Patent Application
20200102575
AAT, (SERPINA1), a 52 kDa a serum serine protease inhibitor, functions to protect the lung from the powerful protease neutrophil elastase (NE)4-10. AAT also inhibits the activity of other neutrophil-released proteases, including proteinase 3, α-defensins and cathepsin G and has anti-inflammatory and immunomodulatory properties48-88. Serum deficiency of AAT is associated with an imbalance between proteases and AAT in the lung, leading to slow destruction of the lung parenchyma, a process accelerated by cigarette smoking4,5,7,8,11,12,59-61. The consequence is the development of early-onset of panacinar emphysema at ages 35 to 40 in smokers and age 55 to 60 in nonsmokers, with a reduced life span of approximately 15 to 20 yr4,57,32-64 The disorder affects 70,000 to 100,000 individuals in the USA82,88. AAT deficiency is also associated with childhood and adult liver cirrhosis, and rarely with hepatocellular carcinoma, panniculitis and vasculitis and autoimmune disorders66-73. AAT is mainly produced in the liver reaching the lung by diffusion from the circulation4,5,7,8,10-12,63,74 with a small percentage secreted from mononuclear phagocytes78,78, neutrophils77, bronchial epithelial cells78,79, and small intestine epithelial cells80,81. AAT in plasma diffuses into the lung, where it protects the fragile alveolar structures from proteases carried by neutrophils generated in bone marrow. The lung is the organ most susceptible to neutrophil elastase mediated proteolytic destruction (
Low circulating levels of AAT are the result of mutations in the SERPINA1 gene (MIM 107400)82,83, with more than 120 naturally occurring alleles88,84-88. The normal AAT alleles are M1(Ala213), M1(Val213), M2, M2 and M487. The most common deficient variants are the severe Z allele, observed with high frequency in Caucasians in Northern European countries and North America, and the milder S form, with high prevalence in the Iberian Peninsula65,70,88. The vast majority of cases of emphysema associated with AAT deficiency are caused by homozygous inheritance of the severe Z variant, with a single amino acid substitution of lysine for glutamic acid at position 342 (E342K)88. The Z mutation causes the AAT protein to polymerize in hepatocytes, preventing secretion into the blood83,88,70,88-92. The S allele, a single amino acid substitution of a glutamic acid by a valine at position 264 (E264V), results in an unstable protein with reduced serum half-life93-98. Individuals homozygous for the Z mutation (ZZ) have plasma AAT levels 10 to 15% of the normal M allele and account for approximately >95% of cases of clinically recognized AAT deficiency5,7,10,11,65,71,97.
Gene therapy vectors comprising an expression cassette coding for an oxidation-resistant alpha 1-antitrypsin (AAT) are provided. The oxidation-resistant alpha 1-antitrypsin nucleic acid may comprise one or mutations encoding one or more substitution(s), e.g., those described in Table 1, and the resulting AAT protein (a variant relative to the parental AAT sequence) is oxidation-resistant compared to an AAT sequence that does not have the one or more substitutions (e.g., the parental AAT nucleic acid sequence made encode an oxidation-sensitive AAT sequence, such as a M1(Ala213) sequence). Thus, in one embodiment, the base expression cassette that encodes an oxidation-sensitive AAT that is then made oxidation-resistant, may be the M1(Ala213) variant. In another embodiment, the base expression cassette that encodes an oxidation-sensitive AAT that is then made oxidation-resistant may be the M1(Val213) variant. Also provided are methods to treat alpha 1-antitrypsin deficiency comprising administering to a subject in need thereof, a pharmaceutical composition comprising one or more vectors described herein. In one embodiment, the vector may be delivered to the pleura. In one embodiment, the vector may be intravenously delivered
Advantages of gene therapy include that 1) a single administration may permanently compensate for the genetic abnormality, obviating the requirement of weekly or monthly parenteral infusions of AAT, 2) a steady state of AAT occurs over time, 3) there is a lack of risk of viral contamination from pooled plasma, and 4) there may be a lower cost.
In one embodiment, a viral or plasmid gene therapy vector is provided comprising an expression cassette coding for an oxidation-resistant alpha 1-antitrypsin that has an oxidation-resistant amino acid at, for example, position 351, position 358, or both positions 351 and 358. In one embodiment, the oxidation-resistant amino acid is leucine, valine, glycine, isoleucine, alanine, threonine, asparagine, serine, or aspartic acid. In one embodiment, the oxidation-resistant amino acid is leucine, valine, glycine, isoleucine, or alanine. In one embodiment, position 358 in alpha 1-antitrypsin has an oxidation-resistant amino acid. In one embodiment, position 351 has an oxidation-resistant amino acid. In one embodiment, position 358 has an oxidation-resistant amino acid. In one embodiment, position 351 and position 358 each has an oxidation-resistant amino acid. In one embodiment, the oxidation-resistant residue is leucine or valine. In one embodiment, the alpha 1-antitrypsin has an alanine at position 213. In one embodiment, the alpha 1-antitrypsin sequence other than the residue at position 351 and/or 358 is the M1(Ala213) variant sequence. In one embodiment, the alpha 1-antitrypsin has a valine at position 213. In one embodiment, the alpha 1-antitrypsin sequence other than the residue at positions 351 and/or 358 is the M1 (Val213) variant sequence. In one embodiment, the vector is a viral gene therapy vector, e.g., an adenovirus, adeno-associated virus (AAV), retrovirus or lentivirus vector. In one embodiment, the AAV vector is pseudotyped. In one embodiment, the AAV vector is pseudotyped with AAVrh. 10, AAV8, AAV9, AAV5, AAVhu.37, AAVhu.20, AAVhu.43, AAVhu.8, AAVhu.2, or AAV7 capsid. In one embodiment, the AAV vector is pseudotyped with AAVrh.10, AAV8, or AAV5. In one embodiment, the AAV vector is AAV2, AAV5, AAV7, AAV8, AAV9 or AAVrh.10. Further provided is a pharmaceutical composition comprising an amount of the gene therapy vector described above. A dose of the viral vector may be about 1×1011 to about 1×1016 genome copies, about 1×1012 to about 1×1015 genome copies about 1×1011 to about 1×1013 genome copies, or about 1×1013 to about 1×1015 genome copies.
