Patent Grant
8722618
The subject matter of this application was developed under a joint research agreement between Centocor Research & Development, Inc. and Molecular Partners AG, effective Dec. 21, 2007.
The present invention relates to recombinant binding proteins comprising a binding domain which is a repeat protein comprising designed modular repeat units and selected for the ability to inhibit the binding of IL4 and IL13 to their cognate receptors thereby representing useful and stable therapeutic proteins. More particularly, the present invention is directed to bi-specific IL4/IL13 binding proteins comprising ankyrin repeat modules.
Interleukin 4 (human IL4, UniProt P05112) is a 129 amino acid cytokine derived from T cells and mast cells with multiple biological effects on many cell types including B-cells, T-cells and nonlymphoid cells including monocytes, endothelial cells and fibroblasts. IL4 is a pleiotropic cytokine and has been implicated in many of the cellular responses associated with asthma including IgE production, inflammation, airway hypersensitivity, and goblet cell hyperplasia (Perkins, et al., J Allergy Clin Immunol 118: 410-9, 2006; Pene, et al., Proc Natl Acad Sci USA 85: 6880-4, 1988). Its production by both T-cells and mast cells is regulated by a variety of mediators and cytokines that sustain Th2-mediated responses. IL4 signaling is mediated via two receptor complexes, the Type I receptor complex and the Type II receptor complex. Signaling through the type II receptor complex, composed of one IL-4Rα and one IL13Rα1 chain, is largely responsible for the shared biological effects of IL4 and IL13 and both IL4 and IL13 may contact the components of the complex. The type I receptor complex, comprised of the IL-4Rα and common γ-chain is, exclusively responsive to IL4 and mediates IL4 responses in T-cells which do not express IL13αR1 (Idzerda, et al., J Exp Med 171: 861-73, 1990; Nelms, et al., Annu Rev Immunol 17: 701-38, 1999).
Neutralizing the effects of IL4 using antibodies or as demonstrated by the responses of IL4 deficient mice, inhibits allergen-specific IgE and reduces eosinophilia (Zhu and Paul, Blood 112: 1557-69, 2008), as well as airway hyperresponsiveness (AHR) (Heaton, et al., Lancet 365: 142-9, 2005) in murine models of TH2 inflammation. Similarly, soluble IL4 receptor has been used to inhibit IL4 signaling and has been shown to reduce allergen-induced AHR as well as VCAM-1 expression, mucus production and eosinophil recruitment to the lungs of mice (McKinley, et al., J Immunol 181: 4089-97, 2008). In human cells, IL4 has been shown to drive the differentiation of naïve T helper (Th0) lymphocytes into TH2 lymphocytes (Breekveldt-Postma, et al., Curr Med Res Opin 24: 975-83, 2008; Wraight, et al., Respirology 7: 133-9, 2002). TH2 cells have been shown to secrete IL-4, IL-5, IL-9 and IL13 but do not produce IFNγ, contributing to an imbalance of pro-inflammatory TH2 cytokines (Partridge, Ann Oncol 17: 183-4, 2006). Neutralization of IL4 with antibodies that inhibit receptor binding blocks T-cell differentiation ((Idzerda, et al., J Exp Med 171: 861-73, 1990; Nelms, Keegan et al., Annu Rev Immunol 17: 701-38, 1999)). Polymorphisms in the genes encoding IL4, IL4Ra, and IL13 have been associated with asthma, in fact, both IL4 and IL4Rα polymorphisms are associated with severe asthma and exacerbations of asthma (Sandford, et al., J Allergy Clin Immunol 106: 135-40, 2000; Wenzel, et al., Am J Respir Crit Care Med 175: 570-6, 2007). Based on the perceived central role of IL4 in asthma, biotherapeutics that inhibit the activity of IL4 were expected to be valuable tools for the treatment of asthma and other Th2-associated pathologies. However the results of clinical studies using a soluble IL4 receptor were disappointing and showed minimal differences in the incidence of asthma exacerbations between placebo and treatment groups (Borish, et al., J. Allergy Clin. Immunology 107: 963-70, 2001).
Like IL4, Interleukin 13 (IL13) is cytokine identified from activated human T lymphocytes. Over the last 10 years, a variety a reports have demonstrated a role for IL13 in many of the cellular responses associated with asthma including IgE production, inflammation, airway hypersensitivity, mucus production and lung fibrosis (Kasaian and Miller, Biochem Pharmacol 76: 147-55, 2008). Its production is regulated by a variety of mediators and cytokines that interact in a positive feedback loop to sustain Th2-mediated immune responses. IL13 signaling is predominantly mediated via the Type 2 receptor, IL13α1 and IL-4Rα complex. The Type 2 complex, when present, is also activated by IL4 binding (Wills-Karp, Immunological Reviews 202: 175-90, 2004; LaPorte, et al., Cell 132: 259-72, 2008). IL13Ralpha2, is a receptor capable of high affinity binding of IL13 and may play a more functional role either by attenuation of the actions of IL13 and IL4 or via induction of TGF-beta and development of lung fibrosis.
A variety of in vivo data supports a role for IL13 in the pathogenesis of asthma. In cynomologus monkey models of allergic respiratory disease, antibodies that block the action of IL13 have been shown to reduce lung inflammation (Kasaian, et al., J Pharmacol Exp Ther 325: 882-92, 2008). In humans, increased IL13 levels can be measured in the bronchial tissue, nasal lavage flurid, and induced sputum from asthmatic patients. Genetic polymorphisms that are associated with asthma have been identified at the IL13 locus (Heinzmann, et al., Hum Mol Genet. 9: 549-59, 2000). In addition, IL13 appears to play an important role in other atopic diseases including dermal fibrosis and atopic dermatitis. Antibodies or other protein molecules that inhibit the activity of IL13 may be valuable therapeutics for the treatment of asthma and other atopic diseases (Brightling, et al., Clin Exp Allergy 40: 42-9).
Taken together, the in vivo and in vitro data for IL13 and IL4 suggest that therapeutics that can inhibit the actions of both cytokines may be efficacious agents for the treatment of asthma.
The technical problem underlying the present invention is to identify novel IL-4 and IL-13 antagonists (e.g., neutralizing binders) which can be used alone or in combination for an improved treatment of inflammatory disorders, cancer, atopic diseases and other pathological conditions associated with allergic or atopic responses, e.g., asthma, eosinophilia, and fibrotic conditions and where pulmonary functions are affected, to provide for local delivery of an IL4, IL-13, or an IL4 and IL13, neutralizing molecule.
The present invention relates to binding protein constructs comprising IL4/IL13-binding ankyrin repeat (AR) proteins capable of binding IL4 and IL13 and that inhibit bioactivity of IL4 and IL13. An IL4 and IL13 inhibiting construct as exemplified herein is comprised of an IL4-binding AR repeat domain linked to an IL13-binding AR repeat domain. Such bispecific AR proteins have application as biotherapeutics for a variety of Th2 mediated diseases, including asthma and other atopic diseases associated with the presence or bioactivity of IL4 and IL13.
The present invention also relates to binding protein constructs comprising IL4 or IL13-binding ankyrin repeat (AR) proteins capable of binding IL4 or IL13 and that inhibit bioactivity of IL4 or IL13. An IL4 or IL13 inhibiting construct as exemplified herein is comprised of an IL4-binding AR repeat domain or an IL13-binding AR repeat domain. Such bispecific AR proteins have application as biotherapeutics for a variety of Th2 mediated diseases, including asthma and other atopic diseases associated with the presence or bioactivity of IL4 or IL13.
The invention further relates to nucleic acid molecules encoding the recombinant binding proteins of the present invention, and to a pharmaceutical composition comprising one or more of the binding proteins or nucleic acid molecules.
The invention further relates to a method of treatment of inflammatory diseases, cancer, atopic diseases and other pathological conditions, especially pulmonary conditions, such as asthma and those conditions leading to pulmonary fibrosis, using the binding proteins of the invention. In a particular embodiment, the binding proteins capable of IL4-binding or IL13-binding, alone or in combination may be used in methods of prophylactic or therapeutic treatment to prevent, ameliorate, reduce or eliminate the symptoms or pathophysiology of IL4 and/or IL13 mediated disease. A particular method of treatment is by local delivery of an IL4-binding protein and/or IL-13-binding protein of the invention. In one embodiment of the method of treatment, the IL4-binding protein and/or IL-13-binding protein is administered as an aerosolized formulation. In one method of local delivery, the aerosolized formulation comprising an IL4-binding protein and/or IL-13-binding protein is administered to pulmonary compartment of the subject in need of treatment. The method of treatment is provided to a subject, as prophylactic or therapeutic treatment comprising the IL4-binding protein and/or IL-13-binding protein where the subject is diagnosed or suspected of having a condition, such as asthma, an inflammatory disorder, cancer, atopic disease, or other pathological conditions associated with allergic or atopic responses, e.g., eosinophilia, and fibrotic conditions and, especially, where pulmonary functions are affected.
CCL17=chemokine (CC-motif) ligand 17; ECD=extracellular domain; IL=interleukin; TARC=Thymus and Activation-Regulated Chemokine; PBS=phosphate buffered saline; AR=ankyrin repeat; MEM=Minimum Essential Media, NEAA=Non-Essential Amino Acids, SPR surface plasmon resonance.
The term “protein” refers to a polypeptide, wherein at least part of the polypeptide has, or is able to; acquire a defined three-dimensional arrangement by forming secondary, tertiary, or quaternary structures within and/or between its polypeptide chain(s). If a protein comprises two or more polypeptides, the individual polypeptide chains may be linked non-covalently or covalently, e.g. by a disulfide bond between two polypeptides. A part of a protein, which individually has, or is able to acquire a defined three-dimensional arrangement by forming secondary or tertiary structures, is termed “protein domain.” Such protein domains are well known to the practitioner skilled in the art.
In the context of the present invention, the term “polypeptide” relates to a molecule consisting of multiple, i.e., two or more, amino acids linked via peptide bonds. Preferably, a polypeptide consists of more than eight amino acids linked via peptide bonds.
The term “binding protein” refers to a protein comprising one or more binding domains. In various embodiments of the invention, the binding protein comprises two, three, or four binding domains. Furthermore, any such binding protein may comprise additional protein domains that are not binding domains, multimerization moieties, polypeptide tags, polypeptide linkers and/or a single Cys residue. Examples of multimerization moieties are immunoglobulin heavy chain constant regions which pair to provide functional immunoglobulin Fc domains, and leucine zippers or polypeptides comprising a free thiol which forms an intermolecular disulfide bond between two such polypeptides. Free thiol, residing on e.g. a Cys residue, may be used for conjugating other moieties to the polypeptide, for example, by using the maleimide chemistry well known to the person skilled in the art. Preferably, said binding protein is a recombinant binding protein. Also preferably, the binding domains of the binding protein of the invention possess different target specificities. Non-proteinaceous atoms, such as metals; actives, and non-proteinaceous material may be attached or associated with the binding protein of the invention in a useful composition.
The term “binding domain” as used herein, means a protein domain exhibiting the same or substantially the same “fold” (three-dimensional arrangement) as a protein scaffold and having a specified property, such as binding a target molecule. A protein scaffold will have exposed surface areas in which amino acid insertions, substitutions or deletions are highly tolerable which may be modified to provide a binding domain with a selected, specified or determined property. Other specified properties of a binding domain may include: binding to a target, blocking of target binding or target activity, activation of a target-mediated reaction, enzymatic activity, and related further properties. Depending on the type of desired property, one of ordinary skill will be able to identify and perform the necessary steps for screening and/or selection of a binding domain with the desired property. Such a binding domain may be obtained by rational, or most commonly, combinatorial protein engineering techniques, skills which are known in the art (Skerra, A., J. Mol. Recog. 13, 167-187, 2000; Binz, H. K., Amstutz, P. and Plückthun, A., Nat. Biotechnol. 23, 1257-1268, 2005). For example, a binding domain having a selected property can be obtained by a method comprising the steps of (a) providing a diverse collection of protein domains exhibiting the same fold as a protein scaffold as defined further below; and (b) screening said diverse collection and/or selecting from said diverse collection to obtain at least one protein domain having said property. The diverse collection of protein domains may be provided by several methods in accordance with the screening and/or selection system being used, and may comprise the use of methods well known to the person skilled in the art, such as phage display or ribosome display libraries.
As described herein, the binding domain is a “repeat domain” or a “designed repeat domain.” Such a repeat domain may comprise one, two, three or more internal repeat modules that will participate in binding to a target or other specified property. Preferably, such a repeat domain further comprises an N-terminal capping module, two to four internal repeat modules, and a C-terminal capping module. Preferably, said binding domain is an ankyrin repeat domain or designed ankyrin repeat domain where the repeat modules sequences are from naturally proteins (repeat units) or are derived from consensus sequences of the natural repeat units (repeat modules). Thus, a repeat domain can be naturally occurring or can be formed, such as those obtained as the result of the inventive procedure explained in patent publication WO 02/20565.
A binding protein according to the invention may be a “repeat protein” or “designed repeat protein” which refers to a protein comprising two or more consecutive repeat units or modules (
The term “repeat unit” refers to amino acid sequences comprising repeat sequence motifs of one or more naturally occurring repeat proteins, wherein said “repeat units” are found in multiple copies, and which exhibit a defined folding topology common to all said motifs determining the fold of the protein. Such repeat units comprise framework residues and interaction residues. Examples of such repeat units are armadillo repeat units, leucine-rich repeat units, ankyrin repeat units, tetratricopeptide repeat units, HEAT repeat units, and leucine-rich variant repeat units. Naturally occurring proteins containing two or more such repeat units are referred to as “naturally occurring repeat proteins.” The amino acid sequences of the individual repeat units of a repeat protein may have a significant number of mutations, substitutions, additions and/or deletions when compared to each other, while still substantially retaining the general pattern, or motif, of the repeat units.
The term “repeat modules” refers to the repeated amino acid sequences of designed repeat proteins or domains. Each repeat module comprised in a repeat domain is derived from one or more repeat units of one family of naturally occurring repeat proteins where the members of said group comprise similar repeat units. Such “repeat modules” may comprise positions with amino acid residues present in all copies of the repeat module (“fixed positions”) and positions with differing or “randomised” amino acid residues (“randomised positions”). Examples of such repeat modules are armadillo repeat modules, leucine-rich repeat modules, ankyrin repeat modules, tetratricopeptide repeat modules, HEAT repeat modules, and leucine-rich variant repeat modules. The amino acid sequences of the individual repeat units/repeat modules of a repeat protein may have a significant number of mutations, substitutions, additions and/or deletions when compared to each other, while still substantially retaining the general pattern, or motif, of the repeat units/repeat modules.
The term “set of repeat modules” refers to the total number of repeat modules present in a repeat domain. Such “set of repeat modules” present in a repeat domain comprises two or more consecutive repeat modules, and may comprise just one type of repeat module in two or more copies, or two or more different types of modules, each present in one or more copies. In the set of repeat modules, the order of the modules determines the composition of the repeat domain and, where a repeat domain has been selected for a specific activity, the repeat domain biological function, such as a binding domain. The repeat units/modules in a repeat domain will herein be numbered consecutively from the N-terminus of the polypeptide to the C-terminus of the polypeptide.
The term “repeat sequence motif” refers to an amino acid sequence, which is deduced from one or more repeat units or repeat modules. Such repeat sequence motifs comprise framework residue positions and target interaction residue positions. Said framework residue positions correspond to the positions of framework residues of the repeat units (or modules). Likewise, said target interaction residue positions correspond to the positions of target interaction residues of the repeat units (or modules). The target interaction residues will generally be positioned along one face of the repeat domain. An example of such a repeat sequence motif is an ankyrin repeat sequence motif, such as shown in SEQ ID NO: 1.
The term “framework residues” relates to amino acid residues of the repeat units, or the corresponding amino acid residues of the repeat modules, which contribute to the folding topology, i.e., which contribute to the fold of said repeat unit (or module) or which contribute to the interaction with a neighboring unit (or module). Such contribution might be the interaction with other residues in the repeat unit (module), or the influence on the polypeptide backbone conformation as found in α-helices or β-sheets, or amino acid stretches forming linear polypeptides or loops.
The term “target interaction residues” refers to amino acid residues of the repeat units, or the corresponding amino acid residues of the repeat modules, which may contribute to the interaction of the repeat unit (or module) with a target substance. Such contribution might be the direct interaction with the target substances, or the influence on other directly interacting residues, e.g., by stabilizing the conformation of the polypeptide of a repeat unit (or module) to allow or enhance the interaction of directly interacting residues with said target. Such framework and target interaction residues may be identified by analysis of the structural data obtained by physicochemical methods, such as X-ray crystallography, NMR and/or CD spectroscopy, or by comparison with known and related structural information well known to practitioners in structural biology and/or bioinformatics.
Preferably, the repeat units/modules used for the deduction of a repeat sequence motif are homologous repeat units, wherein the repeat units comprise the same structural motif and wherein more than 70% of the framework residues of said repeat units are identical to each other. Preferably, more than 80% of the framework residues of said repeat units are identical. Most preferably, more than 90% of the framework residues of said repeat units are identical. Computer programs to determine the percentage of identity between polypeptides, such as Fasta, Blast or Gap, are known to the person skilled in the art. More preferably, the repeat units used for the deduction of a repeat sequence motif are homologous repeat units obtained from repeat domains selected on a target, for example, as described in Example 1, and having the same target-specificity.
