Structure Therapeutics Inc. announced positive results from the Phase 1b multiple ascending dose (MAD) study of its highly selective oral GLP-1 receptor agonist, GSBR-1290, in healthy overweight or obese individuals. In the 28-day study, GSBR-1290 demonstrated significant weight loss supporting once-daily (QD) dosing and an encouraging safety and tolerability profile. The Phase 1b MAD study focused on the safety and tolerability of GSBR-1290 in 24 healthy overweight or obese individuals.

Participants were randomized 3:1 to GSBR-1290 or placebo across three dose cohorts with target doses of 30mg, 60mg or 90mg. GSBR-1290 demonstrated reductions in mean body weight ranging up to 4.9 kg compared to baseline, and up to 4.9% placebo-adjusted. GSBR-1290 demonstrated an encouraging safety and tolerability profile following once-daily dosing.

No participants discontinued the study drug due to adverse events. The majority of adverse events reported were mild, with no severe or serious adverse events observed. As expected for this class, leading adverse events were gastrointestinal-related, with the two most common adverse events being nausea and vomiting, with higher incidences observed in the 60 and 90 mg dose cohorts compared to placebo.

There were no clinically meaningful changes in liver function tests. A data collection omission occurred at a clinical site that impacted the obesity cohort (120 mg dose level) of the Phase 2a study, where weight was not collected at the final (week 12) visit for 24 of the 40 enrolled participants. Other safety and laboratory assessments were measured at all visits, including the week 12 visit as per protocol.

Structure will enroll additional participants in the Phase 2a obesity cohort to replace those for whom 12-week weight data was not collected. The replacement participants will follow the same study protocol, without changes in the titration schema or target dose (120 mg/QD). As a result, Structure now plans to report topline data from the obesity cohort in the first half of 2024.

While Structure remains blinded to data from the Phase 2a obesity cohort, there were no adverse-event related discontinuations through the end of the study at 12 weeks for any of the 40 participants in the Phase 2a obesity cohort. Structure remains on track to report topline data from the type 2 diabetes cohort of the Phase 2a study in the latter half of the fourth quarter of 2023 as planned, along with results from the Japanese ethno-bridging study of GSBR-1290. Structure continues to plan to initiate two Phase 2b studies of GSBR-1290 in 2024.

The type 2 diabetes study is expected to include approximately 500 individuals across the United States, Europe and Japan. The obesity study is expected to include approximately 275 individuals across the United States and Europe. In preparation for the Phase 2b studies, Structure is also planning a separate formulation bridging PK study to support the planned transition from capsules to tablets, which is expected to initiate in the fourth quarter of 2023 and complete in the second quarter of 2024.

Pending supportive data from this bridging study, the tablet formulation would be used in future GSBR-1290 studies starting with the planned Phase 2b studies.