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EP0614375A1 - Procede de preparation de conjugues d'agents diagnostiques ou neuropharmaceutiques-anticorps specifiques de recepteur de transferine - Google Patents

Procede de preparation de conjugues d'agents diagnostiques ou neuropharmaceutiques-anticorps specifiques de recepteur de transferine

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Publication number
EP0614375A1
EP0614375A1 EP93900677A EP93900677A EP0614375A1 EP 0614375 A1 EP0614375 A1 EP 0614375A1 EP 93900677 A EP93900677 A EP 93900677A EP 93900677 A EP93900677 A EP 93900677A EP 0614375 A1 EP0614375 A1 EP 0614375A1
Authority
EP
European Patent Office
Prior art keywords
antibody
brain
neuropharmaceutical
constant region
diagnostic agent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP93900677A
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German (de)
English (en)
Inventor
Phillip M. Friden
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Alkermes Inc
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Alkermes Inc
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Filing date
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Application filed by Alkermes Inc filed Critical Alkermes Inc
Publication of EP0614375A1 publication Critical patent/EP0614375A1/fr
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
    • C07K16/18—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans
    • C07K16/28—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants
    • C07K16/2881—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against CD71
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
    • A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
    • A61K47/68—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an antibody, an immunoglobulin or a fragment thereof, e.g. an Fc-fragment
    • A61K47/6835—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an antibody, an immunoglobulin or a fragment thereof, e.g. an Fc-fragment the modifying agent being an antibody or an immunoglobulin bearing at least one antigen-binding site
    • A61K47/6849—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an antibody, an immunoglobulin or a fragment thereof, e.g. an Fc-fragment the modifying agent being an antibody or an immunoglobulin bearing at least one antigen-binding site the antibody targeting a receptor, a cell surface antigen or a cell surface determinant
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/20—Immunoglobulins specific features characterized by taxonomic origin
    • C07K2317/24—Immunoglobulins specific features characterized by taxonomic origin containing regions, domains or residues from different species, e.g. chimeric, humanized or veneered
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/70—Immunoglobulins specific features characterized by effect upon binding to a cell or to an antigen
    • C07K2317/77—Internalization into the cell
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2319/00—Fusion polypeptide
    • C07K2319/01—Fusion polypeptide containing a localisation/targetting motif
    • C07K2319/02—Fusion polypeptide containing a localisation/targetting motif containing a signal sequence

Definitions

  • the capillaries that supply blood to the tissues of the brain constitute the blood brain barrier (Goldstein et al. (1986) Scientific American 255:74-83; Pardridge, W.M. (1986) Endocrin. Rev. 7:314-330).
  • the endothelial cells which form the brain capillaries are different from those found in other tissues in the body. Brain capillary endo ⁇ thelial cells are joined together by tight inter ⁇ cellular junctions which form a continuous wall against the passive movement of substances from the blood to the brain. These cells are also different in that they have few pinocytic vesicles which in other tissues allow somewhat unselective transport across the capillary wall.
  • the blood-brain barrier functions to ensure that the environment of the brain is constantly controlled.
  • the levels of various substances in the blood such as hormones, amino acids and ions, undergo frequent small fluctuations which can be brought about by activities such as eating and exercise (Goldstein et al_, cited supra) . If the brain were not protected by the blood brain barrier from these variations in serum composition, the result could be uncontrolled neural activity.
  • the isolation of the brain from the bloodstream is not complete. If this were the case, the brain would be unable to function properly due to a lack of nutrients and because of the need to exchange chemicals with the rest of the body.
  • the presence of specific transport systems within the capillary endothelial cells assures that the brain receives, in a controlled manner, all of the compounds required for normal growth and function. In many instances, these transport systems consist of membrane-associated receptors which, upon binding of their respective ligand, are internalized by the cell (Pardridge, .M. , cited supra) . Vesicles containing the receptor-ligand complex then migrate to the abluminal surface of the endothelial cell where the ligand is released.
  • the problem posed by the blood-brain barrier is that, in the process of protecting the brain, it excludes many potentially useful therapeutic agents.
  • each modification has to be tested individually on each drug and the modification can alter the activity of the drug.
  • the modification can also have a very general effect in that it will increase the ability of the compound to cross all cellular membranes, not only those of brain capillary endothelial cells.
  • the present invention pertains to a method for delivering a neuropharmaceutical or diagnostic agent across the blood brain barrier to the brain of a hpst.
  • the method comprises administering to the host a therapeutically effective amount of an antibody- neuropharmaceutical or diagnostic agent conjugate wherein the antibody is reactive with a transferrin receptor and the antibody is a chimera between the variable region from one animal source and the constant region from a different animal source.
  • the conjugate is administered under conditions whereby binding of the antibody to a transferrin receptor on a brain capillary endothelial cell occurs and the neuropharmaceutical agent is transferred across the blood brain barrier in a pharmaceutically active form.
  • a delivery system comprising an antibody reactive with a transferrin receptor linked to a * neuropharmaceutical agent and methods for treating hosts afflicted with a disease associated with a neurological disorder.
  • the antibody that is reactive with a transferrin receptor is a chimeric antibody.
  • This antibody is composed of a variable region, immunologically reactive with the transferrin receptor, that is derived from one animal source and a constant region that is derived from an animal source other than the one which provided the variable region.
  • the chimeric antibodies of this invention can exist either as isolated entities or as conjugates with a neuropharmaceutical agent for transferal across the blood brain barrier. In the latter mode, the chimeric antibody-neuropharmaceut ⁇ ical agent conjugate forms a delivery system for delivering the neuropharmaceutical agent across the blood brain barrier.
  • the delivery system of the present invention is non-invasive and can utilize readily available antibodies reactive with a trans ⁇ ferrin receptor as carriers for neuropharmaceutical agents.
  • the delivery system is advantageous in that the antibodies are capable of transporting neuropharmaceutical agents across the blood brain barrier without being susceptible to premature release of the neuropharmaceutical agent prior to reaching the brain-side of the blood brain barrier.
  • a noncleavable linker can be used to link the neuropharmaceutical agent to the antibody.
  • Figure 1 is a graphic representation of rat brain uptake of 14C-labelled murine monoclonal antibody (OX-26) to rat transferrin receptor in rats where the percent injected dose of radiolabelled antibody per brain and per 55 ⁇ l of blood is plotted versus time post-injection.
  • OX-26 murine monoclonal antibody
  • Figure 2 is a histogram illustrating time dependent changes in the disposition of radiolabelled OX-26 between brain parenchyma and vasculature.
  • Figure 3 is a histogram illustrating the enhanced delivery of methotrexate across the blood-brain barrier when, administered as a conjugate with OX-26.
