US20090294288A1 - High-sensitivity proteolysis assay - Google Patents

High-sensitivity proteolysis assay Download PDF

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US20090294288A1
US20090294288A1 US12/001,658 US165807A US2009294288A1 US 20090294288 A1 US20090294288 A1 US 20090294288A1 US 165807 A US165807 A US 165807A US 2009294288 A1 US2009294288 A1 US 2009294288A1
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gel
antibody
sample
substrate
sds
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Kimberly Margaret Louise May
Susan V. Cannon-Carlson
Brittany Charlotte Larkin
Collette Marie Cutler
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Merck Sharp and Dohme LLC
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Schering Corp
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Assigned to SCHERING CORPORATION reassignment SCHERING CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: MAY, KIMBERLY MARGARET LOUISE, CANNON-CARLSON, SUSAN V., CUTLER, COLLETTE MARIE, LARKIN, BRITTANY CHARLOTTE
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Priority to US13/343,274 priority patent/US8569007B2/en
Assigned to MERCK SHARP & DOHME CORP. reassignment MERCK SHARP & DOHME CORP. CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: SCHERING CORPORATION
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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
    • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
    • C12Q1/34—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving hydrolase
    • C12Q1/37—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving hydrolase involving peptidase or proteinase

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  • the present invention relates, inter alia, to assays and compositions for detecting proteolytic activity in a sample.
  • plant-derived hydrolysates are often added to the cell culture media in order to increase the titer.
  • the small peptide chains in the hydrolysates are derived from protease-driven degradation of soy and wheat by-products of the food industry which results in the unintended introduction of proteases to the culture.
  • the presence of the proteases leads to in culture degradation of the antibodies, particularly if engineered to be secreted into the culture. Later purification is also complicated if the proteases are not sufficiently inactivated or removed and are, instead, carried over, in an active form, to the purified product.
  • lot-to-lot variability may also be observed. The variability makes removal or inactivation of the proteases more difficult.
  • an enzyme often a papain-derivative, is added to a batch of soy, wheat, or rice.
  • the enzyme is allowed to digest the food material for a specific amount of time and is then, typically, heat inactivated via a pasteurization step.
  • heat inactivation of the enzyme is achieved using heat exchangers.
  • the contact time is minimal. For this reason, complete inactivation is not always successful.
  • the hydrolysates are then ultrafiltered with membranes ranging in size cut-off from 10 kDa to 50 kDa.
  • proteases in a peptide product can cause significant problems with respect to the quality and stability of the product over time.
  • Slow proteolytic degradation of the product is a problem that must be monitored in order to both track product quality and stability and to develop purification procedures for complete removal of protease contamination from the product.
  • There are known methods for detecting proteases in a sample however, the sensitivity of such assays is relatively low.
  • culture media vendors commonly use a fluorescence-based assay with a casein peptide substrate that emits fluorescence light when cleaved by a protease.
  • protease assays Since the quantity of protease present in a sample of purified antibody product is, generally, very low, the known protease assays are insufficient. There exists a need in the art for protease assays comprising sensitivity high enough to detect very low levels of protease activity in a sample.
  • the present invention provides a method for determining the presence of proteolytic activity (e.g., a protease) in a sample comprising incubating the sample with a substrate for said protease 8 or more hours and determining proteolysis of said substrate.
  • the method comprising the steps of: (a) combining the sample with a peptide substrate and, optionally, with a reducing agent; (b) incubating the sample for at least 8 hours at room temperature (e.g., about 22° C. or 28° C.
  • about 1 ⁇ g to 12 ⁇ g (e.g., 1 ⁇ g, 2 ⁇ g, 3 ⁇ g, 4 ⁇ g, 5 ⁇ g, 6 ⁇ g, 7 ⁇ g, 8 ⁇ g, 9 ⁇ g, 10 ⁇ g, 11 ⁇ g, 12 ⁇ g) of substrate is electrophoresed on the gel.
  • the pH of said sample and the substrate is 8.8.
  • the sample and the substrate are combined with a Tris pH 8.8 buffer.
  • the sample and substrate are incubated for 18 hours.
  • the substrate is an immunoglobulin polypeptide.
  • the concentration of the immunoglobulin in (a) is about 0.3 mg/ml to 1 mg/ml.
