Patent Application
20210395393
The present invention provides tissue plasminogen activator antibody molecules and their uses. More particularly, the presently-disclosed invention provides humanised antibody molecules which specifically bind tissue plasminogen activator (TPA) and their use in treating TPA induced haemorrhage; in particular treating systemic haemorrhage such as brain haemorrhage after treatment of ischemic stroke or myocardial infarction, or systemic bleeding after TPA treatment of pulmonary embolism, ischemic stroke or myocardial infarction, or in patients wherein endogenous TPA is elevated, including, but not limited to, as a result of prolonged coronary artery bypass surgeries, liver transplantation, severe or poly-trauma, heatstroke, or near drowning.
Tissue plasminogen activator (TPA or tPA) is the only effective medical treatment for ischemic stroke and it also reduces mortality for patients with acute myocardial infarction. (Donnan G A, Davis S M, Parsons M W, Ma H, Dewey H M, Howells D W. How to make better use of thrombolytic therapy in acute ischemic stroke. Nat Rev Neural. 2011; 7:400-409). However, TPA treatment significantly increases the risk of serious or fatal bleeding. Intracranial bleeding after TPA therapy can be devastating and roughly 1% of patients treated with TPA for stroke will experience severely disabling or fatal haemorrhage. (Saver J L. Haemorrhage after thrombolytic therapy for stroke: the clinically relevant number needed to harm. Stroke. 2007; 38:2279-2283.) In a recent study of 511 ischemic stroke patients treated with TPA, up to 20% developed acute deterioration of their mental status necessitating emergent CT scans, revealing a 17% incidence of symptomatic intracranial haemorrhage (sICH), resulting in 87.5% mortality as compared to 22.4% mortality in patients without sICH. (James B, Chang A D, McTaggart R A, et al. Predictors of symptomatic intracranial haemorrhage in patients with an ischaemic stroke with neurological deterioration after intravenous thrombolysis. J Neurol Neurosurg Psychiatry 2018; 89:866-869.) Similar rates of ICH (approximately 6%) are seen with tenecteplase as with Alteplase (Ronning O M, Logallo N, Thommessen B, et al. Tenecteplase versus alteplase between 3 and 4.5 hours in low national institutes of health stroke scale. Stroke 2019; 50(2):498-500), and in a meta-analysis tenecteplase was slightly better in regard to alteplase for the occurrence of any ICH 9.6% versus 11.7% (Xu N, Chen Z, Zhao C, et al. Different doses of tenecteplase vs alteplase in thrombolysis therapy or acute ischemic stroke: evidence from randomized controlled trials. Drug Des Devel Ther 2018; 12:2071-2084). Similarly, 0.9-1.0% of patients given TPA for myocardial infarction develop intracranial haemorrhage and more than 50% of patients die. (Gurwitz J H, Gore J M, Goldberg R J, et al. Risk for intracranial haemorrhage after tissue plasminogen activator treatment for acute myocardial infarction. Participants in the National Registry of Myocardial Infarction 2. Ann Intern Med. 1998; 129:597-604.) Although bleeding complications are often seen in older adults, children are also at significant risk of bleeding from TPA. (Gupta A A, Leaker M, Andrew M, et al. Safety and outcomes of thrombolysis with tissue plasminogen activator for treatment of intravascular thrombosis in children. J Pediatr. 2001; 139:682-688.) Fear of bleeding complications has diminished the therapeutic administration of TPA to patients who might otherwise benefit. (Saver J L. Hemorrhage after thrombolytic therapy for stroke: the clinically relevant number needed to harm. Stroke. 2007; 38:2279-2283.) A recent review of thrombolytic therapy in patients with pulmonary emboli (PE) presented “real world” rates of major bleeding and ICH at >21% and 3.3%, respectively. Further, they concluded that such therapy should only be used in PE patients with unstable cardiovascular status because of these bleeding rates. (Eberle H, Lyn R, Knight T, et al. Clinical update on thrombolytic use in pulmonary embolism: A focus on intermediate-risk patients. Am J Health-Syst Pharm 2018; 75:1275-85). Thus, lack of a specific antidote to TPA or tenecteplase limits access of these agents to the vast majority of PE patients
Once TPA-induced haemorrhage occurs there is no specific TPA inhibitor or antidote available to treat the bleeding. In an effort to restore coagulation, patients are frequently given cryoprecipitate, fresh frozen plasma, and platelets without conclusive evidence of efficacy. (Morgenstern L B, Hemphill J C, 3rd, Anderson C, et al. Guidelines for the management of spontaneous intracerebral haemorrhage: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. 2010 41:2108-2129.) Antifibrinolytic agents such as, tranexamic acid, ε-aminocaproic acid, aprotinin and novel plasmin inhibitors have also been used, but to a limited extent. Unfortunately, these agents not only inhibit the plasminogen (Pg) activation system, but also interfere with other molecular pathways. For example, aprotinin affects plasmin activity as well as the kallikrein system and, has been associated with severe allergies. (Munoz J I, Birkmeyer N J, Birkmeyer J D, O'Connor G T, Dacey L J. Is epsilon-aminocaproic acid as effective as aprotinin in reducing bleeding with cardiac surgery a meta-analysis. Circulation. 1999; 99:81-89.)
The mechanisms responsible for TPA bleeding are still relatively poorly understood. By comparison to streptokinase, activation of Pg by TPA is markedly amplified by fibrin and this distinguishing property of TPA was predicted to increase fibrinolysis without increasing bleeding complications. However, excessive plasmin generation by TPA may degrade clotting factors in the circulation that affect coagulation and may enhance bleeding in vivo. TPA is a multidomain molecule that functions through both catalytic and non-catalytic interactions. There is experimental evidence that non-catalytic actions of TPA (e.g., those not causing plasminogen activation) cause breakdown of the blood brain barrier and are responsible for some of TPA's neurotoxic effects. As such, it is unclear whether TPA-induced brain haemorrhage requires the catalytic activity of TPA. TPA therapy is beneficial in ischemic stroke and myocardial infarction, but in some patients the therapy is complicated by serious or fatal bleeding in the brain and at other sites. Fear of TPA-induced bleeding has limited the therapeutic use of TPA. In humans, TPA-induced haemorrhage and adverse outcomes are more frequent after prolonged ischemia. Similarly, in experimental stroke, after prolonged ischemia, TPA reproducibly causes brain haemorrhage, breakdown of the blood brain barrier and enhanced neuronal cell death.
In non-thrombotic models of stroke there is evidence that TPA may exert toxic effects through mechanisms, such as PDGF-CC cleavage, etc. that do not require plasminogen activation or affect fibrinolytic activity. (Su E J, Fredriksson L, Geyer M, et al. Activation of PDGF-CC by tissue plasminogen activator impairs blood-brain barrier integrity during ischemic stroke. Nat Med. 2008; 14:731-737.) Under pathological conditions such as myocardial ischemia and stroke, the fibrinolytic activity of therapeutic TPA is enhanced by increased levels of circulating fibrin fragments (e.g., D-dimer), which may enhance the bleeding process. (Barber M, Langhorne P, Rumley A, Lowe G D, Stott D J. D-dimer predicts early clinical progression in ischemic stroke: confirmation using routine clinical assays. Stroke. 2006; 37: 1113-1115.)
It is described in international patent application PCT/US2014/012555, published as WO2014/116706A1, that tissue plasminogen activator activates plasminogen through a fibrin-dependent mechanism that contributes to brain haemorrhage after TPA treatment for ischemic stroke.
This summary describes several embodiments of the presently-disclosed subject matter, and, in many cases, lists variations and permutations of these embodiments. This summary is merely exemplary of the numerous and varied embodiments. Mention of one or more representative features of a given embodiment is likewise exemplary. Such an embodiment can typically exist with or without the feature(s) mentioned; likewise, those features can be applied to other embodiments of the presently-disclosed subject matter, whether listed in this summary or not. To avoid excessive repetition, this summary does not list or suggest all possible combinations of such features.
The present invention addresses these and other related needs by providing, inter alia, antibody molecules that are capable of inhibiting TPA-induced fibrinolysis. Tissue plasminogen activator activates plasminogen through a fibrin-dependent mechanism that contributes to systemic haemorrhage, in particular brain haemorrhage, or systemic bleeding after tissue plasminogen activator treatment, more specifically after TPA treatment for ischemic stroke. The antibody molecules of the present invention block this action thereby reducing TPA induced haemorrhage, in particular systemic haemorrhage, more particularly brain haemorrhage, or systemic bleeding after tissue plasminogen activator treatment, more specifically after TPA treatment for ischemic stroke.
The present invention provides an antibody molecule that binds specifically to a human TPA or a TPA mutant. The antibody molecule has sub-nanomolar affinity to inhibit fibrin-dependent plasminogen activation with an IC50<5 nM, and the amino acid sequence of said TPA mutant is at least 65% identical to SEQ ID NO: 1 or SEQ ID NO: 2. The antibody comprises a heavy chain variable domain with a CDR1 selected from the group consisting of SEQ ID NOs: 3 and 4, a CDR2 selected from the group consisting of SEQ ID NO: 5 and 6, and a CDR3 selected from the group consisting of SEQ ID NO: 7 and 8, and a light chain variable domain with a CDR1 selected from the group consisting of SEQ ID NO: 9 and 10, a CDR2 selected from the group consisting of SEQ ID NO: 11 and 12, and a CDR3 of SEQ ID NO: 13.
Typically, the antibody molecule selectively inhibits fibrin-augmented plasminogen activation. Typically, the antibody molecule inhibits degradation of human fibrin clots without affecting TPA amidolytic activity or non-fibrin-dependent activation.
Typically, the antibody molecule is a purified or isolated antibody molecule.
The antibody molecule may be a polyclonal antibody, a monoclonal antibody, a human antibody, a humanized antibody, a chimeric antibody, fragment of an antibody or monoclonal antibody, in particular a Fab, Fab′, or F(ab′)2 fragment, a single chain antibody, in particular a single chain variable fragment (scFv), a domain antibody, a nanobody, a diabody, or a DARPin.
