Azurity Pharms., Inc. v. Bionpharma Inc.

Epaned® (enalapril maleate)

Jan. 6, 2023

GENERICally Speaking

Case Name: Azurity Pharms., Inc. v. Bionpharma Inc., No. 21-cv-1455, 2023 WL 122292 (D. Del. Jan. 6, 2023) (Goldberg, J.)

Drug Products and Patent(s)-in-Suit: Epaned® (enalapril maleate); U.S. Patents Nos. 11,040,023 (“the ’023 patent”) and 11,141,405 (“the ’405 patents”)

Nature of the Case and Issue(s) Presented: In May 2018, Azurity sued Bionpharma alleging that Bionpharma’s proposed ANDA seeking to market generic enalapril would infringe Azurity’s U.S. Patents Nos. 9,669,008, 9,808,442, 10,039,745, and 10,154,987 (“the First Wave patents”). On April 27, 2021, Judge Stark entered judgment in favor of Bionpharma, finding that the ANDA did not infringe because, among other reasons, the ANDA product did not contain the buffer that the First Wave patent claims require. Azurity filed another lawsuit involving U.S. Patents Nos. 10,772,868, 10,786,482, and 10,918,621 (“the Second Wave patents”). After judgment in the first litigation became final on appeal, Azurity stipulated to dismissal of the second lawsuit.

This lawsuit involves the ’023 and ’405 patents. While their claims have some elements in common with the First and Second Wave patents, they differ with respect to whether the claimed liquids must contain buffers. Bionpharma moved for judgment on the pleadings, asserting that the judgment of non-infringement in the First Wave and subsequent stipulation of dismissal in the Second Wave are preclusive of Azurity's infringement claims in this litigation. The court denied Bionpharma’s motion.

Why Azurity Prevailed: The parties disagreed on the applicable test for determining whether two patent infringement claims are the “same cause of action” for purposes of claim preclusion. The court agreed with Azurity that the applicable test is whether “the scope of the asserted patent claims in the two suits is essentially the same.” Azurity argued that because each claim of the First and Second Wave patents required a buffer, and each claim of this litigation does not require a buffer, the claims of this litigation cover different scope. On the other hand, Bionpharma argued that the test from the law of “obviousness-type-double-patenting”—if the second claim would have been obvious to a skilled artisan with knowledge of the first claim—applied.

The parties’ divergent positions stem from the following sentence in the Federal Circuit’s SimpleAir decision: “In applying [the claim preclusion] standard to the particular context here, we conclude that claims which are patentably indistinct are essentially the same.” The term “patentably indistinct” is also used in the doctrine of obviousness-type double patenting. But the court found that the Federal Circuit interpreted SimpleAir differently than how Bionpharma advocated by repeatedly relying on the “essentially the same” Second, other statements in SimpleAir show that the test for claim preclusion differs from the test for obviousness-type double patenting. Finally, even if SimpleAir impliedly referenced the test for obviousness-type double patenting, that reference was unnecessary to the outcome and therefore dictum.

Applying the “essentially the same” test, the court found that the claim scope in the current litigation is not the same as in the First and Second Wave patents. “Eliminating the buffer limitation allows the claims to encompass enalapril liquids that do not contain buffers. That distinction is material because it impacts two of the three grounds on which Judge Stark found non-infringement in the First Wave.” The lack of a buffer limitation in the currently asserted claims was also significant because it underlies Bionpharma’s defense in this case that the patents’ written specification does not adequately describe liquids without buffers.

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