CagriSema's FDA Decision: What It Is, What the Trials Showed, and What to Watch

What CagriSema is

CagriSema is a fixed combination of two peptides given as one weekly injection under the skin. Semaglutide is the GLP-1 receptor agonist sold as Wegovy for weight management and Ozempic for type 2 diabetes. Cagrilintide is an amylin analogue. Amylin is a hormone the pancreas releases alongside insulin, and it slows stomach emptying and signals fullness through a different receptor system than GLP-1.

The logic of combining them is that they act on separate appetite pathways, so their effects should add rather than overlap. Novo Nordisk submitted the application to FDA on December 18, 2025 ¹. The compound is approved nowhere as of September 30, 2026, and the review concerns weight management in adults.

Why add an amylin analogue to a GLP-1 drug

Amylin is released by the same beta cells that release insulin, in roughly the same proportion, and it does three things after a meal: it slows the stomach emptying, it suppresses glucagon, and it signals fullness in the hindbrain. Those receptors are not GLP-1 receptors, which is the whole premise of combining the two. A drug acting on one appetite pathway eventually meets a ceiling; two pathways should push further before the body adapts.

Cagrilintide is a long-acting version of that hormone, engineered so a single weekly injection holds the signal. It has been tested on its own: in a phase 2 trial in people with overweight or obesity, weekly cagrilintide produced up to about 10.8% weight loss over 26 weeks ². That is a real effect, well short of what semaglutide does alone, and it is the component REDEFINE 1 kept as a separate comparator arm so the combination could be measured against each half.

The practical consequence is that CagriSema is not a reformulated semaglutide. It is two active drugs, with two mechanisms and two side-effect profiles arriving together, which is also why the gastrointestinal event rate is higher than semaglutide's alone.

REDEFINE 1: the trial the application rests on

REDEFINE 1 was a 68-week phase 3a trial in 3,417 adults without diabetes who had a BMI of 30 or higher, or 27 or higher with at least one obesity-related complication. Participants were randomised to CagriSema, semaglutide 2.4 mg alone, cagrilintide 2.4 mg alone, or placebo, each with lifestyle intervention ³.

Mean body weight fell 20.4% on CagriSema against 3.0% on placebo, a difference of 17.3 percentage points. More participants reached every weight-loss threshold the trial measured, including reductions of 20%, 25% and 30% or more. Gastrointestinal adverse events affected 79.6% of the CagriSema group against 39.9% on placebo, and were mostly transient and mild to moderate ³.

A separate analysis of the same trial looked at blood pressure. Systolic pressure fell 10.9 mm Hg on CagriSema against 2.8 on placebo, 63.0% of the CagriSema group reached blood-pressure targets against 32.0%, and among participants taking blood-pressure medicines, 39.6% reduced or stopped them against 18.8% on placebo ⁴.

Why two different numbers circulate

When REDEFINE 1 first reported, the figure in most coverage was around 22 to 23%. The published paper leads with 20.4%. Both are real, and the difference is not a correction. It is a choice of estimand, the formal definition of what a trial is measuring.

The treatment-policy estimand asks what happened to everyone randomised, whether or not they kept taking the drug or added a rescue treatment. That is the intention-to-treat principle, and it answers: what does prescribing this do? The trial-product estimand asks what happens to people who take the drug as directed throughout. It gives a larger number because it sets aside the people who stopped.

Neither is dishonest, but they answer different questions, and a comparison between two drugs is only fair if both are quoted on the same basis. When a figure for CagriSema is set against one for another drug, the first thing worth checking is whether the two came from the same kind of estimand.

REDEFINE 2: the same combination in type 2 diabetes

REDEFINE 2 ran the combination in 1,206 adults who had both obesity and type 2 diabetes, randomised 3:1 against placebo across 12 countries for 68 weeks. Weight fell 13.7% against 3.4% on placebo, a difference of 10.4 percentage points ⁵.

The smaller weight effect in people with type 2 diabetes is the usual pattern for this drug class, not a CagriSema-specific finding. On blood sugar the result was large: 73.5% of the CagriSema group reached a glycated haemoglobin of 6.5% or less, against 15.9% on placebo. Gastrointestinal adverse events were reported by 72.5% against 34.4% ⁵.

