Ultragenyx plummets after bone disease drug fails late-stage trials

Ultragenyx Pharmaceutical

29/12/2025 14:17

** Shares of Ultragenyx Pharmaceutical RARE.O plunge 42.5% to $19 premarket

** RARE says its experimental drug for a type of genetic bone disease did not meet the main goal in late-stage studies

** The drug, setrusumab, was being developed for people with osteogenesis imperfecta, a rare genetic disorder that causes brittle bones

** While the studies did not achieve statistical significance on fracture reduction, both showed meaningful improvements in bone mineral density, a key indicator of bone strength - RARE

** As of last close, stock was down 18.7% YTD

 (Reporting by Siddhi Mahatole)

 ((siddhi.mahatole@thomsonreuters.com))