CagriSema is two drugs given together once a week: semaglutide 2.4 mg, the molecule behind the figures in the semaglutide weight-loss article, and cagrilintide 2.4 mg, a long-acting analog of amylin, a hormone the pancreas releases alongside insulin. The premise is that two satiety pathways do more than one. The trials tested that premise and answered it, and the answer is more interesting than either the headline or the reaction to it.
REDEFINE 1, and what a coprimary endpoint means
REDEFINE 1 was a 68-week phase 3a trial in adults without diabetes who had a body-mass index of 30 or higher, or 27 or higher with at least one obesity-related complication. It randomized 3,417 participants: 2,108 to cagrilintide-semaglutide, 302 to semaglutide alone, 302 to cagrilintide alone and 705 to placebo.[1]
The coprimary endpoints were the relative change in body weight and the proportion reaching a 5% reduction, both against placebo. Mean body weight changed −20.4% with the combination against −3.0% with placebo, an estimated difference of −17.3 percentage points (95% CI, −18.1 to −16.6; P < 0.001). Reductions of 20%, 25% and 30% or more were all reached more often than on placebo (P < 0.001 for each). Gastrointestinal adverse events affected 79.6% of the combination group and 39.9% of the placebo group, mostly transient and mild to moderate.[1] Both endpoints were met. Nothing about the trial failed.
What the second ingredient is, and what it does alone
Amylin is co-secreted with insulin and slows gastric emptying and suppresses appetite through a pathway distinct from the incretin receptors. Cagrilintide is a long-acting analog of it, dosed weekly at 2.4 mg to match the semaglutide schedule. REDEFINE 1 is unusual in having run a monotherapy arm of that second ingredient, which is what makes the combination assessable rather than merely impressive.
The trial is also a reminder that a placebo arm in an obesity trial is not an untreated arm. Every group received lifestyle intervention, and the placebo group still lost 3.0% of body weight over 68 weeks — a figure worth holding in mind whenever a marketing page compares a program against doing nothing.[1]
The number that mattered was never the placebo comparison
A combination is judged against its parts, and the placebo arm says nothing about whether the second drug earned its place. Two published analyses answer that question directly.
REDEFINE 5 was a head-to-head. It randomized 331 adults in Japan and Taiwan, with or without type 2 diabetes, to the fixed-dose combination or to semaglutide 2.4 mg alone for 68 weeks. Mean body weight changed −18.4% with the combination against −11.9% with semaglutide alone, an estimated treatment difference of −6.5 percentage points (95% CI, −8.4 to −4.6; p < 0.0001). Adverse events were reported in 87% and 84% of the two groups, and gastrointestinal events in 53% and 51%.[3]
A post hoc analysis of REDEFINE 1 asked the same question through treatment targets rather than percentages. The proportion reaching both a body-mass index below 27 and a waist-to-height ratio below 0.53 at week 68 was 30.3% on the combination, 19.1% on semaglutide alone, 9.0% on cagrilintide alone and 3.3% on placebo.[6] Cagrilintide by itself did roughly half of what semaglutide by itself did, and adding it moved target attainment by about eleven percentage points.
Against a drug already on the market
REDEFINE 1's −20.4% at 68 weeks sits beside a published figure that was already available: in SURMOUNT-1, a 72-week trial that randomized 2,539 adults with obesity and without diabetes, tirzepatide 15 mg produced a mean change of −20.9% (95% CI, −21.8 to −19.9), and 57% of that group lost 20% or more.[7]
Those are separate trials, four weeks apart in duration, with different populations, different estimands and no head-to-head between them, so the two means cannot be subtracted from one another. What they do establish is the context a reader is entitled to: a two-drug combination landed in the same region as a single agent that had been approved and on pharmacy shelves for years. The evidence on comparing across trials like this is set out in the tirzepatide and semaglutide article.
