WO1999047157A1

WO1999047157A1 - Use of il-10 to treat major depressive disorder

Info

Publication number: WO1999047157A1
Application number: PCT/US1999/003743
Authority: WO
Inventors: Paul Glue; Newell Mcelwee
Original assignee: Schering Corporation
Priority date: 1998-03-17
Filing date: 1999-03-16
Publication date: 1999-09-23
Also published as: AU3063899A

Abstract

Methods are provided for using human IL-10 to treat major depressive disorders, including such disorders that are resistant to treatment with other antidepressant agents. The IL-10, which is preferably recombinant human IL-10, can be administered alone, or in combination with psychotherapy or electroconvulsive therapy and/or with other antidepressant agents.

Description

USE OF IL-10 TO TREAT MAJOR DEPRESSIVE DISORDER

FIELD OF THE INVENTION

This invention relates to the use of interleukin- 10

(IL-10) for the treatment of major depressive disorder, including treatment-resistant depression.

BACKGROUND OF THE INVENTION

Depression is a pathological mood state, characterized by low mood, diminished energy and appetite, altered sleep patterns, and other symptoms. For reviews of the diagnostic symptoms of major depression and some methods of treatment commonly employed, see Bhatia et al., Am. Fam. Physician 55 : 1683- 1698 ( 1997) ; Cunningham, Compr. Ther. 23 :400-406 ( 1997). In severe cases, patients may experience hallucinations and delusions, and m ay attempt suicide. Major depressive disorder is one of the most common severe mental illnesses, with point prevalence of -3%, and lifetime risk of -16%.

Treatment with antidepressant drugs is beneficial in up to 75% of patients. In the -25% of patients who are not responsive to antidepressants, a range of alternative treatment strategies h ave been developed (e.g. augmentation of antidepressant effects with lithium, electroconvulsive therapy). Treatment of these patients, however, is generally difficult, expensive and time-consuming. We are aware of no drugs that are approved for treatment- resistant depression.

There thus is a need for improved methods for treating major depressive disorder, particularly treatment-resi stant depression.

SUMMARY OF THE INVENTION

The present invention fills the foregoing need by providing materials and methods for treating major depressive disorder. More particularly, this invention provides a method for treating 2 major depressive disorder, especially treatment-resistant depression, comprising administering a depression-alleviating amount of IL- 10 to an individual afflicted with major depressive disorder.

In some embodiments, the methods further comprise co-administering one or more other antidepressant agents or methods of treatment with the IL-10.

BRIEF DESCRIPTION OF THE FIGURES

This invention can be more readily understood by reference to the Detailed Description and Example below, and to th e accompanying Figures, in which:

Fig. 1 is a graphical representation of the effect of placebo and varying doses of IL-10 on changes in mental health (MH) scores in Crohn's Disease patients. Results are shown for patients with baseline MH<40 (-•-), and with baseline MH>40 (-0-).

Fig. 2 is a graphical representation of the effect of placebo and varying doses of IL-10 on baseline Crohn's Disease Activity

Index (CDAI) scores in Crohn's Disease patients. Results are shown for patients with baseline MH<40 (-•-), and with baseline MH>40 (-0-) .

Fig. 3 is a graphical representation of the effect of placebo and varying doses of IL-10 on changes in baseline CDAI scores i n Crohn's Disease patients. Results are shown for patients with baseline MH<40 (-•-), and with baseline MH>40 (-0-).

DETAILED DESCRIPTION OF THE INVENTION

All references cited herein are hereby incorporated in their entirety by reference.

As used herein, "interleukin- 10" or "IL-10" is defined as a protein which (a) has an amino acid sequence substantially identical to a known sequence of mature (i.e., lacking a secretory leader sequence) IL-10 as disclosed in U.S. Patent No. 5,231 ,012, and (b) has biological activity that is common to native IL- 10. 3 This definition also includes truncated analogs, which can b e prepared through routine experimentation by deleting successive amino acid residues from the amino- and/or carboxyl-terminus until biological activity is lost, and conjugates of IL- 10 with o ther molecules.

Such conjugates include, e.g., conjugates to polyethylene glycol (PEG; see, e.g., European Patent Application Publication No. 0 510 356 Al ) or to human immunoglobulin chain constant regions (see, e.g., International Patent Application Publication No. WO 96/18412) and the like, which may increase the duration of action of the IL-10.

