Arrowhead climbs on early Alzheimer's drug trial data

** Shares of drugmaker Arrowhead Pharmaceuticals ARWR.O rise 6.7% to $62 premarket

** Co says its experimental Alzheimer's drug, ARO-MAPT, cut levels of disease-linked tau protein in spinal fluid by an average of 73% in healthy volunteers, with maximum reductions of 85%, in an early-to-mid-stage trial

** Abnormal buildups of tau protein are considered a key driver of Alzheimer's and other neurodegenerative brain disorders

** Protein reductions lasted for at least three months after the final dose, supporting the potential for quarterly dosing, co says

** Co is now testing the drug in early Alzheimer's patients, with data updates expected in 2027

** As of last close, stock down ~12% YTD