Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
  • C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
  • C07K14/575—Hormones
  • C07K14/65—Insulin-like growth factors (Somatomedins), e.g. IGF-1, IGF-2
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P17/00—Drugs for dermatological disorders
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P19/00—Drugs for skeletal disorders
  • A61P19/08—Drugs for skeletal disorders for bone diseases, e.g. rachitism, Paget's disease
  • A61P19/10—Drugs for skeletal disorders for bone diseases, e.g. rachitism, Paget's disease for osteoporosis
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P25/00—Drugs for disorders of the nervous system
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P25/00—Drugs for disorders of the nervous system
  • A61P25/28—Drugs for disorders of the nervous system for treating neurodegenerative disorders of the central nervous system, e.g. nootropic agents, cognition enhancers, drugs for treating Alzheimer's disease or other forms of dementia
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P3/00—Drugs for disorders of the metabolism
  • A61P3/08—Drugs for disorders of the metabolism for glucose homeostasis
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P3/00—Drugs for disorders of the metabolism
  • A61P3/08—Drugs for disorders of the metabolism for glucose homeostasis
  • A61P3/10—Drugs for disorders of the metabolism for glucose homeostasis for hyperglycaemia, e.g. antidiabetics
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P43/00—Drugs for specific purposes, not provided for in groups A61P1/00-A61P41/00
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P5/00—Drugs for disorders of the endocrine system
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K38/00—Medicinal preparations containing peptides

Definitions

• the present invention relates generally to compositions and methods for the treatment of conditions responsive to the administration of insulin, human growth hormone, insulin-like growth factor, and/or other proteins that bind to insulin-like growth factor binding proteins.
• the invention is more particularly related to ligand inhibitors that inhibit the binding of insulin-like growth factor to insulin-like growth factor binding proteins, and to the use of such inhibitors for administration (e.g., orally) to patients for the treatment of diabetes, neurodegenerative diseases and other disorders.
• IGFs Insulin-like growth factors
• IGF-I insulin-like growth factors
• IGF-II Two IGFs, known as IGF-I and IGF-II, have been identified, and both have a variety of metabolic actions and affect the growth of multiple cell types (see * e.g.. LeRoith and Roberts, "Insulin-like Growth Factors. " Ann. NY Acad. Sci. 692: 1-9, 1993).
• IGF-I is a 70 amino acid peptide with a molecular weight of 7649 and three disulfide bridges. Its actions in vivo include the mediation of growth hormone actions and bone deposition and maturation.
• IGF-I also mimics the action of insulin, and the IGF-I receptor has high homology to the insulin receptor.
• IGF-II is strongly homologous to IGF-I and this factor plays a role in. for example, bone remodeling and brain cell maintenance and differentiation.
• IGFBP IGF binding protein
• IGFBP 1-IGFBP6 IGF binding protein 1-IGFBP6
• IGFBP 1-IGFBP6 Six related BPs are known and have been designated IGFBP 1-IGFBP6 (see, e.g., Holly and Martin, "Insulin-like Growth Factor Binding Proteins: A Review of Methodological Aspects of Their Purification. Analysis and Regulation," Growth Regul. 4(Suppl l):20-30, 1994; Langford et al., "The Insulin-like Growth Factor- I/Binding Protein Axis: Physiology, Phytophysiology and Therapeutic Manipulation," Eur. J. Clin. Invest.
• BPs play an important role in IGF regulation by exerting inhibitory and/or stimulatory effects on IGF action.
• IGF-I is present in a trimolecular complex containing IGFBP-3 and acid labile subunit (ALS).
• ALS acid labile subunit
• the IGF-I within such complexes is unable to bind to surface receptors, and is therefore biologically inactive.
• IGF-I present within the trimolecular complex also has a substantially longer half-life than uncomplexcd IGF-I. Attempts have been made to treat a wide variety of diseases by administration of IGF-I, IGF-II or an IGF binding protein.
• IGF-I for the treatment of cardiac disorders, intestinal disorders and osteoporosis are described in U.S. Patent No. 5,126,324, WO 91/12018 and European Patent Application 560,723, respectively, and the use of IGF-I for enhancing growth is described in U.S. Patent No. 5,126,324.
