Holding
In Azurity Pharms., Inc. v. Alkem Labs. Ltd., 2023 U.S. Dist. LEXIS 77839 (D. Del. May 4, 2023), the district court held that Azurity failed to show that Alkem's ANDA infringed the asserted claims.
Background
Plaintiff Azurity sued Alkem under the Hatch-Waxman Act for infringement of U.S. Patent No. 10,959,948 ("the '948 patent"). The '948 patent claims a composition and method of treatment for vancomycin oral liquid. Representative Claim 5 reads:
A non-sterile stable liquid formulation formulated for oral administration, consisting of:
(a) a buffering agent, wherein the buffering agent is selected from the group consisting of citric acid, sodium citrate, [and many other chemicals],
(b) water,
(c) a sweetener,
(d) a preservative, wherein the preservative is selected from the group consisting of sodium benzoate, parabens, benzoic acid, potassium sorbate, benzyl alcohol or salts thereof,
(e) vancomycin hydrochloride, and
(f)flavoring agent,
wherein the non-sterile stable liquid formulation is homogenous and stable for at least 1 week at ambient and refrigerated temperature and has a pH of 2.5-4.5.
Azurity alleged that the combination of two ingredients in Alkem's formulation, grape flavor and propylene glycol, met the "flavoring agent" limitation. That is, when grape flavor is mixed with propylene glycol in Alkem's ANDA product, the combination meets the "flavoring agent" limitation. Id at *36.
Azurity's expert testified that "the term 'flavoring agent' is used to mean 'a mixture of ingredients that imparts flavor to a formulation.'" Id. at *8. "Both parties' experts agreed that a single flavoring agent may contain multiple ingredients," including "non-flavorful" ingredients. Id.
Alkem argued that the presence of an unclaimed ingredient, propylene glycol, meant its formulation did not infringe. Id. at *4. Alkem's expert testified that "propylene glycol would generally not be considered for use as a flavor by itself because it has practically no taste." Id. at *9. Alkem's ANDA, however, "describes the whole of Grape Flavor 501417C, including its propylene glycol, as a 'flavoring agent.'" Id. at *13.
Alkem's ANDA also contains an additional 1 milligram per milliliter of propylene glycol described as a co-solvent. "[O]nce mixed, both propylene glycols interact equally with the grape-flavored chemicals in Grape Flavor 501417C." Id. at *14. The infringement dispute focuses on the "co-solvent" propylene glycol. Id. at *14.
Alkem also argued that Azurity disclaimed propylene glycol during prosecution of a parent application. Id. at *18. Azurity's original claim used the transition term "comprising," an open term allowing for a claim scope that includes unrecited ingredients. Id. at *21. When that claim was rejected, in order to distinguish the prior art reference, Azurity amended the claim to include a negative limitation: "wherein the liquid solution does not comprise a [sic] propylene glycol[.]" Id. at *22. After further prosecution, Azurity introduced claims using the transition term, "consisting of," and without the negative limitation. Azurity argued that the "consisting of" language "excluded both propylene glycol and polyethylene glycol and thus distinguished [the prior art reference]." Id. at *29. The examiner allowed the claims, noting that "[t]he instant claims exclude the presence of propylene glycol or polyethylene glycol in view of the consisting of language[.]" Id at *31.
In prosecuting a sibling application, Azurity stated that its arguments during prosecution of the parent application "did not disclaim propylene glycol ... and reserves the right to claim propylene glycol in the instant and future cases in this patent family." Id. at *34.
District Court
The district court noted that since the claim recited the transition term, "consisting of," the claim scope is limited to "'only what is expressly set forth in the claim' and 'excludes any element[,] step, or ingredient not specified in the claim.'" Id. at *11.
"[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.' Mars, Inc. v. H.J. Heinz Co., L.P., 377 F.3d 1369, 1374 (Fed. Cir. 2004)." Id. at *37.
