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Amgen Inc. v. Coherus BioSciences, Inc.

United States Court of Appeals for the Federal Circuit

July 29, 2019, Decided



 [*1156]  Stoll, Circuit Judge.

Amgen Inc. and Amgen Manufacturing Ltd. (collectively, "Amgen") sued Coherus BioSciences Inc. for patent infringement in the District of Delaware. The district court dismissed Amgen's complaint for failure to state a claim, and Amgen appeals. Because prosecution history estoppel bars Amgen from succeeding on its infringement claim under the doctrine of equivalents, we affirm the order of the district court.


Recombinant therapeutic proteins are a class of biologic medicines that are manufactured [**2]  inside living cells. Before a protein can be therapeutically useful, it must first be purified from contaminants. Amgen's U.S Patent No. 8,273,707 claims methods of purifying proteins using hydrophobic interaction chromatography ("HIC"). A HIC column contains a solid, hydrophobic matrix and "is used to separate proteins on the basis of hydrophobic interactions between the hydrophobic moieties of the protein and insoluble, immobilized hydrophobic groups on the matrix." '707 patent col. 1 ll. 36-39. In a HIC purification, a buffered salt solution containing the desired protein and associated impurities is first poured onto a HIC column. Id. at col. 1 ll. 40-41. This is known as the "loading" step. The salt in the buffer exposes the hydrophobic regions of the protein and causes them to adsorb (i.e., attach) onto the hydrophobic groups on the column matrix. See id. at col. 1 ll. 41-44. The impurities are then washed out of the column with a buffered salt solution while the desired protein remains attached to the matrix. See id. at col. 4 ll. 27-29. Finally, molecules of the desired protein are detached (or "eluted") by pouring a buffer solution with a lower salt concentration through the column. See id. at col. 1 ll. 44-49. [**3]  "Usually, a decreasing salt gradient is used to elute proteins from a column. As the ionic strength decreases, the exposure of the hydrophilic regions of the protein increases and proteins elute from the column in order of increasing hydrophobicity." Id. at col. 1 ll. 45-49.

During the loading step, only a finite amount of protein can bind to the matrix. If too much protein is loaded on the column, "'breakthrough' or loss of protein to the solution phase before elution" will occur. Id. at col. 3 ll. 40-41. The '707 patent claims a process that reduces breakthrough, or in other words, increases the "dynamic capacity" of a HIC column. Dynamic capacity refers to "the maximum amount of protein in solution which can be loaded onto a column without significant breakthrough or leakage of the protein into the solution phase of a column before elution." Id. at col. 3 l. 65-col. 4 l. 3.

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931 F.3d 1154 *; 2019 U.S. App. LEXIS 22394 **; 2019 U.S.P.Q.2D (BNA) 279245; 2019 WL 3403371


Prior History:  [**1] Appeal from the United States District Court for the District of Delaware in No. 1:17-cv-00546-LPS, Chief Judge Leonard P. Stark.

Amgen Inc. v. Coherus Biosciences, Inc., 2018 U.S. Dist. LEXIS 56320 (D. Del., Mar. 26, 2018)

Disposition: AFFIRMED.


salt, combinations, protein, column, estoppel, dynamic, sulfate, surrendered, acetate, citrate, hydrophobic, recited, disclose, infringement, Declaration, patent, unmistakable, elution, doctrine of equivalents, district court, manufacturing, invention, buffer, matrix, prior art, argument-based, chromatography, concentration, interaction, unclaimed

Civil Procedure, Appeals, Standards of Review, De Novo Review, Patent Law, Jurisdiction & Review, Defenses, Demurrers & Objections, Motions to Dismiss, Failure to State Claim, Infringement Actions, Prosecution History Estoppel, Fact & Law Issues, Abandonment & Amendment, Prosecution History Estoppel, Prosecution Related Arguments & Remarks