  • Figure 4 illustrates in three histograms (A,B and C) the distribution in the brain of both the antibody and the AZT components of an OX-26-AZT conjugate.
  • Figure 5 is a histogram illustrating the experimental results of delivery of a protein, horseradish peroxidase, across the blood-brain barrier in rat brains in the form of a conjugate with OX-26.
  • Figure 6 is a histogram illustrating the experimental results of delivering soluble CD4 to rat brain parenchyma using CD4 in the form of a conjugate with OX-26.
  • Figure 7 is a histogram illustrating the biodistribution of antibody 128.1 and control IgG in a cynomolgous monkey.
  • Figure 8 is a flow diagram of the general strategy for the expression of immunoglobulin variable region genes obtained by PCR.
  • Figure 9 illustrates the primers used for variable region amplification, both for first cloning and sequencing the V region and then for cloning into the final expression vector.
  • Figure 10 illustrates the cloning of the 128.1 heavy chain variable region.
  • Figure 11 is the antibody coding sequence of heavy chain expression vector pAH4602 containing the 7 -1 isotype constant region.
  • Figure 12 illustrates the cloning of the 128.1 light chain variable region.
  • Figure 13 is the antibody coding sequence of light chain expression vector pAG4611.
  • Figure 14 illustrates the plasmid map of the heavy chain expression vector pAH4625 containing the 7 -2 isotype.
  • Figure 15 illustrates the plasmid map of the heavy chain expression vector pAH4807 containing the 7 -3 isotype.
  • Figure 16 illustrates the plasmid map of the heavy chain expression vector pAH4808 containing the 7 -4 isotype.
  • Figure 17 is the antibody coding sequence of heavy chain expression vector pAH4625 containing the 7 -2 isotype constant region.
  • Figure 18 is the antibody coding sequence of heavy chain expression vector pAH4807 containing the 7 -3 isotype constant region.
  • Figure 19 is the antibody coding sequence of heavy chain expression vector pAH4808 containing the 7 -4 isotype constant region.
  • the method for delivering a neuropharmaceutical agent across the blood brain barrier to the brain of a host comprises administering to the host a therapeutically effective amount of an antibody- neuropharmaceutical agent conjugate wherein the antibody is reactive with a transferrin receptor present on a brain capillary endothelial cell.
  • the method is conducted under conditions whereby the antibody binds to the transferrin receptor on the brain capillary endothelial cell and the neuropharm ⁇ aceutical agent is transferred across the blood brain barrier in a pharmaceutically active form.
  • the host can be an animal susceptible to a neurological disorder (i.e., an animal having a brain) .
  • a neurological disorder i.e., an animal having a brain
  • Examples of hosts include mammals such as humans, domestic animals (e.g., dog, cat, cow or horse) , mice and rats.
  • the neuropharmaceutical agent can be an agent having a therapeutic or prophylactic effect on a neurological disorder or any condition which affects biological functioning of the central nervous system.
  • neurological disorders include cancer (e.g. brain tumors) , Autoimmune Deficiency Syndrome (AIDS) , stroke, epilepsy, Parkinson's disease, multiple sclerosis, neurodegenerative disease, trauma, depression, Alzheimer's disease, migraine, pain, or a seizure disorder.
  • Classes of neuropharmaceutical agents which can be used in this invention include proteins, antibiotics, adrenergic agents, anticonvulsants, small molecules, nucleotide analogs, che otherapeutic agents, anti-trauma agents, peptides and other classes of agents used to treat or prevent a neurological disorder.
  • proteins include CD4 (including soluble portions thereof) , growth factors (e.g. nerve growth factor and interferon) , dopamine decarboxylase and tricosanthin.
  • antibiotics include amphotericin B, gentamycin sulfate, and pyrimethamine.
  • adrenergic agents include dopamine and atenolol.
  • chemotherapeutic agents include adriamycin, methotrexate, cyclophosphamide, etoposide, and carboplatin.
  • An example of an anticonvulsant which can be used is valproate and an anti-trauma agent which can be used is superoxide dismutase.
  • peptides would be somatostatin analogues and enkephalinase inhibitors.
  • Nucleotide analogs which can be used include azido thymidine (hereinafter AZT) , dideoxy Inosine (ddl) and dideoxy cytodine (ddc) .
  • the antibody which is reactive with a transferrin receptor present on a brain capillary endothelial cell, may also be conjugated to a diagnostic agent.
  • the neuropharmaceutical agent of the neuropharmaceutical agent - anti-transferrin receptor conjugate has been replaced with a diagnostic agent.
  • the diagnostic agent is then delivered across the blood brain barrier to the brain of the host.
  • the diagnostic agent is then detected as indicative of the presence of a physiological condition for which the diagnostic agent is intended.
  • the diagnostic agent may be an antibody to amyloid plaques.
  • this diagnostic agent antibody When conjugated to an antibody reactive with a transferrin receptor present on a brain capillary endothelial cell, this diagnostic agent antibody can be transferred across the blood brain barrier and can then subsequently immunoreact with amyloid plaques. Such an immunoreaction is indicative of Alzheimer's Disease.
  • Serum transferrin is a monomeric glycoprotein with a molecular weight of 80,000 daltons that binds iron in the circulation and transports it to the various tissues(Aisen et al. (1980) Ann. Rev. Biochem. 49:357-393; MacGillivray et al. (1981) J. Biol. Chem. 258:3543-3553).
  • the uptake of iron by individual cells is mediated by the transferrin receptor, an integral membrane glycoprotein consisting of two identical 95,000 dalton subunits that are linked by a disulfide bond.
  • the number of receptors on the surface of a cell appears to correlate with cellular proliferation, with the highest number being on actively growing cells and the lowest being on resting and terminally differentiated cells.
  • Jeffries et al (Nature Vol. 312 (November 1984) pp. 167-168) used monoclonal antibodies to show that brain capillary endothelial cells have a high density of transferrin receptors on their cell surface.
  • Antibodies which can be used within this invention are reactive with a transferrin receptor.
  • the term antibody is intended to encompass both polyclonal and monoclonal antibodies.
  • the preferred antibody is a monoclonal antibody reactive with a transferrin receptor.
  • the term antibody is also intended to encompass mixtures of more than one antibody reactive with a transferrin receptor (e.g., a cocktail of different types of monoclonal antibodies reactive with a transferrin receptor) .
  • the term antibody is further intended to encompass whole antibodies, biologically functional fragments thereof, and chimeric antibodies comprising portions from more than one species, bifunctional antibodies, etc.
  • Biologically functional antibody fragments which can be used are those fragments sufficient for binding of the antibody fragment to the transferrin receptor to occur.
