Transitional terms in patent law (conventionally, "comprising," "consisting of," and the more arcane "consisting essentially of") have their own provenance and meaning, denoting limitations that are "open" (comprising) or "closed" (consisting). But how should a court construe instances where these terms seem to be at odds with one another? The Federal Circuit provided an answer, at least with regard to the interplay between "comprising" and Markush group language ("selected from the group consisting of") in one of its first opinions of the New Year, Amgen Inc. v. Amneal Pharmaceuticals LLC.
The case arose in ANDA litigation over generic versions of Amgen's Sensipar® formulation for treating "secondary hyperparathyroidism in adult patients with chronic kidney disease who are on dialysis and to treat hypercalcemia in patients with parathyroid cancer and primary and secondary hyperparathyroidism." Amneal (and its affiliated companies), Piramal Healthcare UK Ltd., and Zydus Pharmaceuticals (and its affiliated companies) each filed an ANDA to market a generic version of the drug, and Amgen brought suit, asserting various claims of U.S. Patent No. 9,375,405 against the three defendants (claims 1, 2-4, 6, 8-12, and 14-18 against Amneal, claim 1-6 and 8-20 against Piramal, and claims 1-4, 6, 8-9, 15-17, and 19 against Zydus). The parties agreed (for the purposes of the appeal) that claim 1 was representative:
A pharmaceutical composition comprising:
(a) from about 10% to about 40% by weight of cinacalcet HCl in an amount of from about 20 mg to about 100 mg;
(b) from about 45% to about 85% by weight of a diluent selected from the group consisting of microcrystalline cellulose, starch, dicalcium phosphate, lactose, sorbitol, mannitol, sucrose, methyl dextrins, and mixtures thereof,
(c) from about 1% to about 5% by weight of at least one binder selected from the group consisting of povidone, hydroxypropyl methylcellulose, hydroxypropyl cellulose, sodium carboxymethylcellulose, and mixtures thereof; and
(d) from about 1% to 10% by weight of at least one disintegrant selected from the group consisting of crospovid[o]ne, sodium starch glycolate, croscarmellose sodium, and mixtures thereof,
wherein the percentage by weight is relative to the total weight of the composition, and wherein the composition is for the treatment of at least one of hyperparathyroidism, hyperphosphonia, hypercalcemia, and elevated calcium phosphorus product.
The District Court bifurcated proceedings and determined infringement first. The panel opinion states that "[t]he prosecution history is particularly relevant to [this] appeal." The relevant portions of this history involved introduction of the Markush groups in subparts (b), (c), and (d), which were not recited in the claim as filed. The applicant introduced this language into subpart (b) and the Examiner (by Examiner's amendment) introduced the language into subparts (c) and (d) as a condition for allowance to overcome rejections over the prior art (to which the applicant acquiesced). The significance of this history before the District Court related to whether or not the claim elements should be open to the presence of other components in formulations that would be infringing; Amgen contended such infringing formulations could comprise these unrecited components and the District Court disagreed. According to the opinion, the District Court held that "Amgen ha[d] not overcome the very strong presumption that the Markush groups for the binder and disintegrant elements are closed to unrecited binders and disintegrants," relying on Multilayer Stretch Cling Film Holdings, Inc. v. Berry Plastics Corp., 831 F.3d 1350 (Fed. Cir. 2016). Under this construction, the District Court found that Amneal did not infringe because its accused formulation contained as a binder Opadry Clear YS-1-7006, a product that contains hydroxypropyl methylcellulose ("HPMC"), polyethylene glycol 400, and polyethylene glycol 8000, which was not recited in subpart (c) (which recited HPMC).
Similarly, the District Court found that Piramal's accused formulation used pregeletinized starch as a binder which the District Court held was not equivalent to povidone, a compound recited in the Markush language recited in subpart (c) of the claim. That Amgen accepted the Examiner's amendment to obtain allowance of the claim raised prosecution history estoppel that precluded the District Court from considering any purported equivalents to the compounds expressly recited in the claim according to the District Court.
On the other hand, the District Court found that Zydus's accused formulation was infringing under § 271(e)(2) because the function of pregelatinized starch in its formulation was as a diluent, and starch was recited as a diluent in the claim. Thus, the District Court found Zydus literally infringed the claim.
The Federal Circuit vacated and remanded as to the District Court's decision that Amneal did not infringe based on incorrect claim construction, but affirmed with regard to Piramal's non-infringement under the doctrine of equivalents and Zydus's literal infringement. The opinion notes that, "as a preliminary matter," the panel needed to consider its jurisdiction over Zydus, because Zydus had pending defenses and counterclaims of invalidity against Amgen and thus the District Court's judgment was not final. The opinion further noted, however, that Zydus's counsel at oral argument agreed to abandon these defenses should the Federal Circuit affirm the District Court's infringement decision, resolving any jurisdictional concerns.
