Amgen Launches Phase 3 Trials for Obesity Drug MariTide, Advancing Maritime Program

Amgen, the California-based pharmaceutical giant, has initiated two pivotal phase 3 clinical trials for its lead obesity treatment, MariTide, marking a significant milestone in the company's Maritime program. The announcement, made by Amgen's R&D head Jay Bradner, M.D., at the TD Cowen Health Care Conference, sheds light on the company's ambitious plans in the competitive obesity drug market.

Maritime Program Sails into Late-Stage Development

The Maritime program comprises two key studies: Maritime-1 and Maritime-2. Maritime-1 aims to enroll 3,500 participants living with obesity or overweight without Type 2 diabetes. Concurrently, Maritime-2 will recruit 999 individuals with obesity or overweight who also have Type 2 diabetes. Both trials are expected to yield primary readouts in early 2027.

These placebo-controlled studies will evaluate three different doses of MariTide, with the primary endpoint measuring the percent change from baseline in body weight at 72 weeks. While specific dosing details remain undisclosed, Bradner confirmed that both trials will employ dose escalation strategies.

MariTide: A Potential Game-Changer in Obesity Treatment

MariTide, Amgen's most advanced obesity asset, is a monoclonal antibody linked to peptides designed to enhance GLP-1 receptor activity while reducing GIP receptor activation. The drug's promise was evident in phase 2 results released in November, which demonstrated average weight loss of up to 20% over 52 weeks in patients receiving monthly doses.

The phase 2 trial, involving 592 adults, tested monthly doses of 140 mg, 280 mg, and 420 mg, as well as an eight-week 420 mg regimen. Notably, the 280 mg monthly dose group achieved the highest weight loss, with no observed plateau, suggesting potential for further weight reduction beyond the 52-week mark.

Industry analysts have drawn comparisons between MariTide and Eli Lilly's weekly injectable Zepbound (tirzepatide), noting that MariTide's primary differentiation appears to be its monthly dosing frequency. However, Bradner hinted at the possibility of head-to-head trials against approved weight loss drugs, though no concrete plans were announced.

Challenges and Setbacks in Amgen's Obesity Pipeline

Despite the progress with MariTide, Amgen's obesity drug development efforts have faced challenges. In May 2024, the company discontinued AMG 786, an early-stage obesity candidate, to focus resources on MariTide. More recently, Amgen's other clinical obesity prospect, AMG 513, was placed on a clinical hold by the FDA, affecting an ongoing phase 1 trial. The company maintains that the issue is unlikely to be drug-related but has not disclosed further details about AMG 513's mechanism of action.

These setbacks, coupled with a data disclosure incident last November that temporarily impacted Amgen's market valuation, underscore the high-stakes nature of obesity drug development. The incident involved the inadvertent release of bone density change data from a phase 1 MariTide trial, highlighting the intense scrutiny faced by companies in this competitive therapeutic area.