A new medication called MariTide is showing promise for weight loss, according to results from a phase 2 clinical trial posted on June 23.
People with obesity who took the drug, which is manufactured by Amgen, lost up to 16% of their body weight over 52 weeks. Among participants with both obesity and type 2 diabetes, MariTide led to both weight loss and improvements in glycated hemoglobin (HbA1C) levels, too.
MariTide is a glucagon-like peptide-1 (GLP-1) drug, similar to blockbuster medications Ozempic and Wegovy (semaglutide), and Mounjaro and Zepbound (tirzepatide).
What sets this new medication apart, though, is that MariTide also contains a “peptide-antibody conjugate molecule,” which extends the drug’s effects. As such, it can be administered once a month.
Semaglutide and tirzepatide are effective, but many people struggle to access and adhere to the once-weekly injections. A less-frequent injection could make it easier for patients to stick with their GLP-1, reducing barriers and boosting long-term health outcomes.
Though it’s not clear when the medication might be available, “this is a great additional agent to have in our approach to obesity and diabetes [treatment],” Ajaykumar Rao, MD, associate professor and chief of endocrinology, diabetes, and metabolism at the Temple University Lewis Katz School of Medicine, told Health. “The monthly aspect of this is very appealing.”
For this clinical trial, researchers enrolled 592 people, all of whom had obesity. 127 participants had type 2 diabetes, too.
Over the course of a year, the participants received either a placebo or one of three monthly doses of MariTide—140 milligrams (mg), 280 mg, or 420 mg.
A handful of the participants being treated for obesity alone received lower starting doses that gradually increased over four or 12 weeks.
In the end, 72% of the participants completed the trial, and 28% dropped out. Results showed, on average:
- 16.2% body weight reduction for all participants with obesity but without diabetes
- 19.9% body weight reduction, excluding participants with obesity who discontinued the drug
- 12.3% body weight reduction for all participants with obesity and diabetes
- 17% body weight reduction, excluding participants with obesity and diabetes who stopped taking the drug
The medication was also linked to improvements in blood pressure, inflammation markers, and lipid levels, and up to a 2.2 percentage point improvement in A1C levels.
In general, these phase 2 results are “very exciting to see,” Rao said.
For now, MariTide has not been tested against other GLP-1 drugs such as semaglutide or tirzepatide, Rao said. However, this early data suggests it may be comparable.
In clinical trials, semaglutide led to a 14.9% reduction in body weight, while tirzepatide led to a 20.9% body weight reduction.
Side effects for MariTide also seem to be on par for those associated with Ozempic, Mounjaro, and other GLP-1 drugs.
Participants most commonly reported mild-to-moderate gastrointestinal issues, including:
These symptoms typically occurred during the first few doses and, in general, were less common among those who started on a lower MariTide dose.
There are two key elements of MariTide’s structure that explain why it may be able to deliver such significant weight loss and metabolic benefits.
For one, MariTide contains a GLP-1 receptor agonist, which mimics the hormone GLP-1. This suppresses appetite, delays gastric emptying, and enhances insulin production.
It also contains a glucose-dependent insulinotropic polypeptide (GIP) receptor antagonist, which helps regulate another hormone, incretin, to control blood sugar, research shows.
MariTide isn’t the only weight loss drug that acts on both GLP-1 and GIP receptors—tirzepatide does as well.
But MariTide contains a monoclonal antibody which deactivates or “down-regulates” the GIP receptor, said Meghan Garcia-Webb, MD, an obesity medicine, internal medicine, and lifestyle medicine physician based in Massachusetts. On the other hand, tirzepatide activates the GIP receptor.
Research suggests that both GIP receptor activation and deactivation lead to weight loss, Garcia-Webb told Health.
But MariTide’s different formulation “allows the active compound to remain in the bloodstream at therapeutic levels for longer intervals, thereby supporting less frequent administration without sacrificing clinical effectiveness,” Sean Bourke, MD, obesity medicine physician and founder of JumpstartMD, told Health.
MariTide has a 21-day half-life—that’s three times as long as the once-weekly GLP-1 drugs currently approved by the FDA. As such, it can potentially be taken monthly, or perhaps every three weeks, added Wajahat Mehal, MD, DPhil, director of the Metabolic Health and Weight Loss Program at Yale Medicine.
According to the researchers, MariTide’s less-frequent injection schedule could improve medication adherence and improve weight maintenance and metabolic health long-term.
However, it’s too soon to say how MariTide might work in the real world. There are still many questions that remain.
For one, future research should look into why so many people didn’t complete the trial, Mehal told Health. “There was a very high drop out rate in the clinical trials, which did not appear to be due to reported side effects. So [this] is a bit of a puzzle,” he said.
Plus, the phase 2 trial data hasn’t been fully released. Several participants have been enrolled in part 2 of the study, which is investigating MariTide’s effects beyond 52 weeks. Researchers are also examining what longer-term weight maintenance might look like with the medication.
After the part 2 data comes out, all eyes will be on the phase 3 trial—this final leg of testing will confirm the efficacy and safety of MariTime in a larger participant pool over 72 weeks.
Phase 3 testing will also ramp up the dosage of MariTime more gradually, which may help mitigate some of the side effects patients reported. Additional trials will also examine the drug’s effect on people with various comorbidities, including cardiovascular disease, heart failure, and obstructive sleep apnea.
After that, the Food and Drug Administration will review all of the available evidence. Rao said he expects the drug will eventually be approved, but it’s unclear when that might happen. If the evidence holds up, Bourke said we may see MariTide on the market within two to three years.
“Nevertheless, confirmation of these outcomes through phase 3 trials is necessary before any conclusions can be drawn regarding its ultimate role in clinical practice,” Bourke said.