For the purposes of this invention, both glycosylated an d unglycosylated IL- 10 are considered equivalent and can be u sed interchangeably. Also included for use in this invention are muteins, IL-10 variants having conservative amino acid substitutions, such as replacement of a valine with a leucine residue or a glutamate with an aspartate residue etc., and the BCRFI (Epstein Bar Virus viral IL- 10) protein, all of which possess the biological activity of IL-10. See, e.g., U.S. Patent No. 5,231 ,012.

IL- 10 suitable for use in the invention can be obtained from a number of sources. For example, it can be isolated from culture media conditioned by activated T-cells or by other cells capable of secreting the protein. Additionally, the IL-10 or active fragments thereof can be chemically synthesized using standard techniques as known in the art. See, e.g., Merrifield, Science 255 : 341 -47 ( 1986) and Atherton et al., Solid Phase Peptide Synthesis, A Practical Approach, 1989, I.R.L. Press, Oxford.

Preferably, the protein or polypeptide is obtained b y recombinant techniques using isolated nucleic acids encoding th e IL-10 polypeptide. General methods of molecular biology are described, e.g., by Sambrook, et al., Molecular Cloning, A Laboratory Manual, Cold Spring Harbor Publish., Cold Spring Harbor, New York, 2d ed. 1989 and by Ausubel et al. (eds.) Current Protocols in Molecular Biology, Green/Wiley, New York ( 1987 and periodic supplements). The appropriate sequences can 4 be obtained using standard techniques from either genomic or cDNA libraries. Polymerase chain reaction (PCR) techniques can be used. See, e.g., PCR Protocols: A Guide to Methods and

Applications, 1990, Innis et al. (Eds.), Academic Press, New York, New York.

Libraries are constructed from nucleic acid extracted from appropriate cells. See, for example, U.S. Patent No. 5 ,231 ,012, which discloses recombinant methods to make IL-10. Useful gene sequences can be found, e.g., in various sequence databases, e.g., Gen Bank and EMBL for nucleic acid, and PIR and Swiss-Prot for protein, c/o Intelligenetics, Mountain View, California; or th e Genetics Computer Group, University of Wisconsin Biotechnology Center, Madison, Wisconsin.

Clones comprising sequences that encode human IL-10 h ave been deposited with the American Type Culture Collection (ATCC), Rockville, Maryland, under Accession Numbers 68191 and 68192. Identification of other clones harboring the sequences encoding IL-10 is performed by either nucleic acid hybridization or immunological detection of the encoded protein, if an expression vector is used. Oligonucleotide probes based on the deposited sequences disclosed in U.S. Patent No. 5,231 ,012 are particularly useful. Oligonucleotide probes useful for identification of th e sequences can also be prepared from conserved regions of related genes in other species. Alternatively, degenerate probes based o n the amino acid sequence of IL-10 can be used.

Standard transfection methods can be used to produce prokaryotic, mammalian, yeast or insect cell lines which express large quantities of the polypeptide. Exemplary E. coli strains suitable for both expression and cloning include W31 10 (ATCC No. 27325), JA221 , C600, ED767, DH1, LE392, HB 101, X1776 (ATCC No. 31244), X2282, RR1 (ATCC No. 31343). Exemplary mammalian cell lines include COS-7 cells, mouse L cells and CHO cells. See

Sambrook (1989) and Ausubel et al. (1987 and supplements).

Various expression vectors can be used to express DNA encoding IL-10. Conventional vectors used for expression of 5 recombinant proteins in prokaryotic or eukaryotic cells may b e used. Preferred vectors include the pcD vectors described b y Okayama et al, Mol. Cell. Biol. 5:280-289 (1983); and Takebe e t al., Mol. Cell. Biol. 8:466-412 ( 1988). Other SV40-based mammalian expression vectors include those disclosed in Kaufman et al., Mol. Cell. Biol. 2 : 1304- 1319 ( 1982) and U.S. Patent No. 4,675,285. These SV40-based vectors are particularly useful in COS-7 monkey cells (ATCC No. CRL 1651), as well as in other mammalian cells such as mouse L cells. See also, Pouwels et al. ( 1989 and supplements) Cloning Vectors: A Laboratory Manual, Elsevier, New York.

