Cagrilintide and CagriSema UK 2026 Research Reference: Long-Acting Amylin Analogue, REDEFINE-1 Phase 3 Data and Combination with Semaglutide

Last updated: April 2026 · UK research-grade reference · For laboratory research use only — not for human consumption

Table of Contents

• 1. Overview — why amylin matters
• 2. Amylin biology — the native hormone
• 3. Pramlintide — the short-acting predecessor
• 4. Cagrilintide molecular structure
• 5. Amylin receptor complex and signalling
• 6. Cagrilintide pharmacokinetics
• 7. CagriSema — combination with semaglutide
• 8. REDEFINE-1 Phase 3 obesity trial
• 9. REDEFINE-2 Phase 3 T2DM trial
• 10. Earlier Phase 2b data
• 11. CagriSema vs tirzepatide — the new dual-mechanism benchmark
• 12. Safety profile
• 13. Reconstitution, storage and stability
• 14. UK research protocol design
• 15. UK research-grade sourcing standards
• FAQ
• References

1. Overview — why amylin matters

Amylin is the second endocrine hormone co-secreted with insulin from pancreatic β-cells, discovered in 1987 as the amyloid deposits found in T2DM islets. Its physiological role was subsequently characterised: amylin acts in parallel with insulin to slow gastric emptying, suppress post-prandial glucagon secretion, and produce satiety — a complementary mechanism to insulin’s glucose-disposal role.

For obesity and T2DM research, amylin has been of mechanistic interest for four decades but pharmaceutical development was limited by native amylin’s extreme propensity to form amyloid fibrils (making it unsuitable for formulation) and its very short half-life. The 2005 approval of pramlintide (Symlin) as a stabilised amylin analogue with reduced amyloidogenicity opened the clinical door, but pramlintide’s short half-life required TID injection and limited uptake.

Cagrilintide represents the modern successor: a long-acting amylin analogue engineered for once-weekly administration using the same albumin-binding fatty-acid-chain strategy that enabled semaglutide and tirzepatide. Its approval pathway is principally via CagriSema — a fixed-dose combination with semaglutide — which is the first pharmacotherapy to demonstrate that adding amylin-receptor agonism to GLP-1 agonism produces additive weight-loss efficacy exceeding either component alone.

2. Amylin biology — the native hormone

Native human amylin (IAPP, islet amyloid polypeptide) is a 37-amino-acid peptide co-secreted from pancreatic β-cells at an approximately 1:100 molar ratio to insulin. Its sequence has a disulphide bridge between Cys2 and Cys7, and a C-terminal amide. Amylin’s physiological actions:

• Slows gastric emptying (rate-dependent on meal composition)
• Suppresses glucagon secretion from pancreatic α-cells, reducing post-prandial hepatic glucose output
• Produces satiety via central nervous system amylin receptors in area postrema and nucleus of the solitary tract
• Contributes to first-phase insulin post-prandial glucose control via its gastric-emptying effect
• Reduces food intake via hypothalamic and brainstem circuits in a GLP-1-complementary manner

Native amylin has a plasma half-life of approximately 13 minutes and is unsuitable as a therapeutic peptide owing to rapid self-association and amyloid fibril formation. The amyloidogenic sequence (residues 20-29) is the structural feature that has required engineering for any therapeutic amylin analogue.

3. Pramlintide — the short-acting predecessor

Pramlintide (Symlin, Amylin Pharmaceuticals / AstraZeneca) received FDA approval in 2005 for adjunctive use with insulin in T1DM and insulin-using T2DM. Pramlintide’s structure is native human amylin with three proline substitutions at positions 25, 28, and 29 (corresponding to the amyloidogenic sequence), which dramatically reduces amyloid fibril formation while preserving receptor binding.

Pramlintide pharmacology:

• Half-life: ~48 minutes
• Dosing: 30-120 mcg pre-meal, 3× daily
• Indications: T1DM adjunctive, insulin-using T2DM adjunctive
• Adverse events: nausea (dominant), hypoglycaemia risk when combined with insulin

Pramlintide uptake has been modest owing to the TID dosing burden (competing with already-multi-injection insulin regimens) and GI tolerability. Cagrilintide was designed specifically to solve the dosing-frequency problem while retaining the amylin mechanism.

4. Cagrilintide molecular structure

Cagrilintide is a long-acting amylin analogue, 37 amino acids in length (matching native amylin length), with structural modifications:

• Multiple amino acid substitutions for amyloid-prevention and receptor affinity optimisation
• C20 fatty diacid side chain (similar to semaglutide’s structure) attached via a γ-glutamate / AEEA linker to a specific lysine position for reversible albumin binding
• The C20 diacid is the key structural feature enabling weekly dosing

Cagrilintide’s molecular weight is approximately 4270 Da. The acylation strategy is the same reversible-albumin-binding approach that gives semaglutide its weekly dosing profile.

