REDEFINE Trial: CagriSema vs Semaglutide Alone
CagriSema
22.7% mean weight loss
In the REDEFINE 1 trial, CagriSema produced 22.7% weight reduction at 68 weeks in adults with obesity, the largest weight loss reported for any injectable peptide combination in Phase 3.
Garvey et al., New England Journal of Medicine, 2025
Garvey et al., New England Journal of Medicine, 2025
View as imageCagriSema combines two peptides that suppress appetite through different brain pathways: semaglutide (a GLP-1 receptor agonist) and cagrilintide (a long-acting amylin analog). The REDEFINE trials, published in the New England Journal of Medicine in 2025, tested whether pairing these mechanisms would produce meaningfully greater weight loss than either drug alone.[1] The answer was yes. The cagrilintide article covers the amylin component in detail, and the CagriSema combination article explains the rationale for dual targeting. This article focuses on what the Phase 3 data actually showed.
Key Takeaways
- REDEFINE 1 enrolled 3,400 adults with obesity but without diabetes; CagriSema produced 20.4% weight loss vs 3.0% with placebo at 68 weeks (22.7% in the on-treatment estimand) (Garvey et al., NEJM, 2025)
- REDEFINE 2 enrolled 1,206 adults with obesity and type 2 diabetes; CagriSema produced 13.7% weight loss vs 3.4% with placebo, plus 73.5% of patients achieved HbA1c at or below 6.5% (Davies et al., NEJM, 2025)
- 40.4% of adherent patients in REDEFINE 1 lost 25% or more of their body weight, a threshold approaching bariatric surgery outcomes
- Gastrointestinal side effects affected 79.6% of CagriSema patients vs 39.9% on placebo, though most were mild to moderate and transient
- CagriSema also reduced systolic blood pressure by 5-7 mmHg more than placebo in a prespecified analysis (Verma et al., Hypertension, 2026)
- A meta-analysis of all CagriSema trials confirmed superiority over semaglutide monotherapy with a pooled weight loss difference of approximately 5-7 percentage points (Gadelmawla et al., 2026)
What CagriSema Is
CagriSema is a fixed-dose combination of two Novo Nordisk peptides delivered in a single once-weekly subcutaneous injection. The semaglutide component (2.4 mg) is the same GLP-1 receptor agonist used in Wegovy. The cagrilintide component (2.4 mg) is a long-acting analog of human amylin, a peptide co-secreted with insulin from pancreatic beta cells after meals.
Kruse and colleagues published the development of cagrilintide in 2021, describing how they engineered a fatty acid-acylated amylin analog with a half-life of approximately 160 hours (nearly 7 days), compared to native amylin's half-life of roughly 13 minutes.[2] That pharmacokinetic transformation made once-weekly dosing possible.
The two peptides suppress appetite through parallel but distinct brain circuits. Semaglutide activates GLP-1 receptors in the hypothalamus and hindbrain. Cagrilintide activates amylin receptors (calcitonin receptor/RAMP complexes) in the area postrema and nucleus tractus solitarius. Carvas and colleagues confirmed in 2025 that cagrilintide reduces body weight specifically through brain amylin receptors 1 and 3, establishing the central mechanism rather than a peripheral effect on gastric emptying.[3]
REDEFINE 1: Adults with Obesity, No Diabetes
The REDEFINE 1 trial was a Phase 3a, randomized, double-blind, placebo-controlled trial enrolling 3,400 adults with a BMI of 30 or above (or 27+ with at least one weight-related comorbidity) who did not have type 2 diabetes.[1]
Weight Loss Results
The primary endpoint was percentage change in body weight from baseline to week 68:
- CagriSema: -20.4% (treatment policy estimand, accounting for all randomized patients regardless of adherence)
- Placebo: -3.0%
- Difference: -17.4 percentage points (p < 0.001)
When analyzed using the trial product estimand (accounting for full adherence to treatment), CagriSema produced 22.7% mean weight loss. This is the largest weight reduction reported in any Phase 3 trial of an injectable peptide combination.
