Only two of the comparisons that get argued about rest on randomised head-to-head evidence, and the rest are cross-trial guesswork. Inside REDEFINE 1 the fixed-dose weekly combination of cagrilintide with semaglutide 2.4 mg produced a meaningful step up over semaglutide alone, while the dedicated REDEFINE 4 head-to-head came in below tirzepatide 15 mg and missed its non-inferiority endpoint. It also remains investigational and under regulatory review rather than prescribable in most markets, so the live comparison for most people is between an approved medicine and one that may or may not become an option.
CagriSema is a once-weekly fixed-dose combination of cagrilintide with semaglutide 2.4 mg that outperformed semaglutide alone inside REDEFINE 1 but failed to demonstrate non-inferiority to tirzepatide 15 mg in REDEFINE 4, and it is not approved.
The percentages that circulate side by side mostly come from trials that never met. Two comparisons in this field were randomised: CagriSema against semaglutide 2.4 mg and against cagrilintide alone inside REDEFINE 1, and CagriSema against tirzepatide in REDEFINE 4. Everything else lines up populations recruited years apart under different escalation rules, different trial lengths, and different estimands, any one of which can move a result by several percentage points on its own.
Only REDEFINE 1 and REDEFINE 4 randomised these medicines against one another, and every other comparison in circulation is cross-trial inference that functions as a hypothesis rather than a finding.
REDEFINE 1 is the source of the combination's headline number, and it randomised adults with obesity, or overweight plus a weight-related complication and without type 2 diabetes, across four arms under one protocol for 68 weeks. The step up over semaglutide alone is real, though dosing was flexible and only around half to two thirds of participants were on the maximum dose at the end, so the average carries many people who never received the full intended exposure.
| REDEFINE 1 arm, 68 weeks | Mean weight change, trial product estimand |
|---|---|
| Cagrilintide plus semaglutide 2.4 mg | Roughly 22.7 percent |
| Semaglutide 2.4 mg | Roughly 16.1 percent |
| Cagrilintide 2.4 mg | Roughly 11.8 percent |
| Placebo | Roughly 2.3 percent |
On the trial product estimand REDEFINE 1 reported roughly 22.7 percent mean weight loss for the combination against roughly 16.1 percent for semaglutide 2.4 mg, with the treatment policy estimand placing the combination at roughly 20.4 percent against roughly 3.0 percent for placebo.
REDEFINE 4 was built to settle the question that cross-trial arithmetic could not, and the answer landed in the opposite direction from what that arithmetic predicted. The two drugs performed far more similarly when they met inside one protocol than separate REDEFINE and SURMOUNT results suggested, with the gap running a few percentage points in tirzepatide's favour. A difference in a group mean also does not transfer cleanly to an individual, since response to any of these agents varies widely between people.
REDEFINE 4 randomised 809 adults over 84 weeks and reported 23.0 percent mean weight loss with CagriSema against 25.5 percent with tirzepatide 15 mg when full adherence is modelled, missing its primary non-inferiority endpoint.
Nothing in this class is gentle, and tolerability is where a comparison of average weight loss stops being the deciding factor. The reported difference between these agents is smaller than the difference between individuals, and the loss of lean mass that accompanies any large weight reduction applies across all of them, with the suggestion that amylin agonism spares lean tissue better resting on preclinical and early clinical work only.
Discontinuation for adverse events ran in the low to mid single digits by percentage in REDEFINE 1, broadly comparable to the semaglutide and tirzepatide pivotal trials, even though the combination produced more gastrointestinal events than semaglutide alone.
Amylin is co-secreted with insulin after a meal and signals that eating should stop, slowing gastric emptying, suppressing inappropriate glucagon release, and acting on the area postrema in the hindbrain. Cagrilintide is an engineered long-acting analogue of that hormone, so pairing it with semaglutide recruits a satiety circuit that does not overlap with the GLP-1 route rather than pushing harder on the same one.
| Feature | Cagrilintide plus semaglutide | Semaglutide alone | Tirzepatide |
|---|---|---|---|
| Receptors engaged | Amylin and calcitonin receptor complexes plus GLP-1 | GLP-1 | GLP-1 plus GIP |
| Principal satiety site | Hindbrain area postrema plus hypothalamic arcuate | Hypothalamic arcuate and brainstem | Two incretin receptors in one molecule |
| Strength of the mechanistic case | Both monotherapy arms active in REDEFINE 1; addition incomplete | Established in human trials | GIP contribution genuinely contested |
| Set point claim | Preclinical leptin sensitivity signal only | Not claimed | Not claimed |
Cagrilintide alone produced roughly 11.8 percent mean weight loss in REDEFINE 1, which establishes amylin agonism as an independently active weight mechanism even though the combined result fell short of simple arithmetic addition.
This is the dimension on which the newest agent is currently the weakest, and it is routinely lost in coverage built around weight percentages. The tempting shortcut is to assume that more weight loss delivers proportionally more outcome benefit, or that a benefit shown for one GLP-1 molecule extends to the class; neither assumption has held reliably in cardiovascular medicine. Intermediate markers move favourably across all of these agents, but intermediate markers are what outcome trials exist to test rather than replace.
CagriSema has no completed cardiovascular or organ outcome trial and its cardiovascular programme is still running, while semaglutide's cardiovascular outcomes trial reported roughly a 20 percent reduction in major adverse cardiovascular events.
Availability, not efficacy, is usually the binding constraint. Semaglutide 2.4 mg and tirzepatide are approved for chronic weight management across the United States, the European Union, and many other markets, while the combination is investigational and cannot be prescribed for weight management outside a trial until a decision is granted. Coverage is the variable that decides real cost, and it is inconsistent enough that an approved indication for a comorbidity often matters more to access than any weight loss percentage.
United States list prices for the approved weekly injectables have sat in the region of one thousand to fourteen hundred dollars per month, with manufacturer direct-to-patient cash programmes bringing self-pay pricing for certain doses down to roughly one hundred fifty to four hundred dollars.
Weight comes off fastest early, then the body's counter-regulatory responses push back through reduced resting energy expenditure and stronger hunger signalling. What separates these agents from their predecessors is that the curve keeps declining well past the point where older medicines flattened, and in the pivotal trials the strongest agents had still not clearly plateaued at 68 to 72 weeks.
Participants regained roughly two thirds of the lost weight in the year after semaglutide was withdrawn, with a similar pattern after tirzepatide withdrawal, and no withdrawal data specific to the combination has been published.
Set against the previous generation, the gap is not incremental; results in the 15 to 25 percent range push pharmacotherapy into territory previously reachable only through surgery. The older agents nonetheless keep advantages that get lost in the excitement, since several are oral, several cost a fraction of the weekly injectables, and several suit a patient whose other conditions make the newer agents a poor fit.
The older agents top out at roughly 3 to 10 percent mean weight loss against 15 to 25 percent for the weekly injectables, while sleeve gastrectomy and Roux-en-Y gastric bypass typically produce roughly 25 to 30 percent with durable outcome and mortality evidence behind them.
The pipeline is crowded enough that any ranking made today has a short shelf life, and every comparison across these agents is cross-trial and therefore soft. Phase 2 trials are small, enriched, shorter, and analysed in ways that systematically flatter results, and this field has already watched a headline number shrink between phase 2 and phase 3 more than once.
Retatrutide's roughly 24 percent mean weight loss over 48 weeks is phase 2 evidence only, a stage that has repeatedly produced figures larger than the phase 3 programmes that followed.
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