• IGF-I has also been studied for use in treating insulin-resistant states and diabetes (see, e.g. , Clcmmons and Underwood, "Uses of Human Insulin-Like Growth Factor-I in Clinical Conditions," J. Clin Endocrinol. Metab.
• treatment with intravenous IGF or antibodies thereto generally requires repeated intravenous injection, resulting in a high cost and practical difficulties for patients.
• Such treatments can also induce side effects due, for example, to the inability to target specific tissues within the body. Further, the scope of treatment is limited to the tissues that may be reached by intravenous hormone administration.
• the present invention provides therapeutic and screening methods employing ligand inhibitors that inhibit the binding of proteins such as insulin- like growth factors to insulin-like growth factor binding proteins.
• the present invention provides a method for increasing the level of free, biologically active insulin-like growth factor in a patient, comprising administering to a patient one or more ligand inhibitors that inhibit the binding of an insulin-like growth factor to one or more insulin-like growth factor binding proteins, and thereby increasing the level of free, biologically active insulin-like growth factors within the patient.
• methods for treating an IGF-responsive condition in a patient, comprising administering to a patient one or more ligand inhibitors that inhibit the binding of an insulin-like growth factor to one or more insulin-like growth factor binding proteins, and thereby alleviating an IGF-responsive condition in a patient.
• the present invention provides a pharmaceutical composition comprising: (a) one or more ligand inhibitors that inhibit the binding of an insulin-like growth factor to one or more insulin-like growth factor binding proteins; and (b) a physiologically acceptable carrier.
• the present invention provides a method for screening for a small molecule inhibitor that inhibits binding of an insulin-like growth factor to an insulin-like growth factor binding protein, comprising: (a) combining an insulin-like growth factor with an insulin-like growth factor binding protein in a solution containing a candidate small molecule, such that the binding protein and the growth factor are capable of forming a complex; and (b) determining the amount of complex in the solution, relative to a predetermined level of binding in the absence of the small molecule, and therefrom evaluating the ability of the small molecule to inhibit binding of an insulin-like growth factor to an insulin-like growth factor binding protein.
• methods for increasing the level of a free protein in a patient, comprising administering to a patient one or more ligand inhibitors that inhibit the binding of a protein to one or more insulin-like growth factor binding proteins, and thereby increasing the level of the free protein within the patient.
• Figure 1 is a graph that depicts the relative amount of binding, expressed as cpm, of l25 I-labeled IGF-I tracer to IGFBP-3, in the presence of varying amounts of [T591HIGF-I, hIGF-I and [L24,59,60,A31]hIGF-I.
• Figure 2 is a graph that presents the relative amount of DNA synthesis, expressed as cpm of inco ⁇ orated [ 3 H]-thymidine, of 3T3 cells in the presence of varying amounts of [T591hIGF-I and [L24,59,60,A31]hIGF-I.
• Figure 3 is a graph that depicts the relative amount of DNA synthesis, expressed as cpm of inco ⁇ orated [ ⁇ HJ-thymidine, of 3T3 cells in the presence of medium only (column 1), 10 nM [T59]hIGF-I (column 2) and 10 nM [T59]hIGF-I plus 25 nM IGFBP-3 (column 3).
• the figure also shows the relative amount of DNA synthesis in the presence of 10 nM [T59]hIGF-l plus 25 nM IGFBP-3, with the addition of varying amounts of [L24,59,60,A31 ]hIGF-l.
• Figure 4 is a graph that shows the decrease in blood glucose levels (in mg/dl) over time (expressed in minutes) following administration of [L24,59,60,A31]hIGF-l to diabetic NOD mice.
• Figure 5 is a pair of graphs that depict the effect of insulin and IGFBP3-LI ([L24,59,60, ⁇ 31 ]hIGF-I) on plasma glucose in rats treated systemically with glucose.
• the present invention is generally directed to methods employing ligand inhibitors for increasing the level of a free protein, such as biologically active IGF, in one or more tissues within a patient.
