MariTide: What to Know About the Monthly Weight-Loss Injection
MariTide (maridebart cafraglutide) is Amgen's investigational obesity drug, designed to start with monthly injections and possibly need as few as 4 or 6 doses a year for maintenance. It is in Phase 3 trials, not FDA approved, and the pivotal MARITIME-1 data point is estimated for 2027-01-21.
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MariTide is an investigational weight-loss drug from Amgen. Its generic name is maridebart cafraglutide, and it also carries the code name AMG 133 [1, 2]. It is given as a subcutaneous injection, and Amgen says its long-acting design supports starting with monthly dosing and staying on the drug with as few as 4 or 6 doses per year [1]. It is not FDA approved, and several of its Phase 3 trials are still recruiting volunteers [1, 2, 4, 5, 6, 7].
The main weight-loss trial, MARITIME-1, finished enrolling with 3,853 participants and is estimated to complete its primary data collection on 2027-01-21 (January 21, 2027) [2]. That is the earliest date a pivotal result could arrive, though registry dates are estimates that can move [2].
How does MariTide work in the body?
MariTide is what Amgen calls an antibody-peptide conjugate. It does two things at once: it activates the GLP-1 receptor and it antagonizes (blocks) the GIP receptor, called GIPR [1]. That combination is what separates it from the medicines people currently take for weight loss, which Amgen describes as weekly GLP-1 receptor agonists — weekly tirzepatide and weekly semaglutide [1, 4].
It is an investigational agent in Phase 3 testing [1, 2]. Amgen’s second quarter 2026 report lists a large MariTide program: weight-loss trials in people with and without type 2 diabetes, heart and sleep apnea outcome trials, a switch trial, and long-term extension studies [1]. The same report states that future development of AMG 513, another Amgen obesity program, will be discontinued [1].
How often is MariTide injected?
Amgen says MariTide’s long-acting design supports monthly dosing at the start of treatment, and maintenance with as few as 4 or 6 doses per year [1]. The trials test several schedules: monthly, every eight weeks, and quarterly [1].
In MARITIME-SWITCH, people move from a weekly GLP-1 receptor agonist (weekly tirzepatide or weekly semaglutide) to MariTide on an every-eight-week or quarterly schedule [1, 4]. The extension studies test whether weight loss holds on less frequent dosing: MARITIME-1 EXTENSION uses monthly, every-eight-week, or quarterly dosing, and MARITIME-2 EXTENSION uses monthly and every-eight-week dosing [1].
The exact dose sizes and intervals are not public. In MARITIME-1, the arms are labeled only as high, medium, and low dose [2]. In MARITIME-SWITCH, the two arms are labeled dosing schedule 1 and dosing schedule 2 [4].
What is MARITIME-1, the pivotal weight-loss trial?
MARITIME-1 (registry ID NCT06858839) is a Phase 3, randomized, double-blind, placebo-controlled study in adults with obesity or overweight who do not have type 2 diabetes [2]. It enrolled 3,853 participants (an actual count), started on 2025-03-12 (March 12, 2025), and is listed as active but no longer recruiting [2].
Participants are assigned to one of three MariTide dose arms — high, medium, or low — or to placebo, all given subcutaneously for 72 weeks [2]. The primary outcome is the percent change in body weight at week 72 [2]. Secondary outcomes include the share of participants reaching at least 5%, 10%, 15%, or 20% weight loss, plus changes in waist circumference, systolic blood pressure, and fasting triglycerides [2].
The registry lists an estimated primary completion date of 2027-01-21 (January 21, 2027), and an estimated study completion date of 2027-04-16 (April 16, 2027) [2].
What is MARITIME-SWITCH for people already on a weekly GLP-1?
MARITIME-SWITCH (NCT07575399) is a Phase 3 trial for adults who have already lost weight on a weekly GLP-1 receptor agonist and would move to MariTide on an every-eight-week or quarterly schedule [1, 4]. It is recruiting, with an estimated enrollment of 300 participants; it started on 2026-05-11 (May 11, 2026), and its estimated primary completion date is 2028-01-03 (January 3, 2028) [4].