More specifically, the antibody molecule may be a humanized antibody or a fragment of a humanised antibody, in particular a Fab, Fab′, or F(ab′)2 fragment, a single chain antibody, in particular a single chain variable fragment (scFv), a Small Modular Immunopharmaceutical (SMIP), a domain antibody, a nanobody, a diabody, or a Designed Ankyrin Repeat Protein (DARPin).
In one aspect, the present invention provides a pharmaceutical composition comprising an antibody molecule of the present invention and a pharmaceutically acceptable carrier.
To be used in therapy, the antibody molecule is included into pharmaceutical compositions appropriate to facilitate administration to animals or humans. Suitable formulations of the antibody molecule may be prepared by mixing the antibody molecule with physiologically acceptable carriers, excipients or stabilizers, in the form of lyophilized or otherwise dried formulations or aqueous solutions or aqueous or non-aqueous suspensions. Carriers, excipients, modifiers or stabilizers are nontoxic at the dosages and concentrations employed. They include buffer systems such as phosphate, citrate, acetate and other inorganic or organic acids and their salts; antioxidants including ascorbic acid and methionine; preservatives such as octadecyldimethylbenzyl ammonium chloride; hexamethonium chloride; benzalkonium chloride, benzethonium chloride; phenol, butyl or benzyl alcohol; alkyl parabens such as methyl or propyl paraben; catechol; resorcinol; cyclohexanol; 3-pentanol; and m-cresol); proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone or polyethylene glycol (PEG); amino acids such as glycine, glutamine, asparagine, histidine, arginine, or lysine; monosaccharides, disaccharides, oligosaccharides or polysaccharides and other carbohydrates including glucose, man nose, sucrose, trehalose, dextrins or dextrans; chelating agents such as EDTA; sugar alcohols such as, mannitol or sorbitol; salt-forming counter-ions such as sodium; metal complexes (e.g., Zn-protein complexes); and/or ionic or non-ionic surfactants such as TWEEN™ (polysorbates), PLURONICS™ or fatty acid esters, fatty acid ethers or sugar esters. Also organic solvents may be contained in the antibody formulation such as ethanol or isopropanol. The excipients may also have a release-modifying or absorption-modifying function.
In one aspect, the pharmaceutical composition comprises the antibody molecule of the present invention in an aqueous, buffered solution, or a lyophilisate made from such a solution.
A suitable mode of application is parenteral, by infusion or injection (intraveneous, intramuscular, subcutaneous, intraperitoneal, intradermal), but other modes of application such as by inhalation, transdermal, intranasal, buccal, oral, may also be applicable.
In a further aspect, the present invention provides an antibody molecule of the present invention for use as a medicament.
In a further aspect, the present invention provides an antibody molecule of the invention for use in the treatment or prevention of TPA induced haemorrhage.
In one embodiment, the present invention provides an antibody molecule of the invention for use in the treatment or prevention of systemic haemorrhage, in particular brain haemorrhage or systemic bleeding after tissue plasminogen activator treatment, more specifically after TPA treatment for ischemic stroke.
In a further aspect, the present invention provides a method of treatment or prevention of TPA induced haemorrhage, comprising administering an effective amount of an antibody molecule of the invention to a subject in need thereof.
In one embodiment, the present invention provides a method of treatment or prevention of systemic haemorrhage, in particular brain haemorrhage or systemic bleeding after tissue plasminogen activator treatment, more specifically after TPA treatment for ischemic stroke, comprising administering an effective amount of an antibody molecule of the invention to a subject in need thereof.
In a further aspect, the present invention provides a kit comprising an antibody molecule of the present invention, or a pharmaceutical composition thereof.
In one aspect, the present invention provides a method of manufacturing an antibody molecule of the present invention, comprising:
(a) providing a host cell comprising one or more nucleic acids encoding said antibody molecule in functional association with an expression control sequence,
(b) cultivating said host cell, and
(c) recovering the antibody molecule from the cell culture.
In a further aspect, the present invention provides a method for identifying molecules that can inhibit TPA-induced fibrinolysis of human clots. The method includes the steps of: providing an antibody molecule of the present invention that specifically binds to TPA and inhibits TPA-induced fibrinolysis of human clots, affixing the antibody molecule to a surface, providing TPA and introducing an agent to the TPA that blocks the non-specific binding regions of TPA, introducing a candidate molecule to the TPA, introducing the TPA to the antibody molecule, determining if the candidate molecule has bound to the epitope of the TPA where the antibody molecule had bound to the TPA, and identifying any candidate molecule binding to the epitope as a molecule that can inhibit TPA-induced fibrinolysis of human clots.
Advantages of the presently-disclosed subject matter will become evident to those of ordinary skill in the art after a study of the description, Figures, and non-limiting Examples in this document.
Some of the polypeptide sequences disclosed herein are cross-referenced to GENBANK® accession numbers. The sequences cross-referenced in the GENBANK® database are expressly incorporated by reference as are equivalent and related sequences present in GENBANK® or other public databases. Also expressly incorporated herein by reference are all annotations present in the GENBANK® database associated with the sequences disclosed herein.
The present invention provides an antibody molecule that binds specifically to a human TPA or a TPA mutant to inhibit degradation of human fibrin clots, wherein the antibody has sub-nanomolar affinity to inhibit fibrin-dependent plasminogen activation with an IC50<5 nM, and wherein the amino acid sequence of said TPA mutant has at least 65% identity to SEQ ID NO: 1 or SEQ ID NO: 2; wherein the antibody comprises a heavy chain variable domain with a CDR1 selected from the group consisting of SEQ ID NOs: 3 and 4, a CDR2 selected from the group consisting of SEQ ID NO: 5 and 6, and a CDR3 selected from the group consisting of SEQ ID NO: 7 and 8, and a light chain variable domain with a CDR1 selected from the group consisting of of SEQ ID NO: 9 and 10, a CDR2 selected from the group consisting of SEQ ID NO: 11 and 12, and a CDR3 of SEQ ID NO: 13.
This invention relates to the provision and use of antibody molecules as specific inhibitors of fibrin-dependent Pg activation in TPA-induced haemorrhage, in particular systemic haemorrhage such as brain haemorrhage, systemic bleeding after tissue plasminogen activator treatment. More specifically, certain antibody molecules function as inhibitors and act synergistically to reduce plasminogen activation and fibrinolysis with greater potency than plasminogen activator inhibitor-I (PAI-I). In a model of thromboembolic stroke, these inhibitors significantly reduced brain haemorrhage and surgical bleeding after TPA administration.
The present invention provides an antibody molecule that binds specifically to a human TPA or a TPA mutant to inhibit degradation of human fibrin clots, wherein the antibody has sub-nanomolar affinity to inhibit fibrin-dependent plasminogen activation with an IC50<5 nM, and wherein the amino acid sequence of said TPA mutant has at least 65% identity to SEQ ID NO: 1 or SEQ ID NO: 2. In some embodiments, the antibody molecule does not affect TPA amidolytic activity or non-fibrin-dependent activation. The amino acid sequence of the TPA mutant is at least 65% identical to SEQ ID NO: 1 or SEQ ID NO: 2. The TPA mutant may thus also have homologies with these sequences greater than 65%, e.g., 70%, 75%, 80%, 85%, 90%, 95% and so on. A non-limiting example of a TPA mutant is reteplase, which is a TPA deletion mutant which has 67.7% of the residues found in full length TPA. An alternative non-limiting example of a TPA mutant is tenecteplase, which is a TPA substitution mutant which is a 527 amino acid glycoprotein developed by introducing the following modifications to the complementary DNA (cDNA) for natural human tPA: a substitution of threonine 103 with asparagine, and a substitution of asparagine 117 with glutamine, both within the kringle 1 domain, and a tetra-alanine substitution at amino acids 296-299 in the protease domain. In some embodiments, the amino acid sequence of the human TPA is SEQ ID NO: 1 or SEQ ID NO: 2.
It is an object of the present invention to produce an antibody molecule specific for the TPA with sub-nanomolar dissociation constant (for a review on the definitions and measurements of antibody-antigen affinity, see Neri et al. (1996). Trends in Biotechnol. 14, 465-470).
The present invention provides an antibody molecule that binds specifically to a human TPA or a TPA mutant to inhibit degradation of human fibrin clots, wherein the antibody has sub-nanomolar affinity to inhibit fibrin-dependent plasminogen activation with an IC50<5 nM, and wherein the amino acid sequence of said TPA mutant has at least 65% identity to SEQ ID NO: 1 or SEQ ID NO: 2; wherein the antibody comprises a heavy chain variable domain with a CDR1 selected from the group consisting of SEQ ID NOs: 3 and 4, a CDR2 selected from the group consisting of SEQ ID NO: 5 and 6, and a CDR3 selected from the group consisting of SEQ ID NO: 7 and 8, and a light chain variable domain with a CDR1 selected from the group consisting of of SEQ ID NO: 9 and 10, a CDR2 selected from the group consisting of SEQ ID NO: 11 and 12, and a CDR3 of SEQ ID NO: 13.
In one embodiment, the antibody molecule of the present invention comprises a heavy chain variable domain with a CDR1 of SEQ ID NO: 3, a CDR2 of SEQ ID NO: 5, and a CDR3 of SEQ ID NO: 7, and a light chain variable domain with a CDR1 of SEQ ID NO: 9, a CDR2 of SEQ ID NO: 11, and a CDR3 of SEQ ID NO: 13.
In a further embodiment, the antibody molecule of the present invention comprises a heavy chain variable domain selected from the group consisting of SEQ ID NOs: 14 to 28 and a light chain variable domain selected from the group consisting of SEQ ID NOs: 29 and 30.
In a further embodiment, the antibody molecule of the present invention comprises a heavy chain variable domain selected from the group consisting of SEQ ID NOs: 14 to 28, and a light chain variable domain of SEQ ID NO: 29.
