Amylin Analogues: The Next Frontier in Weight Loss After GLP-1s

Last Updated: March 2025

22.7% average body weight reduction. That's what CagriSema—Novo Nordisk's combination of cagrilintide and semaglutide—delivered in the REDEFINE 1 Phase 3 trial published in late 2024, per data presented at the American Diabetes Association Scientific Sessions. While GLP-1 receptor agonists like Wegovy and Zepbound dominate obesity treatment headlines, amylin analogues represent a mechanistically distinct pathway that's proving unexpectedly potent. Cagrilintide doesn't just tweak insulin signaling—it targets the amylin receptor complex that controls meal-termination signals and gastric emptying at a neurological level GLP-1s don't fully address.

Amylin is a 37-amino acid peptide co-secreted with insulin from pancreatic beta cells. In people with obesity and type 2 diabetes, amylin levels are chronically low or dysfunctional. The hormone works primarily in the area postrema of the brainstem, triggering satiety independent of leptin or GLP-1 pathways. Pramlintide, approved by the FDA in 2005 for diabetes, was the first synthetic amylin analogue—but its short half-life and thrice-daily injection schedule made it clinically impractical for obesity. Cagrilintide extends amylin's half-life to approximately 7 days through structural modifications that reduce renal clearance while maintaining receptor affinity.

The REDEFINE 1 trial enrolled 3,400 participants with a baseline BMI ≥30 kg/m² (or ≥27 kg/m² with comorbidities) across 16 countries. Participants received either CagriSema (cagrilintide 2.4 mg + semaglutide 2.4 mg), semaglutide 2.4 mg alone, or placebo over 68 weeks. The combination arm hit 22.7% mean weight reduction versus 16.1% for semaglutide monotherapy and 2.3% for placebo. Critically, 46.8% of CagriSema patients achieved ≥25% weight loss—a threshold previously seen only in bariatric surgery cohorts. Novo Nordisk submitted the New Drug Application to the FDA in February 2025.

How Amylin Differs From GLP-1

GLP-1 agonists slow gastric emptying and reduce appetite via the hypothalamus and brainstem. Amylin analogues operate through distinct neuronal circuits. According to a 2023 review in Diabetes, Obesity and Metabolism, "amylin's effects on meal size termination are preserved even in leptin-resistant states, suggesting a unique therapeutic advantage in severe obesity where leptin signaling is impaired."

Cagrilintide binds to the calcitonin receptor-receptor activity-modifying protein (CTR-RAMP) complex. This binding inhibits glucagon secretion more directly than GLP-1s, which modulate glucagon indirectly through insulin. In a head-to-head 26-week trial published in The Lancet (2022), cagrilintide 4.5 mg produced 10.8% weight loss compared to 9.0% with liraglutide 3.0 mg—despite liraglutide being a best-in-class GLP-1 at obesity doses.

The mechanistic synergy between amylin and GLP-1 explains CagriSema's outsized results. Amylin slows gastric emptying through vagal nerve pathways, while GLP-1 works on L-cells in the gut and central appetite circuits. When combined, the dual pathway creates what researchers call "complementary anorexigenic signaling"—essentially hitting satiety from two neurological angles that don't overlap functionally.

Monotherapy Data: Cagrilintide Alone

Before CagriSema's combination data emerged, researchers tested cagrilintide as monotherapy. A Phase 2 dose-ranging trial in 2021 (University of Copenhagen) assigned 706 participants to cagrilintide doses from 0.3 mg to 4.5 mg weekly. At the highest dose, participants lost 10.8% body weight over 26 weeks versus 3.2% on placebo. Nausea rates were dose-dependent: 52.1% at 4.5 mg versus 18.3% at 0.3 mg.

Those numbers positioned cagrilintide slightly below semaglutide 2.4 mg (which delivered 14.9% weight loss in the STEP 1 trial over 68 weeks). But monotherapy wasn't the endgame. Novo Nordisk's strategic pivot to combination therapy acknowledged a reality: single-target drugs have biological ceilings. The company had already seen this with oral semaglutide (Rybelsus), which plateaued around 5-6% weight loss due to absorption limitations.

