MBX Biosciences (MBX) said Monday that a mid-stage study of canvuparatide has met its primary endpoint in adult patients with chronic hypoparathyroidism, with 63% of treated patients reaching responder status at 12 weeks.

Data from the study's open-label extension showed that 79% of patients achieved responder status at six months, the company said.

Responders were defined as patients who maintained serum calcium levels within the normal range while remaining independence from conventional therapy, MBX said.

The company said the therapy was well tolerated, with no treatment-related serious adverse events, and preparations are underway for a late-stage trial next year.

Shares of MBX Biosciences were up 90% in recent Monday premarket activity.