To recap, the case arose over Mylan's attempt to get regulatory approval and come to market with a generic equivalent of Biogen's Tecfidera® (dimethyl/monomethyl fumarate) multiple sclerosis drug. Biogen asserted Orange Book-listed U.S. Patent Nos. 6,509,376; 7,320,999; 7,619,001; 7,803,840; 8,399,514; and 8,759,393, but the parties dismissed their causes of action on all patents except the '514 patent, where Biogen asserted claims 1-4, 6, 8-13, and 15-16; claim 1 is representative:

1. 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.

(Wherein the italicized limitation was the entirety of the basis for the District Court's decision and the Federal Circuit majority's affirmance.)

The District Court held that the asserted claims were invalid for failure to satisfy the written description requirement of 35 U.S.C. § 112(a). The grounds for the District Court's decision, and the bases for Mylan's arguments that were persuasive, stemmed from certain characteristics of the prosecution history, which Mylan used to create an impression that Biogen had obtained claims based on clinical trial results for an invention not adequately disclosed in the application as filed in its earliest priority document (without such priority the claims perhaps would have been obvious). Moreover, certain claim limitations (importantly, the effective dose) were recited only as part of a range and only once in the specification, which in the main was directed to methods for identifying compounds for treating neurological diseases and mentioned the specific disease treated by the claimed method, multiple sclerosis, only as one disease amongst many. The District Court summed up the basis for its opinion succinctly, stating "[i]n sum, Biogen has attempted to satisfy the written description requirement of § 112 by selectively plucking specific words from the specification that correspond to each element of the claimed invention."

The Federal Circuit affirmed, in an opinion by Judge Reyna joined by Judge Hughes, with Judge O'Malley dissenting. Biogen was hampered by its burden of showing clear error by the District Court as well as the apparent "equities" between their position and Mylan's. The majority considered Biogen to have ""cast[] a wide net for a myriad of neurological disorders, including neuro-degenerative diseases such as amyotrophic lateral sclerosis (ALS), Parkinson's disease, Alzheimer's disease, and Huntington's disease; demyelinating neurological diseases, such as various forms of MS and at least twenty-eight other disorders related to demyelination; polyneuritis; and mitochondrial disorders with demyelination" (something Judge O'Malley herself termed a "laundry list" form of disclosure). The relevant elements of the claim (the disease treated, the drug used, and the dose) were each recited once in the specification, according to the majority, and those citations were scattered in different portions of the specification.

Judge O'Malley's dissent was based on her appreciation of the majority misunderstanding the differences between therapeutic and clinical efficacy and the differences between what is required to obtain a patent and what is required for FDA approval of a drug. This error, she contended, led the majority to apply the Court's Nuvo Pharms. (Ireland) Designated Activity Co. v. Dr. Reddy's Lab'ys Inc., 923 F.3d 1368, 1377, 1381 (Fed. Cir. 2019), precedent, also in error according to the Judge. And the Judge stated that in her view the specification contained an adequate written description based on this reasoning:

The majority's decision affirming the district court partially rests on the fact that the '514 patent only mentions the claimed DMF480 dose once. . . . But the majority cites no case law (and I know of none) for the proposition that the written description requirement demands that a patentee recite a claim element repeatedly to pass written description muster. The majority does not, and cannot, deny that the claimed DMF480 dose is expressly disclosed. To the extent the majority's opinion may be read to establish a requirement that a claim element must be disclosed multiple times, I dissent from that holding as well.

Judge Lourie's dissent from the Court's decision not to rehear the case en banc cites four grounds of error by the District Court (and by not subtle implication the Federal Circuit Judges constituting the panel majority). The dissent begins by noting that a proper written description analysis rests on the Court's en banc decision in Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336 (Fed. Cir. 2010), but Judge Lourie sets out Federal Circuit precedent involving the variety of cases where an adequate written description was not found (many of them written by the Judge himself) and based, according to the dissent, on the CCPA case In re Ruschig, 379 F.2d 990, 995 (C.C.P.A. 1967), and (somewhat provocatively) on O'Reilly v. Morse, 56 U.S. 62, 113 (1853). This case, according to the dissent, is an "outlier" "at the farthest end of the spectrum" because "every claim limitation is expressly described in the disclosure." And the consequence is that the Court has "let a panel majority opinion stand that imports extraneous considerations into the written description analysis and blurs the boundaries between the written description requirement and the other statutory requirements for patentability. In doing so, the court has contributed to the muddying of the written description requirement."

The basis for an adequate written description is always what is disclosed, according to Judge Lourie, and here Example 4 was expressly directed to treating MS; accordingly, "from any perspective, including that of a person of ordinary skill in the art, the '514 patent describes the invention of a method for treating multiple sclerosis." What is recited in claim 1, the dissent asserts, is "precisely what the specification discloses—treatment of multiple sclerosis with a 480 mg per day dose of DMF or MMF." "Whatever shortcomings exist in this unfocused patent specification, failure of written description with respect to claim 1 is not one of them" according to Judge Lourie's dissenting opinion.

