Also known as Maridebart cafraglutide · AMG 133
Amgen’s once-monthly antibody–peptide conjugate — a GIP-receptor-blocking antibody carrying two GLP-1 agonist peptides. Phase 2 reported up to ~20% weight loss at 52 weeks; Phase 3 MARITIME is running.
Research refreshed
MariTide (maridebart cafraglutide) is an investigational bispecific molecule that does something no other incretin drug does: it blocks the GIP receptor while activating the GLP-1 receptor. Structurally it is a monoclonal antibody against the GIP receptor with two GLP-1 analog peptides chemically attached, and the antibody scaffold gives it a half-life long enough for monthly — possibly less frequent — dosing. The Phase 2 trial (NEJM 2025) reported up to ~20% mean weight reduction at 52 weeks without a plateau. Amgen’s Phase 3 MARITIME program is ongoing; it is not approved.
MariTide sits at the center of an unresolved question in incretin biology. Tirzepatide activates the GIP receptor and produces more weight loss than GLP-1 alone; MariTide blocks the same receptor and also produces large weight loss. Human genetics motivated Amgen’s choice — variants that reduce GIP-receptor function are associated with lower body-mass index — and one proposed reconciliation is that sustained agonism desensitizes the receptor, so both approaches end up reducing GIP signaling. The question is not settled.
It is an antibody–peptide conjugate: a fully human monoclonal antibody that binds and blocks the GIP receptor, with two GLP-1 analog peptides joined to it through linkers. At roughly 150 kDa it is produced in mammalian cell culture and then conjugated — manufacturing closer to an antibody–drug conjugate than to a synthetic peptide.
In the Phase 2 trial (Jastreboff et al., NEJM 2025), adults with obesity and without diabetes lost up to about 20% of body weight at 52 weeks on monthly dosing, with weight still falling at the end of treatment; those with type 2 diabetes lost up to about 17%. Early dose escalation was marked by frequent nausea and vomiting, which the Phase 3 program addresses with slower titration. The Phase 3 MARITIME trials are enrolling across obesity, type 2 diabetes and related conditions, with first data expected in 2027; no regulatory filing has been made.
Antagonism of the GIP receptor by the antibody domain combined with GLP-1 receptor agonism by two conjugated peptide arms. The antibody’s FcRn recycling extends exposure to weeks.
Behind every vial of MariTide is the same exacting pipeline every research peptide runs — but the chemistry plays out differently for this molecule. Here is how MariTide, specifically, is brought into being.
On paper, MariTide weighs in at roughly 150,000 daltons. Before a single bond is made, the target sequence, salt form, and purity threshold are written down as the contract the finished material must meet.
MariTide is assembled by solid-phase peptide synthesis — the chain grows one protected residue at a time on resin, and what you fail to build cleanly here you pay to remove later.
The crude mixture — MariTide plus its deletions and side products — is then separated on preparative HPLC, and where the cut is taken decides the difference between a genuinely pure peptide and a barely-passable one.
A real batch of MariTide proves itself: identity confirmed by mass spectrometry against its ~150,000 Da, purity read directly off an analytical HPLC trace, water and counterion content measured. That batch-specific certificate of analysis is the only honest way to know what is actually in a vial of MariTide — and a short, cold, accountable chain of custody is how that purity survives the trip to your bench.
Producing MariTide to a genuine purity spec means solid-phase synthesis, preparative HPLC purification, and batch quality control — none of it cheap, and none of it something you can verify by eye.
Don't judge a vial by its cake. A fluffy, good-looking lyophilized powder reflects bulking agents and freeze-drying parameters — not purity. Insist on a batch-specific certificate of analysis.
Recent clinical trials and publications mentioning MariTide, pulled automatically from ClinicalTrials.gov and PubMed and refreshed daily. Listings are unfiltered search results, not curated endorsements.
MariTide (maridebart cafraglutide, AMG 133) is Amgen’s investigational once-monthly obesity drug — an antibody that blocks the GIP receptor, linked to two peptides that activate the GLP-1 receptor.
Partly. It is an antibody–peptide conjugate: a ~150 kDa monoclonal antibody with two GLP-1 analog peptides attached. It cannot be made by peptide synthesis alone.
This is genuinely unresolved. Tirzepatide activates the GIP receptor; MariTide blocks it; both reduce weight. One hypothesis is that chronic agonism desensitizes the receptor so that both strategies lower GIP signaling over time. Human genetic data linking reduced GIP-receptor function to lower BMI motivated the antagonist approach.
The Phase 2 trial (NEJM 2025) reported up to about 20% mean weight reduction at 52 weeks in adults with obesity without diabetes, and about 17% in those with type 2 diabetes. Phase 3 results are not yet available. Population means, not individual predictions.
No. It is investigational, in the Phase 3 MARITIME program, and no regulatory filing has been made. This page is a research reference, not medical advice.
The once-weekly GLP-1 receptor agonist behind Ozempic, Wegovy, and Rybelsus — FDA-approved for type 2 diabetes, chronic weight management, cardiovascular risk reduction, and MASH.
ViewThe once-daily GLP-1 agonist that preceded semaglutide — FDA-approved for diabetes (Victoza) and obesity (Saxenda).
ViewDual GIP / GLP-1 receptor agonist with industry-leading weight-loss endpoints.
ViewDosing protocols, mechanism, comparisons, and the latest trials — citation-backed answers grounded in PubMed, PubChem, and ClinicalTrials.gov.