(Adds background on case)
Oct 24 (Reuters) - A U.S. federal appeals court on Wednesday upheld a ruling that Biogen Inc's patents on its blockbuster multiple sclerosis drug Tecfidera are valid, rejecting a challenge by Danish drugmaker Forward Pharma A/S.
The U.S. Court of Appeals for the Federal Circuit said it agreed with a March 2017 ruling by the Patent Trial and Appeal Board that freed Biogen from future royalty payments to Forward.
Forward said in a statement it was disappointed with the ruling and considering its options. Biogen did not immediately respond to a request for comment.
The companies had been locked in a dispute over patents for dimethyl fumarate, the key active ingredient in Tecfidera, the leading oral MS treatment. Tecfidera had sales of about $4.2 billion in 2017.
Biogen's Tecfidera exclusivity in the United States is secured through 2028 under the ruling.
In January 2017, Biogen took out an insurance policy against a potential defeat in the patent dispute, agreeing to pay Forward $1.25 billion to license the companys patents covering MS drugs and gain a share of Forwards intellectual property.
The 2017 agreement would have allowed Forward to receive additional royalty payments if it had won the Federal Circuit appeal. (Reporting by Jan Wolfe Editing by Chizu Nomiyama and Paul Simao)