  • the antibodies, chimeric or otherwise, are not to be considered as being restricted to a specific isotype. Any of the antibody isotypes are within the present invention. For example, antibodies with identical light chains but different heavy chains are intended. In addition, mutations of certain regions of the antibodies, e.g., in the chains, are also intended. These mutations, particularly point mutations, may occur anywhere provided functionality of the antibodies as reactive with a transferrin receptor is still maintained.
  • the chimeric antibodies can comprise portions derived from two different species (e.g., human constant region and murine variable or binding region) .
  • the portions derived from two different species can be joined together chemically by conventional techniques or can be prepared as single contiguous proteins using genetic engineering techniques.
  • DNA encoding the proteins of both the light chain and heavy chain portions of the chimeric antibody can be expressed as contiguous proteins.
  • variable region of functional antibodies is that portion of the antibody that immunologically reacts with the transferrin receptor antigen. Both the heavy chain and light chain of antibodies contribute to the variable region.
  • the DNA encoding the variable region has two portions: a polynucleotide sequence encoding the variable region heavy chain and a polynucleotide sequence encoding the variable region light chain.
  • the primed variable regions can then be cloned into vectors which contain the DNA encoding the constant region of antibodies.
  • a particularly useful vector is one which contains DNA encoding the constant region of human antibodies that has been designed to also express immunoglobulin variable regions from other sources.
  • the DNA encoding the constant region is usually from a separate source than the one whose DNA encodes the variable region.
  • different animals from the same species may be the sources of the DNA encoding the variable region and the constant region, the usual situation is where the animal species are different (e.g., human constant region and murine variable region) .
  • chimeric antibodies can be expressed from such vectors.
  • transferrin receptor is intended to encompass the entire receptor or portions thereof. Portions of the transferrin receptor include those portions sufficient for binding of the receptor to an anti-transferrin receptor antibody to occur.
  • Monoclonal antibodies reactive with at least a portion of the transferrin receptor can be obtained (e.g., OX-26, B3/25 (Omary et al. (1980) Nature 28i6,888-891) , T56/14 (Gatter et al. (1983) J. Clin. Path. 36 539-545; Jefferies et al. Immunology (1985) 54:333-341), OKT-9 (Sutherland et al. (1981) Proc. Natl. Acad. Sci. USA 78:4515-4519) , L5.1 (Rovera, C. (1982) Blood 59:671-678) , 5E-9 (Haynes et al. (1981) J. Immunol.
  • RI7 217 (Trowbridge et al. Proc. Natl. Acad. Sci. USA 78:3039 (1981) and T58/30 (Omary et al. cited supra)or can be produced using conventional somatic cell hybridization techniques (Kohler and Milstein (1975) Nature 256, 495-497).
  • a crude or purified protein or peptide comprising at least a portion of the transferrin receptor can be used as the immunogen.
  • An animal is vaccinated with the immunogen to obtain an anti-transferrin receptor antibody-producing spleen cells.
  • the species of animal immunized will vary depending on the species of monoclonal antibody desired.
  • the antibody produc ⁇ ing cell is fused with an immortalizing cell (e.g. myeloma cell) to create a hybridoma capable of secreting anti-transferrin receptor antibodies.
  • an immortalizing cell e.g. myeloma cell
  • the unfused residual antibody-producing cells and immortalizing cells are eliminated.
  • Hybridomas producing the anti-transferrin receptor antibodies are selected using conventional techniques and the selected anti-tranferrin receptor antibody producing hybridomas are cloned and cultured.
  • Polyclonal antibodies can be prepared by immunizing an animal with a crude or purified protein or peptide comprising at least a portion of a transferrin receptor. The animal is maintained under conditions whereby antibodies reactive with a transferrin receptor are produced. Blood is collected from the animal upon reaching a desired titer of antibodies. The serum containing the polyclonal antibodies (antisera) is separated from the other blood components. The polyclonal antibody-containing serum can optionally be further separated into fractions of particular types of antibodies (e.g. IgG, IgM) .
  • the neuropharmaceutical agent can be linked to the antibody using standard chemical conjugation techniques. Generally, the link is made via an amine or a sulfhydryl group.
  • the link can be a cleavable link or non-cleavable link depending upon whether the neuropharmaceutical agent is more effective when released in its native form or whether the pharmaceutical activity of the agent can be maintained while linked to the antibody.
  • the determination of whether to use a cleavable or non-cleavable linker can be made without undue experimentation by measuring the activity of the drug in both native and linked forms or for some drugs can be determined based on known activities of the drug in both the native and linked form.
  • antibody-protein or antibody peptide conjugates can be constructed using noncleavable linkers.
  • proteins or peptides include CD4, superoxide dismutase, interferon, nerve growth factor, tricosanthin, dopamine decarboxylase, somatostatin analogues and enkephalinase inhibitors.
  • Terms such as "CD4" are used herein to include modified versions of the natural molecule, such as soluble CD4, truncated CD4, etc.
  • non-cleavable linker systems which can be used in this invention include the carbodiimide (EDC) , the sulfhydryl-maleimide, the N-succinimidyl-3-(2-pyridyldithio) propionate (SPDP; Pharmacia) , and the periodate systems.
  • EDC carbodiimide
  • SPDP N-succinimidyl-3-(2-pyridyldithio) propionate
  • SPDP N-succinimidyl-3-(2-pyridyldithio) propionate
  • the periodate systems a water soluble carbodiimide reacts with carboxylic acid groups on proteins and activates the carboxyl group. The carboxyl group is coupled to an amino group of the second protein. The result of this reaction is a noncleavable amide bond between two proteins.
  • a sulfhydryl group is introduced onto an amine group of one of the proteins using a compound such as Traut's reagent.
  • the other protein is reacted with an NHS ester (such as gamma-malei idobutyric acid NHS ester (GMBS)) to form a maleimide derivative that is reactive with sulfhydryl groups.
  • NHS ester such as gamma-malei idobutyric acid NHS ester (GMBS)
  • GMBS gamma-malei idobutyric acid NHS ester
  • SPDP is a heterobifunctional crosslinking reagent that introduces thiol-reactive groups into either the monoclonal antibody or the neuropharma ⁇ ceutical agent.
  • the thiol-reactive group reacts with a free sulfhydryl group forming a disulfide bond.
  • Periodate coupling requires the presence of oligosaccharide groups on either the carrier or the protein to be delivered. If these groups are available on the protein to be delivered (as in the case of horseradish peroxidase (HRP) ) , an active aldehyde is formed on the protein to be delivered which can react with an amino group on the carrier. It is also possible to form active aldehyde groups from the carbohydrate groups present on antibody molecules.
  • the periodate oxidized antibody can be reacted with a hydrazide derivative of a protein to be delivered which will also yield a stable conjugate.
