Canvuparatide (MBX 2109) - (oPTimize)

Aug. 27, 2026: MBX Biosciences, Inc. (NASDAQ: MBX) announced first-patient dosing in the pivotal Phase 3 oPTimize trial (NCT07699471) of once-weekly canvuparatide (MBX 2109) for adults with chronic hypoparathyroidism.

The global, randomized, double-blind, placebo-controlled registrational study will enroll about 160 patients, randomized 3:1 to canvuparatide or placebo for 26 weeks, followed by a 78-week open-label extension. Dosing includes a 4-week fixed-dose period at 600 mcg weekly, an 18-week titration period up to 1,600 mcg weekly, and a 4-week maintenance period.

The primary endpoint at Week 26 is the proportion of patients achieving a composite response: normal albumin-adjusted serum calcium, independence from active vitamin D, calcium supplementation reduced to 600 mg/day or less, and no increase in study drug dose during the prior 4 weeks. Key secondary endpoints include normalization of urinary calcium excretion while maintaining normal serum calcium, plus improvements in physical functioning and hypocalcemia-related symptoms.

The Phase 3 trial follows positive Phase 2 Avail results and ongoing open-label extension data showing one-year clinical benefit, including normalization of serum calcium, reduced urinary calcium excretion, restoration of bone metabolism, and increased eGFR. Canvuparatide has FDA Orphan Drug Designation and EMA Orphan Designation for hypoparathyroidism.