Arrowhead Pharmaceuticals reported early trial data showing its brain-targeting RNA interference approach can lower tau levels after subcutaneous dosing in healthy volunteers. In the company’s ARO-MAPT study, the highest dose reduced tau by an average of 73% after 105 days, with results framed around safety and target engagement rather than clinical benefit. The program uses an RNAi platform intended to reach cells outside the liver and across the blood-brain barrier, targeting CNS-relevant gene expression implicated in Alzheimer’s progression. The update arrives as the Alzheimer’s field continues to differentiate next-wave tau-directed and non-amyloid approaches, while investors watch for evidence that target lowering translates into disease modification in later-stage trials.