Patent Application
20130116180
In general, the invention relates to parathyroid hormone (PTH) analogs, particularly those having long-acting agonist activity at the PTH receptor. These analogs can be used to treat diseases where long-acting activity is desirable, such as hypoparathyroidism.
PTH(1-34) is an effective therapeutic in treatment of osteoporosis and conditions of PTH deficiency, namely hypoparathyroidism. Hypoparathyroidism is a life-long disease characterized by an inadequate production of parathyroid hormone (PTH) by the parathyroid glands. Because PTH is critical for regulation of calcium and phosphate levels, loss of PTH reduces calcium levels in blood and bones and increases phosphate levels (hypocalcemia and hyperphosphatemia). Hypocalcemia leads to symptoms such as neuromuscular irritability, including paresthesias, muscle twitching, laryngeal spasms (which can lead to inability to speak and to alert health providers to the underlying medical condition, which has led to delayed or incorrect treatment), and possibly tetany and seizures. It is the only endocrine disorder in which the missing hormone (namely PTII) is not yet available as therapy.
PTH(1-34) has been identified as a safe and effective alternative to calcitriol therapy for hypoparathyroidism and is able to maintain normal serum calcium levels without hypercalciuria (Winer et al., J Clin Endocrinol Metab 88:4214-4220, 2003). Nonetheless, the polypeptide requires injection at least twice daily, and the need in this disease for a long-acting PTH(1-34) analog has therefore been recognized (Winer et al., supra).
Thus, there exists a need for additional PTH receptor agonists, particularly those having long-acting activity at the PTH receptor.
The present invention relates to the development of PTH and PTHrP analogs. The exemplary polypeptides described herein, SP-PTH-AAK and Aib-SP-PTH-AAK, have long-acting activity at the PTH receptor both in vitro and in vivo and exhibit high solubility in neutral aqueous solution. The polypeptides of the invention are therefore suitable for treatment of disease in which long-acting activity is desired, including hypoparathyroidism.
The invention accordingly features a polypeptide (e.g., isolated), or pharmaceutically acceptable salt thereof, including the amino acid sequence of formula (1):
where X01 is Ser, Ala, or Aib; X03 is Ser, Ala, or Aib; X08 is Met, Leu, or Nle; X10 is Asn, Ala, Val, Asp, Ile, Glu, or Gln; X11 is Leu, Ala, Val, Met, Lys, Arg, Har, or Trp; X12 is Gly, Ala, His, or Arg; X13 is Lys, Ala, Leu, Gln, Arg, His, or Trp; X14 is His, Leu, Arg, Phe, Trp, or Ser; X15 is Ile or Leu; X16 is Gln or Asn; X17 is Asp or Ser; X18 is Ala, Leu, Met, Glu, Ser, or Phe; X22 is Ala, Phe, Glu, Ser, Leu, Asn, Trp, or Lys; X25 is His, Arg, Leu, Trp, or Lys; and X26 is Lys, His, Ala, Ser, Asn, or Arg; or a fragment thereof including amino acids 1-28, 1-29, 1-30, 1-31, 1-32, 1-33, 1-34, or 1-35 of formula (I), with the proviso that at least one of X18 is not Leu or Met, X22 is not Phe, and X26 is not His.
In certain embodiments, the polypeptide includes formula (II):
where X01 is Ser, Ala, or Aib; X03 is Ser, Ala, or Aib; X08 is Met, Leu, or Nle; X10 is Asn, Gln, or Asp; X11 is Leu, Arg, Har, or Lys; X12 is Gly or Ala; X14 is His, Trp, or Ser; X15 is Ile or Leu; X16 is Gln or Asn; X17 is Asp or Ser; X18 is Ala or Leu; X22 is Ala or Phe; and X26 is Lys or His; or a fragment thereof including amino acids 1-28, 1-29, 1-30, 1-31, 1-32, 1-33, 1-34, or 1-35 of formula (II).
In other embodiments, the polypeptide includes formula (III):
where X01 is Ser, Ala, or Aib; X03 is Ser, Ala, or Aib; X08 is Met, Leu, or Nle; X10 is Asn or Gln; X11 is Leu, Arg, or Har; X12 is Gly or Ala; X14 is His or Trp; X16 is Gln or Asn; X17 is Asp or Ser; X18 is Ala or Leu; X22 is Ala or Phe; and X16 is Lys or His; or a fragment thereof including amino acids 1-28, 1-29, 1-30, 1-31, 1-32, 1-33, 1-34, or 1-35 of formula (III).
