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Biogen v. Mylan – Therapeutic v. Clinical Efficacy – What is Required by the Written Description Requirement?

In Biogen v. Mylan, Appeal No. 2020-1933 (Fed. Cir., November 30, 2021), a divided panel of Judges O’Malley, Reyna and Hughes affirmed a district court’s ruling that Biogen’s U.S. Pat. No. 8,399,514 is invalid for failing to meet the written description requirement [WDR] of s. 112(a).  Judges Reyna and Hughes were the majority, while Judge O’Malley penned an 11-page dissent.

The claimed invention is a method of treating multiple sclerosis—MS—with dimethyl fumarate at a therapeutically effective amount of “about 480 mg/day”, referred to in the opinion as “DMF480.” The majority wrote that “the specification casts a wide net for a myriad of neurological disorders.” The specification also contained a paragraph giving a number of mg/day ranges, including “from about 480 mg to about 720 mg/per day.” “Therapeutically effective dose” is defined broadly, in three aspects: (a) prevention or delay of onset or amelioration of symptoms, (b) attainment of a biological outcome, such as reduction of neuronal death and (c) reduced inflammation of the cells of the CNS. In a Phase III clinical trial conducted after the effective filing date of the application, DMF480 was found to be effective.

While Mylan attempted to emphasize the failure of the specification to adequately link the use of DMF to treat MS, the majority seemed to agree with O’Malley that the many references to DMF and MS in the specification would convey to the POSA that the link was sufficient to meet the WD. However, the majority faulted the patent for only mentioning DMF480 once and then only as one anchor of a range. The majority found that the inventors “did not possess a therapeutically effective DMF 480 dose at the time of filing in 2007.” This is splitting a WDR hair, since it requires the specification to describe the specific dose recited in the claims. I can’t help thinking that Biogen’s strategy of isolating a specific clinically effective dose from an application that mainly was directed to new drug discovery methods was gaming the system, but Biogen was playing by the rules that we all know how to apply.

The patent had survived IPR and had been found to be non-obvious by the PTAB, at least partly because Biogen had convinced it that a person of ordinary skill in the art would find that the patent demonstrated unexpected results. As a result, the district court judge estopped Biogen from pointing out the distinction between clinical efficacy and therapeutic effects, presumably because Biogen was now attempting to argue that the art worker would go on to find the specification adequate to show possession of the invention.

But, as O’Malley points out, this improper estoppel caused the majority to conflate therapeutic efficacy with the results of a higher bar required to show efficacy via clinical trials:

“[I]t is clear on its face of the ‘514 patent that the claimed ‘therapeutically effective amount’ refers to DMF’s ability to mitigate MS symptoms vis-à-vis its modulation of Nrf2 expression; it has nothing to do with whether DMF480 outperforms the standard of care for MS (Rebif®) in a Phase III clinical trial.”

Finally, the district court had found that the patent did not contain enough “blaze marks” to lead the POSA to the claimed invention.  O’Malley spent some pages explaining why this informal doctrine is used to evaluate the species necessary to provide support for a generic claim, and not applicable to the “linking” issue discussed above.

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