Fed Circ injects new life into Mylan dispute

Appeals court faults lower court’s claim construction and its reliance on intrinsic evidence alone | Court emphasises that extrinsic evidence is needed in litigation over heart disease drug.

Generic drug maker Mylan, now a part of Viatris, has persuaded a trio of judges at the US Court of Appeals for the Federal Cir cuit to throw out a claim construction delivered by a lower court in a dispute over a heart disease treatment.

The litigation centred on epoprostenol, a naturally occurring substance that is useful for treating cardiovascular diseases.

At the heart of the appeal was the meaning of ‘a pH of 13 or higher’, and more specifically, the understanding of what the significant digits are for ‘a pH of 13’.

In a precedential decision handed down yesterday, November 6, the Federal Circuit held that the US District Court for the Northern District of West Virginia had erred by not addressing all of the evidence available.

“Because this is a case where the district court must address the extrinsic evidence to understand how a person of ordinary skill in the art would understand the claim language, we vacate the district court’s claim construction order with respect to the term ‘a pH of 13 or higher’ and the judgment of infringement, and remand for the district court to consider the extrinsic evidence and its impact on claim construction,” said the court.

Mylan’s epoprostenol sodium injection

The lawsuit emerged when Actelion decided to sue over the allied infringement of its patents, US NUMBERS 8,318,802 and 8,598,227—both directed to improved epoprostenol formulations.

Actelion sells its epoprostenol product, an epoprostenol sodium for injection, under the brand name Veletri. The ’802 and ’227 patents are listed in the FDA’s publication ‘Approved Drug Products with Therapeutic Equivalence Evaluations’, commonly known as the Orange Book, as covering Veletri.

Mylan sought approval to manufacture and sell a generic epoprostenol sodium for injection by filing an Abbreviated New Drug Application (ANDA) with the US Food and Drug Administration.

Its ANDA argued that the ’802 and ’227 patents’ claims were invalid or would not be infringed by the ANDA product.

During proceedings, the parties disputed the meaning of the claim term ‘a pH of 13 or higher’. While both proposed the plain and ordinary meaning of the term, they disagreed on what that means.

Actelion argued that ‘a pH of 13’ in the context of the asserted claims is “a value of acidity that is given as an order of magnitude that is subject to rounding”.

More specifically, Actelion’s proposal would allow a pH of 12.5, which rounds to 13, to read on the claim limitation of “a pH of 13 or higher.”

By contrast, Mylan argued that the proper construction cannot cover any pH values less than 13.

Fed Circ: District court failed to scrutinise textbooks

Actelion attacked Mylan’s construction as, among other things, “chang[ing] the number of significant digits” and conflicting with the plain language of the claim.

It explained that: “To describe a specific pH value, and not an order of magnitude, there would need to be a significant figure to the right of the decimal point or clear context to the contrary.”

Following its acceptance of this claim construction, the district court ruled in favour of Actelion in June 2022.

The court explained that the claims “consistently expressed ‘a pH of 13’ with two significant figures” and that the “claim language provides no basis for inferring any higher level of precision”.

It reasoned that: “under its conventional significant figure meaning, the term a ‘pH of 13’ would ordinarily encompass those values that round up or down to 13, 12.5 to 13.4.6”.

Turning to the specification, the court concluded that “there is nothing to indicate that Actelion intended to import any higher degree of precision to ‘a pH of 13’ as it is articulated in the claims at issue.”

Similarly, the court was “unpersuaded that the prosecution history requires it to read an increased degree of precision into the claim language”.

The Federal Circuit, however, disagreed, finding that the district court adopted Actelion’s proposed construction based on an intrinsic record alone.

The lower court, it added, had failed to adequately scrutinise textbooks in order to fully determine an answer for how a person of ordinary skill in the art would view the significant digits for a pH value.

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