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MARKET WATCHSeptember 12, 2026 · 7 min read

CagriSema vs retatrutide: the incretin arms race, scored on data

Novo Nordisk filed first. Eli Lilly's molecule is stronger. A head-to-head read of REDEFINE 1, REDEFINE 4 and TRIUMPH-4 — without the marketing.

Two bets on the same problem

Both companies are asking how much weight loss a weekly injection can produce before it stops being a drug and starts competing with surgery. Novo's answer is a combination: CagriSema pairs cagrilintide, a long-acting amylin analogue, with semaglutide 2.4 mg in a single injection. Amylin and GLP-1 suppress appetite through partly separate pathways, so the combination is additive rather than redundant. Lilly's answer is a single engineered peptide: retatrutide, activating GLP-1, GIP and glucagon receptors at once.

REDEFINE 1, read honestly

The REDEFINE 1 phase 3 trial (3,417 participants, 68 weeks, published in NEJM in 2025) is easy to misquote. On the treatment-policy estimand — the conservative analysis that counts everyone as randomized — CagriSema produced 20.4% mean weight loss versus 3.0% for placebo. The widely quoted 22.7% figure is the adherence-based estimand. Both are legitimate; only the first is comparable to how other drugs' pivotal results are usually reported. Context: semaglutide alone reached 14.9% on the same conservative basis, and 40.4% of CagriSema participants lost 25% or more of their body weight.

The head-to-head that settled the short-term question

REDEFINE 4 put CagriSema directly against tirzepatide for 84 weeks. Result: 23.0% versus 25.5% in adherent participants — CagriSema failed to show non-inferiority. That matters beyond pride: it calibrates the amylin-plus-GLP-1 ceiling. Meanwhile retatrutide's TRIUMPH-4 readout (December 2025) landed at 28.7% at 68 weeks, the largest phase 3 result ever reported for a non-surgical obesity intervention.

The scoreboard that actually matters

On conservative estimands: semaglutide 14.9%, CagriSema 20.4%, retatrutide higher again on its phase 3 readouts. Tirzepatide sits between the last two and beat CagriSema head-to-head. Novo's real advantage is temporal: CagriSema was filed with the FDA in December 2025 and will likely reach patients first. Lilly's advantage is pharmacological: a single molecule with a higher demonstrated ceiling. The commercial winner and the scientific winner may be different drugs.

What the gray market gets wrong

Cagrilintide vials sold online alongside semaglutide are not CagriSema. The trial product is a fixed-dose combination with a specific ratio, manufactured to pharmaceutical standard, titrated over months. Two separately purchased research peptides are a different — and unstudied — intervention. The codex treats cagrilintide as clinical-trials status with moderate human evidence precisely because its data exists almost entirely in combination, not alone.

The takeaway

  • 01CagriSema: 20.4% (conservative estimand) at 68 weeks in REDEFINE 1; filed with the FDA in December 2025.
  • 02In the REDEFINE 4 head-to-head, tirzepatide (25.5%) beat CagriSema (23.0%) at 84 weeks.
  • 03Retatrutide's TRIUMPH-4 readout of 28.7% is the largest phase 3 obesity result on record — approval pending.
  • 04Gray-market cagrilintide plus semaglutide is not the trial combination; ratio, titration and manufacturing all differ.

Verdict — WATCH

Both drugs work. The race is now about timing, cardiovascular outcomes and tolerability at target doses — not mechanism speculation.

References

  1. Novo Nordisk. REDEFINE 1 phase 3 results and NEJM 2025 publication (NCT05567796).
  2. Novo Nordisk. REDEFINE 4 head-to-head vs tirzepatide, 84-week results.
  3. Eli Lilly. TRIUMPH-4 phase 3 topline results, December 2025.
  4. Cagrilintide, semaglutide, retatrutide and tirzepatide monographs — Peptidify codex.