Amgen kicks off two pivotal Phase 3 trials for MariTide as it aims to capture the booming obesity drug market.

Amgen has moved forward with two late-stage trials of its experimental obesity drug MariTide, marking a pivotal step for the company as it aims to enter the rapidly expanding obesity-treatment market. The trials are part of the MARITIME program, designed as Phase 3 studies to evaluate weight loss outcomes over an extended period. Dr. Jay Bradner, Amgen’s executive vice president of research and development, described the progression of the MARITIME program as progressing “very, very well” during a TD Cowen conference, signaling confidence in MariTide’s advancement. MariTide is positioned as a monthly injection intended to compete with established weekly GLP-1 therapies from Novo Nordisk and Eli Lilly. These drugs belong to the GLP-1 class, which mimics gut hormones to suppress appetite and help regulate blood sugar. The weight loss market, driven by GLP-1 therapies, has drawn substantial investor interest as analysts project substantial growth ahead. At the same time, the broader market expects continued development of new mechanisms that could offer alternative approaches to weight management and metabolic health.

Overview of the MARITIME program and the Phase 3 trials

The MARITIME program comprises two pivotal Phase 3 trials that Amgen has initiated to evaluate MariTide’s efficacy and safety in diverse populations affected by obesity and overweight conditions. One trial is designed to enroll approximately 3,500 participants who are obese or overweight but do not have Type 2 diabetes, aiming to assess weight loss outcomes in this no-diabetes cohort. The second trial targets 999 patients who are obese or overweight and also have Type 2 diabetes, seeking to determine how MariTide performs in a population with a common comorbidity that influences metabolic health. The central objective shared by both studies is to quantify the percentage of weight loss achieved at 72 weeks, a clinically meaningful horizon that aligns with the expectations of regulators and industry observers for long-term efficacy.

In these trials, Amgen plans to test three target doses of MariTide, employing a dose-escalation approach. Dose escalation means patients begin treatment at a lower dose and then have their dosage increased over time, a strategy designed to identify an optimal balance between efficacy and tolerability across the population. The company has not disclosed a specific dosing schedule for the trials, choosing to withhold a precise regimen as the study designs unfold and more data become available. The trial design reflects a careful emphasis on long-term weight management, a hallmark of the GLP-1 class’s therapeutic narrative, which focuses not only on initial weight loss but on sustained outcomes over extended periods.

Amgen’s late-stage efforts build on earlier clinical signals from MariTide. In November, Amgen reported that MariTide helped patients with obesity lose up to 20% of their weight on average after one year in a Phase 2 trial, with no observed weight loss plateau. In the same Phase 2 program, patients who were obese and had Type 2 diabetes achieved weight losses of up to 17% after one year, also without a plateau. While these Phase 2 results were encouraging, they were viewed as modest relative to some Wall Street expectations for the drug’s ultimate performance in the broader market. These Phase 2 outcomes set the stage for the larger, more definitive Phase 3 trials and helped inform expectations around the durability of MariTide’s effects across different metabolic backgrounds.

Amgen has indicated that more data on MariTide will emerge during the current year. The full results from the Phase 2 trial were slated for presentation at the American Diabetes Association conference in June, and the company also noted that an extension component of that trial would yield a readout in the second half of the year. These upcoming data readouts carry considerable weight for investors and analysts who will be looking for corroborating signals about efficacy, durability, and safety before forming broader expectations about MariTide’s potential trajectory in the obesity-drug arena.

MariTide represents a novel mechanism within the obesity drug landscape. It is described as a peptide antibody conjugate, meaning the compound combines a monoclonal antibody with two attached peptides. The peptides in MariTide are designed to activate receptors of GLP-1, a hormone that helps regulate appetite and glucose metabolism, while the antibody component blocks receptors of another hormone called GIP (glucose-dependent insulinotropic peptide). This dual-action approach stands in contrast to some competing therapies and represents Amgen’s effort to carve out a distinct pharmacologic niche within the GLP-1/GIP framework. By exploring both activation of GLP-1 pathways and blockade of GIP signaling, MariTide aims to influence energy balance and metabolic regulation in a manner that could yield meaningful, durable weight loss results.

Market context and competitive landscape

The market environment for obesity drugs has grown rapidly as GLP-1 therapies have gained traction due to their robust weight loss effects and favorable metabolic benefits. As of May, surveys indicated that roughly 6% of U.S. adults, translating to more than 15 million people, were using a prescription GLP-1 medication to address obesity or related metabolic concerns. This significant patient uptake underscores the potential demand for new agents that can deliver superior efficacy, tolerability, or convenience. Analysts have forecast that the GLP-1 market could surpass $150 billion in annual sales by the early 2030s, underscoring the financial incentives for companies developing innovative obesity therapies.

