United States: Obviousness And Written Description Take Down An Infringed Patent

Holdings

In Azurity Pharms., Inc. v. Alkem Labs. Ltd., 2023 U.S. Dist. LEXIS 22848 (D. Del. Feb. 10, 2023), the district court held that Alkem's ANDA infringes Azurity's asserted claims, but the claims are invalid due to lack of written description support and obviousness.

Background

Azurity's claims relate to enalpril formulations. The individual claimed ingredients were known prior in the art. Azurity based its patentability on combining those ingredients into a liquid that would be stable for 12 to 24 months. Id. at *2. Representative claim 4 of the '621 patent reads:

A stable oral liquid formulation, consisting essentially of:

According to Alkem, its ANDA product does not infringe because it includes an ingredient not recited and the claim is limited in scope by the partially closed transition term "consisting essentially of" to only those ingredients that do not "materially affect the basic and novel properties of the invention." Id. at *10. Alkem's ANDA includes "a 'pH adjuster' added to ensure that the pH of the mixture is within a target range." Id. at *2-3. The ANDA "states that pH adjusters—sodium hydroxide and hydrochloric acid—should be added in an amount 'q.s.' The term 'q.s.' means 'quantum satis' or 'the quantity that's necessary.' ... Thus, sodium hydroxide and hydrochloric acid will be added as necessary to Alkem's ANDA to achieve the target pH range." Id. at *7-8.

Azurity argued that pH adjusters are only optional in Alkem's ANDA. Also, "when a pH adjuster is added, it disappears by reacting with other ingredients in the mixture such that it is no longer present in the final liquid." Id. at *3.

District Court

The district court first addressed the "pH adjuster" present in Alkem's ANDA. The court agreed "with Alkem that the pH adjusters, to the extent they are present, "materially affect the basic and novel properties of the invention." Id. at *14. But adding pH adjusters to the mixture does not avoid the "consisting essentially of" limitation "because the pH adjusters are consumed and are no longer present once the solution is mixed." Id. Since the mixture ultimately contains only listed ingredients, the court found that Azurity showed by a preponderance of the evidence that the "consisting essentially of" limitation is met. Id. at *15.¹

The district court also found that Alkem's ANDA met the buffer limitation, crediting the testimony of Azurity's expert. Id. at *16-17.

Although the court found infringement, it held that the claims lacked written description support and were obvious.

All the recited ingredients were known in the prior art. It was also known that enalapril could be mixed with water to make a liquid dosage form. Id. at *35. The court found that Alkem proved by clear and convincing evidence that the asserted claims would have been obvious; one of ordinary skill in the art would have expected that enalapril could be stable for a year or more in water at refrigerated temperature and that enalapril in water would be most stable if combined with a buffer to keep the pH at "about 3." Id. at *36-37. "[T]he requirements of a manufactured oral liquid would provide a motivation to combine these known ingredients into a single product." Id. at *37. The court also found that one of ordinary skill in the art would have had a reasonable expectation of success. "[T]he prior art did confer a reasonable expectation that mixing enalapril with water and adjusting the pH to about 3 could result in a drug that was highly stable for a long period of time." Id. at *45-46. Objective evidence of non-obviousness was "only minimally probative" and did not outweigh the evidence of obviousness.

With respect to written description support, "Azurity's expert Dr. Little acknowledged that the specification does not contain 'a disclosure of a formulation that meets all of the asserted claim limitations' of any asserted claim." Id. at *67. "The specification contains stability data for the[] examples, none of which extends beyond 8 weeks of testing, and the specification does not state whether any of the example liquids would be stable for 12, 18, or 24 months." Id. at *68.

"[A]ll asserted claims lack written description because the specification describes a large variety of ways to combine ingredients but does not say which combinations that use paraben preservatives are stable. That is, if a POSA were to combine ingredients from the specification, they would not know whether they would have the claimed invention." Id. at *70-71. The court noted that written description was "especially acute" when a claim recites functional language, as in this case where the patent owner claimed enalapril liquids that are "stable." Id. at *70.

Though the specification listed "many buffers, sweeteners, preservatives, and pHs that can be combined," without some direction as to which combinations would meet the recited claim limitations, one of ordinary skill in the art is left without the guidance required for patentability. Id. at *72-73. Nor did the stability testing data or examples in the specification help. Id. at *74. "[A] description that merely renders the invention obvious does not satisfy the written description requirement[.]" Id. at *72 citing Ariad Pharms. v. Eli Lilly & Co., 598 F.3d 1336, 1351 (Fed. Cir. 2010).

Azurity filed an appeal on Feb. 28, 2023.

Take Aways

This case serves as a reminder that transitional terms must always be considered carefully. What may seem helpful to expedite prosecution may not be helpful for later infringement arguments.

In addition, if the final ingredients in a composition differ from the starting ingredients, careful drafting to be clear what would infringe may help to strengthen the claim for enforceability later.

Often the idea of too much "picking and choosing" arises in an anticipation context. See In re Arkley, 59 C.C.P.A. 804, 455 F.2d 586, 587 (1972) (explaining that a disclosure must "direct those skilled in the art to the [invention] without any need for picking, choosing, and combining various disclosures[.]") Too much piecing together may also mean the disclosure is insufficient for written description support. This opinion refers to Idenix Pharmaceuticals LLC v. Gilead Sciences Inc., 941 F.3d 1149 (Fed. Cir. 2019), which presented a very similar set of facts. The court in Idenix described their analysis as "'looking for blaze marks which single out particular trees' in a forest, rather than simply 'pointing to trees.'" Id. at 1164. In that case, the court found that the patent at issue was invalid for lack of written description because it failed "to provide sufficient blaze marks to direct a POSA to the specific subset of 2'-methyl-up nucleosides that are effective in treating HCV. ... The specification, however, provides no method of distinguishing effective from ineffective compounds[.]" Id. "In the absence of that guidance, the listed examples and formulas cannot provide adequate written description support for undisclosed nucleosides that also happens to treat HCV." Id. Particularly in cases reciting functional limitations, drafters should try to provide "blaze marks" so one of ordinary skill in the art knows what combinations will meet the claim limitations.

Footnote

1. For case law on claim construction of mixtures, see, e.g., Mars, Inc. v. H.J. Heinz Co., L.P., 377 F.3d 1369, 1374 (Fed. Cir. 2004): "[C]laims to a mixture ordinarily go to 'a composition that contains the specified ingredients at any time from the moment the ingredients are mixed together.'" See also, Exxon Chem. Patents, Inc. v. Lubrizol Corp., 64 F.3d 1553, 1558 (Fed. Cir. 1995), later vacated and remanded on other grounds: "[A]s properly interpreted, Exxon's claims are to a composition that contains the specified ingredients at any time from the moment at which the ingredients are mixed together."

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