Two late‑stage clinical failures in brittle‑bone disease sent shockwaves through specialty biotech this week. Ultragenyx Pharmaceutical and Mereo Biopharma reported that Phase III trials of setrusumab (Orbit and Cosmic programs) missed their primary endpoints; both companies are now reassessing data and next steps. Market reaction was immediate, with Mereo and Ultragenyx shares plunging on the open as investors priced in program termination risk and balance‑sheet stress. The headlines stem from company trial announcements and reporting by industry outlets that tracked endpoint misses and subsequent stock moves. Both programs had been positioned as potential disease‑modifying options in osteogenesis imperfecta and related bone disorders. Developers and investors will be watching subgroup and secondary‑endpoint readouts to determine whether any salvage strategies exist, though near‑term capital and licensing options are likely constrained. Background: setrusumab is a monoclonal antibody targeting a bone‑modulating pathway; Phase III failures on primary endpoints typically force portfolio pruning or corporate restructuring. Analysts will model impairment charges and potential asset sales as the firms decide on next steps.