IP Verse

Charged Depth Filtration Of Antigen-Binding Proteins

Patent No. US11098079 (titled "Charged Depth Filtration Of Antigen-Binding Proteins") was filed by Amgen Inc on Aug 12, 2016.

What is this patent about?

’079 is related to the field of therapeutic protein production, specifically addressing the issue of antibody reduction during manufacturing. Antibodies, crucial for treating various diseases, are often produced in cell culture. However, the production and purification processes can inadvertently lead to the reduction of disulfide bonds within the antibody structure, compromising its stability and efficacy. This reduction results in antibody fragments and aggregates, necessitating methods to re-oxidize these partially reduced antibodies to ensure a stable and effective pharmaceutical formulation.

The underlying idea behind ’079 is that contacting an aqueous solution containing antibody molecules with a charged depth filter promotes the re-oxidation of the reduced disulfide bonds. This re-oxidation process restores the structural integrity of the antibody, mitigating fragmentation and aggregation. The inventors discovered that charged depth filters, unlike standard filters, possess a unique ability to facilitate this re-oxidation, leading to a more stable and therapeutically potent antibody product.

The claims of ’079 focus on a method for producing an aqueous formulation of an antigen-binding protein. This involves contacting a solution of antigen-binding protein molecules with a charged depth filter to create a filtrate, followed by incubating the filtrate for at least four hours. The key outcome is a decrease of at least 20% in the percentage of reduced antigen-binding protein molecules in the filtrate after incubation, compared to the initial solution. Some claims specify the use of non-reduced capillary electrophoresis with sodium dodecyl sulfate (nrCE-SDS) to measure this reduction, and others specify the charged depth filter must contain copper ions.

In practice, the aqueous solution containing the antibody is passed through a charged depth filter, which contains a porous matrix with a positive charge, often due to the presence of metal ions like copper. This interaction with the charged filter matrix somehow facilitates the re-formation of disulfide bonds, effectively reversing the reduction process. The filtrate is then incubated for at least four hours to allow the re-oxidation process to complete, resulting in a solution with a significantly lower percentage of reduced antibody molecules. This incubation step is crucial for achieving the desired level of re-oxidation.

This method differentiates itself from prior approaches by utilizing the unique properties of charged depth filters. Traditional methods, such as air sparging or chilling, have proven insufficient in preventing or reversing antibody reduction. The charged depth filter provides a more effective means of re-oxidation, leading to a more stable and therapeutically potent antibody product. The use of a charged depth filter, particularly one containing copper ions, offers a significant advantage over conventional filtration techniques in maintaining the integrity and efficacy of therapeutic antibodies during manufacturing.

How does this patent fit in bigger picture?

Technical landscape at the time

In the mid-2010s when ’079 was filed, therapeutic proteins were typically produced in mammalian cell culture and purified using filtration and chromatography. At a time when protein stability depended heavily on disulfide bonds, hardware and software constraints made maintaining the structural integrity of these bonds during production and purification non-trivial.

Novelty and Inventive Step

The examiner approved the application because the applicant amended a claim to specify that the amount of reduced disulfide bonds in the antigen-binding protein is decreased by at least 15%. The examiner stated that this overcame a previous rejection. The examiner also noted that the closest prior art did not teach incubating the filtrate for at least four hours, wherein the percentage of reduced antigen-binding protein molecules in the filtrate after the incubating step is decreased.

Claims

This patent contains 40 claims, with independent claims numbered 1, 2, 29, 32, 35, and 38. The independent claims are directed to methods of producing aqueous formulations or enhancing re-oxidation of antigen-binding proteins using charged depth filters and incubation steps. The dependent claims generally specify further details, conditions, components, or steps related to the methods described in the independent claims.

Key Claim Terms New

Definitions of key terms used in the patent claims.

