MariTide Monthly Injection: Phase 2 Data and MARITIME Phase 3 Status
MariTide (maridebart cafraglutide) is Amgen's once-monthly obesity injection, and as of October 2026 it is still investigational: not approved by the FDA or any other regulator. Its Phase 2 trial produced up to about 20% average weight loss at 52 weeks in people without diabetes, and the two 72-week Phase 3 trials that will decide its fate have estimated primary completion dates in January 2027.
Key takeaways
- Phase 2 (592 adults) showed 16.3% to 19.9% mean weight loss at 52 weeks without type 2 diabetes, versus 2.6% on placebo, when measured in people who stayed on treatment.
- The big weakness was vomiting at the start. Amgen redesigned Phase 3 to begin at 21 mg and step up over eight weeks.
- MARITIME-1 enrolled 3,853 people and MARITIME-2 enrolled 1,105; both have estimated primary completion in January 2027.
- The program now includes heart, heart-failure, sleep apnea, switch and extension trials, plus a stated goal of dosing as rarely as 4 to 6 times a year.
- You cannot get MariTide outside a clinical trial. Anything sold online under that name is not the Amgen product.
What MariTide is, and why it is different
Most GLP-1 drugs on the market are peptides injected weekly (Wegovy, Zepbound) or taken daily as pills. MariTide is built differently. It pairs GLP-1 receptor activation with blocking of the GIP receptor, the opposite of tirzepatide, which activates both. Fierce Biotech describes it as a monthly GLP-1 agonist and GIPR antagonist.
The design uses an antibody backbone, which is what lets it last long enough for monthly dosing. In its Q2 2026 earnings release, Amgen said its aim is for people to stay on MariTide "with as few as 4 or 6 doses per year" after a monthly start (Amgen Q2 2026 release, SEC filing). That is a goal, not a proven result.
The Phase 2 results, read carefully
The Phase 2 study (NCT05669599) enrolled 592 adults and was published in The New England Journal of Medicine alongside the June 2025 ADA presentation (Amgen press release). It ran two groups: 465 people with obesity or overweight but no diabetes, and 127 people who also had type 2 diabetes.
Amgen reported each result two ways. The efficacy estimand asks what happens if everyone stays on the drug. The treatment policy estimand counts everyone who was randomized, including people who stopped. The second number is closer to what a typical patient population might see.
| Group (52 weeks) | Efficacy estimand | Treatment policy estimand | Placebo |
|---|---|---|---|
| No type 2 diabetes (n=465) | 16.3% to 19.9% loss | 12.3% to 16.2% loss | 2.6% / 2.5% |
| With type 2 diabetes (n=127) | 12.1% to 17.0% loss | 8.4% to 12.3% loss | 1.4% / 1.7% |
Source: Amgen, June 2025. Ranges span the different dose arms.
In the diabetes group, HbA1c fell by up to 2.2 percentage points (efficacy estimand), per the same release. Fierce Biotech also noted that weight loss had not plateaued by week 52, which matters because the Phase 3 trials run 72 weeks.
The vomiting problem
The tolerability data are where the Phase 2 story got complicated. The trial tested arms that started straight at a full dose, and arms that stepped up from 70 mg. According to Fierce Biotech:
- Discontinuation due to gastrointestinal side effects ranged from 12% to 27% in obesity arms with no dose escalation.
- In dose-escalation arms, GI-related discontinuation was up to 7.8%.
- Vomiting was reported in as many as 92% of people in one arm (420 mg every eight weeks) and 43% in the gentlest four-week escalation arm.
Amgen said GI events were mostly limited to the first doses. A separate Phase 1 study testing lower starting doses reported vomiting in 24.4% and 22.5% of participants on two schedules, with no GI-related discontinuations (Amgen). That smaller study is what shaped the Phase 3 dosing.
How Phase 3 changed the dosing
For the MARITIME weight trials, Amgen moved to a three-step start: 21 mg, then 35 mg, then 70 mg over eight weeks, before people move to one of three target doses (Amgen). The ClinicalTrials.gov record for MARITIME-1 lists only "low," "medium" and "high" dose arms and does not publish the milligram amounts (ClinicalTrials.gov NCT06858839).
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The MARITIME Phase 3 program, trial by trial
Amgen's Q2 2026 release lists nine named MARITIME studies that are ongoing or enrolling (SEC filing). Here is what the public registries show for the main ones.
| Trial | Who it studies | Size | Key dates |
|---|---|---|---|
| MARITIME-1 | Obesity/overweight, no diabetes; primary endpoint is % weight change at week 72 | 3,853 (actual) | Started Mar 12, 2025; primary completion est. Jan 21, 2027 |
| MARITIME-2 | Obesity/overweight with type 2 diabetes | 1,105 | Started Mar 17, 2025; primary completion est. Jan 21, 2027 |
| MARITIME-CV | Established atherosclerotic heart disease plus overweight/obesity | 12,800 | Started Jul 25, 2025; primary completion est. Jun 30, 2028 |
| MARITIME-1 EXTENSION | People who finished MARITIME-1; long-term maintenance | 3,200 | Started Jul 23, 2026; primary completion est. Dec 26, 2027 |
| MARITIME-SWITCH (NCT07575399) | People who lost at least 10% on a weekly GLP-1 and switch to MariTide | Not listed in the Mount Sinai listing | Study dates May 11, 2026 to Feb 28, 2028 |
Sources: ClinicalTrials.gov (MARITIME-1); registry mirrors for MARITIME-2, MARITIME-CV and MARITIME-1 EXTENSION; Mount Sinai (MARITIME-SWITCH). "Est." dates are sponsor estimates and often move.