The IL- 10 may be produced in soluble form such as a secreted product of transformed or transfected yeast or mammalian cells. The peptides can then be purified by s tandard procedures that are well known in the art. For example, purification steps could include ammonium sulfate precipitation, ion exchange chromatography, gel filtration, electrophoresis, affinity chromatography and the like. See, e.g., Jakoby (ed.), Enzyme Purification and Related Techniques, Methods in Enzymology 22 :233-577 (1977) and Scopes, R., Protein Purification Principles and Practice (Springer- Verlag, New York, 1982).

Alternatively, IL- 10 may be produced in an insoluble form such as aggregates or inclusion bodies. The IL-10 in such a form is then purified by standard procedures that are well known in the art. Examples of purification steps include separating the inclusion bodies from disrupted host cells by centrifugation, solubilizing the inclusion bodies with chaotropic agents an d reducing agents, diluting the solubilized mixture, and lowering th e concentration of chaotropic agent and reducing agent so that th e peptide assumes a biologically active conformation. For specifics of these procedures, see, e.g., Winkler et al., Biochemistry 25:4041 -4045 ( 1986); Winkler et al., Biotechnology 5 : 992-998 ( 1985); Koths et al,. U.S. Patent 4,569,790.

The nucleotide sequences used to transfect the host cells can be modified according to standard techniques to produce th e muteins, variants, truncated analogs and conjugates. 6 Modification of sequences encoding the polypeptides may b e readily accomplished by a variety of techniques, such as site- directed mutagenesis [Gillman et al., Gene S:81 -97 ( 1979); Roberts et al., Nature 328:131 -134 ( 1987)]. Most modifications are evaluated by routine screening in a suitable assay for the desired characteristic. For instance, U.S. Patent No. 5,231 ,012 describes a number of in vitro assays suitable for measuring IL- 10 activity.

Preferably, human IL-10 is used for the treatment of humans, although viral IL-10 or IL-10 from some other mammalian species could be used instead. Most preferably, the IL- 10 used is recombinant human IL-10. The preparation of human IL- 10 has been described in U.S. Patent No. 5,231 ,012. The cloning and expression of a viral IL- 10 (BCRFI protein) from Epstein Bar virus has been disclosed by Moore et al. [Science 248: 1230 ( 1990)].

Individuals suitable for treatment by the methods of this invention include those with major depressive disorder, a s categorized by the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), 4th Ed., Washington, D.C.: American Psychiatric Association, 1994:320-327. Also included in the treatment group are individuals with treatment-resi stant depression, also known as treatment-refractory depression, for whom adequate antidepressant agents had not been available prior to the present invention. See, e.g., Berman et al., Depress. Anxiety 5: 154-164 ( 1997) for a description of such individuals and current therapeutic approaches.

As used herein, the term "effective amount" means a n amount of IL-10 sufficient to alleviate or ameliorate (reduce) one or more of the known symptoms of major depressive disorder. Preferably, a substantial improvement in a score from one or more of the known depression screening instruments, such as th e Beck Depression Inventory [Beck et al., Arch. Gen. Psych. 4 : 561 - 571 (1961 )] or the Hamilton Rating Scale for Depression [British J. Soc. Clin. Psych. 6:278-296 ( 1967)], will be obtained. For a description of these and other such screening instruments, see 7 Schade et al., Psychiatr. Serv. 49:55-61 ( 1998). A substantial improvement in the Hamilton Rating Scale for Depression or in the Beck Depression Inventory, e.g., would be a >50% reduction.

The effective amount of IL-10 administered may range from about 0.01 to about 100 μg per kg of body weight per day . Preferably, the amount will range from about 0.5 to 10 μg of IL- 10 per kg of body weight per day, more preferably from about 1 to 4 μg of IL- 10 per kg of body weight per day. Less frequent administration schedules can also be employed, particularly w hen the IL-10 is in a longer acting form such as a PEG conjugate.

The effective amount for a particular patient will of course vary, depending on factors such as the severity of the maj or depressive disorder being treated, the overall health and age of the patient, the method of administration, the use of additional antidepressant agents, and the severity of any observed side effects .

The duration of IL- 10 administration will depend upon th e particular patient and the severity of his or her condition. I n some cases, treatment for only a relatively short period of time will be required. In other cases, maintenance therapy over a long period of time may be needed.

Generally, IL- 10 is administered as a pharmaceutical composition comprising an effective amount of IL- 10 and a pharmaceutical carrier. A pharmaceutical carrier can be any compatible, non-toxic substance suitable for delivering th e compositions of the invention to a patient.

