Cagrilintide

What amylin does. Amylin is co-secreted with insulin from the pancreatic beta cell after a meal. It slows gastric emptying, suppresses glucagon and - the part that matters here - signals satiety through receptors in the area postrema. It is a genuinely separate satiety pathway from GLP-1, which is why combining the two is more than a dose increase [5][6]. Native amylin aggregates and is short-lived; pramlintide, the first analogue, required three-times-daily dosing. Cagrilintide is acylated for a week-long half-life [7].

On its own. The phase 2 trial randomised 706 adults with overweight or obesity to cagrilintide 0.3-4.5 mg, liraglutide 3.0 mg, or placebo for 26 weeks. Weight reductions ran from 6.0% to 10.8% across cagrilintide doses against 3.0% on placebo - and 4.5 mg beat liraglutide 3.0 mg, 10.8% against 9.0%. Gastrointestinal adverse events affected 41-63% against 32% on placebo, primarily nausea [1]. For a mechanism nobody had taken seriously as a standalone weight drug, that is a strong result.

As CagriSema. The phase 1b trial established that the two peptides could be given together, that cagrilintide's half-life of 159-195 hours matched semaglutide's, and that neither affected the other's pharmacokinetics [7]. REDEFINE 1 then randomised 3417 adults without diabetes to cagrilintide-semaglutide 2.4 mg each, semaglutide alone, cagrilintide alone, or placebo. The combination gave -20.4% at 68 weeks against -3.0% on placebo, and beat placebo on every threshold up to 30% weight loss [2]. REDEFINE 2, in 1206 people with type 2 diabetes, gave -13.7% against -3.4%, with 73.5% reaching HbA1c of 6.5% or less against 15.9% [3]. REIMAGINE 2 compared the combination against each component in type 2 diabetes [8].

Blood pressure. A prespecified analysis of REDEFINE 1 found 63.0% of the CagriSema group reaching blood pressure targets against 32.0% on placebo, and 39.6% of those on antihypertensive medication reducing or stopping it against 18.8% [9].

The context. Eloralintide's phase 2 trial reached 20% weight loss on amylin agonism alone [4], which suggests cagrilintide's monotherapy result was not the ceiling of the mechanism - and that the amylin class is going to be a real competitor, not just a combination partner.

Amylin receptors are formed when the calcitonin receptor associates with receptor activity-modifying proteins, and they are concentrated in the area postrema and nucleus tractus solitarius - brainstem regions outside the blood-brain barrier that sense circulating satiety signals. Amylin agonism there produces meal-related satiation, a different signal from GLP-1's, which is why the two combine additively rather than redundantly [5].

Cagrilintide is an acylated analogue engineered against amylin's natural tendency to aggregate, with a fatty diacid for albumin binding. Its half-life of 159-195 hours was deliberately matched to semaglutide's so that both can be delivered from one weekly injection [7].

There is a practical corollary worth noting. Because amylin acts on a different pathway, its adverse effects are not simply more of GLP-1's - nausea is common but the profile differs, and in eloralintide's trial fatigue emerged as a dose-related effect that is not prominent with incretins [4].

A weekly subcutaneous injection. The commercial development is as CagriSema, a fixed-dose co-formulation of cagrilintide 2.4 mg and semaglutide 2.4 mg in one pen - made possible by matching the two half-lives [7].

Gastrointestinal effects dominate, as across the field. In the phase 2 monotherapy trial they affected 41-63% of cagrilintide groups against 32% on placebo, primarily nausea at 20-47% against 18%; permanent discontinuation was driven by 30 adverse events across the whole trial [1]. In REDEFINE 1, the combination produced gastrointestinal adverse events in 79.6% against 39.9% on placebo [2]; in REDEFINE 2, 72.5% against 34.4% [3].

In the phase 1b combination study, 207 of the adverse events recorded - 37% of the total - were gastrointestinal, and they occurred in nearly every participant on both arms [7].

What is not known. No cardiovascular outcome trial has reported for cagrilintide or for CagriSema. Amylin agonism is a newer mechanism in humans than GLP-1 agonism, with correspondingly less long-term data; the largest body of prior human experience is with pramlintide in type 1 and type 2 diabetes. Long-term effects on lean mass, bone and the brainstem targets are not characterised.

The class perioperative gastric-emptying precaution applies, and applies more strongly to a combination [10][11].

The important interaction is the intended one. Cagrilintide and semaglutide do not affect each other's pharmacokinetics [7], and combined they produce substantially more weight loss than either alone [2][8].

Beyond that, no dedicated interaction studies have been published. Delayed gastric emptying affects oral drug absorption, and the combination's blood pressure effect means antihypertensive doses often need revisiting - in REDEFINE 1, 39.6% of treated participants on antihypertensives reduced or stopped them [9].