  • Cleavable linkers can be used to link neuro ⁇ pharmaceutical agents which are to be deposited in the brain or when a non-cleavable linker alters the activity of a neuropharmaceutical agent.
  • cleavable linkers include the acid labile linkers described in copending patent application Serial No. 07/308,960 filed February 6, 1989, the contents of which are hereby incorporated by reference.
  • Acid labile linkers include cis-aconitic acid, cis-carboxylic alkadienes, cis-carboxylic alkatrienes, and poly-maleic anhydrides.
  • Other cleavable linkers are linkers capable of attaching to primary alcohol groups.
  • the noncleavable linkers used generally to link proteins to the antibody can also be used to link other neuropharmaceutical agents to the antibody.
  • the antibody-neuropharmaceutical agent conjugates can be administered orally, by subcutaneous or other injection, intravenously, intramuscularly, parenternally, transdermally, nasally or rectally.
  • the form in which the conjugate is administered e.g., capsule, tablet, solution, emulsion
  • a therapeutically effective amount of an antibody-neuropharmaceutical agent conjugate is that amount necessary to significantly reduce or eliminate symptoms associated with a particular neurological disorder.
  • the therapeutically effective amount will be determined on an individual basis ' and will be based, at least in part, on consideration of the individuals's size, the severity of symptoms to be treated, the result sought, the specific antibody, etc. Thus, the therapeutically effective amount can be determined by one of ordinary skill in the art employing such factors and using no more than routine experimentation.
  • any protein which interacts with the extracellular domain of the transferrin receptor could potentially serve as a vehicle for the delivery of drugs across the blood-brain barrier.
  • any ligand which binds to the transferrin receptors could potentially be employed.
  • a procedure for producing chimeric antibodies reactive with a transferrin receptor may be performed as follows: cDNA is synthesized from mRNA purified from a small number of cells producing the antibody of interest.
  • a PCR reaction is performed in order to obtain the antibody heavy and light chain variable regions which are then cloned and sequenced. After a second PCR reaction to modify the ends of these regions to make them compatible with the expression cassettes, they are cloned into novel expression vectors which contain human constant regions, immunoglobulin promoter and enhancers, and selection markers.
  • a murine heavy chain promoter has been provided with restriction sites so that the leader sequences primed and expanded can be directly cloned into a functional promoter. Restriction sites have also been provided for the direct cloning of the 3' end of the variable region into a constant region.
  • a novel restriction site has been engineered into the CHI domain of the human I heavy chain gene.
  • VH can then be joined at this site to provide a complete heavy chain protein.
  • a restriction site has been engineered just 3' of the splice site so that the cloned VL will then splice the kappa to produce a complete K light chain protein.
  • the final constructs are then transfected into non-producer hybridoma cell lines as SP2/0 or P3.X63.Ag8653 and the supernatants tested for antibody production ( Figure 8) .
  • Hybridoma cell lines which produce B3/25 and T58/30 antibodies were obtained from the American Type Culture Collection (ATTC) in Rockville, Maryland, and grown in DMEM medium supplemented with 2.0 mM glutamine, 10.0 mM HEPES (pH 7.2), 100 ⁇ non- essential amino acids and 10% heat-inactivated fetal calf serum. The hybridoma cultures were scaled-up in
  • Antibody which had specifically bound to the fixed cells was detected using a biotin-labeled polyclonal goat-anti-mouse IgG antisera followed by a biotinylated horseradish peroxidase (HRP) /avidin mixture (Avidin Biotin Complex technique) . Positive wells were determined using a Titertek Multiscan Enzyme Linked Immunosorbent Assay (ELISA) plate reader. The results showed that both antibodies bind to human brain capillary endothelial cells with the T58/30 antibody exhibiting a higher level of binding.
  • HRP horseradish peroxidase
  • ELISA Titertek Multiscan Enzyme Linked Immunosorbent Assay
  • the slides containing the human brain sections were allowed to come to room temperature prior to use. The sections were then rehydrated in DPBS and incubated in methanol containing 0.3% H»0 to block endogenous peroxidate activity. The sections were blocked for fifteen minutes in a solution containing 0.2% non-fat dry milk and 0.2% methylmannopyrano- side. B3/25 and T58/30 antibodies, purified as discussed above, were applied to the sections at a concentration of 5-50 ⁇ g/ml and incubated at room temperature for one to two hours. Antibody that specifically bound to the tissue was detected using the Avidin-Biotin Complex (ABC) technique as described above for the ELISA assay. Staining of capillaries in the human brain sections was observed with both the B3/25 and T58/30 antibodies. The T58/30 antibody also displayed some binding to the white matter of the brain cortex.
  • ABSC Avidin-Biotin Complex
  • the OX-26 murine antibody which recognizes the rat transferrin receptor, has been shown in vivo to bind to brain capillary endothelial cells (Jeffries et al. , cited supra) .
  • the murine hybridoma line which produces the OX-26 murine antibody was obtained and the hybridoma cell line was grown in RPMI 1640 medium supplemented with 2.0 mM glutamine and 10% heat-inactivated fetal calf serum.
  • the OX-26 antibody was purified using the affinity chroma ⁇ tography technique described in Example 1.
  • the purified antibody was tested i i vitro as described for the anti-human transferrin receptor antibodies in Example 1 to determine whether it would bind to brain capillaries in fresh frozen, acetone-fixed rat brain sections. The results showed that the OX-26 anti-transferrin receptor antibody did bind to capillaries in rat brain sections In vitro.
  • the rat anti-transferrin receptor antibody OX-26 was tested jLn vivo by injecting purified antibody (purification as described in Example 1) into female Sprague-Dawley rats (100-150 g ) via the tail vein. Prior to injection, the rats were anesthetized with halothane. The samples, ranging from 2.0 mg to 0.05 mg of antibody/rat were injected into the tail vein in 400 ⁇ l aliquots. All doses were tested in duplicate animals. One hour post-injection, the animals were sacrificed and perfused through the heart with DPBS to clear the blood from the organs. Immediately after the perfusion was completed, the brain was removed and quick frozen in liquid nitrogen.
  • the frozen brain was then sectioned (30-50 ⁇ m) on a cryostat and the sections placed on glass microscope slides.
  • the brain sections were air dried at room temperature one to two hours before fixation in acetone (10 minutes at room temperature) . After this treatment the sections could be stored at -20°C.
  • the OX-26 antibody was localized in the brain sections using immunohistochemistry as-described above for the in vitro experiments in Example 1. The addition of the primary antibody was unnecessary in that it is present in the brain sections.
  • the results indicated that the OX-26 antibody binds to rat brain capillary endothelial cells and that doses of as little as 50 ⁇ g result in detectable levels of antibody in the brain using the methods described herein.
