REDEFINE 4 completes: Novo Nordisk's CagriSema tested directly against tirzepatide

Novo Nordisk's REDEFINE 4 trial, which pitted its investigational obesity drug CagriSema directly against tirzepatide, reached its primary completion date on December 8, 2025, according to the trial's registry listing ^[1]. The 809-participant, 84-week open-label phase 3 study is registered on ClinicalTrials.gov as NCT06131437, titled "A Research Study to See How Well CagriSema Compared to Tirzepatide Helps People With Obesity Lose Weight" ^[1].

The design matters as much as the result. Most obesity drug trials compare a new medicine with a placebo, which tells you how much weight people lose versus nothing, but not how the drug stacks up against what is already on pharmacy shelves. REDEFINE 4 instead used an active comparator — a group of participants receiving a treatment already considered effective by clinicians ^[1]. In this case, that comparator is tirzepatide, the molecule sold in the US as Mounjaro for type 2 diabetes and Zepbound for obesity.

A primary completion date is a technical milestone, not a results announcement. It marks the point when the last participant was assessed for the trial's main outcome measure. It does not mean the data have been analyzed, presented at a medical meeting, published in a journal or submitted to regulators. As of now, no outcome numbers from REDEFINE 4 appear in the material available here, and the company has not released topline findings through these sources.

Several specifics are also not established by the available registry text: the exact doses tested in each arm, the precise definition of the primary endpoint, the countries and sites involved, and whether the trial was designed to show that CagriSema is better than tirzepatide or merely comparable. Those details determine how the eventual numbers should be read, so they are worth waiting for rather than assuming.

Why it matters for patients

Right now, people choosing between GLP-1–based obesity medicines and their doctors mostly compare trials that were run separately, in different patient populations, at different times, with different rules about diet and follow-up. Those cross-trial comparisons are notoriously unreliable. A registration-grade head-to-head study removes much of that guesswork because both groups are enrolled under the same protocol and measured the same way.

The trade-off here is that REDEFINE 4 is open-label ^[1], meaning participants and investigators knew which drug was being given. Open-label designs are common when two injectable regimens have different dosing schedules and devices, but they can influence how people report side effects and how long they stay in a trial. That is a limitation to keep in mind when results appear.

For US patients, the practical stakes are about future choice and, eventually, cost. If a second manufacturer can show its product performs at least as well as tirzepatide in a direct comparison, that strengthens its case with regulators and with the insurers and pharmacy benefit managers who decide which obesity drugs are covered and at what tier. If it cannot, formularies may stay concentrated around existing options. Neither outcome is knowable until the data are public. CagriSema is not approved by the FDA, and enrollment in a completed trial does not imply approval.

What happens next

Under US law, sponsors of applicable clinical trials generally must submit results information to ClinicalTrials.gov within one year of the primary completion date ^[1]. That would point to a posting deadline around December 2026 for REDEFINE 4. However, a sponsor applying for FDA approval of a new drug or a new use can file a certification to delay results submission for up to two years from the date that certification is first submitted, unless certain events happen sooner ^[1]. Companies often present headline findings at a scientific conference well before the registry entry is filled in, so the first public numbers could come earlier — but no presentation date has been announced in these sources.

Until then, the size of any difference between CagriSema and tirzepatide on weight loss, tolerability and discontinuation rates is simply not yet known.