In particular embodiments of any of the above polypeptides, X01 and X03 are Ala; X10 is Gln; X11 is Arg; X12 is Ala; and X14 is Trp. In other embodiments, X01 is Ala; X03 is Aib; X10 is Gln; X11 is Har; X12 is Ala; and X14 is Trp. In any of the above polypeptides, X18 may be Ala; X22 may be Ala; and/or X26 may be Lys.
In certain embodiments, the polypeptide is substantially identical (e.g., at least 90% or 95% identical) to a polypeptide described above (e.g., where X18 and X22 are Ala and where X26 is Lys). In certain embodiments, the polypeptide exhibits greater solubility in neutral aqueous solution (e.g., phosphate-buffered saline (PBS) at pH 7.4) as compared to SP-PTH (e.g., is at least 40%, 50%. 60%, 70%, 80%, 90%, or 95% as soluble in neutral aqueous solution as compared to in acidic solution (e.g., pH 1, 2, 3, 4 such as 10 mM acetic acid (pH 2.9)). In certain embodiments, the polypeptide is biologically, active (e.g., a PTH receptor agonist). In certain embodiments, the polypeptide binds to the R0 state of the human PTH-1 receptor with an affinity greater than that of hPTH(1-34). In other embodiments, the polypeptide is fewer than 200, 150, 100, 75, 50, 40, 39, 38, or 37 amino acids in length. The polypeptide may be amidated at its C-terminus.
In a particular embodiment, the polypeptide includes or is the amino acid sequence:
or a fragment thereof including amino acids 1-28, 1-29, 1-30, 1-31, 1-32, 1-33, 1-34, or 1-35 of said sequence. In another embodiment, the polypeptide includes or is the amino acid sequence:
or a fragment thereof including amino acids 1-28, 1-29, 1-30, 1-31, 1-32, 1-33, 1-34, or 1-35 of said sequence. In other embodiments, the peptide includes or is an amino acid sequence is selected from the group consisting of:
or a fragment thereof including amino acids 1-28, 1-29, 1-30, 1-31, 1-32, 1-33, 1-34, or 1-35 of said sequence.
Any of the polypeptides described above may be amidated at their C-terminus.
The invention also features a pharmaceutical composition that includes a polypeptide of the invention (e.g., any polypeptide described above or herein) and a pharmaceutically acceptable carrier.
In certain embodiments, the polypeptide of the invention is synthesized by solid-phase synthesis or is produced recombinantly.
The invention also features a method for treating a subject having a disease selected, for example, from the group consisting of hypoparathyroidism, hyperphosphatemia, osteoporosis, fracture repair, osteomalacia, arthritis, and thrombocytopenia. The method includes administering a polypeptide of the invention or a pharmaceutical composition including a polypeptide of the invention to the subject in an amount sufficient to treat the disease. The polypeptide or pharmaceutical composition may be administered, for example, subcutaneously, intravenously, intranasally, transpulmonarily, transdermally, and orally.
The invention also features a nucleic acid including a sequence encoding a polypeptide of the invention. The nucleic acid may be operably linked to a promoter. The nucleic acid may be part of a vector. The invention also features a cell including the vector and a method of making a polypeptide by growing the cell under conditions where the encoded polypeptide is expressed.
By “subject” is meant either a human or non-human animal (e.g., a mammal).
By “treating” is meant ameliorating at least one symptom of a condition or disease in a subject having the condition or disease (e.g., a subject diagnosed with hypoparathyroidism), as compared with an equivalent untreated control. Such reduction in the symptom (e.g., a reduction in blood calcium levels or increase in serum phosphate levels) is at least 5%, 10%, 20%, 40%, 50%, 60%, 80%, 90%, 95%, or 100%, as measured by any standard technique.
By a “purified polypeptide” or “isolated polypeptide” is meant a polypeptide that has been separated from other components. Typically, the polypeptide is substantially pure when it is at least 30%, by weight, free from other components. In certain embodiments, the preparation is at least 50%, 60%, 75%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% by weight, free from other components. A purified polypeptide may be obtained, for example, by extraction from a natural source; by expression of a recombinant polynucleotide encoding such a polypeptide; or by chemically synthesizing the polypeptide. Purity can be measured by any appropriate method, for example, column chromatography, polyacrylamide gel electrophoresis, or by HPLC analysis.