  • a non-specific antibody of the same subclass as OX-26 (IgG 2a) was also tested in vivo to show that the binding of OX-26 to rat brain endothelial cells that has been observed is specific to the OX-26 antibody.
  • 0.5 mg of the control antibody was injected per rat as described above. The results indicate that the staining pattern observed with the OX-26 antibody is specific to that antibody.
  • the time frame in which this binding occurred was determined.
  • brain sections taken from animals sacrificed 5 minutes, 15 minutes, 1 hour, 2 hours, 4 hours, 8 hours and 24 hours post-injection were examined for the presence of OX-26 antibody. All doses were administered in 400 ⁇ l aliquots and each time point was tested in duplicate animals. Samples were injected and the rats were processed at the various times post- injection as described above in the dose range section.
  • the OX-26 antibody can be detected in or on the rat brain capillary endothelial cells as early as five minutes and as late as 24 hours post-injection. At 4 and 8 hours post-injection, the staining pattern of the antibody is very punctate suggesting that the antibody has accumulated in vesicular compartments either in endothelial or perivascular cells.
  • EXAMPLE 4- The Use of a Conjugate of OX-26 Murine Monoclonal Antibody for Tranferring Horseradish Peroxidase Across the Blood Brain Barrier
  • Horseradish Peroxidase (HRP; 40 kD) was chosen as a compound to be delivered to the brain because it is similar in size to several therapeutic agents and it can be easily detected in the brain using an enzymatic assay.
  • HRP was conjugated to the OX-26 antibody using a non-cleavable periodate linkage and the ability of the antibody to function as a carrier of compounds to the brain was examined. The antibody conjugate was tested _in vivo to determine if the antibody could deliver HRP to the brain.
  • the HRP (10 mg) was dissolved in 2.5 ml deionized water, 0.1 M sodium periodate (160 ⁇ l) was added and the mixture was incubated for five minutes at room temperature. Ethylene glycol (250 ⁇ l) was added to the HRP solution followed by an additional five minute incubation. This solution was then dialyzed overnight against 1.0 mM sodium acetate buffer (pH 4.4). To the dialyzed OX-26 antibody (2.0 ml, 5.08 mg/ml) was added 200 ⁇ l of 1.0 M sodium bicarbonate buffer, pH 9.5 and 1.25 ml of the dialyzed HRP solution.
  • Example 3 A time course experiment identical to that described in Example 3 was performed using the antibody-HRP conjugate.
  • the antibody-HRP conjugate (0.5 mg) was injected in a 400 ⁇ l aliquot/rat.
  • the animals were sacrificed at the various times post-injection and the brains processed as described above in Example 3.
  • the antibody HRP conjugate was localized in the brain either by staining for antibody immunohistochemically as described in Example 1 or by directly staining the brain sections for the presence of HRP.
  • the slides were first allowed to come to room temperature before incubating in methanol for thirty minutes.
  • the brain sections were then washed in DPBS and reacted with 3,3'-diamino benzidine (DAB), the substrate for HRP.
  • DAB 3,3'-diamino benzidine
  • a non-cleavable linker system similar to that used in Example 4 was used to couple the chemotherapeutic drug adriamycin to the OX-26 antibody.
  • the availability of antibodies that can detect adriamycin as well as the system previously described in Example 1 for detecting the antibody carrier allowed the use of immunohistochemical tech ⁇ niques for monitoring the localization of the antibody carrier as well as the delivery of adriamycin to the brain.
  • the drug (10 mg in 0.5 ml DPBS) was oxidized by the addition of 200 ⁇ l of 0.1 M sodium periodate. This mixture was incubated for one hour at room temperature in the dark. The reaction was quenched by the addition of 200 ⁇ l of ethylene glycol followed by a five minute incubation.
  • the OX-26 antibody (5.0 mg in 0.5 ml of carbonate buffer (pH 9.5)) was added to the oxidized adriamycin and incubated at room temperature for one hour. Sodium borohydride (100 ⁇ l of 10 mg/ml) was added and the mixture was incubated for an additional two hours at room temperature.
  • the free adriamycin was separated from the OX-26 antibody-adriamycin conjugate by chromatography on a PD-10 column.
  • the adriamycin/OX-26 antibody ratio within the conjugate was 2/1. for this particular batch of conjugate.
  • the effectiveness of the OX-26 antibody as a carrier for delivering adriamycin to the brain was determined by administering 0.5 mg of the antibody-adriamycin conjugate in a 400 ⁇ l aliquot per rat by injection via the tail vein. One hour post-injection, the rat was sacrificed and the brain processed as described in Example 1. All injections were performed in duplicate. As a control, 400 ⁇ g of free adriamycin in a 400 ⁇ l aliquot was also injected into a rat. Immunohistochemistry was used to detect both the carrier OX-26 antibody and the adriamycin in the rat brain sections.
  • polyclonal rabbit anti-adria ycin antisera was applied to the sections followed by a biotinylated goat anti-rabbit IgG antisera. This was then followed by the addition of a biotinylated HRP/avidin mixture and enzymatic detection of HRP.
  • adriamycin-OX-26 conjugate coupled via a carbodiimide linkage was also synthesized (drug/ antibody ratio of 10/1) and tested _in vivo.
  • the results of this experiment were essentially identical to that obtained with the periodate-linked antibody-drug conjugate.
  • staining for the antibody carrier was quite strong and was visualized in the capillaries in all areas of the brain. This staining was evenly distributed along the capillaries. Staining for adriamycin was less intense but again was seen in capillaries throughout the brain. Some punctate staining was observed which suggests accumulation in pericytes which lie on the brain side of the blood-brain barrier.
  • EXAMPLE 6- ⁇ n Vivo Delivery of Methotrexate to the Brain by Murine Monoclonal Antibody OX-26.
  • a noncleavable carbodiimide linkage was used to couple methotrexate to the OX-26 murine monoclonal antibody.
  • a system analogous to that described in Example 5 was used to monitor the delivery of both the methotrexate and the carrier antibody to the brain capillary endothelial cells.
  • Methotrexate was coupled to murine monoclonal antibody OX-26 via its active ester. Briefly, 81 mg (0.178 mM) of methotrexate (Aldrich) was stirred with 21 mg (0.182 mM) of N-hydroxysuccinimide (Aldrich) in 3 ml of dimethylformamide (DMF) at 4°C. Ethyl-3-dimethylaminopropyl-carbodiimide (180 mg;EDC;0.52mM) was added to this solution and the reaction mixture was stirred overnight.
  • DMF dimethylformamide
  • the crude ester was purified from the reaction by-products by flash chromatography over silica gel.60 (Merck) using a solution of 10% methanol in chloroform as an eluant.
