Forward Pharma A/S intends to appeal the U.S. Patent Trial and Appeal Board's decision to validate Biogen Inc.'s patent for the multiple sclerosis drug Tecfidera.

Biogen has already paid $1.25 billion to license the Danish drugmaker's treatment method for multiple sclerosis, using a 480-milligram daily dose of dimethyl fumarate.

But the two companies were in dispute over patent rights for dimethyl fumarate, the active ingredient in Tecfidera.

Under the board's ruling, Biogen will now not owe any future royalty payments to Forward Pharma, and its Tecfidera patents will remain in force until 2028.

If Forward Pharma is successful in its anticipated appeal and Biogen obtains an exclusive license to all intellectual property in the U.S. that is owned by Forward Pharma under a license agreement, a royalty of 10% would be payable by Biogen on net sales in the U.S. of applicable infringing products from Jan. 1, 2021, to Dec. 31, 2028, until the earlier of the expiration or invalidation of the patents owned by Forward Pharma in the U.S.