Repeat sequence motifs comprise fixed positions and randomized positions. The term “randomized position” refers to an amino acid position in a repeat sequence motif, wherein two or more amino acids are allowed at said amino acid position, for example, wherein any of the usual twenty naturally occurring amino acids are allowed, or wherein most of the twenty naturally occurring amino acids are allowed, such as amino acids other than cysteine, or amino acids other than glycine, cysteine and proline. These amino acids may be in modified form as known in the art. Most often, such randomized positions correspond to the positions of target interaction residues. However, some positions of framework residues may also be randomized.
The term “capping module,” “capping unit” or “N-Cap” (for an N-terminal capping module) or “C-Cap” (for a C-terminal capping module) refers to a polypeptide fused to the N- or C-terminal repeat module of a repeat domain, wherein said capping module forms tight tertiary interactions with the adjacent repeat unit thereby providing a cap that shields the hydrophobic core of said repeat module at the side not in contact with the consecutive repeat module from the solvent. Said N- and/or C-terminal capping module may be, or may be derived from, a capping unit or other domain found in a naturally occurring repeat protein adjacent to a repeat unit. The N- or C-Cap forms tight tertiary interactions with the adjacent repeat unit. Such capping units may have sequence similarities to the repeat sequence motif. Capping modules and capping repeats are described in WO 02/020565 and exemplified herein.
The term “target” refers to a molecule, polypeptide or protein, carbohydrate, complexes of two or more molecules, which may exist in isolated form or reside in a biological form, such as on or in a cell or a tissue sample and may exist in multiple forms, such as naturally occurring or non-naturally occurring chemical modifications, for example, modified by phosphorylation, acetylation, or methylation, or exhibiting damage or cross-linked residues such as may occur upon reaction with ionizing radiation or reactive oxygen species caused be natural or non-natural processes. In the particular application of the present invention, the target is a soluble protein which is a cytokine.
By IL4, IL-4, or hIL4, is meant a small cytokine, human Interleukin 4 (UniProt P05112, SEQ ID NO: 4) or a species homolog thereof. Where specifically stated, the species homolog sequence is specified, e.g. cynomolgous monkey IL4, cyno IL4, or cIL4 (SEQ ID NO: 5). The protein is also known as B-cell stimulatory factor 1, B-cell growth factor, BCGF1, BCGF-1, BSF1, BSF-1, and Lymphocyte stimulatory factor 1, among other names. The human mature protein is expressed as a 153 amino acid polypeptide (UniProt P05112) with a 24 amino acid signal peptide, a single N-linked glycosylation site, and is cleaved to produce a 129 amino acid mature protein (SEQ ID NO: 1) with three interchain disulfide bonds. Two types of IL4 receptor exist: Type 1 and Type 2. Type 1 is a heterodimer consisting of the IL4 R-alpha (IL4 RA, CD124, UniProt P24394 and where SEQ ID NO: 6 represents the ECD thereof) and the common receptor subunit gamma, CD132 (IL2RG, UniProt P31785, SEQ ID NO: 7). The Type 2 receptor is a heterodimer consisting of IL4 R-alpha and IL13R-alpha1 (IL13RA1, CD213a1, UniProt P78552, SEQ ID NO: 8). IL13 (SEQ ID NO: 101) but not IL4 binds the Type 2 receptor by binding the IL13RA protein. In addition, IL13 binds IL13RA2 (SEQ ID NO: 102).
A “consensus amino acid residue” is the amino acid found most frequently at a certain position in a sequence identified by structural and/or sequence aligning of multiple repeat units. If two or more, e.g., three, four or five, amino acid residues are found with a similar probability in said two or more repeat units, the consensus amino acid may be one of the most frequently found amino acids or a combination of said two or more amino acid residues.
As used herein, the term “affinity” of binding between two molecules refers to a biophysical measurement of strength of interaction. The term “Kdis” or “KD” or “Kd” as used herein, is intended to refer to the dissociation rate of a particular composition-target interaction. The “KD,” is the ratio of the rate of dissociation (k2), also called the “off-rate (koff)” or “kd”, to the rate of association (k1) or “on-rate (kon)” or “ka.” Thus, KD equals k2/k1 or koff/kon or kd/ka and is expressed as a molar concentration (M). It follows that the smaller KD, the stronger the binding. Thus, a KD of 10−6M (or 1 μM) indicates weak binding compared to 10−9M (or 1 nM). The KD can be determined by surface plasmon resonance or the Kinexa method, as practiced by those of skill in the art. The measured affinity of a particular protein-protein interaction can vary if measured under different conditions (e.g., salt concentration, pH). Thus, measurements of affinity (e.g., KD, kon, koff) are preferably made with standardized solutions of protein, and a standardized buffer.
The repeat proteins of the invention, selected for their biological activity resulting from interactions with other proteins or peptides, can be further modified to enhance or impart additional biophysical or biological properties to the molecules such as a polypeptide tag, a radioisotope, a chelator, and a multimerizing domain, which may be of a proteinaceous or a nonproteinaceous nature. For example, the ability to persist in the body can be enhanced by the addition of certain physiologically compatible polymers or the fusion of an immunoglobulin constant domain sequence to the protein. Examples of non-proteinaceous polymer molecules are hydroxyethyl starch (HES), polyethylene glycol (PEG), polypropylene glycol, or polyoxyalkylene. Modifications that enhance the ability of the protein to persist in the body through a decrease in clearance or increase in re-uptake are referred to as “half-life extending” modifications.
The term “polypeptide tag” refers to an amino acid sequence attached to a polypeptide/protein, wherein said amino acid sequence is useful for the purification, detection, or targeting of said polypeptide/protein, or wherein said amino acid sequence improves the physicochemical behavior of the polypeptide/protein, or wherein said amino acid sequence possesses an effector function. The individual polypeptide tags, moieties and/or domains of a binding protein may be connected to each other directly or via polypeptide linkers. These polypeptide tags are all well known in the art and are fully available to the person skilled in the art. Examples of polypeptide tags are small polypeptide sequences, for example, His, myc, FLAG, or Strep-tags or moieties, such as enzymes (for example enzymes like alkaline phosphatase), which allow the detection of said polypeptide/protein, or moieties which can be used for targeting (such as immunoglobulins or fragments thereof) and/or as effector molecules.
Examples of multimerization moieties are immunoglobulin heavy chain constant regions which pair to provide functional immunoglobulin Fc domains, and leucine zippers or polypeptides comprising a free thiol which forms an intermolecular disulfide bond between two such polypeptides.
The term “polypeptide linker” refers to an amino acid sequence, which is able to link, for example, two protein domains, a polypeptide tag and a protein domain, a protein domain and a non-polypeptide moiety, such as polyethylene glycol or two sequence tags. Such additional domains, tags, non-polypeptide moieties and linkers are known to the person skilled in the relevant art. A polypeptide linker or any intervening sequence between the repeat modules may be any sequence which does not interfere with the topology or the fold of the module or the ability of the modules to stack. Particular examples of such linkers are flexible glycine-serine-linkers of variable lengths; preferably, said linkers have a length between 2 and 16 amino acids, and Proline-Threonine linkers.
New IL4 and IL13 binding proteins were identified using libraries of repeat proteins comprising a consensus 33 amino acid ankyrin repeat module containing diversified potential interaction residues (any amino acid except cysteine, glycine or proline). As described herein, the amino acids at randomized positions in stacked repeat modules form an interaction surface that can bind with high affinity to a variety of targets (
In a specific embodiment, the invention relates to a recombinant IL4 binding protein comprising a binding domain with specificity for IL4 selected from a library of repeat proteins comprising one or more repeat modules with the AR sequence motif
wherein X1, X3, X4, X6, X14, and X15 represent, independently of each other, an amino acid residue selected from the group consisting of A, D, E, F, H, I, K, L, M, N, Q, R, S, T, V, W and Y. X27 represents A, H, N, or Y;
an N-terminal capping module of the amino acid sequence:
and a C-terminal capping module has an amino acid sequence:
The term “AR” means an ankyrin repeat module and “AR1” means the first tandem AR of an ankyrin repeat domain, the term “AR2” means the second AR of an ankyrin repeat domain, the term “AR3” means the third AR of an ankyrin repeat domain, and the term “AR4” means the fourth AR of an ankyrin repeat domain. When arranged in tandem, the AR1 module is N-terminus of the AR2 module; the AR2 module is N-terminus of the AR3 module and, as applicable, the AR3 module is N-terminus of the AR4 module such that an AR arrangement is AR1-AR2-AR3-AR4. ARs do not include N-Cap or C-Cap sequences and, preferably, each AR has an N-Cap and C-Cap module. It will be appreciated that SEQ ID NO:2 is an example of an N-Cap sequence and SEQ ID NO:3 is an example of an C-Cap sequence and that these sequences may be modified as needed.
In specific embodiment, the invention relates to a recombinant IL13 binding protein comprising a binding domain with specificity for IL13 selected from a library of repeat proteins comprising one or more repeat modules with the AR sequence motif
wherein X1, X2, X3, X4, X5, and X6 represent, independently of each other, an amino acid residue selected from the group consisting of A, D, E, F, H, I, K, L, M, N, Q, R, S, T, V, W and Y. X7 represents A, H, N, and Y;
an N-terminal capping module of the amino acid sequence (wherein bracketed sequences mean alternate amino acids for that position):
a C-terminal capping module has an amino acid sequence:
In addition to substitutions of the residues at the positions diversified in the creation of libraries based on the formula N-Cap-[AR]n—C-Cap; generic binding protein mutations are encompassed by the identified binding protein structures. Generic mutations can be applied to any binding protein of the invention, in that these mutations occur within positions of the sequence that are common to all binding proteins of the above referenced library of binding domains. Common generic changes to specified residues of a binding domain of the invention are as summarized below.
Position 1 of the N-Cap is mutated from Asp to Gly or Ala to aid in the processing of the N-terminal methionine residue for expression in E. coli (Hirel et. al. PNAS 86:8247-8251 1989). Position 3 of the N-Cap is mutated from Gly to Asp, as this mutation has been found to stabilize the repeat protein consensus sequence as described in WO2010/060748. As the AR sequence motif (SEQ ID NO: 1) position 28 of the framework is Gly, there is the possibility of isolating AR proteins consisting of the sequence Asn27-Gly28. The Asn-Gly di-peptide is prone to deamidation reactions (Geiger and Clarke J. Biol. Chem. 252:785-794, 1987) and therefore position 27 of isolated Asn-Gly sequences can be mutated to His, Tyr or Ala to avoid potential deamidation. In some cases, the residue at position 27 is changed to Ala to reduce the potential immunogenicity of the region of the protein. Finally, target binding AR proteins selected by ribosome display end with the amino acid sequence Leu-Asn in the C-cap. This sequence is appended onto the AR proteins in order to accommodate a restriction site for sub-cloning into expression vectors for screening. The preferred amino acid sequence of these positions is Ala-Ala.
The invention relates to a binding protein comprising a binding domain, wherein said binding domain inhibits IL13 binding to IL13Ralpha1 or IL13Ralpha2 or IL4 binding to IL4RA and wherein said binding protein and/or binding domain has a midpoint denaturation temperature (Tm) above 40° C. upon thermal unfolding and forms less than 5% (w/w) insoluble aggregates at concentrations up to 10 g/L when incubated at 37° C. for 1 day in phosphate buffered saline (PBS). In a specific embodiment, the IL13 binding protein is comprised of two or three repeat modules represented by SEQ ID NO: 1 proceeded by an N-terminal capping module such as SEQ ID NO: 2 or 174, and followed by a C-terminal capping module such as SEQ ID NO: 3 or 175.
The invention relates to a binding protein comprising a binding domain, wherein said binding domain inhibits IL4 binding to IL4RA. Preferably, the KD for the interaction of the binding domain to IL4 is below 10−7M, below 10−8 M, below 10−9M, or, in certain embodiments below 10−10M. Methods to determine dissociation constants of protein-protein interactions, such as surface plasmon resonance (SPR) based technologies, are well known to the person skilled in the art.
The invention relates also to a binding protein comprising a binding domain, wherein said binding domain inhibits IL13 binding to IL13Ralpha1 and/or IL13Ralpha2. Preferably, the KD for the interaction of the binding domain to IL13 is below 10−7M, below 10−8M, below 10−9M, or, in certain embodiments below 10−10M. Methods to determine dissociation constants of protein-protein interactions, such as surface plasmon resonance (SPR) based technologies, are well known to the person skilled in the art.
Preferably, the binding protein and/or binding domain has a midpoint denaturation temperature (Tm) above 45° C., more preferably above 50° C., more preferably above 55° C., and most preferably above 60° C. upon thermal unfolding. A binding protein or a binding domain of the invention possesses a defined secondary and tertiary structure under physiological conditions. Thermal unfolding of such a polypeptide results in a loss of its tertiary and secondary structure, which can be followed, for example, by circular dichroism (CD) measurements. The midpoint denaturation temperature of a binding protein or binding domain upon thermal unfolding corresponds to the temperature at the midpoint of the cooperative transition in physiological buffer upon heat denaturation of said protein or domain by slowly increasing the temperature from 10° C. to about 100° C. The determination of a midpoint denaturation temperature upon thermal unfolding is well known to the person skilled in the art. This midpoint denaturation temperature of a binding protein or binding domain upon thermal unfolding is indicative of the thermal stability of said polypeptide.
Also preferred is a binding protein and/or binding domain forming less than 5% (w/w) insoluble aggregates at concentrations up to 20 g/l, preferably up 40 g/L, more preferably up to 60 g/L, even more preferably up to 80 g/L, and most preferably up to 100 g/L when incubated for over 5 days, preferably over 10 days, more preferably over 20 days, more preferably over 40 days, and most preferably over 100 days at 37° C. in aqueous solution. The formation of insoluble aggregates can be detected by the appearance of visual precipitations, gel filtration or dynamic light scattering, which strongly increases upon formation of insoluble aggregates. Insoluble aggregates can be removed from a protein sample by centrifugation at 10,000×g for 10 minutes. Preferably, a binding protein and/or binding domain forms less than 2%, 1%, 0.5%, 0.2%, 0.1%, or 0.05% (w/w) insoluble aggregates under the mentioned incubation conditions at 37° C. in PBS. Percentages of insoluble aggregates can be determined by separation of the insoluble aggregates from soluble protein, followed by determination of the protein amounts in the soluble and insoluble fraction by standard quantification methods.
Bioactivity
An EC50 value is the concentration of a substance, such as a binding protein or binding domain, which is required to produce for 50% of the complete or predetermined maximum effect under a specific set of conditions. When the effect is blocking or inhibiting an activity, the value is termed an inhibitory concentration producing 50% reduction in the effect (IC50). An IC50 value may be applied to inhibition in vitro of an experimental determined parameter, such as the release of a detectable amount of a pathologic marker, or biomarker, from a cell, tissue, organ or in the body of a subject or animal. Such measurements may be direct measures of the activity of the protein composition or may be surrogates or downstream markers of the biological activity to be modified.
IL4 shares several biological activities with IL13. For example, either IL4 or IL13 can cause IgE isotype switching in B cells (Tomkinson et al. 2001 J. Immunol. 166:5792-5800). Additionally, increased levels of cell surface CD23 and serum CD23 (sCD23) have been reported in asthmatic patients (Sanchez-Guererro et al. (1994) Allergy 49:587-92; DiLorenzo et al. (1999) Allergy Asthma Proc. 20.119-25). In addition, either IL4 or IL13 can upregulate the expression of MHC class II and the low-affinity IgE receptor (CD23) on B cells and monocytes, which results in enhanced antigen presentation and regulated macrophage function (Tomkinson et al., supra). Importantly, either IL4 or IL13 can increase the expression of VCAM-1 on endothelial cells, which facilitates preferential recruitment of eosinophils (and T cells) to the airway tissues (Tomkinson et al., supra). Either IL4 or IL13 can also increase airway mucus secretion, which can exacerbate airway responsiveness (Tomkinson et al., supra). By acting to block signaling pathways which are different from those of IL13, IL4 inhibitors/antagonists can be used to inhibit differentiation of naïve T-cells to Th2 cells.
The present invention further relates to methods for using a binding protein which has both IL4 and IL13 neutralizing activity as described to inhibit an IL4 and IL13 mediated biological activity including but not limited to: IgE production; CD23 upregulation on B cells or monocytes; upregulation of VCAM-1 on endothelial cells, eosinophil recruitment, TGFbeta induction, increased mucus secretion; fibrosis caused by fibroblast proliferation, collagen synthesis, and extracellular-matrix remodeling (Wynn T A et al. Nat Rev Immunol. 2004; 4: 583-94) or by stimulation of TGFbeta; and stimulation of 15-lipoxygenase activity with relaese of leukotrienes (e.g., LTA4, LTB4, LTC4, LTD4, LTE4, and/or LTF4). Therefore, any of IgE production, LTA4 and LTB4 release from blood monocytes, eosinophil recruitment, TGFbeta release, enhanced collagen synthesis, and extracellular-matrix remodeling may be used as measurement of the bioactivity of the effects of the IL4 or IL13 binding protein described herein.