• the proteins affected by ligand inhibitors as described herein are generally proteins that bind to one or more IGF binding proteins. Increasing the level of such a protein within a patient may generally be useful in the treatment of a variety of conditions.
• IGF refers to one or more insulin-like growth factors (i.e., IGF-I and/or IGF-II). IGFs are peptide hormones, and the sequences of IGF-I and IGF-II in humans and other species have been determined.
• Human IGF-I (hIGF-I) is a 70 amino acid peptide which has the sequence shown in Figure 1 (SEQ ID NO: l ).
• Free protein such as IGF, refers to protein that is not complexed or bound to an IGF binding protein.
• An "IGF binding protein” (IGFBP or BP) is any protein that binds to
• IGF-I and/or IGF-II in vivo, resulting in the inhibition of IGF binding to one or more cell surface receptors, or soluble forms thereof.
• a BP binds to IGF (i.e., forms a complex) through noncovalent interactions.
• IGF binding proteins contemplated within the context of the present invention include IGFBP-1 , -2, -3, -4, -5 and -6.
• IGFBP-3 the most abundant binding protein in adult serum, has a high affinity for both IGF-I and IGF-II. Binding to IGFBP-3 increases the half life of IGF-I from about 10 minutes to approximately 15 hours (sec Langford and Miell, Eur J. Clin. Invest.
• a "ligand inhibitor,” within the context of the present invention, is any molecule (other than an antibody to IGF-I or IGF-II) that is capable of inhibiting the binding of one or more proteins, especially IGF-I and/or IGF-II, to one or more IGFBPs. Due to the similarity between the structures of IGF-I and IGF-II, it will be apparent that many ligand inhibitors will inhibit the binding of both IGF-I and IGF-II to an IGFBP. In some cases, the binding of one IGF will be inhibited to a greater extent than that of the other IGF.
• a ligand inhibitor may be specific for IGF-I or IGF-II.
• a ligand inhibitor may displace IGF from a complex with a BP, thereby causing bound IGF to become free IGF. Such displacement may be reversible or irreversible.
• a ligand inhibitor may also block the binding of free IGF to a BP because of a high affinity for either IGF or one or more BPs. For example, a ligand inhibitor may bind to IGF within a BP binding site, or may bind to a BP at an IGF binding site.
• a ligand inhibitor may bind to IGF or a BP at a site that is not such a binding site, and inhibit complex formation through an allosteric interaction.
• a ligand inhibitor having a lower affinity for IGF or one or more BPs may also inhibit the binding of free IGF to a BP when present at high enough concentrations. Similar mechanisms of inhibition may also be observed for ligand inhibitors directed against other proteins that bind to a BP.
• a molecule "inhibits" binding of a protein to an IGFBP if the level of free protein increases by about 10-30% or more.
• An increase in the level of free protein may generally be detected using a variety of assays known to those of ordinary skill in the art, such as imaging, radioimmunoassays and precipitation techniques as described herein.
• imaging, radioimmunoassays and precipitation techniques as described herein.
• the characteristics of the ligand inhibitor are such that it has a 100 fold selectivity to the IGFBP (K s ⁇ 10 nM).
• Ligand inhibitors include, but are not limited to, analogs of IGF-I or IGF-II and small molecule inhibitors.
• An IGF “analog” is a peptide that has an amino acid sequence that is substantially identical lo a native IGF sequence, but that has one or more amino acid substitutions and/or modifications. Such substitutions and/or modifications may reduce the biological activity of the peptide (i.e.. decrease the affinity of the peptide for one or more cell surface receptors) without decreasing the ability of the peptide to bind to one or more BPs.
• a "small molecule inhibitor” is a ligand inhibitor that is a natural or synthesized non-peptide, organic molecule.
• Small molecule inhibitors are typically identified by screening libraries obtained from soil samples, plant extracts, marine microorganisms, fermentation broth, fungal broth, pharmaceutical chemical libraries, combinatorial libraries (both chemical and biological) and the like. Such libraries may be obtained from a variety of sources, both commercial and proprietary.
