By Blake Brittain

Aug 14 (Reuters) - Amgen AMGN.O convinced a federal judge in Delaware on Thursday to invalidate two patents owned by Lindis Biotech, undercutting a $50.3 million jury verdict Lindis won last year in an infringement lawsuit over Amgen's leukemia drug Blincyto.

U.S. District Judge Gregory Williams said in a court order that the patents were unenforceable due to their inventor's "inequitable conduct" at the U.S. Patent and Trademark Office. Williams' opinion outlining his reasoning for the decision was filed under seal.

Attorneys and spokespeople for the companies did not immediately respond to requests for comment on the ruling.

Germany-based Lindis sued Amgen in 2022, alleging that Blincyto infringed patents related to reducing the side effects of using antibodies to stimulate the body's immune system to kill cancer cells.

Thousand Oaks, California-based Amgen earned $800 million from U.S. sales of Blincyto last year, according to a company report.

A Delaware jury determined in December that Amgen owed at least $50.3 million for infringing Lindis' patents. The jury also said that the infringement was willful, which could have led the court to increase the award up to three times the amount.

Amgen argued that the patents were invalid because their inventor submitted false information in his patent application. Williams held a separate bench trial in January on Amgen's defense.

The case is Lindis Biotech GmbH v. Amgen Inc, U.S. District Court for the District of Delaware, No. 1:22-cv-00035.

For Amgen: Michael Wise, Joseph Hamilton, Lara Dueppen, Courtney Prochnow and Alisha Burgin of Perkins Coie; Lisa Pensabene, Hassen Sayeed, Carolyn Wall, Luann Simmons and Sorin Zaharia of O'Melveny & Myers

For Lindis: James Taylor, Jessica Jones, Henry Platt, Robert Gill and Matthew Antonelli of Saul Ewing

Read more:

Amgen hit with $50.3 mln US verdict in cancer drug patent lawsuit

(Reporting by Blake Brittain in Washington)

((blake.brittain@tr.com; +1 (202) 938-5713))