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Holy Pulmonary Hypertension, Batman: Method of Treatment Not Constrained by Safety and Efficacy

The US Court of Appeals for the Federal Circuit affirmed a district court’s holding that the asserted method of treatment patent was valid and infringed because safety and efficacy are not patent concerns. The Federal Circuit also affirmed the district court’s holding that certain claims of the product-by-process patent were invalid because the claimed product was in the prior art, regardless of the process by which it was made. United Therapeutics Corporation v. Liquidia Technologies, Inc., Case Nos. 22-2217; 23-1021 (Fed. Cir. July 24, 2023) (Lourie, Dyk, Stoll, JJ.)

United Therapeutics is the maker of Tyvaso®, a treprostinil formulation approved for treating pulmonary hypertension. United Therapeutics asserted two patents covering Tyvaso® against Liquidia’s § 505(b)(2) new drug application (NDA) on Yutrepia™. One patent was a method of treatment patent claiming to treat pulmonary hypertension by administering a “therapeutically effective” dose of a treprostinil formulation, and the other was a product-by-process patent claiming a treprostinil composition with lowered levels of impurities made by a specific salt formation process.

The district court found that United Therapeutics showed that a single administration of treprostinil improves a patient’s hemodynamics, establishing that administration of Liquidia’s Yutrepia, comprising treprostinil, would directly infringe the method of treatment claims. The district court also concluded that even though Yutrepia’s label did not provide hemodynamic data, the label’s instructions would inevitably lead to the administration of a therapeutically effective single event dose. The court thus concluded that Liquidia would induce infringement of the method of treatment claims.

The district court further found that the asserted claims were not invalid for lack of enablement or written description. The court reasoned that a skilled artisan would not need to engage in undue experimentation to practice the full scope of the claimed treatment of pulmonary hypertension, despite potential safety concerns in treating certain patients, since the claims did not require safety and efficacy. The court found that the claims were not invalid for lack of written description, finding that a skilled artisan would, based on the specification, understand that treprostinil would effectively vasodilate the pulmonary vasculature, improve hemodynamics and treat a patient’s elevated pulmonary blood pressure.

Liquidia appealed on five issues: claim construction of the term “treating pulmonary hypertension,” enablement, written description, induced infringement and infringement of the product by process claims. United Therapeutics cross-appealed on anticipation of the product by process claims and non-infringement of those claims.

First, regarding the construction of “treating pulmonary hypertension,” the Federal Circuit affirmed that the term encompassed all recognized groups of pulmonary hypertension but noted that the claim language “treating pulmonary hypertension” did not import any additional efficacy limitations or safety limitations, even those in a group that would not benefit from the treatment. The Court declined to read any safety or efficacy requirements into the claims, explaining that absent incorporation into the claims, the safety and efficacy of a claimed treatment are the purview of the US Food & Drug Administration (FDA), not patent law.

Regarding enablement and written description, Liquidia argued that the method [...]

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Product-by-Process Analysis Applies to Method of Treatment Claims

In a case relating to use of recombinant human interferon-β (IFN-β) proteins for the treatment of viral diseases, the US Court of Appeals for the Federal Circuit ruled that a “product-by-process” analysis applies even when the product-by-process limitation is nested within a method of treatment claim. Biogen MA Inc. v. EMD Serono, Inc., et al., Case No. 19-1133 (Fed. Cir. Sept. 28, 2020) (Linn, J.).

The claims at issue relate to a method of treating a viral condition, a viral disease, cancers or tumors by administration of a pharmaceutically effective amount of recombinant IFN-β. The claims contained a product-by-process limitation that partially defined the recombinant IFN-β in terms of the method or process by which it is made:

a recombinant polypeptide produced by a non-human host transformed by a recombinant DNA molecule comprising a DNA sequence selected from the group consisting of . . .

It was undisputed that native IFN-β proteins comprise sequences identical to those recited in the claims at issue, and that native IFN-β had been used in the prior art to treat viral conditions. At issue was whether the use of native IFN-β to treat viral conditions anticipated the use of recombinantly produced IFN-β for the claimed treatment.

When considering product-by-process claims, the Federal Circuit has long held that “an old product is not patentable even if it is made by a new process.” See, e.g., Amgen v. Hoffmann-La Roche (Fed. Cir. 2009). The district court granted Biogen’s judgment as a matter of law (JMOL) motion and reversed the jury verdict on anticipation, reasoning that the Amgen analysis did not apply here because the claims were directed to a method of treatment and not a product. Further, the “source limitations” (i.e., the limitations requiring that the IFN-β be produced using recombinant methods) overcame the shortcoming of the prior art. Namely, the unavailability of native IFN-β in sufficient quantity to facilitate practical treatment “lies at the heart of the benefit of this invention” and should be given “force and effect in the anticipation analysis.” Serono appealed.

The Federal Circuit reversed, explaining that the nesting of the product-by-process limitation within a method of treatment claim does not change the proper construction of the product-by-process limitation itself. The Federal Circuit reasoned that “an old method of administration of an old product made by a new process is not novel and cannot be patented.” Further, the Court found that the district court erred in considering the advantages of the recombinant process—the new capability of manufacturing sufficient quantities of IFN-β through recombinant technology—as a reason not to apply the product-by-process analysis. The proper anticipation analysis does not turn on the source of the claimed polypeptide, but on a comparison of the claimed recombinant polypeptide and the prior art native polypeptide.

In granting JMOL, the district court alternatively reasoned that under a product-by-process analysis, the native IFN-β could not anticipate recombinant IFN-β, because the prior art did not disclose that the native and recombinant IFN-β shared an identical three-dimensional structure or that [...]

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