• One preferred ligand inhibitor of the present invention is the [L24,A31,L59,L60J analog of hIGF-I.
• This analog (which has the sequence recited in SEQ ID NO:2) binds to IGFBP-3, but not to the IGF-I cell surface receptor.
• [L24,A31 ,L59,L60]hIGF-I may generally be prepared by techniques well known to those of ordinary skill in the art, such as by chemical synthesis. It will be apparent to those of ordinary skill in the art that modifications may be made to the sequence of [L24,A31 ,L59,L60]hIGF-I such that the ability of the analog to inhibit the binding of IGF-I to IGFBP-3 is retained.
• variants are within the scope of the present invention, and may generally be identified by modifying the sequence and evaluating the inhibitory properties of the analog as described below.
• a variant contains conservative substitutions, (i.e., one in which an amino acid is substituted for another amino acid that has similar properties, such that one skilled in the art of peptide chemistry would expect the secondary structure and hydropathic nature of the polypeptide to be substantially unchanged).
• Amino acids suitable for conservative substitutions include those having functionally similar side chains. For example, a hydrophobic residue (e.g., glycine, alanine, valine, leucine, isoleucine and methionine) may replace another such residue.
• conservative substitutions may involve interchanging hydrophilic residues (e.g., arginine and lysine, glutamine and asparagine, threonine and serine), basic residues (e.g., lysine, arginine and histidine), and/or acidic residues (e.g., aspartic acid and glutamic acid).
• Variants may also (or alternatively) be modified by, for example, the deletion or addition of amino acids, or the chemical modification of amino acids, that have minimal influence on the inhibitory properties of the analog.
• Small molecule inhibitors according to the present invention may be prepared using methods well known to those of ordinary skill in the art.
• a chemical library of small molecules as described above may be screened using a binding assay designed to detect molecules that displace a protein such as IGF from a binding protein.
• a complex of radiolabeled IGF-I and a binding protein such as BP-3 may be incubated in the presence of a candidate small molecule.
• Complexes i.e., noncovalent associations of IGF and binding protein
• IGF-I, IGF-II and binding proteins for use in such assays may generally be prepared by techniques known to those of ordinary skill in the art, such as those provided in Rechler, Vitamins and Hormones 47:1-1 14, 1993, and references cited therein. Appropriate techniques include chemical synthesis (described, for example, in Shimasaki et al., J. Biol. Chem.
• IGF and binding proteins employed may be the native proteins, or may contain modifications, such as the addition of label or the addition or deletion of sequences that have minimal effect on the binding properties of the protein.
• Antibodies suitable for use in ELISA assays are commercially available from, for example, Amano Pharmaceutical Co.
• Monoclonal antibodies may be prepared, for example, using the technique of Kohler and Milstein, Eur. J. Immunol. (5:51 1-519, 1976. and improvements thereto.
• a secondary bioassay based on the activity of the binding protein of interest, may also be employed for further characterization of a small molecule inhibitor or other ligand inhibitor.
• IGF-1 stimulates 3T3 fibroblast proliferation in vitro.
• the addition of a binding protein inhibits this stimulation, and the level of inhibition can be determined using [ ljthymidine inco ⁇ oration assays well known to those of ordinary skill in the art.
• Molecules that are capable of reversing the binding protein inhibition are ligand inhibitors.
• Similar assays may be designed for use with specific binding proteins based on the known biological properties of the binding proteins (e.g., the inhibition of granulosa cell steroidogenesis as described in Bicsak et al., Endocrinol. 72(5:2184-2189, 1990).
• Animal models may be useful for further characterization of ligand inhibitors.
• the effect of a ligand inhibitor on blood glucose levels may be evaluated using animals, such as rats.
• An inhibitor that normalizes blood glucose levels in hyperglycemic or diabetic animals may be useful for the treatment of diabetes.
• growth hormone deficient animals may be used to evaluate the utility of a ligand inhibitor for the treatment of conditions that respond to the administration of human growth hormone, such as human growth hormone resistance.
• Ligand inhibitors of the present invention may generally be used to increase the level of free, biologically active IGF in a patient and to treat any of a variety of IGF-responsive conditions.
