Structure Therapeutics’ oral weight loss drug, aleniglipron, has prompted strong weight loss in a Phase II obesity trial – a result which analysts suggest could keep the drug in the running as a potential market competitor to Eli Lilly’s orforglipron.
During the mid-stage ACCESS study (NCT06693843), the oral glucagon-like peptide-1 receptor agonist (GLP-1RA) prompted a statistically significant placebo-adjusted weight loss of 16.3%, which was equivalent to 39lbs, at a 180mg dose after 44 weeks of treatment with the drug.
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This outcome was mirrored in the ACCESS study’s open-label extension (OLE) portion, in which patients taking aleniglipron continued to lose weight from 36 weeks on a 120mg dose, with reductions of up to 40.5lbs (16.2%) observed at the 52-week mark. Study operators have yet to observe evidence of a weight loss plateau in the ACCESS and the ACCESS OLE trials.
Alongside the drug’s promising efficacy profile, aleniglipron was proven safe and tolerable, with its profile mirroring that of the GLP-1RA class. The rate of treatment-emergent adverse event (TEAE)-related discontinuations was 3.4% in the aleniglipron arm in the ACCESS study, with the median patient follow-up time being 20 weeks.
Following the results of this study, Structure will continue its efforts to take aleniglipron to late-stage trials, with the biotech expecting to initiate Phase III clinical development for the drug in H2 2026.
Aleniglipron demonstrates “injectable-like efficacy”
In a 16 March statement detailing the results, Structure’s CEO, Raymond Stevens, noted that the data around aleniglipron’s Phase II programme demonstrates the drug’s “clear differentiation” profile from other oral GLP-1RAs like orforglipron.
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By GlobalDataStevens also touted the drug’s potential to become a “best-in-class oral GLP-1RA with injectable-like efficacy”.
While William Blair analyst, Andy Hsieh, has also taken a positive stance on this readout, he noted that it is likely “premature” to say that aleniglipron could be a best-in-class medicine that is clinically differentiated against Eli Lilly’s oral GLP-1RA, orforglipron, which is due a regulatory decision from the US Food and Drug Administration (FDA) in April 2026.
However, Hsieh notes that the “vast appetite for oral, small molecule GLP-1RAs, particularly in ex-US, middle or lower-income countries” presents a notable market opportunity for aleniglipron.
Senior GlobalData analyst, Shehroz Mahmood, believes that these results place aleniglipron at the “upper bound” of what the oral class has demonstrated to date in terms of efficacy, though differences in study duration, titration design, baseline patient characteristics, and estimand definitions trial design limit the reliability of indirect comparisons between aleniglipron and orforglipron.
When discussing tolerability, Mahmood said the results warrant a more cautious read. “The December 2025 results confirmed adverse event-related discontinuation rates of 10.4% across all active arms in the Phase IIb ACCESS study and 27.9% during the ACCESS II titration phase, both under a 5mg starting dose,” Mahmood said.
Though there was a near-zero discontinuation rate observed in the OLE study, Mahmood noted that these are difficult to interpret in isolation due to the study group primarily comprising patients who have already tolerated the initial titration. “The true tolerability profile of the 2.5mg initiation strategy will only be fully characterised in Phase III,” he added.
To capture a meaningful share of the oral GLP-1RA market, Mahmood said that aleniglipron will need to confirm that the 15-16% weight loss signal is durable over a longer treatment period across a broad population, while demonstrating that the 2.5mg starting dose translates into real-world adherence in Phase III. “The latter is likely the more commercially important question, as oral GLP-1RA therapies are being framed as potential maintenance therapies,” Mahmood added.
If aleniglipron were to gain approval, it would enter a market that GlobalData, parent company of Clinical Trials Arena, forecasts will exceed $173.5bn in value by 2031.
