Arrowhead files lawsuit against Ionis over plozasiran patent dispute

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Arrowhead Pharmaceuticals Files Complaint for Declaratory Judgment Against Ionis Pharmaceuticals

September 11, 2025 7:30 AM EDT

PASADENA, Calif.--(BUSINESS WIRE)-- Arrowhead Pharmaceuticals, Inc. (NASDAQ: ARWR) today announced that yesterday it filed a Complaint for Declaratory Judgment in the United States District Court for the District of Delaware against Ionis Pharmaceuticals, Inc., to declare that Ioniss United States Patent No. 9,593,333 (the 333 patent) is invalid and not infringed by Arrowheads planned commercialization of investigational plozasiran, which is under FDA review. Arrowhead intends to vigorously pursue its claims in this litigation.

Ionis has threatened legal action against Arrowhead concerning its plozasiran product, including allegations of infringement of the 333 patent. Arrowhead believes... More