The vector or pharmaceutical composition may be employed to prevent, inhibit or treat alpha 1-antitrypsin deficiency. For example, an effective amount of the vector or the pharmaceutical composition may be administered to a subject in need thereof. In one embodiment, the composition is delivered to the pleura. In one embodiment, the composition is intravenously administered. In one embodiment, the subject is a human. In one embodiment, the human has emphysema.
The vector or pharmaceutical composition may also be employed to prevent, inhibit or treat emphysema, COPD, respiratory distress syndrome or fibrotic interstitial lung disease in a mammal by administering to a mammal in need thereof, an effective amount of the vector or the pharmaceutical composition. In one embodiment, the composition is delivered to the pleura. In one embodiment, the composition is intravenously administered. In one embodiment, the mammal is a human. In one embodiment, the human has emphysema.
The vector or pharmaceutical composition may further be employed to prevent, inhibit or treat oxidative damage to the lung, e.g., by administering to a subject in need thereof an effective amount of a composition comprising the vector or the pharmaceutical composition. In one embodiment, the composition is delivered to the pleura. In one embodiment, the composition is intravenously administered. In one embodiment, the subject is a human.
In the following description, reference is made to the accompanying drawings that form a part hereof, and in which is shown byway of illustration specific embodiments which may be practiced. These embodiments are described in detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical changes may be made without departing from the scope of the present invention. The following description of example embodiments is, therefore, not to be taken in a limited sense, and the scope of the present invention is defined by the appended claims.
The Abstract is provided to comply with 37 C.F.R. § 1.72(b) to allow the reader to quickly ascertain the nature and gist of the technical disclosure. The Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.
A “vector” refers to a macromolecule or association of macromolecules that comprises or associates with a polynucleotide, and which can be used to mediate delivery of the polynucleotide to a cell, either in vitro or in vivo. Illustrative vectors include, for example, plasmids, viral vectors, liposomes and other gene delivery vehicles. The polynucleotide to be delivered; sometimes referred to as a “target polynucleotide” or “transgene,” may comprise a coding sequence of interest in gene therapy (such as a gene encoding a protein of therapeutic interest), a coding sequence of interest in vaccine development (such as a polynucleotide expressing a protein, polypeptide or peptide suitable for eliciting an immune response in a mammal), and/or a selectable or detectable marker.
“Transduction,” “transfection,” “transformation” or “transducing” as used herein, are terms referring to a process for the introduction of an exogenous polynucleotide into a host cell leading to expression of the polynucleotide, e.g., the transgene in the cell, and includes the use of recombinant virus to introduce the exogenous polynucleotide to the host cell. Transduction, transfection or transformation of a polynucleotide in a cell may be determined by methods well know n to the art including, but not limited to, protein expression (including steady state levels), e.g.; by ELISA, flow cytometry and Western blot, measurement of DNA and RNA by hybridization assays, e.g., Northern blots, Southern blots and gel shift mobility assays. Methods used for the introduction of the exogenous polynucleotide include well-know n techniques such as viral infection or transfection, lipofection, transformation and electroporation, as well as other non-viral gene delivery techniques. The introduced polynucleotide may be stably or transiently maintained in the host cell.
“Gene delivery” refers to the introduction of an exogenous polynucleotide into a cell for gene transfer, and may encompass targeting, binding, uptake, transport, localization, replicon integration and expression.
“Gene transfer” refers to the introduction of an exogenous polynucleotide into a cell which may encompass targeting, binding, uptake, transport, localization and replicon integration, but is distinct from and does not imply subsequent expression of the gene.
“Gene expression” or “expression” refers to the process of gene transcription, translation, and post-translational modification.
An “infectious” virus or viral particle is one that comprises a polynucleotide component which it is capable of delivering into a cell for which the viral species is trophic. The term does not necessarily imply any replication capacity of the virus.
The term “polynucleotide” refers to a polymeric form of nucleotides of any length, including deoxyribonucleotides or ribonucleotides, or analogs thereof. A polynucleotide may comprise modified nucleotides, such as methylated or capped nucleotides and nucleotide analogs, and may be interrupted by non-nucleotide components. If present, modifications to the nucleotide structure may be imparted before or after assembly of the polymer. The term polynucleotide, as used herein, refers interchangeably to double- and single-stranded molecules. Unless otherwise specified or required, any embodiment of the invention described herein that is a polynucleotide encompasses both the double-stranded form and each of two complementary single-stranded forms know nor predicted to make up the double-stranded form.
An “isolated” polynucleotide, e.g., plasmid, virus, polypeptide or other substance refers to a preparation of the substance devoid of at least some of the other components that may also be present where the substance or a similar substance naturally occurs or is initially prepared from. Thus, for example, an isolated substance may be prepared by using a purification technique to enrich it from a source mixture. Isolated nucleic acid, peptide or polypeptide is present in a form or setting that is different from that in which it is found in nature. For example, a given DNA sequence (e.g., a gene) is found on the host cell chromosome in proximity to neighboring genes; RNA sequences, such as a specific mRNA sequence encoding a specific protein, are found in the cell as a mixture with numerous other mRNAs that encode a multitude of proteins. The isolated nucleic acid molecule may be present in single-stranded or double-stranded form. When an isolated nucleic acid molecule is to be utilized to express a protein, the molecule will contain at a minimum the sense or coding strand (i.e., the molecule may single-stranded), but may contain both the sense and anti-sense strands (i.e., the molecule may be double-stranded), Enrichment can be measured on an absolute basis, such as weight per volume of solution, or it can be measured in relation to a second, potentially interfering substance present in the source mixture. Increasing enrichments of the embodiments of this invention are increasingly preferred. Thus, for example, a 2-fold enrichment, 10-fold enrichment, 100-fold enrichment, or a 1000-fold enrichment.