The district court concluded that the prosecution history statements about the invention not including propylene glycol applied to limit the claims. The court further explained that
[t]he Examiner's statement shows there was a common understanding that Azurity's purpose in adding the "consisting of" language was to exclude propylene glycol. It is also evident that Azurity agreed with the Examiner's interpretation, because Azurity submitted the claims that would become the '948 patent shortly after the Examiner made the above statement—and, in doing so, repeated the "consisting of" language in its new claims. For these reasons, the above representations by Azurity were a "clear and unmistakable" disclaimer that its invention did not include propylene glycol.
Id. at *49. "Azurity's disclaimer of propylene glycol therefore applies to the "co-solvent" propylene glycol, irrespective of whether there might exist other, unspecified infringing flavoring agents that contain propylene glycol." Id. at *56.
Since Alkem's ANDA includes propylene glycol, the court found that it did not infringe. Id. at *54-55.
Take Aways
Be very careful with statements to secure patentability! "[T]he prosecution history can often inform the meaning of the claim language by demonstrating how the inventor understood the invention and whether the inventor limited the invention in the course of prosecution, making the claim scope narrower than it would otherwise be." Phillips v. AWH Corp., 415 F.3d 1303, 1317 (Fed. Cir. 2005) (en banc). Claims may not be construed one way in order to obtain their allowance and in a different way against accused infringers. See also, Pall Corp. v. PTI Technologies Inc., 259 F.3d 1383, 1392 (Fed. Cir 2001); Salazar v. Procter & Gamble Co., 414 F.3d 1342, 1344 (Fed. Cir. 2005); UCB, Inc. v. Yeda Research and Development Co., 837 F.3d 1256 (Fed. Cir. 2016). "Prosecution history is especially important when the invention involves a crowded art field, or when there is particular prior art that the applicant is trying to distinguish." Engel Indus. v. Lockformer Co., 96 F.3d 1398, 1405 (Fed. Cir. 1996). As the Federal Circuit noted in Hockerson-Halberstadt, Inc. v. Avia Group International, Inc., 222 F.3d 951 (Fed. Cir. 2000):
HHI's argument therefore reduces to a request for a mulligan that would erase from the prosecution history the inventor's disavowal of a particular aspect of a claim term's meaning. Such an argument is inimical to the public notice function provided by the prosecution history. The prosecution history constitutes a public record of the patentee's representations concerning the scope and meaning of the claims, and competitors are entitled to rely on those representations when ascertaining the degree of lawful conduct, such as designing around the claimed invention. [citations omitted] Were we to accept HHI's position, we would undercut the public's reliance on a statement that was in the public record and upon which reasonable competitors formed their business strategies. [citations omitted]
Id. at 957.
Exercising caution also applies during the prosecution of the entire patent family. The prosecution history of any parent or grandparent application may be considered as intrinsic evidence in the claim construction of the child application. "When multiple patents derive from the same initial application, the prosecution history regarding a claim limitation in any patent that has issued applies with equal force to subsequently issued patents that contain the same claim limitation." Elkay Mfg. Co. v. Ebco Mfg. Co., 192 F.3d 973, 980 (Fed. Cir. 1999). The court's reasoning is that it would be inapposite to allow a continuing application the benefit of the parent's priority filing date, but then consider the continuing application's prosecution history separately from that of the parent for claim construction purposes. See also, Biovail Corp. Int'l v. Andrx Pharms., Inc., 239 F.3d 1297 (Fed. Cir. 2001); Ventana Medical Systems, Inc. v. Biogenex Laboratories, Inc., 473 F.3d 1173 (Fed. Cir. 2006). In Hakim v. Cannon Avent Gp., PLC., 479 F.3d 1313 (Fed. Cir. 2007), for example, narrowing arguments made in a parent case that were not expressly rescinded during the prosecution of the continuation application operated to narrow the claim: "Although a disclaimer made during prosecution can be rescinded, permitting recapture of the disclaimed scope, the prosecution history must be sufficiently clear to inform the examiner that the previous disclaimer, and the prior art . . . may need to be re-visited." Id. at 1318.
If there are statements in an ancestor application that a drafter wants to rescind, such action must be very clear to fulfil the public notice function but also must not jeopardize the priority claim to the ancestor application.
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