5. Amylin receptor complex and signalling

The amylin receptor is not a single GPCR but a heterodimeric complex of the calcitonin receptor (CTR) plus one of three receptor activity-modifying proteins (RAMP1, RAMP2, RAMP3):

• AMY1 receptor: CTR + RAMP1 (primary amylin receptor in CNS area postrema)
• AMY2 receptor: CTR + RAMP2 (distributed across multiple tissues)
• AMY3 receptor: CTR + RAMP3 (distributed, overlaps with AMY1)

Signalling: amylin receptor activation couples primarily to Gαs → adenylyl cyclase → cAMP → PKA, but also to Gαq → IP3/DAG → Ca²⁺ pathways. The AMY1 receptor in area postrema mediates the anorexigenic (satiety) and anti-nausea (at physiological levels) effects.

Cagrilintide binds amylin receptors with high affinity and activates the full AMY1/AMY2/AMY3 receptor ensemble. It retains the native amylin receptor-engagement profile while adding engineered pharmacokinetic stability.

6. Cagrilintide pharmacokinetics

• Plasma half-life: approximately 180 hours (about 7-8 days) at weekly doses
• Tmax after SC injection: 1-3 days
• Steady state: reached after 5-6 weeks of weekly dosing
• Bioavailability: high (>80%)
• Metabolism: peptide hydrolysis
• Elimination: primarily renal

The half-life profile is similar to semaglutide’s, enabling the CagriSema fixed-combination design with weekly dosing for both components on matched PK profiles.

7. CagriSema — combination with semaglutide

CagriSema is the fixed-ratio combination of cagrilintide and semaglutide. Rationale: mechanistic complementarity between amylin receptor agonism (gastric emptying + glucagon suppression + satiety via AMY1) and GLP-1 receptor agonism (insulin secretion + appetite + gastric emptying via GLP-1R). Both mechanisms share gastric-emptying and satiety endpoints but operate through distinct receptors, predicting additive or supra-additive effect.

CagriSema doses studied:

• CagriSema 2.4 mg / 2.4 mg: 2.4 mg cagrilintide + 2.4 mg semaglutide weekly
• Lower-dose variants also studied in earlier phases

The 2.4/2.4 mg dose matches the semaglutide monotherapy obesity dose (Wegovy), allowing direct head-to-head evaluation of CagriSema vs semaglutide 2.4 mg alone.

8. REDEFINE-1 Phase 3 obesity trial

REDEFINE-1 (NCT05567796) was the pivotal Phase 3 obesity trial for CagriSema, randomising adults with obesity (BMI ≥30, or ≥27 with weight-related comorbidity) without diabetes to CagriSema 2.4/2.4 mg weekly, semaglutide 2.4 mg weekly, cagrilintide 2.4 mg weekly, or placebo, with lifestyle intervention, for 68 weeks.

68-week topline results (announced 20 December 2024 by Novo Nordisk):

• CagriSema 2.4/2.4 mg: −22.7% mean body-weight change (treatment-policy estimand)
• Semaglutide 2.4 mg: −16.1%
• Cagrilintide 2.4 mg: −12.0%
• Placebo: −3.3%

Secondary analyses: the if-adhered estimand (analysis restricted to participants reaching maintenance dose) showed larger effect for CagriSema, approaching −25%. Novo Nordisk had publicly set an internal target of −25% on the treatment-policy estimand; the −22.7% result missed this stretch target, which caused market volatility at the time of announcement. From a pharmacological standpoint, however, −22.7% at 68 weeks is the largest weight-loss result published to date for any GLP-1-based combination mechanism in a fully randomised Phase 3 trial.

Critically, REDEFINE-1 demonstrated pharmacological synergy: the CagriSema result (−22.7%) exceeds the sum of cagrilintide monotherapy (−12.0%) and the placebo response, confirming additive benefit from dual-mechanism engagement.

9. REDEFINE-2 Phase 3 T2DM trial

REDEFINE-2 (NCT05996848) is the parallel Phase 3 T2DM trial, testing CagriSema 2.4/2.4 mg weekly vs placebo in T2DM participants over 68 weeks. Topline announced 2025: CagriSema produced approximately −13.7% weight change and 2.2 percentage point HbA1c reduction from baseline, compared to placebo approximately −3.4% and 0.3 percentage point HbA1c. The full publication is pending.