A “transcriptional regulatory sequence” refers to a genomic region that controls the transcription of a gene or coding sequence to which it is operably linked. Transcriptional regulatory sequences of use in the present invention generally include at least one transcriptional promoter and may also include one or more enhancers and/or terminators of transcription.
“Operably linked” refers to an arrangement of two or more components, wherein the components so described are in a relationship permitting them to function in a coordinated manner. By way of illustration, a transcriptional regulatory sequence or a promoter is operably linked to a coding sequence if the TRS or promoter promotes transcription of the coding sequence. An operably linked TRS is generally joined in cis with the coding sequence, but it is not necessarily directly adjacent to it.
“Heterologous” means derived from a genotypically distinct entity from the entity to which it is compared. For example, a polynucleotide introduced by genetic engineering techniques into a different cell type is a heterologous polynucleotide (and, when expressed, can encode a heterologous polypeptide). Similarly, a transcriptional regulatory element such as a promoter that is removed from its native coding sequence and operably linked to a different coding sequence is a heterologous transcriptional regulatory element.
A “terminator” refers to a polynucleotide sequence that tends to diminish or prevent read-through transcription (i.e., it diminishes or prevent transcription originating on one side of the terminator from continuing through to the other side of the terminator). The degree to which transcription is disrupted is typically a function of the base sequence and/or the length of the terminator sequence. In particular; as is well known in numerous molecular biological systems, particular DNA sequences, generally referred to as “transcriptional termination sequences” are specific sequences that tend to disrupt read-through transcription by RNA polymerase, presumably by causing the RNA polymerase molecule to stop and/or disengage from the DNA being transcribed. Typical example of such sequence-specific terminators include polyadenylation (“polyA”) sequences, e.g., SV40 polyA. In addition to or in place of such sequence-specific terminators, insertions of relatively long DNA sequences between a promoter and a coding region also tend to disrupt transcription of the coding region, generally in proportion to the length of the intervening sequence. This effect presumably arises because there is always some tendency for an RNA polymerase molecule to become disengaged from the DNA being transcribed, and increasing the length of the sequence to be traversed before reaching the coding region would generally increase the likelihood that disengagement would occur before transcription of the coding region was completed or possibly even initiated. Terminators may thus prevent transcription from only one direction (“uni-directional” terminators) or from both directions (“bi-directional” terminators), and may be comprised of sequence-specifics termination sequences or sequence-non-specific terminators or both. A variety of such terminator sequences are known in the art; and illustrative uses of such sequences within the context of the present invention are provided below.
“Host cells,” “cell lines,” “cell cultures,” “packaging cell line” and other such terms denote higher eukaryotic cells, such as mammalian cells including human cells, useful in the present invention; e.g.; to produce recombinant virus or recombinant fusion polypeptide. These cells include the progeny of the original cell that was transduced. It is understood that the progeny of a single cell may not necessarily be completely identical (in morphology or in genomic complement) to the original parent cell.
“Recombinant,” as applied to a polynucleotide means that the polynucleotide is the product of various combinations of cloning, restriction and/or ligation steps, and other procedures that result in a construct that is distinct from a polynucleotide found in nature. A recombinant virus is a viral particle comprising a recombinant polynucleotide. The terms respectively include replicates of the original polynucleotide construct and progeny of the original virus construct.
A “control element” or “control sequence” is a nucleotide sequence involved in an interaction of molecules that contributes to the functional regulation of a polynucleotide, including replication, duplication, transcription, splicing, translation, or degradation of the polynucleotide. The regulation may affect the frequency, speed, or specificity of the process, and may be enhancing or inhibitory in nature. Control elements know n in the art include, for example, transcriptional regulatory sequences such as promoters and enhancers. A promoter is a DNA region capable under certain conditions of binding RNA polymerase and initiating transcription of a coding region usually located downstream (in the 3′ direction) from the promoter. Promoters include AAV promoters, e.g., P5, P19, P40 and AAV ITR promoters, as w ell as heterologous promoters.
An “expression vector” is a vector comprising a region which encodes a gene product of interest, and is used for effecting the expression of the gene product in an intended target cell. An expression vector also comprises control elements operatively linked to the encoding region to facilitate expression of the protein in the target. The combination of control elements and a gene or genes to which they are operably linked for expression is sometimes referred to as an “expression cassette,” a large number of which are know n and available in the art or can be readily constructed from components that are available in the art.
The terms “polypeptide” and “protein” are used interchangeably herein to refer to polymers of amino acids of any length. The terms also encompass an amino acid polymer that has been modified; for example, disulfide bond formation, glycosylation, acetylation, phosphorylation, lipidation, or conjugation with a labeling component.
The term “exogenous,” when used in relation to a protein, gene, nucleic acid, or polynucleotide in a cell or organism refers to a protein, gene, nucleic acid, or polynucleotide which has been introduced into the cell or organism by artificial or natural means. An exogenous nucleic acid may be from a different organism or cell, or it may be one or more additional copies of a nucleic acid which occurs naturally within the organism or cell. By way of a non-limiting example, an exogenous nucleic acid is in a chromosomal location different from that of natural cells, or is otherwise flanked by a different nucleic acid sequence than that found in nature, e.g., an expression cassette which links a promoter from one gene to an open reading frame for a gene product from a different gene.
“Transformed” or “transgenic” is used herein to include any host cell or cell line, which has been altered or augmented by the presence of at least one recombinant DNA sequence. The host cells of the present invention are typically produced by transfection with a DNA sequence in a plasmid expression vector, as an isolated linear DNA sequence, or infection with a recombinant viral vector.
