MBX Biosciences Posts 57% One-Year Response, 90% Retention And Plans Phase 3 Start
MBX•MBX Biosciences reported a 57% responder rate at one-year OLE with canvuparatide in chronic hypoparathyroidism, matching 63% response at 12 weeks and showing 90% patient retention. Treatment normalized serum calcium, reduced urine calcium excretion and improved eGFR with no new safety signals, backing a Phase 3 start in Q3 2026.
1. One-Year OLE Efficacy Results
At one year in the open-label extension, 57% of evaluable patients achieved the primary composite endpoint—maintaining normal albumin-adjusted serum calcium without conventional therapy—closely matching the 63% responder rate at 12 weeks. Patient retention remained high, with 90% of participants continuing through the full year.
2. Physiologic Effects and Biomarkers
Canvuparatide sustained serum calcium within the normal range and drove continued reductions in 24-hour urine calcium excretion. Bone turnover markers (CTx and P1NP) displayed expected patterns of PTH-driven remodeling, while mean eGFR improved over baseline at Week 12 and remained elevated at one year.
3. Safety and Tolerability
Once-weekly dosing was generally well tolerated over one year, with mostly mild to moderate adverse events and no new safety signals. Injection site reactions occurred in 10% of patients, and no treatment-related serious adverse events were reported.
4. Phase 3 Development Outlook
MBX remains on track to initiate its pivotal Phase 3 trial in Q3 2026, leveraging stable pharmacokinetics that support convenient once-weekly dosing. These data bolster the potential of canvuparatide as a best-in-class PTH replacement therapy for chronic hypoparathyroidism.