By “biologically active” is meant that the compound or composition (e.g., a polypeptide described herein) has at least one biologically significant effect upon administration to a cell or animal (e.g., a human or non-human mammal). Biological activities of PTH, PTHrP, and analogs thereof (e.g., those described herein) include, without limitation, receptor binding, cAMP or IP3 production, protein kinase A, protein kinase C, phospholipasc C, phospholipase D, and phospholipase A2 activation, changes (e.g., increases or decreases) in intracellular, plasma, or urinary calcium or phosphate levels, and changes in bone metabolism or catabolism in vivo or in vitro. A biologically active polypeptide of the invention (e.g., any polypeptide described herein), for example, may exhibit increases (e.g., at least 5%, 10%, 25%, 50%, 100%, 500%, 1000%, 10,000%) or decreases (e.g., 95%, 90%, 75%, 50%, 25%, 10%, 5%, 1%, 0.1%, 0.01%, or 0.001%) in any biological activity as compared to an appropriate control (e.g., a wild-type polypeptide or a phenocopy thereof such as PTH(1-34) or PTHrP(1-36)).
By “substantially identical” is meant a nucleic acid or amino acid sequence that, when optimally aligned, for example, using the methods described below, share at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity with a second nucleic acid or amino acid sequence, e.g., a PTH or PTHrP sequence or fragment thereof “Substantial identity” may be used to refer to various types and lengths of sequence, such as full-length sequence, epitopes or immunogenic peptides, functional domains, coding and/or regulatory sequences, exons, introns, promoters, and genomic sequences. Percent identity between two polypeptides or nucleic acid sequences is determined in various ways that are within the skill in the art, for instance, using publicly available computer software such as Smith Waterman Alignment (Smith et al., J Mol Biol 147:195-7, 1981); “Best Fit” (Smith and Waterman, Advances in Applied Mathematics, 482-489, 1981) as incorporated into GeneMatcher Plus™, Schwarz and Dayhof (1979) Atlas of Protein Sequence and Structure, Dayhof, M. O., Ed pp 353-358; BLAST program (Basic Local Alignment Search Tool; (Altschul et al., J Mol Biol 215: 403-10, 1990), BLAST-2, BLAST-P, BLAST-N, BLAST-X, WU-BLAST-2, ALIGN, ALIGN-2, CLUSTAL, or Megalign (DNASTAR) software. In addition, those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms needed to achieve maximal alignment over the length of the sequences being compared. In general, for proteins, the length of comparison sequences will be at least 6 or 8 amino acids, preferably 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 40, 50, 60, 70, 80, 90, 100, 125, 150, 200, 250, 300, 350, 400, or 500 amino acids or more up to the entire length of the protein. For nucleic acids, the length of comparison sequences will generally be at least 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96, 99, 102, 105, 108, 111, 125, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 800, 900, 1000, 1100, 1200, or at least 1500 nucleotides or more up to the entire length of the nucleic acid molecule. It is understood that for the purposes of determining sequence identity when comparing a DNA sequence to an RNA sequence, a thymine nucleotide is equivalent to a uracil nucleotide. Conservative substitutions typically include substitutions within the following groups: glycine, alanine; valine, isoleucine, leucine; aspartic acid, glutamic acid, asparagine, glutamine; serine, threonine; lysine, arginine; and phenylalanine, tyrosine.
By “neutral pH” is meant a pH of about 6-9 (e.g., 6.5-8.0). Particular neutral pH values include 6.5, 6.6, 6.8, 7.0, 7.2, 7.4, 7.6, 7.8, and 8.0.
Other features and advantages of the invention will be apparent from the following Detailed Description, the drawings, and the claims.
The present invention relates to new parathyroid hormone (PTH) analogs having prolonged activity at the PTH receptor. These analogs are exemplified by SP-PTH-AAK ([Ala1,3,12,18,22,Gln10,Trp14,Lys26]PTH(1-14)/PTHrP(15-36)) and Aib-SP-PTH-AAK (Ala1,12,18,22,Aib3,Gln10,homoArg11,Trp14,Lys26)). As described below, these polypeptides bind with higher affinity to the non-G protein coupled, R0 conformation of the PTH-1 receptor (PTHR1) in vitro than PTH(1-34) and other reference polypeptides. Accordingly, these polypeptides induce prolonged cAMP signaling responses in cultured cells. These polypeptides also exhibited prolonged increases in blood ionized calcium levels in laboratory test animals (mice, rats, and monkeys) as compared to PTH(1-34) or other test analogs. Because of their confirmed long-acting properties in vivo, the analogs have utility as treatments for conditions such as hypoparathyroidism.