In one embodiment, the antibody molecule of the present invention comprises a heavy chain variable domain of SEQ ID NO: 14, and a light chain variable domain of SEQ ID No: 29, or a heavy chain variable domain of SEQ ID NO: 15, and a light chain variable domain of SEQ ID No: 29, or a heavy chain variable domain of SEQ ID NO: 14, and a light chain variable domain of SEQ ID No: 30, or a heavy chain variable domain of SEQ ID NO: 15, and a light chain variable domain of SEQ ID No: 30.
In one embodiment, the antibody molecule of the present invention has a heavy chain comprising SEQ ID NO: 40 or SEQ ID NO: 41, and a light chain comprising SEQ ID NO: 42.
The term “mutant” as used herein includes a peptide with a sequence substantially similar to the sequence of TPA. It is known in the art that a substantially similar amino acid sequence to a reference peptide may yield a mutant peptide with no substantial change in physiological, chemical, or functional properties compared to the reference peptide. In such a case, the reference and mutant peptides would be considered “substantially identical” polypeptides. Sequence identity is used to evaluate the similarity of two sequences; it is determined by calculating the percent of residues that are the same when the two sequences are aligned for maximum correspondence between residue positions. Any known method may be used to calculate sequence identity; for example, computer software is available to calculate sequence identity. Without wishing to be limiting, sequence identity can be calculated by software such as BLAST-P, BLAST-N, or FASTA-N, or any other appropriate software that is known in the art. The substantially identical sequences of the present invention may be at least 65% identical. In another example, the substantially identical sequences may be at least 65, 70, 75, 80, 85, 90, 95, or 100% identical at the amino acid level to sequences described herein.
Antibodies (also known as immunoglobulins, abbreviated Ig) are gamma globulin proteins that can be found in blood or other bodily fluids of vertebrates, and are used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses. They are typically made of basic structural units—each with two large heavy chains and two small light chains—to form, for example, monomers with one unit, dimers with two units or pentamers with five units. Antibodies can bind, by non-covalent interaction, to other molecules or structures known as antigens. This binding is specific in the sense that an antibody will only bind to a specific structure with high affinity. The unique part of the antigen recognized by an antibody is called an epitope, or antigenic determinant. The part of the antibody binding to the epitope is sometimes called paratope and resides in the so called variable domain, or variable region (Fv) of the antibody. The variable domain comprises three so-called complementary-determining region (CDR's) spaced apart by framework regions (FR's).
Within the context of this invention, reference to CDRs is based on the definition of Chothia (Chothia and Lesk, J. Mol. Biol. 1987, 196: 901-917), together with Kabat (E. A. Kabat, T. T. Wu, H. Bilofsky, M. Reid-Miller and H. Perry, Sequence of Proteins of Immunological Interest, National Institutes of Health, Bethesda (1983)).
Antibodies have been developed to be useful in medicine and technology. Thus, in the context of the present invention the terms “antibody molecule” or “antibody” (used synonymously herein) do not only include antibodies as they may be found in nature, comprising e.g. two light chains and two heavy chains, or just two heavy chains as in camelid species, but furthermore encompasses all molecules comprising at least one paratope with binding specificity to an antigen and structural similarity to a variable domain of an immunoglobulin.
The term “antibody” (Ab) as used herein includes monoclonal antibodies, polyclonal antibodies, multispecific antibodies and antibody fragments, as long as they exhibit the desired biological activity. The term “polyclonal antibody” as used herein refers to a collection of antibody molecules with different amino acid sequences and may be obtained from the blood of vertebrates after immunization with the antigen by processes well-known in the art. The term “monoclonal antibody” as used herein refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies that make up the population are identical except for possible naturally occurring mutations. Monoclonal antibodies are highly specific, being directed against a single antigenic site. For example, the monoclonal antibodies useful in the present invention may be prepared by the hybridoma methodology from a hybrid cell line (called hybridoma) representing a clone of a fusion of a specific antibody-producing B cell with a myeloma (B cell cancer) cell described by Kohler et al., Nature, 256:495 (1975), or may be made using recombinant DNA methods in bacterial, eukaryotic animal or plant cells (see, e.g., U.S. Pat. No. 4,816,567). Additionally, the “monoclonal antibodies” may also be isolated from phage antibody libraries using the techniques described in Clackson et al., Nature, 352:624-628 (1991) and Marks et al., J. Mol. Biol., 222:581-597 (1991), for example.
For application in man, it is often desirable to reduce immunogenicity of antibodies originally derived from other species, such as mouse. This can be done by construction of chimeric antibodies, or by a process called “humanization”. In this context, a “chimeric antibody” is understood to be an antibody comprising a sequence part (e.g. a variable domain) derived from one species (e.g. mouse) fused to a sequence part (e.g. the constant domains) derived from a different species (e.g. human). A “humanized antibody” is an antibody comprising a variable domain originally derived from a non-human species, wherein certain amino acids have been mutated to resemble the overall sequence of that variable domain more closely to a sequence of a human variable domain. Methods of chimerisation and humanization of antibodies are known in the art (Billetta R, Lobuglio A F. “Chimeric antibodies”. Int Rev Immunol. 1993; 10(2-3):165-76; Riechmann L, Clark M, Waldmann H, Winter G (1988). “Reshaping human antibodies for therapy” Nature: 332:323).
The creation and development of monoclonal antibodies/monoclonal antibody fragments (mAbs/Fabs) drug candidate molecules is however complex. Despite the fact that many techniques used in the production of mAbs/Fabs have been standardized, each Mab/Fab is unique, due to its specific structure derived from its origin of binding to a specific antigen target. In addition, they “are far more complex to produce and characterize than small molecules as they are 200-1000× larger, structurally more complex, and highly sensitive to their manufacturing conditions.” (Kizhedath A, Wilkinson S and Glassey J. Applicability of predictive toxicology methods for monoclonal antibody therapeutics: status Quo and scope. Arch Toxicol 2017; 91:1595-1612.). Another layer of complexity is added when one considers the unique changes required to each candidate molecule to optimize its pharmacodynamic and pharmacokinetic properties, while reducing its potential toxicokinetic properties, such as immunogenicity, off-target or immunostimulating (cytokine storm) effects.
Furthermore, technologies have been developed for creating antibodies based on sequences derived from the human genome, for example by phage display or using transgenic animals (WO 90/05144; D. Marks, H. R. Hoogenboom, T. P. Bonnert, J. Mccafferty, A. O. Griffiths and G. Winter (1991) “By-passing immunisation. Human antibodies from V-gene libraries displayed on phage.” J. Mol. Biol., 222, 581-597; Knappik et al., J. Mol. Biol. 296: 57-86, 2000; S. Carmen and L. Jermutus, “Concepts in antibody phage display”. Briefings in Functional Genomics and Proteomics 2002 1 (2):189-203; Lonberg N, Huszar D. “Human antibodies from transgenic mice”. Int Rev Immunol. 1995; 13(1):65-93.; Bruggemann M, Taussig M J. “Production of human antibody repertoires in transgenic mice”. Curr Opin Biotechnol. 1997 August; 8(4):455-8.). Such antibodies are “human antibodies” in the context of the present invention.
The monoclonal antibodies herein include “chimeric” antibodies in which a portion of the heavy and/or light chain is identical with or homologous to corresponding sequences in antibodies derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain(s) is identical with or homologous to corresponding sequences in antibodies derived from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies, so long as they exhibit the desired biological activity (see U.S. Pat. No. 4,816,567; and Morrison et al., Proc. Natl. Acad. Sci. USA, 81:6851-6855 (1984)).
The term “antibody” (Ab) as used herein also includes antibody fragments. An “antibody fragment” is a portion of an intact antibody, preferably the antigen binding or variable region of the intact antibody. Examples of antibody fragments include but are not limited to: Fab, Fab′, F(ab′)2, and Fv fragments; diabodies; linear antibodies (see U.S. Pat. No. 5,641,870, Example 2; Zapata et al., Protein Eng. 8(10): 1057-1062 [1995]); single-chain antibody molecules; and multispecific antibodies formed from antibody fragments. Such fragments may be obtained by fragmentation of immunoglobulins e.g. by proteolytic digestion, or by recombinant expression of such fragments. For example, immunoglobulin digestion can be accomplished by means of routine techniques, e.g. using papain or pepsin (WO 94/29348), or endoproteinase Lys-C (Kleemann, et al, Anal. Chem. 80, 2001-2009, 2008). Papain or Lys-C digestion of antibodies typically produces two identical antigen binding fragments, so-called Fab fragments, each with a single antigen binding site, and a residual Fc fragment. Pepsin treatment yields an F(ab′)2. Methods of producing Fab molecules by recombinant expression in host cells are outlined in more detail below.
A number of technologies have been developed for placing variable domains of immunoglobulins, or molecules derived from such variable domains, in a different structural context. Those should be also considered as “antibody molecules” in accordance with the present invention. In general, these antibody molecules are smaller in size compared to immunoglobulins, and may comprise a single amino acid chain or be comprised of several amino acid chains. For example, a single-chain variable fragment (scFv) is a fusion of the variable regions of the heavy and light chains of immunoglobulins, linked together with a short linker, usually serine (S) or glycine (G) (WO 88/01649; WO 91/17271; Huston et al; International Reviews of Immunology, Volume 10, 1993, 195-217). “Single domain antibodies” or “nanobodies” include an antigen-binding site in a single Ig-like domain (WO 94/04678; WO 03/050531, Ward et al., Nature. 1989 Oct. 12; 341 (6242):544-6; Revets et al., Expert Opin Biol Ther. 5(1):111-24, 2005). One or more single domain antibodies with binding specificity for the same or a different antigen may be linked together. Diabodies are bivalent antibody molecules consisting of two amino acid chains comprising two variable domains (WO 94/13804, Holliger et al., Proc Natl Acad Sci USA. 1993 Jul. 15; 90(14):6444-8). Other examples for antibody-like molecules are immunoglobulin super family antibodies (IgSF; Srinivasan and Roeske, Current Protein Pept. Sci. 2005, 6(2): 185-96). Alternatively, Small Modular Immunopharmaceuticals (SMIP) comprises a Fv domain linked to single-chain hinge and effector domains devoid of the constant domain CH1 (WO 02/056910).
