MariTide: Amgen's Once-Monthly GLP-1 That Could Change the Game

Quick answer: What is MariTide?

MariTide (maridebart cafraglutide) is Amgen's investigational GLP-1 medication that stands out for two reasons: it's a once-monthly injection (not weekly), and it uses a novel GIP receptor antagonist mechanism — the opposite approach from tirzepatide's GIP agonism. Phase 2 results published in NEJM 2025 showed up to ~20% weight loss, placing it in the same efficacy range as Zepbound.

MariTide is currently in Phase 3 trials (the MARITIME program), with primary completion estimated for January 2027. If successful, Amgen could file for FDA approval in 2028.

MariTide vs other GLP-1 medications

The GIP antagonist advantage: why it matters

The GLP-1 drug landscape has split into two mechanistic camps around GIP (glucose-dependent insulinotropic polypeptide):

• GIP agonists (tirzepatide, retatrutide): Activate the GIP receptor to enhance insulin secretion and potentially improve tolerability of GLP-1 side effects.
• GIP antagonists (MariTide): Block the GIP receptor, which may drive weight loss through increased energy expenditure and altered fat metabolism — a fundamentally different pathway.

Both approaches produce meaningful weight loss, but the antagonist route is unproven in Phase 3. If MariTide succeeds, it would offer patients a mechanistically distinct option — valuable for those who don't respond well to or can't tolerate GIP agonists.

MariTide clinical trial timeline

Why once-monthly dosing matters

For many patients, the weekly injection is a barrier — not because of pain, but because of the psychological burden of frequent self-injection. A once-monthly injection would reduce injection frequency by 75% compared to weekly GLP-1s. This could improve:

• Adherence: Fewer doses mean fewer missed doses
• Convenience: Monthly clinic visits or self-injection fit more easily into routines
• Travel: No need to pack and refrigerate weekly doses for trips
• Psychological comfort: Less frequent needle anxiety

However, a missed monthly dose has a bigger impact than a missed weekly dose. Patients would need to be disciplined about their monthly schedule.

MariTide in the competitive landscape

MariTide is one of several next-generation GLP-1 drugs in development. Here's where it stands:

• Retatrutide (Eli Lilly): Triple agonist, 28.3% weight loss in Phase 3, filing Q1 2027 — further along than MariTide
• CagriSema (Novo Nordisk): Amylin + semaglutide, ~22.7% weight loss, NDA under FDA review — closest to approval
• Survodutide (Boehringer/Zealand): GLP-1/glucagon dual, 16.6% in Phase 3 — similar timeline to MariTide
• MariTide (Amgen): GIP antagonist, ~20% in Phase 2, Phase 3 ongoing — unique mechanism but latest to market

The bottom line

MariTide is an exciting addition to the GLP-1 pipeline, offering a unique once-monthly dosing schedule and a novel GIP antagonist mechanism. However, it won't be available until 2028 at the earliest. If you're considering GLP-1 treatment now, don't wait — Wegovy, Zepbound, and Foundayo are all FDA-approved and available today. You can always discuss switching to MariTide with your healthcare provider if it becomes available.