IL13 bioassays also include the proliferation of cancerous or precancerous cell types such as TF-1 erythroleukemic cells. IL13 neutralization can be measured specifically as the ability of the IL13 binding protein to reduce IL13 binding to IL13R-alpha1 or IL13R-alpha2.
An IL13 binding composition of the invention can inhibit IL13 binding in a way that the apparent dissociation constant (Kd) between IL13 and IL13Ralpha2 or IL13Ralpha2 or an IL4 binding composition of the invention can inhibit IL4 binding in a way that the apparent dissociation constant (Kd) between IL4 and IL4RA is increased more than 102-fold, preferably more than 103-fold, more preferably more than 104-fold, more preferably more than 105-fold, and most preferably more than 106-fold. Preferred for IL13-binding is a binding protein and/or binding domain that inhibits IL13 or the human IL13 R130Q protein variant (IL13 R130Q—Vladich et al. “IL13 R130Q, a common variant associated with allergy and asthma, enhances effector mechanisms essential for human allergic inflammation” J Clin Invest. 2005; 115(3):747-754) binding to IL13Ralpha2 under specified in vitro conditions with an IC50 value below 100 nM, preferably below 10 nM, and more preferably below 1.0 nM.
IL4 neutralization can be measured specifically as the ability of the IL4 binding protein to reduce IL4 binding to IL4 RA. The IL4 binding proteins of the invention are characterized by the ability to inhibit IL4 dependent phosphorylation of STAT6 in a cell expressing a Type 2 IL4 receptor complex, such as a recombinant HEK cell line expressing a STAT6-bla reporter. The IL4 binding proteins are further characterized as having the additional property of being able to block or reduce signaling in a cell having the Type 1 IL4 receptor complex, such as demonstrated by inhibiting naive T-cell differentiation to the Th2 phenotype. The IL4 binding protein may block or reduce stimulation of IL-4 dependent TARC production from cells, such as A549 cells in the presence of 67 pM IL4. The IL4 binding protein of the invention binds to human and to Macaque spp. monkey IL4 homolog protein.
When an IL4 binding protein of the invention is coupled to an IL13 binding protein, the composition can inhibit IL13 binding in a way that the apparent dissociation constant (Kd) between IL13 and IL13Ralpha1 or IL13Ralpha2 is increased more than 102-fold, preferably more than 103-fold, more preferably more than 104-fold, more preferably more than 105-fold, and most preferably more than 106-fold. Preferred is a binding protein and/or binding domain that inhibits IL13 or the human IL13 R130Q protein variant (IL13 R130Q, Vladich et al. J Clin Invest. 2005; 115(3):747-754) binding to IL13Ralpha2 under specified in vitro conditions with an IC50 value below 100 nM, preferably below 10 nM, and more preferably below 1.0 nM.
One embodiment of the invention is a binding protein comprising a repeat module capable of blocking human IL4 or IL4 and IL13 activation of STAT6 phosphorylation in HEK-Blue STAT-6 cells which display the IL13Ralpha1 and IL4 RA proteins and, which when activated by IL4 or IL13, induces secretion of a reporter protein which is an active enzyme alkaline phosphatase capable of transforming substrate to a chromophor. The binding protein of the invention inhibits IL4 or IL4 and IL13 activation of STAT6 with an IC50 of 1 nM or less, and preferably, 100 pM or less, and more preferably 10 pM or less in an in vitro assay. In addition, the binding protein of the invention inhibits cyno IL4 or IL13 from binding to the same cells with an IC50 which is 5 nM or less, and preferably 1 nM or less and, in addition, where the ratio between the IC50 for human IL4 or IL13 and the cynomolgous homologue IL4 or IL13 IC50 inhibition of STAT6 in engineered HEK-blue cells is 10 or less in an in vitro assay. Representative assays are described herein an known to those in the art.
Whereas, thymus and activation-regulation chemokine (TARC) is upregulated by IL13 (Imai et al. (1999) Int. Immunol. 11:81-88), induces the migration of TH2 cells (Hijnen et al. (2004) J. All. Clin. Immun. 113(2):334-40) and is upregulated in the airways of asthmatic patients (Leung et al. (2004) J. All. Clin. Immun. 114(1): 199-202); an embodiment of the binding protein and/or binding domain of the invention will inhibit TARC production by A549 cells with an IC50 value below 500 pM, preferably below 100 pM, and more preferably below 50 pM in the presence of 67 pM IL4.
Compositions
The IL4-binding AR compositions of the invention conform to the formula of a binding protein (N-Cap-[AR]n—C-Cap (I)) having two or three repeat modules which have affinity for binding to IL13 measured as a KD of 10−6 M or less, a KD of 10−7 M or less, a KD of 10−8 M or less, or a KD of 10−9 M or less, which binding protein molecules are comprised of a repeat module of SEQ ID NO: 1. In one embodiment of the IL4-binding protein, the AR domain comprises a repeat module with the sequence selected from any of SEQ ID NOS: 31-81.
In a particular embodiment of the invention, the IL4-binding protein, the AR1 sequence is selected from the group consisting of SEQ ID NOS: 31-46; followed by a second designed ankyrin repeat domain (AR2) selected from the group consisting of SEQ ID NOS: 47-61; and, optionally, where the second designed ankyrin repeat unit is followed by a third designed ankyrin repeat (AR3) unit selected from the group consisting of SEQ ID NOS: 62-78; and, optionally, the AR3 repeat unit is followed by an AR4 unit selected from the group consisting of SEQ ID NO: 79-81.
In a particular embodiment, the IL4 binding protein comprises an ankyrin repeat module with the ankyrin repeat sequence of SEQ ID NO: 53, wherein said repeat module is preceded by a repeat module with the ankyrin repeat sequence motif of SEQ ID NO: 36 and/or followed by a repeat module with the ankyrin repeat sequence motif of SEQ ID NO: 68.
In a particular embodiment, the IL4 binding protein comprises an ankyrin repeat module with the ankyrin repeat sequence of SEQ ID NO: 56, wherein said repeat module is preceded by a repeat module with the ankyrin repeat sequence motif of SEQ ID NO: 39 and/or followed by a repeat module with the ankyrin repeat sequence motif of SEQ ID NO: 71.
In a particular embodiment, the IL4 binding protein comprises an AR unit with the sequence of SEQ ID NO: 59, wherein said repeat module is preceded by a repeat module with the AR sequence motif of SEQ ID NO: 43 and/or followed by a repeat module with the AR sequence motif of SEQ ID NO: 74.
In further embodiments exemplified herein, the AR units tandem arrangement is as specified in Table 3 by the designated SEQ ID NO: corresponding to the AR sequence motif at the specified position in the binding protein.
In one embodiment, the invention is an IL4 binding protein, wherein one AR unit selected from SEQ ID NOS: 31-81 is preceded by an N-Cap comprising SEQ ID NO: 2 and variants thereof. The variants comprise SEQ ID NO: 1 and molecules having 75% or greater identity to any of the molecules of SEQ ID NOS: 31-81 that bind to IL4 protein. In another embodiment, the invention is an IL4 binding protein, wherein one AR unit selected from SEQ ID NOS: 31-81 is followed by a C-cap comprising SEQ ID NO: 3 and variants thereof.
The IL4 binding protein having a binding domain with binding specificity for IL4 comprising the AR unit sequence selected from SEQ ID NOS: 31-81, may have its sequence modified for the purpose of: improving expression in a host cell, reducing the potential for one or more residues to undergo oxidation, reducing the potential for residues to undergo chemical deamidation, reducing the potential for a host to which the binding protein is administered to mount an immunological response, and/or where one or more residues is added or modified for the purpose of joining the IL13 binding protein with another protein or moiety. The binding protein will retain the binding specificity, affinity, and biophysical characteristics of solubility in aqueous solutions and lack of tendency to self-aggregate, and have a melting temperature greater than 45° C.
The invention more specifically encompasses an IL4 binding protein derived from a consensus sequence (motif) or observed frequency of identity of a particular amino acid at a diversified position obtained from a multi-sequence alignment of repeat units. For example, the IL4 binding protein may comprise ankyrin repeat modules AR1, AR2, and AR3 arranged in tandem having sequence motif of SEQ ID NO: 1, and wherein the AR1 module has an amino acid according to the formula (wherein bracketed sequences mean alternate amino acids for that position):
In a preferred embodiment, the binding domains of the IL4 binding proteins include an N-capping module and a C-capping module as described and exemplified herein.
The IL13-binding AR compositions of the invention conform to the formula of a binding protein (N-Cap-[AR]n—C-Cap (I)) having two or three repeat modules which have affinity for binding to IL13 measured as a KD of 10−6 M or less, a KD of 10−7 M or less, a KD of 10−8 M or less, or a KD of 10−9 M or less, which binding protein molecules are comprised of a repeat module of SEQ ID NO: 1. In one embodiment of the IL4-binding protein, the AR domain comprises a repeat module with the sequence selected from any of SEQ ID NOS: 108-155.
In a particular embodiment of the invention, the IL13-binding protein, the AR1 repeat sequence is selected from the group consisting of SEQ ID NOS: 108-125; followed by a second designed ankyrin repeat domain (AR2) selected from the group consisting of SEQ ID NOS: 109-143; and, optionally, where the second designed ankyrin repeat unit is, optionally, followed by a third designed ankyrin repeat domain (AR3) selected from the group consisting of SEQ ID NOS: 144-155.
The invention more specifically encompasses an IL13 binding protein derived from a consensus sequence (motif) or observed frequency of identity of a particular amino acid at a diversified position obtained from a multi-sequence alignment of repeat units. For example, the IL13 binding protein may comprise ankyrin repeat modules AR1, AR2, and AR3 arranged in tandem having sequence motif of SEQ ID NO: 1, and wherein the AR1 module has an amino acid sequence according to the formula:
In one embodiment of the IL13-binding protein, the AR domain comprises a repeat module with the sequence selected from any of SEQ ID NOS: 108-155. In another embodiment, a binding protein with an AR domain, N-Cap and C-cap modules, may be constructed using the formulas provided herein for the tandem repeat modules such as N-Cap-[AR1-C:AR2-C:AR3-C]-C-cap where the repeat modules are specified by SEQ ID NO: 156, 158 and 160; or N-Cap-[AR1-F:AR2-F:AR3-F]-C-cap where the repeat modules are specified by SEQ ID NO: 157, 159, and 161; or N-Cap-[AR1-O:AR2-O:AR3-O]-C-cap where the repeat modules are specified by SEQ ID NO: 168, 169, and 170; and the N-cap and C-cap are specified by SEQ ID NO: 2 or 171 and SEQ ID NO: 3 and 172, respectively, or modification as described herein or as required for further chemical linkage, biological processing, and the like.
The IL13 binding protein comprising at least one repeat domain with binding specificity for IL13 comprising the repeat unit sequence selected from SEQ ID NOS: 108-155, may have its sequence modified for the purpose of: improving expression in a host cell, reducing the potential for one or more residues to undergo oxidation, reducing the potential for residues to undergo chemical deamidation, reducing the potential for a host to which the binding protein is administered to mount an immunological response, and/or where one or more residues is added or modified for the purpose of joining the IL13 binding protein with another protein or moiety. The binding protein will retain the binding specificity, affinity, and biophysical characteristics of solubility in aqueous solutions and lack of tendency to self-aggregate, and have a melting temperature greater than 45° C.
In one embodiment, the invention is an IL13 binding protein, wherein one ankyrin repeat module selected from SEQ ID NOS: 108-155 is preceded by an N-Cap comprising SEQ ID NO: 2 and variants thereof. The variants comprise SEQ ID NO:1 and molecules having 75% or greater identity to any of the molecules of SEQ ID NOS: 162-167 that bind to IL13 protein and/or IL13 R130Q. In another embodiment, the invention is an IL13 binding protein, wherein one ankyrin repeat domain selected from SEQ ID NOS: 162-167 is followed by a C-cap comprising SEQ ID NO: 3 and variants thereof. In further embodiments exemplified herein, the AR units tandem arrangement is as specified in Table 4 by the designated SEQ ID NO: corresponding to the AR sequence motif at the specified position in the binding protein.
In one embodiment, the invention is an IL13 binding protein, wherein one AR unit selected from SEQ ID NOS: 108-155 is preceded by an N-Cap comprising SEQ ID NO: 2 and variants thereof. The variants comprise SEQ ID NO: 1 and molecules having 75% or greater identity to any of the molecules of SEQ ID NOS: 108-155 that bind to IL13 protein. In another embodiment, the invention is an IL13 binding protein, wherein one AR unit selected from SEQ ID NOS: 108-155 is followed by a C-cap comprising SEQ ID NO: 3 and variants thereof.
A binding protein that competes with IL13Ralpha2 for binding to IL13 with a selected repeat domain can be identified by methods well known to the person skilled in the art, such as a competition Enzyme-Linked ImmunoSorbent Assay (ELISA). Further, a modified binding protein having one or more modified repeat unit sequences may be tested for activity using a competition binding to IL13 with a binding protein known to compete with IL13Ralpha2 for binding to IL13.
Functional Properties
An IL4 binding protein that competes with IL4RA for binding to IL4 or an IL13 binding protein that competes with IL13Ralpha1 and IL13Ralpha2 for binding to IL13 with a selected repeat domain can be identified by methods well known to the person skilled in the art, such as a competition Enzyme-Linked ImmunoSorbent Assay (ELISA). Further, where a modified IL4 or IL13 neutralizing binding protein having one or more modified repeat unit sequences is desired to be produced, the activity of the modified binding protein may be tested for activity using a competition binding to of the modified binding protein with the unmodified protein. A modified IL4 binding protein may be tested in competition with a known IL4 binding protein for binding to IL4 and a modified IL13 binding protein may be tested in competition with an IL13 binding protein known to compete with IL13Ralpha1 and IL13Ralpha2 for binding to IL13.
In one embodiment of a modified binding protein, one or more of the amino acid residues of the repeat modules of said repeat domain are exchanged by an amino acid residue found at the corresponding position on alignment of a repeat unit. In one aspect, up to 30% of the amino acid residues are exchanged, more frequently, up to 20%, and even more frequently, up to 10% of the amino acid residues are exchanged. Most preferably, the source of the exchanged residue is a repeat unit which is a naturally occurring repeat unit. In still another particular embodiment, the amino acid residues are exchanged with amino acids which are not found in the corresponding positions of repeat units.
In further embodiments, any of the IL4 and/or IL13 binding proteins or domains described herein may be covalently bound to one or more additional moieties, including, for example, a moiety that improves persistence in the circulation or decreases elimination from the body (i.e., improves pharmacokinetics), a labeling moiety (e.g., a fluorescent label, such as fluorescein, or a radioactive tracer), a moiety that facilitates protein purification (e.g., a small peptide tag, such as a His- or strep-tag), a moiety that provides effector functions for improved therapeutic efficacy (e.g., the Fc part of an antibody to provide antibody-dependent cell-mediated cytotoxicity), a toxic protein moiety, such as Pseudomonas aeruginosa exotoxin A (ETA) or a small molecular toxic agent such as a maytansinoid, calicheamicin, or platinum containing DNA alkylating agents. Improved pharmacokinetics may be assessed according to the perceived therapeutic need. Often it is desirable to increase bioavailability and/or increase the time between doses, possibly by increasing the time that a protein remains available in the serum after dosing. In some instances, it is desirable to improve the continuity of the serum concentration of the protein over time (e.g., decrease the difference in serum concentration of the protein shortly after administration and shortly before the next administration). Moieties that slow clearance of a protein from the blood include hydroxyethyl starch (HES), polyethylene glycol (PEG), sugars (e.g., sialic acid), well-tolerated protein moieties (e.g., Fc fragment or serum albumin), and binding domains or peptides with specificity and affinity for abundant serum proteins, such as those capable of binding to serum albumin.
Nucleic Acids and Uses
In a further embodiment, the invention relates to nucleic acid molecules encoding the particular IL4 and/or IL13 binding proteins and, further, a vector comprising the nucleic acid molecule. In general, a bacterial expression vector will contain (1) regulatory elements, usually in the form of viral promoter or enhancer sequences and characterized by a broad host and tissue range; (2) a sequence, facilitating the insertion of a DNA fragment within the vector; and (3) the sequences encoding the final protein. The vector will likely also contain (4) a selectable marker gene(s) (e.g., the beta-lactamase gene), often conferring resistance to an antibiotic (such as ampicillin), allowing selection of initial positive transformants; and (5) sequences facilitating the replication of the vector in bacterial and mammalian host cells, or sequences promoting stable insertion into the genome of the host. A plasmid origin of replication are included for propagation of the expression construct in bacteria such as E. coli and for transient expression in Cos cells, the SV40 origin of replication is included in the expression plasmid. In addition, a suitable mammalian cell line may be used having the properties addressed above.
Therefore, the invention contemplates host cells used in the recombinant expression of the IL4 and IL13 binding protein repeat domains and proteins and more complex constructs comprising the IL4 and IL13 binding repeat proteins, which host cells will comprise the nucleic acids encoding such proteins. The IL4 and IL13 binding proteins may be purified from cultures in which such host cells are maintained as batch or continuous cultures by methods known in the art. The isolated proteins may be expressed with appended moieties, such as tags, that facilitate purification and which can be subsequently removed prior to final formulation and packaging of the protein for its intended use.