Amgen’s MariTide faces notable competition from established and emerging therapies. Eli Lilly’s Zepbound (a monoclonal antibody targetingGIP and GLP-1 pathways) operates in a similar therapeutic space by activating both GIP and GLP-1 receptors, thereby influencing appetite and energy balance through dual signaling. Novo Nordisk’s Wegovy, by contrast, activates GLP-1 receptors without targeting GIP, focusing on GLP-1–driven mechanisms to promote weight loss. The differing receptor targets among these drugs highlight a spectrum of potential metabolic effects, including how the body processes sugar and fat, which remains a topic of active investigation in obesity pharmacology. MariTide’s unique dual mechanism — GLP-1 activation via peptide components and GIP receptor blockade via the antibody — positions it as a distinct entrant that could offer different therapeutic advantages or safety considerations relative to the current leaders.

Beyond the receptor-level distinctions, the broader strategic landscape includes ongoing efforts to optimize dosing, improve patient adherence, and expand indications. Amgen’s approach with a monthly injectable contrasts with the weekly administration schedules typical of some competing GLP-1 therapies, potentially offering a convenience benefit that could translate into improved real-world effectiveness. Investors and observers will watch how MariTide’s clinical performance translates into commercial potential, particularly as Phase 3 data mature and regulatory decisions approach. The evolving competitive dynamics are shaping how downstream price, access, and reimbursement could unfold for new entrants into the obesity-treatment market.

Phase 2 results and implications for Phase 3

Phase 2 data for MariTide established a signal that the drug can produce meaningful weight loss in obesity populations. In the obesity-only cohort without Type 2 diabetes, average weight reduction reached as high as 20% after about a year of therapy, with patients showing no plateau in weight loss over the observed period. For participants who were obese or overweight and also had Type 2 diabetes, the Phase 2 results demonstrated weight losses of up to 17% after one year, again with no plateau observed. While these findings were encouraging, they were perceived as falling short of some Wall Street expectations, contributing to a cautious but positive investor sentiment about the prospects of MariTide in Phase 3.

Interpretation of these Phase 2 outcomes suggests that MariTide has the potential to deliver substantial, sustained weight loss across diverse metabolic states. The absence of a plateau in both cohorts is particularly noteworthy, as durability of effect is a critical consideration for long-term obesity treatments. The data also provide a foundation for the Phase 3 program’s design, reinforcing the choice to pursue a 72-week weight-loss endpoint and to explore multiple dosing regimens. Nevertheless, the Phase 2 results carry limitations inherent to early-stage trials, including smaller sample sizes and shorter observation windows relative to a full Phase 3 program. Amgen’s ongoing Phase 3 trials aim to validate these signals in larger and more diverse populations, while also clarifying safety and tolerability profiles across longer treatment durations.

From an investor perspective, the Phase 2 signals implied that MariTide could reach clinically meaningful weight loss levels that meet or surpass regulatory expectations if the Phase 3 data replicate and extend these findings. The company’s decision to advance two large, long-term Phase 3 studies across different metabolic contexts reflects an emphasis on robust efficacy signals and generalizability. As Amgen prepares to present additional data later in the year, market participants will be attentive to how the Phase 3 results align with the Phase 2 experience, particularly regarding the consistency of weight loss across dosing regimens and patient subgroups. The timing of data readouts, including the ADA conference presentation for Phase 2 and the second-half extension readout, will contribute to a clearer view of MariTide’s potential trajectory in the competitive obesity-drug space.

Data readouts, regulatory considerations, and near-term expectations

Amgen has signaled that further data on MariTide are anticipated within the current year, a development that could shape investor sentiment and future strategic planning. The full Phase 2 trial results were slated for a presentation at the American Diabetes Association conference in June, providing the broader medical community with a comprehensive look at efficacy and safety signals observed in the earlier study. In addition to the ADA presentation, Amgen is continuing to study participants in an extension arm of the Phase 2 trial, with the readout expected in the second half of the year. These data releases are essential for informing the ongoing Phase 3 program and for supporting any eventual regulatory submissions should the Phase 3 trials demonstrate favorable outcomes.

