Amgen Launches Late-Stage Obesity Trial in Patients Who Switch From Rival Drugs

Why It Matters

The trial could break the current duopoly of Lilly and Novo Nordisk, offering patients and payers a new option and potentially reshaping revenue dynamics in the $10 billion U.S. obesity‑drug market.

Key Takeaways

• MariTide's Phase III trial enrolls 1,200 patients switching from GLP-1s
• Primary endpoint: 10% body weight loss at 68 weeks
• Study includes safety comparison against semaglutide and tirzepatide
• Amgen aims to capture patients dissatisfied with existing GLP-1 side effects
• Success could diversify obesity market beyond Lilly and Novo Nordisk

Pulse Analysis

The global obesity crisis continues to drive unprecedented demand for pharmacologic interventions, with the GLP‑1 class now accounting for the bulk of new prescriptions. Eli Lilly’s semaglutide (Wegovy) and Novo Nordisk’s tirzepatide (Mounjaro) have together captured more than $10 billion in U.S. sales, setting a high bar for efficacy and safety. Yet clinicians report a subset of patients experiencing gastrointestinal side effects or inadequate weight loss, creating a niche for alternative agents that can either complement or replace existing therapies.

Amgen’s response is MariTide, a long‑acting peptide that targets the glucagon‑like peptide‑1 receptor while adding a novel fatty‑acid chain to extend half‑life. The company announced three Phase III studies, the most notable enrolling roughly 1,200 adults who have previously been on semaglutide or tirzepatide and are now switching to MariTide. The primary efficacy endpoint is a minimum 10 percent body‑weight reduction after 68 weeks, with secondary measures tracking cardiovascular safety, tolerability, and quality‑of‑life scores. By directly comparing outcomes against the market leaders, Amgen hopes to demonstrate a differentiated risk‑benefit profile.

If MariTide meets its targets, the drug could open a new revenue stream for Amgen and intensify competition in a market that has been largely duopolistic. Payers may welcome a therapy that reduces the incidence of nausea or offers a more convenient dosing schedule, potentially expanding insurance coverage. For patients, a viable alternative could mean better adherence and sustained weight loss, addressing a critical unmet need. Investors will be watching the trial readouts closely, as success could reshape the obesity‑treatment landscape and spur further innovation.