328 F. Supp. 3d 373
D. Del.2018Background
- Amgen owns U.S. Patent No. 9,375,405, claiming immediate‑release pharmaceutical compositions of cinacalcet HCl with specified weight ranges and closed Markush lists for diluents, binders, and disintegrants (claim 1 and dependents).
- Multiple ANDA defendants (Amneal, Watson, Piramal, Zydus, others) sought FDA approval for generic cinacalcet; Amgen sued for infringement under the Hatch‑Waxman framework (35 U.S.C. § 271(e)(2)).
- Court previously construed Markush groups for binders and disintegrants as closed: literal infringement requires accused product’s binders/disintegrants to be members of the claimed lists.
- Prosecution history: Examiner’s Amendment narrowed the claims by importing specific Markush lists for binders and disintegrants; allowance rested on the combination and amounts of components to overcome prior‑art obviousness rejections.
- At bench trial court evaluated literal infringement and doctrine of equivalents; Amgen’s expert testimony was often inconsistent with the court’s claim construction or lacked particularized limitation‑by‑limitation analysis.
Issues
| Issue | Plaintiff's Argument | Defendant's Argument | Held |
|---|---|---|---|
| Whether Amneal’s product infringes claim 1 (binder = Opadry) | Opadry is HPMC (a listed binder) or equivalent to HPMC | Opadry is a distinct co‑processed product (HPMC + PEGs) and not listed; differences are substantial | No infringement: Opadry is not HPMC and Amgen failed to prove equivalence (insufficient particularized testimony; contrary evidence showed distinct composition and binding mechanism) |
| Whether Amneal’s pregelatinized starch functions as a claimed disintegrant | Pregelatinized starch does not act as disintegrant in Amneal’s formulation (crospovidone does) | Pregelatinized starch functions as a secondary/intragranular disintegrant | No infringement: evidence (formulation percentages, intragranular/extragranular placement, ANDA tests) shows pregelatinized starch functions as disintegrant and is an unlisted disintegrant under the closed Markush list |
| Whether Watson’s L‑HPC disintegrant is equivalent to claimed disintegrants | L‑HPC is a "superdisintegrant" equivalent to the claimed disintegrants (function‑way‑result and later insubstantial‑differences theories) | L‑HPC differs in class, mechanism, particle shape, chemistry, and potency; not a superdisintegrant | No infringement: Amgen failed both tests—no particularized FWR proof; literature and expert testimony show different mechanisms and substantial differences under insubstantial‑differences test |
| Whether prosecution history estoppel bars Amgen from asserting equivalents against Piramal’s pregelatinized starch binder | Equivalents (cold‑water soluble fraction of pregelatinized starch ≈ povidone) are tangential to the Examiner’s Amendment | Examiner’s Amendment narrowed binders/disintegrants to obtain allowance; estoppel applies to equivalents within surrendered territory | Estoppel applies: patentee surrendered equivalents in narrowing to overcome prior art, precluding equivalents argument for pregelatinized starch as binder; no infringement |
| Whether Zydus’s product infringes claim 1 (pregelatinized starch function) | Pregelatinized starch should be split into fractions; cold‑water soluble fraction acts as binder (unlisted) so Amgen’s positions vary | Zydus treats pregelatinized starch as diluent; defendants argue it functions as binder in some contexts; evidence and percolation theory predict function by concentration | Literal infringement found as to Zydus: court rejects fractionation theory; percolation/context controls function—Zydus’s use (11%/formulation context) supports diluent interpretation earlier but court concludes on the record that Zydus’s formulation literally meets claim 1; Amgen failed to prove certain other asserted dependent claims |
Key Cases Cited
- Exergen Corp. v. Wal‑Mart Stores, Inc., 575 F.3d 1312 (Fed. Cir. 2009) (claim construction at trial binds expert testimony and trial evidence)
- Markman v. Westview Instruments, Inc., 52 F.3d 967 (Fed. Cir. 1995) (two‑step infringement analysis: construction then comparison)
- Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002) (prosecution history estoppel presumption when claims are narrowed for patentability)
- AquaTex Indus., Inc. v. Techniche Solutions, 479 F.3d 1320 (Fed. Cir. 2007) (doctrine of equivalents requires particularized limitation‑by‑limitation testimony)
- SmithKline Diagnostics, Inc. v. Helena Lab. Corp., 859 F.2d 878 (Fed. Cir. 1988) (patentee must prove each claim limitation is present literally or by equivalents)
- Wahpeton Canvas Co. v. Frontier, Inc., 870 F.2d 1546 (Fed. Cir. 1989) (if independent claim not infringed, dependent claim cannot be infringed)
- Mylan Institutional LLC v. Aurobindo Pharma Ltd., 857 F.3d 858 (Fed. Cir. 2017) (equivalence tests in chemical/pharmaceutical contexts; relevance of insubstantial‑differences test)
- Ranbaxy Pharm., Inc. v. Apotex, Inc., 350 F.3d 1235 (Fed. Cir. 2003) (importing dependent‑claim limitations into independent claim during prosecution can create estoppel)