The plaintiff in this lawsuit, Biogen International GmbH’s (“Biogen”), is the owner of Tecfidera® (dimethyl fumarate) delayed release capsules, approved by FDA for the treatment of multiple sclerosis in 2013. Biogen Int'l GmbH v. Banner Life Scis. LLC, 956 F.3d 1351 (Fed. Cir. 2020). When ingested, dimethyl fumarate is metabolized to its active metabolite, methyl hydrogen fumarate. These two molecules have the following chemical structures:
As can be seen on the right hand side of the molecule, methyl hydrogen fumarate is the de-esterified version of dimethyl fumarate.
The defendant in this lawsuit, Banner Life Sciences, LLC (“Banner”), took advantage of the metabolic relationship between dimethyl fumarate and methyl hydrogen fumarate, and secured FDA’s approval for methyl hydrogen fumarate merely by showing that its product was bioequivalent to Tecfidera®, in terms of blood concentrations of methyl hydrogen fumarate. Because methyl hydrogen fumarate is the active metabolite of methyl hydrogen fumarate, FDA did not require Banner to conduct any clinical studies to prove that its product can treat multiple sclerosis.
Biogen owns U.S. Patent No. 7,619,001, which covers the use of dimethyl fumarate and methyl hydrogen fumarate to treat multiple sclerosis. Claim 1 recites:
1. A method of treating multiple sclerosis comprising administering [a] pharmaceutical preparation comprising
at least one excipient or at least one carrier or at least one combination thereof; and
dimethyl fumarate, methyl hydrogen fumarate, or a combination thereof.
The patent was originally scheduled to expire on April 1, 2018. However, because FDA had never previously approved dimethyl fumarate, the United States Patent Office extended the patent’s term by 811 days, to June 20, 2020, after Biogen secured FDA approval.
As readers of this blog know, the Patent Office grants patent term extensions (“PTEs”) to patent owners under 35 U.S.C. 156 to compensate them for the delay they suffer securing regulatory approval for their drugs. However, under 35 U.S.C. 156, the Patent Office only grants PTE’s for new “drug products,” commonly referred to as new chemical entities (“NCEs”).
The question on this appeal was whether Biogen’s PTE covered Banner’s methyl hydrogen fumarate, or whether the PTE was limited to the methyl ester of methyl hydrogen fumarate. The Federal Circuit had little problem concluding that the PTE did not extend to methyl hydrogen fumarate, based on the definition of “drug product” in section 156(f)(2)(A):
(2)The term “drug product” means the active ingredient of—
(A)a new drug, antibiotic drug, or human biological product (as those terms are used in the Federal Food, Drug, and Cosmetic Act and the Public Health Service Act), …
including any salt or ester of the active ingredient, as a single entity or in combination with another active ingredient.
As stated by the Federal Circuit:
MMF [methyl hydrogen fumarate] is not the approved product, nor is it specified as the active ingredient on the Tecfidera® label. Esters are included in the statutory definition of what can be extended, but MMF is the de-esterified form of DMF [dimethyl fumarate], not an ester of DMF. Thus, it is not the same product under § 156(f) and does not fall within the scope of the '001 patent's term extension under § 156(b)(2).
In other words, a PTE can cover an esterified form of a drug, but the converse is not true. Biogen’s PTE did not cover methyl hydrogen fumarate because methyl hydrogen fumarate is the de-esterified version of the approved drug product.