Thus, an antibody molecule according to the present invention may be a polyclonal antibody, a monoclonal antibody, a human antibody, a humanized antibody, a chimeric antibody, a fragment of an antibody, in particular a Fab, Fab′, or F(ab′)2 fragment, a single chain antibody, in particular a single chain variable fragment (scFv), a Small Modular Immunopharmaceutical (SMIP), a domain antibody, a nanobody, a diabody, or a Designed Ankyrin Repeat Protein (DARPin).
In one embodiment, the antibody molecule of the present invention is a humanized antibody or a fragment of a humanised antibody, in particular a Fab, Fab′, or F(ab′)2 fragment, a single chain antibody, in particular a single chain variable fragment (scFv), a Small Modular Immunopharmaceutical (SMIP), a domain antibody, a nanobody, a diabody, or a Designed Ankyrin Repeat Protein (DARPin).
In a further embodiment, the antibody molecule of the present invention is a humanized antibody or a fragment of a humanised antibody, in particular a Fab, Fab′, or F(ab′)2 fragment.
The variable domains disclosed above may each be fused to an immunoglobulin constant domain, preferably of human origin. Thus, the heavy chain variable domain may be fused to a CH1 domain (a so-called Fd fragment), and the light chain variable domain may be fused to a CL domain.
In one embodiment, the antibody molecule of the present invention is a Fab molecule, in particular a humanised Fab molecule, having a Fd fragment comprising SEQ ID NO: 31 or SEQ ID NO: 32, and a light chain comprising SEQ ID NO: 33.
Fab molecules can be generated from full-length antibody molecules by enzymatic cleavage, in which the whole antibody is cleaved by an enzyme such as papain, pepsin, or ficin. The advantage of this approach is that platform processes for robust and efficient fermentation and purification are applicable which are amenable for up-scaling and high yields at the desired product quality. For purification, affinity chromatography using a recombinant Protein A resin can be used to separate the Fab fragment from the Fc (fragment that crystallizes) and residual intact antibody. Using protein A affinity chromatography typically results in high purities.
Alternatively, nucleic acids encoding Fab constructs may be used to express such heavy and light chains in host cells, like E. coli, Pichia pastoris, or mammalian cell lines (e.g., CHO, HEK293, or NSO). Processes are known in the art which allow proper folding, association, and disulfide bonding of these chains into functional Fab molecules comprising a Fd fragment and a light chain (Burtet et al., J. Biochem. 2007, 142(6), 665-669; Ning et al., Biochem. Mol. Biol. 2005, 38: 204-299; Quintero-Hernandez et al., Mol. Immunol. 2007, 44: 1307-1315; Willems et al. J. Chromatogr. B. Analyt. Technol. Biomed. Life Sci. 2003; 786:161-176.).
In one embodiment, the antibody molecule of the present invention is a scFv molecule.
The variable domains disclosed herein may be fused to each other with a suitable linker peptide, e.g. selected from the group consisting of SEQ ID Nos: 33, 34, 35, or 36. The construct may comprise these elements in the order, from N terminus to C terminus, (heavy chain variable domain)-(linker peptide)-(light chain variable domain), or (light chain variable domain)-(linker peptide)-(heavy chain variable domain).
In a further embodiment, the antibody molecule of the present invention is a scFv wherein the heavy chain variable domain and the light chain variable domain are linked to each other through a linker peptide selected from the group consisting of SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, and SEQ ID NO: 37.
In a further embodiment, the antibody molecule of the present invention comprises SEQ ID NO: 38, or SEQ ID NO:39.
Processes are known in the art which allow recombinant expression of nucleic acids encoding scFv constructs in host cells (like E. coli, Pichia pastoris, or mammalian cell lines, e.g. CHO or NSO), yielding functional scFv molecules (see e.g. Rippmann et al., Applied and Environmental Microbiology 1998, 64(12): 4862-4869; Yamawaki et al., J. Biosci. Bioeng. 2007, 104(5): 403-407; Sonoda et al., Protein Expr. Purif. 2010, 70(2): 248-253).
The antibody molecule of the present invention may be fused (as a fusion protein) or otherwise linked (by covalent or non-covalent bonds) to other molecular entities having a desired impact on the properties of the antibody molecule. For example, it may be desirable to improve pharmacokinetic properties of antibody molecules, or stability e.g. in body fluids such as blood, in particular in the case of single chain antibodies or domain antibodies. A number of technologies have been developed in this regard, in particular to prolong half-life of such antibody molecules in the circulation, such as pegylation (WO 98/25971; WO 98/48837; WO 2004081026), fusing or otherwise covalently attaching the antibody molecule to another antibody molecule having affinity to a serum protein like albumin (WO 2004041865; WO 2004003019), or expression of the antibody molecule as fusion protein with all or part of a serum protein like albumin or transferrin (WO 01/79258).
In a further aspect of the invention, the antibody molecule is capable of neutralizing the activity of the fibrinolytic agent. That is, upon binding to the antibody molecule, the TPA is no longer able to exert its fibrinolytic activity through plasminogen activation, or exerts this activity at a significantly decreased magnitude. Preferably, the fibrinolytic activity is decreased at least 2-fold, 5-fold, 10-fold, or 100-fold upon antibody binding, as determined in an activity assay (Longstaff C, Whitton C M. A proposed reference method for plasminogen activators that enables calculation of enzyme activities in SI units. J Thromb Haemost. 2004; 2: 1416-1421) which is appropriate, and particularly a clotting assay that is sensitive to fibrin degratory factors, such as the measurement of D-D-Dimer (Gebhardt J, Kepa S, Hofer S, Koder S, et al. Fibrinolysis in patients with mild-to-moderate bleeding tendency or unknown cause. Ann Hematol 2017; 96:489-495).
For manufacturing the antibody molecules of the invention, the skilled artisan may choose from a variety of methods well known in the art (Norderhaug et al., J Immunol Methods 1997, 204 (1): 77-87; Kipriyanow and Le Gall, Molecular Biotechnology 26: 39-60, 2004; Shukla et al., 2007, J. Chromatography B, 848(1): 28-39).
Human TPA and mutants are well-known in the art, as outlined above. In this context, TPA includes TPA and mutants.
TPA-induced brain and systemic bleeding in vivo is blocked by potent synergistic inhibitors of TPA's fibrin-dependent plasminogen activation. This implies that haemorrhage is related to TPA's fibrin-targeted mechanism of plasminogen activation and that targeted inhibitors of this process may serve as specific antidotes for TPA associated haemorrhage. TPA therapy is beneficial in ischemic stroke and myocardial infarction, but in some patients it is complicated by serious or fatal bleeding in the brain and at other sites. Fear of TPA-induced bleeding has limited the therapeutic use of TPA. In humans, TPA-induced haemorrhage and adverse outcomes are more frequent after prolonged ischemia. Similarly, in experimental stroke, after prolonged ischemia, TPA reproducibly causes brain haemorrhage, breakdown of the blood brain barrier and enhanced neuronal cell death. In non-thrombotic models of stroke there is evidence that TPA may exert toxic effects through mechanisms, such as PDGF-CC cleavage, etc. that do not require plasminogen activation or affect fibrinolytic activity (Su E J, Fredriksson L, Geyer M, et al. Activation of PDGF-CC by tissue plasminogen activator impairs blood-brain barrier integrity during ischemic stroke. Nat Med. 2008; 14:731-737). Under pathological conditions like myocardial ischemia and stroke, the fibrinolytic activity of therapeutic TPA is enhanced by increased levels of circulating fibrin fragments (e.g., D-dimer), which may enhance the bleeding process. (Barber M, Langhorne P, Rumley A, Lowe G D, Stott D J. D-dimer predicts early clinical progression in ischemic stroke: confirmation using routine clinical assays. Stroke. 2006; 37:1113-1115.)
In addition to therapeutic use of TPA, elevated TPA levels have been associated with excessive systemic bleeding. TPA-induced bleeding has been suspected in patients' post-cardiopulmonary bypass. (Manji R A, Grocott H P, Leake J, et al. Seizures following cardiac surgery: the impact of tranexamic acid and other risk factors. Can J Anaesth. 2012; 59:6-13.) In a similar fashion, in disease conditions such as liver failure and transplantation, high levels of circulating TPA have been linked to bleeding. (Leiper K, Croll A, Booth N A, Moore N R, Sinclair T, Bennett B. Tissue plasminogen activator, plasminogen activator inhibitors, and activator-inhibitor complex in liver disease. J Clin Pathol. 1994; 47:214-217). Fibrinolytic inhibitors (e.g., tranexamic acid, ε-aminocaproic acid, aprotinin, etc.) reduce the risk of transfusion after surgery (Bayes-Genis A, Mateo J, Santalo M, et al. D-Dimer is an early diagnostic marker of coronary ischemia in patients with chest pain. Am Heart J. 2000; 140:379-384). However, these agents have broad inhibitory effects on other pathways and associated toxicities. For example, tranexamic acid increases seizures risk after cardiac surgery. (Manji R A, Grocott H P, Leake J, et al. Seizures following cardiac surgery: the impact of tranexamic acid and other risk factors. Can J Anaesth. 20 I2; 59:6-13). Broad inhibition of fibrinolysis may carry a risk of subsequent thrombotic episodes such stroke, thromboembolism. (Fergusson D A, Hebert P C, Mazer C D, et al. A comparison of aprotinin and lysine analogues in high-risk cardiac surgery. N Engi J Med. 2008; 358:2319-2331). This concern was magnified by the unexpected finding that aprotinin use increased mortality following cardiac surgery (ibid).