  • proteolysis is determined by SDS-polyacrylamide gel electrophoresis analysis.
  • the substrate is anti-IGF1R antibody or anti-IL10 antibody.
  • the sample is cellular growth media.
  • the growth media comprises a hydrolysate (e.g., a plant-derived hydrolysate).
  • the present invention also provides a method for producing an antibody comprising determining the presence of proteolytic activity in culture medium by the method set forth above and culturing host cells expressing the antibody in said medium and, optionally, isolating the antibody from the medium.
  • FIG. 1 Example of increased sensitivity with exposure time to sample buffer prior to boiling. Arrows indicate lanes of increased proteolysis with exposure time.
  • FIG. 2 Example of increased sensitivity with exposure time for non-reducing gels. Arrows indicate lanes of increased proteolysis with exposure time.
  • FIG. 3 Example of the effects of buffer pH for determining proteolytic activity. These samples were for anti-IL10. No protease activity was present in these samples, but the pH 6.8 buffer produced fragments that appeared as proteolysis, thereby producing false positives (arrows) as described in the text.
  • FIG. 4 The boiling time was optimized. Proteolytic enzymes are denatured after 5 minutes at 90° C. These samples were boiled immediately after sample preparation with the exception of Lane 9.
  • room temperature is known in the art and, in an embodiment of the invention, is about 23° C., 24° C. or 25° C.
  • proteolytic activity includes both proteolytic enzymes (proteases) as well as less specific factors which degrade or decrease the stability of polypeptides (e.g., heat, pH, physical forces).
  • the present invention provides a new and highly sensitive assay for determining the presence of proteases in a sample such as cellular growth media.
  • the assay is used to detect any protease including, but not limited to, thiolproteases, metalloproteases and serine proteases.
  • thiolprotease thioprotease, thiol peptidase; thiol proteinase or sulfhydryl protease
  • thiolproteases include, for example, any member of the papain family (e.g., cathepsin J and cathepsin C), caspases and calpains.
  • metalloproteases bind a divalent metal ion such as Zn 2+ or Co 2+ in their active site.
  • metalloproteases include, for example, ADAM 33, 30, 28, 25, 24, 21, 20, 19, 17, 15, 12, 10, 26a, aminopeptidase N, aminopeptidease G, and angiotensin-converting enzyme.
  • a serine protease is characterized by the presence of a serine residue in the active site of the enzyme.
  • serine proteases include, for example, chymotrypsin, trypsin, elastase and subtilisin.
  • the present invention provides a method for determining the presence of proteolytic activity in a sample following an overnight incubation of a sample for which the presence of the protease is being determined and a substrate of the protease (e.g., in an embodiment of the invention, at least about 8 hours, at least about 9 hours, at least about 10 hours, at least about 11 hours, at least about 12 hours, at least about 13 hours, at least about 14 hours, at least about 15 hours, at least about 16 hours, at least about 17 hours, at least about 18 hours or at least about 24 hours).
  • a substrate of the protease e.g., in an embodiment of the invention, at least about 8 hours, at least about 9 hours, at least about 10 hours, at least about 11 hours, at least about 12 hours, at least about 13 hours, at least about 14 hours, at least about 15 hours, at least about 16 hours, at least about 17 hours, at least about 18 hours or at least about 24 hours.
  • the present invention encompasses any method whereby protease activity in a sample is determined comprising the step of incubating the sample with a protease substrate overnight, followed by determination of degradation of the substrate.
  • the method comprises the steps of: (a) combining the sample with a polypeptide substrate and, optionally, with a reducing agent (e.g., dithiothreitol (DTT) or ⁇ -mercaptoethanol (BME)); (b) adjusting pH of the sample and substrate to about 8.8 (e.g., by adding a buffer such as Tris pH 8.8); (c) incubating the sample overnight, for example, for at least 12 hours; and (d) determining proteolysis of the substrate, for example, by electrophoretic analysis on an SDS-PAGE gel (e.g., including the steps of electrophoreses, staining the gel with a dye, such as coomassie brilliant blue and, optionally destaining the gel and, optionally, drying the gel and,
  • a reducing agent may or may not be combined with the sample and the substrate.