So why did the panel majority go so astray in the dissenting Judges' opinion? The dissent sets out the four grounds of error by the District Court and the panel majority that provide the basis for why the District Court's opinion should have been reversed by the panel. The first is the "undue emphasis that the panel majority and the district court placed on unclaimed disclosures in the specification," engaging in "irrelevant comparisons between the amount of disclosure of the claimed subject matter versus the unclaimed subject matter," reciting as examples the majority's focus on the number of other neurological diseases set forth in the specification and the frequency (once) with which the 480mg dose was set forth. Agreeing with Judge O'Malley's dissent, Judge Lourie faults the panel majority for relying on In re Ruschig for the use of "blazemarks" in performing a written description requirement, because they thereby neglected the important distinction that in Ruschig the specification did not disclose the claimed embodiment. Discussing the extent of disclosure in genus/species claims, Judge Lourie recited portions of the body of precedent developed by the Court for making sufficiency determinations (a "representative number of species falling within the scope of the genus or structural features common to members of the genus so that one of skill in the art can 'visualize or recognize' the members of the genus," citing Regents of the Univ. of Cal. v. Eli Lilly & Co., 119 F.3d 1559, 1568–69 (Fed. Cir. 1997). It is only when a claimed species is not expressly disclosed in the context of a disclosed genus that a blazemarks analysis is needed according to the dissenting Judges, something expressly set forth in Novozymes A/S v. DuPont Nutrition Biosciences APS, 723 F.3d 1336, 1349 (Fed. Cir. 2013): "'[b]laze marks' are not necessary where the claimed species is expressly described in the specification." That is not the case here, Judge Lourie asserts, where the disease to be treated, the drug used for the treatment, and the administered dose is expressly disclosed. In such cases, whatever else is disclosed in the specification does not support a finding of inadequate disclosure according to the dissent, citing Scriptpro, LLC v. Innovation Assocs., Inc., 762 F.3d 1355, 1359 (Fed. Cir. 2014), nor is the fact that there was only a single mention of the 480 mg dose contrary to a finding of an adequate written description ("once is enough" according to the dissent, citing Vanda Pharms. Inc. v. W.-Ward Pharms. Int'l Ltd., 887 F.3d 1117, 1137 (Fed. Cir. 2018). Summing up this ground of error, the dissent states:

The panel majority opinion implies that a patent fails the written description requirement of 35 U.S.C. § 112 when it contains too much disclosure beyond the claimed invention, which is incorrect. The opinion implies that a patentee must disclose the claimed subject matter more than once, which is also incorrect. And the opinion implies that a court may arbitrarily count the number of times the claimed subject matter is disclosed in the specification relative to the number of times unclaimed subject matter is disclosed, which is incorrect.

The second ground of error (again in agreement with Judge O'Malley) is that Federal Circuit precedent does not require a patentee to show that "the specification proves the efficacy of the claimed pharmaceutical composition," citing Nuvo Pharms. (Ir.) Designated Activity Co.; In re Brana, 51 F.3d 1560, 1567 (Fed. Cir. 1995) (that the requirements for patenting and the requirements for drug marketing approval were different); and Scott v. Finney, 34 F.3d 1058, 1063 (Fed. Cir. 1994). Merely stating the claimed dose is enough, according to Judge Lourie because it "leaves nothing for the skilled artisan to deduce; it expressly states that 480 mg per day is an effective amount."

The third error made by the District Court and panel majority was importing "extraneous legal considerations into the written description analysis" contrary to Ariad. For example, the dissent notes that while operability can be raised with regard to enablement, Ariad stands for the distinction between the written description and the enablement requirements of the statute. "By focusing on whether the patentee proved that 480 mg per day is an effective amount to treat multiple sclerosis—as distinct from whether the '514 patent specification discloses that 480 mg per day is an effective amount to treat multiple sclerosis—the panel majority and the district court erroneously imported operability considerations into the written description analysis" (emphasis in dissenting opinion). Even further the dissent criticizes the District Court and the panel majority for considering inventorship issues, which is also separate from a proper written description requirement analysis. The dissent also appreciates the majority to have introduced a best mode issue, in reference to whether the skilled artisan would have been "drawn to" the 720 mg dose (emphasis in dissenting opinion). Once again, the dissent asserts that "[b]y incorporating extraneous legal standards into the analysis, the panel majority opinion creates confusion for future patent applicants and litigants regarding what is required to meet the written description requirement of 35 U.S.C. § 112."

The fourth point of error in the dissenting Judges' view was consideration of extrinsic evidence by the District Court and the panel majority. Under Ariad, "[t]he test for written description 'requires an objective inquiry into the four corners of the specification.'" While considerations outside the four corners can be relevant (regarding, for example, the understanding of one or ordinary skill in the art), such considerations need to be limited to "an objective inquiry into what is meant by the disclosure in the patent specification" according to the dissent. Where, as here, "the disclosure in a patent's specification plainly corresponds to what is claimed, extrinsic evidence should not be used to cast doubt on the meaning of what is disclosed."

The dissent concludes by stating that the best reason for the en banc Court to hear this case is that the panel majority had "affirmed a district court's erroneous broadening of the written description inquiry" and by denying rehearing the case 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."

It would be good to remember that satisfaction of the written description requirement is a question of fact, and such questions do not easily lend themselves to readily applied, rigid rules. Thus the strength of Judge O'Malley's dissent and the dissenting Judges here is directed at the proper application of the law to the question before the Court, which if in the unlikely event it ever arises again would be persuasive but is not likely to be binding precisely because such future facts are unlikely to be entirely on all fours with the question before the Court here. More significant, perhaps, is that the Court has trended towards a more stringent application of written description questions during Judge Prost's tenure as Chief Judge, and with the appointment of Judges Cunningham and Stark and Judge Moore taking the position of Chief Judge that may change, perhaps to a greater consistency with what was presumed to be settled Federal Circuit law.

Biogen Int'l GmbH v. Mylan Pharmaceuticals Inc. (Fed. Cir. 2022)
Panel: Chief Judge Moore and Circuit Judges Newman, Lourie, Dyk, Prost, O'Malley, Reyna, Taranto, Chen, and Hughes (Circuit Judge O'Malley retired on March 11, 2022, and participated only in the decision on the petition for panel rehearing)
Order per curiam; opinion dissenting from the denial of the petition for rehearing en banc by Circuit Judge Lourie, joined by Chief Judge Moore and Circuit Judge Newman