Severe trauma or trauma producing poly-organ damage produces a hyperfibrinolytic state that is mediated by elevated endogenous TPA levels (Cardenas J C, Matijevic N, Baer L A, Holcomb J B, Cotton B A, Wade C E. Elevated tissue plasminogen activator and reduced plasminogen activator inhibitor promote hyperfibrinolysis in trauma patients. Shock 2014; 41(6):514-21). Thus, inhibition of elevated endogenous TPA by an antibody agent could normalize fibrinolysis and prevent the coagulopathy seen in these conditions. Tranexamic acid has been studied in severely injured trauma patients with hyperfibrinolysis caused by elevated endogenous TPA, producing increased 6 hour survival but not affecting long term survival (Khan M, Jehan F, Bulger E M, et al. Severely injured trauma patients with admission hyperfibrinoloysis: Is there a role of tranexamic acid? Findings from the PROPPR trial. J Trauma Acute Care Surg 2018; 85(5):851-857).
The use of anti-fibrinolytic agents for treating TPA-induced haemorrhage is still very limited, possibly because these agents are known to interfere with other biochemical pathways. PAI-I or PAI-I mutants have been shown to suppress TPA-induced bleeding after injury. However, in addition to inhibiting TPA, PAI-I inhibits uPA, and several other proteases. Through its non-proteinase interactions with vitronectin, heparin, members of the low-density lipoprotein-receptor family and other molecules, PAI-I has ‘pleiotropic’ effects on numerous other biological processes and has been implicated in the pathophysiology of several disease processes. Thus PAI-I has roles in angiogenesis, apoptosis, cell migration and cancer that involve both inhibitory and non-inhibitory functions.
In one aspect, the present invention provides a pharmaceutical composition comprising an antibody molecule of the present invention and a pharmaceutically acceptable carrier.
In a further aspect, the present invention provides an antibody molecule of the present invention for use as a medicament.
In a further aspect, the present invention provides an antibody molecule of the invention for use in the treatment or prevention of TPA induced haemorrhage.
As described above, elevated levels of TPA may be as a result of exogenous or endogenous processes i.e. specific administration of TPA or as a result of elevated levels of TPA being generated in vivo, for example following cardiopulmonary bypass. In this context, ‘TPA induced haemorrhage’ includes haemorrhage induced by elevated levels of TPA resulting from exogenous or endogenous processes.
The antibody molecule inhibits fibrinolysis induced by TPA. In some embodiments, the antibody molecule inhibits the initiation of fibrinolysis. In some embodiments, the antibody molecule inhibits fibrinolysis in progress.
In one embodiment, the present invention provides an antibody molecule of the invention for use in the treatment or prevention of systemic haemorrhage, in particular brain haemorrhage and systemic bleeding after tissue plasminogen activator treatment, more specifically after TPA treatment for ischemic stroke.
In an alternative embodiment, the present invention provides an antibody molecule of the invention for use in the treatment or prevention of systemic haemorrhage in subjects wherein endogenous TPA is elevated, including, but not limited to, as a result of prolonged coronary artery bypass surgeries, liver transplantation, severe or poly-trauma, heatstroke, and near drowning.
In a further aspect, the present invention provides a method of treatment or prevention of TPA induced haemorrhage, comprising administering an effective amount of an antibody molecule of the invention to a subject in need thereof.
In one embodiment, the present invention provides a method of treatment or prevention of systemic haemorrhage, in particular brain haemorrhage and systemic bleeding after tissue plasminogen activator treatment, more specifically after TPA treatment for ischemic stroke, comprising administering an effective amount of an antibody molecule of the invention to a subject in need thereof.
In an alternative embodiment, the present invention provides a method of treatment or prevention of systemic haemorrhage in subjects wherein endogenous TPA is elevated, including, but not limited to, as a result of prolonged coronary artery bypass surgeries, liver transplantation, severe or poly-trauma, heatstroke, or near drowning, comprising administering an effective amount of an antibody molecule of the invention to a subject in need thereof.
In a further aspect, the present invention provides a kit comprising an antibody molecule of the present invention, or a pharmaceutical composition thereof.
In one embodiment the kit comprises:
(a) an antibody of the present invention or a pharmaceutical composition thereof;
(b) a container; and
(c) a label.
In one embodiment the kit comprises an antibody of the present invention or a pharmaceutical composition thereof and human tissue plasminogen activator (TPA) or a TPA mutant wherein the amino acid sequence of said TPA mutant has at least 65% identity to SEQ ID NO: 1 or SEQ ID NO: 2.
In a further embodiment, the human tissue plasminogen activator (TPA) or TPA mutant is selected from alteplase (Activase®, Actilyse®; rtPA), reteplase (Retavase®, Rapilysin®) and tenecteplase (TNKase®; TNK-tPA).
In a further embodiment, the kit comprises:
(a) an antibody of the present invention or a pharmaceutical composition thereof;
(b) a pharmaceutical composition comprising human tissue plasminogen activator (TPA) or TPA mutant selected from alteplase (Activase®, Actilyse®; rtPA), reteplase (Retavase®, Rapilysin®) and tenecteplase (TNKase®; TNK-tPA);
(c) a container; and
(d) a label.
In a further embodiment, the kit comprises:
(a) a first pharmaceutical composition comprising human tissue plasminogen activator (TPA) or TPA mutant selected from alteplase (Activase®, Actilyse®; rtPA), reteplase (Retavase®, Rapilysin®) and tenecteplase (TNKase®; TNK-tPA);
(b) a second pharmaceutical composition comprising antibody of the present invention;
(c) instructions for separate administration of the first and second pharmaceutical compositions to a subject, wherein the first and second pharmaceutical compositions are contained in separate containers and the second pharmaceutical composition is administered to a subject requiring treatment or prevention of systemic haemorrhage after TPA treatment.
In this context, a ‘subject requiring treatment’ is one displaying symptoms of severe haemorrhage and a ‘subject requiring prevention’ is one displaying no symptoms of severe haemorrhage, but judged as high risk by a treating physician.
In one aspect, the present invention provides a method of manufacturing an antibody molecule of the present invention, comprising:
(a) providing a host cell comprising one or more nucleic acids encoding said antibody molecule in functional association with an expression control sequence,
(b) cultivating said host cell, and
(c) recovering the antibody molecule from the cell culture.
A “purified or isolated antibody” is one which has been identified and separated and/or recovered from a component of its natural environment. Contaminant components of its natural environment are materials which would interfere with diagnostic or therapeutic uses for the antibody, and may include enzymes, hormones, and other proteinaceous or non-proteinaceous solutes. Preferably, the antibody will be purified (1) to greater than 95% by weight of antibody as determined by the Lowry method, and most preferably more than 99% by weight, (2) to a degree sufficient to obtain at least 15 residues of N-terminal or internal amino acid sequence by use of a spinning cup sequenator, or (3) to homogeneity by SDS-PAGE under reducing or non-reducing conditions using Coomassie blue or, preferably, silver stain. Isolated antibody includes the antibody in situ within recombinant cells since at least one component of the antibody's natural environment will not be present.
As used herein, the term “treat”, “treating” or “treatment” of any disease or disorder refers in one embodiment, to ameliorating the disease or disorder (i.e., slowing or arresting or reducing the development of the disease or at least one of the clinical symptoms thereof). In another embodiment “treat”, “treating” or “treatment” refers to alleviating or ameliorating at least one physical parameter including those which may not be discernible by the patient. In yet another embodiment, “treat”, “treating” or “treatment” refers to modulating the disease or disorder, either physically, (e.g., stabilization of a discernible symptom), physiologically, (e.g., stabilization of a physical parameter), or both. In yet another embodiment, “treat”, “treating” or “treatment” refers to preventing or delaying the onset or development or progression of the disease or disorder.
“Prevention” of a condition or disorder refers to delaying or preventing the onset of a condition or disorder or reducing its severity, as assessed by the appearance or extent of one or more symptoms of said condition or disorder.
As used herein, the term “subject” refers to an animal. Typically the animal is a mammal. A subject also refers to for example, primates (e.g., humans), cows, sheep, goats, horses, dogs, cats, rabbits, rats, mice, fish, birds and the like. In certain embodiments, the subject is a primate. In yet other embodiments, the subject is a human.
As used herein, a subject is “in need of” a treatment if such subject would benefit biologically, medically or in quality of life from such treatment.
As used herein, a subject wherein ‘endogenous TPA is elevated’ refers to a subject wherein the plasma concentration of endogenous TPA is increased with respect to baseline levels. The World Health Organization (WHO/BS/07.2068, 2007) quotes normal plasma levels of tPA as <10 ng/mL with most values reported at ˜4 ng/mL. 5-10-fold elevations have been reported in subjects with hyperfibrinolysis (Chapman et al., Overwhelming tPA Release, not PAI-1 Degradation, is Responsible for Hyperfibrinolysis in Severely Injured Trauma Patients, J Trauma Acute Care Surg. 2016 January; 80(1): 16-25; Duque et al., Pathophysiological Response to Trauma-Induced Coagulopathy: A Comprehensive Review, 2019 Anesthesia & Analgesia: Oct. 15, 2019—Volume Publish Ahead of Print—Issue—p doi: 10.1213/ANE.0000000000004478).
The compositions of the invention may include an “effective amount” or “therapeutically effective amount” or a “prophylactically effective amount” of an antibody or antigen-binding portion of the invention. These terms are used interchangeably. A “therapeutically effective amount” refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired therapeutic result. A therapeutically effective amount of the antibody or antibody portion may vary according to factors such as the disease state, age, sex, and weight of the subject, and the ability of the antibody or antibody portion to elicit a desired response in the subject. Dosage unit form as used herein refers to physically discrete units suited as unitary dosages for the mammalian subjects to be treated; each unit containing a predetermined quantity of active compound calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier.
