MBX Biosciences Doses First Patient in Phase 3 oPTimize Trial of Canvuparatide

Carmel, Indiana and Burlington, Massachusetts – August 27, 2026

MBX Biosciences Initiates Phase 3 oPTimize Trial

The Phase 3 oPTimize trial (NCT07699471) is a global, multicenter, randomized, double-blind, placebo-controlled study evaluating once-weekly canvuparatide in adults with chronic hypoparathyroidism. Approximately 160 patients will be randomized 3:1 to receive canvuparatide or placebo during the 26-week double-blind treatment period, followed by a 78-week open-label extension. Patients will receive canvuparatide using the same device intended for commercial use. The initial treatment period includes a four-week fixed-dose phase at 600 micrograms once weekly, an 18-week individualized dose-titration period allowing doses up to 1,600 micrograms once weekly, and a four-week maintenance period without increases in study drug, active vitamin D or calcium supplementation. The trial is designed to provide the pivotal efficacy and safety data needed to evaluate canvuparatide’s potential for registration in chronic hypoparathyroidism.

Canvuparatide Targets PTH Replacement in Hypoparathyroidism

Canvuparatide is an investigational long-acting PTH peptide prodrug designed to provide continuous, infusion-like exposure to active PTH through a once-weekly subcutaneous injection. The primary endpoint of the oPTimize study will assess the proportion of patients achieving a composite response at Week 26, requiring maintenance of normal albumin-adjusted serum calcium, independence from active vitamin D, reduction of calcium supplementation to ≤600 mg per day, and no study-drug dose increases during the four weeks before assessment. Key secondary endpoints include normalization of urinary calcium excretion in patients with elevated baseline levels while maintaining normal serum calcium, as well as improvements in physical functioning and hypocalcemia-related symptoms. The study will additionally evaluate bone mineral metabolism, kidney health, bone biomarkers, patient-reported outcomes and long-term safety. The Phase 3 program builds on Phase 2 Avail™ and extension-study findings that MBX says were consistent with restoration of systemic PTH activity.

MBX Advances Canvuparatide Toward Potential Registration

The Phase 3 initiation represents a major development milestone for canvuparatide (MBX 2109) and moves the program from proof-of-concept into pivotal development. Hypoparathyroidism is characterized by deficient or absent PTH production, resulting in hypocalcemia and disrupted mineral homeostasis. Current standard treatment primarily relies on calcium supplements and active vitamin D, which do not directly replace the missing hormone. MBX is therefore developing canvuparatide as a potential replacement therapy intended to restore more continuous PTH activity with a convenient weekly dosing schedule. Canvuparatide has received FDA Orphan Drug Designation and EMA Orphan Designation for hypoparathyroidism. However, the therapy remains investigational, and the positive Phase 2 results do not establish that the pivotal trial will succeed. The Week 26 composite responder endpoint, urinary calcium outcomes, functional measures and long-term safety will be critical in determining whether canvuparatide can support a future regulatory application and establish a meaningful role in chronic hypoparathyroidism treatment.

Source:MBX Biosciences,,press relese