Administration is typically parenteral by intraperitoneal, intravenous, subcutaneous or intramuscular injection or infusion or by any other acceptable systemic method. Administration b y subcutaneous injection is preferred. Alternatively, the IL- 10 m a y be administered by an implantable or injectable drug delivery system [see, e.g., Urquhart et al., Ann. Rev. Pharmacol. Toxicol. 24: 199 ( 1984); Lewis, Ed., Controlled Release of Pesticides and Pharmaceuticals, 1981 , Plenum Press, New York, New York; U.S. patents Nos. 3,773,919 and 3,270,960] . Administration may also 8 be carried out orally, using well known formulations which protect the IL- 10 from gastrointestinal proteases, or by inhalation. See, e.g., U.S. Patent No. 5,558,085, which discloses and claims methods for intrapulmonary delivery of peptide drugs.

Compositions useful for parenteral administration of such drugs are well known [see, e.g., Remington 's Pharmaceutical Science, 18th Ed. (Mack Publishing Company, Easton, PA 1990)] . When administered parenterally, the IL- 10 is formulated in a unit dosage injectable form (solution, suspension, emulsion) i n association with a pharmaceutical carrier. Examples of such carriers are normal saline, Ringer's solution, dextrose solution, an d Hank's solution. Non-aqueous carriers such as fixed oils and ethyl oleate may also be used. A preferred carrier is 5% dextrose/saline. The carrier may contain minor amounts of additives such as substances that enhance isotonicity and chemical stability, e.g., buffers and preservatives. The IL-10 is preferably formulated in purified form substantially free of aggregates and other source proteins at a concentration in the range of about 5 to 20 μg/ml. Any of the well known carrier proteins such as human serum albumin can also be added if desired.

IL- 10 can also be delivered by standard gene therapy techniques. In one embodiment, cells from a patient afflicted with major depressive disorder, e.g., fibroblasts, are transfected with an expression vector encoding human IL-10. The cells are then re-introduced into the patient, thereby providing a continual supply of the IL- 10. In other embodiments, DNA encoding IL- 1 0 is administered directly to patients.

When the method of treatment to be employed is to introduce a nucleotide sequence encoding IL-10, it is possible to incorporate the naked DNA into a cell. However, when delivering the IL- 10 coding sequence to the target cell, it is preferred th at the DNA be incorporated into a viral or non-viral delivery system.

Examples of non-viral delivery systems used to introduce the IL- 10 gene into the target cell include expression plasmids capable of directing expression of the IL-10 gene in the target cell. 9 Expression plasmids are autonomously replicating, extrachromosomal circular DNA molecules that are distinct from the normal genome and nonessential for cell survival u nder nonselective conditions. Those skilled in the art will readily appreciate the variety of expression plasmids which may be useful in the practice of th e present invention. Promoter, enhancer or other sequences aiding expression of the therapeutic gene and/or IL-10 secretion can also be included in the expression vector. Certain tissue-specific promoters or enhancers enabling preferential expression of the DNA only in particular cell types may also be incorporated. Additional genes, such as those encoding drug resistance, can b e included to allow selection or screening for the presence of th e recombinant vector. Such additional genes can include, e.g., genes encoding neomycin resistance, multi-drug resistance, thymidine kinase, β-galactosidase, dihydrofolate reductase, and chloramphenicol acetyl transferase.

An expression plasmid containing the IL- 10 gene can b e encapsulated in liposomes, which include emulsions, foams, micelles, insoluble monolayers, liquid crystals, phospholipid dispersions, lamellar layers and the like. The delivery of DNA sequences to target cells using liposomal carriers is well known in the art. A variety of methods for preparing liposomes are described, e.g., in Szoka et al., Ann. Rev. Biophys. Bioeng. 9: 461 ( 1980) and in U.S. Patents Nos. 4,394,448; 4,235,871 ;

4,501 ,728; 4,837,028 and 5,019,369.