In a further aspect, the present invention provides a method for identifying molecules that can inhibit TPA-induced fibrinolysis of human clots. The method includes the steps of: providing an antibody molecule of the present invention that specifically binds to TPA and inhibits TPA-induced fibrinolysis of human clots, affixing the antibody molecule to a surface, providing TPA and introducing an agent to the TPA that blocks the non-specific binding regions of TPA, introducing a candidate molecule to the TPA, introducing the TPA to the antibody molecule, determining if the candidate molecule has bound to the epitope of the TPA where the antibody molecule had bound to the TPA, and identifying any candidate molecule binding to the epitope as a molecule that can inhibit TPA-induced fibrinolysis of human clots. In one example of the embodiment, an antibody molecule of the invention is immobilized in the wells of a microtiter plate. Non-specific protein binding sites are blocked. A mixture of TPA and the potential new inhibitor molecule, pre-incubated together are added to the wells containing immobilized antibody molecule. After an hour, wells are washed and polyclonal anti-TPA antibody coupled to peroxidase is added. After an hour, wells are washed and the peroxidase substrate TMB is added and the A370 is monitored. Wells with reduced A370 contain molecules that compete with the antibody molecule of the invention for TPA binding and are thus prime candidates as specific TPA inhibitors. That will be confirmed in detailed studies of human clot lysis initiated by TPA.
The following examples are intended to illustrate the invention and are not to be construed as being limitations thereon.
Abbreviations used are those conventional in the art. If not defined, the terms have their generally accepted meanings.
Abbreviations and acronyms used herein include the following:
1.1 Monoclonal Antibody Generation
C57BL/6J mice (Jackson Laboratory, Bar Harbor, Me.) were immunized with recombinant human TPA (Genentech) followed by fusion of splenocytes isolated from the immunized mouse with myeloma cells using the conventional hybridoma techniques (Nelson P N, Reynolds G M, Waldron E E, Ward E, Giannopoulos K, Murray P G. Monoclonal antibodies. Mol Pathol. 2000; 53: 111-117). Microplate ELISA assays were performed to screen positive clones as described below. Positive clones were further subcloned by limited dilution to create stable monoclonal antibody (mAb). All cell cultures were maintained in DMEM medium, supplemented with 5% fetal bovine serum, 2 mmol/L L-glutamine, and 1% penicillin-streptomycin (Invitrogen) in a humidified 5% CO2/95% air incubator at 37° C. Mouse mAb was purified from culture medium with goat anti-mouse IgG agarose (Invitrogen) and further characterized with mouse antibody isotyping kit (Zymed Laboratory).
1.1.1 ELISA Assay for Detecting TPA mAb Binding
To screen positive TPA binding clones, microplates were coated with 1-211 g/ml TPA in phosphate buffered saline (PBS, Invitrogen) for one hour at room temperature, followed by blocking with 1% bovine serum albumin (BSA, Invitrogen) in PBS for one hour. After that, mouse serum, hybridoma cell culture supernatant, or 2-5 μg/ml purified anti-TPA mAb in PBS solution was loaded and incubated for one hour. The bound mAb was detected by horse radish peroxidase (HRP) conjugated goat antimouse IgG (Santa Cruz Biotechnology, Inc,) with TMB substrate (3,3′,5,5′-tetramethylbenzidine (TMB) substrate, Pierce Plus activated HRP conjugation kit (Fisher Scientific)). In some runs, 3 μg/ml human PAI-1 was incubated in TPA coated BSA blocked wells before the addition of anti-TPA mAb to examine the binding between mAb and TPA-PAI-1 complex; complex formation was confirmed by detection of bound PAI-1 with mouse anti-human PAI-1 mAb. TPA and anti-TPA mAb binding constants were estimated by saturation binding experiment with ELISA assay. Briefly, 7.5 μg/ml purified anti-TPA mAb in PBS were coated on microplate for one hour at room temperature, followed by blocking with 1% BSA in PBS. Varying concentrations of human TPA (0-4 μg/ml) were then loaded in human serum pre-quenched with 20 μM PPACK (d-Phe-Pro-Arg chloromethylketone (PPACK) (Calbiochem)), and 200 kallikrein inhibitor units aprotinin. Bound TPA was detected with HRP-conjugated mouse anti-human TPA polyclonal antibody, followed by TMB substrate. The reaction was monitored at A370 nm within the dynamic range of the microplate reader. Binding constants were calculated using Graphpad Prism Software (La Jolla, Calif.). To test if anti-TPA mAb compete with each other for binding with TPA, 211 g/ml TPA was coated on microplates. After blocking with I % BSA in PBS, varying concentration of HRP-labeled anti-TPA mAb were added. After washing, the bound mAb were detected with TMB substrate. In some wells, varying concentrations of purified anti-TPA mAb was added to a fixed amount of HRP-labeled anti-TPA mAb to compete the binding for coated TPA. The percent inhibition of binding was calculated based on the difference between bound HRP labeled mAb in the absence and presence of purified anti-TPA mAb.
1.2. RNA Preparation from Hybridoma Cells
Mouse hybridoma cells generated according to 1.1 and identified as TPAi-1, were pelleted and washed with PBS. The pellet was processed using the Qiagen RNeasy Kit to isolate RNA following the manufacturer's protocol (Section 1.2.1).
1.2.1 RNeasy Mini Protocol for Isolation of Total RNA (Qiagen)
1.3. 1st Strand cDNA Synthesis
RNA (˜3 μg) was reverse-transcribed to produce cDNA using the GE Life Sciences 1st strand cDNA synthesis kit following the manufacturer's protocol (1.3.1). This was repeated twice to generate 3 independent cDNA products (rounds 1, 2 and 3) in order to detect and avoid cDNA mutations induced by the Reverse Transcriptase.
1.3.1 Protocol for 1st-Strand cDNA Synthesis (GE Life Sciences)
cDNA Purification: A simple protocol designed to remove contaminating First-Strand cDNA primer that could interfere with subsequent PCR reactions.
1.4. cDNA Sequence Determination
The cDNA was amplified by PCR in 3 separate reactions as described in 1.4.1. Immunoglobulin cDNA was PCR-amplified with kappa light chain primers plus MKC (
The result of each PCR reaction was a single amplification product that was purified using the QIAquick PCR purification kit (1.4.2) and sequenced (by GATC Biotech) in both directions using the M13-Forward and M13-Reverse primers (
1.4.1 PCR-Cloning of Mouse Variable Regions
Sterile water: Treat de-ionised, distilled water with DEPC (Sigma, D-5758) (final conc 0.1%) overnight at RT. Autoclave for 20 minutes at 115° C. and 15 p.s.i.
PCR-cloning primers (see
5×TBE buffer: (0.45M Tris-borate, pH8.3 10 mM EDTA.)
10×TAE buffer: (0.4M Tris-acetate, pH8.0, 10 mM EDTA.)
1.4.2 QIAquick PCR Purification Microcentrifuge and Vacuum Protocol (QIAGEN)
1.5. VK and VH DNA Sequence
The consensus sequence of hybridoma TPAi-1 VK, and the consensus DNA sequence of TPAi-1 VH, are shown in
2.1. VK and VH DNA Sequence
Germ Line Analysis of the TPAi-1 sequences show that the Kappa Light Chain is a Murine VK1, with two somatic mutations, both of which are in Framework 1 (
2.2. Construction of the Chimeric Expression Vectors
Construction of chimeric expression vectors entails cloning the amplified variable regions into IgG/kappa vectors (pHuG1 and pHuK—
The genes for TPAi-1 VH and VK were codon optimized for human sequences and synthesized by GenScript. The antibody sequences (
Several clones were isolated and colonies screened by PCR using primers HCMVi and HuG1 LIC Rev for VH or HuK LIC Rev for VK (
2.2.1 Generation of mAb Expression Vectors by LIC
2.2.1.1 Transformation of TOP10™ E. coli (Invitrogen Protocol)
2.2.2 Plasmid DNA Miniprep Isolation Using QIAprep® (Qiagen Protocol)
2.3. Generation of the Chimeric Antibodies
ExpiCHO suspension cells growing in ExpiCHO expression medium and antibiotics were co-transfected with TPAi-1 VH.pHuG1 and TPAi-1 VK.pHuK (1 μg DNA each) using ExpiFectamine-CHO Reagent (2.3.1). The cells were grown in 1 ml growth medium for 7 days. Up to 220 μg/ml of chimeric TPAi-1 antibody was measured in the conditioned medium by Octet with Protein G biosensors (2.3.2).
2.3.1 ExpiCHO Transfection in 24-Well Plates 1 ml Transfection
ExpiFectamine CHO kit 1 L (ThermoFisher Scientific cat. no. A29129)
OptiPRO SFM (ThermoFisher Scientific cat. no. 12309-050)
ExpiCHO Expression Medium (cat. no. A29100-01)
Day−1: Split Cells
Day 0: Transfection
Day 1: Add 6 ul ExpiCHO Enhancer and 190 ul ExpiCHO Feed 18-22 hours post-transfection.
Harvest: For Standard Protocol: Protein expression is typically complete and supernatant ready to be harvested by Day 7-8 post transfection.
2.3.2 Quantification of Human Antibodies by Octet Using Protein G Biosensors
At the end of the run, biosensors will be back in original positions.
To store sensors for re-use:
2.4 tPA Binding Activity of Chimeric Antibodies
Binding of the chimeric TPAi-1 antibody to recombinant human tPA (rh-tPA: abcam ab92637), recombinant mouse tPA (rm-tPA: abcam ab92715) and recombinant rat tPA (rr-tPA: abcam ab92596) was measured by ELISA and compared to the original mouse antibody 2.4.1). The chimeric and mouse TPAi-1 antibodies bound rh-tPA with comparable EC50 values (
2.4.1 tPA Binding ELISA
Add 100 μL to each well. Incubate 1 hour at RT and repeat washing step.