REIMAGINE: what happened against semaglutide itself

The REIMAGINE programme tested the combination in type 2 diabetes and published in 2026. Its largest trial, REIMAGINE 2, randomised 2,713 people across six arms for 68 weeks and compared the combination directly with semaglutide 2.4 mg. Glycated haemoglobin fell 1.91 percentage points on the combination against 1.75 on semaglutide: a difference of 0.16 points, statistically significant at p=0.0035 ⁶.

That margin is worth sitting with. It is the cleanest published comparison between CagriSema and one of its own two components, and on blood sugar in that population the gap is narrow. Adding cagrilintide clearly adds weight loss; it adds much less to glycaemic control.

The two smaller trials were against placebo. REIMAGINE 1, in 189 people managing diabetes with diet and exercise, cut glycated haemoglobin 1.8 points and weight 13.8% over 40 weeks ⁷. REIMAGINE 3 added the combination to basal insulin in 274 people: glycated haemoglobin fell 2.33 points against 0.66 on placebo, with weight reductions of 10 to 12% and no severe hypoglycaemia reported ⁸.

What the trials found on safety

The dominant signal across both REDEFINE trials is gastrointestinal. In REDEFINE 1, 79.6% of the CagriSema group reported a gastrointestinal adverse event against 39.9% on placebo; in REDEFINE 2 the figures were 72.5% and 34.4% ^{3 5}. Nausea, vomiting, diarrhoea, constipation and abdominal pain were the events recorded, mostly transient and mild to moderate in severity. A rate that high is not unusual for this drug class, and it is a rate in a monitored trial with a protocol-driven dose escalation.

The REIMAGINE trials add the diabetes picture. In REIMAGINE 3, where the combination was added to basal insulin, no severe hypoglycaemia was reported, which is the complication that would most concern a prescriber combining appetite suppression with insulin ⁸. One death occurred in that trial, in the lower-dose group, attributed to malignancy and judged unrelated to treatment.

What the published trials do not yet show is long-term use. REDEFINE 1 ran 68 weeks, and obesity treatment is not a 68-week undertaking; the weight regain seen when GLP-1 drugs stop is a known pattern, and nothing here addresses what happens after this combination is withdrawn.

CagriSema against tirzepatide: what is actually known

The comparison most people want is against tirzepatide, sold as Zepbound for weight management. There is no published head-to-head trial as of September 30, 2026. A trial named REDEFINE 4 has been described as comparing the two, and it has no record in PubMed under that name as of today, so nothing about its result can be reported here.

What can be said is what each drug did in its own trial against its own placebo, and that is a weaker thing than a comparison. Semaglutide 2.4 mg alone produced 14.9% weight loss against 2.4% on placebo in its own 68-week trial ⁹, and CagriSema produced 20.4% against 3.0% in REDEFINE 1, but those are two trials, not one. Different trials enrol different people under different protocols, and weight-loss percentages from separate studies are not interchangeable. The estimand problem above applies with full force here: two numbers from two trials may not even be measuring the same quantity.

When REDEFINE 4 publishes, this article will be updated with its result rather than an inference.

What is sold as CagriSema online

Compounds appear for sale under a drug's name long before any regulator approves it, and CagriSema is no exception. Anything sold as CagriSema as of September 30, 2026 is not the product FDA is reviewing: the application covers a specific fixed-dose combination made to pharmaceutical standards, and nothing sold as a research chemical has been through that.

FDA has sent warning letters to sellers marketing unapproved GLP-1 products, and its compounding guidance treats a drug under active FDA review differently from one in genuine shortage ¹⁰. The practical point for a reader is narrower than the legal one: the trial results on this page describe a manufactured combination at defined doses, given weekly under supervision for 68 weeks, with gastrointestinal adverse events in four out of five participants. None of that transfers to a vial of unknown content.

Our guide to what research-use-only actually means covers the labelling, and the regulatory tracker follows the enforcement.

What to watch in the decision

Three things are worth following. The first is the indication FDA grants, if it grants one: the population in REDEFINE 1 was adults with obesity, or overweight with a complication, and an approval may be narrower than the trial.

The second is tolerability in the label. Nearly 80% of the CagriSema group in REDEFINE 1 had a gastrointestinal adverse event, against 39.9% on placebo, and how the label frames titration and discontinuation will matter in practice ³.

