Eisai wins key lenvatinib patent case in U.S.

Eisai Co., Ltd. (TSE:4523) announced a favorable decision in its U.S. patent infringement lawsuit against Shilpa Medicare Limited on May 28, 2025, protecting its lenvatinib (Lenvima) patent (U.S. Patent No. 11,186,547). The U.S. District Court for the District of New Jersey ruled in Eisai's favor, preventing Shilpa from obtaining FDA approval to sell a generic version of lenvatinib mesylate in the U.S. until February 2036, when the ‘547 patent and related exclusivity expires. This patent covers the highly pure lenvatinib mesylate found in Lenvima.