The term “sequence homology” means the proportion of base matches between two nucleic acid sequences or the proportion amino acid matches between two amino acid sequences. When sequence homology is expressed as a percentage, e.g., 50%, the percentage denotes the proportion of matches over the length of a selected sequence that is compared to some other sequence. Gaps (in either of the two sequences) are permitted to maximize matching; gap lengths of 15 bases or less are usually used, 6 bases or less are preferred with 2 bases or less more preferred. When using oligonucleotides as probes or treatments, the sequence homology between the target nucleic acid and the oligonucleotide sequence is generally not less than 17 target base matches out of 20 possible oligonucleotide base pair matches (85%); not less than 9 matches out of 10 possible base pair matches (90%), or not less than 19 matches out of 20 possible base pair matches (95%).
Two amino acid sequences are homologous if there is a partial or complete identity between their sequences. For example, 85% homology means that 85% of the amino acids are identical when the two sequences are aligned for maximum matching. Gaps (in either of the two sequences being matched) are allowed in maximizing matching; gap lengths of 5 or less are preferred with 2 or less being more preferred. Alternatively and preferably; two protein sequences (or polypeptide sequences derived from them of at least 30 amino acids in length) are homologous, as this term is used herein, if they have an alignment score of at more than 5 (in standard deviation units) using the program ALIGN with the mutation data matrix and a gap penalty of 6 or greater. The two sequences or parts thereof are more homologous if their amino acids are greater than or equal to 50% identical when optimally aligned using the ALIGN program.
The term “corresponds to” is used herein to mean that a polynucleotide sequence is structurally related to all or a portion of a reference polynucleotide sequence, or that a polypeptide sequence is structurally related to all or a portion of a reference polypeptide sequence, e.g., they have at least 80%, 85%, 90%, 95% or more, e.g.; 99% or 100%, sequence identity. In contradistinction, the term “complementary to” is used herein to mean that the complementary sequence is homologous to all or a portion of a reference polynucleotide sequence. For illustration, the nucleotide sequence “TATAC” corresponds to a reference sequence “TATAC” and is complementary to a reference sequence “GTATA”.
The term “sequence identity” means that two polynucleotide sequences are identical (i.e., on a nucleotide-by-nucleotide basis) over the window of comparison. The term “percentage of sequence identity” means that two polynucleotide sequences are identical (i.e., on a nucleotide-by-nucleotide basis) over the window of comparison. The term “percentage of sequence identity” is calculated by comparing two optimally aligned sequences over the window of comparison, determining the number of positions at which the identical nucleic acid base (e.g., A, T, C, G, U, or I) occurs in both sequences to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the window of comparison (i.e., the window size); and multiplying the result by 100 to yield the percentage of sequence identity. The terms “substantial identity” as used herein denote a characteristic of a polynucleotide sequence, wherein the polynucleotide comprises a sequence that has at least 85 percent sequence identity, preferably at least 90 to 95 percent sequence identity, more usually at least 99 percent sequence identity as compared to a reference sequence over a comparison window of at least 20 nucleotide positions, frequently over a window of at least 20-50 nucleotides, wherein the percentage of sequence identity is calculated by comparing the reference sequence to the polynucleotide sequence which may include deletions or additions which total 20 percent or less of the reference sequence over the window of comparison.
“Conservative” amino acid substitutions are, for example, aspartic-glutamic as polar acidic amino acids; lysine/arginine/histidine as polar basic amino acids; leucine/isoleucine/methionine/valine/alanine/glycine/proline as non-polar or hydrophobic amino acids; serine/threonine as polar or uncharged hydrophilic amino acids. Conservative amino acid substitution also includes groupings based on side chains. For example, a group of amino acids having aliphatic side chains is glycine; alanine, valine, leucine, and isoleucine; a group of amino acids having aliphatic-hydroxyl side chains is serine and threonine; a group of amino acids having amide-containing side chains is asparagine and glutamine; a group of amino acids having aromatic side chains is phenylalanine, tyrosine, and tryptophan; a group of amino acids having basic side chains is lysine; arginine, and histidine; and a group of amino acids having sulfur-containing side chains is cysteine and methionine. For example, it is reasonable to expect that replacement of a leucine with an isoleucine or valine, an aspartate with a glutamate; a threonine with a serine, or a similar replacement of an amino acid with a structurally related amino acid will not have a major effect on the properties of the resulting polypeptide. Whether an amino acid change results in a functional polypeptide can readily be determined by assaying the specific activity of the polypeptide. Naturally occurring residues are divided into groups based on common side-chain properties: (1) hydrophobic: norleucine, met, ala; val, leu, ile; (2) neutral hydrophilic: cys, ser, thr; (3) acidic; asp, glu; (4) basic; asn, gin, his, lys, arg; (5) residues that influence chain orientation: gly, pro; and (6) aromatic; trp, tyr, phe. The invention also envisions polypeptides with non-conservative substitutions. Non-conservative substitutions entail exchanging a member of one of the classes described above for another.
Nucleic Acid Sequence which Encodes an AAT
AAT, (SERPINA 1), a 52 kDa a serum serine protease inhibitor; functions to protect the lung from the powerful protease neutrophil elastase (NE)4-10 Low circulating levels of AAT are the result of mutations in the SERPINA 1 gene (MIM 107400)82,83; with more than 120 naturally occurring alleles65,84-86. The normal AAT alleles are M1 (Ala213), M1(Val213), M2, M2 and me. The most common deficient variants are the severe Z allele, observed with high frequency in Caucasians in Northern European countries and North America, and the milder S form, with high prevalence in the Iberian Peninsula65,70,85. AAT deficiency is a common, fatal autosomal recessive disorder characterized by low (<11 μM) plasma levels of AAT. Generally; is it associated with the development of panacinar emphysema, manifesting clinically in smokers ages 35-45 and in non-smokers 55-65. Current therapy is weekly or monthly intravenous administration of AAT purified pooled plasma.
The vast majority of cases of emphysema associated with AAT deficiency are caused by homozygous inheritance of the severe Z variant; with a single amino acid substitution of lysine for glutamic acid at position 342 (E3421c)88. The Z mutation causes the AAT protein to polymerize in hepatocytes, preventing secretion into the blood63,65,70,88-92. The S allele, a single amino acid substitution of a glutamic acid by a valine at position 264 (E264V), results in an unstable protein with reduced serum half-life93-96. Individuals homozygous for the Z mutation (ZZ) have plasma AAT levels 10 to 15% of the normal M allele and account for approximately >95% of cases of clinically recognized AAT deficiency5,7,10,11,65,71,97.
