AstraZeneca starts three SELENE Phase 3 trials for the amylin analog AZD6234

AstraZeneca has started three Phase 3 trials of AZD6234, an experimental amylin analog for obesity, with all three registered within days of each other in August 2026. The program, called SELENE, includes one trial aimed squarely at a group that has been largely overlooked in late-stage obesity research: people who are already on an incretin medication such as semaglutide or tirzepatide.

The three studies are SELENE 1, with a planned enrollment of about 2,500 participants; SELENE 2, with about 1,500; and SELENE 3, with about 500. One of the registry records, NCT07784725, describes a study evaluating the effect of AZD6234 in adult participants with obesity, or overweight with a weight-related health condition, who do not have type 2 diabetes ^[1]. A second SELENE record has been posted under NCT07776509 ^[2].

SELENE 3 is the one that stands out. Rather than enrolling people starting obesity treatment for the first time, it is designed to test AZD6234 on top of an incretin drug that participants are already taking. That makes it one of three Phase 3 programs launched in 2026 that focus on patients already using GLP-1 medicines rather than new starts — a shift that reflects how many people are now years into treatment and looking for what comes next.

Amylin analogs work through a different hormone pathway than GLP-1 receptor agonists like semaglutide (Ozempic, Wegovy, Rybelsus) or the dual agonist tirzepatide (Mounjaro, Zepbound). That is the basic rationale for testing one as an add-on: if the mechanisms are different, the effects might stack. Whether they actually do, and at what cost in side effects, is exactly what SELENE 3 is built to answer.

A note on what these sources do and do not show. The publicly posted registry pages confirm the studies exist and identify the population in broad terms ^[1][2], but the detailed study design — primary endpoints, dose levels, dosing schedule, trial duration, comparator arms, the specific incretin drugs allowed in SELENE 3, country and site lists, and the estimated primary completion dates — is not contained in the source text available for this report. Those details are not yet confirmed here and should not be assumed.

Why it matters for patients

Most Phase 3 obesity trials to date have enrolled people who were not already on a GLP-1 drug. That leaves a practical gap: millions of Americans are currently on semaglutide or tirzepatide, and many have hit a weight plateau, are dealing with side effects, or want to know whether adding a second medicine helps. Trials like SELENE 3 are the first large, randomized efforts designed to produce evidence for that exact situation instead of extrapolating from studies in treatment-naive patients.

It also matters for what eventually shows up on a label. If a drug is only ever tested in people starting fresh, its FDA-approved use is likely to be framed that way, and combination use ends up happening off-label without trial data behind it. Testing add-on use up front is how combination therapy gets an evidence base — and how insurers eventually get something to point to when deciding coverage.

The practical caveat is time. Phase 3 obesity programs typically run for a year or more before topline results, then go through regulatory review. Nothing about the SELENE launch changes what is available at a pharmacy today, and AZD6234 is not approved by the FDA for any use.

What happens next

The three SELENE trials began enrolling in August 2026 ^[1][2]. Completion dates and the timing of any results readouts are not stated in the available source material. Anyone tracking the program can follow the registry records at NCT07784725 ^[1] and NCT07776509 ^[2] for updates to enrollment status, site locations and study timelines.