Categorical Weight Loss
The percentage of patients achieving specific weight loss thresholds (trial product estimand):
- 10% or more weight loss: 79.8% on CagriSema vs 16.2% on placebo
- 15% or more: 66.5% vs 7.2%
- 20% or more: 53.3% vs 3.0%
- 25% or more: 40.4% vs 1.4%
The 25% threshold is clinically meaningful because it approaches the weight loss typically seen after bariatric surgery procedures. Until CagriSema, no pharmacological intervention had achieved this threshold in more than a third of participants. The question of how much weight you can lose on semaglutide alone provides context for the comparison.
REDEFINE 2: Adults with Obesity and Type 2 Diabetes
REDEFINE 2 enrolled 1,206 adults with BMI of 27 or above who also had type 2 diabetes. Davies and colleagues published the results simultaneously in the NEJM.[4]
Weight and Glycemic Results
- Weight loss: -13.7% with CagriSema vs -3.4% with placebo (difference: -10.4 percentage points, p < 0.001)
- HbA1c at or below 6.5%: 73.5% on CagriSema vs 15.9% on placebo
- HbA1c below 5.7% (normal range): 38.8% on CagriSema vs 2.6% on placebo
Weight loss in the diabetes population was lower than in REDEFINE 1, consistent with a pattern seen across all GLP-1 agonist trials: people with type 2 diabetes consistently lose less weight than those without diabetes on the same drug. The mechanism likely involves insulin resistance and altered incretin signaling.
The glycemic results were striking. Nearly three-quarters of patients on CagriSema achieved an HbA1c that no longer meets the diagnostic threshold for diabetes, and more than a third reached a level considered normal. This raises the question of whether CagriSema could functionally achieve diabetes remission in a substantial proportion of patients, though long-term data beyond 68 weeks are needed to know if these effects persist.
The REDEFINE 2 population had a mean baseline HbA1c of approximately 8.0%, indicating moderately uncontrolled diabetes. Mean diabetes duration was roughly 10 years. Most participants were on one or two oral antidiabetic medications at enrollment. The magnitude of HbA1c reduction (approximately 1.5 percentage points more than placebo) exceeded what semaglutide alone typically achieves in diabetes trials, suggesting the amylin component contributes to glucose control independently of its weight loss effects. Amylin suppresses glucagon secretion, slows gastric emptying, and reduces postprandial glucose spikes through mechanisms distinct from GLP-1's insulin-stimulating effects.
How CagriSema Compares to Semaglutide Alone
The REDEFINE trials did not include a semaglutide-only comparator arm. However, the Phase 2 trial by Frias and colleagues in 2023 did directly compare CagriSema to semaglutide 2.4 mg alone in patients with type 2 diabetes. Over 32 weeks, CagriSema produced 15.6% weight loss versus 5.1% with semaglutide alone.[5]
Gadelmawla and colleagues conducted a systematic review and meta-analysis in 2026, pooling data across all CagriSema randomized controlled trials with GRADE assessment. The analysis confirmed CagriSema's superiority over both semaglutide monotherapy and placebo, with the combination producing approximately 5-7 percentage points more weight loss than semaglutide alone.[6]
For context, semaglutide 2.4 mg alone (Wegovy) produced approximately 15-17% weight loss in the STEP trials. CagriSema's 20-23% range represents a meaningful step forward, though tirzepatide's dual mechanism produced similar weight loss (up to 22.5% in the SURMOUNT trials) through a different combination approach (GLP-1 + GIP rather than GLP-1 + amylin).
Dutta and colleagues conducted a systematic review and meta-analysis in 2024, pooling data from all available CagriSema trials including the Phase 2 dose-ranging studies. Their analysis found that cagrilintide alone at the 2.4 mg dose produced approximately 10-11% weight loss over 26 weeks, and that the combination with semaglutide produced additive or slightly super-additive weight reduction, consistent with the two drugs working through independent pathways rather than simply doubling the same signal.[7] The earlier Phase 2 dose-finding trial by Lau and colleagues in 2021 had tested cagrilintide alone at multiple doses (0.3 mg to 4.5 mg weekly) versus placebo, establishing the 2.4 mg dose as the best balance of efficacy and tolerability for the combination product.[11]
Safety Profile
Gastrointestinal side effects dominated the adverse event profile in both REDEFINE trials.