An exemplary adeno-associated virus, e.g., serotype 8 adeno-associated virus, was prepared for coding for a next generation oxidation-resistant AAT in vivo gene therapy strategy to treat the pulmonary manifestations of AAT deficiency. Throughout this specification which includes its figures, an embodiment is at times referenced as AAV.vAAT.
A significant advantage of the compositions provided herein is that they provide an oxidation-resistant form of AAT that provides a more stable, effective therapy, despite the persistent stress of the AAT in the lung by inhaled oxidants; common in everyday life101,102 this regard, compositions described herein have the marked advantage in that, for the amount of AAT available to defend the lower respiratory tract, AAV.vAAT is far more likely to make available functional AAT molecules to defend the alveolar structures from NE, requiring less gene therapy-generated AAT to be effective.
The parameters relevant to designing the composition include: (1) the viral vector or capsid; (2) the expression cassette including the promoter and AAT coding sequence; and (3) route of administration.
Capsid.
AAV is highly effective in transducing organs in vivo, with persistent expression103,106. AAV is a small parvovirus that does not cause human disease. There are 6 human serotypes and >50 nonhuman serotypes, primarily from nonhuman primates107. The most effective, and most commonly used AAV vectors are serotypes 1,2,5,8,9 and rh.10108. As detailed in 4. Approach, based on evaluation of 25 serotypes, the AAV8 vector was effective in generating high, persistent levels of human AAT in experimental animals. In an embodiment, the composition comprises the AAV8 capsid with a genome that includes the highly active CAG promoter109, an artificial intron, the oxidation resistant human AAT cDNA (described below) and polyA signal (
Expression Cassette.
The AAT coding sequence is based on the normal human M1(Ala213) cDNA, but with modifications at resides 351 and/or 358, to render the AAT protein produced by AAV.vAAT resistant to oxidation. The mature AAT protein is a single chain of 394 amino acids and 3 carbohydrate side chains, with a total MW of 52 kDa110,111. AAT is a globular protein, with the carbohydrate side chains on the opposite end of the Met358 at the active site112 (
The invention provides a composition comprising, consisting essentially of, or consisting of the above-described gene transfer vector and a pharmaceutically acceptable (e.g., physiologically acceptable) carrier. When the composition consists essentially of the inventive gene transfer vector and a pharmaceutically acceptable carrier, additional components can be included that do not materially affect the composition (e.g., adjuvants, buffers, stabilizers, anti-inflammatory agents, solubilizers, preservatives, etc.). Men the composition consists of the inventive gene transfer vector and the pharmaceutically acceptable carrier, the composition does not comprise any additional components. Any suitable carrier can be used within the context of the invention, and such carriers are well known in the art. The choice of carrier will be determined, in part, by the particular site to which the composition may be administered and the particular method used to administer the composition. The composition optionally can be sterile with the exception of the gene transfer vector described herein. The composition can be frozen or lyophilized for storage and reconstituted in a suitable sterile carrier prior to use. The compositions can be generated in accordance with conventional techniques described in, e.g., Remington: The Science and Practice of Pharmacy, 21st Edition, Lippincott Williams & Wilkins, Philadelphia, Pa. (2001).
Suitable formulations for the composition include aqueous and non-aqueous solutions, isotonic sterile solutions, which can contain anti-oxidants, buffers, and bacteriostats, and aqueous and non-aqueous sterile suspensions that can include suspending agents, solubilizers, thickening agents, stabilizers, and preservatives. The formulations can be presented in unit-dose or multi-dose sealed containers, such as ampules and vials, and can be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example, w ater, immediately prior to use. Extemporaneous solutions and suspensions can be prepared from sterile powders, granules, and tablets of the kind previously described. In one embodiment, the carrier is a buffered saline solution. In one embodiment, the inventive gene transfer vector is administered in a composition formulated to protect the gene transfer vector from damage prior to administration. For example, the composition can be formulated to reduce loss of the gene transfer vector on devices used to prepare, store, or administer the gene transfer vector, such as glasses are, syringes, or needles. The composition can be formulated to decrease the light sensitivity and/or temperature sensitivity of the gene transfer vector. To this end, the composition may comprise a pharmaceutically acceptable liquid carrier, such as, for example, those described above, and a stabilizing agent selected from the group consisting of polysorbate 80, L-arginine, polyvinylpyrrolidone, trehalose, and combinations thereof. Use of such a composition will extend the shelf life of the gene transfer vector, facilitate administration, and increase the efficiency of the inventive method. Formulations for gene transfer vector-containing compositions are further described in, for example, Wright et al., Curr. Opin. Drug Discov. Devel., 6(2): 174-178 (2003) and Wright et al., Molecular Therapy, 12: 171-178 (2005))
The composition also can be formulated to enhance transduction efficiency. In addition, one of ordinary skill in the art will appreciate that the inventive gene transfer vector can be present in a composition with other therapeutic or biologically-active agents. For example, factors that control inflammation, such as ibuprofen or steroids, can be part of the composition to reduce swelling and inflammation associated with in vivo administration of the gene transfer vector. Immune system stimulators or adjuvants, e.g., interleukins, lipopolysaccharide, and double-stranded RNA, can be administered to enhance the AAT activity. Antibiotics, i.e., microbicides and fungicides, can be present to treat existing infection and/or reduce the risk of future infection, such as infection associated with gene transfer procedures,
Injectable depot forms are made by forming microencapsule matrices of the subject compounds in biodegradable polymers such as polylactide-polyglycolide. Depending on the ratio of drug to polymer, and the nature of the particular polymer employed, the rate of drug release can be controlled. Examples of other biodegradable polymers include poly(orthoesters) and poly(anhydrides). Depot injectable formulations are also prepared by entrapping the drug in liposomes or microemulsions which are compatible with body tissue.