From a regulatory perspective, the Phase 3 program is designed to meet the evidentiary standards required to demonstrate durable, clinically meaningful weight loss and acceptable safety profiles over an extended treatment horizon. The 72-week primary endpoint aligns with regulatory expectations for assessing sustained efficacy, while the exploration of three dose levels and the dose-escalation strategy aims to identify an optimal regimen that balances efficacy with tolerability. The MD/DI (medical device and diagnostic information)-adjacent considerations that accompany such therapies include long-term safety assessments, immunogenicity, and real-world adherence patterns, all of which are typically scrutinized during the regulatory review. While the current description focuses on efficacy endpoints, the broader regulatory path will depend on comprehensive safety data across diverse populations, including those with comorbid conditions such as Type 2 diabetes.

Mechanistically, MariTide’s design as a peptide antibody conjugate marks an innovative approach within the obesity drug landscape. The linked peptides engage GLP-1 receptor signaling, a pathway well established in promoting weight loss and improving glycemic control. In parallel, the antibody component blocks GIP receptors, adding a counter-regulatory dimension that could influence energy balance and nutrient handling in novel ways. The interplay between these dual actions may yield distinct clinical outcomes compared with agents that solely activate GLP-1 pathways or those that target GIP signaling alone. As Amgen prepares for subsequent data releases, stakeholders will be assessing whether this dual mechanism translates into superior or more durable weight loss and whether safety signals remain favorable over longer treatment durations.

Mechanism details: the peptide antibody conjugate and receptor targets

MariTide’s mechanism centers on a novel peptide antibody conjugate. The therapy integrates a monoclonal antibody with two attached peptides, a formulation designed to orchestrate receptor activity in the gut’s regulatory system. The peptides are intended to activate GLP-1 receptors, which play a pivotal role in suppressing appetite and modulating glucose metabolism. Concurrently, the antibody component is designed to block receptors for GIP, another gut-derived hormone that influences insulin release and energy storage. This combination creates a dual-action pharmacologic profile that diverges from traditional GLP-1–only therapies and from agents that target GIP alone. By engaging both GLP-1 and GIP pathways through distinct molecular components, MariTide seeks to harness complementary mechanisms that may yield enhanced weight loss or metabolic benefits for patients with obesity and related conditions.

In direct contrast to competitors, Eli Lilly’s Zepbound integrates a mechanism that activates both GIP and GLP-1 pathways, whereas Novo Nordisk’s Wegovy engages GLP-1 receptors without targeting GIP. MariTide’s design, focusing on GLP-1 activation via the peptides while specifically blocking GIP receptors through the antibody, suggests a different pharmacodynamic profile that could translate into unique efficacy and safety patterns. This structural and functional distinction is central to Amgen’s messaging about MariTide’s potential to offer a differentiated therapeutic option for obesity management and metabolic health. The ongoing Phase 3 program will be the definitive test of whether this dual-action approach delivers meaningful clinically important weight loss and favorable long-term outcomes relative to existing therapies.

As the clinical program continues, stakeholders will closely monitor how the pharmacology translates into real-world effectiveness, tolerability, and adherence. The potential for a monthly dosing schedule could present a practical advantage in daily life for patients who require sustained treatment over extended periods. However, as with all novel metabolic therapies, long-term safety data will be critical to ensuring that benefits outweigh potential risks in diverse patient populations. Amgen’s forthcoming data releases, including Phase 2 results and the ongoing Phase 3 readouts, will be instrumental in shaping the narrative around MariTide’s role in the evolving obesity-drug landscape and its potential to reshape how clinicians approach weight management and metabolic health.

Conclusion

Amgen’s initiation of two Phase 3 trials for MariTide under the MARITIME program marks a significant advancement in the company’s obesity-drug strategy. The trials, which examine three target doses across populations with and without Type 2 diabetes, aim to measure weight loss at 72 weeks and to determine whether a dose-escalation approach can yield durable, clinically meaningful outcomes. MariTide’s mechanism — a peptide antibody conjugate that activates GLP-1 receptors while blocking GIP receptors — positions it as a distinctive entrant in a market dominated by competing therapies that either target GLP-1 alone or engage both GIP and GLP-1 pathways. The Phase 2 results indicated substantial weight losses with no plateau, albeit not meeting all Wall Street expectations, and the industry will be watching how the Phase 3 data unfold, along with forthcoming ADA conference presentations and extension-readout results later in the year. The broader market context remains highly favorable for obesity drugs, with a growing patient base and an anticipated multi-decade growth trajectory that could exceed $150 billion annually by the early 2030s. If MariTide confirms durable efficacy and a favorable safety profile in Phase 3, Amgen could secure a meaningful position in a rapidly evolving therapeutic area that has substantial implications for public health and metabolic disease management.