The exemplary polypeptides, SP-PTH-AAK and Aib-SP-PTH-AAK, include an N-terminal portion based on the human PTH(1-14) sequence and a C-terminal portion based on the human PTHrP sequence (see Table 1 below), with both the N- and C-terminal portions containing affinity-enhancing amino-acid substitutions. These polypeptides exhibit surprisingly high binding affinities and cAMP signaling potencies in vitro, as well as enhanced functional effects in vivo, as illustrated in the Examples below. Finally, these polypeptides exhibited high solubility, comparable to the wild-type PTH(1-34) polypeptide, as described below. Based on these properties, these polypeptides can be used in any application where prolonged activity at the PTH receptor is desired, e.g., for the treatment of hypoparathyroidism.
R0 vs. RG binding of PTH agonists
As described in PCT Publication WO 2009/017809, a novel “R0” state of the PTH receptor, in which the receptor is not bound to its G-protein but is capable of agonist binding was identified. Previously it was believed that two forms of a G-protein-coupled receptor could be distinguished: a form (RG) that is bound to a G-protein and a form (R) that is not bound to a G-protein. GPCR signaling requires that the G-protein be directly activated by the receptor, i.e., the RG state must form, and this RG formation can be induced by binding of an agonist ligand. Binding of an agonist ligand induces or stabilizes the RG state, and reciprocally, the RG state stabilizes the high affinity binding of an agonist. Upon binding GTP, or, a non-hydrolyzable GTP analog, such as GTPδS, a receptor-coupled G protein will dissociate from the receptor, causing the receptor to revert to a low affinity state. It is now recognized that some GPCRs, like the PTHR, can form a novel state (R0) that can bind certain agonist ligands with high affinity even in the presence of GTPγS, and hence, even when the receptor is presumably not bound by a G protein. Based on this discovery of the R0 state, PCT Publication WO 2009/017809 describes that ligands which bind with high affinity to the R0 state, in addition to the RG state, have a longer activity half-life than ligands that bind to R0 with lower affinity. This prolonged activity does not depend on the bioavailability or the pharmacokinetics of the ligand in vivo. Correspondingly, agonists with a short duration of action have a lower affinity for the R0 form of the receptor.
As described in the Examples below, SP-PTH-AAK and Aib-SP-PTH-AAK exhibit substantially greater binding to the R0 form of the PTH receptor as compared to hPTH(1-34) in vitro, and exhibit long-acting activity both in vitro and in vivo. The polypeptides of the invention are therefore suitable as long-acting PTH agonists.
The polypeptides of the invention (e.g., SP-PTH-AAK and Aib-SP-PTH-AAK) are amenable to production by solution- or solid-phase peptide synthesis and by in-situ synthesis using combination chemistry. The solid phase peptide synthesis technique, in particular, has been successfully applied in the production of human PTH and can be used for the production of these compounds (for guidance, see Kimura et al., supra and Fairwell et al., Biochem. 22:2691, 1983). Success with producing human PTH on a relatively large scale has been reported in Goud et al., J Bone Min Res 6:781, 1991. The synthetic peptide synthesis approach generally entails the use of automated synthesizers and appropriate resin as solid phase, to which is attached the C-terminal amino acid of the desired polypeptide. Extension of the peptide in the N-terminal direction is then achieved by successively coupling a suitably protected form of the next desired amino acid, using either FMOC- or BOC-based chemical protocols typically, until synthesis is complete. Protecting groups are then cleaved from the peptide, usually simultaneously with cleavage of peptide from the resin, and the peptide is then isolated and purified using conventional techniques, such as by reversed phase HPLC using acetonitrile as solvent and tri-fluoroacetic acid as ion-pairing agent. Such procedures are generally described in numerous publications and reference may be made, for example, to Stewart and Young, “Solid Phase Peptide Synthesis,” 2nd Edition, Pierce Chemical Company, Rockford, Ill. (1984).
Polypeptides of the invention can also be made recombinantly by any method known in the art. Prokaryotic (e.g., bacterial) and eukaryotic (e.g., yeast and mammalian) expression systems can also be used to produce polypeptides of the invention, particularly where the polypeptide includes only amino acids coded for the genome (e.g., not Aib or Har).