The rest of the program, per Amgen's Q2 2026 release, includes MARITIME-HF (heart failure events and cardiovascular risk), MARITIME-OSA-1 and OSA-2 (sleep apnea, with and without PAP therapy) and a MARITIME-2 extension. Amgen also said three Phase 3 studies in type 2 diabetes would start in 2026, and a Phase 2b study on liver fat is enrolling. ClinicalTrials.gov already lists one of them, a not-yet-recruiting Phase 3 titled "Maridebart Cafraglutide Versus Semaglutide in Participants With Type 2 Diabetes".
The SWITCH trial is the one to watch if you're already on a GLP-1
MARITIME-SWITCH asks a practical question: can someone who has already lost weight on a weekly shot move to a monthly one and hold it? The listing on Mount Sinai's trial site requires at least 10% weight loss on a weekly GLP-1, stable weight and dose, BMI of 25 or higher, and no diabetes. Amgen's release says participants will be switching from weekly tirzepatide or weekly semaglutide to MariTide on an every-eight-week or quarterly schedule.
What about the maintenance and quarterly dosing data?
Part 2 of the Phase 2 study is the source of the "4 to 6 doses a year" idea. Only people who had lost at least 15% by week 52 were eligible. They were re-randomized to placebo, monthly doses of 70, 140 or 420 mg, or 420 mg every 12 weeks (Amgen).
At the J.P. Morgan Healthcare Conference in January 2026, Amgen said MariTide worked as maintenance on monthly and "less frequent dosing patterns," and that a separate 24-week Phase 2 in type 2 diabetes showed "clinically meaningful" drops in HbA1c and weight (Clinical Trials Arena). The coverage we reviewed did not include the actual maintenance percentages, and Amgen's Q2 2026 release gave no new efficacy numbers. Until full data are published, treat quarterly dosing as a hypothesis.
When could MariTide be approved?
No one can say yet. Here is what the record supports as of October 2026:
- The two core weight-loss trials have estimated primary completion dates in January 2027, and Fierce Biotech, citing ClinicalTrials.gov, reported that both are expected to read out in 2027.
- Amgen's Q2 2026 release gives no filing date.
- Any FDA application would follow those readouts, and FDA review takes time after that.
Be skeptical of websites quoting a specific approval month. We could not find one in Amgen's own disclosures.
How MariTide fits with what's available now
If the Phase 3 numbers land near the Phase 2 treatment policy results (roughly 12% to 16% at one year in people without diabetes), MariTide's selling point would be convenience and maintenance, not record-setting weight loss. If quarterly maintenance holds up, that could matter a lot for people who struggle with weekly injections or monthly refills.
The open questions are tolerability with the new start, whether weight loss keeps going to week 72, and what the heart outcomes trial shows. If you're interested in joining a MARITIME study, search the trial names on ClinicalTrials.gov and talk to your prescriber about whether you'd qualify.
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Frequently asked questions
Is MariTide FDA approved?
No. As of October 2026 MariTide (maridebart cafraglutide) is investigational and available only in clinical trials. Its two main Phase 3 weight-loss trials have estimated primary completion dates in January 2027.
How much weight did people lose on MariTide in Phase 2?
At 52 weeks, people without type 2 diabetes lost 16.3% to 19.9% on average if they stayed on treatment, or 12.3% to 16.2% counting everyone randomized, versus about 2.5% on placebo. People with type 2 diabetes lost somewhat less.
What were MariTide's main side effects?
Gastrointestinal effects, especially vomiting at the start of treatment. Arms that started at full dose had 12% to 27% discontinuation for GI effects, versus up to 7.8% in arms that stepped up the dose, which is why Phase 3 starts at 21 mg.
Can MariTide be dosed less than monthly?
Amgen says its goal is maintenance with as few as 4 or 6 doses a year, and Phase 2 Part 2 tested a dose every 12 weeks. Detailed maintenance numbers had not been released in the sources we reviewed, so quarterly dosing remains unproven.
What is the MARITIME-SWITCH trial?
It is a Phase 3 study of people who already lost at least 10% of their weight on weekly semaglutide or tirzepatide and then switch to MariTide, to see whether they keep the weight off.
Sources
- Amgen: Results from Phase 2 obesity study of monthly MariTide presented at ADA 85th Scientific Sessions (June 2025)
- Fierce Biotech: Amgen adjusts Phase 3 dosing plan for MariTide
- Amgen Q2 2026 earnings release (SEC Form 8-K)
- ClinicalTrials.gov: MARITIME-1 (NCT06858839)
- Registry record: MARITIME-2 (NCT06858878)
- Registry record: MARITIME-CV (NCT07037433)
- Registry record: MARITIME-1 EXTENSION (NCT07684235)
- Mount Sinai: MARITIME-SWITCH trial listing
- Clinical Trials Arena: JPM26, Amgen MariTide maintenance and T2D Phase II
- ClinicalTrials.gov: Maridebart Cafraglutide Versus Semaglutide in Type 2 Diabetes (NCT07866066)
- FDA: Concerns with unapproved GLP-1 drugs used for weight loss
Medical disclaimer: This article is general information, not medical advice, and does not replace a licensed clinician who knows your history. Approvals, labels, coverage and prices change; check the linked sources and talk with your prescriber or pharmacist before making decisions about any medication.