3.1. Human VH and VK cDNA Databases
The protein sequences of human and mouse immunoglobulins from the International Immunogenetics Database 2009 (Lefranc, 2015) and the Kabat Database Release 5 of Sequences of Proteins of Immunological Interest (last update 17 Nov. 1999)(Kabat et al. 1991) were used to compile a database of human immunoglobulin sequences in Kabat alignment.
3.2. Molecular Model of TPAi-1
A homology model of mouse TPAi-1 antibody variable regions was calculated using the Discovery Studio 4.1 program run in automatic mode. Sequence templates for the Light Chain and Heavy Chain variable regions were determined by Blast analysis of the Accelrys antibody pdb structures database. These templates were used to potential models.
3.3. Human Framework Selection
Humanisation requires the identification of suitable human V regions. The sequence analysis program, Gibbs, was used to interrogate the human VH and VK databases with TPAi-1 VH and VK protein sequences using various selection criteria. Using the program Discovery Studio (Accelrys), FW residues within 4 Å of the CDR residues (KABAT and IMGT definitions) in the structures of mouse TPAi-1 antibody were identified.
Human heavy chain donor candidates and human kappa light chain donor candidates were identified using various selection criteria.
3.4. Design of TPAi-1 Human Heavy Chain
The initial design of the humanised version of TPAi-1 was the grafting of CDR 1, 2 and 3 from TPAi-1 VH into the acceptor FW of a potential heavy chain donor candidate Potential sequences were assembled in silico.
3.5. Design of TPAi-1 Human Kappa Light Chain
CDR 1, 2 and 3 from TPAi-1 VK were grafted into the acceptor FW of potential human kappa light chain donor candidates to generate the potential version of humanised TPAi-1.
3.6. Remodelling of TPAi-1
The humanised TPAi-1 candidates were remodelled, including mutations, using various selection criteria.
4.1. Generation of TPAi-1 Humanised Antibodies
The genes for humanisedTPAi-1 candidates were synthesized by GenScript and codon optimized for human sequences. Using software algorithms proprietary to GenScript, the sequences were optimized by silent mutagenesis to use codons preferentially utilized by human cells and synthesized. Heavy chain and kappa light chain constructs were PCR amplified with specific primers to the expression vector+insert (as described previously for the chimeric versions) and inserted into pHuG1 and pHuK (
4.1.1 QuikChange Lightning Site-Directed Mutagenesis Kit (Stratagene)
4.1.2 Plasmid DNA Miniprep Isolation Using QIAprep® (Qiagen Protocol)
4.1.3 Qiagen Protocol for Plasmid DNA Maxi Prep
4.2. Antibody Expression
The concentrations of IgG1κ antibodies in ExpiCHO cell conditioned media were measured by Octet using Protein G biosensors (2.3.2).
Examples of humanised TPAi-1 antibodies are shown in Table 1.
4.3. Antigen Binding by the Humanised TPAi-1 Antibodies
Binding activity to the tPA antigen was measured by Binding ELISA (2.4.1). The data shown in
4.4. Determination of Humanised Candidate Antibodies Tm (Melting Temperature)
In order to determine the melting temperature antibodies TPAi-1 RHE/RKA and TPAi-1 RHP/RKA, these antibodies were tested in a thermal shift assay. Samples were incubated with a fluorescent dye (Sypro Orange) for 71 cycles with 1° C. increase per cycle in a qPCR thermal cycler. Tm values for the two humanised antibodies are indicated in
4.5. Aggregation Analysis of Humanised Candidate Antibodies
Aggregation assessment of the TPAi-1 RHE/RKA and TPAi-1 RHP/RKA antibodies was carried out by dynamic light scattering (DLS). The antibodies were found to have hydrodynamic radii and polydispersity consistent with monomer (
4.6. Non-Specific Protein-Protein Interactions (CIC)
Cross-Interaction Chromatography using bulk purified human polyclonal IgG is a technique for monitoring nonspecific protein-protein interactions, and can be used to discriminate between soluble and insoluble antibodies.
An elevated Retention Index (k′) indicates a self-interaction propensity and a low solubility. Both candidate antibodies show a Retention Index below 0.05, indicating a low propensity for non-specific interactions and good solubility (
4.7. Solubility of Humanised Candidate Antibodies
The purified candidate antibodies were concentrated using solvent absorption concentrators (MWCO 7500 kDa) and the concentration measured at timed intervals. Both samples were concentrated to more than 40 mg/ml without apparent precipitation (
4.8. Freeze/Thaw Stress Analysis of Candidate Antibodies
Samples of the purified RHE/RKA and RHP/RKA antibodies were subjected to 10 cycles of 15 minutes at −80° C. followed by thawing for 15 minutes at Room Temperature. Control samples were kept at 4° C. throughout. The samples were then analysed by SEC-MALS for aggregation (
4.9. Heat-Induced Stress Analysis of Candidate Antibodies
Samples of the purified RHE/RKA and RHP/RKA antibodies were heat exposed at a) Room Temperature, b) 37° C. and C) 50° C. or kept at 4° C. for 30 days. Samples were then analysed by SEC-MALS for aggregation (
4.10 Serum Stability Assessment of Candidate Antibodies
Purified samples of humanised antibodies TPAi-1 RHE/RKA and RHP/RKA were incubated in mouse, human and cynomolgus serum (4.10.1). The binding abilities of the antibodies after 29 days incubation were measured by binding ELISA to human tPA. For each antibody, one ELISA plate compared the binding of the 4° C. control sample to samples incubated at 37° C. in PBS and human serum. A second ELISA plate compared the binding of the 4° C. control sample to samples incubated at 37° C. in mouse and cynomolgus serum. The graphs of
4.10.1 Antibody Serum Stability Assessment
Samples: 600 μl at 0.4 mg/mL of polished antibody in PBS (240 μg)
Test conditions: Mouse serum (SCD-808), Human serum (S-123) and Cyno serum (S-118) from Seralab
5.1. Generation of TPAi-1 RHP/RKA Fab
The DNA for the heavy chain variable region of TPAi-1 RHP/RKA was amplified from the IgG1 expression construct TPAi-1_RHP.pHuG1 using primers containing the 3′ end of the leader sequence (most of the sequence is present in the vector)—forward primer—or the beginning of the constant region (IgG1)—reverse primer—, followed by the beginning of the variable region (in each direction),
5.2. TPAi-1 RHP/RKA Fab Expression
The concentration of TPAi-1 RHP/RKA Fab in the Expi293 cell conditioned medium was measured at 102 μg/ml by Octet, using Streptavadin biosensors coated with an anti-human kappa chain reagent (5.2.1). Larger-scale transfection and culture yielded 72 mg purified Fab from 1 L conditioned medium.
4.10.1 Quantification of Human Fab by Octet Using Anti-Kappa Light Chain-Coated Sensors
Streptavadin (SA) biosensors (18-5020) were coated with CaptureSelect™ Biotin Anti-LC-Kappa (Hu) Conjugate (13 kDa Llama antibody fragment; 7103272100, ThermoScientific) by carrying out a 15 min loading step with the reagent diluted to 5 μg/mL in HBS-P+buffer. The coated biosensors were subjected to 3 regeneration cycles of 10 mM glycine pH2.0 (15 s)/HBS-P+buffer (15 s), soaked in 15% sucrose solution for 10 min and allowed to airdry.
These sensors were used to quantify the concentration of Fab in supernatant samples by following the procedure of section 2.3.2 but using the template file ‘FAb Quantification (Capture Select Anti-Kappa LC)’. Purified control human Fab was used as the standard.
5.3. Antigen Binding by TPAi-1 RHP/RKA Fab
Binding activity of the TPAi-1 RHP/RKA Fab to the human tPA antigen was compared to that of the purified TPAi-1 RHP/RKA antibody in a binding ELISA. The initial experiment used RHP/RKA Fab in the form of Expi293 cell conditioned medium and showed dose-dependent binding of the Fab to human tPA (
5.4. Determination of TPAi-1 RHP/RKA Fab Tm (Melting Temperature)
A thermal shift assay was used to determine the melting temperature of the TPAi-1 RHP/RKA Fab (24). The Tm for TPAi-1 RHP/RKA Fab is 74° C. and the Fab therefore passes thermal stability requirements.