  • An embodiment of the invention also includes a method for determining non-protease mediated proteolysis.
  • a method for determining non-protease mediated proteolysis is similar to that set forth above, except that the method includes incubating the substrate (e.g., an antibody) under conditions whereby proteolysis is suspected to occur overnight.
  • the assay can be used to determine proteolytic degradation occurs under a given set of protease free buffer conditions, under high heat or extreme pH. Following incubation, proteolysis may be detected, e.g., by SDS-PAGE analysis.
  • a substrate for the protease to be determined can, in an embodiment of the invention, be any polypeptide.
  • the antibody can be used as the substrate.
  • SDS-PAGE stands for sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) and is useful for molecular weight analysis of proteins.
  • SDS is a detergent that dissociates and unfolds oligomeric proteins into its subunits. The SDS binds to the polypeptides to form complexes with fairly constant charge to mass ratios. The electrophoretic migration rate through a gel is therefore determined only by the size of the complexes.
  • Molecular weights are determined by simultaneously running marker proteins of known molecular weight.
  • Embodiments of the invention include methods wherein proteolysis is determined by continuous or discontinuous SDS-PAGE.
  • Continuous systems use the same buffer in both the gel and tank, while discontinuous buffer systems employ different buffers for tank and gel, and often two different buffers within the gel, with a third buffer in the tank.
  • discontinuous buffer systems employ different buffers for tank and gel, and often two different buffers within the gel, with a third buffer in the tank.
  • two sequential gels are typically used; the top gel, called the stacking gel, is, in some cases, slightly acidic (pH 6.8) and has a low (e.g., about 5%) acrylamide concentration to make a porous gel. Under these conditions proteins typically separate poorly but form thin, sharply defined bands.
  • the lower gel called the separating, or resolving gel
  • the lower gel is more basic (pH 8.8), and has a higher acrylamide content (e.g., 12%), which causes the gel to have narrower channels or pores.
  • acrylamide content e.g., 12%
  • the stacking gel comprises about 4% acrylamide whereas the resolving gel comprises about 6% to about 15% acrylamide (e.g., 6, 7, 8, 9, 10, 11, 12, 13, 14, 15).
  • a discontinuous gel may be described as follows: stacking gel percentage of acrylamide-resolving gel percentage of acrylamide.
  • a 4-12% discontinuous gel comprises a 4% stacking gel and a 12% resolving gel.
  • Protein indicator stain Common protein indicator stains are Coomassie Brilliant Blue (0.5% (mass/volume) in 50% methanol/water) and silver stain (e.g., silver nitrate based stain). Other stains include copper chloride (Lee et al., Anal. Biochem. 166: 308-312 (1987)).
  • a stained gel may be destained to remove dye present in the gel non-specifically.
  • a gel stained with coomassie blue can be destained in a methanol solution or a methanol/acetic acid solution.
  • Glycerol may optionally be added to the destaining solution. Destaining can be performed by simply soaking the stained gel in destaining solution at room temperature or heating the gel and destaining solution, for example, in a microwave oven.
  • a polyacrylamide gel may also be dried and fixed to a permanent substrate such as paper for long term storage. Drying and fixing are typically performed under vacuum and in the presence of heat.
  • a gel may be loaded with an indicator dye which allows visual evaluation of the progress of the electrophoresis.
  • an indicator dye such as bromophenol blue may be loaded onto a gel along with the sample.
  • the dye is combined directly with the sample being loaded onto the gel.
  • the sample may also be combined with a density agent, such as glycerol, which aids in keeping the sample from diffusing out of the well prior to application of the electrical current.
  • Buffer may also be used to stabilize the pH of the sample being run (e.g., Tris, e.g., Tris pH 8.8).
  • proteins Before a SDS-PAGE is run, proteins may be boiled in the presence or absence of a reducing agent, such as dithiothreitol (DTT) or 2-mercaptoethanol (beta-Mercaptoethanol/BME), which denatures the proteins and dissolves SDS in the sample.
  • a reducing agent such as dithiothreitol (DTT) or 2-mercaptoethanol (beta-Mercaptoethanol/BME), which denatures the proteins and dissolves SDS in the sample.