  • the purified active ester fractions were pooled and concentrated to dryness.
  • the ability of the OX-26 monoclonal antibody to deliver methotrexate to the rat brain capillary endothelial cells was tested _in vivo by injecting 0.2 mg of conjugate (in 400 ⁇ l) into each of two rats via the tail vein. The animals were sacrificed one hour post-injection and the brains processed for immunohistochemistry as described in Example 1. To detect methotrexate in the brain, a rabbit antisera raised against methotrexate was used as the primary antibody. A biotinylated goat-anti-rabbit antisera in conjunction with a mixture of biotinylated HRP and avidin was then used to visualize methotrexate in the rat brain. The carrier antibody was detected as described previously.
  • methotrexate in the form of a conjugate with OX-26 does accumulate along or in the capillary endothelial cells of the brain.
  • the staining observed for methotrexate is comparable in intensity to that seen for the carrier.
  • the staining appears to be in all areas of the brain and is evenly distributed along the capillaries.
  • EXAMPLE 7- Antibody Derivatives The Fc portion of the OX-26 murine monoclonal antibody was removed to determine whether this would alter its localization to or uptake by the rat brain capillary endothelial cells.
  • F(ab) fragments of OX-26 were produced from intact IgG's via digestion with pepsin. A kit available from Pierce Chemical Co. contains the reagents and protocols for cleaving the antibody to obtain the fragments .
  • the F(ab') repeat fragment (0.2 mg doses) in 400 ⁇ l aliquots were injected into rats via the tail vein. A time course experiment identical to that done with the intact antibody (Example 2) was then performed.
  • F(ab')_ fragment was detected immunohistochemically using a goat anti-mouse F(ab')_ antisera followed by a biotinylated rabbit anti-goat IgG antisera. A biotinylated HRP/avidin mixture was added and the antibody complex was visualized using an HRP enzymatic assay. The results indicate that the F(ab) fragment of the OX-26 antibody binds to the capillary endothelial cells of the rat brain.
  • radiolabelled compounds were injected as a 400 ⁇ l bolus into the tail vein of female Sprague-Dawley rats (100-125 gms) under Halothane anesthesia and the animals were sacrificed at the appropriate time post-injection using a lethal dose of anesthetic.
  • a 3H-labelled IgC2a control antibody was co- jected with the 14C-labelled OX-26 to serve as a control for non-specific radioactivity in the brain due to residual blood.
  • mice were sacrificed and the brains were removed immedicately and homogenized in 5 ml of 0.5% sodium dodecysulfate using an Omni-mixer. An aliquot of the homogenate was incubated overnight with 2 ml of Soluene 350 tissue solubilizer prior to liquid scintillation counting. All data were collected as disintegrations per minute (dpm) . Blood samples were centrifuged to pellet red blood cells (which do not display significant binding of radiolabelled materials) and the radioactivity in an aliquot of serum determined using liquid scintillation counting.
  • dpm disintegrations per minute
  • the amount of antibody associated with the brain was determined at various times post-injection to examine the pharmacokinetics of brain uptake.
  • the amount of labelled antibody in the blood was measured so that the rate of clearance from the bloodstream could be determined.
  • This information was also used to calculate the amount of radioactivity in the brain due to blood contamination, which was then subtracted from the total to give the amount of antibody that is specifically associated with the brain.
  • the amount of radioactivity associated with the brain decreased steadily from 4 to 48 hours post-injection, at which point it leveled off at approximately 0.3% of the injected dose.
  • the accumulation of OX-26 in the brain was significantly reduced by the addition of unlabelled monoclonal antibody (0.5 or 2.0 mg in the bolus injection) .
  • unlabelled monoclonal antibody 0.5 or 2.0 mg in the bolus injection
  • control antibody did not accumulate in the brain and represented the blood contamination of the brain.
  • the blood level of OX-26 dropped quite dramatically immediately after injection such that by 1 hour post—injection, the percent of injected dose in 55 ⁇ l of blood (the volume of blood associated with the brain) was approximately 0.16% as illustrated in
  • Figure 1 This corresponds to a value of approximately 20% of the injected dose in the total blood volume of the rat.
  • Extraction of total IgG from serum followed by polyacrylamide gel electro- phoresis (PAGE) and autoradiography did not reveal detectable levels of OX-26 degradation indicating that the antibody remains intact in the blood as long as 48 hours after injection.
  • the radiolabelled compounds were injected as a 400 ⁇ l bolus into the tail vein of femals Sprague-Dawley rats (100-125 gm) under Halothane anesthesia and the animals were sacrificed at the appropriate time post-injection using a lethal dose of anesthetic.
  • 3H-labelled IgG 2a control antibody was co-injected with the 14C-labelled OX-26 to serve as a control for non-specific radioactivity in the brain due to residual blood. After sacrifice, the brains were removed and kept on ice. After an initial mincing, the brains were homogenized by hand (8-10 strokes) in
  • a comparison of the relative amounts of radioactivity in the different brain fractions as a function of time indicates whether transcytosis of the labelled antibody has occurred.
  • the amount of 0X-26 in total brain homogenate, the brain parenchyma fraction and the brain capillary fraction at an early time (30 minutes) and a later time (24 hours) post-injection is illustrated in Figure 2.
  • the distribution is reversed and the majority of the radioactivity (0.36% ID) is in the parenchymal fraction as compared to the capillary fraction (0.12% ID) .
  • the redistribution of the radiolabelled OX-26 from the capillary fraction to the parenchyma fraction is consistent with the time dependent migration of the anti-transferrin receptor antibody across the blood-brain barrier.
  • N 3 rats per time point
  • the linker was synthesized as follows. Succinic anhydride was used to acylate the AZT by reacting equimolar amounts of these two compounds for 3 hours at room temperature under argon in the presence of dimethylaminopyridine and sodium bisulfate in freshly distilled pyridine. The product was isolated by chromatography on a DEAE sephadex A50 column run with a triethylammonium bicarbonate buffer. The succinate derivative of AZT was activated at the carboxyl group as the NHS ester by reaction with equimolar amounts of N-hydroxysuccinimide and dicyclohexylcarbodiimide
  • the product was purified by flash charomatography on silica gel.
  • the resulting NHS-ester of AZT-succinate was used to acylate amine groups on OX-26, resulting in an AZT-OX-26 conjugate.
  • AZT-NHS ester was reacted with OX-26 in HEPES buffer overnight at 4°C.
  • the antibody-drug conjugate was isolated from free drug on a PD-10 column. The molar ratio of drug to antibody was 7:1.
