MBX Biosciences doses first patient in Phase 3 trial of canvuparatide for hypoparathyroidism

MBX Biosciences announced on August 27, 2026 that the first patient has been dosed in its pivotal Phase 3 oPTimize clinical trial evaluating once-weekly canvuparatide for the treatment of chronic hypoparathyroidism (HP)¹.

The study, registered as NCT07699471, is set up as a global, multicenter, randomized, double-blind, placebo-controlled study, followed by a 78-week open-label extension¹. The company said approximately 160 patients will be enrolled and randomized 3:1 to receive canvuparatide or placebo during the 26-week double-blind treatment period¹, and canvuparatide will be given once weekly using the same device planned for commercial use¹.

Dosing within the 26-week period is structured in three stages: a four-week fixed-dose period at 600 micrograms or placebo once weekly, an 18-week individualized dose-titration period of up to 1,600 micrograms once weekly, and a four-week dose-maintenance period through Week 26 without increases in study drug, active vitamin D, or calcium supplementation¹.

The primary endpoint at Week 26 is a composite responder measure requiring maintenance of normal albumin-adjusted serum calcium levels, independence from active vitamin D, reduction of calcium supplementation to 600 milligrams per day or less, and no increases in study drug dose during the four weeks before the Week 26 assessment¹. Additional endpoints will look at urinary calcium normalization along with physical function and symptom measures tied to hypocalcemia, as well as bone mineral metabolism, kidney health, bone biomarkers, patient-reported outcomes and long-term safety¹.

The company said the design draws on earlier findings from its Phase 2 Avail study and its extension, which it described as consistent with restored PTH activity across several measures including calcium and bone metabolism and kidney function, based on results consistent with restoration of systemic PTH activity, including normalization of serum calcium, reduction of urinary calcium excretion, restoration of bone metabolism and increase of eGFR¹. MBX noted that canvuparatide has received Orphan Drug Designation from the FDA and Orphan Designation from the European Medicines Agency for hypoparathyroidism¹.