response in animals bred to lack them. A 2025 cryo-EM study (a technique that images frozen molecules at high detail) in Nature Communications (Cao and colleagues) mapped exactly how the drug latches onto the calcitonin and amylin receptors.

What’s missing is significant: no finished standalone trial proving it works alone, no long-term outcome data (heart events, deaths, or whether the effect lasts beyond about 68 weeks), and basically no large independent confirmation, since the pivotal and most mechanism studies are funded by or written by Novo Nordisk.

Safety and side effects

The best-documented side effects are gut-related. In REDEFINE 1, gastrointestinal (stomach and gut) events happened in 79.6% of CagriSema patients versus 39.9% on placebo, including nausea (55%), constipation (30.7%) and vomiting (26.1%), mostly mild-to-moderate and short-lived. About 6% of people on CagriSema stopped because of side effects, versus 3.7% on placebo. In the phase 2 monotherapy (single-drug) trial, gut side effects ran 41% to 63% across the cagrilintide doses versus 32% for placebo.

Several warnings that circulate online are borrowed from the broader drug class rather than being cagrilintide findings. Gallbladder problems are a known risk of rapid weight loss in general, but no cagrilintide-specific rate has been published. Pancreatitis (inflammation of the pancreas) is a theoretical class concern, not a confirmed signal. Thyroid C-cell tumor worries come from the labeling on GLP-1 drugs, based on rodent studies; because cagrilintide also acts on the calcitonin receptor, the question is fair to raise, but there’s no approved cagrilintide label and no human data showing it actually happens. Most importantly, the long-term human safety is genuinely unknown, since the longest trials run only about 68 weeks.

The honest summary: over the short to medium term, the tolerability picture is mostly about manageable gut effects, serious events in trials were rare, and longer-term safety simply hasn’t been pinned down.

Legal and regulatory status

Cagrilintide is not approved anywhere as of June 2026. Novo Nordisk submitted a New Drug Application for CagriSema (the combination, for weight management) to the FDA on December 18, 2025, with review expected during 2026. Cagrilintide as a standalone drug hasn’t been filed; its dedicated phase 3 program has only just begun. The one amylin-class drug already approved is pramlintide (Symlin), approved by the FDA in March 2005 and taken as several injections a day at main meals; cagrilintide is being positioned as the once-weekly, next-generation successor.

For athletes: cagrilintide isn’t listed by name on the WADA Prohibited List, but as an investigational drug that no government health authority has approved for human use, it falls under Section S0 (non-approved substances), which is banned at all times, both in and out of competition. Treat it as banned in sport and double-check through Global DRO.

The gray-market products sold as cagrilintide are unapproved, unregulated, and of unverified identity and purity. There’s no legal way to use these products in humans in the US.

Bottom line

Cagrilintide sits in a genuinely unusual spot. The combination it anchors, CagriSema, has some of the strongest randomized human data of any compound talked about on peptide forums, with multiple large phase 3 trials and NEJM publication. But that evidence is for the combination, not the standalone drug, and even the pivotal trial came in under the company’s own expectations and exposed a problem with getting people up to the full dose. The cagrilintide-alone story rests on one dose-finding phase 2 trial and a single phase 3 sub-analysis, with the dedicated standalone program still under way and no long-term safety data in hand. It’s a serious drug with a serious development program, which is exactly why it deserves a finished, approved product and a real label rather than an unregulated vial. For now the grade is preliminary human: promising, well-studied as a combination, but unfinished as the thing being sold.

Evidence grade: 7/10 · Moderate.

Sources

• Enebo et al., phase 1b combination, Lancet 2021 (PubMed)
• Lau et al., phase 2 monotherapy, Lancet 2021 (PubMed)
• Frias et al., phase 2 CagriSema in T2D, Lancet 2023
• Kruse et al., Development of Cagrilintide, J Med Chem 2021
• REDEFINE 1, NEJM 2025 (NCT04657458)
• REDEFINE 2, NEJM 2025
• REDEFINE 1 topline press release (Novo Nordisk)
• Market reaction to December 2024 topline (CNBC)
• Carvas et al., animal mechanism, eBioMedicine 2025 (PMC)
• Cao et al., cryo-EM structure, Nature Communications 2025
• CagriSema FDA filing, December 2025 (Novo Nordisk)
• Standalone RENEW program announcement, EASD 2025 (GlobeNewswire)
• Cagrilintide as a next obesity drug candidate (CNBC)
• WADA Prohibited List
• WADA Section S0 (non-approved substances)