Ionis Pharma up after US FDA approves rare brain disorder treatment

** Shares of Ionis Pharmaceuticals IONS.O rise 1.5% to $59 premarket

** U.S. FDA late on Thursday approved co's therapy to treat a rare disease that affects the brain

** Ionis' injectable drug zilganersen, branded Zanvastro, can be used to treat adults and pediatric patients with Alexander disease, a neurological disorder that damages brain cells and causes problems with movement, speech and swallowing

** In an early-to-late-stage study, patients who got a 50 mg dose of Zanvastro showed a statistically significant improvement in gait speed as assessed by a 10-meter walk test at 61 weeks

** Zanvastro will be available in the U.S. in the coming weeks - IONS

** As of last close, stock down 26.5% YTD