Any of the polypeptides described herein (e.g., SP-PTH-AAK and Aib-SP-PTH-AAK) may contain one or more modifications such as N-terminal or C-terminal modifications. Modifications include acetylation, acylation, ADP-ribosylation, amidation, covalent attachment of flavin, covalent attachment of a heme moiety, covalent attachment of a nucleotide or nucleotide derivative, covalent attachment of a lipid or lipid derivative, covalent attachment of phosphotidylinositol, cross-linking, cyclization, disulfide bond formation, demethylation, formation of covalent cross-links, formation of cystine, formation of pyroglutamate, formylation, gamma-carboxylation, glycosylation, GPI anchor formation, hydroxylation, iodination, methylation, myristoylation, oxidation, proteolytic processing, phosphorylation, prenylation, racemization, selenoylation, sulfation, transfer-RNA mediated addition of amino acids to proteins such as aiginylation, and ubiquitination. See, for instance, Proteins-Structure and Molecular Properties, 2nd Ed., T. E. Creighton, W. H. Freeman and Company, New York, 1993 and Wold, F., Posttranslational Protein Modifications: Perspectives and Prospects, pgs. 1-12 in Posttranslational Covalent Modification of Proteins, B. C. Johnson, Ed., Academic Press, New York, 1983; Seifter et al., Methods Enzymol 182:626 646 (1990) and Rattan et al., Ann NY Acad Sci 663A& 62 (1992).
Any of the polypeptides of the invention may further include a heterologous sequence (a fusion partner), thus forming a fusion protein. The fusion protein may include a fusion partner such as a purification or detection tag, for example, proteins that may be detected directly or indirectly such as green fluorescent protein, hemagglutinin, or alkaline phosphatase), DNA binding domains (for example, GAL4 or LexA), gene activation domains (for example, GAL4 or VP 16), purification tags, or secretion signal peptides (e.g., preprotyrypsin signal sequence). In other embodiments the fusion partner may be a tag, such as c-myc, poly histidine, or FLAG. Each fusion partner may contain one or more domains, e.g., a preprotrypsin signal sequence and FLAG tag. In other cases, the fusion partner is an Fc protein (e.g., mouse Fc or human Fc).
Methods for Treatment of Disease
Any disease associated with PTH dysfunction or with calcium or phosphate imbalances, can be treated with the polypeptides described herein (e.g., SP-PTH-AAK and Aib-SP-PTH-AAK). The polypeptides may be used to treat hypoparathyroidism, hyperphosphatemia, osteoporosis, fracture repair, osteomalacia, arthritis, or thrombocytopenia, or may be used to increase stem cell mobilization in a subject. Any mode of administration (e.g., oral, intravenous, intramuscular, ophthalmic, topical, dermal, subcutaneous, and rectal) can be used in the treatment methods of the invention. A physician will determine appropriate dosing for the patient being treated, which will depend in part on the age and size of the patient, the severity of the disease or condition, and the particular disease or condition being treated.
The administration of any polypeptide described herein (e.g., SP-PTH-AAK and Aib-SP-PTH-AAK) may be by any suitable means that results in a concentration of the compound that treats the subject and disease condition. The polypeptide may be contained in any appropriate amount in any suitable carrier substance, and is generally present in an amount of 1-95% by weight of the total weight of the composition. The composition may be provided in a dosage form that is suitable for the oral, parenteral (e.g., intravenously or intramuscularly), rectal, cutaneous, nasal, vaginal, inhalant, skin (patch), ocular, or intracranial administration route. Thus, the composition may be in the form of, e.g., tablets, ampules, capsules, pills, powders, granulates, suspensions, emulsions, solutions, gels including hydrogels, pastes, ointments, creams, plasters, drenches, osmotic delivery devices, suppositories, enemas, injectables, implants, sprays, or aerosols. The pharmaceutical compositions may be formulated according to conventional pharmaceutical practice (see, e.g., Remington: The Science and Practice of Pharmacy, 20th edition, 2000, ed. A. R. Gennaro, Lippincott Williams & Wilkins, Philadelphia, and Encyclopedia of Pharmaceutical Technology, eds. J. Swarbrick and J. C. Boylan, 1988-1999, Marcel Dekker, New York).
Pharmaceutical compositions may be formulated to release the active compound immediately upon administration or at any predetermined time or time period after administration. The latter types of compositions are generally known as controlled release formulations, which include (i) formulations that create substantially constant concentrations of the agent(s) of the invention within the body over an extended period of time; (ii) formulations that after a predetermined lag time create substantially constant concentrations of the agents of the invention within the body over an extended period of time; (iii) formulations that sustain the agent(s) action during a predetermined time period by maintaining a relatively constant, effective level of the agent(s) in the body with concomitant minimization of undesirable side effects associated with fluctuations in the plasma level of the agent(s) (sawtooth kinetic pattern); (iv) formulations that localize action of agent(s), e.g., spatial placement of a controlled release composition adjacent to or in the diseased tissue or organ; (v) formulations that achieve convenience of dosing, e.g., administering the composition once per week or once every two weeks; and (vi) formulations that target the action of the agent(s) by using carriers or chemical derivatives to deliver the compound to a particular target cell type. Administration of the compound in the form of a controlled release formulation is especially preferred for compounds having a narrow absorption window in the gastro-intestinal tract or a relatively short biological half-life.