The third is the diabetes question. The REDEFINE and REIMAGINE programmes cover both weight and blood sugar, but the application under review is for weight management; a diabetes indication would be a separate matter.

Our regulatory tracker follows FDA decisions on peptide drugs, and the CagriSema encyclopedia entry carries the trial list and the current status.

Frequently asked questions

Is CagriSema approved?

No. Novo Nordisk filed the application with FDA in December 2025 and the compound is approved nowhere as of September 30, 2026. A decision has been expected in 2026.

How much weight did people lose on CagriSema?

In REDEFINE 1, 20.4% of body weight at 68 weeks against 3.0% on placebo, in 3,417 adults without diabetes. A higher figure of about 22 to 23% also circulates; that comes from a different estimand, which counts only people who kept taking the drug as directed.

Is CagriSema better than Zepbound?

No published trial has compared them. Comparing percentages from separate trials is not a head-to-head result, especially when the two figures may use different estimands.

What is cagrilintide?

An amylin analogue. Amylin is released by the pancreas alongside insulin and slows stomach emptying and signals fullness through a different pathway from GLP-1, which is why combining the two was expected to add rather than overlap.

Did CagriSema beat semaglutide on its own?

On weight, semaglutide alone was a comparator arm in REDEFINE 1. On blood sugar, REIMAGINE 2 found CagriSema beat semaglutide 2.4 mg by 0.16 percentage points of glycated haemoglobin, a result that is statistically significant and clinically small.

Related on Grey Peptides

• CagriSema encyclopedia entry
• Cagrilintide encyclopedia entry
• Semaglutide encyclopedia entry
• Semaglutide vs tirzepatide
• Regulatory tracker

Sources

1. Novo Nordisk. Company announcement: filing of CagriSema with the US Food and Drug Administration for weight management, December 18, 2025. Cited without a link; manufacturers are not linked from this site.
2. Lau, D. C. W. et al. (2021). Once-weekly cagrilintide for weight management in people with overweight and obesity: a multicentre, randomised, double-blind, placebo-controlled and active-controlled, dose-finding phase 2 trial. Lancet, 398(10317), 2160-2172. PMID: 34798060
3. Garvey, W. T. et al. (2025). Coadministered Cagrilintide and Semaglutide in Adults with Overweight or Obesity. N Engl J Med. REDEFINE 1, ClinicalTrials.gov NCT05567796. PMID: 40544433
4. Verma, S. et al. (2026). CagriSema Reduces Blood Pressure in Adults With Overweight or Obesity: REDEFINE 1. Hypertension. PMID: 41328546
5. Davies, M. J. et al. (2025). Cagrilintide-Semaglutide in Adults with Overweight or Obesity and Type 2 Diabetes. N Engl J Med. REDEFINE 2, ClinicalTrials.gov NCT05394519. PMID: 40544432
6. Buse, J. B. et al. (2026). Cagrilintide-semaglutide (CagriSema) versus semaglutide or cagrilintide in people with type 2 diabetes (REIMAGINE 2). Lancet Diabetes Endocrinol. ClinicalTrials.gov NCT06065540. PMID: 42251859
7. Aroda, V. R. et al. (2026). Efficacy and safety of once-weekly cagrilintide-semaglutide (CagriSema) in adults with type 2 diabetes inadequately controlled on diet and exercise (REIMAGINE 1). Lancet Diabetes Endocrinol. ClinicalTrials.gov NCT06323174. PMID: 42251860
8. Rosenstock, J. et al. (2026). Cagrilintide-semaglutide (CagriSema) as an add-on to basal insulin in adults with type 2 diabetes (REIMAGINE 3). Lancet. ClinicalTrials.gov NCT06323161. PMID: 42251856
9. Wilding, J. P. H. et al. (2021). Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med, 384(11), 989-1002. STEP 1. PMID: 33567185
10. U.S. Food and Drug Administration. Compounding and drug shortages. Read September 30, 2026. FDA

Educational information, not medical advice. Each dose in this guide names its source, an approved label or a published study. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. CagriSema is not approved anywhere and is available only through clinical trials; weight and diabetes treatment is a decision for a person and their prescriber.