In certain embodiments, a formulation of the present invention comprises a biocompatible polymer selected from the group consisting of polyamides, polycarbonates, polyalkylenes, polymers of acrylic and methacrylic esters, polyvinyl polymers, polyglycolides, polysiloxanes, polyurethanes and co-polymers thereof, celluloses, polypropylene, polyethylenes, polystyrene, polymers of lactic acid and glycolic acid, polyanhydrides, poly(ortho)esters, poly(butic acid), poly(valeric acid), poly(lactide-co-caprolactone), polysaccharides, proteins, polyhyaluronic acids, polycyanoacrylates, and blends, mixtures, or copolymers thereof.
The composition can be administered in or on a device that allows controlled or sustained release, such as a sponge, biocompatible meshwork, mechanical reservoir, or mechanical implant. Implants (see, e.g., U.S. Pat. No. 5,443,505), devices (see, e.g., U.S. Pat. No. 4,863,457), such as an implantable device, e.g., a mechanical reservoir or an implant or a device comprised of a polymeric composition, are particularly useful for administration of the inventive gene transfer vector. The composition also can be administered in the form of sustained-release formulations (see, e.g., U.S. Pat. No. 5,378,475) comprising, for example, gel foam, hyaluronic acid, gelatin, chondroitin sulfate, a polyphosphoester, such as bis-2-hydroxyethyl-terephthalate (BHET), and/or a polylactic-glycolic acid.
The dose of the gene transfer vector in the composition administered to the mammal will depend on a number of factors, including the size (mass) of the mammal, the extent of any side-effects, the particular route of administration, and the like. In one embodiment, the inventive method comprises administering a “therapeutically effective amount” of the composition comprising the inventive gene transfer vector described herein. A “therapeutically effective amount” refers to an amount effective, at dosages and for periods of time necessary, to achieve a desired therapeutic result. The therapeutically effective amount may vary according to factors such as the extent of AAT deficiency, age, sex, and weight of the individual, and the ability of the gene transfer vector to elicit a desired response in the individual. The dose of gene transfer vector in the composition required to achieve a particular therapeutic effect typically is administered in units of vector genome copies per cell (gc/cell) or vector genome copies/per kilogram of body weight (gc/kg). One of ordinary skill in the art can readily determine an appropriate gene transfer vector dose range to treat a patient having a particular disease or disorder, based on these and other factors that are well known in the art. The therapeutically effective amount may be between 1×1010 genome copies to 1×101 genome copies.
In one embodiment of the invention, the composition is administered once to the mammal. It is believed that a single administration of the composition will result in persistent expression of AAT in the mammal with minimal side effects. However, in certain cases, it may be appropriate to administer the composition multiple times during a therapeutic period to ensure sufficient exposure of cells to the composition. For example, the composition may be administered to the mammal two or more times (e.g., 2, 3, 4, 5, 6, 6, 8, 9, or 10 or more times) during a therapeutic period.
The present invention provides pharmaceutically acceptable compositions which comprise a therapeutically-effective amount of gene transfer vector comprising a nucleic acid sequence which encodes an oxidation-resistant AAT as described above.
Route of Administration.
In the normal humans, AAT is produced mainly by hepatocytes. However, AAT can be produced by many different cells/organs once the gene has been effectively transferred. The routes of administration that have been used for in vivo gene therapy for AAT deficiency include intravenous or intraportal vein (targeting liver hepatocytes), direct administration to skeletal muscle, intrabronchial (targeting the respiratory epithelium) and intrapleural.
All of these routes augment serum AAT levels. However, the challenge for effective AAT gene therapy is to achieve the threshold levels of AAT for successful protection of the alveolar structures from neutrophil proteolytic activity of serum AAT levels of at least about 11 μM in serum and 1.2 μM in alveolar ELF7,8,11,13. To achieve this “biochemical efficacy,” both the serum and ELF protective levels of AAT must be demonstrated. Attempts of gene therapy targeted to the lung via delivery of AAV vector to the respiratory tract epithelium have been frustrated by the anti-pathogen immune and physical defenses of the epithelium, and the deficiency of viral receptors on the respiratory epithelial apical surface122-125. A variety of AAV vectors have been assessed by this route in experimental animals, including serotypes 1, 2, 5, 6, 9, 8, 9, rh.10, rh.20, rh.46, rh.64R1, hu.48R3, cy.5R4, and AAV6.2 (F129L)24,25,30,125-127. None have achieved therapeutic levels, and the respiratory epithelial route has not been developed for clinical trials. The skeletal muscle route has also been evaluated in experimental animals and in human trials using AAV1 and 228,128. The clinical study with AAV2 to treat AAT deficiency, using doses of 2.1×1012-6,9×1013 vector genomes (vg). observed low transient elevations of serum AAT129. A trial using AAV1 with doses up to 6×1012 vg/kg had better success, with levels up to 5% of the target 11 μM20,123,130,131. In experimental animals, administration of AAV vectors by the intravenous route targets primarily the liver. Alternatively, portal vein delivery has been explored. The best results have been with AAV serotypes 8, 9 and 10 (see Chiuchiolo and Crystal103 for review). Neither the intravenous nor intraportal routes has been tested in humans.
AAT deficiency may also be addressed via pleural administration132,133. The pleura presents several structural features that make it an attractive site for gene delivery targeting both the lung parenchyma and systemic circulation, providing a large surface area for gene transfer that is easily accessible. The pleura is a thin serous membrane that encloses the chest cavity attaching to the chest w all (parietal pleura) and to the lung parenchyma (visceral pleura) merging at the chest hilum134,135. The parietal and visceral pleura contain a single layer of mesothelial cells surrounded by a thin layer of connective tissue rich in lymphatic and blood vessels connected to the systemic circulation (
Compositions of the invention delivered to the pleura can genetically modify mesothelial cells lining the pleura and can also provide systemic delivery by vector leaking from the pleura via visceral pleural lymphatics to the systemic venous system and then primarily to liver hepatocytes (
The subject may be any animal; including a human. human and non-human animals. Non-human animals includes all vertebrates, e.g., mammals and non-mammals, such as non-human primates, sheep, dogs, cats, cows, horses, chickens, amphibians, and reptiles, although mammals are preferred, such as non-human primates, sheep, dogs, cats, cows and horses. The subject may also be livestock such as, cattle, swine, sheep, poultry, and horses, or pets, such as dogs and cats.
