(Adds background on case)
By Jan Wolfe
Oct 12 (Reuters) - A U.S. appeals court on Friday upheld a ruling that canceled patents owned by Teva Pharmaceutical Industries Ltd on its blockbuster multiple sclerosis drug Copaxone.
The ruling was a victory for a group of generic drug companies, including Mylan NV and Novartis AG unit Sandoz, that challenged the validity of Teva's patents in order to sell generic versions.
Teva did not immediately respond to requests for comment.
The patents cover a 40-milligram injection of Copaxone that patients administer three times a week.
A Delaware judge in January 2017 canceled those Teva patents on the grounds that they described obvious concepts.
The U.S. Court of Appeals for the Federal Circuit said in Friday's decision that the lower court ruling was not clearly flawed.
At the time of the lower court ruling, Copaxone was Teva's best-selling drug, generating $4 billion in annual sales.
Mylan launched a generic version of Copaxone in 40-milligram formulations earlier this year, eroding Teva's market share.
Reporting by Jan Wolfe; Editing by Bernadette Baum