With diabetes, a smaller weight number and a large glycemic one
REDEFINE 2 randomized 1,206 adults with type 2 diabetes, a body-mass index of 27 or more and a glycated hemoglobin of 7% to 10%, in a 3:1 ratio against placebo for 68 weeks. Mean body weight changed −13.7% against −3.4%, an estimated difference of −10.4 percentage points (95% CI, −11.2 to −9.5; P < 0.001) — about seven points less than the same regimen produced in participants without diabetes.[2]
The glycemic result went the other way. A glycated hemoglobin of 6.5% or below was reached by 73.5% of the combination group and 15.9% of the placebo group.[2] Gastrointestinal events affected 72.5% against 34.4%. A regimen that looks unremarkable on the weight axis in this population is doing something substantial on the glucose axis, which is the two-indication problem described in the diabetes-versus-weight-loss article.
Significant, and 0.16 percentage points
The cleanest illustration of the gap between “met its endpoint” and “changed the picture” is REIMAGINE 2. It randomized 2,713 people with type 2 diabetes on metformin across 30 countries, and its primary endpoint was the change in glycated hemoglobin with the combination against semaglutide 2.4 mg alone at 68 weeks.
From a mean baseline of 8.2%, glycated hemoglobin fell 1.91 percentage points on the combination and 1.75 percentage points on semaglutide alone: an estimated treatment difference of −0.16 percentage points (95% CI, −0.27 to −0.05; p = 0.0035).[4] The result is statistically significant and the interval excludes zero. It is also a sixth of a percentage point of glycated hemoglobin, obtained by adding a second weekly drug, with adverse events reported in 86.9% of the combination group against 81.2% of the semaglutide group.
Blood pressure fell, except where it was hardest to move
A secondary and post hoc analysis of REDEFINE 1 examined blood pressure. Systolic pressure changed −10.9 mm Hg with the combination against −2.8 mm Hg with placebo, and diastolic −5.4 against −1.7 mm Hg. Blood pressure targets were reached by 63.0% against 32.0%, and among participants taking antihypertensive medication during the trial, 39.6% of the combination group reduced or stopped it against 18.8% on placebo.[5]
The subgroup that most needs a new option is the one where the analysis stops short. Among the 167 participants with resistant hypertension at baseline, 42.0% on the combination and 29.3% on placebo reached target, an odds ratio of 1.7 with a 95% CI of 0.7 to 4.4 — an interval that includes no effect.[5] The direction is encouraging and the subgroup is too small to have settled anything. Cardiovascular endpoints for the class more broadly are covered in the cardiovascular article.
It is not approved, and half of it cannot be compounded
No product containing cagrilintide appears in Drugs@FDA, alone or in combination. The FDA states that cagrilintide, like retatrutide, cannot be used in compounding under federal law, is not a component of an FDA-approved drug, and has not been found safe and effective for any condition.[8] Compounded preparations generally are not FDA-approved and are not reviewed by the agency for safety, efficacy or quality before a pharmacy dispenses them; this ingredient is barred from that route outright. What is and is not in a compounded preparation is the subject of the vial contents article.
So any offer of this combination today is an offer of something that is not the trial regimen. Anything promising the −20.4% figure is quoting a 68-week protocol run with a manufactured investigational product under supervision, which is the distinction between a trial result and a purchase.
What the published record does not yet contain
No cardiovascular outcome trial of this combination has been published, so the one class benefit that carried semaglutide beyond weight has not been demonstrated for it. There is no randomized head-to-head against tirzepatide. The only published head-to-head against semaglutide alone, REDEFINE 5, randomized 331 participants at 22 sites in one region, which is roughly a tenth the size of REDEFINE 1 and drawn from a different population.[3] And the blood-pressure subgroup that would matter most to a reader already taking three antihypertensives numbered 167 people.[5]
The tolerability picture, by contrast, is consistent and large: four out of five participants on the combination in REDEFINE 1 reported a gastrointestinal adverse event, against two out of five on placebo.[1] Most were transient and mild to moderate, and how long that usually runs in this class is covered in the nausea article. None of it predicts anything about a preparation bought outside the approved system, because no such preparation has been studied at all.