Liposomes useful in the practice of the present invention may be formed from one or more standard vesicle-forming lipids, which generally include neutral and negatively charged phospholipids and a sterol, such as cholesterol. Examples of such vesicle forming lipids include DC-chol, DOGS, DOTMA, DOPE, DOSPA, DMRIE, DOPC, DOTAP, DORIE, DMRIE-HP. Cationic amphiphiles such as spermidine cholesterol carbamate may also be employed (See, e.g., U.S. Patent No. 5,650,096). The selection of lipids is generally influenced by considerations such as liposome size, and acid lability and stability of the liposomes in the blood stream. 1 0 Although simple liposomal formulations can b e administered, it may be advantageous to incorporate elements that facilitate cellular or tissue targeting into the non-viral delivery system. For example, a lipid encapsulated expression plasmid may incorporate modified surface cell receptor ligands to facilitate targeting. Examples of such ligands include but are not limited to polyclonal antibodies, monoclonal antibodies, humanized antibodies, single chain antibodies, and chimeric antibodies, or functional fragments (e.g., Fv, Fab, Fab') thereof. Alternatively, the gene therapy DNA constructs of the invention can be linked through a polylysine moiety to ligands for a particular cell target of interest, e.g., as described in U.S. Patents Nos. 5.166,320 and 5,635,383. Particularly preferred are ligands that direct preferential delivery of the IL- 10 gene to neuronal cells.

Viral vector delivery systems can also be used, wherein a nucleotide sequence encoding IL-10 is incorporated into a viral genome capable of transfecting a target cell. The IL-10 coding sequence is operably linked to expression control sequences i n these constructs so that the sequence is expressed u nder appropriate conditions in the target cell. Vectors that can b e employed include recombinantly modified enveloped or non- enveloped DNA and RNA viruses, preferably selected from baculoviridiae, parvoviridiae, picornaviridiae, herpesveridiae, poxviridae or adenoviridiae.

Use of the Herpes Simplex Virus (HSV) Type I or Type 2 as a vector is preferred for delivering DNA encoding IL-10 to neuronal cells. The DNA will typically be operably linked to a promoter suitable for controlling expression in neuronal cells, such as the HSV alpha or HSV beta gene promoter.

Chimeric vectors may also be employed which exploit advantageous elements of each of the parent vector properties . See e.g., Feng et al., Nature Biotechnology 75:866-870(1997). Such vectors may be modified by recombinant DNA techniques to include the IL- 10 gene and may be engineered to be replication deficient, conditionally replicating or replication competent. I n 1 1 the preferred practice of the invention, the vectors are replication deficient or conditionally replicating. Preferred vectors are derived from herpes viral or adenoviral genomes.

It may be desirable in some instances to utilize or design vectors to achieve introduction of the IL- 10 gene in a particular cell type. Certain vectors exhibit a natural tropism for certain tissue types. For example, vectors derived from the genus herpesviridiae have been shown to preferentially infect neuronal cells. Examples of recombinantly-modified herpesviridiae vectors are disclosed, e.g., in U.S. Patents Nos. 5,328,688; 5,288,641 ; and 5,599,691 .

In other cases, to insure efficient delivery of the therapeutic gene to a particular tissue or organ, it may be advantageous to incorporate elements into the viral delivery system that facilitate cellular targeting. Viral envelopes used for packaging the constructs of the invention can be modified by the addition of receptor ligands or antibodies specific for a receptor, to permit receptor-mediated endocytosis into specific cells. See, e.g., International Patent Application Publication Nos. WO 93/2022 1 , WO 93/14188; and WO 94/06923.

In some embodiments of the invention, the DNA constructs are linked to viral proteins, such as adenovirus particles, to facilitate endocytosis. See, e.g., Curiel et al., Proc. Natl. Acad. Sci. USA SS:8850-8854 (1991). Cell-type specificity or cell-type targeting may also be achieved in vectors derived from viruses having characteristically broad infectivities, by the modification of the viral envelope proteins.

For example, cell targeting has been achieved with adenovirus vectors by selective modification of the viral genome knob and fiber coding sequences to achieve expression of modified knob and fiber domains having specific interactions with unique cell surface receptors. Examples of such modifications are described, e.g., in Wickham et al, J. Virol 77 : 8221 -8229

(1997) (incorporation of RGD peptides into adenoviral fiber proteins); Arnberg et al, Virology 227:239-244 ( 1997 ) (modification of adenoviral fiber genes to achieve tropism to the 1 2 eye and genital tract); Harris et al, TIG 72 :400-405 ( 1996);

Stevenson et al, J. Virol 77:4782-4790 (1997); Michael et al, Gene

Therapy 2 :660-668 ( 1995) (incorporation of gastrin-releasing peptide fragment into adenovirus fiber protein); and Ohno et al, Nature Biotechnology 15:163-161 ( 1997) (incorporation of Protein

A-IgG binding domain into Sindbis virus).

