Aleniglipron open-label extension reports 16.2% weight loss at 72 weeks

Structure Therapeutics said on Sept. 8, 2026, that participants taking the 180-mg dose of its experimental oral GLP-1 pill aleniglipron lost up to 16.2% of their body weight at 72 weeks, "with no evidence of a plateau in weight loss" ^[1]. The update came alongside early data on a second obesity drug, and analysts called the combined results a boost for the company's position in the oral obesity race ^[1].

The 72-week numbers come from an open-label extension of the Phase 2b ACCESS program, not from a new placebo-controlled trial. Structure also said fewer than 5% of participants across all dose groups stopped aleniglipron because of side effects, and that no off-target safety signals were seen ^[1].

How it compares on paper

Analysts at BMO Capital Markets wrote that the 72-week efficacy was "in line" with Novo Nordisk's Wegovy pill and "besting" Eli Lilly's recently launched Foundayo (orforglipron) ^[1]. For reference: Foundayo at 36 mg produced 12.4% weight loss at 72 weeks in the Phase 3 ATTAIN-1 trial, while oral semaglutide 25 mg (the Wegovy pill) produced 16.6% weight reduction at 64 weeks in the Phase 3 OASIS-4 trial ^[1]. Leerink Partners said the results "support potential best-in-class efficacy" ^[1].

Those are cross-trial comparisons, and they involve different trial designs, different patient groups, different time points and, importantly, different levels of evidence. The Foundayo and Wegovy pill figures come from Phase 3 randomized trials; the aleniglipron figure comes from an extension study in which everyone knew they were taking the drug ^[1].

There is also some nuance in how the 16.2% figure has been reported. In June 2026, Structure published the Phase 2b ACCESS results in Nature Medicine and described an interim open-label extension analysis in which participants kept losing weight after a median 20 weeks of follow-up beyond the 36-week double-blind period, reaching 13.3%, 16.2% and 15.3% for people who had been on 45 mg, 90 mg and 120 mg, respectively ^[2]. The September update attaches the 16.2% number to the 180-mg dose at 72 weeks ^[1]. The sources do not explain how those analyses relate to one another, and the full breakdown by dose at 72 weeks is not in the material provided.

On tolerability, the Nature Medicine data showed side effects typical of the GLP-1 class, mostly mild-to-moderate gastrointestinal events that decreased over time, with an overall discontinuation rate of 10.4% and most dropouts occurring during initial dose increases ^[2]. Structure said participants who paused or lowered their dose could often restart or go back up without vomiting recurring ^[2].

The second drug in the update

Structure also reported the first clinical data for ACCG-2671, an oral small-molecule amylin and calcitonin receptor agonist. In a Phase 1/2a single-dose study in healthy volunteers without obesity, the drug had a half-life of about six days, which the company said supports possible once-weekly dosing ^[1]. A single 10-mg dose produced a 3.3% average reduction in body weight; 5 mg produced 1.2%, 1 mg produced 0.9%, and the 2-mg group gained 0.1% ^[1]. Leerink flagged high rates of dose-related GI side effects, with nausea and vomiting in 60% to 100% of participants at the 5-mg and 10-mg doses, noting the study used no dose titration ^[1].

Why it matters for patients

Nothing about this changes what is available at the pharmacy today. Aleniglipron is an investigational drug that has not been approved by the FDA, and it is not something a clinician can prescribe.

The practical significance is longer-term. If a once-daily small-molecule pill can deliver weight loss in the range of injectable and peptide-based options, it could eventually add competition in a market where supply and cost have been persistent problems. Small-molecule pills are not made the same way as peptide drugs, and Structure has said its approach is designed to get around the scalability limits of peptides ^[2]. Whether that translates into lower prices or wider insurance coverage is not known.

The open-label design is a real limitation. Without a placebo group at 72 weeks, it is harder to know how much of the result reflects the drug itself.

What happens next

Structure started the Phase 3 ACCOMPLISH program in August 2026, with topline data expected in the second half of 2028, according to Leerink ^[1]. Any FDA filing would follow that, so the earliest realistic availability is years away. The Phase 3 program uses a 2.5-mg starting dose and is evaluating multiple doses based on the Phase 2 data and the company's end-of-Phase-2 meeting with the FDA ^[2].