Arrowhead tanks as its hep B treatment disappoints in Phase II

Arrowhead Research ($ARWR) watched its shares nose-dive after a peek at Phase II data on its in-development treatment for hepatitis B revealed that the RNAi therapy isn't measuring up to its preclinical promise. In an abstract released ahead of next month's American Association for the Study of Liver Diseases meeting, Arrowhead's ARC-520 led to slight reduction in viral levels in a Phase II study, failing to stack up to the company's earlier primate results despite management's August assertion that a look at blinded data suggested a "similar" effect. The news sent Arrowhead's stock price plunging nearly 50% on Wednesday morning. More