A pharmaceutical composition of the invention comprises one or more of the above mentioned binding proteins, in particular, binding proteins comprising repeat domains, or nucleic acid molecules encoding the particular binding proteins and, optionally, a pharmaceutically acceptable carrier and/or diluent. Pharmaceutically acceptable carriers and/or diluents are known to the person skilled in the art and are explained in more detail below. Even further, the invention comprises a diagnostic composition comprising one or more of the above mentioned binding proteins, in particular, binding proteins comprising repeat domains. Where delivery of a nucleic acid encoding the IL4 and IL13 binding protein is performed, the pharmaceutical preparation of the therapy vector can include the vector in an acceptable diluent, or can comprise a slow release matrix in which the vector is imbedded. Alternatively, where the complete vector can be produced intact from recombinant cells, e.g., retroviral vectors, the pharmaceutical preparation can include one or more cells which produce the nucleic acid delivery system.
A pharmaceutical composition of the invention is a stable formulation comprising the IL4 and IL13 binding protein, which may be an aqueous phosphate buffered saline or mixed salt solution or, alternatively, preserved solutions and formulations, multi-use preserved formulations suitable for pharmaceutical or veterinary use in a pharmaceutically acceptable formulation. Suitable vehicles and their formulation, inclusive of other proteins, e.g., human serum albumin, are described, for example, in e.g. Remington: The Science and Practice of Pharmacy, 21st Edition, Troy, D. B. ed., Lipincott Williams and Wilkins, Philadelphia, Pa. 2006, Part 5, Pharmaceutical Manufacturing pp 691-1092, See especially pp. 958-989. The formulations to be used for in vivo administration may be aseptic or sterile. This is readily accomplished by filtration through sterile filtration membranes but other methods may be applied, such as heat, gas or chemical sterilization, or by the use of ionizing radiation to some or all of the components of the formulation.
The pharmaceutical composition may be administered by any suitable method within the knowledge of the skilled practitioner, wherein the administration may be performed by another or self-administered. The route of administration may be selected from a variety of delivery methods including but not limited to: intravenous (I.V.); intramusclular (I.M.); subcutaneous (S.C.); transdermal; pulmonary; transmucosal (oral, intranasal, intravaginal, rectal); using a formulation in a tablet, capsule, solution, powder, gel, particle; and contained in a syringe, an implanted device, osmotic pump, cartridge, micropump; or other means appreciated by the skilled artisan, as well-known in the art.
For example, site specific administration may be to body compartment or cavity such as intrarticular, intrabronchial, intraabdominal, intracapsular, intracartilaginous, intracavitary, intracelial, intracelebellar, intracerebroventricular, intracolic, intracervical, intragastric, intrahepatic, intracardial, intraosteal, intrapelvic, intrapericardiac, intraperitoneal, intrapleural, intraprostatic, intrapulmonary, intrarectal, intrarenal, intraretinal, intraspinal, intrasynovial, intrathoracic, intrauterine, intravascular, intravesical, intralesional, vaginal, rectal, buccal, sublingual, intranasal, or transdermal means.
The IL4 and IL13 binding protein can be administered directly to the respiratory tract by a nebulizer, such as jet nebulizer or an ultrasonic nebulizer. Typically, in a jet nebulizer, a compressed air source is used to create a high-velocity air jet through an orifice. As the gas expands beyond the nozzle, a low-pressure region is created, which draws a solution of protein through a capillary tube connected to a liquid reservoir. The liquid stream from the capillary tube is sheared into unstable filaments and droplets as it exits the tube, creating the aerosol. A range of configurations, flow rates, and baffle types can be employed to achieve the desired performance characteristics from a given jet nebulizer. In an ultrasonic nebulizer, high-frequency electrical energy is used to create vibrational, mechanical energy, typically employing a piezoelectric transducer. This energy is transmitted to the formulation of protein either directly or through a coupling fluid, creating an aerosol including the protein. Advantageously, particles of protein delivered by a nebulizer have a particle size less than about 10 μm, preferably in the range of about 1 μm to about 5 μm, and most preferably about 2 μm to about 3 μm.
Indications
The invention further provides novel methods of treatment of IL4 and IL13 mediated diseases and conditions, in particular, respiratory conditions, such as asthma and pulmonary fibrosis, cardiovascular conditions, cancer, dermatological, and fibrotic conditions. The present invention provides high affinity IL4/IL13 bispecific binding proteins, and nucleic acids encoding them, capable of blocking the biological activity of IL4, in vitro, in vivo, or in situ including, but not limited to, inhibiting wild-type or natural variants of human IL4 binding to IL-4RA or fragments thereof, inhibiting IL4 RA complexes on cells from signaling in the presence of IL4, and preventing or suppressing IL4-dependent differentation of naïve T-cells to Th2 cells.
Binding proteins capable of binding and neutralizing IL13 have one or more properties selected from: inhibiting binding of IL13 to human IL13 receptor alpha 1 (IL13Ralpha1) (UniProt. P78552) or fragments thereof, inhibiting human IL13 or natural variants of human IL13 binding to the human IL13 receptor alpha 2 (IL13Ralpha2) (UniProt. Q14627) or fragments thereof, preventing or suppressing human IL13-dependent proliferation of human tumor cells, inhibiting human IL13-dependent IgE production, reducing eosinophilic infiltration of tissues, and which protein has a specific binding site on human IL13.
In one aspect, a method of treating a human patient afflicted with a disease or disorder selected from the group consisting of a form of asthma which can be named allergic asthma, severe asthma, difficult asthma, brittle asthma, nocturnal asthma, premenstrual asthma, steroid resistant asthma, steroid dependent asthma, aspirin induced asthma, adult-onset asthma, pediatric asthma, or exercise induced asthma; atopic disease such as atopic dermatitis; allergic rhinitis; Crohn's disease; COPD; fibrotic diseases or disorders such as idiopathic pulmonary fibrosis, progressive systemic sclerosis, hepatic fibrosis, radiation-induced fibrosis, chemotherapy-induced fibrosis; hepatic granulomas; schistosomiasis, leishmaniasis, diseases of cell cycle regulation such as Hodgkins disease; B cell chronic lymphocytic leukaemia; which method comprises administering a therapeutically effective amount of an IL4/IL13 binding protein.
Examples of IL4/IL13-associated disorders or conditions include, but are not limited to, disorders chosen from one or more of: IgE-related disorders, including but not limited to, atopic disorders, e.g., resulting from an increased sensitivity to IL4/IL13 (e.g., atopic dermatitis, urticaria, eczema, and allergic conditions such as allergic rhinitis and allergic enterogastritis); respiratory disorders, e.g., asthma (e.g., allergic and nonallergic asthma (e.g., asthma due to infection with, e.g., respiratory syncytial virus (RSV), e.g., in younger children)), chronic obstructive pulmonary disease (COPD), and other conditions involving airway inflammation, eosinophilia, fibrosis and excess mucus production, e.g., cystic fibrosis and pulmonary fibrosis, systemic sclerosis (SSc), and idiopathic pulmonary fibrosis (IPF) and sarcoidosis, desquamative interstitial pneumonia, acute interstitial pneumonia, respiratory bronchiolitis-associated interstitial lung disease, idiopathic bronchiolitis obliterans with organizing pneumonia; lymphocytic interstitial pneumonitis; Langerhans' cell granulomatosis; idiopathic pulmonary hemosiderosis; acute bronchitis; pulmonary alveolar proteinosis; bronchiectasis; atelectasis; cystic fibrosis; inflammatory and/or autoimmune disorders or conditions, gastrointestinal disorders or conditions (e.g., inflammatory bowel diseases (IBD) and eosinophilic esophagitis (EE), and eosinophilic-mediated gastrointestinal disease, ulcerative colitis and/or Crohn's disease), liver disorders or conditions (e.g., cirrhosis, hepatocellular carcinoma), and scleroderma; tumors or cancers (e.g., soft tissue or solid tumors), such as leukemia, glioblastoma, and lymphoma, e.g., Hodgkin's lymphoma; viral infections (e.g., from HTLV-I); fibrosis of other organs, e.g., fibrosis of the liver (e.g., fibrosis caused by a hepatitis B and/or C virus); and suppression of expression of protective type 1 immune responses, (e.g., during vaccination).
The method of treating a subject includes administering a high affinity IL4 and IL13 bispecific binding protein to the subject, in an amount effective to reduce one or more symptoms of the disorder or condition (e.g., in an amount effective to reduce one or more of: a respiratory symptom (e.g., bronchoconstriction), IgE levels, release or levels of histamine or leukotriene, or eotaxin levels in the subject). In the case of prophylactic use (e.g., to prevent, reduce or delay onset or recurrence of one or more symptoms of the disorder or condition), the subject may or may not have one or more symptoms of the disorder or condition.
In one embodiment, the high affinity IL4 and IL13 bispecific binding protein inhibits or reduces one or more symptoms associated with an early phase of the IL4 or IL13 associated disorder, e.g., an “early asthmatic response” or “EAR.” For example, the IL4 and IL13 bispecific binding protein reduces one or more symptoms associated with an EAR, at about 0.25 to 3 hours after an insult (e.g., allergen exposure) until about 3 hours after insult (e.g., allergen exposure). The IL4 and IL13 bispecific binding protein can decrease or prevent one or more symptoms of the EAR as compared to the level or degree of the symptom in the subject in the absence of the IL4 and IL13 bispecific binding protein. Alternatively, the IL4 and IL13 bispecific binding protein can prevent as large of an increase in the symptom, e.g., as compared to the level or degree of the symptom in the subject in the absence of the IL4 and IL13 bispecific binding protein) including, but not limited to, one or more of: a release of at least one allergic mediator such as a leukotriene and/or histamine, e.g., from airway mast or basophil cells; an increase in the levels of at least one allergic mediator, such as a leukotriene and/or histamine; bronchoconstriction; and/or airway edema.
In other embodiments, the IL4 and IL13 bispecific binding protein inhibits or reduces one or more symptoms associated with a late phase of an IL4 or IL13 associated disorder, e.g., a “late asthmatic response” or “LAR.” For example, the IL13 binding protein reduces one or more symptoms associated with an LAR, e.g., at about 3 hours and up to about 24 hours after an insult (e.g., allergen exposure). For example, the IL4 and IL13 bispecific binding protein can decrease or prevent one or more symptoms of the LAR (e.g., as compared to the level or degree of the symptom in the subject in the absence of the binding protein), e.g., one or more of: airway reactivity and/or an influx and/or activation of inflammatory cells, such as lymphocytes, eosinophils and/or macrophages, e.g., in the airways and/or bronchial mucosa. Alternatively, the IL4 and IL13 bispecific binding protein can prevent as large of an increase in the symptom, e.g., as compared to the level or degree of the symptom in the subject in the absence of the IL4 and IL13 bispecific binding protein.
The IL4 and IL13 bispecific binding protein can be administered prior to the onset or recurrence of one or more symptoms associated with the IL4/IL13-disorder or condition, but before a full manifestation of the symptoms associated with the disorder or condition. In certain embodiments, the IL4 and IL13 bispecific binding protein is administered to the subject prior to exposure to an agent that triggers or exacerbates an IL4/IL13-associated disorder or condition, e.g., an allergen, a pollutant, a toxic agent, an infection and/or stress. In some embodiments, the IL4 and IL13 bispecific binding protein is administered prior to, during, or shortly after exposure to the agent that triggers and/or exacerbates the IL13-associated disorder or condition. For example, the IL4 and IL13 bispecific binding protein can be administered 1, 5, 10, 25, or 24 hours; 2, 3, 4, 5, 10, 15, 20, or 30 days; or 4, 5, 6, 7 or 8 weeks, or more before or after exposure to the triggering or exacerbating agent. Typically, the IL4 and IL13 bispecific binding protein can be administered anywhere between 24 hours and 2 days before or after exposure to the triggering or exacerbating agent.
In another embodiment of the invention, an IL4 and IL13 bispecific binding protein inhibiting the activity of human IL4 or IL13 or naturally occurring variant, as described above, can be used in combination with a second binding protein or with an active that is a small molecule which can act additively or synergistically with the IL4 and IL13 bispecific binding protein or can act through a complementary mechanism to ameliorate one or more disease symptoms or sequelae. For example, an IL4 binding protein that is an IL4 antagonist could be administered with an IL13 binding protein. Since many disease pathologies are multi-factorial, efficacy may be improved by combining agents that inhibit multiple targets on one pathway or multiple targets on different pathways. One advantage of the IL4 and IL13 bispecific binding proteins of the invention is the ability to genetically link them together so that one binding protein inhibits one target and a second binding protein inhibits a different target or multiple targets. Alternatively, a specific cysteine residue could be introduced into a unique position on the binding protein that does not interfere with binding and used to directly couple a small molecule therapeutic. Coadministration of an IL4 and IL13 bispecific binding protein with a second therapeutic agent is also possible.
Examples of preferred additional therapeutic agents that can be coadministered and/or coformulated with an IL4 and IL13 bispecific binding protein include: inhaled steroids; beta-agonists, e.g., short-acting or long-acting beta-agonists; antagonists of leukotrienes or leukotriene receptors; combination drugs such as ADVAIR®; IgE inhibitors, e.g., anti-IgE antibodies (e.g., XOLAIR®); phosphodiesterase inhibitors (e.g., PDE4 inhibitors); xanthines; anticholinergic drugs; mast cell-stabilizing agents such as cromolyn; IL4 inhibitors (e.g., an IL4 inhibitor antibody, IL4 receptor fusion or an IL4 mutein); IL-5 inhibitors; eotaxin/CCR3 inhibitors; and antihistamines. Such combinations can be used to treat asthma and other respiratory disorders. Additional examples of therapeutic agents that can be co-administered and/or co-formulated with an IL4 and IL13 bispecific binding protein include one or more of: TNF antagonists (e.g., a soluble fragment of a TNF receptor, e.g., p55 or p75 human TNF receptor or derivatives thereof, e.g., 75 kd TNFR-IgG (75 kD TNF receptor-IgG fusion protein, ENBREL®)); TNF enzyme antagonists, e.g., TNFalpha converting enzyme (TACE) inhibitors; muscarinic receptor antagonists; TGFbeta antagonists; interferon gamma; perfenidone; chemotherapeutic agents, e.g., methotrexate, leflunomide, or a sirolimus (rapamycin) or an analog thereof, e.g., CCI-779; COX2 and cPLA2 inhibitors; NSAIDs; immunomodulators; and NFkB inhibitors, among others.
The IL4 and IL13 bispecific binding protein according to the invention may be obtained and/or further evolved by several methods, such as ribosomal display (WO 98/48008), display on the surface of bacteriophages (WO 90/02809, WO 07/006,665) (a different signal sequence that allows export of folded proteins may be required; Steiner, D. et al. JMB 2008 382(5) 1211-1227) or bacterial cells (WO 93/10214), display on plasmids (WO 93/08278) or by using covalent RNA-repeat protein hybrid constructs (WO 00/32823), or intracellular expression and selection or screening such as by protein complementation assay (WO 98/341120). Such methods are known to the person skilled in the art.
A library of ankyrin repeat proteins used for the selection, screening, and characterization of a binding protein according to the invention may be obtained according to protocols known to the person skilled in the art (WO 02/020565, Binz, H. K. et al., JMB, 332, 489-503, 2003, and Binz et al., 2004, loc. cit). The use of such a library for the selection of human IL4 and IL13 specific binding proteins is given in Example 1. In analogy, the ankyrin repeat sequence motifs as presented above can used to build libraries of ankyrin repeat proteins that may be used for the selection or screening of human IL4 and/or IL13 binding proteins. Furthermore, repeat domains of the present invention may be modularly assembled from repeat modules according the current inventions and appropriate capping modules (Forrer, P., et al., FEBS letters 539, 2-6, 2003) using standard recombinant DNA technologies (e.g. WO 02/020565, Binz et al., 2003, loc. cit. and Binz et al., 2004, loc. cit).
As the nucleic acids encoding the desired IL4 and/or IL13 binding repeat modules are identified from, for example, the libraries described herein comprising designed repeat modules coded in tandem repeats to form binding domains; they are isolated and used to form expression vectors for use as therapeutics or for construction of host cells for the purpose of preparing and purifying the IL4 and IL13 bispecific binding domains. The host cells may be bacterial, insect, plant, or mammalian and or may be selected from COS-1, COS-7, HEK293, BHK21, CHO, BSC-1, Hep G2, 653, SP2/0, 293, HeLa, myeloma, lymphoma, yeast, insect or plant cells; or may be any derivative, subline, immortalized or transformed cell related to the aforementioned cell types or cell lines.
The invention is not restricted to the particular embodiments described in the Examples. Other sources may be used and processed following the general outline described below.
All of the starting materials and reagents disclosed below are known to those skilled in the art, and are available commercially or can be prepared using well-known techniques.
