On March 16, 2022, the Court of Appeals for the Federal Circuit denied Biogen International GmbH and Biogen MA, Inc.’s (“Biogen”) combined petition for panel rehearing and rehearing en banc in Biogen International GmbH v. Mylan Pharmaceuticals Inc.¹ At issue was Biogen’s U.S. Patent No. 8,399,514 (the ’514 patent), which claimed methods for treating multiple sclerosis.  Mylan Pharmaceuticals Inc. (“Mylan”) contended that certain claims of the ’514 patent were invalid for lack of written description support in the specification.² The district court agreed with Mylan and in 2020 invalidated the claims of the ’514 patent that had been asserted by Biogen.³ The Federal Circuit subsequently affirmed the district court,⁴ a decision previously written about by our firm.⁵

The Federal Circuit recently denied en banc review.  In dissent from the court’s decision, however, Judge Lourie (joined by Judges Moore and Newman) argued that the court “lost an opportunity to provide clarity for future litigants by reaffirming the proper boundaries of the written description requirement in 35 U.S.C. § 112.”⁶ This dissent, coupled with the dissent from Judge O’Malley from the original Federal Circuit panel, will serve as solid support for a likely petition to the U.S. Supreme Court by Biogen seeking review of the appellate court decision and clarity on written description requirements for method of treatment claims involving dosing regimens.⁷

The ’514 patent is titled “Treatment for Multiple Sclerosis” and had been listed in the FDA’s Orange Book against Biogen’s approved drug product, Tecfidera^®, which is indicated for the treatment of relapsing forms of multiple sclerosis (MS). Representative claim 1 of the ’514 patent is set forth below:

A method of treating a subject in need of treatment for multiple sclerosis comprising orally administering to the subject in need thereof a pharmaceutical composition consisting essentially of (a) a therapeutically effective amount of dimethyl fumarate, monomethyl fumarate, or a combination thereof, and (b) one or more pharmaceutically acceptable excipients, wherein the therapeutically effective amount of dimethyl fumarate, monomethyl fumarate, or a combination thereof is about 480 mg per day.⁸

The dissent began its analysis by explicitly identifying key disclosures in the patent specification that support claim 1, noting that “the hallmark of written description is disclosure.”⁹ The key disclosures included

• an embodiment called “method 4” that discloses methods of treating neurological diseases, including MS, using dimethyl fumarate (DMF) and/or monomethyl fumarate (MMF);
• a statement that the patent is directed to compounds for the treatment of neurological diseases including demyelinating neurological diseases such as MS, along with a description of the pathology, symptoms, and treatment methods for MS;
• an effective dose of DMF or MMF of about 480 mg to about 720 mg per day, administered orally; and
• the title of the patent, “Treatment for Multiple Sclerosis.”¹⁰

In comparing these specification disclosures to representative claim 1, the dissent concluded that “claim 1 is directed to a method of treating a particular disease (multiple sclerosis) by administering particular compounds (DMF or MMF) at a particular dose (480 mg per day). And that is precisely what the specification discloses…”¹¹ Accordingly, the dissent determined that Biogen’s specification provided sufficient written description under 35 U.S.C. § 112.

Finding that the panel majority and the district court erred by analyzing factual and legal considerations that are not appropriate parts of a written description analysis, the dissent identified “four individual points of error” that an en banc court should have corrected.¹² First, the panel majority and district court were overly focused on unclaimed disclosures in the specification.¹³ Second, they imposed a burden on the patentee to demonstrate that the specification proves efficacy.¹⁴ Third, they considered legal factors that are part of other patentability requirements.¹⁵ And fourth, they were unduly swayed by irrelevant extrinsic evidence.¹⁶

A. Undue Emphasis on Unclaimed Disclosures in Specification

The dissent took issue with the panel majority and the district court’s comparisons between the amount of disclosure of claimed versus unclaimed subject matter in the specification. The dissent disagreed with the panel majority’s notion that a large ratio of unclaimed subject matter to claimed subject matter should be relevant to a written description analysis.¹⁷ For example, the panel majority focused on the fact that the specification disclosed nearly three dozen neurological disorders, in addition to MS, and that the effective dose of 480 mg per day is disclosed only a single time in the entire specification amongst a “series of ranges.”¹⁸

The dissent challenged the district court’s focus on unclaimed subject matter on the basis of Federal Circuit precedent supposedly requiring “blaze marks” in a specification that point a person of ordinary skill in the art (POSA) to the claimed species within a genus disclosure.¹⁹ Noting that “blaze mark analysis” originated in a case in which a specification “failed to disclose a claimed species within a disclosed genus,”²⁰ the dissent stated that blaze marks are not required where the specification expressly discloses the claimed species,²¹ as is the case here. Both the disease state “MS” and the effective dose “480 mg” are claim limitations that are expressly recited species within the specification.²²