REDEFINE 1 Secondary Endpoints

Weight loss was the primary endpoint, but cardiometabolic markers told a broader story. CagriSema reduced HbA1c by 1.8 percentage points in participants with type 2 diabetes (n=1,240 subgroup), compared to 1.4 points for semaglutide alone. Systolic blood pressure dropped 7.4 mmHg versus 5.1 mmHg. Triglycerides decreased 28.3% in the combination arm versus 19.7% for semaglutide monotherapy.

Waist circumference—a proxy for visceral adiposity—decreased by 18.1 cm with CagriSema versus 13.2 cm with semaglutide. That differential matters. Visceral fat correlates more strongly with cardiovascular risk than subcutaneous fat. A 2023 meta-analysis in Obesity Reviews found that each 1 cm reduction in waist circumference associates with a 2.1% decrease in major adverse cardiovascular events (MACE) over 10 years.

Endpoint	CagriSema	Semaglutide 2.4mg	Placebo
Mean weight loss (%)	22.7%	16.1%	2.3%
≥25% weight loss (% of patients)	46.8%	23.4%	1.2%
HbA1c reduction (pp, diabetic subgroup)	-1.8	-1.4	-0.3
Systolic BP reduction (mmHg)	-7.4	-5.1	-1.1
Waist circumference reduction (cm)	-18.1	-13.2	-3.4

Adverse Events and Tolerability

Nausea remains the Achilles heel of incretin-based therapies, and adding amylin doesn't help. In REDEFINE 1, 52.9% of CagriSema patients reported nausea versus 44.2% on semaglutide alone. Vomiting occurred in 31.7% versus 24.1%. Discontinuation rates due to gastrointestinal adverse events were 8.4% for the combination versus 5.2% for semaglutide monotherapy.

These aren't trivial numbers, but they're also not trial-ending. The STEP 1 trial (semaglutide for obesity) saw 7.0% discontinuation due to GI issues. Tirzepatide's SURMOUNT-1 trial reported 6.2%. What matters is whether the additional efficacy justifies the additional side effect burden. For a patient losing an extra 6.6 percentage points of body weight, many will tolerate more nausea—especially when dose titration protocols can mitigate peak severity.

One notable finding: hypoglycemia rates were not significantly elevated in CagriSema versus semaglutide alone (3.1% versus 2.8% in non-diabetic participants). Amylin's glucagon suppression is glucose-dependent, reducing hypo risk compared to sulfonylureas or insulin.

Competitive Landscape

Novo Nordisk isn't alone in developing amylin-based therapies, though they're furthest ahead. Zealand Pharma is testing petrelintide, another long-acting amylin analogue, in Phase 2 trials. Early data from a 2024 dose-finding study showed 8.6% weight loss at 20 weeks with petrelintide 5 mg weekly—respectable, but not combination-level.

Eli Lilly, which dominates the dual GIP/GLP-1 space with tirzepatide (Zepbound, Mounjaro), hasn't publicly disclosed amylin programs. That's strategic. Tirzepatide already delivers 20.9% mean weight loss in SURMOUNT-1 (72 weeks), rivaling CagriSema's results through a different dual-mechanism approach. Adding a third peptide (amylin) to GIP/GLP-1 would likely increase manufacturing complexity and side effects without proportional benefit.

Drug/Combination	Mechanism	Mean Weight Loss	Trial Duration
CagriSema	Amylin + GLP-1	22.7%	68 weeks
Tirzepatide 15mg	GIP + GLP-1	20.9%	72 weeks
Semaglutide 2.4mg	GLP-1	14.9%	68 weeks
Cagrilintide 4.5mg	Amylin	10.8%	26 weeks

Regulatory and Market Timeline

FDA review timelines for new molecular entities average 10-12 months under standard pathways. CagriSema could see approval by early 2026 if the agency doesn't request additional cardiovascular outcomes data. The NDA submission included REDEFINE 1 plus supportive Phase 2 data, but no dedicated CVOT (cardiovascular outcomes trial). That's notable. Semaglutide required the SELECT trial (17,604 participants, 3.3 years) to demonstrate CV risk reduction before securing broad insurance coverage.