Preferred subjects include human subjects suffering from or at risk for the AAT deficiency. The subject is generally diagnosed with the condition of the subject invention by skilled artisans, such as a medical practitioner.
The methods of the invention described herein can be employed for subjects of any species, gender, age, ethnic population, or genotype. Accordingly, the term subject includes males and females, and it includes elderly, elderly-to-adult transition age subjects adults, adult-to-pre-adult transition age subjects, and pre-adults, including adolescents, childrens, and infants.
Examples of human ethnic populations include Caucasians, Asians, Hispanics, Africans, African Americans, Native Americans, Semites, and Pacific Islanders. The methods of the invention may be more appropriate for some ethnic populations such as Caucasians, especially northern European populations, as well as Asian populations.
The term subject also includes subjects of any genotype or phenotype as long as they are in need of the invention, as described above. In addition, the subject can have the genotype or phenotype for any hair color, eye color, skin color or any combination thereof.
The term subject includes a subject of any body height, body weight, or any organ or body part size or shape.
The invention will be further described by the following non-limiting examples.
The animal experiments are designed to guarantee unbiased experimental design148. Experimental animals are randomly assigned to groups, and the investigators will be blinded when evaluating animal behavior. Males and females are used to address possible gender differences in AAV transduction, disease manifestation, or therapy response. The numbers of animals in each cohort have been chosen to yield statistically significant data.
Statistical Considerations.
The in vitro studies are performed in triplicate for 3 independent experiments. All data are presented as means±SEM unless otherwise stated. Animal studies are performed with n=5M, 5F mice/group to minimize animal usage while assessing gender difference and giving a reasonable chance that differences can be evaluated. Using a simple (two-sided) power calculation, a two-fold difference can be seen with an alpha of 0.05 and a power of 0.9 if the variance in the measured parameter was 50%, Statistical analysis of clinical pathology is performed using the SAS Software System version 9.2. A t-test will be used for comparison of two groups and ANOVA for more groups to assess treatment-related effects with gender at each time point. Where there was a significant trend across groups (p<0.05) by ANOVA, Tukey's multiple comparison tests is used to assess pairwise differences among all groups, where n=10M and 10F per group.
AAT Levels.
ELISA, using a highly purified AAT standard151. For serum, the AAT levels are expressed as μM. Lung ELF is obtained by fiberoptic bronchoscopy and lavage. The recovered fluid is a mixture of the saline used to recover the ELF and the actual ELF. The volume of recovered ELF is quantified using the urea method165. and the level of AAT expressed in μM using ELF volume as the denominator14.
AAT Function.
Anti-NE capacity±oxidants is assessed using the assays described in
Using the Normal M1(A213) AAT Coding Sequence as a Base, Assess Combinations of Met, Leu, and Val at Positions 351 and 358.
Objectives.
All of the current gene therapy strategies for AAT deficiency deliver the normal human M1 (Val213) cDNA using an AAV gene transfer vector2,19-31,126. The expression cassette of AAV.vAAT is based on M1(Ala213) which 95% of the recipients of AAV.vAAT express and which was derived from the normal M1(Ala213) allele (
1Single letter amino acid code variants at residues 351 and 358.
Detailed Methods.
Site-directed mutagenesis is used to change the methionine residues at amino acid positions 351 and 358 to valine or leucine in the M1(A213) allele cDNA in all possible combinations of single and double variants (Table I). Plasmids encoding for the AAT oxidant variants or the parental AAT will be transfected into 293T cells in serum-free media and the secreted AAT proteins collected in the supernatant after 72 hr. The amount of AAT protein in the supernatant is quantified by ELISA using a highly purified, validated standard151. Two approaches are used to determine the oxidation resistance of AAT candidates. First, the parental AAT and the AAT variants are pre-incubated with increasing concentrations of oxidizing agents such as NCS, H2O2, or cigarette smoke extract before incubation with NE Inhibition of NE is measured by addition of the substrate N-Suc-Ala-Ala-Ala-p-nitroanilide152. The product of NE hydrolysis, p-nitroanilide, is assessed by spectrophotometric measurement at 410 nm. Second, the AAT constructs is pre-incubated with a fixed amount of oxidizing agent for varying amounts of time and then evaluated for their ability to inhibit NE The association rate (Kassoc) is calculated for each of the oxidized AAT variants and parental AAT by determining the inhibition activity as a function of time32,98,153,154. The AAT variants are scored (>85% inhibition—5 points; 70-85%—4; 55-70%—3; 40-55%—2; 25-40%—1; <25%—0) based on their ability to inhibit neutrophil elastase after exposure to oxidizing agents at different concentrations and times. Studies may also be carried out to evaluate variants for inhibition of cathepsin G, another serine protease that is inhibited by AAT and has been show n to play a role in the development of pulmonary emphysema155.
Intrapleural Administration of AAV.vAAT to Experimental Animals Results in Persistent, High Levels of Oxidation-Resistant Human RAT in Serum and Lung Epithelial Lining Fluid.