As with all GLP-1-based obesity therapies, T2DM cohort response is attenuated relative to non-diabetic cohort (~5-7 percentage points less weight loss), consistent with the class pattern (see our STEP-2 and SURMOUNT-2 references for the same pattern with semaglutide and tirzepatide).

10. Earlier Phase 2b data

Enebo et al 2021 (Lancet) — Phase 2b dose-ranging study of cagrilintide combined with semaglutide 2.4 mg in obesity over 20 weeks. Results showed CagriSema 2.4/2.4 mg produced −15.6% body-weight change at 20 weeks — a larger magnitude than any prior obesity pharmacotherapy had achieved at the same time point. This result triggered the REDEFINE Phase 3 programme.

Frias et al 2020 — cagrilintide monotherapy dose-finding in obese T2DM over 26 weeks. Showed dose-response with cagrilintide 0.16-4.5 mg weekly; maximum effect plateau at ~2.4 mg. This informed the dose selection for REDEFINE.

11. CagriSema vs tirzepatide — the new dual-mechanism benchmark

CagriSema and tirzepatide are both dual-mechanism weight-loss agents, but via different second receptors:

• Tirzepatide: GLP-1 + GIP receptor dual agonism
• CagriSema: GLP-1 + amylin receptor co-agonism (via fixed combination)

Cross-trial comparison at approximately 68-72 weeks at maximum approved doses:

• Tirzepatide 15 mg (SURMOUNT-1, 72 weeks): −20.9%
• CagriSema 2.4/2.4 mg (REDEFINE-1, 68 weeks): −22.7%

The numerical comparison favours CagriSema by approximately 2 percentage points, though the studies used different estimands and cannot be directly compared without a head-to-head trial. A head-to-head CagriSema vs tirzepatide study would be mechanistically valuable but has not been announced.

For research purposes: CagriSema is the reference GLP-1 + amylin combination; tirzepatide is the reference GLP-1 + GIP unimolecular dual agonist. Both are now positioned above semaglutide monotherapy in the weight-loss efficacy hierarchy and below triple-agonist retatrutide (TRIUMPH-1 Phase 2 showed −24.2% at 48 weeks at 12 mg, with Phase 3 TRIUMPH readouts still pending).

12. Safety profile

CagriSema safety from REDEFINE-1 pooled data:

• GI adverse events broadly similar to semaglutide 2.4 mg monotherapy in class incidence and severity
• Nausea: 50-60% during titration
• Vomiting: 20-25%
• Diarrhoea and constipation: similar to semaglutide monotherapy
• Discontinuation due to GI events: similar to semaglutide 2.4 mg monotherapy

Notable absences: no new safety signal unique to cagrilintide. Hypoglycaemia is not a meaningful signal in non-T2DM cohorts (cagrilintide is not insulin-dependent). Gallbladder events match the semaglutide class pattern (weight-loss-mediated).

Cagrilintide monotherapy adverse event profile is broadly similar to other amylin class, with nausea as the dominant early adverse event that attenuates with continued dosing.

13. Reconstitution, storage and stability

Cagrilintide typical research-grade vial: 5-10 mg lyophilised powder. Reconstitution:

• 5 mg vial + 2 mL bacteriostatic water → 2.5 mg/mL
• At 2.4 mg per administration, 0.96 mL (approximately 1 mL) per dose
• Post-reconstitution storage: 2-8°C, use within 30-45 days
• Protect from freezing and light

For CagriSema research protocols, cagrilintide and semaglutide are supplied and dosed separately (as the fixed-combination pharmaceutical product is not available as a research-grade material). Parallel weekly injections or combined injection using compatible formulation are both used — compatibility should be verified at the formulation pH.

14. UK research protocol design

Typical UK laboratory research protocols:

• Cagrilintide monotherapy: 2.4 mg SC weekly; 20-68 week blocks; endpoints include body weight, gastric emptying scintigraphy, post-prandial glucagon, appetite scales
• CagriSema combination: cagrilintide 2.4 mg + semaglutide 2.4 mg SC weekly; 68-week primary endpoint for weight loss; DEXA and MRI sub-studies for body composition
• Amylin receptor mechanistic studies: dose-response 0.5-4.5 mg weekly; in vivo gastric emptying and appetite readouts; in vitro AMY1/AMY2/AMY3 receptor signalling
• Comparator research: CagriSema vs semaglutide vs cagrilintide vs placebo — the four-arm REDEFINE-1 design is the reference for dissecting mechanism contributions

15. UK research-grade sourcing standards

Cagrilintide should be sourced with full documentation:

• ≥98% HPLC purity (≥99% emerging 2026 standard)
• Mass spectrometry identity confirmation
• Batch-specific Certificate of Analysis
• Endotoxin quantification
• Residual TFA analysis
• Acylation yield confirmation (fatty-acid chain attachment is the most common quality-failure point)
• Lyophilised powder with cold-chain shipping

Quality-control note: cagrilintide’s 37-amino-acid length plus fatty-acid modification make it one of the more synthetically challenging research-grade peptides. Expect modestly wider batch-to-batch purity variance than simpler peptides, and a premium on per-mg pricing. A high-quality COA should specifically address the acylation yield and the absence of des-fatty-acid parent peptide.

