Cagrilintide: Amylin Reimagined for GLP-1
Amylin Analogs
20.4% weight loss
In the REDEFINE 1 Phase 3 trial, cagrilintide combined with semaglutide (CagriSema) produced 20.4% body weight reduction at 68 weeks in 3,417 adults with obesity, compared to 3.0% with placebo.
Garvey et al., NEJM, 2025
Garvey et al., NEJM, 2025
View as imageAmylin is a 37-amino-acid peptide co-secreted with insulin from pancreatic beta cells. It reduces food intake, slows gastric emptying, and suppresses glucagon secretion. Pramlintide, the only approved amylin analog, failed commercially because it required three injections per day and produced modest weight loss. Cagrilintide is Novo Nordisk's attempt to fix everything wrong with pramlintide: a long-acting, once-weekly, lipidated amylin analog designed from the start to combine with semaglutide. That combination, branded CagriSema, produced the largest weight loss numbers seen in any Phase 3 obesity trial to date. This article covers cagrilintide's design, receptor pharmacology, clinical trial results, and what the data means for the future of amylin-based obesity treatment.
Key Takeaways
- Cagrilintide is a lipidated, acylated analog of human amylin with structural modifications that extend its half-life to enable once-weekly subcutaneous dosing, solving pramlintide's three-times-daily injection problem.[1]
- In the REDEFINE 1 Phase 3 trial (3,417 adults with obesity, no diabetes), CagriSema produced 20.4% weight loss at 68 weeks versus 3.0% with placebo, 12.1% with semaglutide alone, and 8.0% with cagrilintide alone.[6]
- In the REDEFINE 2 trial (adults with T2D and obesity), CagriSema reduced HbA1c by 2.2 percentage points and body weight by 15.7% at 68 weeks, outperforming semaglutide monotherapy on both endpoints.[7]
- Cagrilintide (AM833) activates both amylin receptors (AMY1, AMY2, AMY3) and calcitonin receptors (CTR), giving it a broader receptor profile than native amylin or pramlintide.[4]
- Gastrointestinal adverse events (nausea, vomiting, diarrhea) affected 79.6% of CagriSema recipients versus 39.9% on placebo, though most were mild-to-moderate and transient.[6]
- CagriSema has not yet been approved by any regulatory agency. Novo Nordisk submitted for FDA approval in late 2025 based on the REDEFINE program.
How cagrilintide was built
Kruse et al. (2021) published the medicinal chemistry behind cagrilintide in the Journal of Medicinal Chemistry. The design started with human amylin's amino acid sequence and introduced three categories of modification:[1]
Amino acid substitutions to prevent the aggregation and fibrillation that makes native amylin unstable. Human amylin forms toxic amyloid fibrils (a pathological feature of type 2 diabetes), so the substitutions were engineered to maintain receptor binding while eliminating the tendency to self-aggregate.
Lipidation with a fatty acid chain attached via a linker, enabling the peptide to bind reversibly to serum albumin. This albumin binding dramatically extends the plasma half-life. Native amylin has a half-life of approximately 15 minutes. Pramlintide's half-life is approximately 50 minutes. Cagrilintide's albumin-binding design extends the effective duration to support once-weekly dosing.[1]
Backbone modifications to resist enzymatic degradation while maintaining the correct three-dimensional conformation for receptor activation.
The result is a peptide that acts like amylin at its target receptors but behaves like an albumin-bound long-acting drug in the bloodstream. This is the same lipidation strategy Novo Nordisk used for semaglutide (a long-acting GLP-1 analog) and insulin degludec (a long-acting insulin), applied to a new target biology.
Receptor pharmacology: more than just amylin
Fletcher et al. (2021) characterized AM833 (cagrilintide's research designation) across the full family of calcitonin-related receptors. The results revealed that cagrilintide is not a selective amylin receptor agonist. It activates multiple receptor subtypes:[4]
Amylin receptors (AMY1, AMY2, AMY3) are formed when the calcitonin receptor (CTR) or calcitonin receptor-like receptor (CLR) pairs with receptor activity-modifying proteins (RAMPs). These are the primary targets for appetite suppression and gastric emptying effects.