  • DTT dithiothreitol
  • BME 2-mercaptoethanol
  • the present invention comprises methods for expressing antibodies in cells incubated in growth media which has been evaluated for the present of protease activity. If no significant or detectable protease activity is present, then the growth media is used to propagate the cells.
  • anti-IGF1R antibody or “anti-IL-10 antibody” includes any such antibody.
  • the anti-IGF1R antibody is any set forth in published U.S. patent application no. US2004/0018191.
  • Any suitable method can be used to elicit an anti-IGF1R antibody.
  • Description of techniques for preparing monoclonal antibodies may be found in, e.g., Stites, et al. (eds.) BASIC AND CLINICAL IMMUNOLOGY (4th ed.) Lange Medical Publications, Los Altos, Calif., and references cited therein; Harlow and Lane (1988) ANTIBODIES: A LABORATORY MANUAL CSH Press; Goding (1986) MONOCLONAL ANTIBODIES: PRINCIPLES AND PRACTICE (2d ed.) Academic Press, New York, N.Y.
  • Mammalian cell lines available as hosts for expression of antibodies of the invention are well known in the art and include many immortalized cell lines available from the American Type Culture Collection (ATCC). These include, inter alia, Chinese hamster ovary (CHO) cells, NSO, SP2 cells, HeLa cells, baby hamster kidney (BHK) cells, monkey kidney cells (COS), human hepatocellular carcinoma cells (e.g., Hep G2), A549 cells, 3T3 cells, HEK-293 cells and a number of other cell lines.
  • Mammalian host cells include human, mouse, rat, dog, monkey, pig, goat, bovine, horse and hamster cells. Cell lines of particular preference are selected through determining which cell lines have high expression levels.
  • insect cell lines such as Sf9 cells, amphibian cells, plant cells and fungal cells.
  • immunoglobulins in bacterial cells e.g., E. coli
  • E. coli expression of immunoglobulins in bacterial cells, e.g., E. coli , is also of interest (see Cabilly, U.S. Pat. No. 4,816,567; and Queen et al. (1989) Proc. Nat'l Acad. Sci. USA 86:10029-10033).
  • Immunoglobulin/antibody chains can be expressed in a suitable cell by introduction of an expression plasmid into the cell, followed by culturing the cell in a suitable culture medium which has been previously determined, using a method of the present invention, to not contain significant levels of protease (e.g., no detectable levels of protease).
  • the antibodies are, in an embodiment of the invention, produced by culturing the host cells for a period of time sufficient to allow for expression of the antibody in the host cells or secretion of the antibody into the culture medium in which the host cells are grown.
  • Antibodies can be recovered from the culture medium using standard protein purification methods (e.g., chromatography (e.g., reverse phase chromatography, cation exchange, anion exchange, hydroxyapatite, protein A)). Further, expression of antibodies of the invention from production cell lines can be enhanced using a number of known techniques. For example, the glutamine synthetase gene expression system (the GS system) is a common approach for enhancing expression under certain conditions. The GS system is discussed in whole or part in connection with European Patent Nos. 0 216 846, 0 256 055, and 0 323 997 and European Patent Application No. 89303964.4. The use of matrix attachment regions (MARs) in expression plasmids has also been shown to increase expression levels.
  • MARs matrix attachment regions
  • a convenient plasmid system useful for producing an anti-IGF1R antibody or antigen-binding fragment thereof e.g., Fab, F(ab) 2 , Fv, ScFv, dsFv
  • Fab, F(ab) 2 , Fv, ScFv, dsFv is set forth in published U.S. application no. US2005/0176099 (see also WO2005/47512).
  • an anti-IGF1R antibody or antigen-binding fragment thereof comprises a mature 19D12/15H12 Light Chain-C, D, E or F (LCC, LCD, LCE or LCF) and/or a mature 19D12/15H12 heavy chain-A or B (HCA or HCB).
  • the antibody or fragment comprises the mature LCF and the mature HCA (LCF/HCA).
  • an IGF1R inhibitor that is administered to a patient in a method according to the invention is an isolated antibody that specifically binds to IGF1R that comprises one or more complementarity determining regions (CDRs) of 19D12/15H12 Light Chain-C, D, E or F and/or 19D12/15H12 heavy chain-A or B (e.g., all 3 light chain CDRs and all 3 heavy chain CDRs).
