Fed. Cir. reverses DC and finds Amneal’s Sensipar®-related product infringes Amgen ‘405 patent

Amgen Inc. v. Amneal Pharm., Pirimal, et al., Zydus Pharm., Cadila et al.

Docket Nos. 2018-2414, 2019-1086
January 7, 2020

Brief Summary: DC claim construction reversed (“composition comprising” not closed to other components); no infringement by Amneal reversed; no infringement by Pirimal affirmed; Amneal); infringement by Zydus affirmed.

Summary: Amgen appealed DC judgment that neither Amneal nor Pirimal infringes certain claims of US 9,375,405 relating to its Sensipar® product for secondary hyperparathyroidism (rapid dissolution cinacalcet hydrochloride, NDA 21688 which also lists US 7,829,595). Zydus and Cadila (“Zydus”) cross-appealed DC judgment that they do infringe certain ‘405 claims. Claim 1 of the ‘405 patent claims a “composition comprising:” a) about” 10-40% cinacalcet HCl (“about” 20-100 mg), b) “about” 45-85% by weight of selected diluents, c) “about” 1-5% by weight of “at least one” of the listed binders, and d) “about” 1-10% of “at least one” of the listed disintegrants. The FC panel explains that during prosecution Amgen added the “narrower” 20-100 mg limitation (and argument) in response to a prior art rejection (the “Cinacalcet Amendment”), which was followed by an Examiner’s Amendment that “revised the binder and disintegrant limitations into their current, Markush group format.” The claims were then allowed since “the closest prior art did not disclose or render obvious the ‘combination of components…in the amounts…set forth in claim 2” (‘405 claim 1). Amgen then filed multiple RCEs citing additional references and updates regarding revocation of a related European patent, including a “Preliminary Amendment” stating that the Examiner’s 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.” The DC found that Amneal and Piramal did not infringe because their products do “not meet the binder and disintegrant limitations” or “binder limitations”, respectively, which the DC construed as “closed” Markush groups (Multilayer Stretch, Fed. Cir. 2016 (“‘comprising,’ followed by ‘consisting of’ terminology”)) ((Amgen accepted the Examiner’s narrowing amendment; e.g., Amneal’s Opadry includes more than HPMC). The DC found Zydus infringed as its product included starch as a diluent which is in the ‘405 claimed diluent Markush group. In this appeal, Amgen argued its use of “‘comprising’…renders the claim open-ended” and “‘consisting of’…only applies to the group from which ‘at least one’ binding or disintegrant must be selected” and that the “at least one” language “would be meaningless if the groups are closed to additional binders and disintegrants” (as would “mixtures thereof”; citing Bitcon, Fed. Cir. 2006; Amneal et al. citing Shire, Fed. Cir. 2017 (“‘consisting of’ is closed to unrecited elements”)). The FC panel explained that this case asked “whether the ‘binder’ or ‘disintegrant’ limitations are written to preclude other binders and disintegrants”, and concluded “they are not” (unlike Multilayer or Shire which focused on one sub-limitation, not the “composition comprising” as here (Wis. Alumni, Fed. Cir. 2018; Multilayer). Based on its construction, the FC panel reversed the finding of no infringement by Amneal because “HPMC is present in Amneal’s formulation”. However, it found Amgen’s doctrine of equivalence arguments regarding Piramal’s product to be “barred by prosecution history estoppel” and therefore affirmed no infringement (e.g., Amgen accepted the Examiner’s Amendment and made the “to better define the” claims statement “over eight months” later; not tangential (Intervet, Fed. Cir. 2010). The FC panel also affirmed the DC decision that Zydus’s product infringed since “the pregelatinized starch in” it “functions as a diluent.”

This entry was posted in Claim Construction, Generics / ANDA, Infringement. Bookmark the permalink.

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