Ultragenyx's Phase 3 Aspire trial of apazunersen misses its primary and key secondary endpoints in Angelman syndrome, sending shares down more than 40%.

The failure of what was once considered a potential blockbuster therapy represents a major setback in a tough-to-treat disease and is forcing Ultragenyx to closely examine its…

Ultragenyx's Phase 3 Aspire trial of apazunersen misses its primary and key secondary endpoints in Angelman syndrome, sending shares down more than 40%.