5.5. Aggregation Analysis of TPAi-1 RHP/RKA Fab
TPAi-1 RHP/RKA Fab was injected at 0.4 mL/min into a size exclusion column in an HPLC system and analysed by multi-angle light scattering to determine the absolute molar mass and check for aggregation (see
5.6. Non-Specific Protein-Protein Interactions of TPAi-1 RHP/RKA Fab (GIG)
Cross-Interaction Chromatography using bulk purified human polyclonal IgG is a technique for monitoring nonspecific protein-protein interactions, and can be used to discriminate between soluble and insoluble antibodies. An elevated Retention Index (k′) indicates a self-interaction propensity and a low solubility. TPAi-1 RHP/RKA Fab shows a Retention Index below 0.05, indicating a low propensity for non-specific interactions and good solubility (
5.7. Solubility of TPAi-1 RHP/RKA Fab
The purified TPAi-1 RHP/RKA Fab was concentrated using a solvent absorption concentrator (MWCO 7500 kDa) and the concentration measured at timed intervals. The sample was concentrated to more than 65 mg/ml without apparent precipitation (
5.8 Freeze/Thaw Stress Analysis of TPAi-1 RHP/RKA Fab
A sample of the purified RHP/RKA Fab was subjected to 10 cycles of 15 minutes at −80° C. followed by thawing for 15 minutes at Room Temperature. A control sample was kept at 4° C. throughout. The samples were then analysed by SEC-MALS for aggregation (
5.9 Heat-Induced Stress Analysis of TPAi-1 RHP/RKA Fab
Samples of the purified RHP/RKA Fab were heat exposed at a) Room Temperature, b) 37° C. and C) 50° C. or kept at 4° C. for 30 days. Samples were then analysed by SEC-MALS for aggregation (
5.10 Serum Stability Assessment of TPAi-1 RHP/RKA Fab
Purified samples of TPAi-1 RHP/RKA Fab were incubated in mouse, human and cynomolgus serum (4.10.1). The binding abilities of the antibodies after 29 days incubation were measured by binding ELISA to human tPA (
Conversion of TPAi-1 RHP/RKA from a whole IgG to Fab format resulted in a loss of binding avidity for human tPA in the binding ELISA (Section 5.3;
6.1 Preparation of TPAi-1 RHP/RKA F(Ab′)2
5 mg TPAi-1 RHP/RKA IgG1κ antibody was digested with pepsin and the sample analysed by SDS-PAGE to confirm digestion and presence of molecules of the expected size for an F(ab′)2 (non-reduced MW˜110 kDa;
6.2. Aggregation Analysis of TPAi-1 RHP/RKA F(Ab′)2
TPAi-1 RHP/RKA F(ab′)2 was injected at 0.4 mL/min into a size exclusion column in an HPLC system and analysed by multi-angle light scattering to determine the absolute molar mass and check for aggregation (
6.3. Antigen Binding by TPAi-1 RHP/RKA F(Ab′)2
Binding activity of the purified TPAi-1 RHP/RKA F(ab′)2 to the human tPA antigen was compared to that of the purified TPAi-1 RHP/RKA whole IgG1 antibody and RHP/RKA Fab in a binding ELISA. The binding curves of the RHP/RKA whole IgG1 and F(ab′)2 are very similar, with EC50 values of 0.475 nM and 0.379 nM, respectively (
The comparable binding of the whole IgG and F(ab′)2 forms of TPAi-1 RHP/RKA shows that removal of the IgG1 Fc region does not affect avidity for human tPA. Thus the lower avidity exhibited by the TPAi-1 RHP/RKA Fab is entirely due to the change from bivalent to monovalent binding.
7.0 Assays of TPA Activity
The amidolytic activity of TPA was examined with 500 μM chromogenicsubstrate S2288. Pg activation by TPA was determined by monitoring the amidolytic activity of plasmin with 500 μM S2251. All experiments were performed at 37° C. in Tris-NaCl buffer (50 mM Tris-HCl, 100 mM NaCl, pH 7.4) as described previously (Sazonova I Y, McNamee R A, Houng A K, King S M, Hedstrom L, Reed G L. Reprogrammed streptokinases develop fibrin-targeting and dissolve blood clots with more potency than tissue plasminogen activator. J Thromb Haemost. 2009; 7: 1321-1328). Pg was pretreated with aprotinin-agarose beads for four hours at 4° C. to remove contaminating plasmin. In both assays, the absorbance at 405 nm (A405 nm) was continuously recorded. The amidolytic activity of TPA was determined from the initial slope of A405 nm with time. The activation rate of Pg by TPA to plasmin was calculated using the change in A405 nm per second squared over the initial period of reaction when net change of absorbance was less than 0.1, based on the method described by Longstaff et al. Longstaff C, Whitton C M. A proposed reference method for plasminogen activators that enables calculation of enzyme activities in SI units. J Thromb Haemost. 2004; 2: 1416-1421. In some runs, anti-TPA mAb or fibrin (Fn) fragment was incubated with TPA to examine their effect on TPA activity or Pg activation.
8.0 Fibrinolysis
Human clots were formed by mixing 20 μl human plasma (with trace amount of 125I-fibrinogen) with 5μ1 mixture of thrombin and calcium solution (final concentration: 1 Ul/ml thrombin and 10 mM Ca2+ in test tube. The clot was incubated at 37° C. for one hour, followed by the addition of total 45 μl of varying amounts of human TPA with or without anti-TPA mAb. At sampling time, 10 μl supernatant was collected and the radioactivity of this sample was monitored using Cobra II gamma counter (Perkin-Elmer—Packard BioScience, Waltham, Mass.). After gamma counting, the samples were replaced in the test tube. The percent fibrinolysis was determined by the radioactivity in the supernatant divided by the initial clot radioactivity. The percent inhibition of fibrinolysis by mAbs was calculated by reference to the amount of fibrinolysis in the absence of mAbs.
Both chimeric TPAi-1 and humanized TPAi-1 (TPAi-1 RHP/RKA) significantly inhibited the dissolution of human clots induced by human TPA (
TPAi-1 RHP/RKA Fab was also tested for its effects to inhibit plasma clot lysis in a dose response manner. Human plasma clots were formed by mixing together pooled fresh frozen (3.8% Sodium citrate) human plasma (50 μl), calcium and thrombin (10 μl), t-PA (10 μl, 1.5 nM) and purified mouse, chimeric, humanized mAb and the humanised Fab (0-140 nM). The dissolution or lysis of clots was monitored continuously at 37 deg. C. in a microtiter plate reader at A405 nm. The percentage of Lysis inhibition was determined by comparing (turbidity) the absorption reading at A405 nm at Baseline and at 1 hour. As seen in
9.0 Mouse Middle Cerebral Artery Thromboembolic Stroke and Bleeding
Animal studies that were performed in Dr. Reed's laboratory were approved by the UT-Memphis Institutional Animal Care and Use Committee. C57BL/6J adult mice (29 to 35 g, Jackson Lab, Bar Harbor Me.) were anaesthetized with a mixture of 1.5-2% isoflurane and oxygen administered throughout the study. Rectal temperature was maintained at 3TC with a thermostat controlled heating pad. The left common carotid artery was isolated after a neck incision, and the external carotid, thyroid, and occipital arteries were ligated. Microvascular clips were temporarily placed on the common carotid and internal carotid arteries. A small arteriotomy was made on the external carotid artery for retrograde insertion of the PES catheter containing emboli 125I-fibrinogen (˜5000 cpm/2 ul). The PES tubing containing the clots were inserted into the left external carotid artery, threaded into the internal cerebral artery up to origin of the middle cerebral artery (MCA). The thrombus was embolized at a speed of 0.45 ml/min in a volume of 100 ul saline. Continuous laser-Doppler monitoring was used to assess regional cerebral perfusion to ensure adequacy of embolization (perfusion decreased to <20% of pre-ischemic baseline). The right jugular vein was cannulated for drug administration. Mice received recombinant human TPA (rtPA) (10 mg/kg at 2.5 hr of ischemia) as a 20% bolus, 80% infusion over 30 minutes. Mice receiving mAb inhibitors were treated by stoichiometric dose of the murine, chimeric and humanized monoclonal antibodies given as an intravenous bolus 30 or 60 minutes after the TPA administration. Tail bleeding was assessed at 20 minutes after the TPA infusion and monitored for 30 minutes by measuring the time and amount of bleeding from tails pre-warmed for 5 mins in 3 mL of saline at 37° C. in a water bath as described. Hemoglobin (Hgb) loss from tail bleeding was measured using Drabkin's reagent kit according to manufacturer's data sheet (Sigma). Six hours after thromboembolism the animals were killed, the brain was isolated, cut into 2-mm coronal sections, and incubated in 2% triphenyltetrazolium chloride (Sigma, St. Louis, Mo.) solution for 30 mins at room temperature. The stained slices then were transferred into 4% formaldehyde for fixation. Images of four brain sections were captured with digital camera. The hemispheric size, area of gross hemorrhage and infarction area were digitally analyzed using Image Pro Plus 6.2 software and a modified Swanson's method (Swanson R A, Morton M T, Tsao-Wu G, Savalos R A, Davidson C, Sharp F R. A semi-automated method for measuring brain infarct volume. J Cereb Blood Flow Metab. 1990; 10:290-293). The amount of clot lysis was determined by comparing the residual thrombus radioactivity in the brain to that of the initial clot.
9.1 Limiting the Duration of r-tPA-Induced Plasminogen Activation Reduced Brain Injury and Bleeding
The potent, specific effects of TPAi-1 allowed examination of whether the persistence of r-tPA-induced plasminogen activation is harmful during prolonged brain ischemia in a thromboembolic model with translational relevance to human stroke. Mice were randomly assigned to receive placebo, murine TPAi-1, chimeric TPAi-1 or humanized TPAi-1 (TPAi-1 RHP/RKA) thirty or sixty minutes following r-tPA bolus therapy, which was given 2.5 hours after middle cerebral artery thromboembolism. In these mice, bleeding following tail transection (under anesthesia) was monitored as an indicator of arterial and venous surgical hemorrhage related to persistent plasminogen activation. By comparison to mice receiving placebo, mice given murine TPAi-1 thirty or sixty minutes after r-tPA bolus, showed significant reductions in tail bleeding (
Treatment with r-tPA 2.5 hours after the onset of stroke was associated with significant brain hemorrhage (
The murine TPAi-1 (m), as well as the chimeric (c) and the humanized Mab (h) (TPAi-1 RHP/RKA) decreased the amount of brain hemorrhage.
When compared to control mice, treatment with mTPAi-1 either 30 or 60 min. after initial r-tPA therapy significantly reduced brain infarction. There was also a significant reduction in brain infarction when mice are treated with either mtPAi-1 or htPAi-1 (TPAi-1 RHP/RKA) thirty minutes after initial tPA therapy. (
10.0. Binding of Chimeric TPAi-1, Humanised TPAi-1 (RHP/RKA) and TPAi-1 (RHP/RKA) Fab to the TPA Mutant Tenecteplase
The binding activity to the TPA mutant tenecteplase (TNK) was measured by Binding ELISA (2.4.1). The binding of the Fab (TPAi-1 RHP/PKA Fab) to Tenecteplase was compared to that of the chimeric mAb TPAi-1, and the humanised mAb TPAi-1 RHP/RKA and a control Fab (
All publications, patents and patent applications herein are incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom as modifications will be obvious to those skilled in the art. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed inventions, or that any publication specifically or implicitly referenced is prior art. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth and as follows in the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1818477.0 | Nov 2018 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2019/081225 | 11/13/2019 | WO | 00 |