The dissent therefore disagreed with the panel majority’s focus on unclaimed specification disclosures, and raised the concern that the panel majority’s opinion may suggest that a patentee must disclose claimed subject matter more than once in a specification, and/or that a court may count and compare the number of times claimed versus unclaimed subject matter is disclosed in a specification as part of a written description inquiry.²³

B. Imposition of Requirement That Specification Proves Pharmaceutical Composition’s Efficacy

The second error discussed by the dissent was the panel majority’s imposition of a requirement that the patentee show that the specification demonstrates the efficacy of the claimed pharmaceutical composition.²⁴ The panel majority and the district court had agreed that the asserted claims of the ’514 patent failed the written description requirement because the specification does not teach a POSA that a 480 mg/day dose of DMF is therapeutically effective in the treatment of MS.²⁵

The dissent disagreed, noting that Federal Circuit precedent does not require a patent to prove that a claimed pharmaceutical compound actually achieves a particular result,²⁶ since what is required of obtaining a patent is distinguishable from what is required for obtaining government authorization to market a drug.²⁷ For the purposes of satisfying the written description requirement for that claim limitation, the dissent argued that it is enough for  the specification to note that 480 mg is a “therapeutically effective” dose.

C. Importation of Extraneous Considerations Into Written Description Analysis

The next error that the dissent raised was the panel majority’s consideration of “extraneous legal considerations” as part of the written description analysis, including considerations of operability of the claimed invention.²⁸ Under 35 U.S.C. § 112, two separate written description requirements are described, that is, a written description (i) of the invention, and (ii) of the manner and process of making and using the invention.²⁹

The dissent stated that, in raising questions as to whether the 480 mg per day is an effective dose for treating MS, the panel majority and the district court erroneously imported enablement and operability requirements under 35 U.S.C. § 112 and §101 into the written description analysis.³⁰ While enablement concerns whether a patentee has proven that an invention works, and operability concerns whether a claimed invention can operate to produce what the patentee claims it produces, written description concerns whether a skilled reader of a patent disclosure can recognize that the claims correspond to the disclosed information.³¹

Additionally, the dissent noted that the panel majority and the district court were too focused on inventorship questions concerning the inventors’ roles in developing the technology underlying the claims,³² commenting that “[t]o the extent… that there was an inventorship problem with the ’514 patent, that is a separate issue from written description under 35 U.S.C. § 112.”³³

Furthermore, the dissent raised issue with the district court’s importation of a “best mode” requirement into the written description analysis, in response to the district court’s focus on questions relating to whether the person of ordinary skill would have been drawn to a 720 mg dose of DMF and would have known which particular dose among those disclosed in Column 18 of the ’514 patent would have been most effective in treating MS.³⁴

D. Consideration of Extrinsic Evidence

The final error that the dissent raised was the panel majority and the district court’s consideration of extrinsic evidence, since a written description analysis should require only
“an objective inquiry into the four corners of the specification.”³⁵ The dissent acknowledged that consideration of extrinsic evidence may sometimes be acceptable for determining how a skilled artisan would understand what is disclosed in a specification.³⁶ But when a specification disclosure “plainly corresponds to” a claim limitation, extrinsic evidence should not be considered to cast doubt on the meaning of a specification disclosure.³⁷

In this case, the dissent believed that the district court inappropriately focused on whether Biogen’s clinical trials pre-dating the patent’s filing date would have demonstrated the efficacy of particular doses of DMF in the treatment of MS, as well as on other extrinsic evidence such as disclosures in later-filed Biogen applications and arguments that Biogen made in a Patent Trial and Appeal Board inter partes review proceeding.³⁸

On the basis of the above-described four “points of error,” the dissent concluded that the Federal Circuit permitted an “erroneous broadening of the written description inquiry.”³⁹ For now, from a litigation perspective, generic pharmaceutical companies and other patent challengers will undoubtedly turn to Biogen v. Mylan as a basis for additional arguments for invalidating patent claims on written description grounds. From a prosecution perspective, those drafting patent claims may view Biogen v. Mylan as heightening the standards for providing adequate written description disclosures in a patent specification. At the same time, the original and en banc dissents expose fissures among the circuit judges on the written description standard. These disagreements may serve as the basis for Supreme Court review, and, in the interim, create uncertainty for patent owners and practitioners.