Amgen discontinues Phase 1 obesity drug AMG 513, leaving MariTide as its only late-stage asset

Amgen discontinued development of AMG 513, an obesity drug in Phase 1 testing, on August 4, 2026, according to the company's second-quarter results. The decision leaves MariTide as Amgen's only obesity candidate in late-stage development ^[1].

One Phase 1 study of AMG 513 will continue so that people already enrolled can be followed through to completion ^[1]. Phase 1 is the first stage of human testing, typically focused on safety, tolerability and how a drug moves through the body. Such trials are small and are not designed to show whether a drug helps patients lose weight. Amgen has not disclosed a reason for stopping the program ^[1].

What Amgen still has

MariTide is now the company's only obesity asset in late-stage development ^[1]. Its Phase 3 MARITIME program covers chronic weight management, type 2 diabetes, cardiovascular outcomes, heart failure and obstructive sleep apnoea ^[1].

The concentration shows in Amgen's spending. Research and development costs rose 7% on a GAAP basis and 10% on a non-GAAP basis in the second quarter, which Amgen attributed to later-stage clinical programs, "primarily those related to MariTide," along with support for marketed products ^[2]. Total revenue rose 10% to $10.1 billion, GAAP earnings per share rose 65% to $4.37, and non-GAAP earnings per share rose 4% to $6.29, the company reported on August 4 ^[2]. Those figures cover the whole company, not obesity drugs specifically.

A crowded field

The move came in a month of competing news. On August 10, 2026, UK regulators authorised orforglipron, brand name Foundayo, for weight management and type 2 diabetes, making the UK the first country in Europe to approve the tablet ^[1]. In the United States, the FDA approved orforglipron for obesity in April 2026, and Lilly submitted it for type 2 diabetes during the second quarter ^[1]. Lilly also said its retatrutide data package is complete and that it plans to file with the FDA in the first quarter of 2027 ^[1]. Novo Nordisk's CagriSema is under FDA review for weight management, with a decision expected in late 2026 ^[1].

Amgen's release does not say whether AMG 513 was dropped because of safety findings, weak early signals or a shift in priorities, and it gives no timeline for a replacement candidate ^[1][2].

Why it matters for patients

AMG 513 was never available to patients, so nothing changes for anyone taking an approved obesity medicine today. The effects of a decision like this are further out: fewer early-stage candidates in testing can mean fewer choices later, though a single Phase 1 discontinuation does not by itself change what is on the market.

The people most directly affected are those already enrolled in the Phase 1 program. Amgen says one study will continue so participants can be followed to completion, but the company has not said how many people were enrolled, what the study measured or when follow-up ends ^[1].

The picture is different for MariTide. With AMG 513 gone, Amgen's obesity research spending and pipeline now rest on a single late-stage program ^[1][2]. Whether that program succeeds, and on what timeline, has not been disclosed beyond the list of conditions it covers ^[1].

What happens next

Amgen has not given a date for the continuing AMG 513 follow-up or said when any results from it will be reported ^[1].

The next obesity milestones on the calendar belong to other companies. The FDA decision on CagriSema is expected in late 2026 ^[1]. The Seventh Circuit hears oral arguments on September 24, 2026, in Lilly's appeal against the FDA over how retatrutide is classified, a question that affects how long its market exclusivity would run ^[1]. In the UK, the NICE appraisal of orforglipron is still open, with an expected publication date of November 18, 2026, and no second committee meeting scheduled ^[1].