Any of a number of strategies can be pursued in order to obtain controlled release in which the rate of release outweighs the rate of metabolism of the compound in question. In one example, controlled release is obtained by appropriate selection of various formulation parameters and ingredients, including, e.g., various types of controlled release compositions and coatings. Thus, the compound is formulated with appropriate excipients into a pharmaceutical composition that, upon administration, releases the compound in a controlled manner. Examples include single or multiple unit tablet or capsule compositions, oil solutions, suspensions, emulsions, microcapsules, molecular complexes, microspheres, nanoparticles, patches, and liposomes.
The composition containing polypeptides described herein (e.g., SP-PTH-AAK and Aib-SP-PTH-AAK) may be administered parenterally by injection, infusion, or implantation (subcutaneous, intravenous, intramuscular, intraperitoneal, or the like) in dosage forms, formulations, or via suitable delivery devices or implants containing conventional, non-toxic pharmaceutically acceptable carriers and adjuvants. The formulation and preparation of such compositions are well known to those skilled in the art of pharmaceutical formulation.
Compositions for parenteral use may be provided in unit dosage forms (e.g., in single-dose ampoules), or in vials containing several doses and in which a suitable preservative may be added (see below). The composition may be in the form of a solution, a suspension, an emulsion, an infusion device, or a delivery device for implantation, or it may be presented as a dry powder to be reconstituted with water or another suitable vehicle before use. Apart from the active agent(s), the composition may include suitable parenterally acceptable carriers and/or excipients. The active agent(s) may be incorporated into microspheres, microcapsules, nanoparticles, liposomes, or the like for controlled release. Furthermore, the composition may include suspending, solubilizing, stabilizing, pH-adjusting agents, tonicity adjusting agents, and/or dispersing agents.
As indicated above, the pharmaceutical compositions according to the invention may be in a form suitable for sterile injection. To prepare such a composition, the suitable active agent(s) are dissolved or suspended in a parenterally acceptable liquid vehicle. Among acceptable vehicles and solvents that may be employed are water, water adjusted to a suitable pH by addition of an appropriate amount of hydrochloric acid, sodium hydroxide or a suitable buffer, 1,3-butanediol, Ringer's solution, dextrose solution, and isotonic sodium chloride solution. The aqueous formulation may also contain one or more preservatives (e.g., methyl, ethyl, or n-propyl p-hydroxybenzoate). In cases where one of the compounds is only sparingly or slightly soluble in water, a dissolution enhancing or solubilizing agent can be added, or the solvent may include 10-60% w/w of propylene glycol or the like.
The following examples are intended to illustrate rather than limit the invention.
Exemplary peptides [Ala1,12,Aib3,Gln10,Har11,Trp14]PTH(1-14)/PTHrP(15-36) (Super-potent Aib-PTH: Aib-SP-PTH) and [Ala1,12,18,22,Aib3,Gln10,Har11,Trp14Lys26]PTH(1-14)/PTHrP(15-36) (Super-potent Aib-AAK PTH: Aib-SP-PTH-AAK) were synthesized by the Massachusetts General Hospital Biopolymer Core facility. Aib and Har represent α-aminoisobutyric acid and homoarginine, respectively.
Exemplary peptides [Ala1,3,12,Gln10,Arg11,Trp14]PTH(1-14)/PTHrP(15-36) (Super-potent PTH: SP-PTH) and [Ala1,3,12,18,22,Gln10,Arg11,Trp14Lys26]PTH(1-14)PTHrP(15-36) (SP-PTH-AAK) were synthesized by Sigma Aldrich (Hokkaido, Japan) and American Peptide Company, Inc. (Calif, USA). All polypeptides were dissolved in 10 mM acetic acid and stored at −80° C. Polypeptide concentrations were determined using the PACE method (Pace et al., Protein Science 4:2411-23, 1995) or by amino acid analysis.
Each of these polypeptides is shown in Table 1 below.