To enter, a person needs a BMI of at least 25, weight loss of at least 10% on a weekly GLP-1 receptor agonist, a stable body weight, a stable dose, and stable gastrointestinal tolerability on that drug [4]. People with type 1 or type 2 diabetes are excluded [4].
The trial has two MariTide arms — dosing schedule 1 and dosing schedule 2 — and no placebo arm is listed [4]. Its primary outcome is percent change in body weight at week 68; a key secondary outcome is the share of participants keeping at least 80% of the weight they lost on their prior weekly drug [4].
What are the heart and sleep apnea trials testing?
Two large trials look at whether MariTide reduces serious outcomes, not just weight:
- MARITIME-CV (NCT07037433) enrolls adults with established atherosclerotic cardiovascular disease plus overweight or obesity. It has an estimated enrollment of 12,800, started on 2025-07-25 (July 25, 2025), and is recruiting. Its estimated primary completion date is 2028-06-30 (June 30, 2028), with estimated study completion on 2030-09-29 (September 29, 2030). The goal is to show MariTide is superior to placebo, on top of standard care, at reducing cardiovascular illness and death [1, 5].
- MARITIME-HF (NCT07037459) enrolls adults with heart failure with preserved or mildly reduced ejection fraction plus obesity. It has an estimated enrollment of 5,056, is recruiting, and shares the same estimated dates: primary completion 2028-06-30 (June 30, 2028), and study completion 2030-09-29 (September 29, 2030). It measures heart failure hospitalizations, urgent heart failure visits, cardiovascular deaths, and symptoms, and it runs as a double-blind period followed by an open-label extension [1, 6].
Two sleep apnea trials are also running. MARITIME-OSA-1 (NCT07225686) enrolls an estimated 250 adults with obstructive sleep apnea who use positive airway pressure (PAP) therapy. It runs 52 weeks, and its primary outcome is the change in apnea-hypopnea index (AHI) at week 52, with estimated primary completion on 2027-09-29 (September 29, 2027) [1, 7]. MARITIME-OSA-2 enrolls adults with sleep apnea who are not on PAP therapy [1].
What is the full MariTide trial lineup?
Beyond MARITIME-1, Amgen lists MARITIME-2, a Phase 3 chronic weight management study in adults with obesity or overweight who have type 2 diabetes, now ongoing [1]. Three more Phase 3 studies in people with type 2 diabetes are planned to start in 2026, and a Phase 2b study is enrolling adults with obesity or overweight and elevated liver fat to measure liver fat reduction and weight loss [1].
Here is how the trials with public registry records compare:
| Trial | Registry ID | Who it enrolls | Enrollment | Status | Estimated primary completion |
|---|---|---|---|---|---|
| MARITIME-1 [2] | NCT06858839 | Obesity or overweight, no type 2 diabetes | 3,853 (actual) | Active, not recruiting | 2027-01-21 |
| MARITIME-SWITCH [4] | NCT07575399 | Switching from a weekly GLP-1 RA | 300 (estimated) | Recruiting | 2028-01-03 |
| MARITIME-CV [5] | NCT07037433 | Established cardiovascular disease plus overweight or obesity | 12,800 (estimated) | Recruiting | 2028-06-30 |
| MARITIME-HF [6] | NCT07037459 | Heart failure plus obesity | 5,056 (estimated) | Recruiting | 2028-06-30 |
| MARITIME-OSA-1 [7] | NCT07225686 | Sleep apnea on PAP therapy | 250 (estimated) | Recruiting | 2027-09-29 |
The extension studies enroll only people who completed MARITIME-1 or MARITIME-2 [1].
When will Phase 3 results and an FDA decision arrive?