• IGF-responsive condition encompasses any condition of a patient that may be alleviated or treated by the administration of IGF, and includes diseases such as diabetes (insulin dependent, non- insulin dependent and type I/II), growth retardation, osteoporosis, human growth hormone resistance, ALS, demyelinating diseases (including via remyelination), multiple sclerosis, muscular dystrophy, stroke, ophthalmic conditions, infertility, Alzheimer's disease and other dementias.
• diabetes insulin dependent, non- insulin dependent and type I/II
• growth retardation growth retardation
• osteoporosis human growth hormone resistance
• ALS demyelinating diseases (including via remyelination)
• multiple sclerosis muscular dystrophy
• stroke ophthalmic conditions
• infertility Alzheimer's disease and other dementias.
• IGF-responsive condition also encompasses states in which it is desirable to induce wound healing or bone repair, such as bone remodeling.
• a "patient” refers to any warm-blooded animal, preferably a human.
• a patient may or may not be afflicted with an IGF- responsive condition. Patients that are so afflicted may generally be identified through clinical diagnosis according to methods that are well known to those of ordinary skill in the art.
• the minimum acceptable increase in the level of free IGF is 10%, a preferred level is at least 50% and a particularly preferred level is at least 80%.
• the level of free IGF may generally be determined by methods known in the art, such as resolving the plasma sample to different molecular size fractions on a Sephadex G-50 fine column developed in 0.02M potassium phosphate buffer, pH 7.2.
• the free IGF-I with a molecular weight of 7.6 kDa will elute later than the larger molecular weight IGF-I/IGFBP complex.
• the free IGF-I fraction can then be quantitated by radioimmunoassay.
• blood glucose levels may be used as an indirect measurement of free IGF levels.
• ligands e.g., "C or 1 F
• a single photon-emitting ligand e.g., 12 T-labeled ligand to IGF-binding proteins or IGF receptors.
• Free IGF levels are correlated to the amount of binding of the radiolabeled ligand.
• An increase in IGF levels is manifested by a decreased binding of the radiolabeled ligand to the IGF-binding proteins and IGF receptors.
• an increase in free IGF levels of about 10-30% or more is sufficient.
• the ligand inhibitors are preferably inco ⁇ orated into pharmaceutical compositions, which comprise a therapeutically effective amount of one or more ligand inhibitors and a physiologically acceptable carrier.
• a "physiologically acceptable carrier” may be any composition, carrier or diluent that is capable of administration to a mammal without producing undesirable physiological effects, such as nausea, dizziness or gastric upset. While any suitable carrier known to those of ordinary skill in the art may be employed in the pharmaceutical compositions of this invention, the type of carrier will vary depending on the mode of administration.
• the pharmaceutical compositions may be administered by injection (e.g., intracutaneous, intramuscular, intravenous or subcutaneous), intranasally (e.g., by aspiration) or orally.
• the carrier preferably comprises water, saline, alcohol, a fat, a wax and/or a buffer.
• a solid carrier such as mannitol, lactose, starch, magnesium stearate, sodium saccharine, talcum, cellulose, glucose, sucrose, and magnesium carbonate, may be employed.
• Small molecule inhibitors of the present invention are preferably capable of oral administration in, for example, capsule or tablet form.
• Such ligand inhibitors have the advantage of decreased cost and increased convenience, as compared to conventional treatments that rely on repeated intravenous injection.
• the ability of a small molecule inhibitor to be administered orally may be determined by in vivo assays.
• Such assays typically measure the decrease in the level of IGF bound to binding proteins in response to oral administration of the small molecule inhibitor.
• the amount of small molecule inhibitor in the blood may be measured based on its ability to inhibit binding of l25 l-hIGF-I to IGF binding proteins. Blood samples may be drawn at various times after administration of small molecule inhibitor or vehicle to animals or humans.