In REDEFINE 1, 79.6% of CagriSema patients experienced at least one GI event versus 39.9% on placebo. The most common were nausea (46.0% vs 13.3%), diarrhea (24.5% vs 12.0%), vomiting (22.1% vs 4.4%), and constipation (18.1% vs 5.9%). Most events were mild to moderate in severity and occurred during the dose-escalation phase, tapering with continued use.[1]
Clayton and colleagues pooled safety data across the clinical development program in a 2022 analysis. Serious adverse events were infrequent and not clearly attributable to the drug combination. No signal for pancreatitis, thyroid cancer, or major cardiovascular events was detected, though the 68-week trial duration limits conclusions about rare or slow-developing events.[7]
The early Phase 1b data from Enebo and colleagues in 2021 established that cagrilintide and semaglutide do not have problematic pharmacokinetic interactions when co-administered, and that the GI side effect profile of the combination is not dramatically worse than semaglutide alone at the same dose.[8]
Blood Pressure Effects
Verma and colleagues published a prespecified analysis of REDEFINE 1 blood pressure data in 2026. CagriSema reduced systolic blood pressure by 5-7 mmHg more than placebo at week 68, an effect that was partially but not entirely explained by weight loss. The finding suggests the amylin and GLP-1 pathways may have direct vascular effects beyond their impact on body weight.[9]
How It Works: Preclinical Mechanism
Jacobsen and colleagues published detailed preclinical data in Nature Metabolism in 2025, showing that CagriSema drives weight loss in rats primarily by reducing energy intake rather than increasing energy expenditure. The combination preserved resting metabolic rate better than caloric restriction alone, addressing one of the major concerns about rapid weight loss: metabolic adaptation, where the body lowers its energy expenditure to resist further weight loss.[10]
This metabolic preservation may explain why CagriSema produces greater weight loss than either component alone. Semaglutide reduces appetite through one circuit; cagrilintide reduces appetite through a separate circuit. But the combination may also produce a qualitatively different metabolic response than simply adding two appetite suppressants together. The article on combination peptide therapy explores this concept more broadly.
What Remains Unknown
The REDEFINE trials establish efficacy and short-term safety. Several important questions remain open.
Weight regain after stopping: The GLP-1 agonist field has consistently shown that patients regain weight after discontinuation. Whether the amylin component changes this trajectory is unknown.
Muscle loss: Rapid weight loss on GLP-1 agonists produces measurable lean mass reduction. REDEFINE did not report body composition data. The concern is whether 20%+ weight loss accelerates sarcopenia, particularly in older patients. The article on semaglutide body composition and the broader discussion of muscle and skin effects of rapid weight loss cover this gap.
Cardiovascular outcomes: No dedicated cardiovascular outcomes trial has been completed for CagriSema. Semaglutide alone has demonstrated cardiovascular benefit in the SELECT trial, but whether cagrilintide adds to or simply preserves that benefit is unproven.
Cost and access: Novo Nordisk has not disclosed pricing. If CagriSema is priced above Wegovy ($1,300/month), access will be a significant barrier. The broader question of GLP-1 drug cost applies here.
Head-to-head comparisons: REDEFINE did not directly compare CagriSema to tirzepatide (Mounjaro/Zepbound), the current market leader in weight loss efficacy. Indirect comparisons suggest similar overall weight loss, but the mechanisms differ (GLP-1/amylin vs GLP-1/GIP), and the side effect profiles, metabolic effects, and long-term outcomes may diverge. A head-to-head trial would be the only way to settle the question of which approach is superior, and neither manufacturer has announced plans for one.
Duration of treatment: Like all current anti-obesity medications, CagriSema appears to require indefinite use. The STEP 1 extension trial for semaglutide showed two-thirds of lost weight was regained within one year of stopping treatment. Whether the amylin component produces more durable appetite suppression or metabolic changes that persist after discontinuation is a critical question that the current data cannot answer. The relationship between liraglutide and semaglutide in the GLP-1 evolution provides context for how these drugs iterate over time.
The Bottom Line
The REDEFINE trials established CagriSema as the most effective injectable peptide combination for weight loss in Phase 3 testing. In adults without diabetes, the drug produced 22.7% weight loss at 68 weeks with 40% of adherent patients losing 25% or more of their body weight. In adults with type 2 diabetes, 73.5% achieved HbA1c below the diabetes diagnostic threshold. GI side effects affected approximately 80% of patients but were mostly mild and transient. Key unknowns include long-term weight maintenance, body composition effects, and cardiovascular outcomes.