Characterization—R0/RG Binding and cAMP Potency
Binding of PTH(1-34), SP-PTH, SP-PTH-AAK, Aib-SP-PTH, and Aib-SP-PTH-AAK to the R0 and RG forms of the PTH-1 receptor was measured using a method as described in PCT Publication WO 2009/017809 or a similar method. Briefly, the R0 form of the receptor can be favored by addition of the non-hydrolyzable nucleotide analog GTPγS. The RG form can be favored, for example, by co-transfection of cells with a negative dominant Gαs subunit. Binding is measured based on displacement of a radioactive tracer ligand (125I-PTH(1-34)). As shown in
RG binding at the rat PTH receptor was also increased in SP-PTII-AAK and Aib-SP-PTH-AAK as compared to hPTH(1-34) (
cAMP stimulating activity of these polypeptides was also assessed, using two different methods: a radioimmunoassay (RIA;
The cAMP-response-element-luciferase response was measured as follows. MC3T3-E1 cells were transfected in 96-well plates with plasmid DNA encoding a luciferase gene fused to a cAMP-Response Element (CRE) promoter, a plasmid construct designed to assess signaling via the cAMP/PKA pathway. At 48 hours after transfection, the cells were incubated at 37° C. for four hours in media containing either vehicle (−14 log M on plot abscissa) or varying concentrations (−13 to −6 log M) of the indicated ligand. Luciferase activity, as luminescence, was then measured using the Promega Steady-Glo reagent and a PerkinElmer Co. Envision plate reader. Data are means of three experiments, each performed in duplicate. The raw basal value obtained in vehicle-treated wells was 9434±11303 counts/second. Curves were fit to the data using Graph-Pad Prism 4.0. The inset in the Figure shows the fit parameters.
Correlation between cAMP potency and either R0 (
The R0 and RG binding experiments were repeated with the human PTH receptor (
cAMP potency assays were also measured using the human receptor (
The ability of SP-PTH-AAK, Aib-SP-PTH-AAK, SP-PTH, and Aib-SP-PTH to stimulate cAMP activity following washing out of the ligand was also tested. cAMP wash-out response assays were performed in MC3T3-E1 cells in 96-well plates as described by Okazaki et al., Proc Natl Acad Sci USA 105:16525-30, 2008. Cells were treated at room temperature with vehicle or the indicated ligand (100 nM) for five minutes; for each ligand duplicate wells were used to obtain the initial (maximum cAMP values); in these wells, cells were co-incubated with ligand and IBMX. After five minutes of initial treatment, the buffer was removed, and, for the initial wells, the reactions were terminated by addition of 50 mM HCl. In the other wells, the cells were rinsed three times with buffer, and incubated in buffer for varying times, as indicated on the abscissa; after which the buffer was replaced by a buffer containing IBMX, and the cells were incubated for another five minutes. After that, the buffer was removed and the reactions were terminated by addition of 50 mM HCl. The cAMP contents of the HCl lysates were then determined by RIA.
As shown in
Studies in Mice
Blood Ca++ responses in mice were also assayed. Mice (C57 BL/6) were injected subcutaneously with either vehicle or the indicated ligand to give a final dose of 5 nmol/kg body weight, and blood was withdrawn via the tail at times after injection and assessed for Ca++ concentration using a Bayer Rapid Lab model 348 blood analyzer. As shown, all polypeptides, including PTH(1-34) exhibited similar calcium levels two hours following administration (
The effects of polypeptides on rats having undergone thyroparathyroidectomy (TPTX) was also tested. Here, five-week-old male Crl:CD(SD) rats were obtained from Charles River Laboratories Japan, Inc. (Kanagawa, Japan) and acclimated for 1 week under standard laboratory conditions at 20-26° C. and 35-75% humidity. The rats were fed free access to tap water and standard rodent chow (CE-2) containing 1.1% calcium, 1.0% phosphate, and 250 IU/100 g of vitamin D3 (Clea Japan, Inc., Shizuoka, Japan).
Thyroparathyroidectomy (TPTX) was performed on six-week-old rats. TPTX rats were selected (<1.0 mM) by serum ionized calcium (iCa) from tail vein bleeding at 24 hours after the operation. TPTX rats were divided into six groups of five or six animals by iCa at 72 hours after the operation. TPTX-vehicle group intravenously received the vehicle (10 mM acetic acid solution) at a dose of 1 ml/kg body weight from tail vein. SP-PTH, SP-PTH-AAK, Aib-SP-PTH, and Aib-SP-PTH-AAK were each intravenously injected into the TPTX rats at doses of 1.25 nmol/kg.
