MBX Biosciences is advancing its hypoparathyroidism drug after 63% of patients achieved the primary endpoint of a Phase II trial.
The clinical-stage biopharma saw its stocks jump 100%. The share price increased from a 19 September close of $10.00 to a 22 September close of $20.00. This was after MBX announced that once-weekly canvuparatide achieved the trial’s primary endpoint.
In the Phase II Avail trial (NCT06465108), 63% of canvuparatide-treated patients met the prespecified primary composite endpoint. In this, patients maintained albumin-adjusted serum calcium in the normal range (8.2mg/dL–10.6mg/dL), and independence from conventional therapy, active vitamin D, and over 600mg/day of calcium supplements, with zero use of PRN rescue therapy after 12 weeks. In comparison, 31% of placebo-treated patients achieved this outcome.
The study drug also showed positive results in the six-month open-label extension (OLE) trial (NCT06531941). In this period, 79% of patients on once-weekly canvuparatide achieved responder status at six months. This included patients initially assigned to a placebo.
Responders were defined as patients who maintained serum calcium levels in the normal range and independence from conventional therapy (active vitamin D and more than 600mg/day of calcium supplements).
All 64 patients completed the 12-week study, and 94% of patients elected to enrol in the OLE.
All doses of canvuparatide were generally well-tolerated with no discontinuations related to the drug, with all treatment-emergent adverse events (AEs) being mild or moderate. Injection site reactions occurred in 19% of the pooled treatment group versus 13% in the placebo cohort.
Dr Mishaela Rubin, Professor of Medicine at Columbia University Vagelos College of Physicians and Surgeons and an investigator in the Avail clinical trial, said: “Hypoparathyroidism poses a substantial burden to patients, who often face complex treatment regimens and unpredictable swings in calcium levels that can lead to serious complications.
"The 12-week and six-month data provide promising early evidence that this investigational therapy may offer a potential option for long-term management, pending further study.”
Based on the data, MBX is preparing to initiate a Phase III clinical trial of once-weekly canvuparatide in 2026.
The drug could be a key revenue stream for MBX in the future. GlobalData predicts that canvuparatide will generate $603m in sales in 2031.
GlobalData is the parent company of Clinical Trials Arena.
HypoPARAthyroidism Association executive director Patty Keating said: “We are thrilled with these trial results. For so many in our community, life with hypoparathyroidism means living with constant symptoms and the limitations of daily supplements. A once-weekly treatment option that maintains stable calcium control while reducing the day-to-day burden would be a major step forward.”
Hypoparathyroidism landscape remains baron
Hypoparathyroidism is a rare endocrine disease caused by a deficiency of PTH. Symptoms include impaired regulation of calcium and phosphate levels in the blood.
This dysregulation of the physiological action of PTH can lead to clinical manifestations, including a negative impact on the kidney and bone. It is one of the largest known rare diseases and affects more than 200,000 people, mostly female, in the US and the European Union (EU).
The clinical space for hypoparathyroidism has been limited, with the standard treatment typically involving oral calcium and vitamin D supplementation. On 12 August 2024, Ascendis Pharma announced that the US Food and Drug Administration (FDA) approved Yorvipath (palopegteriparatide) as the first dedicated treatment for adults with hypoparathyroidism.
GlobalData predicts that Yorvipath will benefit from its first-to-market advantage and generate $2.36bn of sales in 2030.
Earlier this year, AstraZeneca’s $1bn bet on a hypoparathyroidism drug eneboparatide, originally developed by Amolyt Pharma, met the primary endpoint in a Phase III trial. GlobalData predicts eneboparatide will likely bring in $489m in sales in 2031.