Other methods of cell-specific targeting have involved conjugation of antibodies or antibody fragments to the envelope proteins. See, e.g., Michael et al, J. Biol. Chem. 2<5S : 6866-6869 (1993); Watkins et al, Gene Therapy 4 : 1004- 1012 ( 1997); Douglas et al, Nature Biotechnology 74: 1574- 1578 (1996). Alternatively, particular moieties may be conjugated to the viral surface to achieve targeting. See, e.g., Nilson et al, Gene Therapy 3 : 280-286 ( 1996) . Conditionally replicating viral vectors may also be employed to achieve selective expression in particular cell types while avoiding untoward broad spectrum infection. Examples of conditionally replicating vectors are described, e.g., in Bischoff e t al, Science 274 :313-316 ( 1996); Pennisi, E., Science 274 : 342-343 (1996); and Russell, S.J., Eur. J. Cancer 30A: \ 165-1 171 ( 1994).

Additionally, the viral genome may be modified to include inducible promoters which achieve replication or expression of th e IL- 10-encoding DNA only under certain conditions. Examples of inducible promoters are well known in the scientific literature. See, e.g., Yoshida et al, Biochem. Biophys. Res. Comm. 230:426-430 (1997); Iida et al, J. Virol. 70:6054-6059 ( 1996); Hwang et al, J. Virol. 77 :7128-7131 ( 1997); Lee et al, Mol. Cell. Biol. 7 7: 5097- 5105 (1997); and Dreher et al, J. Biol. Chem. 272 : 29364-2937 1 (1997). The DNA can also be under the control of a tissue-specific promoter region, allowing expression of the DNA only in particular cell types.

In some instances, particularly when employing a conditionally replicating or replication competent vector, it may be desirable to include a suicide gene in the viral vector in addition to the IL- 10 gene. A suicide gene is a nucleic acid sequence, th e expression of which renders the cell susceptible to killing b y 1 3 external factors or causes a toxic condition in the cell. A well known example of a suicide gene is the thymidine kinase

(TK) gene, through the use of which cells expressing the TK gene product are susceptible to selective killing by the administration of gancyclovir. See, e.g., U.S. Patent Nos. 5 ,63 1 ,236 and 5,601 ,818. This provides a "safety valve" for the viral vector delivery system to prevent widespread infection, in the event of spontaneous generation of replication-competent viral vectors. Of course, other modifications can be made to the viral vectors to achieve particular expression characteristics, or to permit repeat administration or to lower immune responses against the vectors.

IL-10 can be administered alone or in combination with one or more of the other agents or methods commonly used to treat or ameliorate the symptoms of major depressive disorder. Antidepressant agents that can be co-administered with the IL- 10 include but are not limited to amitriptyline, clomipramine, doxepine, imipramine, trimipramine, amoxapine, desipramine, nortriptyline, proptriptyline, bupropion, maprotiline, mirtazapine, nefazodone, trazodone, venlafaxine, fluoxetine, fluvoxamine, paroxetine, sertraline, phenelzine, tranylcypromine, an d moclobemide.

Because of the antidepressant activity of the IL-10, it m ay be that the other antidepressant drugs can be administered i n lower than typical amounts, thereby reducing the serious side- effects often associated with the use of such drugs. The IL-10 can also be administered in combination with lithium o r electroconvulsive therapy, and in conjunction with s tandard psychotherapy .

Co-administration of one or more other antidepressant agents can be concomitant (together with administration of the IL- 10) or sequential (before or after administration of the IL-10). All of the administered agents should be present in the patient a t sufficient levels to be therapeutically effective. Typically, if a second agent is administered within about the half-life of the first agent, the two agents are considered to be co-administered. 1 4 EXAMPLE

The following non-limiting Example will serve to illustrate the present invention.

In a clinical study of the effect of IL-10 in the treatment of Crohn' s disease, patients were randomized to receive recombinant human IL- 10 doses of 0 (placebo), 1 , 4, 8 or 20 μg/kg once daily

(QD) for four weeks by subcutaneous administration. Each treatment group comprised about 65 patients.