Calcitonin receptor (CTR) is activated directly by cagrilintide without the need for RAMP co-expression. This gives cagrilintide effects on bone metabolism and calcium handling that native amylin and pramlintide do not share to the same degree.
The dual amylin-calcitonin receptor agonism distinguishes cagrilintide from pramlintide (which is more selective for amylin receptors) and may contribute to its greater efficacy for weight loss. Research by Carvas et al. (2025) demonstrated that cagrilintide lowers body weight specifically through brain amylin receptors 1 and 3, identifying the neural circuits responsible for its anorectic effects.[4]
Phase 1b: establishing the combination
Enebo et al. (2021) published the Phase 1b trial in The Lancet, testing escalating doses of cagrilintide (0.16 to 4.5 mg weekly) co-administered with semaglutide 2.4 mg in adults with overweight or obesity. This study established three critical findings:[3]
First, cagrilintide and semaglutide do not interact pharmacokinetically. The exposure to each drug was unaffected by co-administration, meaning neither drug altered the absorption, distribution, or elimination of the other. This is essential for a fixed-dose combination.
Second, the combination was well tolerated. Most adverse events were gastrointestinal (nausea, vomiting, decreased appetite) and were mild to moderate. The safety profile was consistent with what would be expected from each component individually.
Third, body weight reductions with the combination exceeded what either drug achieved alone, suggesting additive or synergistic effects on appetite regulation through distinct neural pathways (GLP-1 receptor activation plus amylin/calcitonin receptor activation).[3]
Phase 2: the weight loss signal
Lau et al. (2021) published the Phase 2 dose-finding trial in The Lancet. Adults with overweight or obesity (BMI 27-40 kg/m2) were randomized to one of seven cagrilintide doses (0.3 to 4.5 mg weekly), liraglutide 3.0 mg daily (as an active comparator), or placebo, all for 26 weeks.[2]
At the highest dose (4.5 mg), cagrilintide produced 10.8% weight loss at 26 weeks versus 3.0% with placebo and 9.0% with liraglutide 3.0 mg. The dose-response was clear and linear: higher cagrilintide doses produced greater weight loss. Cagrilintide at 4.5 mg outperformed liraglutide (a first-generation GLP-1 analog) as monotherapy, establishing that amylin receptor agonism alone produces clinically meaningful weight loss.[2]
Frias et al. (2023) tested CagriSema (cagrilintide 2.4 mg + semaglutide 2.4 mg) in adults with type 2 diabetes and obesity in a Phase 2 trial. At 32 weeks, CagriSema produced 15.6% weight loss versus 5.1% for semaglutide alone and 8.1% for cagrilintide alone. The HbA1c reduction was 2.2 percentage points for CagriSema versus 1.8 for semaglutide and 0.9 for cagrilintide. The combination was superior to both monotherapies for weight loss and matched semaglutide for glycemic control.[5]
REDEFINE: the Phase 3 program
The REDEFINE clinical program produced two landmark New England Journal of Medicine publications in 2025, providing the data that will determine whether CagriSema receives regulatory approval.
REDEFINE 1: obesity without diabetes
Garvey et al. (2025) randomized 3,417 adults with BMI 30 or higher (or 27 or higher with comorbidities) to CagriSema, semaglutide alone, cagrilintide alone, or placebo for 68 weeks. Key results:[6]
- CagriSema: 20.4% body weight reduction
- Semaglutide 2.4 mg alone: 12.1% reduction
- Cagrilintide 2.4 mg alone: 8.0% reduction
- Placebo: 3.0% reduction
The 20.4% figure is the largest mean weight loss reported in a Phase 3 obesity drug trial. It exceeds semaglutide 2.4 mg (Wegovy) by approximately 8 percentage points and approaches the results seen with bariatric surgery in some populations. The combination's superiority over both monotherapies demonstrates genuine pharmacological synergy: the whole exceeds the sum of its parts.
More than half of CagriSema recipients achieved at least 20% weight loss, and approximately one-third achieved 25% or more. These responder rates are clinically transformative because they enter the weight-loss range associated with resolution of type 2 diabetes, sleep apnea, and other obesity-related comorbidities.
