Shares of Amgen (AMGN) - Get Report  were rising nearly 5% Monday after the drugmaker won a patent case against rival Novartis  (NVS) - Get Report over its highly anticipated rheumatoid arthritis treatment Enbrel.

A U.S. District Court judge ruled in favor of Amgen over the validity of two patents governing Enbrel. Amgen's Enbrel patents likely will be protected until 2029. 

"We are pleased with (Friday's) decision recognizing the validity of these patents. Protecting intellectual property is critical to incentivize innovation and the large investments in research and development that are required to bring new medicines to patients and fully develop their therapeutic potential for patients," said CEO Robert A. Bradway.

Novartis said it would appeal the ruling to the U.S. Court of Appeals for the Federal Circuit. 

Enbrel has been on the market since 1998 after being developed by Immunex, which Amgen acquired in 2002. 

U.S. regulators have encouraged drug companies to make biosimilar drugs in recent years as a way to bring down rising drug prices. However, big drug companies have resorted to litigation in order to extend patent protections. 

Enbrel does have biosimilar competition in Europe. 

Amgen rose 5.64% to $207.31 in trading Monday. Novartis also was higher, up 0.7% to $91.46.

Amgen is a holding in Jim Cramer's Action Alerts PLUS charitable trust