In a mouse preclinical model, De et al2 demonstrated that an AAV5-based vector expressing human AAT produced high, sustained levels of the protein (1 mg/ml) in serum via the intrapleural route compared to intramuscular administration at the same dose. The therapy approach resulted in levels of AAT in the lung similar to that in serum2. In a comparison of 25 different AAV serotypes in mice, De et al22 demonstrated that 2 Glade E AAV nonhuman primate vectors, AAVrh.10 and AAV8 were the most effective, with intrapleural administration providing high, long term delivery of human normal M type AAT; AAV8 is a bit slower than AAVrh.10, but both made the same level of expression by 4 wk, 2.5-fold above the therapeutic threshold of 11 μM. The Crystal laboratory chose AAVrh.10 for follow up up studies. High serum levels with AAVrh.10 were sustained through 24 wk, the latest point of the study (
AAV.vAAT may comprise the CAG promoter driving an oxidation-resistance, NE inhibiting human AAT coding sequence based on AAT(Ala213) packaged in the AAV8 capsid (
Administration by the intrapleural route provides persistent, high level expression of oxidant-resistant, NE functioning human AAT in serum and lung ELF.
The cDNA from oxidant resistant α1AT constructs are packaged into AAV8 (
In Viva Assessment.
AAV.vAAT is administered at 3 doses (4×1010, 1011, 4×1011) by the intrapleural and intravenous routes to C57Bl/8 mice (C57Bl/6 are used because they do not recognize human AAT as “foreign”)22, with controls AAV8hAAT (the identical vector as AAV.vAAT but with the normal AAT(Ala213) cDNA) and AAV8Null (the identical vector as AAV.vAAT but with no AAT in the expression cassette). Only the highest dose 4×1011 gc is used for the controls. Serum and lung ELF is assessed at 0 (pre-therapy), 14, 28, 90 and 180 days for human AAT levels and anti-NE capacity in the absence or presence of NCS (Table 2).
1All studies with C57Bl/6 mice, n = 5M, 5F at each dose vector, dose and time point (0, 28, 90, 180 days), total n = 400 mice; AAT assays include: human AAT levels (ELISA) and anti-NE capacity in the absence or presence of NCS (see Johnson & Travis1 for details);
2Vectors as defined in the text;
3IP = intrapleural, right side, 100 μl (see De et al2 for details); IV = intravenous, tail vein, 100 μl (see Pagovich et al3 for details). All available data supports the concept that the IP route is superior to the IV route for clade E AAV vectors2, the IV route is included in these studies to insure this holds for AAV.vAAT.
Detailed Methods for a Formal Toxicology Study.
Based on Crystal laboratory recent experience with the FDA and the Crystal laboratory experience with a GMP 1st generation AAVrh, 10 vector (same Glade as AAV8) toxicology study107, and the FDA website guidance that neither the use of multiple species nor nonhuman primates is a default163, we expect that the only required toxicology study will be in nice. The total amount of GMP vector required is 5×1015 gc. The study will evaluate two doses (1011 and 1012 genome copies; 1012 gc is ½ log greater than the likely highest dose scaled to humans) administered by either the intrapleural or intravenous route to C57BL/6 mice to assess; (1) safety following vector administration; (2) biodistribution of the vector; and (3) hα1AT mRNA expression in chest cavity organs (Table 3). General safety, hematology, serum chemistry, histopathology parameters, vector genome distribution and transgene expression will be evaluated at 4 time points (4, 28, 90, 180 days) after a single AAV.vAAT administration.
Table 3 describes a toxicology study. The design is similar to that carried out for IND BB IND 16008 for a 1st generation AAV vector for AAT deficiency (AAVrh.10hAAT), this toxicology study has been published19,162.
1 Administered on day 0 by the interpleural (IP) or intravenous (IV) route, doses 1011 or 1012 gc; the IV group at the highest dose (1012 gc) is used as a worst case scenario of inadvertent IV administration, gc—genome copies.
210 M/10 F at each dose group will be assessed at day 0 (pretherapy) 4, 28, 90 and 180 days for the parameters listed; animals will be assessed twice daiy for morbidity/mortality; body weight assessed pre-dosing and weekly. The list of all parameters and methods will be identical to the GMP toxicology study for the 1st generation AAVrh.10hAAT vector carried out by Chiuchiolo et al19
Many CROs have experience in producing GMP vectors for in viva gene therapy clinical studies and in designing and carrying out formal toxicology studies, including Weill Cornell Belfer Gene Therapy Core Facility (BGTCF; a core facility run by the Crystal laboratory that carries out fee-for-service contract production of GMP gene therapy vectors for academia and industry) as they have experience in producing AAV8 for a clinical trial; and in producing GMP vectors expressing human AAT.
For AAV.vAAT the process uses a two plasmid transfection system in adherent HEK293 cells from highly characterized and qualified cell bank that meets regulatory expectations. Plasmids are kanamycin resistant for selection and compatible with FDA guidelines for manufacturing clinical grade drug. After 5 days, cells are harvested and a crude viral lysate is made by freeze/thaw cycles followed by benzonase digestion to digest host cell derived nucleic acids followed by high salt to quench benzonase and disrupt AAV-cell membrane interactions. The resulting cell harvest is clarified by depth filtration, concentrated by tangential flow filtration (TFF) followed by two steps of membrane ion exchange, buffer exchange on TFF and separation of empty from full capsids by BIA monolith column (
Phase 1 Trial.
A clinical phase I study compares 3 doses, 8×1012, 8×1013 and 4×1014 genome copies administered by the intrapleural route to individuals (n=5 each dose) with a ZZ or Z Null genotype and serum AAT levels <11 μM. Besides the normal safety parameters, the goal of the therapy is to reach a sustained concentration of >1.2 μM AAT in ELF, the lung “protective level”164. The completion of this study provides critical safety and preliminary efficacy data. Most of the parameters in the phase I trial utilize standard clinical assays available in all academic medical hospitals. However, there are also assays relevant to AAV.vAAT function administered to AAT deficient patients, and assays to assess immune response to AAV.vAAT.
All publications, patents and patent applications are incorporated herein by reference. While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purposes of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein may be varied considerably without departing from the basic principles of the invention.
This application claims the benefit of the filing date of U.S. application Ser. No. 62/478,357, filed on Mar. 29, 2017, the disclosure of which is incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US18/25183 | 3/29/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62478357 | Mar 2017 | US |
