On 23 August 2026, Phase 3a results from the REDEFINE 1 trial confirmed that a once-weekly combination of cagrilintide and semaglutide produced mean body-weight reductions exceeding 20 percent in adults with overweight or obesity, with 60 percent of adherent participants crossing that threshold and 23 percent losing 30 percent or more over 68 weeks, according to trial results reported by Applied Clinical Trials Online. The data, published in The New England Journal of Medicine under lead author W. Timothy Garvey, draw on 3,417 adults without type 2 diabetes and represent the largest controlled dataset yet assembled for a dual amylin–GLP-1 agonist combination. Novo Nordisk sponsored the trial, registered as NCT05567796.

The figures place the investigational product CagriSema in a weight-loss range previously associated with bariatric surgery rather than pharmacotherapy, and they arrive at a moment when clinicians and regulators on both sides of the Atlantic are weighing whether single-pathway GLP-1 agonists can be improved upon without adding procedural risk. The combination carries no marketing authorization in the United States or the European Union, and no target action date appears in public FDA or EMA dockets as of this reporting.

Efficacy Across Estimands and Thresholds

Participants were randomized in a 21:3:3:7 ratio to CagriSema (cagrilintide 2.4 mg plus semaglutide 2.4 mg, n = 2,108), semaglutide 2.4 mg alone (n = 302), cagrilintide 2.4 mg alone (n = 302), or placebo (n = 705), with lifestyle interventions applied across all four arms. Coprimary endpoints were relative change in body weight and the proportion achieving at least 5 percent loss at week 68, both assessed against placebo. Confirmatory secondary endpoints tracked the 20, 25, and 30 percent thresholds.

Under the treatment-policy estimand, which counts every randomized participant regardless of adherence, CagriSema produced a mean body-weight reduction of 20.4 percent at week 68, compared with 3.0 percent for placebo, an estimated difference of −17.3 percentage points (95% CI, −18.1 to −16.6; P < .001), as summarized in the American College of Cardiology's journal scan of the REDEFINE publications. When the analysis shifted to the trial-product estimand, modelling only participants who remained on assigned therapy, the mean loss climbed to 22.7 percent. Semaglutide alone yielded roughly 14.9 percent mean loss; cagrilintide alone, 11.8 percent. Under the treatment-policy analysis, 34.7 percent of CagriSema recipients achieved at least 25 percent loss, and 19.3 percent reached 30 percent, compared with 0.4 percent on placebo at the highest bar. For reference, semaglutide monotherapy in the STEP 1 program produced approximately 14.9 percent mean loss, placing CagriSema's incremental gain at roughly eight percentage points of additional mean reduction.

No weight-loss plateau was observed through week 68, though the trial was not designed to assess durability beyond that window. Investigators also recorded improvements in waist circumference, blood pressure, lipid profiles, and glycemic markers, classified as secondary cardiometabolic endpoints. From a transatlantic regulatory standpoint, these secondary signals will matter: the EMA has historically required robust cardiometabolic context before granting obesity indications, while the FDA has leaned more heavily on the primary weight endpoint. Neither agency has yet opened a public review for CagriSema.

Mechanism and the Lean-Mass Question

Cagrilintide is a long-acting amylin analog acting on receptors in the hypothalamus, hindbrain, and septum, regions governing both homeostatic and hedonic appetite, while semaglutide stimulates GLP-1 receptors along partially overlapping but distinct neural circuits, as described in Endocrinology Advisor's coverage of the combination's pharmacology. The trial investigators attributed the additive weight effect to this complementary receptor engagement, though the NEJM paper does not prove that the mechanism, rather than simple dose exposure, explains the superiority over either monotherapy. The distinction matters: mechanism plausibility is not clinical proof, and regulators in both jurisdictions will evaluate the efficacy data on its own terms.

Body composition was listed among secondary endpoints, and investigators flagged it for further analysis, but the published dataset does not yet resolve how much of the total weight reduction came from fat mass versus lean tissue. For clinicians tracking sarcopenia risk in older adults or patients with low baseline muscle mass, that unresolved ratio is a variable the primary endpoint cannot answer. This concern sits within a broader debate across weight loss peptides research, where the proportion of lean tissue lost has become a scrutiny point in both FDA and EMA review pathways. Safety signals in REDEFINE 1 were reported as consistent with the established GLP-1 receptor agonist class: gastrointestinal events during dose titration were the most frequently recorded adverse events, and no new safety signals emerged relative to semaglutide alone. The 68-week observation period cannot exclude rarer or slower-onset risks, and no adjudicated cardiovascular-outcome data accompanied this publication.

Regulatory Distance and Unresolved Questions

CagriSema is not approved in any jurisdiction. Cagrilintide itself has never received marketing authorization as a standalone agent, and the combination product remains classified as investigational. Novo Nordisk completed REDEFINE 2, a parallel Phase 3a study in 1,200 adults with type 2 diabetes, showing a 15.7 percent mean weight loss under adherence-adjusted analysis, but that population-specific dataset does not substitute for a regulatory filing. The company has indicated it is pursuing approvals, yet the timeline for submissions in North America and Europe has not been disclosed publicly.

Investigators, including Garvey, have called for further analyses linking individual dose-response curves to the degree of weight loss achieved, a question the fixed-dose design of REDEFINE 1 was not built to answer. Dosing was adjusted on the basis of individual needs and clinical judgment, and the relationship between adherence-adjusted and intention-to-treat outcomes will require additional scrutiny before prescribers can extrapolate these results to routine practice. For the broader field of peptide therapy, the REDEFINE 1 data establish that dual-pathway agonism can outperform single-agent GLP-1 therapy in a controlled setting of 3,417 participants; whether that advantage survives regulatory review, real-world adherence patterns, and longer safety follow-up remains the open question Novo Nordisk now carries into its next filing.