• the ligand inhibitor may be extracted from the blood by standard procedures (e.g., 80% acetonitrile/0.1 % trifluoroacetic acid). Briefly, 1 L of the extraction solvent may be added to 200 ⁇ L of plasma and the mixture is vortexed. The resultant precipitate may then be centrifuged at 12,000 x g for 5 minutes. The supernatant containing the ligand inhibitor may then be lyophilized and reconstituted in assay buffer (PBS containing 0.2% Nonidet P-40TM) to yield a reconstituted extract. Blood samples or reconstituted extracts may then be used in a binding assay, such as that described in Example 1 , below. Ligand inhibitors capable of oral administration will show inhibition of binding of ,25 I-hIGF-I to IGF binding proteins, relative to the vehicle control.
• assay buffer PBS containing 0.2% Nonidet P-40TM
• a suitable dose is an amount of ligand inhibitor that, when administered as described above, is capable of improving the clinical outcome for a patient (e.g., fewer hypoglycemic episodes for diabetic patients) in treated patients as compared to untreated patients.
• the amount of each ligand inhibitor present in a dose ranges from about 0.1 to about 10, preferably from about 1 to about 3 mg/kg. A larger or smaller amount may, however, be employed, depending on the size of the ligand inhibitor.
• Treatments are typically conducted one-two times per day, and may need to be continuous for retention of benefit. Patients may be monitored by assessing IGF levels as described above and by evaluating clinical symptoms.
• a significant advantage of the present invention lies in the ability to vary the potency of the pharmaceutical composition and to target IGF effects to specific tissues, minimizing side effects.
• the potency may be varied through the use of ligand inhibitors with varying abilities to inhibit the binding of IGF to one or more binding proteins.
• the relative abilities of ligand inhibitors to inhibit binding may be evaluated by, for example, comparing the amount of inhibitor needed for half maximal displacement of specific binding in an in vitro binding assay as described herein.
• IGF effects may be targeted by using ligand inhibitors that are specific for one or more particular binding proteins, and exploiting the relative tissue specificity of each of the six known binding proteins (see Rechler, Vitamins and Hormones 47: 1 -1 14, 1993).
• Binding protein-specific ligand inhibitors may be developed, as noted above, by using different binding proteins within the binding assay described herein for the identification of small molecule inhibitors. Administration of such ligand inhibitors results in the release of IGF in only those tissues that contain the targeted binding proteins. For example, IGFBP-2, -4 and -6 are more prevalent in the brain. In addition, IGFBP- 1 is present in the brain, although at lower concentrations. Small molecule inhibitors that are specific for these binding proteins and are capable of crossing the blood/brain barrier (as discussed below) will release IGF in the brain, while leaving most of the serum IGF in its inactive form.
• Such inhibitors may be particularly useful for the treatment of ALS and other neurodegenerative diseases such as multiple sclerosis, demyelinating disease and Alzheimer's disease.
• peripheral effects may be manipulated using primarily IGFBP-1 , -3, -4, and -5.
• IGFBP-1 IGFBP-1 , -3, -4, and -5.
• circulating IGF-I may be released by inhibiting binding to IGFBP-3.
• small molecule inhibitors that are not capable of crossing the blood/brain barrier are particularly well suited for providing peripheral effects.
• the amount of a small molecule inhibitor that crosses the blood/brain barrier may be assessed by techniques known to those of ordinary skill in the art, such as MRI, PETSCAN, spectacanning or other similar imaging techniques, some of which use radiolabeled ligand to IGF binding proteins or IGF receptors.
• a preferred method is image analysis using PET positron-emitting ligands (e.g. , "C or 18 F) of a single photon-emitting ligand (e.g., 12 T-labeled ligand to IGF-binding proteins or IGF receptors). Decreased binding of the radiolabeled ligand to the IGF-binding proteins and IGF receptors indicates an increase in IGF levels.
• IGF-I levels in the cerebrospinal fluid can be measured by radioimmunoassay using commercially available assay kits (e.g.. Peninsula Laboratories, Inc., Belmont, CA) or by polyethylene/glycol precipitation, as described in Example 1.
• An increase in the level of IGF-I in the CSF is indicative of an increase in the level of IGF-I in the brain.