Materials
Chemicals were purchased from Fluka (Switzerland). Oligonucleotides were from Microsynth (Switzerland). Unless stated otherwise, DNA polymerases, restriction enzymes and buffers were from New England Biolabs (USA) or Fermentas (Lithuania). The cloning and protein production strain was Escherichia coli XL1-blue (Stratagene, USA). The PBS used contained 137 mM NaCl, 10 mM phosphate, and 2.7 mM KCl at pH 7.4
Designed Ankyrin Repeat Protein Libraries
The N2C and N3C designed ankyrin repeat protein libraries are described (WO 02/20565; Binz et al. 2003, loc. cit.; Binz et al. 2004, Nat Biotechnol 22: 575-82, 2004; Binz, et al., J Mol Biol 332: 489-503, 2003). The digit in N2C (e.g., 2 ankyrin repeat modules) and N3C (e.g., 3 ankyrin repeat modules) describes the number of randomized ankyrin repeat modules present between the N-terminal and C-terminal capping modules. The nomenclature used to define the positions inside the repeat units and modules is based on Binz et al. 2004, loc. cit. with the modification that borders of the repeat modules and repeat units are shifted by one amino acid position. For example, position 1 of a repeat module of Binz et al. 2004 (loc. cit.) corresponds to position 2 of a repeat module of the current disclosure (SEQ ID NO: 1) and consequently position 33 of a repeat module or of the N-cap module of Binz et al. 2004, loc. cit. corresponds to position 1 of a following repeat module as presently described. All the DNA sequences were confirmed by sequencing.
The selection of IL4- and IL13-binding specific ankyrin repeat proteins was performed by ribosome display (Hanes and Plückthun, loc. cit.) using a recombinant human IL4 target protein (UniProt Accession No: PO5112, SEQ ID NO: 4) and IL13 protein.
Selection and Screening of Human IL4 Binding Proteins:
In total, nine ribosome display selection rounds on biotinylated human IL4 (Peprotech #200-04, mature protein produced in E. coli) were performed with the N2C and N3C AR protein libraries. The first four rounds were standard ribosome display selection rounds according to previously published protocols, using decreasing target concentration and increasing washing stringency to increase selection pressure from round 1 to round 4 (Binz, Amstutz, Kohl, Stumpp, Briand, Forrer, Grutter and Pluckthun, Nat Biotechnol 22: 575-82, 2004; Zahnd, et al., Nat Methods 4: 269-79, 2007). The pools after these four initial rounds were screened for binders to human IL4 by crude extract ELISA and a crude extract cellular HEK/STAT6 functional assay. The selected binders were of nanomolar affinity (KD), as revealed by SPR measurements of single clones (data not shown).
To specifically enrich higher affinity AR proteins, two off-rate selection rounds with increased selection stringency, each followed by one or two standard selection rounds, were performed after the first four rounds (Zahnd, et al., J Biol Chem 281: 35167-75, 2006).
Following this sixth round of ribosome display, single clones obtained from these rounds were screened by crude extract cellular HEK/STAT6 functional assay, to identify the most potent candidates. The pool of selected AR proteins was subcloned into a T5 promoter based vector for expression. Following expression, crude lysates from 200 individual AR proteins were assessed for binding to recombinant IL4 by ELISA and inhibition of IL4 dependent STAT6 phosphorylation in HEK-STAT6 cells. Lysates were prepared by transforming plasmids encoding specific AR proteins into E. coli XL-1 blue cells. A 1.2 ml starter culture in Luria Bertani medium (LB) containing 50 ug/ml ampicillin and 1% glucose was inoculated with a single colony. The starter cultures were incubated overnight at 37° C., shaking at 220 rpm. On the next day, a part of the overnight culture was used as inoculum of 0.9 ml LB. Protein expression was induced using 500 uM isopropyl β-D-1-thiogalactopyranoside (IPTG). Cultures were incubated 4 hours at 37° C., shaking at 220 rpm. Cell pellets were harvested by centrifugation and lysed with 50 μl B-Per solution (Pierce). These lysates were diluted with PBS before using them in subsequent screening assays.
In order to assess the binding to IL4, each crude extract of the lysates containing a binding protein was added to Maxisorp ELISA plate pre-coated with neutravidin and biotinylated IL4 and incubated for 1 hour. After extensive washing, bound AR proteins were detected using an anti-RGS-His6-HRP conjugate (34450, Qiagen).
In parallel, the same 200 single clone E. coli lysates were subjected to a cellular inhibition assay. The activity of each crude extract sample was assayed for their ability to inhibit IL4 dependent activation of STAT6 using HEK-Blue STAT-6 cells (Invivogen™ SanDiego, Calif.). Stimulation of HEK-Blue STAT-6 cells was carried out as follows: on Day 1, cells were plated in 96-well cell culture plates at a density of 2.5×105/ml in 100 μl of cell culture media (DMEM with 4.5 g/L Glucose (11995, Gibco/Invitrogen, Carlsbad, Calif.), 10% Heat Inactivated FBS (10082, Gibco/Invitrogen, Carlsbad, Calif.), 10 μg/mL Blasticidin S, a peptidyl nucleoside antibiotic active (Invivogen), and 100 μg/mL Zeocin™, a copper-chelated glycopeptide antibiotic produced by Streptomyces CL990 (Invivogen) for 8 hours. On the same day, 100 μl of cell culture media containing the diluted AR protein crude extracts premixed with 50 μg/ml (3.3 pM) human IL4 (Peprotech) were added. The plates were incubated overnight at 37° C. and 5% CO2. To measure secreted embryonic Alkaline™ phosphatase, 30 μl of each cell supernatant was mixed with 80 μl of Quanti-Blue™ (Invivogen) in a clear 96-well plate. The plate was incubated for 1 hour at 37° C. and absorbance at 620 nm was read using a plate reader.
As the initial screen of 200 clones produced only a few AR proteins that bound with high affinity to IL4 and effectively inhibited signaling, single clone crude extracts of 5100 more AR proteins obtained following additional rounds of ribosome display with off-rate selection (rounds 7, 8, and 9) were tested for their ability to inhibit IL4 dependent STAT6 phosphorylation as described above. The activity of these clones were compared in this assay to a benchmark AR protein, clone C06—28E5, found in the first round screen to bind to IL4 with an apparent affinity of 50 pM as revealed by SPR and inhibit STAT6 production with an IC50 of 3 pM in the presence of 3 pM IL4. Thus, comparing subsequently selected clones to the test values of the benchmark allowed for expedient selection of additional high potency candidates.
Based on the results of the STAT6 phosphorylation screen, 22 AR proteins (SEQ ID NO: 9-30) that showed inhibition of IL4 with better or equal activity compared to that of the benchmark were selected for further characterization.
The selection of IL13-binding specific ankyrin repeat proteins was performed by ribosome display (Hanes and Plückthun, loc. cit.) using a human IL13 variant (R130Q) target protein. The IL13 R130Q variant (R110Q of SEQ ID NO: 1) is a variant of human IL13 that has been linked to atopic patients (Arima et al. J. Aller. Clin. Immunol. 109:980-987, 2002).
Selection and Screening of Human IL13 Binding Proteins:
In total, 6 ribosome display selection rounds on human IL13 R130Q (Peprotech) were performed in solution with both the N2C and N3C AR libraries. The first four rounds of selection employed standard ribosome display selection, using decreasing target concentration and increasing washing stringency to increase selection pressure from round 1 to round 4 (Binz et al. Nature Biotech 22:575-582, 2004). After four rounds of panning, the pools were screened for binders to human IL13 in the crude extract using an ELISA format. The selected binders were of nanomolar affinity, as revealed by BIAcore measurements of single clones (data not shown).
Following the fourth round of ribosome display selection, the pool of selected binding proteins were cloned into a T5 promoter based expression vector. Following expression, 200 individual binding proteins were assessed for binding as crude extracts to human L-13 R130Q captured on neutravidin plates. Of these, 32 binding proteins with the highest binding signal by ELISA were expressed and purified by immobilized metal ion affinity chromatography (IMAC) and screened for their ability to inhibit IL13R13Q dependent binding to human IL13Rα2-Fc fusion using an ELISA format: binding protein candidates (10 nM or 100 nM final concentration) were pre-incubated with 10 nM biotinylated human IL13 R130Q for 30 minutes, the binding protein-IL13 mixture was added to a Maxisorp ELISA plate pre-coated with IL13Rα2-Fc (R&D Systems) and incubated for 15 minutes to capture free biotinylated IL13 and detected using streptavidin-horse radish peroxidase. The relative amount of inhibition produced by the binding protein was assessed by comparing the signal measured for 10 nM biotinylated IL13 with no binding protein added. Based on the results of this screening assay at 10 nM binding protein, which was equimolar to the IL13R130Q, IL13 binding protein 2F1 was chosen as a benchmark for all further screenings.
To identify higher affinity human IL13 binders, the output from the fourth round of standard ribosome display screening (above) was subjected to an off-rate selection round with increased selection stringency. A final standard selection round was performed to amplify and recover the off-rate selected binding proteins. Again, crude extracts were screened for binding to IL13 as described above and the signal relative to 2F1 binding protein was assessed. To enable differentiation between high and low affinity binding proteins, the dilution of the crude extracts of 1:10 was chosen because it allowed clear differentiation of binding proteins with stronger binding to IL13 than the benchmark binding protein 2F1. About 700 binding protein clones were assayed in this manner.
In parallel, crude extracts screened for binding were evaluated for their ability to inhibit IL13 dependent activation of STAT6 using HEK-Blue STAT-6 cells (InVivogen, SanDiego, Calif.). To enable differentiation between high and low affinity binding proteins, an optimal dilution of the crude extract (1:5200) was selected. In the HEK-Blue STAT-6 cells, IL13 activates the IL13Rα1: IL4R complex (Type 2 receptor) to induce secretion of an embryonic alkaline phosphatase (SEAP) reporter gene via the STAT-6 signaling pathway. Stimulation of HEK-Blue STAT-6 cells using crude protein extracts was carried out as follows: on Day 1, cells were plated in 96-well cell culture plates at a density of 2.5×105/ml in 100 uL of cell culture media (DMEM with 4.5 g/L Glucose (11995, Gibco/Invitrogen, Carlsbad, Calif.) with 10% Heat Inactivated FBS (10082, Gibco/Invitrogen, Carlsbad, Calif.), 10 μg/mL Blasticidin (Invivogen), and 100 μg/mL Zeocin (Invivogen)) for 24 hours. On Day 2, 100 μL of cell culture media containing the appropriate concentration of AR protein premixed with 1 ng/mL (80 pM) human IL13 (Peprotech) was added to the cells. The plates were incubated for 24 hours at 37° C. and 5% CO2. To measure secreted embryonic alkaline phosphatase, 40 μL of each cell supernatant was mixed with 160 μL of Quanti-Blue (Invivogen) in a clear 96-well plate. The plate was incubated for 2 hours at 37° C. and absorbance at 650 nm was read using a plate reader.
By evaluating 700 tested crude extracts, 94 binding proteins were identified as showing higher binding and inhibition activity than the benchmark binding protein 2F1. HEK/STAT6 and ELISA screening data were plotted against each other to identify binding proteins that performed better than the benchmark binding protein 2F1 in both screening and activity assays (
The 22 AR proteins selected for further characterization were expressed using a T5-promoter based system in the cytoplasm of E. coli and purified via immobilized metal ion affinity chromatography (IMAC). Briefly, AR proteins were transformed in E. coli XL-1 blue cells and used to inoculate a 5 ml starter culture in Luria Bertani medium (LB) containing 50 μg/ml ampicillin and 1% glucose. The starter cultures were incubated overnight at 37° C., shaking at 220 rpm. On the next day, the overnight culture was used as inoculum of 50 ml LB. At a cell density of OD600=0.7, protein expression was induced using 500 μM isopropyl β-D-1-thiogalactopyranoside (IPTG). Cultures were incubated 4 hours at 37° C., shaking at 220 rpm. Cell pellets were harvested by centrifugation. Cells were ruptured by the addition of 1 mg/ml lysozyme, 50 KU/ml DNAse I and sonification for 30 minutes on ice. The insoluble fraction was removed by centrifugation. The clarified supernatant was filtered using 0.22 μM filters. These supernatants were loaded on columns packed with 250 μl Ni-NTA superflow resin (Qiagen). Purification was carried out following the instructions of the manufacturer. 20 ml Tris buffered saline (TBS) containing 20 mM imidazole and 10% glycerol was used as wash buffer, and 600 TBS containing 250 mM imidazole was used to elute AR proteins from the column.
SEC of Selected Human IL4 Binding AR Proteins
The 22 purified AR protein samples were analyzed for aggregation by size exclusion chromatography (SEC) using a Superdex 75 5/150 column (GE healthcare) and a PBS pH 7.4 mobile phase. 10 uL of each sample was injected per run with a flow rate of 0.3 mL/min. The column was calibrated using conalbumin, ovalbumin, carbonic anhydrase, ribonuclease A, and aprotinin protein standards. Elution of the AR proteins from the column was monitored by absorbance at 214 nm. The elution profiles of the samples were evaluated to identify AR protein candidates that eluted predominantly as monomers as evidenced by a single peak eluting at the appropriate volume for a 15 kDa protein (for N2C library) (18 kDA protein for N3C library) determined using MW standards. The results of biophysical properties of characterized IL4-binding AR proteins are summarized in Table 1.
Affinity Determination of Purified Hit AR Proteins
Purified binders selected as “hits” were ranked by their affinity on a ProteOn XPR-36 instrument (Bio-Rad). ProteOn is an optical biosensor instrument that measures protein-protein interactions in real time, based on Surface Plasmon Resonance technology similar to Biacore (GE). A rapid experimental protocol was performed as follows: On a GLC sensor chip (Bio-Rad), Neutravidin (Thermo Scientific) was covalently immobilized to a density of >5000 RU using amine coupling chemistry as described by the manufacturer. On one flow cell, biotinylated IL4 (Peprotech) was immobilized to a level of 250 RU, while another flow cell was used as reference, with neutravidin immobilized only. From each of the purified AR proteins, three different concentrations (25, 12.5, 6.25 nM) were analyzed, and kinetic parameters were calculated by fitting using a Langmuir 1:1 model. The ka, kd, and KD obtained for each AR protein from these measurements are presented in Table 1, where E is base 10. The retrieved values were used to rank the AR proteins by their affinity.
AR Protein Composition
The compositions of the 22 AR proteins represented as expressed proteins are given in SEQ ID NO: 9-30. It was found that the 22 AR proteins represented 51 unique AR modules as given by SEQ ID NO: 31-81. In some instances, mutations in the N-cap module occurred including (based on SEQ ID NO: 2) D1N, K5E, R11S, A12V, R19H, V28A, and A30V alone or in combination. One AR protein, C06—26H2 was found to have G16R in the C-cap (SEQ ID NO: 3).
The specific sequences of the AR units are shown in the sequence tables for each of the modules and all 22 IL4 binding proteins.
The compositions of each of the AR protein binding domains are listed below in Table 2 as the corresponding SEQ ID NO: according to the formula AR1-AR2-AR3 or AR1-AR2-AR3-AR4.
In comparing the 22 AR1 modules represented by 15 unique sequences (SEQ ID NO: 31-46), there was a preference for T at X1, for D at X2 of the AR sequence motif, for W at X3, and D at X6. The usage of pairs of amino acids at adjacent variable positions (X2X3 and X5X6) was also tabulated as shown below (Table 3). DW was the most frequently occurring doublet for X2X3 and TD was the most frequently occurring doublet for X5X6. Thus, the AR1 module can be represented by the amino acid sequence
X1D-[DW]-GX4TPLHLAA-[TD]-GHLEIVEVLLKX7GADVNA, wherein X1 and X4, are chosen from residues as shown in Table 4 and X7 may be H, N, or Y (C-AR1, SEQ ID NO: 82). Alternatively, the AR1 motif may be chosen from an amino acid sequence represented by the formula:
TD-[DW]-GX4TPLHLAA-[TD]-GHLEIVEVLLKX7GADVNA, wherein X4 is chosen from the residues listed in Table 4 and X7 may be H, N, or Y (F-AR1, SEQ ID NO: 85).
In comparing the 22 AR2 modules which represented by 15 unique sequences (SEQ ID NO: 47-61), there was no dominant residue (more than 50% frequency) at any of X1, X2, X3, X4, X5, or X6 of the AR sequence motif. The usage of pairs of amino acids at adjacent variable positions (X2X3 and X5X6) was also tabulated as shown below (Table 4). AM was the most frequently occurring doublet for X2X3 and VY was the most frequently occurring doublet for X5X6. Thus, the AR2 module can be represented by the sequence:
X1D-[X2X3]-G X4TPLHLAA-[X5X6]-GHLEIVEVLLKX7GADVNA wherein X1, X2X3, X4, and X5X6 are chosen from the residues shown in Table 4 and X7 may be H, N, or Y (C-AR2, SEQ ID NO: 83). Alternatively, the AR2 motif may be chosen from a sequence represented by the formula:
D-[AM]-GX4TPLHLAA[VY]-GHLEIVEVLLKX7GADVNA where X1 and X4 are chosen from the residues in Table 4 and X7 may be H, N, or Y (F-AR2, SEQ ID NO: 86).