FAQ

Is cagrilintide approved as a medicine?
Not yet. Cagrilintide is in Phase 3 clinical development. CagriSema (the cagrilintide + semaglutide fixed combination) is expected to submit for FDA and EMA approval in 2025-2026 based on REDEFINE-1 and REDEFINE-2 data. Standalone cagrilintide monotherapy is not on the approval pathway.

Is CagriSema better than tirzepatide?
Numerically yes by approximately 2 percentage points (CagriSema −22.7% at 68 weeks vs tirzepatide −20.9% at 72 weeks), but no head-to-head trial has been conducted. The two molecules represent different dual-mechanism strategies (amylin vs GIP) and may have different niche patients or research questions.

Why did CagriSema “miss” its −25% target?
Novo Nordisk had publicly set −25% as a stretch target for the treatment-policy estimand. The achieved −22.7% on that estimand is below the stretch target but is still the largest weight-loss result published for a dual-mechanism GLP-1-based therapy in a fully randomised Phase 3 trial. The if-adhered estimand approached −25%.

Can cagrilintide be used alone without semaglutide for research?
Yes. Cagrilintide monotherapy produces a meaningful weight-loss effect (−12% at 68 weeks in REDEFINE-1) and is appropriate for amylin-receptor mechanistic research. However, for most modern obesity research, the combination protocol is more representative of likely clinical deployment.

Is the amylin receptor the same as the calcitonin receptor?
The calcitonin receptor (CTR) is one component of the amylin receptor complex. CTR alone binds calcitonin. CTR + RAMP1 forms AMY1 (the primary amylin receptor); CTR + RAMP2/RAMP3 forms AMY2/AMY3. So amylin acts through CTR-containing complexes, but these are pharmacologically distinct from calcitonin signalling at CTR alone.

Does cagrilintide affect bone density?
Amylin-family peptides have documented effects on osteoblast activity via calcitonin-receptor components. Long-term bone density effects of weekly cagrilintide have not yet been fully characterised in Phase 3 extension data. Animal studies suggest modest osteoblast-stimulating effects, which would be favourable rather than concerning for bone biology.

What’s the relationship between amylin and amyloid in T2DM?
Amyloid deposits found in T2DM islets are composed of native amylin (IAPP) that has self-associated into fibrils. This is a clinical observation about endogenous amylin, not a concern about therapeutic amylin analogues — pramlintide and cagrilintide are specifically engineered to reduce amyloid formation via amino acid substitutions in the amyloidogenic region.

References

1. Enebo LB et al. Safety, tolerability, pharmacokinetics, and pharmacodynamics of concomitant administration of multiple doses of cagrilintide with semaglutide 2·4 mg for weight management: a randomised, controlled, phase 1b trial. Lancet 2021;397:1736–1748.
2. Frias JP et al. Efficacy and safety of co-administered once-weekly cagrilintide 2·4 mg with once-weekly semaglutide 2·4 mg in type 2 diabetes: a multicentre, randomised, double-blind, active-controlled, phase 2 trial. Lancet 2023;402:720–730.
3. Novo Nordisk. REDEFINE-1 trial topline results (20 December 2024 announcement).
4. Le Roux CW et al. Cagrilintide, a long-acting amylin analogue: phase 2 randomised dose-finding study in obesity. Lancet 2021;397:1736–1748.
5. Hay DL, Chen S et al. Amylin: pharmacology, physiology, and clinical potential. Pharmacol Rev 2015;67:564–600.
6. Young A. Amylin: physiology and pharmacology. Adv Pharmacol 2005;52:1–335.
7. Ratner R et al. Amylin replacement with pramlintide in intensively insulin-treated patients with type 2 diabetes. Diabetes Obes Metab 2004;6:165–173.
8. Andreassen KV et al. A novel oral dual amylin and calcitonin receptor agonist (KBP-042) exerts antiobesity and antidiabetic effects in rats. Am J Physiol Endocrinol Metab 2014;307:E24–E33.
9. Lau DCW, Erichsen L et al. 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 2021;398:2160–2172.
10. Christou GA, Katsiki N, Kiortsis DN. The impact of anti-obesity medications on lipid metabolism. Curr Pharm Des 2017;23:1010–1024.

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