• animals In animals, the blood/brain penetration of the small molecule inhibitors can be tested by ex vivo binding. Briefly, animals may be injected (intravenously or orally) with 15-50 mg/kg of a small molecule ligand inhibitor. The animals are then sacrificed at 15, 30, 60 and 90 minutes after administration of the drug. The brains are removed and homogenized in solubilization buffer (PBS containing 0.2% Nonidet
• the assay is then carried out by polyethyleneglycol precipitation of the bound 125 I-hIGF/hIGFBP-3 complex. If any drug is present in the brain, it will inhibit binding of the l 5 I-hIGF-I to the IGF binding proteins, resulting in fewer precipitated counts in the drug-treated animals than in animals treated with vehicle alone.
• liver BP-1 placenta liver BP-2 CSF, CNS, liver BP-3 ovary, adrenal, heart, kidney, liver, stomach, intestine BP-4 liver, brain cortex BP-5 liver, brain, lung, heart, spleen, stomach, kidney, adrenal, intestine
• This Example illustrates the in vitro and in vivo inhibition of binding of IGF-I to BP-3, resulting in increased levels of free, biologically active IGF-I.
• the binding assay was performed in duplicate at room temperature in 0.2%) BSA-PBS, pH 7.2.
• BP-3 was purified from rat serum as described in Shimonaka et al., Biochem. Biophys. Res. Comm. 765: 189-195, 1989.
• Two hundred microliters of a 2.5 nM BP-3 solution (0.5 pmol) was added to a 12 x 75-mm glass tube.
• the reaction was started by the addition of an increasing concentration of unlabeled [T59]hIGF-I or [L24,59,60,A31]hIGF-I (both prepared by chemical synthesis according to the procedure described in Shimasaki et al., J. Biol. Chem.
• This assay may also be employed to screen for small molecule ligand inhibitors.
• BALB/c 3T3 cells were trypsanized and diluted to 50,000 cells per mL in 10%) calf serum-DMEM. The cells were aliquoted to 96-well microtiter plates (180 ⁇ L/well). After 48 hours incubation at 37°C and 5% CO 2 , the plates were washed twice with 0.1% calf serum-DMEM and incubated for an additional 24 hours. To each well, 20 ⁇ L of sample(s) containing IGF analog and/or binding protein and 1 ⁇ Ci [ 3 H]- thymidine were added and the plates were incubated for precisely 24 hours. After the incubation, the medium was removed and the cells were fixed by adding 200 ⁇ L of 25% acetic acid-75% ethanol per well.
• the plates were washed tliree times with cold 10%> TCA and the cells in each well were lysed in 200 ⁇ L 0.2M NaOH. The entire 200 ⁇ L of lysed solution was transferred into a scintillation vial and 2.5 mL scintillation liquid was added and the vials counted in a ⁇ -counter.
• This assay may also be employed to evaluate the biological activity of small molecule ligand inhibitors.
• Example 2 This assay may also be employed to evaluate the biological activity of small molecule ligand inhibitors.
• This Example illustrates the use of ligand inhibitors of IGFBP-3 for the treatment of animals with elevated blood glucose.
• Rats were made hyperglycemic with an intraperitoneal injection of glucose.
• the [L24,59,60,A31]hIGF-l analog (noted as IGFBP3-LI) (5 ⁇ g/min) was infused intravenously for 40 minutes and blood glucose levels were monitored before, during and after the infusion.
• bovine insulin was infused at 1 ⁇ g/min for 40 minutes and blood glucose was monitored at the same time points.
• This Example illustrates the use of ligand inhibitors of IGFBP-3 for the treatment of diabetes in animals.
• mice Two severely diabetic female NOD mice with blood glucose levels of 450-500 mg/dl were treated with the [L24,59,60,A31 ]hIGF-I analog. These mice were severely diabetic and were expected to die within two days without treatment.
• the [L24,59,60,A31]hIGF-I analog was administered at time 0 (25 ⁇ g/animal), at 30 minutes (50 ⁇ g/animal) and at 60 min (100 ⁇ g/animal) by tail vein injection in physiological saline). Blood glucose levels were monitored using a glucometer before the initial injection and throughout the time course of the experiment.

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