In comparing the 22 AR3 modules which represented by 17 unique sequences (SEQ ID NO: 62-78), there was no dominant residue (more than 50% frequency) at any of X1, X2, X3, or X6 of the AR sequence motif, however, X4 and X5 was most frequently F and at least one of X5 or X6 was frequent F or Y. The usage of pairs of amino acids at adjacent variable positions (X2X3 and X5X6) was also tabulated as shown below (Table 5). FY was the most frequently occurring doublet for X5X6. Thus, the IL4-binding AR3 module can be represented by the amino acid sequence
X1D-[X2X3]-G-F-TPLHLAA-[X5X6]-GHLEIVEVLLKX7GADVNA, wherein X1 and X2X3, and X5X6 are chosen from the residues in Table 5 and X7 may be H, N, or Y (C-AR3, SEQ ID NO: 84). Alternatively, the AR3 motif may be chosen from an amino acid sequence represented by the formula
X1D-[X2X3]-G-F-TPLHLAA-[FY]-GHLEIVEVLLKX7GADVNA, wherein X1 and X2X3 are chosen from the residues listed in Table 5 and X7 may be H, N, or Y (F-AR3, SEQ ID NO: 87).
There were only 3 AR4 modules (SEQ ID NO: 79-81) and no consensus or focused sequence formula was adopted for this set.
Neutralization of IL4 Dependent STAT6 Phosphorylation by Purified AR Proteins
The activity of each purified AR protein was assayed for their ability to inhibit IL4 dependent activation of STAT6 using HEK-Blue STAT-6 cells as described above. Full inhibition curves were assessed for each candidate and absorbance data were plotted as a function of AR protein concentration to a sigmoidal dose response using the PRISM software (GraphPad PRISM) to determine IC50 values with 3.3 pM IL4. IC50 values obtained for these AR proteins ranged from 1.3 to 235 pM as are presented in Table 6.
Competition Binding with IL4RA for IL4 Binding
For biotinylation of IL4, recombinant human IL4 (Peprotech) was biotinylated at a 4:1 ratio using EZ-Link NHS-LC-Biotin (Pierce, #21336) for 2 hours at RT. The protein was dialyzed in PBS overnight to remove excess biotinylation reagent. Competition binding for cynomologous IL4 (SEQ ID NO: 5) was performed using the isolated protein biotinylated in the same manner.
AR protein inhibition of IL4 binding to IL4 RA was assessed using IL4 RA-Fc (R&D Systems), comprising the Gly24-His232 which represents the ECD (SEQ ID NO: 5) fused to a human IgG1-Fc and therefor a disulfide linked homodimer. The protein was conjugated to carboxylated Luminex microspheres according to the manufacturer's protocol. For neutralization experiments, 5000 IL4RA-Fc conjugated beads in 50 μl were added to each well of a 96-well filter plate (Millipore). Biotinylated human IL4 was mixed with an appropriate dilution of AR protein in Luminex Assay Buffer (PBS, 1% BSA, pH 7.4) to give a final concentration of 67 pM IL4. The plate was incubated for 1 hour at RT in the dark on a plate shaker, set to shake vigorously to avoid bead aggregation. The plate was washed twice with 150 μl of wash buffer (PBS, 0.1% BSA, pH 7.4, 0.05% Tween-20) using a vacuum manifold followed by the addition of 50 μl of Streptavidin PE at 25 μg/ml and incubated at RT for 20 minutes. The plates were washed again and 150 μl of sheath fluid was added and the plate was placed on the shaker for 5 minute. Plates were read using a Luminex® 100 system; data were plotted as a function of AR protein concentration. IC50 values were determined by fitting the data to the equation for sigmoidal dose response using PRISM software (GraphPAD PRISM) (Table 6).
IL4-Dependent TARC Production
TARC is a key regulator of Th2-mediated inflammation in allergic asthma. Stimulation of A549 cells by IL4 in vitro leads to the production of TARC. This assay complements the HEK-STAT6 assay described above as it demonstrates the ability of an inhibitor to block IL4 signaling in primary cells, Each AR protein was assayed for inhibition of IL4 dependent TARC production in A549 cells as follows: on Day 1 cells were plated overnight in 96-well culture plates at a density of 2.5×105/ml in 100 μl of cell culture media (alphaMEM with GlutaMax, +10% heat-inactivated FBS, 1× Sodium Pyruvate, and 1×MEM NEAA (Gibco). This media also serves as the assay media. On Day 2 cells were washed once with 200 μl of culture media and stimulated with 200 μl of culture media containing 200 ng/ml (11 nM) recombinant human TNF-alpha and 67 pM recombinant IL4 premixed with appropriate concentration of AR protein. The plates were incubated for 24 hours at 37° C. and 5% CO2. Supernatants were harvested and stored at −80° C. for further analysis. CCL17/TARC Duo Set ELISA kit (RandDSystems) was used to quantify the amount of TARC in the samples using the manufacturer's protocol and a 1:5 dilution of the samples. Data were plotted as a function of AR protein concentration and fit to a sigmoidal dose response using the PRIZM software (GraphPad PRISM) to determine IC80 values (Table 6).
STAT6 Signaling in RA-1 Cells
Each AR protein was assayed for inhibition of IL4 induced STAT6 signaling in STAT6-bla RA-1 cells. The CellSensor® STAT6-bla RA-1 Cell Line contains a beta-lactamase reporter gene under control of the STAT6 response element stably integrated into Ramos-1 (RA-1) cells. In contrast to the HEK-Blue STAT6 cells described above which signal through Type II complexes, RA-1 cells signal through Type I complexes and can be used to confirm the inhibition of IL4 stimulation through Type I complexes.
The assays were performed as recommended by the manufacturer, Invitrogen (Cat. No. K1243). On Day 1, RA-1 cells were plated in black 96-half area well cell culture plates (with clear bottom) at a density of 937,500 cells/ml in 32 μl of Assay Buffer. For cell-free control wells, 32 μl of assay buffer was added. A CD40 solution was prepared (50 μl of stock at 100 μg/ml to 950 assay buffer) and 4 μl was added to each well (final concentration was 556 ng/mL) to ensure that cells respond to IL4. The cells were spun at 14×g for 30 sec and placed in 37° C., 5% CO2 for 16 hours. On Day 2, 4 μl of assay buffer was added to the cells containing a 10× concentration for the range of hIL4 to obtain the EC80. For inhibition studies, a 10× inhibition solution containing the AR protein was premixed with a 10×hIL4 at the EC80 and then added to the cells. The concentration of hIL4 was 20.8 pM. The plates were spun at 14×g for 30 sec and placed in 37° C., 5% CO2 for 5 hours. Thereafter, 8 μl of the Live BLAzer-FRET B/G (CCF4-AM) solution was added to each well (composed of 6 μl of solution A, 60 μl of Solution B, and 934 μl of solution C) and spun at 14×g for 30 sec. The plates were protected from light and incubated at room temperature for 2.5 hours. Plates were measured on the Envision Machine with bottom read capabilities using an excitation filter at 409/20 nm and two emission filters: one at 460/40 nm and one at 530/30 nm. A dual mirror was also used. To analyze the fluorescence reading, the background was subtracted (values from the cell-free wells) from both 460 nm and 530 nm and a 460/530 ratio was determined. The ratio was then plotted against concentration in the GraphPad PRIZM software to obtain an IC50 value.
The composite of biophysical and biochemical data described in Example 2 (Table 1) were used to select 9 AR protein molecules, C06—13A10, C06—20B8, C06—28E5, C06—42A11, C06—44C12, C06—44F6, C06—53G6, C06—43G2, and C06—6E9 for optimization. These AR proteins were chosen because each was found to be monomeric by SEC, able to bind to recombinant IL4 with a KD<9.7E-11, inhibit IL4-dependent signaling in HEK-STAT6 cells with a potency >67 pM, and inhibit the binding of recombinant IL4 to the IL4 receptor with an IC50<66 pM. The ten lead AR proteins were subjected to further cell based assays to confirm the inhibition of IL4-dependent signaling in additional cell based assays.
The AR proteins C06—44C12, C06—53G6, and C06—28E5 were selected for optimization.
Expression and Purification of Binding Protein Candidates
The 94 binding protein candidates selected for further characterization were expressed using a T5-promotor based system which allows for E. coli cytoplasmic expression and purified via immobilized metal ion affinity chromatography (IMAC). Briefly, E. coli XL-1 Blue cells were transformed with binding protein expression plasmids and used to inoculate a 5 ml starter culture in Luria Bertani medium (LB) containing 50 μg/mL ampicillin and 1% glucose. The starter cultures were incubated overnight at 37° C., shaking at 220 rpm. Overnight cultures were used to inoculate 50 mL LB containing 50 μg/ml ampicillin. At a cell density of OD600=0.7, protein expression was induced using 500 μM isopropyl β-D-1-thiogalactopyranoside (IPTG). Cultures were incubated 4 hours at 37° C., shaking at 220 rpm. Cell pellets were harvested by centrifugation. Cells were ruptured by the addition of 1 mg/mL lysozyme and sonification for 30 minutes on ice. The insoluble fraction was removed by centrifugation. The clarified supernatant was filtered using 0.22 μM filters. These supernatants were loaded on columns packed with 250 μL Ni-NTA superfow resin (QIAgen). Purification was carried out following the instructions of the manufacturer. 20 mL Tris buffered saline (TBS) containing 20 mM imidazole and 10% glycerol was used as wash buffer, and 600 μL TBS containing 250 mM imidazole and 10% glycerol was used to elute the binding proteins.
SEC of Selected Human IL13 Binding Proteins
The 94 binding protein samples were analyzed for aggregation by size exclusion chromatography (SEC) using a TOSOH G2000SWXL column and a PBS pH 7.4 mobile phase. 20 μL of each sample was injected per run with a flow rate of 0.2 mL/min. The column was calibrated using conalbumin, ovalbumin, carbonic anhydrase, ribonuclease A, and aprotinin protein standards. Elution of the binding proteins from the column was monitored by absorbance at 214 nm. The elution profiles of the samples were evaluated to identify binding protein candidates that eluted predominantly as monomers.
Thermal Stability of IL13 Binding Proteins:
The melting temperatures of the selected IL13-binding protein samples were measured using Thermofluor technology (Pantoliano et. al. J Biomol Screening: 6:429-440, 2001). Thermofluor is a high throughput kinetic measurement of protein unfolding as a function of heat. As samples are heated, ANS in the sample buffer binds to hydrophobic regions generally buried in the folded molecule inducing an increase in dye fluorescence. After purification (above), each sample was exchanged into PBS buffer pH 7.4 using PD Multi-trap G25 resin (GE Healthcare) and the concentration estimated using the absorbance at 280 nm. Sample concentrations ranged from 1-50 μM. Binding protein unfolding was monitored between 37-95° C. with fluorescence measured every 0.5° C. in continuous ramp mode. Melting temperatures measured ranged from 54° C. to >95° C. for these samples. No melt was detected for several samples, indicating either that the stability is greater than 95° C. or that the protein concentration was too low to accurately measure the fluorescence (data not shown).
Neutralization of IL13 Dependent Stat6 Phosphorylation
The activity of each purified binding protein was assayed for their ability to inhibit IL13 dependent activation of STAT6 using HEK-Blue STAT-6 cells as described above. Full inhibition curves were assessed for each candidate and absorbance data were plotted as a function of binding protein concentration to a sigmoidal dose response using the PRIZM software (GraphPad PRIZM) to determine IC50 values (data not shown).
Single Point Affinity Screening
The affinity of all purified binding proteins was assessed by ProteOn (BioRad) using a rapid affinity screening protocol as follows. On a GLC sensor chip (Biorad), neutravidin was covalently immobilized to a density of >5000 RU using amine coupling chemistry as described by the manufacturer. On one flow cell, biotinylated IL13 R130Q (Peprotech) was immobilized to a level of 250 RU; a second flowcell was used as reference with only neutravidin immobilized. From each of the purified binding proteins, a concentration of 50 nM was analyzed, and kinetic parameters were estimated by fitting using a Langmuir 1:1 model. The retrieved values were used to rank the binding proteins in terms of apparent affinity. These binding proteins had an on-rate (ka) of between 1.7 and 9.6×105 1/M−s and an off-rate (kd) ranging from 1.3×10−5 to 1.1.×10−4 1/s providing a KD of 2.1×10−11 to 1.7×10−8 M.
Based on the initial screens, 16 lead molecules were chosen for further characterization. A panel of 16 lead binding proteins which exhibited largely monomeric elution from an SEC, had an affinity (KD)<1.5 nM, inhibited IL13 dependent STAT6 phosphorylation with an IC50 better than 100 pM and had a Tm of greater than 50° C. by Thermofluor analysis was selected for larger scale expression, purification and characterization as described below.
Expression
E coli XL-1 Blue cells were transformed with binding protein expression plasmids. A single colony was picked and grown at 37° C. in 500 mL TB media containing carbenicillin. When the culture density reached an A600 of between 0.7 and 1.0 unit, expression was induced with 0.4 mM IPTG and incubated for an additional 4 h at 37° C. Bacterial pellets were recovered by centrifugation and stored frozen until use. Frozen bacterial pellets were thawed and lysed in 50 mM sodium phosphate pH 7.5, 500 mM sodium chloride, 20 mM imidazole and containing an EDTA-free protease inhibitor cocktail. Resuspended pellets were sonicated and bacterial debris was collected by centrifugation in a JA-17 rotor at 17,000×g for 30 min. Soluble lysates were filtered and 2 mL of Ni-NTA resin (Qiagen) was added to each lysate followed by slow stirring for at least 1 h at 4° C. to capture the His-tagged binding proteins. The resin-containing lysate was poured into a column and washed with 8 column volumes of 50 mM sodium phosphate pH 7.5, 500 mM sodium chloride and 20 mM imidazole. The His-tagged protein was eluted from the resin with 8 column volumes of 50 mM sodium phosphate pH 7.5, 500 mM sodium chloride containing 500 mM imidazole. Further purification was achieved by size exclusion chromatography using a Superdex 200 26/60 column equilibrated in PBS pH 7.0.
Thermal Stability of Binding Protein Leads
The thermal stabilities of the 16 binding protein candidates were measured by differential scanning calorimetry (DSC). For Tm measurements, DSC is a more precise analytical method than the Thermoflour analysis used for high throughput screening. Each sample was dialyzed extensively against PBS pH 7.4 and diluted to a concentration of 1 mg/mL. Melting temperatures were measured for these samples using a model VP DSC instrument equipped with an autosampler (Microcal). Samples were heated from 10° C. to 95° C. at a rate of 1° C. per minute. A buffer only scan collected between each sample scan was subtracted from the sample scan to allow calculation a baseline for integration. Data were fit to a two state unfolding model and results are presented in Table 7. The binding proteins analyzed expressed a wide range of melting temperatures from 48° C. to 85° C.
Binding Affinity for Human IL13
Recombinant human IL13 (Peprotech) was minimally biotinylated on ice using sulfo-NHS-LCLC-Biotin and desalted into the experimental running buffer containing 10 mM HEPES, 150 mM NaCl, pH 7.4, 0.01% Tween-20, and 0.1 mg/mL BSA. Biotinylated IL13 was captured at three different surface densities (from about 150, 50, and 25 RU) onto three different BIAcore SA (streptavidin) sensor chips. Each binding protein sample was tested at 40 nM as the highest concentration in a 3-fold dilution series over the three different density IL13 surfaces. The dissociation phase for the highest concentration of the binding protein sample was monitored for one hour. The response data from each of the different density surfaces was globally fitted in order to extract estimates of the kinetic and affinity constants which are provided in Table 7 below.
Neutralization of IL13 Dependent Activities
The activity of each binding protein sample was assayed for inhibition of IL13 dependent STAT6 phosphorylation as described above using 80 pM IL13. Data are shown in Table 7. Likewise, each binding protein sample was assayed for the ability to inhibit STAT6 phosphorylation stimulated by IL13 from cynomologous monkey in order to verify cross reactivity with this species for future toxicology and pharmacokinetic studies. Recombinant cyno IL13 was expressed and purified from E. coli as a SUMO-tag fusion protein. The SUMO-tag was subsequently enzymatically cleaved from IL13 in preparation for inhibition assays. Neutralization of cyno IL13 was assayed as follows: on Day 1, cells were plated in 96-well cell culture plates at a density of 2.5×105 per ml in 100 uL of cell culture media (DMEM with 4.5 g/L Glucose (11995, Gibco/Invitrogen, Carlsbad, Calif.) with 10% Heat Inactivated FBS (10082, Gibco/Invitrogen, Carlsbad, Calif.), 10 μg/mL Blasticidin (Invivogen), and 100 μg/mL Zeocin (Invivogen)) for 24 hours. On Day 2, 100 μL of cell culture media containing the appropriate concentration of AR protein premixed with 1 ng/mL (80 pM) recombinant cyno IL13 was added to the cells. The plates were incubated for 24 hours at 37° C. and 5% CO2. To measure secreted embryonic alkaline phosphatase, 40 μL of each cell supernatant was mixed with 160 of Quanti-Blue (Invivogen) in a clear 96-well plate. The plate was incubated for 2 hours at 37° C. and absorbance at 650 nm was read using a plate reader. Results of cyno IL13 inhibition are presented in Table 8 below.
IL13 Dependent TARC Production
TARC(CCL17) release from A549 cells (a human lung carcinoma-derived cell line) can be stimulated by IL13.