Term (Source)Support for SpecificationInterpretation
Antigen-binding protein molecules
(Claim 1, Claim 2, Claim 29, Claim 32, Claim 35, Claim 38)		“The term “antigen-binding protein” refers to a protein or polypeptide that comprises an antigen-binding region or antigen-binding portion that has a strong affinity for another molecule to which it binds (antigen). Antigen-binding proteins encompass antibodies, peptibodies, antibody fragments, antibody derivatives, antibody analogs, fusion proteins (including single-chain variable fragments (scFvs) and double-chain (divalent) scFvs), and antigen receptors including chimeric antigen receptors (CARs).”Proteins or polypeptides that comprise an antigen-binding region or portion that has a strong affinity for another molecule to which it binds (antigen).
Charged depth filter
(Claim 1, Claim 2, Claim 29, Claim 32, Claim 35, Claim 38)		“The term “charged depth filter” or “depth filter” refers to a filter comprising a) porous matrix (e.g., 2 mm to 5 mm thick matrix) that filters a solution based on physical capture within the matrix channels and/or electrokinetic adsorption, e.g., due to a charge on the matrix. A variety of positively charged ions, preferably metal ions, are suitable for use in such a filter. Charged depth filters are available commercially from, for example, Cuno, Inc. (e.g., ZETA PLUS S series, ZETA PLUS SP series, ZETA PLUS LP series, ZETA PLUS CP series, ZETA PLUS LP BC series), EMD Millipore (e.g., D0HC, C0HC, F0HC, A1HC, B1HC, X0HC), Sartorius AG, and Pall Corporation (e.g., SEITZ P series, SEITZ K series, SUPRADUR series, STAX series, SUPRACAP Series, SUPRAPAK series, SUPRADISC series).”A filter with a porous matrix (2-5 mm thick) that filters a solution by physical capture and/or electrokinetic adsorption due to a charge on the matrix.
Copper ion
(Claim 35, Claim 38)		“In some embodiments, the charge depth filter comprises at least one metal ion selected from the group consisting of sodium, calcium, magnesium, mercury, chromium, cadmium, aluminum, potassium, lead, arsenic, cobalt, iron, manganese, titanium, zinc, nickel, copper, and combinations thereof. In another aspect, the charged depth filter comprises one of the following combinations of metals: 1) copper and cobalt, 2) copper and cadmium, 3) cobalt and cadmium, or 4) copper, cobalt, and cadmium. In some embodiments, the metal (or one or more or all metals in a combination of metals) has a +2 or higher oxidation state (such as +3 or +4).”A positively charged copper atom.
Non-reduced capillary electrophoresis with sodium dodecyl sulfate
(Claim 29, Claim 32)		“One method of identifying size variants and quantifying the amount of partially reduced antigen-binding protein molecules in a sample comprises using nrCE-SDS to determine the percentage of pre-peak species corresponding to antigen-binding protein fragments (see, e.g., Guo et al., Electrophoresis. 29(12):2550-6 (2008)). Generally, non-reducing buffer is added to a sample. After incubation at high temperature, the samples are injected into a silica capillary. The separation is performed using a capillary electrophoresis sodium dodecyl sulfate (CE-SDS) gel, and effective voltage and detection is performed, for example, at 220 nm by UV absorbance.”A method of identifying size variants and quantifying the amount of partially reduced antigen-binding protein molecules in a sample by determining the percentage of pre-peak species corresponding to antigen-binding protein fragments.
Reduced antigen-binding protein molecules
(Claim 1, Claim 29, Claim 35)		“The structure and stability of antigen-binding protein molecules depend heavily on the disulfide bonds that link the two heavy chains and the heavy and light chains in each antigen-binding protein molecule, however, during the production and purification process, one or more disulfide bonds can be reduced to free thiol groups. Reduction of the inter-chain disulfide bonds weakens the structural integrity of the antigen-binding protein molecule and can lead to antigen-binding protein fragments (e.g., light chain, heavy chain, and their combinations) and/or antigen-binding protein aggregates, which impair the biological functions of the antigen-binding proteins and consequently, their therapeutic efficacy.”Antigen-binding protein molecules in which one or more disulfide bonds have been reduced to free thiol groups.

Litigation Cases New

US Latest litigation cases involving this patent.

Case NumberFiling DateTitle
1:25-cv-17596Nov 14, 2025AMGEN INC. et al v. ALKEM LABORATORIES LTD. et al
1:25-cv-17278Nov 6, 2025AMGEN INC. v. AMNEAL PHARMACEUTICALS, INC.
1:25-cv-17277Nov 6, 2025AMGEN INC. v. DR. REDDY'S LABORATORIES LTD.
1:25-cv-13358Jul 16, 2025Amgen Inc. V. Biocon Biologics, Inc.
1:25-cv-11867Jun 30, 2025Amgen Inc. V. Biocon Biologics, Inc.
1:25-cv-01080Feb 7, 2025Amgen Inc. V. Fresenius Kabi Usa, Llc

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US11098079

AMGEN INC
Application Number
US15751231
Filing Date
Aug 12, 2016
Status
Granted
Expiry Date
Jul 21, 2037
External Links
Slate, USPTO, Google Patents