Regarding the District Court's claim construction, that the presence of the phrase "consisting of" in the Markush language introduced during prosecution prevented Amgen from extending its claim to formulations containing other elements, the Federal Circuit held that the District Court had "read more into Multilayer and Shire [Dev., LLC v. Watson Pharm., Inc., 848 F.3d 981, 984 (Fed. Cir. 2017)] than is properly found there." Further the opinion states that:
Multilayer and Shire did not hold broadly that, whenever "consisting of" Markush group language is present in a particular claim limitation, even when the limitation follows a general claim transition phrase of "comprising," all components of an accused product that perform the general function of the particular limitation must meet the requirements of that limitation, thus precluding components outside the Markush group. No such issue was presented in those cases. Rather, each decision held only that the terms of a particular claim limitation that used "consisting of" Markush group language were restricted to members of the Markush group.
Here, the question before the panel was whether the "binder" and "disintegrant" limitations, written in Markush format, precluded other binders or disintegrants from being in the claimed composition (or an accused infringing embodiment thereof), and the Federal Circuit held that they did not. The Court's explication of both Multilayer and Shire supported this conclusion (because if not, this panel could not overturn the earlier panels' decision to the contrary). The panel finds as a "critical[] differen[ce]" here that "[t]here is no language in Amgen's claim indicating that every binder or disintegrant in the claimed formulation must be within the Markush group" because the claim also recites "at least one" of a binder or disintegrant. Moreover, the opinion states that the remaining limitations in the claims with regard to these components "merely require that those particular binders or disintegrants meet the specified weight-percentage requirements," which the panel asserted "is not inconsistent with the overall composition containing other binders or disintegrants." Relying on the plain meaning of the claim language (and finding that the specification and prosecution history do not mandate a different conclusion), the Federal Circuit held that the Markush language is not sufficient to support the District Court's construction that the claims do not encompass formulations containing other disintegrants or binders.
The opinion also found it significant that the claims recite "comprising " with regard to the components contained in the claimed formulations. Having found nothing in the expressly recited limitations that would be "inconsistent with the presence of binders and disintegrants beyond those identified in those limitations" recited in Markush language, the panel further relied on Amgen's use of the term "comprising" to "reinforce[] the conclusion that the language of those limitations is best construed not to foreclose such additional binders and disintegrants."
Accordingly, the panel held that the claims properly construed do not preclude infringement if the accused formulation included an "additional component [that is] functionally similar to the component identified in the Markush group limitation," unless there was another basis, not found here, for such a finding. The panel found that the District Court's claim construction was incorrect and vacated the determination that Amneal's ANDA formulation did not infringe, remanding to the District Court for further proceedings based on the panel's construction.
The Federal Circuit also vacated the District Court's finding that Amneal's formulation, comprising Opadry, did not satisfy the claim limitation that an infringing formula comprise HPMC, holding that on remand the District Court should determine whether the amount of Opadry in Amneal's formulation comprises 1% to 5% by weight of HPMC.
Regarding Piramal's product, the question before the Court was whether Amgen was precluded by prosecution history estoppel from a finding that this formulation infringed under the doctrine of equivalents. The District Court found, and the Federal Circuit affirmed, that Amgen had narrowed the claims for "reasons related to patentability" by accepting the Examiner's amendment that inserted Markush language regarding the binder and disintegrant limitations. Thus, Amgen was estopped from asserting that the Piramal formulation's pregelatinized starch was an equivalent to the expressly recited povidone in its claims (despite a paper submitted on the record during prosecution after the Examiner issued a Notice of Allowance that "[t]hese amendments have not been made in response to a prior art rejection but rather to place the claims in proper format and to better define the claimed subject matter, including equivalents"). And the panel also found unavailing Amgen's argument that these amendments were tangential to patentability because they were made to avoid the prior art.
Finally, with regard to Zydus's product, the Federal Circuit affirmed the District Court's finding that its product would infringe Amgen's claims. In this case, Zydus's product comprised starch as a diluent, a component expressly recited amongst the Markush group of diluents in Amgen's claims. The panel did not find credible Amgen's expert testimony (proffered with regard to Piramal's product and asserted by Zydus against Amgen's infringement contentions) that starch was a binder and not a diluent (on the ground that the expert proffered inconsistent testimony, changing it somewhat three times). The panel held that the District Court did not err in it infringement finding and affirmed that Zydus's ANDA formulation literally infringed Amgen's asserted claims.
Amgen Inc. v. Amneal Pharmaceuticals LLC (Fed. Cir. 2020)
Panel: Circuit Judges Newman, Lourie, and Taranto
Opinion by Circuit Judge Lourie