The earliest pivotal data point is MARITIME-1’s estimated primary completion date of 2027-01-21 (January 21, 2027) [2]. Registry dates are estimates and can shift as trials run [2]. The MARITIME-1 record currently shows “No Results Posted” [2].
MariTide is not FDA approved, and Amgen’s materials give no filing date or approval timeline [1, 2]. Amgen’s research and development spending rose 7% in the second quarter of 2026, driven primarily by MariTide’s later-stage programs, which signals continued investment but says nothing about timing [1].
What is known about MariTide side effects so far?
The side-effect profile is not yet established. The Phase 3 trials count treatment-emergent adverse events as outcomes — tracked through roughly 88 weeks in MARITIME-1 and up to 84 weeks in MARITIME-SWITCH — but the MARITIME-1 record shows no posted results [2, 4].
The exclusion criteria in MARITIME-1 mirror warnings familiar from the GLP-1 class: people with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2 are excluded, as are people with a history of pancreatitis, unstable major depressive disorder within two years, or a lifetime suicide attempt [2]. MARITIME-SWITCH additionally requires stable gastrointestinal tolerability on the prior weekly drug [4].
How can I find or join a MariTide trial?
MARITIME-1 is closed to new participants [2]. Recruiting right now: MARITIME-CV, MARITIME-HF, MARITIME-OSA-1, MARITIME-OSA-2, MARITIME-SWITCH, the two extension studies (for completers only), and the Phase 2b liver-fat study [1, 4, 5, 6, 7].
Eligibility varies by trial. MARITIME-1’s pattern gives a sense of the weight-loss program overall: age 18 or older, BMI of 30 or more, or a BMI of 27 to under 30 with a weight-related condition such as hypertension, dyslipidemia, sleep apnea, cardiovascular disease, or MASLD/MASH, plus at least one failed attempt at weight loss through diet and exercise [2]. MARITIME-OSA-1 requires an AHI of 15 or more, a BMI of 27 or more, and at least three months of continued PAP therapy [7].
Amgen’s trial site, amgentrials.com, offers keyword and location search with distance filters from 10 to 250 miles, and lists MARITIME-HF as recruiting for ages 18 to 99 [8]. ClinicalTrials.gov records list study contacts and locations for each trial [2].
Joining a trial is research participation, not treatment: most of these studies include a placebo arm, and the registry itself advises talking with a health care professional about the possible risks and benefits before joining [2, 5, 6, 7]. Whether a trial fits is a question for a clinician who knows your health history.
Is MariTide available by prescription?
No. MariTide is investigational and in Phase 3 testing, and it is not FDA approved [1, 2]. Amgen’s materials give no filing date or approval timeline [1, 2]. The only route to receiving it now is enrolling in a clinical trial, and most of those studies include a placebo arm [2, 5, 6, 7].
How much weight loss does MariTide cause?
There is no reported Phase 3 number yet. The MARITIME-1 record shows “No Results Posted,” so this page quotes no weight-loss figures [2]. The trial’s primary measure is percent change in body weight at week 72, with secondary measures for the shares of participants reaching 5%, 10%, 15%, and 20% weight loss [2].
Who is excluded from MariTide trials?
MARITIME-1 excludes people with type 1 or type 2 diabetes, a personal or family history of medullary thyroid carcinoma or MEN2, a history of pancreatitis, unstable major depressive disorder within two years, or a lifetime suicide attempt [2]. MARITIME-SWITCH also excludes people with prior obesity surgery or devices, a history of malignancy, or previous participation in a maridebart cafraglutide trial [4].
Sources
- Amgen. Amgen reports second quarter 2026 financial results. August 4, 2026.
- ClinicalTrials.gov. Evaluation of maridebart cafraglutide in adult participants without type 2 diabetes mellitus who have obesity or are overweight (NCT06858839).
- ClinicalTrials.gov. Clinical study record NCT06858878.
