** Shares of Acadia Pharmaceuticals ACAD.O rise 14% to $27 premarket

** Co says that Committee for Medicinal Products for Human Use of the European Medicines Agency has adopted a positive opinion following a re-examination procedure on its marketing application for daybu for the treatment of neurobehavioral symptoms of Rett syndrome, following its recent CHMP oral explanation

** Rett syndrome is a rare genetic neurological and developmental disorder that affects the way the brain develops

** RBC Capital Market says "CHMP cited that while the effect sizes were small, the totality of the data was clinically relevant, resulting in the positive outcome"

** Brokerage adds the concerns had also been raised during the U.S. FDA's review of the drug, which nevertheless approved it, but expectations for a reversal in Europe were low

** RBC says "today's surprise CHMP reversal should further increase the fundamental valuation floor" for ACAD

** Following the CHMP recommendation, the European Commission will review the opinion and is expected to issue a final decision in the coming months

** As of last close, stock down 11.2% YTD