Each binding protein was assayed for inhibition of IL13 dependent TARC production in A549 cells as follows: on Day 1 cells were plated overnight in 96-well culture plates at a density of 1.0×106/ml in 200 μL of cell culture media (alphaMEM with GlutaMax, +10% heat-inactivated FBS, 1× Sodium Pyruvate, and 1×MEM NEAA (Gibco)). This media also serves as the assay media. On Day 2 cells were washed once with 200 μL of culture media and stimulated with 200 μL of culture media containing 200 ng/mL (11 nM) recombinant human TNF-alpha and 1 ng/mL (80 pM) recombinant IL13 premixed with appropriate concentration of binding protein. The plates were incubated for 24 hours at 37° C. and 5% CO2. Supernatants were harvested and stored at −80° C. for further analysis. A kit was used to measure human CCL17/TARC Duo Set ELISA (R&D Systems) in the samples according to the manufacturer's protocol and where the samples were used at a 1:5 dilution. Data were plotted as a function of binding protein concentration and fit to a sigmoidal dose response using the PRIZM software (GraphPad PRIZM) to determine IC50 values (Table 8 below).
IL13:IL13Rα2 Binding
Binding protein inhibition of IL13 binding to Rα2 was assessed using IL13Rα2-Fc (R&D Systems) conjugated to carboxylated Luminex microspheres according to the manufacturer's protocol. For biotinylation of IL13, recombinant human IL13 R130Q (Peprotech) was biotinylated at a 4:1 ratio using EZ-Link NHS-LC-Biotin (Pierce, #21336) for 2 hours at RT. The protein was dialyzed in PBS overnight to remove excess biotinylation reagent. For neutralization experiments, 5000 IL13 Rα2-Fc conjugated beads in 50 μl were added to each well of a 96-well filter plate (Millipore). 50 μl of biotinylated human IL13 at 1 ng/ml (80 pM) was mixed with an appropriate dilution of binding protein in Luminex Assay Buffer (PBS, 1% BSA, pH 7.4). The plate was incubated for 1 hour at RT in the dark on a plate shaker, set to shake vigorously to avoid bead aggregation. The plate was washed 3 times with 150 μl of wash buffer (PBS, 1% BSA, pH 7.4, 0.05% Tween-20) using a vacuum manifold followed by the addition of 50 μl of Streptavidin PE at 25 μg/ml and incubated at RT for 20 minutes. The plates were washed again and 100 μl of sheath fluid was added and the plate was placed on the shaker for 1 minute. Plates were read using a Luminex® 100 system; data were plotted as a function of binding protein concentration. IC50 values were determined by fitting the data to the equation for sigmoidal dose response using PRIZM software (GraphPAD PRIZM). The inhibition constants for the lead binding proteins are listed in Table below.
AR Protein Compositions
The sequences of the ankyrin repeat domains of the 2F1 and 16 lead anti human IL13 binding proteins where each binding protein follows the format of (N-Cap)-(AR)n—(C-Cap) where n=2 or 3 were analyzed.
It was found that the 2F1 and the additional 16 binding proteins represented 46 distinct AR modules as listed in the sequence tables below where a dot indicates that the amino acid present at its position for a certain AR corresponds to the corresponding amino acid of the AR repeat motif (SEQ ID NO: 1). In a few cases, where framework mutations were observed in the selected binding protein sequence they are noted. In a few cases, deletions arose during the ribosome display selection process; these deletions are noted with a dash (-). Binding protein 10A6 contains only 2 ARs. In all cases, the C-Cap sequence starts immediately after residue 33 of the last AR.
The composition of each of the binding domain tandem AR units (AR1-AR2-AR3) of each binding protein are listed below (Table 9 below)
In comparing the AR1 modules which represented by 17 unique sequences (SEQ ID NO: 9-25) (Table 10 below), there was a preference for Y or F at position 4 (X3) of the motif, S at position 6 (X4), Rat position 14 (X5), H at position 15 (X6), and at position 27 (X7) H or Y.
Thus, the IL13 binding AR1 module can be represented by the formula
X1DX2-[F,Y]-GSTPLHLAA-RH-GHLEIVEVLLKX7GADVNA, wherein X1 is chosen from residues as shown below and X7 may be H, N, or Y (AR1-C, SEQ ID NO: 156). Alternatively, the AR1 motif may be chosen from an amino acid sequence represented by the formula:
TDYGSTPLHLAARHGHLEIVEVLLKX7GADVNA, wherein X7 may be H, N, or Y (AR1-F, SEQ ID NO: 157).
In comparing the 17 AR2 modules which represented by 17 unique sequences (SEQ ID NO: 127-143) (Table 11 below), there was no dominant residue (more than 50% frequency) at X1, however, at the randomized positions X3, X4, X5 and X6 of the AR sequence motif there was a most frequently used amino acid. The usage of pairs of amino acids at adjacent variable positions (X2X3 and X5X6) was also tabulated as shown below. FI was the most frequently occurring doublet for X2X3. Thus, the IL13-binding AR2 module can be represented by the formula (wherein the bracketed residues are alternate amino acids for that position):
X1DFIG DTPLHLAAY-X6-GHLEIVEVLLKX7GADVNA, wherein X1 is chosen from N, T, A, D, K, E, H, M, and F; X6 may be H or R; and X7 may be H, N, or Y (AR2-C, SEQ ID NO: 158). Alternatively, the AR2 sequence may be chosen from an amino acid sequence represented by the formula
In comparing the 16 AR3 modules which represented by 12 unique sequences (SEQ ID NO: 144-155), there was no dominant residue (more than 50% frequency) at any of X1, X2, X5, or X6 of the AR sequence motif, however, X3 was most frequently T, and X4 was most frequently E. The usage of pairs of amino acids at adjacent variable positions (X2X3 and X5X6) was also tabulated as shown below. IT was the most frequently occurring doublet for X2X3. SM was the most frequently occurring doublet for X5X6. Thus, the IL13-binding AR3 module can be represented by the amino acid sequence
X1D-X2 TG-E-TPLHLAA-[X5X6]-GHLEIVEVLLKX7GADVNA, wherein X1 and X2, are chosen from the residues in Table 12 below, and X5X6 are selected from the pair SM, HL, and YH; and X7 may be H, N, or Y (AR3-C, SEQ ID NO: 160). Alternatively, the AR3 motif may be chosen from an amino acid sequence represented by the formula
X1D-IT-G-E-TPLHLAA-SM-GHLEIVEVLLKX7GADVNA, wherein X1 is chosen from the residues listed in Table 12 below and X7 may be H, N, or Y (AR3-F, SEQ ID NO: 161).
To optimize selected IL4-binding AR proteins for large scale manufacturing, formulation, and stability, it was necessary to mutate several residues that were found in the variable residues, X1-X6 of SEQ ID NO: 1. For example, oxidation of purified recombinant proteins can lead to product heterogeneity and loss of activity. In order to reduce the risk of these modifications, Met residues found in the variable sequences were mutated to amino acids of similar chemical makeup or to those found in other sequence related IL4 binding AR proteins. In addition, several mutations were made to eliminate potential sites of immunogenicity as assessed by the presence of potential T-cell epitopes. Finally, random amino acid changes to the ankyrin repeat framework occasionally arose during the PCR steps used for ribosome display selection. Such residues were reverted to the consensus designed ankyrin repeat sequence.
AR protein C06—44C12 was engineered by mutating AR2 position 4 (X3) from Met to Leu in order to avoid potential oxidation in the IL4 binding site. Position 27 (X7) of AR2 and AR3 were mutated from Tyr to Ala in order to eliminate potential T-cell epitopes based on an analysis of neighboring upstream and downstream residues, and remove potential sites of deamidation. Similar mutations were made to C06—28E5, changing position 27 of AR1 and AR2 from Tyr to Ala. For C06—53G6, position 1 of the N-cap was changed from Asn to Asp to restore the ankyrin consensus sequence and position 27 of AR1 was mutated from Tyr to Ala as described above.
After optimization, the AR modules based on the motif formula (SEQ ID NO: 1) for these three proteins were:
The mutations described here were made in a singular or combinatorial manner, in order determine the effect each mutation had on activity. Engineered AR proteins of the sequences designated, were assayed for binding to recombinant IL4, inhibition of IL4 dependent signaling, solubility by SEC, and determination of the melting temperature by DSC (Table 14).
Positional tandem AR units for optimized IL4 binding proteins are represented by the AR formulas:
where the bracketed entries represent the alternative amino acid residue or pair of residues in the three optimized binding proteins which exhibit the desired biologic activities. Therefore, IL4 binding proteins may be constructed from these AR motifs by tandem positioning in the order specified.
IL13 Binding Proteins
Three IL13-binding candidate binding proteins; 7G11, 6G9 and 9F8, were selected for protein optimization for potential large scale manufacturing, formulation, and stability. Each candidate was modified by multiple rounds of site directed mutagenesis.
Mutations were designed that have been found to generally increase the stability of binding proteins, decrease potential immunogenicity, remove the N-terminal HIS tag, enhance the processing of the N-terminal methionine, or remove potential sites of oxidation or deamidation in the putative antigen binding site. The mutations introduced into all final molecules included: N-Cap, position 3 (G to D) to improve the biophysical behavior was introduced to all lead molecule candidates and the terminal residues of the C-cap changed to a di-alanine. In addition, candidates 6G9 and 9F8 were found to contain the 27Asn-Gly28 dipeptide in the modules and therefore, residue 27 was substituted.
Besides the mutations described above which can be applied generically to all binding proteins, a number of mutations specific to the activity of binding proteins 6G9, 7G11, and 9F8 were introduced. Oxidation of purified recombinant proteins can lead to product heterogeneity and loss of activity. In order to reduce the risk of these modifications, Met and Cys residues found in the ankyrin repeat modules of 6G9, 9F8 and 7G11 were mutated to amino acids of similar chemical makeup or to those found in other IL13 binding proteins. Additionally, a number of mutations in the ankyrin repeats of these binding proteins were made to eliminate potential sites of immunogenicity suggested by screening in T-cell activation assays. Finally, for proteins expressed in E. coli, processing of the N-terminal methionine residue can be affected by the amino acid immediately following the N-terminal methionine Hirel et. al. PNAS 86:8247-8251 1989. Total processing of this methionine residue is desirable to increase the homogeneity of the purified product. In the N-Cap, position 1 was changed from aspartic acid to glycine or alanine in order to determine if the N-terminal methionine residue could be efficiently processed when expressed without the HIS tag. A summary of the binding protein specific mutations in specific repeat module positions examined for 6G9, 9F8 and 7G11 is shown in Table 15.
The generic and specific mutations described above were made in singular, or in a combinatorial manner, in order determine the results of each change on activity. Engineered binding proteins were assayed for binding to recombinant IL13, inhibition of IL13 dependent signaling, and determination of the melting temperature by DSC. All of the candidates remained monomeric as determined by SEC. In most cases, the activity and affinity of the mutant were not significantly different from the parent molecule. The properties of each of the three parent and the final optimized lead candidates are shown in Table 15.
Affinity Analysis of Lead Candidates
Complete kinetic data describing binding of various engineered binding protein molecules to human IL13 was measured using a method similar to that described above for the single point affinity analysis. Briefly, streptavidin (Pierce) was immobilized to similar levels (˜1800 RUs) on all six channels of a ProteOn GLC chip via amine coupling (pH 5.0). Biotinylated hIL13 was captured at different surface densities (600˜100 RUs) on different channels. Protein binding was tested starting at 40 nM diluted in a 3-fold concentration series over the different density IL13 surfaces; a buffer sample was injected to monitor the baseline stability. Dissociation phases for all concentrations of each binding protein sample were monitored for one hour at a flow rate of 100 μl/min. Response data for all concentration series from the different density surfaces were globally fit to a 1:1 simple langmuir binding model to extract values of the kinetic (kon, koff) and affinity (KD) constants provided in Table 16.
Purification of Untapped Binding Proteins
Binding proteins without a HIS tag were subcloned into a pET27 vector modified to include a ligase independent cloning site by standard PCR methods and expressed in BL21-GOLD(DE3) E. coli strain (Stratagene). Expression was performed in terrific broth after inducing expression by the addition of 1 mM IPTG at 30° C. Cells were harvested 5 hours after induction by centrifugation and frozen at −20° C. Frozen cell pellets were resuspended in lysis buffer composed of 20 mM histidine pH 6.4 at a concentration of 0.1 g of pellet per mL of buffer. Cell lysis was accomplished by sonication and the lysate cleared by centrifugation at >15,000×g followed by filtration through a 0.45 um filter. Cleared lysates were loaded onto a 5 mL HiTrap Q FF column (GE Healthcare) in lysis buffer. A linear gradient from lysis buffer to buffer B, 20 mM Histidine pH 6.4 with 600 mM NaCl, over 20 column volumes eluted the binding proteins from the Q column. Fractions were analyzed by SDS-PAGE and those containing binding protein were pooled and heated to 70° C. for 20 minutes and then placed on ice for 30 minutes. Precipitated, contaminating proteins were removed by centrifugation. The supernatant of the precipitation step containing the binding protein was then concentrated by ultrafiltration and purified on a Superdex 75 16/60 column (GE Healthcare) with PBS as the mobile phase. The heat step after the initial ion exchange chromatography step was omitted for binding proteins with lower melting temperatures, such as 9F8r3. The biophysical properties and bioactivity measurements for each construct is summarized in Table 16.
Positional tandem AR units for optimized IL13 binding proteins are represented by the AR formulas:
wherein the bracketed entries represent the alternative amino acid residue or pair of residues in the three optimized binding proteins which exhibit the desired biologic activities. Therefore, IL13 binding proteins may be constructed from these AR motifs by tandem positioning in the order specified. The IL13 binding protein according to the formula N-Cap-[AR]n—C-Cap additionally comprises an N-Cap selected from SEQ ID NO: 2 or a variant thereof, such as those exemplified by the formula of SEQ ID NO: 171, and a C-Cap such as SEQ ID NO: 3 or 172 or variants thereof.
The three IL4-binding AR protein molecules described in Example 3 were combined with a previously discovered anti-IL13 AR protein designated 6G9_V1 (SEQ ID NO: 94) in order to produce a bispecific molecule that could block signaling of both human IL13 and IL4. Nucleic acid sequences for each AR protein synthesized to include a sequence encoding for a (GGGGS)4 linker between the 2 AR proteins. Alternative GS linkers with the formula (GGGGS)n may be used to join AR proteins. The length of the linker can be varied to control binding domain availabilty, steric and other properties of the molecule A total of 6 bispecific AR proteins were synthesized representing the 6G9 linked either at N-terminal to the IL4 binding protein or C-terminal to the IL4 binding protein (SEQ ID NO: 95-100) to examine the effects of the orientation of the AR proteins relative to one another on activity. Each coding nucleic acid sequence was cloned into the expression vector and purified by IMAC chromatography as described above for monospecific AR proteins.
The bispecific AR proteins were evaluated for binding to hIL13 and IL4 as well as the ability to inhibit IL13 and IL4 dependent signaling.
In the HEK-Blue STAT-6 cells, IL13 activates the IL13RA1: IL4R complex (Type 2 receptor) to induce secretion of an embryonic alkaline phosphatase (SEAP) reporter gene via the STAT-6 signaling pathway. An assay for IL13 dependent activation of STAT6 using HEK-Blue STAT-6 cells is commercially available (InVivogen, SanDiego, Calif.). To enable differentiation between high and low affinity binding proteins, an optimal dilution of the crude extract (1:5200) was selected. Stimulation of HEK-Blue STAT-6 cells using crude protein extracts was carried out as follows: on Day 1, cells were plated in 96-well cell culture plates at a density of 2.5×105/ml in 100 uL of cell culture media (DMEM with 4.5 g/L Glucose (11995, Gibco/Invitrogen, Carlsbad, Calif.) with 10% Heat Inactivated FBS (10082, Gibco/Invitrogen, Carlsbad, Calif.), 10 microgm/mL Blasticidin (Invivogen), and 100 microgm per mL Zeocin (Invivogen)) for 24 hours. On Day 2, 100 microL of cell culture media containing the appropriate concentration of AR protein premixed with 1 ng/mL (80 pM) human IL13 (Peprotech) or cyno IL13 was added to the cells. The plates were incubated for 24 hours at 37° C. and 5% CO2. To measure secreted embryonic alkaline phosphatase, 40 microL of each cell supernatant was mixed with 160 microL of Quanti-Blue (Invivogen) in a clear 96-well plate. The plate was incubated for 2 hours at 37° C. and absorbance at 650 nm was read using a plate reader.
All of the bispecific AR proteins retained their ability to bind with high affinity to hIL13 and IL4 (Table 17) irrespective of the orientation of the construct as well as the ability to inhibit IL13 and IL4 dependent signaling (Tables 18 and 19).
In addition to substitutions of the residues at the positions diversified in the creation of libraries based on the formula N-cap-[AR]n—C-cap as well as those mutations described above, generic AR protein mutations may be incorporated. These mutations can be applied to any AR protein molecule, in that these mutations occur within positions of the sequence that are common to all AR proteins as summarized in Table 20 below.