- ClinicalTrials.gov. Efficacy, safety and tolerability of switching from glucagon-like peptide-1 receptor agonists (GLP-1RA) to maridebart cafraglutide in adults with obesity or overweight (MARITIME-SWITCH) (NCT07575399).
- ClinicalTrials.gov. Evaluating the impact of maridebart cafraglutide on cardiovascular outcomes in participants with atherosclerotic cardiovascular disease and overweight or obesity (NCT07037433).
- ClinicalTrials.gov. Maridebart cafraglutide in heart failure with preserved or mildly reduced ejection fraction and obesity (NCT07037459).
- ClinicalTrials.gov. Maridebart cafraglutide versus placebo in adult participants with obstructive sleep apnea on positive airway pressure therapy (NCT07225686).
- Amgen. Clinical trials: find clinical trials.
- PR Newswire. Amgen reports second quarter 2026 financial results. August 4, 2026.
Frequently asked questions
Is MariTide FDA approved or available by prescription?
No. MariTide is an investigational drug in Phase 3 testing, and it is not approved by the FDA [1, 2]. Amgen's materials give no filing date or approval timeline [1, 2]. The only way to receive it currently is by enrolling in a clinical trial, and most trials include a placebo arm [2, 5, 6, 7].
How often is MariTide injected?
MariTide is a subcutaneous injection designed to start monthly, with maintenance possibly needing as few as 4 or 6 doses per year. The trials test monthly, every-eight-week, and quarterly schedules. Exact dose sizes and intervals are not public — trial arms use blinded labels such as high, medium, and low dose [2, 4].
How is MariTide different from Ozempic, Wegovy, Mounjaro and Zepbound?
Those approved medicines are weekly injections; Amgen describes them as weekly GLP-1 receptor agonists, specifically weekly semaglutide and weekly tirzepatide [1, 4]. MariTide is an antibody-peptide conjugate that activates the GLP-1 receptor and blocks the GIP receptor, given on a monthly or less frequent schedule. It is investigational and not FDA approved [1, 2].
What does GIP receptor antagonism mean?
Amgen states that MariTide activates the GLP-1 receptor and antagonizes the GIP receptor (GIPR) — meaning it blocks that receptor's action rather than stimulating it. How that blockade compares with the GIP activity of approved drugs is not described in Amgen's materials or the trial records, so this page does not draw that comparison [1, 2].
When will MariTide Phase 3 results come out?
The earliest pivotal data point is MARITIME-1's estimated primary completion date of 2027-01-21 (January 21, 2027). Registry dates are estimates that can move, and the record currently shows "No Results Posted". The heart trials are estimated to complete primary data collection on 2028-06-30 (June 30, 2028) [5, 6].
How much weight loss does MariTide cause?
There is no reported Phase 3 number yet. The MARITIME-1 record shows "No Results Posted," so this page quotes no weight-loss figures. The trial's primary measure is percent change in body weight at week 72, with secondary measures for the shares reaching 5%, 10%, 15%, and 20% weight loss.
Can I switch from Wegovy or Zepbound to MariTide in a trial?
MARITIME-SWITCH enrolls adults moving from a weekly GLP-1 receptor agonist to MariTide on an every-eight-week or quarterly schedule [1, 4]. Entry requires a BMI of at least 25, at least 10% weight loss on the weekly drug, and stable weight, dose, and gastrointestinal tolerability. Discuss the risks and benefits with a clinician before enrolling.
Who is excluded from MariTide trials?
MARITIME-1 excludes people with type 1 or type 2 diabetes, a personal or family history of medullary thyroid carcinoma or MEN2, a history of pancreatitis, unstable major depressive disorder within two years, or a lifetime suicide attempt. MARITIME-SWITCH also excludes people with prior obesity surgery or devices, malignancy history, or previous MariTide trial participation.
This article summarizes FDA labeling, published research and company information current as of September 14, 2026. It is not medical advice and does not replace a conversation with your own healthcare provider. How we research and verify.