On November 30, 2021, the Federal Circuit affirmed the Northern District of West Virginia’s invalidity finding as to a method-of-treatment patent, based on a lack of written description.

Plaintiffs Biogen International GmbH and Biogen MA Inc. alleged Mylan Pharmaceuticals Inc. infringed several patents listed in the Orange Book for Tecfidera®, a dimethyl fumarate capsule indicated for the treatment of certain forms of multiple sclerosis. Among the asserted patents was U.S. Patent No. 8,399,514, which claims a method of treating MS with DMF and which was the sole patent addressed in the opinion.

The Specification Insufficiently Called Out the Claimed Dosage Amount

The representative claim of the ’514 patent recites a method of treating MS by administration of 480 mg/day of DMF. Mylan challenged that the 2007-filed specification did not support the issued claims, which were amended in 2011 to include the 480 mg/day dosage amount limitation. The Federal Circuit noted that the specification discloses a “broad array of nearly three dozen neurological disorders,” including MS, and assumed without deciding that the method of treating MS with DMF was adequately disclosed. The core issue then was whether the specification adequately disclosed the 480 mg/day dosage amount.

The Federal Circuit affirmed the district court’s finding that the specification lacked guidance for a 480 mg/day dose amount. The Court noted that the specification listed the 480 mg/day dosage amount only once, “at the end of one range among a series of ranges, including DMF concentrations of 100–1,000, 200–800, 240–720, and 480–720 mg/day.” Also noteworthy was “the specification’s focus on basic research,” with relatively less focus on methods of treatment. In contrast to the claimed 480 mg/day dosage amount, the specification provided independent references to a 720 mg/day dosage amount, which was “known to be effective as of the February 2007 priority date.”

Witness Admissions Informed the Specification’s Disclosures (or Lack Thereof)

The Court noted that the claims were amended in 2011 in view of the results of Phase III clinical trials demonstrating the efficacy of the 480 mg/day dosage amount. As part of those amendments, Biogen added a named inventor who had conceived of the 480 mg/day dosage amount. During trial, the inventor originally named as of the 2007 filing date testified that his research could not be “extrapolated to a clinical dose of DMF.” Instead, his work focused on drug discovery and small-molecule screening, which he admitted “had nothing to do with the clinical development of Tecfidera®.”

The Court also acknowledged that Mylan had impeached Biogen’s expert’s credibility. During the trial, Mylan pitted Biogen’s expert’s testimony regarding the understanding of a person of ordinary skill in the art of the 480 mg/day dosage amount from the specification, against his testimony during then-concluded IPR proceedings that a person of ordinary skill in the art would not have had a reasonable expectation of success of a 480 mg/day dosage amount. 

In view of these considerations, the Federal Circuit found no clear error in the district court’s determination of invalidity based on a lack of written description.

Best Practices: The Need for Effective Case Strategy

Biogen reaffirms written description as a potent invalidity defense, particularly in the context of method-of-treatment claims that rely on a disclosure focused on drug discovery. It also highlights the necessity of a holistic litigation strategy developed at the outset of the case. The fact that the district court, and in turn the Federal Circuit, cited inventor testimony, as well as the impact of post-filing clinical data, underscores that, even though the written description requirement is an objective evaluation based on the disclosure of the patent, witness admissions can strengthen a written description invalidity defense. 

Consequently, Mylan’s triangulation of Biogen’s expert testimony between the IPR proceedings and the district court litigation proved effective. Litigants would be wise to develop case strategy early on, keeping this in mind, in order to ensure that their arsenal contains what could be a valuable invalidity basis.