  • CDRs complementarity determining regions
  • amino acid and nucleotide sequences of the some antibody chains of the invention are shown below. Dotted, underscored type indicates the signal peptide. Solid underscored type indicates the CDRs. Plain type indicates the framework regions. Mature fragments lack the signal peptide.
  • the proteolytic activity of a sample of growth media was assayed using an anti-IL-10 or an anti-IGF1R monoclonal antibody as a polypeptide substrate.
  • the growth media used was a chemically defined media into which a hydrolysate was added.
  • the hydrolysate was the source of the proteolytic activity that was determined.
  • Tris pH 8.8 Dissolved 90.73 g Tris base in 400 ml DI H 2 O. Adjusted pH to 8.8 with hydrochloric acid. Brought solution to a volume of 500 ml with DI H 2 O. Stored at 4° C.
  • pH 8.8 Sample Buffer Combined the following: 228 ml of DI H 2 O, 50 ml glycerol, 50 ml 1.5M Tris pH 8.8, 50 ml 10% SDS solution, and 10 ml 0.05% bromophenol blue. Stored at 4° C.
  • Non-reducing sample buffer Novex Tris-Glycine SDS Sample Buffer 2 ⁇ (Invitrogen; Carlsbad, Calif.): 126 mM Tris HCl pH 6.8, 20% glycerol, 4% SDS, 0.005% bromophenol blue was purchased commercially.
  • the reducing or non-reducing buffers were combined with the media/antibody mixtures (above) in equal volumes and incubated overnight (18 hours) at room temperature (23° C.). After incubation for 5 hours or overnight (about 18 hours), the mixture was boiled at 90° C. for 5 minutes. The boiled mixture was then analyzed by SDS-PAGE. Approximately 10 ⁇ g of protein were loaded into each well of the gel. The mixtures were quickly boiled again immediately before loading onto the gel. Electrophoresis was performed with the XCell SurelockTM Mini-Cell system (Invitrogen; Carlsbad, Calif.) at a constant voltage of 125 mV for 90 minutes.
  • CD3 is chemically-defined cellular growth media which is commercially available from Sigma-Aldrich (St. Louis, Mo.). CD3 contains inorganic salts, HEPES and sodium bicarbonate buffers, essential and non-essential amino acids, vitamins, recombinant human insulin, other organic compounds, trace elements, and surfactants. CD3 does not contain antibiotics, antimycotics, L-glutamine, transferrin, hydrolysates, or other undefined nutrients or supplements. CD3 also contains no animal-derived components or components synthesized from animal-derived materials.
  • the results of the SDS-PAGE analysis are set forth in FIG. 4 .
  • the proteolytic activity in the sample was inactivated after 5 minutes of boiling. These data indicate that boiling the sample before an overnight incubation would render the sample free of protease activity and, thus, would not lead to accurate results with respect to measuring the protease activity in a sample. For this reason, omitting any boiling step prior to the overnight incubation of the sample and substrate is desirable.
  • the present protease assay was used to evaluate several culture components for proteolytic activity against anti-IGF1R antibody. Using inhibition experiments, it also demonstrates that the fragments detected are indeed from enzymes present in solution instead of being artifacts from the assay itself, as previously seen at pH 6.8.
  • Animal-component free C5467 CHO medium, animal-component free imMEDIAte AdvantageTM CHO medium (without aurintricarboxylic acid (ATA) or hydrolysates) and 1615 CHO medium supplement (Sterile filtered feed concentration containing amino acids, vitamins, recombinant human insulin, plant hydrolysates, trace elements and other organic compounds; lacking glucose, L-glutamine, phenol red, antibiotics, antimycotics, or transferrin hypoxanthine and thymidine) were obtained from Sigma-Aldrich (St. Louis, Mo.).
  • Hypep 4601S wheat hydrolysates were obtained from Kerry Biosciences (AH Almere, The Netherlands).
  • Ethylenediaminetetraacetic acid (EDTA), trans-epoxy-succinyl-L-leucylamido-(4-guanidino)butane (E-64), was obtained from EMD Biosciences.
  • the buffers were combined with the samples in equal volumes and allowed to sit overnight at room temperature before boiling. This increases the sensitivity of the assay for protease activity.