To assess the effects of IL-10 on mood state, patients in each treatment group were initially divided into two groups on th e basis of pretreatment mental health (MH) scores. The MH scores were based on responses to five self-rating items (items 9 b, c, d, f and h) relating to mental state from the SF-36 questionnaire [Ware JE Jr., ed., SF-36 Health Survey: Manual and Interpretation Guide, 1993, Nimrod Press, Boston, MA], which assesses a n individual' s physical and mental condition.

The response categories for the five mental health questions are based upon a six-point scale, ranging from 1 (mental state experienced "all of the time") to 6 (mental state experienced "none of the time"). The sum of the raw scores for the five MH questions thus could range from 5 to 30. To obtain the data described below, the actual raw scores provided by the patients w ere transformed to a scale of from 0 to 100, as described in the SF-36 Manual and Interpretation Guide (Ware, supra) .

1 5 An MH score of <40 is consistent with a diagnosis of depression ("depressed"), whereas an MH score of >40 suggests a n absence of depression ("nondepressed"). By these criteria, about one-third of the patients in each treatment group were found to be depressed at the time of randomization.

The depressed patients developed substantial increases in MH scores (i.e., improvement, or antidepressant responses) following treatment with IL- 10 doses of 1 , 4 or 8 μg/kg QD for four weeks, but not with placebo or with 20 μg/kg QD doses. No significant changes in MH scores occurred in the patients initially categorized as nondepressed after any dose of IL-10 or placebo. The results are shown in Fig. 1 , in which the changes in MH scores are the scores at the end of treatment minus the baseline (at time of randomization) scores. Greater changes in MH scores reflect improvement.

The differences in MH responses at the 1 , 4 and 8 μg/kg dose levels between depressed and nondepressed patients were not due to differences in Crohn's disease activity index [CDAI; Best et al, G astro enter ology 70:439-444 ( 1976)] scores at baseline (Fig. 2) or in the adjusted CDAI responses to treatment (Fig. 3). The changes in CDAI scores shown in Fig. 3 are the scores at the end of treatment minus the baseline scores. Greater decreases in CDAI scores represent improvement. In all of the Figures, the placebo is shown as a 0 μg/kg dose of IL- 10.

The independence of changes in MH scores and changes i n

CDAI scores was also confirmed by lack of statistically significant correlations between these variables.

Thus, the relief from depression observed following the treatment with IL- 10 was essentially independent of the severity of the underlying Crohn's disease and was not attributable to improved mental state resulting from alleviation of the disease.

Many modifications and variations of this invention can b e made without departing from its spirit and scope, as will become apparent to those skilled in the art. The specific embodiments 1 6 described herein are offered by way of example only, and the invention is to be limited only by the terms of the appended claims.

Claims

1 7 WHAT IS CLAIMED IS:

1. A method for treating major depressive disorder comprising administering a depression-alleviating amount of IL- 10 to an individual afflicted with major depressive disorder.

2. The method of claim 1 in which the IL- 10 is recombinant human IL- 10.

3. The method of claim 1 in which the IL-10 is administered by subcutaneous injection.

4. The method of claim 1 in which the IL-10 is administered in a daily dosage range of from about 0.5 to about 10 ╬╝g/kg body weight.

5. The method of claim 4 in which the IL-10 is administered in a daily dosage range of from about 1 to about 4 ╬╝g/kg body weight.

6. The method of claim 1 which further comprises administering electroconvulsive therapy to said individual.

7. The method of claim 1 which further comprises co-administering one or more other antidepressant agents to said individual.

8. The method of claim 7 in which the antidepressant agent is amitriptyline, clomipramine, doxepine, imipramine, trimipramine, amoxapine, desipramine, nortriptyline, proptriptyline, bupropion, maprotiline, mirtazapine, nefazodone, trazodone, venlafaxine, fluoxetine, fluvoxamine, paroxetine, sertraline, phenelzine, tranylcypromine, or moclobemide.

9. The method of claim 7 in which the IL-10 is recombinant human IL- 10.

10. The method of claim 7 in which the IL-10 is administered by subcutaneous injection. 1 8

11. The method of claim 7 in which the IL- 10 is administered in a daily dosage range of from about 0.5 to about 10 ╬╝g/kg body weight.

12. The method of claim 1 1 in which the IL- 10 is administered in a daily dosage range of from about 1 to about 4 ╬╝g/kg body weight.

13. The method of claim 1 in which the individual is afflicted with treatment-resistant depression.

14. The method of claim 7 in which the individual is afflicted with treatment-resistant depression.