Cagrilintide and semaglutide are not competitors — they are complements. They target completely different receptor systems (amylin vs GLP-1), activate different brain regions, and when combined, produce weight loss that exceeds what either achieves alone.
This comparison breaks down what each does, how they differ, and why their combination (CagriSema) may represent the next leap in obesity pharmacotherapy.
Side-by-side evidence
Outcomes where both peptides have published data. Each cell carries two grades: clinical evidence (human-RCT depth for this specific outcome) and community evidence (real-world adoption). How we grade evidence.
| Outcome | Cagrilintide | Semaglutide |
|---|---|---|
| Body weight reduction (monotherapy) | Clinical:Moderate Community:Strong ~10-12% weight loss at 26 weeks in Phase 2 trials as monotherapy. | Clinical:Strong Community:Moderate ~14.9% weight loss in STEP 1 over 68 weeks at 2.4 mg weekly. |
| Body weight reduction (combination) | Clinical:Moderate Community:Strong Combined with semaglutide (CagriSema) drove ~22.7% weight loss at 32 weeks. | Clinical:Strong Community:Moderate Pairs well — semaglutide handles GLP-1 axis while cagrilintide adds amylin-driven satiety. |
| Glycemic control | Clinical:Preliminary Community:Strong Modest HbA1c effect in early trials; not the primary use case. | Clinical:Strong Community:Moderate FDA-approved for type 2 diabetes; large HbA1c reductions across SUSTAIN program. |
| Side effect burden | Clinical:Moderate Community:Strong Nausea and GI symptoms common during titration; generally well tolerated. | Clinical:Strong Community:Moderate GI symptoms in 30-50% of subjects during titration; usually transient. |
Quick Comparison
| Feature | Cagrilintide | Semaglutide |
|---|---|---|
| Drug class | Long-acting amylin analog | GLP-1 receptor agonist |
| Primary receptors | AMY1R, AMY3R | GLP-1R |
| Dosing | 2.4 mg weekly | 2.4 mg weekly |
| Half-life | ~160 hours | ~7 days |
| Weight loss (monotherapy) | 9-11% (Phase 2, 26 wk) | 15-17% (STEP trials, 68 wk) |
| Weight loss (combined) | 22.7% (CagriSema, 68 wk) | — |
| FDA status | Investigational | Approved |
| Key brain regions | Area postrema, NTS | Hypothalamus, NTS |
| Gastric emptying | Slows | Slows |
| Glucagon effect | Suppresses postprandial | Suppresses (glucose-dependent) |
Mechanism: Two Separate Pathways
This is the critical distinction. Cagrilintide and semaglutide are not two versions of the same thing — they work through fundamentally different receptor systems.
Cagrilintide: The Amylin Pathway
Cagrilintide is an acylated analog of human amylin with a ~160-hour half-life (native amylin lasts ~15 minutes). It activates amylin receptors 1 and 3 (AMY1R/AMY3R) — heterodimers of the calcitonin receptor with receptor activity-modifying proteins (Lau et al., 2021).
Primary action sites: area postrema and nucleus of the solitary tract (NTS) in the brainstem. These regions process satiety signals from the gut and produce the "I've had enough" feeling during and after meals.
Semaglutide: The GLP-1 Pathway
Semaglutide is a GLP-1 receptor agonist with 94% homology to native GLP-1 and a ~7-day half-life achieved through C18 fatty acid acylation and DPP-4 resistance (Muller et al., 2021).
Primary action sites: hypothalamus (arcuate nucleus, paraventricular nucleus) and NTS. These regions regulate energy homeostasis, hunger/satiety set points, and reward-related eating behavior.
Why the Distinction Matters
The overlap at the NTS is notable — both pathways converge there. But cagrilintide engages the area postrema (which semaglutide does not primarily target) while semaglutide engages the hypothalamus (which cagrilintide does not primarily target). The result is broader brain coverage of appetite regulation circuits than either agent alone.
Weight Loss: Monotherapy Comparison
Comparing these head-to-head as monotherapies requires some context, because the pivotal trials differed in duration and design.
Cagrilintide Monotherapy (Phase 2)
The Lau et al. (2021) trial tested cagrilintide at 0.3-4.5 mg weekly for 26 weeks in 706 adults:
| Dose | Weight Loss | >=5% Threshold | >=10% Threshold |
|---|---|---|---|
| 2.4 mg | -9.1% | 67% | 42% |
| 4.5 mg | -10.8% | 75% | 51% |
| Liraglutide 3.0 mg (control) | -9.0% | 67% | 38% |
Semaglutide Monotherapy (Phase 3)
The STEP 1 trial tested semaglutide 2.4 mg weekly for 68 weeks in 1,961 adults:
- Mean weight loss: -14.9%
-
=10% threshold: ~70%
-
=15% threshold: ~54%
-
=20% threshold: ~32%
Important caveat: The semaglutide trial was 68 weeks versus only 26 weeks for cagrilintide. Weight loss with GLP-1 agonists continues accumulating through week 60+. A fair comparison would require same-duration data, which does not exist for monotherapy. Cagrilintide at 26 weeks may not have reached its full weight loss potential.
That said, semaglutide's absolute numbers at any timepoint comparison are higher. As monotherapy, semaglutide appears to be the more potent weight loss agent.
The Combination: CagriSema
The real clinical story is not monotherapy versus monotherapy — it is the combination.
REDEFINE 1 Results (Phase 3)
The landmark trial randomized 3,417 adults to CagriSema 2.4/2.4 mg, semaglutide 2.4 mg alone, cagrilintide 2.4 mg alone, or placebo for 68 weeks (Aronne et al., 2025):
| Outcome | CagriSema | Semaglutide alone | Cagrilintide alone | Placebo |
|---|---|---|---|---|
| Mean weight loss | 22.7% | ~15-17% | ~9-11% | ~2% |
| >=20% weight loss | 60% | ~30-35% | — | — |
| >=30% weight loss | 23% | ~10% | — | — |
The combination significantly outperformed either component alone. The additive effect validates the biological hypothesis: amylin and GLP-1 engage overlapping but distinct neural circuits, and activating both produces a synergistic response that neither achieves independently.
REDEFINE 2 (Type 2 Diabetes)
In patients with T2D, CagriSema produced significant weight loss alongside glycemic improvements (HbA1c reduction), outperforming the individual components (Lingvay et al., 2025).
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