  • the samples were then boiled directly before submitting for SDS-PAGE.
  • E-64 was dissolved in DMSO and EDTA was dissolved in sterile distilled water. Samples were allowed to incubate overnight at room temperature. Samples were then combined in equal parts with anti-IGF1R drug substance to yield a final concentration of 0.5 mg/ml antibody. Reducing buffer was added in equal parts to the samples containing antibody. Following overnight incubation, these samples were then loaded onto gels for reducing SDS-PAGE for a final load of 10-12 ⁇ g of antibody. Inhibition studies were also performed with samples not containing antibody on the zymograms in order to determine the molecular weight of the inhibited protease. Concentrations of some thiol-proteases were predicted by inhibiting a papain control with E-64. All inhibitors were allowed to remain at room temperature with the samples overnight before loading onto the gels.

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US10087451B2 (en) 2006-09-22 2018-10-02 Aviex Technologies Llc Live bacterial vectors for prophylaxis or treatment
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US10590185B1 (en) 2009-02-09 2020-03-17 David Gordon Bermudes Protease inhibitor: protease sensitive expression system and method improving the therapeutic activity and specificity of proteins and phage and phagemids delivered by bacteria
US11485773B1 (en) 2009-02-09 2022-11-01 David Gordon Bermudes Protease inhibitor:protease sensitive expression system and method improving the therapeutic activity and specificity of proteins and phage and phagemids delivered by bacteria
US9657085B1 (en) 2009-02-09 2017-05-23 David Gordon Bermudes Protease inhibitor: protease sensitive expression system and method improving the therapeutic activity and specificity of proteins and phage and phagemids delivered by bacteria
US11219671B1 (en) 2010-02-09 2022-01-11 David Gordon Bermudes Protease inhibitor:protease sensitive expression system, composition and methods for improving the therapeutic activity and specificity of proteins delivered by bacteria
US9878023B1 (en) 2010-02-09 2018-01-30 David Gordon Bermudes Protease inhibitor: protease sensitive expression system composition and methods improving the therapeutic activity and specificity of proteins delivered by bacteria
US10857233B1 (en) 2010-02-09 2020-12-08 David Gordon Bermudes Protease inhibitor combination with therapeutic proteins including antibodies
US10364435B1 (en) 2010-02-09 2019-07-30 David Gordon Bermudes Immunization and/or treatment of parasites and infectious agents by live bacteria
US9486513B1 (en) 2010-02-09 2016-11-08 David Gordon Bermudes Immunization and/or treatment of parasites and infectious agents by live bacteria
US9068187B1 (en) 2010-02-09 2015-06-30 David Gordon Bermudes Protease inhibitor: protease sensitivity expression system composition and methods improving the therapeutic activity and specificity of proteins delivered by bacteria
US10954521B1 (en) 2010-02-09 2021-03-23 David Gordon Bermudes Immunization and/or treatment of parasites and infectious agents by live bacteria
US10501746B1 (en) 2013-02-14 2019-12-10 David Gordon Bermudes Bacteria carrying bacteriophage and protease inhibitors for the treatment of disorders and methods of treatment
US9593339B1 (en) 2013-02-14 2017-03-14 David Gordon Bermudes Bacteria carrying bacteriophage and protease inhibitors for the treatment of disorders and methods of treatment
US11827890B1 (en) 2013-02-14 2023-11-28 David Gordon Bermudes Bacteria carrying bacteriophage and protease inhibitors for the treatment of disorders and methods of treatment
US10828350B1 (en) 2014-02-14 2020-11-10 David Gordon Bermudes Topical and orally administered protease inhibitors and bacterial vectors for the treatment of disorders and methods of treatment
US9737592B1 (en) 2014-02-14 2017-08-22 David Gordon Bermudes Topical and orally administered protease inhibitors and bacterial vectors for the treatment of disorders and methods of treatment
US11129906B1 (en) 2016-12-07 2021-09-28 David Gordon Bermudes Chimeric protein toxins for expression by therapeutic bacteria
US11180535B1 (en) 2016-12-07 2021-11-23 David Gordon Bermudes Saccharide binding, tumor penetration, and cytotoxic antitumor chimeric peptides from therapeutic bacteria

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