Exelixis Sues MSN Labs, Adding Three Patents to Cabometyx Feud

Exelixis Inc. expanded its quest to block cheaper generic versions of Cabometyx proposed by MSN Laboratories Private Ltd., filing a federal lawsuit Wednesday alleging infringement of three patents for the blockbuster cancer drug, its cash cow, that expire in January 2030.

The complaint is Exelixis’ third against MSN, all filed in the U.S. District Court for the District of Delaware. The Alameda, Calif.-based company first sued in October 2019, asserting one Cabometyx patent. It again sued MSN in May 2020 over two other patents for the drug. Those cases were consolidated that July.

On Wednesday, Exelixis sent a letter ...