  • Example 3 performed with a H-labelled OX-26-HRP conjugate that was prepared using a non-cleavable periodate linkage as described in Example 4.
  • the tritium label was distributed between the antibody and-the HRP portion of the conjugate.
  • the majority of the radioactivity associated with the brain is in the capillary fraction as illustrated in
  • the distribution of radioactivity associated with the brain changed such that the majority is in the fraction which represents the brain parenchyma.
  • essentially all of the 3 H-labelled OX-26-HRP conjugate is in the parenchyma fraction of the brain indicating that the material has crossed the blood-brain barrier. Similar results were obtained in experiments in which only the HRP portion of the conjugate was radiolabelled.
  • the percent of injected dose of the OX-26-HRP conjugate that reaches the brain is somewhat lower than that for antibody alone or the OX-26-HRP conjugate.
  • the linkage between the proteins was achieved by first introducing a sulfhydryl group onto CD4 using SATA (N-Succinimidyl S-acetylthioacetate) , a commerically available compound.
  • SATA N-Succinimidyl S-acetylthioacetate
  • a hydrizid derivative of SDPD another commercial cross-linking agent, was attached to OX-26 via carbohydrate groups on the antibody. Reaction of the two modified proteins gives rise to a disulfide-linked conjugate.
  • SATA N-succinimidyl S-acetylthioacetate
  • a collection of 32 murine monoclonal antibodies which recognize various epitopes on the human transferrin receptor were examined for reactivity with brain capillary endothelial cells in sections from human, monkey (cynomolgous) , rat and rabbit brain samples by the immunohistochemical methods described in Example 1. These antibodies were obtained from Dr. Ian Trowbridge of the Salk Institute, LaJolla, CA. All 32 antibodies displayed some reactivity with human brain endothelial cells. Two antibodies reacted very weakly with rabbit brain capillaries and none reacted with rat. While 21 of the antibodies reacted with monkey brain capillaries, only 2 displayed strong reactivity comparable to that seen with human brain capillaries. These 2 antibodies are herewithin referred to as 128.1 and Z35.2.
  • oligo dT primer For light chain V region amplifications, an oligo dT primer was used, whereas for the amplification of heavy chain V regions a 7 CHI antisense primer, containing an Xbal site (underlined in Table 1) , with degeneracies introduced so that it will prime all isotypes of murine heavy chains except 7 3 was used
  • first strand cDNA buffer 50 mM Tris pH 8.3, 50 mM KCl, 10 mM MgCl 2 , 1 mM DTT, 1 M EDTA, 0.5 mM spermidine
  • RNAse inhibitor Promega
  • 2 ⁇ l of 10 mM dNTP's and 2 ⁇ l of prediluted 1:10 Promega AMV Reverse Transcriptase were added and the reaction incubated for 1 hour at 42°C.
  • the cDNA was kept at -20°C until used for PCR.
  • a first PCR reaction was performed in order to amplify the variable regions and determine their sequence.
  • the PCR primers were designed to hybridize to the leader sequence (5' primer) and to the constant region immediately downstream of the V-J region (3' primer).
  • oligonucleotides were synthesized in an Applied Biosystem 391 DNA Synthesizer, eluted without purification, diluted to 20 ⁇ M and kept at 4°C.
  • All primers were designed with a restriction site with three additional bases upstream to protect the site and facilitate enzyme digestion.
  • the sites were chosen to make possible the cloning of the PCR product into a subcloning vector and into the final expression cassett vectors.
  • the primers For the leader region, the primers contain a ribosome recognition site (Kozak's sequence CACC; Kozak M. 1981, Nucl. Acid. Res., 9:20, 5233-5252) 5' of the start codon, and an EcoR V site (underlined in Tables 2 and 3) protected by three 5' G's.
  • a set of 4 universal 5' sense primers was used simultaneously in the light variable region amplification, and a set of 3 universal 5' sense primers in the case of heavy variable regions (Coloma et al. 1991, Biotechniques 11,2,152-156). An equimolar amount of each primer was used in the PCR reaction.
  • primers contain degeneracies in order to hybridize with all the families of murine leader sequences reported in Rabat's database. (Kabat E. 1987, Sequences of Proteins of Immunological Interest, NIH) .
  • the 3' primers were designed in the constant region 20 bases downstream of the V-J region and contain an Xbal site (underlined in Tables 2 and 3) for subcloning purposes (Tables 2 and 3) .
  • Table 2 PRIMERS FOR MURINE HEAVY CHAIN VARIABLE REGION AMPLIFICATION. (Degeneracies at a single position are shown in parenthesis.)
  • the primers for the second PCR reaction have the actual sequence of the V-J regions, determined by sequencing of the subcloned products (Table 4) .
  • These primers have a Nhe I site in the case of the VH primer and Sal I for the VL primer, which permits the cloning into the expression vectors. (The restriction enzyme sites are underlined in Table 4) .
  • the Nhe I site in the 3' primer for the VH allows the direct ligation of the VH-J region to the first two amino acids of the CHI of the I constant region.
  • the VL 3' primer has a donor splice sequence before its Sal I site which is necessary to splice the VL to C K in the expression vector.
  • Primer designed to hybridize to amino acids 111-113 in J4 region of 128.1 heavy chain V region. It includes a Nhe I site for cloning into the expression vector (links J4 to CHI) and Sal I for subcloning (upstream Nhe I) .
  • Primer designed to hybridize to amino acids 101-107 in J4 region of 128.1 light chain V region. It includes a donor splicing sequence which is highlighted.
  • PCR reactions were performed in a volume of 100 ⁇ l with the following final conditions: 2 ⁇ l of cDNA, 0.5 ⁇ l Taq polymerase (Cetus Corporation) , IX buffer (10 mM Tris pH8, 1.5 mM MgCl , 50 mM KCl, 100 ⁇ g BSA) , 200 ⁇ M each dNTP, l ⁇ M of each primer and 50 ⁇ l of mineral oil.
  • PCR was carried out for 30 cycles in a PTC 100 Thermal Controller (M.J. Research Inc.) with 1 min. denaturing (94°C) , l min. annealing (55°C) , 1.5 min. extension (72°C) , and a final extension of 10 min.
  • the size of the PCR products was verified by agarose gel electrophoresis in a 2% TAE gel stained with ethidium bromide. The correct products were approximately 380 base pairs for the light chain and 420 base pairs for the heavy chain variable region.
  • Dideoxynucleotide chain termination sequencing was carried out using T7 DNA polymerase (Pharmacia, Uppsala, Sweden or Sequenase, US Biochemical Corp., Cleveland, Ohio) according to the manufacturer's protocol. Four independent clones from different PCR reactions were sequenced in both directions, to obtain the concensus sequence.