To measure serum calcium and phosphate, rats were anesthetized using Ketamine, and blood was obtained from neck vein at various times (e.g., at 6, 8, 24, 48, and 72 hours) after each injection (
As shown in
The effects of the SP-PTH and SP-PTH-AAK (“SP-AAK”) on serum and urinary calcium and phosphate levels were tested in cynomolgus monkeys. Briefly, three- or four-year-old, male cynomolgus monkeys (HAMRI Co., Ltd., Ibaraki, Japan) were measured for their body weight. Blood was collected into tubes. Monkeys received intravenous or subcutaneous administration of each polypeptide at a dose of 0.3 ml/kg. Polypeptide concentrations in stock solution were adjusted by dilution with 25 mmol/L phosphate-citrate buffer/100 mmol/L NaCl/0.05% Tween 80 (pH.5.0) (PC-buffer). All polypeptides were allowed to stand on ice immediately before administration. Polypeptides were administered to groups of three monkeys each respectively. At 1, 2, 4, and 8 hours after administration, blood was collected by saphenous vein to monitor the time course of calcium and phosphorus levels (
As shown in
Similar experiments were performed using subcutaneous injection of the polypeptides using two different doses (2.5 nmol/kg or 10 nmol/kg;
Solubility
The relative solubilities of SP-PTH-AAK and SP-PTH in different buffers were assessed in an in vitro precipitation assay. For each polypeptide, two vials, each containing 50 μg of lyophilized polypeptide powder, were prepared; one vial was reconstituted in 50 μl of PBS at pH 7.4; the other vial was reconstituted in 50 μl of 10 mM acetic acid (pH 2.9) to give final concentrations of 1.0 mg/ml or 1.5 mg/ml. After one hour at room temperature, the vials were centrifuged at 15,000×g for 2 minutes. The supernatant was removed and the protein content assayed using the Pierce BCA assay (Thermo Fischer Scientific, Rockford, Ill.). For each polypeptide, the content of the PBS sample was expressed as percent of the content of the corresponding acetic acid sample.
As shown in
The activity of SP-PTH-AAK was tested in “knock-in” mice that express a PD PTH receptor in place of the wild-type PTH receptor (Bounoutas et al., Endocrinology 147: 4674, 2006). As explained by Bounoutas, the PD receptors exhibit deficient internalization, which can lead to prolonged cAMP signaling.
Both wild-type PTH(1-34) and the more potent M-PTH(1-28) were tested for their ability to alter blood calcium levels in wild-type and PD mice. As shown in
Blood cAMP levels were also compared between the two types of mice. For wild-type PTH(1-34) and for M-PTH(1-28), blood cAMP levels were increased in magnitude and prolonged in duration in the PD mice as compared to the wild-type mice (
The effect of SP-PTH-AAK on blood calcium levels in wild-type and PD mice is shown in
Repetitive Daily Dosing in TPTX Rats
Our single injection experiments performed in rodents and monkeys revealed biological activities lasting, in some cases, for more than 24 hours, we believe hyperprolonged in these experiments due to the high doses used, as indicated by the marked hypercalcemia. In therapeutic use in humans, one would administer doses sufficient to only normalize blood Ca. A key experiment is to determine if it is indeed feasible to normalize sCa following a repetitive dosing regimen. We thus performed the experiment of FIGS. 20A-2D, in which TPTX rats were treated daily for 10 days with SP-PTH at doses of 1, 2, 4 and 8 nmol/kg (s.c). For comparison, 1,25(OH)2-vitamin-D (calcitriol) at doses of 0.075 and 0.2 mcg/kg (oral) were used for the same time periods. In this study, the 4 nmol/kg dose of SP-PTH gave the most satisfactory control of sCa, as it both avoided hypercalcemia at 8 hours after the last injection (
The data described above are generally represented as the mean standard error (SEM). Statistical significance was determined using SAS software (Ver.5.00.010720, SAS Institute Japan, Tokyo, Japan). A difference in p values of <0.05 was considered statistically significant. *P<0.05, **P<0.01, ***P<0.001.
All patents, patent applications, and publications mentioned in this specification, including U.S. Application Nos. 61/334,319, filed May 13, 2010, and 61/415,141, filed Nov. 18, 2010, are hereby incorporated by reference to the same extent as if each independent patent, patent application, or publication was specifically and individually indicated to be incorporated by reference.
This invention was made with United States Government support under grant DK-11794 awarded by the National Institutes for Health. The Government has certain rights to this invention.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US11/36222 | 5/12/2011 | WO | 00 | 1/22/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 61334319 | May 2010 | US | |
| 61415141 | Nov 2010 | US |