Gastrointestinal adverse events were the primary safety signal, affecting 79.6% of CagriSema recipients versus 39.9% on placebo. Nausea (45.5%), diarrhea (25.0%), vomiting (20.4%), and constipation (18.3%) were the most common. Most events were transient and mild-to-moderate, occurring during the dose-escalation phase and resolving as patients reached maintenance dosing.[6]
REDEFINE 2: type 2 diabetes with obesity
Davies et al. (2025) tested CagriSema in adults with type 2 diabetes and overweight or obesity, the population most likely to use the drug in clinical practice. At 68 weeks, CagriSema produced:[7]
- HbA1c reduction: 2.2 percentage points (vs. 1.6 for semaglutide alone)
- Weight loss: 15.7% (vs. 8.3% for semaglutide alone)
- Proportion achieving HbA1c below 7%: higher with CagriSema than semaglutide alone
The dual-pathway approach proved particularly effective in the T2D population, where both glycemic control and weight management are therapeutic goals. Amylin's effects on glucagon suppression and gastric emptying complement GLP-1's insulin secretion enhancement, producing metabolic benefits through mechanistically distinct pathways.
Why combining amylin and GLP-1 works
The pharmacological rationale for CagriSema rests on the observation that amylin and GLP-1 suppress appetite through different brain circuits. GLP-1 receptors in the hypothalamus and brainstem mediate satiety through one set of neural pathways. Amylin receptors in the area postrema and nucleus of the solitary tract mediate satiety through a partly overlapping but distinct set of pathways.
D'Ascanio et al. (2024) reviewed the evidence for this complementary mechanism, noting that combination therapy targets both the GLP-1-responsive and amylin-responsive circuits simultaneously, reducing the compensatory responses that limit weight loss with either pathway alone. When the body adapts to GLP-1 agonism (reducing the weight-loss response over time), the amylin pathway continues to suppress appetite through independent circuits, and vice versa.[8]
This explains why CagriSema's 20.4% weight loss exceeds the simple addition of cagrilintide's 8.0% and the incremental benefit over semaglutide's 12.1%. The combination overcomes homeostatic weight-defense mechanisms more effectively than either agent alone because it disrupts appetite signaling at multiple neural nodes simultaneously.
Limitations and open questions
Not yet approved. CagriSema has not received FDA or EMA approval as of March 2026. Novo Nordisk submitted regulatory applications in late 2025 based on the REDEFINE data. The review process, potential label restrictions, and pricing decisions will determine real-world access.
GI tolerability burden. Nearly 80% of CagriSema recipients experienced gastrointestinal adverse events. While most were transient, this tolerability profile will affect real-world adherence. Some patients who tolerate semaglutide alone may find the combination's added GI burden unacceptable.
Weight regain after discontinuation. The REDEFINE trials measured on-treatment effects at 68 weeks. The durability of weight loss after CagriSema discontinuation has not been published. Experience with semaglutide monotherapy suggests that most weight is regained after stopping treatment, and there is no reason to expect CagriSema will differ.
Long-term safety. The REDEFINE trials provide 68-week safety data. Long-term effects of chronic dual amylin-calcitonin/GLP-1 receptor activation are unknown. Cagrilintide's calcitonin receptor activity raises theoretical questions about bone metabolism with long-term use, though no bone-related adverse signals emerged in the trials.
Cost and access. CagriSema will likely be priced at a premium to semaglutide monotherapy. Given that GLP-1 agonist costs are already a barrier for many patients, adding a second peptide component may further restrict access.
Competition. Tirzepatide (a dual GIP/GLP-1 agonist) has already demonstrated approximately 22.5% weight loss in some trials. Survodutide (a glucagon/GLP-1 dual agonist) and retatrutide (a GIP/GLP-1/glucagon triple agonist) are also in development. CagriSema's competitive positioning depends on whether its unique amylin mechanism offers advantages beyond weight loss percentages alone.
The Bottom Line
Cagrilintide represents the successful re-engineering of amylin pharmacology for the modern obesity treatment landscape. By solving pramlintide's short half-life through lipidation and combining with semaglutide, Novo Nordisk created a dual-pathway therapy (CagriSema) that produced 20.4% weight loss in the REDEFINE 1 Phase 3 trial. The combination outperformed both monotherapies through complementary appetite-suppression mechanisms in the brain. Whether this translates to regulatory approval, acceptable GI tolerability in real-world use, and sustainable weight management remains to be determined.