For proteins expressed in E. coli, processing of the N-terminal methionine residue can be affected by the amino acid immediately following the N-terminal methionine (Hirel, et al., Proc Natl Acad Sci USA 86: 8247-51, 1989). Total processing of this methionine residue is desirable to increase the homogeneity of the purified product. In the N-Cap, position 1 was changed from aspartic acid to glycine or alanine in order to determine if the N-terminal methionine residue could be efficiently processed when expressed without the HIS tag. Position 3 of the N-cap is mutated from Gly to Asp, as this mutation has been found to stabilize the AR protein consensus sequence as described in WO2 01/0060748. Position 27 of the AR modules is restricted in diversity to Asn, Tyr, or His in the AR protein library design (Binz et al. Nature Biotech 22:575-582, 2004). As position 28 of the framework is Gly, there is the possibility of isolating AR proteins consisting of the sequence 27Asn-Gly28. The Asn-Gly di-peptide is prone to deamidation reactions (Geiger and Clarke, J Biol Chem 262: 785-94, 1987). As such, position 27 of isolated Asn-Gly sequences can generally be mutated to either Tyr or His. In addition, IL4-binding AR proteins selected by ribosome display end with the amino acid sequence Leu-Asn in the C-cap. This sequence is appended onto the AR proteins in order to accommodate a restriction site for sub-cloning into expression vectors for screening. The preferred amino acid sequence of these positions is Ala-Ala. The C-cap has been further mutated for stability and optimized expression characteristics (SEQ ID NO: 103).
An exemplary, optimized bispecific IL4/IL13 binding protein is that given in SEQ ID NO: 104.
As human and murine IL4 share only 41% sequence identity, it is unlikely that AR proteins selected against human IL4 cross react with mouse IL4. Thus, to enable studies in mouse models where murine IL4 has been demonstrated to play a role in asthma pathologies, it was necessary to select a AR protein that specifically binds to murine IL4 with subnanomolar affinity. Five rounds of ribosome display selection were completed with the N2C and N3C AR protein libraries (Binz, et al., Nat Biotechnol 22: 575-82, 2004) using biotinylated murine IL4 (Peprotech) followed by capture on neutravidin beads. To identify high affinity binders, an off rate selection strategy was performed as follows: biotinylated mIL4 (5 nM) was bound to ribosome displayed AR proteins for either 2 or 6 hours followed by incubation with 2.1 mM unbiotinylated IL4 as a competitor for 4 or 16 hours. AR proteins with a slow off-rate remaining attached to the biotinylated mIL4 were captured on neutravidin particles. An additional round of ribosome display selection was performed under standard conditions to enrich for the high affinity binders. Selected AR proteins were screened using purified AR protein for inhibition of mIL4 dependent HT2 proliferation. HT2 cells, T-lymphocytes isolated from murine spleens (ATCC, CRL-1841™) were cultured using the manufacturer's recommendations (RPMI 1640, 2 mM L-glutamine, 1.5 g/L sodium bicarbonate, 4.5 g/L glucose, 10 mM HEPES, 1.0 mM sodium pyruvate, 0.05 mM 2-mercaptoethanol, 100-200 IU/ml IL-2, and 10% FBS). For the proliferation assay, the cells were removed from the flask and washed 4 times in assay buffer consisting of culture media without IL-2 and plated in 96-well opaque-bottom plates at a density of 5.0×104 cells/ml in 50 μl. Cells were treated with 74 pM IL4 and appropriate concentrations of AR protein and incubated at 37° C., 5% CO2 for 48 hours. Cell Titer Glo (Promega G7571) was added to the assay plate (100 μL), covered and placed on a shaker for 40 minutes at room temperature. Luminescence was measured from a top read using the SpectraMax M5 plate reader (Molecular Devices, Sunnyvale, Calif.). Based on affinity for mIL4, neutralization of mIL4 binding to IL4R, neutralization of mIL4 dependent HT2 proliferation, thermal stability and monodispersity by size exclusion chromatography, AR protein C06—21H2 (SEQ ID NO: 105) was chosen as the surrogate mIL4 binding AR protein for in vivo work.
Bispecific Activity
In order to test the effects of simultaneous inhibition of both IL4 and IL13 inhibition in murine models of asthma, a bispecific AR protein linking C06—21H2 and C02—11G11 (SEQ ID NO: 106), a potent murine IL13 inhibitor was engineered to link the N-terminus of C06—21H2 to the C-terminus of C02—11G11 via a (GGGGS)4 polypeptide linker. An N-terminal histidine tag was appended to the N-terminus in order to aide purification, as described above.
In order to evaluate the potential to deliver a AR protein via nebulization using a rodent inhalation system, nebulization stability studies were performed with the surrogate bispecific AR protein (11G11-21H2). Aerosols were generated with a Pari LC Plus jet nebulizer connected to compressed air with an inlet pressure of 20 psi. This resulted in an output flow of ˜5 L/min. Solution formulations of 11G1-21H2 were prepared at 20 mg/mL in PBS. Aerosols were directed through approximately 24 in. of a 1.58-cm (diameter) delivery line. The delivery line was fitted with forced air dilution flow of approximately 10 L/min. Aerosols transited into a flow-past 24-port nose-only rodent exposure chamber. The chamber exhaust flow rate was adjusted to a volumetric flow rate of approximately 20 L/min, resulting in the chamber being slightly negative to ambient conditions. Aerosols were collected on 47-mm Zefluor filters at a nominal volumetric flow rate of 1.0 L/min. Samples recovered from filters were analyzed by SEC and absorbance at 280 nm to assess potential aggregates and AR protein concentration.
Particle size distribution was measured by a Mercer-style, seven-stage cascade impactor (IN-TOX Products, Inc., Albuquerque, N. Mex.). Impactor samples were collected for between 1 and 2 min, as aerosol concentration required, at a nominal flow rate of 2 L/min. Impactor data were analyzed to determine the mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD). In order to extract the samples from the filters they were rolled and placed in glass vials. Four milliliters of PBS was added to each vial. The vials were sealed and placed on a rotator for 45 minutes at 40 rpm. Samples were transferred into HPLC vials for analysis. The samples were then analyzed by size exclusion chromatography (SEC). The analysis showed that nebulized AR protein 11G11-21H2, collected as condensed aerosol at 30 minutes and 1 hour, the main peaks eluted at 6.09 minute. In the sample of 11G11-21H2 remaining in the sample cup post nebulization; the main peak eluted at 5.9 minutes. The sample increase in sample concentration with longer nebulization times was evidenced by an increase in peak intensity.
The samples were also tested for activity in the IL13 and IL4 dependent Stat6 and IL4 dependent HT2 proliferation assay respectively as previously described. Prior to testing, the concentration of aerosolized AR protein or AR protein retained in the cup were assessed by A280 and the activity was measured using the IL13 STAT6 activation assay (
The pharmacokinetic profile of 11G11-21H2 was determined for protein delivered via intratracheal instillation at 4 mg/kg, in healthy or mice sensitized and challenged with ovalbumin to mimic the asthmatic lung. Animals were anesthetized with 3-5% isoflurane until they failed to respond to toe pinch and did not respond to having the catheter inserted into the trachea. A 20 gauge catheter or smaller was inserted into the trachea and the compound instilled into the lungs in a smooth motion. The volume of solution inserted during a single instillation was approximately 50 μl. Data were collected at multiple times points with n=5 mice/time point. The concentration of the 11G11-21H2 construct was determined from bronchoaveolar lavage (BAL), lung homogenate and serum samples by ELISA using AR protein specific antibodies (
For comparison, due to their small size, AR proteins that are dosed systemically by intravenous injection clear from circulation with a half-life of less than 30 minutes (data not shown).
In order to evaluate the ability of 11G11-21H2 to inhibit both IL4 and IL13 dependent outcomes in vivo, the murine acute OVA sensitization and challenge model was used. Briefly, 8-10 wk old female BALB/c mice were immunized with an intraperitoneal injection of a mixture of ovalbumin (OVA, 10 microgram) and aluminum hydroxide (Alum, 2 mg) in sterile water on day 0 and 7. Mice were then challenged intranasally with ovalbumin for 2 days starting on day 14 and sacrificed for analysis on day 16. For the non-sensitized group, mice were immunized with sterile water only and treated with PBS by inhalation (vehicle control). For all other groups, mice were sensitized with OVA and treated with 11G11 (anti-IL13 AR protein), 21H2 (anti-IL4 AR protein), 1G11-21H2 (anti-IL4; anti-IL13 bispecific AR protein) or E3—5 (a non-binding control AR protein) at 20 mg/kg (monospecifics) or 40 mg/kg (bispecific). 11G11-21H2 or E3—5 was delivered via intratracheal instillation 1× per day beginning the day before OVA challenge and up to the day before sacrifice (day 13-16). Forty eight hours following the last OVA challenge, mice were anesthetized and their pulmonary function (response to methacholine challenge) tested by whole body plethysmography (Buxco) and then immediately sacrificed. BAL (1 mL PBS) was performed post mortem to collect cells and fluid from all animals, cell number and differentials were calculated and BAL supernatant was frozen at −80° C.
As shown in
The crystal structure of the complex between IL13 binding protein 6G9 (SEQ ID NOS: 162 formed from ARs in SEQ ID NOS: 109, 127 and 144) and found in bi-specific IL4/IL13 binding protein (SEQ ID NOS: 41, 104 and 177) and cyno IL13 was determined at 1.6 Å resolution. The conformational epitope has been identified, as well as the binding protein residues involved in target recognition.
The following abbreviations are used: HEPES: N-(2-hydroxyethyl)-piperazine-N′-2-ethanesulfonic acid; MES: 2-(N-morpholino)ethanesulfonic acid; PBS: phosphate buffered saline; PEG: polyethylene glycol; RMSD: root-mean-square deviation; SEC: size exclusion chromatography; binding protein 6G9 was developed to bind IL13 with high affinity and block signaling through its receptor IL13Rα1/IL4Rα.
6G9 binds human IL13 with a KD in the picomolar range and exhibits cross-reactivity towards cyno IL13. For insight into the mechanism of action, binding protein 6G9 was crystallized in complex with cyno IL13. The structure was determined at 1.6 Å resolution.
Proteins
Cyno IL13 with the N-terminal SUMO tag was expressed in E. coli and purified by HisTrap, SUMO tag cleavage, and SEC in a final PBS buffer, pH 7.2; Lot No. 081126-CP00721y.
Complex Preparation
Binding protein 6G9 was further purified on a MonoQ HR 5/5 column (GE Healthcare) equilibrated with 20 mM MES, pH 6.5 (buffer A). Elution was performed with an 11-29% gradient of 20 mM MES, pH 6.5, 1 M NaCl (buffer B) in 40 column volumes. The main peak fractions were concentrated and used for complex formation.
Binding protein:IL13 complex was prepared by mixing 6G9 with excess IL13 at a molar ratio of 1:1.1 and incubated for 2 hours at 4° C. SEC on a Superdex 200 column separated the unbound species. The complex was concentrated using an Amicon-Ultra 5 kDa device to 13.75 mg/mL in 20 mM HEPES pH 7.5, 100 mM NaCl.
Crystallization
Crystallization of the complex was carried out by the vapor-diffusion method at 20° C. using an Oryx4 robot (Douglas Instruments). The experiments were composed of equal volumes of protein and reservoir solution in a sitting drop format in 96-well Corning 3550 plates. The initial screening was performed with the PEGs suite (Qiagen) and in-house screens IH1 and IH2, and protein complex solution at 13.75 mg/mL. Plate-shaped stacked crystals appeared from IH2 conditions A1-A4 with 0.1 M Na acetate buffer, pH 4.5, 18-25% PEG 3350, and either 0.2 M lithium sulfate or 0.2 M ammonium sulfate. These crystals were used to prepare seeds for microseed matrix screening in a stabilizing solution of 0.1 M Na acetate buffer, pH 4.5, 25% PEG 3350, and 0.2 M lithium sulfate. Seeding was performed using 0.2 μL protein, 0.05 μL seeds, and 0.15 μL reservoir. Diluted protein complex (4.8 mg/mL) and 50-fold diluted seeds were used for optimization of conditions. X-ray quality crystals were obtained from 0.1 M Na acetate, pH 4.5, 11% PEG 3350, 0.2 M Li2SO4. The crystal data are given in Table 21.
X-Ray Data Collection and Structure Determination
For X-ray data collection, one crystal was soaked for a few seconds in a cryo-protectant solution containing 0.1 M Na acetate, pH 4.5, 20% PEG 3350, 0.2 M LiCl, 20% glycerol and was frozen in liquid nitrogen. Diffraction data were collected at the Swiss Light Source synchrotron over a 180° crystal rotation with 0.25-sec exposures per 0.25°-image and were processed with the program XDS. X-ray data statistics are given in Table 21.
The structure was solved by molecular replacement. The crystal structures of binding protein 6G9 (DAR6G9XP01) and human IL-13 (I130062G02) were used as search models. All crystallographic calculations were performed with the CCP4 suite of programs. Model adjustments were carried out using the program COOT. The refinement statistics are given in Table 21.
Binding Protein/IL13 Interface
The crystal structure of the complex is shown in
Comparison of the binding protein structures in complex with IL13 and alone indicates that the binding protein molecule is relatively rigid. Upon binding the target (IL13), binding protein opens by ˜3.5° as shown in
Intermolecular interactions at the ridge are mostly hydrophobic (
Interactions at the groove of binding protein involve both hydrophobic and charged residues (
Three residues at the end of helix D seem to contribute a good portion of the binding energy: F107, R108 and N113 (each are 1 amino acid different in position than in SEQ ID NO: 101 for which it is F106, R107 and N112). The latter provides the C-terminal carboxyl group, which forms 3 salt bridges, to R23 (two) and R56 (
The neutralization effect of 6G9 is due to blocking the IL13 interaction with the receptor chain IL13Rα1. 6G9 does not interfere with IL4Rα as can be judged from the crystal structure of IL13: IL13Rα1: IL4Rα complex.
Electrostatic Interactions
Although charged residues play a significant role in the interactions, their distribution is quite unexpected. The binding surface of IL13 formed by helices A and D is positively charged due to a number of basic residues. The groove of binding protein, however, also bears a positive charge in the left (N-terminal) half, i.e. exactly where it binds IL13. Somehow, the positive charge of the central cluster (R23, R56, R90) is balanced by the IL13 C-terminal charge and the dipole of helix D. The acidic patch in the groove that includes D77, D81, D110, E114, D143, D151 and D155, does not contribute much to the interactions.
Cross Reactivity
Human and cyno IL13 differ in only 6 positions (
Also, the R/Q substitution in position 111 should not affect binding. Curiously, residue 111 is the only residue in the C-terminal portion of helix D that is not involved in the interactions (
IL13 Structure
The IL13 structure is available for comparisons from the antibody complexes determined previously. All these antibodies bind IL13 at the surface formed by helices A and D. Superposition of the structures show that the arrangement of helices in the 4-helical bundle is essentially the same in all structures (
In contrast to the helical core, loops AB and CD connecting the helices exhibit substantial variability. In the present structure, loop CD is completely disordered. Given their flexibility, the observed conformations of the loops are most likely affected by crystal packing since the loops are not involved in contacts with antibodies.
The crystal structure of the IL13:Binding protein 6G9 complex has revealed that this binding protein recognizes helices A and D of IL13. The epitope is virtually the same as that of one of the IL13 antibodies. The C-terminal carboxyl group of N113 is a key element of the epitope. Target recognition involves all 4 β-turns and 4 out of 5 helices forming the groove. R23 from the N-terminal cap is an essential recognition residue. Binding protein-IL13 interactions at the ridge formed by β-turns are predominantly hydrophobic. Interactions at the groove are both hydrophobic and electrostatic. Upon binding IL13, the binding protein molecule opens by ˜3.5°.
Sequence alignment indicates that the binding protein epitope identified here for cyno IL13 is preserved in wt human IL13 and R111Q (aka R130Q) human variant. Therefore, binding protein 6G9 is expected to be cross-reactive towards these species. The neutralization effect of binding protein 6G9 is due to blocking the IL13 interaction with the receptor chain IL13Rα1. 6G9 does not interfere with IL4Rα. The acetate ion bound to R108 of IL13 is located at the binding protein-IL13 interface. This suggests that not only acetate but possibly other anions, e.g. phosphate, may have a negative impact on binding by the binding protein.
Sequence Tables
sapiens
IL13 Binding Protein AR Sequences
XDXXGXTPLH LAAXXGHLEI VEVLLKXGAD VNA
XDXXGXTPLH LAAXXGHLEI VEVLLKXGAX VNA
This application claims the benefit of U.S. Provisional Application Ser. No. 61/480,999, filed 29 Apr. 2011, U.S. Provisional Application Ser. No. 61/481,008, filed 29 Apr. 2011, and U.S. Provisional Application Ser. No. 61/481,021 filed 29 Apr. 2011, the entire contents of which are incorporated herein by reference in their entireties.
| Number | Name | Date | Kind |
|---|---|---|---|
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| 7875465 | Shiotsuka et al. | Jan 2011 | B2 |
| 20090082274 | Stumpp et al. | Mar 2009 | A1 |
| 20110262964 | Bedouelle et al. | Oct 2011 | A1 |
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| WO 9002809 | Mar 1990 | WO |
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| WO 0220565 | Mar 2002 | WO |
| WO 2007006665 | Jan 2007 | WO |
| WO 2009138413 | Nov 2009 | WO |
| WO 2010060748 | Jun 2010 | WO |
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| Number | Date | Country | |
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| 20120277143 A1 | Nov 2012 | US |
| Number | Date | Country | |
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| 61480999 | Apr 2011 | US | |
| 61481008 | Apr 2011 | US | |
| 61481021 | Apr 2011 | US |
