MBX Biosciences announced that both the rationale and design of the Phase 2 Avail trial of MBX 2109, the Company’s potential long-acting parathyroid hormone peptide prodrug, in adults with hypoparathyroidism were featured in a poster presentation at the American Society for Bone and Mineral Research 2024 Annual Meeting held in Toronto, ON, Canada September 27-30, 2024. MBX 2109 is an investigational, PTH peptide prodrug designed as a once-weekly PTH replacement therapy with the potential to normalize serum calcium levels, reduce the need for active vitamin D and calcium supplementation, and improve patient convenience and treatment adherence. The Phase 2 Avail trial is a randomized, multicenter, 12-week, double-blind, placebo-controlled study evaluating the safety, pharmacokinetics, and efficacy of MBX 2109 in approximately 48 adults with HP. The primary endpoint of the Phase 2 clinical trial is the proportion of patients who can discontinue active vitamin D and reduce calcium supplements to less than or equal to 600 mg per day after 12 weeks of treatment while maintaining normal serum albumin-adjusted calcium levels. Secondary endpoints include safety and tolerability of MBX 2109 and characterization of its pharmacokinetics and pharmacodynamic activity and the impact on quality of life using patient-reported outcome tools. The trial begins with an optimization period of up to 4 weeks in which doses of calcium, vitamin D, and/or magnesium supplements are adjusted to achieve normal serum calcium levels. Participants completing the optimization period are then randomized 1:1:1:1 to receive weekly doses of placebo or MBX 2109 at 400, 600, or 800 undefined for 12 weeks. The treatment period is comprised of a 4-week fixed-dose period and an 8-week titration period. During the 8-week dose-adjustment period, doses of MBX 2109 and active vitamin D and calcium supplements are adjusted according to a prespecified protocol algorithm to reduce risk of hypo- or hypercalcemia. Participants completing the 12-week treatment period may enroll in a long-term, open-label extension study. Participants who received MBX 2109 will maintain their existing dosage from the 12-week trial while patients on placebo will transition to MBX 2109 at the 400 undefined dose. The first patient in the study was dosed in August 2024. The study is actively enrolling, and topline study results are expected to be available in the third quarter of 2025.