  • Ta b le 5 CO M P LETE SEQUENCE OF CHIMERIC 128.1 (Anti-Human Transferrin Receptor) LIGHT CHAIN VARIABLE REGION, MOU S E KAPPA SUBGROUP VI
  • Plasmid pAH4274 is the vector for expression of heavy chain variable regions obtained by PCR with leader/J region priming. V region cloning into this cassette is performed by a complete digestion of vector and product with EcoR V and Nhe I. This vector has a human 7 I constant region whose CHI is directly linked with the 3' end of the VH-J region by means of a Nhe I site.
  • This 11 kb vector contains an ampicillin resistance gene for procaryotic selection, a heavy chain immunoglobulin enhancer and a histidine (histidinol) selection marker for selection of transfectants (Hartman, S., R. Mulligan, Proc. Natl. Acad. Sci. 85, 8047-8051) ; transcription is from the VH promoter of the murine 27.44 gene.
  • HB101 competent cells were transformed and plated on LB plates with 50 ⁇ g/ml of ampicillin. Colonies were screened by colony hybridization with a 32P end labelled leader region oligonucleotide. Positive clones were restriction mapped and maxi plasmid preps prepared using the QIAGEN maxi prep kit (QIAGEN Inc., Studio
  • Plasmid pAG4270 is the expression vector for light chain variable regions obtained by PCR with leader/J region priming.
  • the 14 kb vector has an ampicillin resistance gene, a gpt (mycophenolic acid resistance) selected marker, an immunoglobulin H enhancer and an introl for V-Constant region splicing; transcription is from the murine VH promoter from the 27.44 gene.
  • SP2/0 cells were cotransfected by electroporation.
  • the transfected cells were plated into five 96
  • transfectants were biosynthetically
  • Clones with the highest production identified by ELISA were expanded to 5 ml petri dishes and removed from selection. 1x10 cells were pelleted at 220xg for 5 minutes at 4°C and washed twice with labelling medium (high glucose DME deficient in methionine:
  • Cells were pelleted and supernatants drawn off for immunoprecipitation of secreted IgG.
  • Cell pellets were lysed in NDET (1% NP-40, 0.4% deoxycholate, 66 mM EDTA, 10 mM Tris, pH 7.4), centrifuged, and the supernatants removed and incubated 1 hour at 4°C with rabbit anti-human IgG Fc polyclonal antiserum (5 ⁇ l/ml) .
  • NDET 1% NP-40, 0.4% deoxycholate, 66 mM EDTA, 10 mM Tris, pH 7.4
  • rabbit anti-human IgG Fc polyclonal antiserum 5 ⁇ l/ml
  • IgG Sorb was added and mixed by rotation at 4°C for
  • Protein-A bound IgG was washed by centrifuging through 1 ml 30% sucrose in 100 ⁇ l NDET
  • the resultant autoradiograms revealed the expected patterns for fully functional antibodies.
  • the secreted antibodies that were in the cell supernatant exhibited the expected molecular weight pattern of free light chain, light chain dimer and the tetramer formed from two light chains and two heavy chains for fully expressed and assembled functional antibodies.
  • the pattern for antibody parts in the cell cytoplasm was also as expected for fully expressed antibody constitutents.
  • EXAMPLE 16 Further Mouse/Human Chimeras of the Anti-Human Transferrin Receptor Antibody 128.1.
  • the initial cloning of the gene encoding the heavy chain of the murine monoclonal antibody 128.1, which binds the human transferrin receptor involved placing the sequences encoding the variable region of the heavy chain into an expression vector containing the human 71 constant region framework.
  • Antibody production by selected transfectants was assessed by ELISA.
  • Cells were diluted in fresh medium to a density of 10 cells/ml and 1 ml was aliquoted into each of 3 wells on a 24-well culture plate. The plates were then incubated for 24 hours at 37°C with 5% CO . The media was then collected from the wells and the cells and debris were spun down to give a clarified supernatant.
  • ELISA a 96-well microtiter dish was coated with a goat antisera against human IgG.
  • the plate was washed and a series of dilutions of both the cell supernatants and human IgG standard of known concentration were applied to the plate and incubated for 1 hour at room temperature. The plate was then washed and biotinylated goat antisera against human IgG was added, followed by a mixture of avidin and biotinylated horseradish peroxidase (HRP) . The amount of antibody present in the samples was then determined, based on the amount of substrate converted by the HRP.
  • HRP horseradish peroxidase
  • the average values from three experiments were 39, 21 and 24 ⁇ g/ml IgG/10 cells/24 hours, respectively, for the different clones.
  • One 7 -3 clone has been tested and it was found to produce approximately 1 ⁇ g/ml IgG/10 cells/24 hours.
  • Two different clones of the 7 -4 chimera have been tested and were found to produce 2.8 and 0.2 ng/ml IgG/10 cells/24 hours, respectively.

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Abstract

La présente invention concerne un procédé d'administration d'un agent diagnostique ou neuropharmaceutique à travers la barrière sang-humeur aqueuse vers le cerveau d'un hôte. Le procédé consiste à administrer à l'hôte une quantité thérapeutiquement efficace d'un conjugué agent diagnostique ou neuropharmaceutique-anticorps dans lequel l'anticorps réagit avec un récepteur de transférine et cet anticorps est une chimère entre la région variable d'une source animale et la région constante d'une source animale différente. D'autres aspects de cette invention décrivent un système d'apport comprenant un anticorps réagissant à un récepteur de transferine lié à un agent neuropharmaceutique ou diagnostique et des procédés de traitement d'hôte ayant une maladie associée à un trouble neurologique. Dans des modes de réalisation de la présente invention, l'anticorps qui réagit à un récepteur de transférine est un anticorps chimérique. Cet anticorps se compose d'une région variable, réagissant par immunologie avec le récepteur de transférine, qui est amené depuis une source animale et une région constante qui est dérivée d'une source animale autre que celle qui a constitué la région variable. Les anticorps chimériques de cette invention peuvent exister soit sous la forme d'entités isolées soit sous la forme de conjugués avec un agent neuropharmaceutique pour traverser la barrière sang-humeur aqueuse. Dans ce dernier mode, le conjugué d'agent neuropharmaceutique-anticorps chimérique forme un système d'apport permettant d'administrer l'agent neuropharmaceutique à travers la barrière sang-humeur aqueuse.
EP93900677A 1991-11-26 1992-11-24 Procede de preparation de conjugues d'agents diagnostiques ou neuropharmaceutiques-anticorps specifiques de recepteur de transferine Ceased EP0614375A1 (fr)

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AU675057B2 (en) 1997-01-23
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CA2123307A1 (fr) 1993-06-10
WO1993010819A1 (fr) 1993-06-10

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