WO2012056232A1 - Biomarkers - Google Patents

Abstract

The invention relates to a method of diagnosing or monitoring schizophrenia or other psychotic disorder.

Description

BIOMARKERS

FIELD OF THE INVENTION

The invention relates to a method of diagnosing or monitoring schizophrenia or other psychotic disorder.

BACKGROUND OF THE INVENTION

Schizophrenia is a psychiatric diagnosis that describes a mental disorder characterized by abnormalities in the perception or expression of reality. It most commonly manifests as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking with significant social or occupational dysfunction. Onset of symptoms typically occurs in young adulthood, with approximately 0.4-0.6% of the population affected. Diagnosis is based on the patient's self-reported experiences and observed behavior. No laboratory test for schizophrenia currently exists.

Studies suggest that genetics, early environment, neurobiology, psychological and social processes are important contributory factors; some recreational and prescription drugs appear to cause or worsen symptoms. Current psychiatric research is focused on the role of neurobiology, but no single organic cause has been found. Due to the many possible combinations of symptoms, there is debate about whether the diagnosis represents a single disorder or a number of discrete syndromes. The disorder is thought to mainly affect cognition, but it also usually contributes to chronic problems with behavior and emotion. People with schizophrenia are likely to have additional (comorbid) conditions, including major depression and anxiety disorders; the lifetime occurrence of substance abuse is around 40%. Social problems, such as long-term unemployment, poverty and homelessness, are common. Furthermore, the average life expectancy of people with the disorder is 10 to 12 years less than those without, due to increased physical health problems and a higher suicide rate. An important utility of biomarkers for psychotic disorders is their response to medication. Administration of antipsychotics remains a subjective process, relying solely on the experience of clinicians. Furthermore, the development of antipsychotic drugs has been based on chance findings often with little relation to the background driving the observations.

Schizophrenia is treated primarily with antipsychotic medications which are also referred to as neuroleptic drugs or neuroleptics. Newer antipsychotic agents such as clozapine, olanzapine, quetiapine or risperidone are thought to be more effective in improving negative symptoms of psychotic disorders than older medication like Chlorpromazine. Furthermore, they induce less extrapyramidal side effects (EPS) which are movement disorders resulting from antipsychotic treatment. The history of neuroleptics dates back to the late 19th century. The flourishing dye industry catalyzed development of new chemicals that lay the background to modern day atypical antipsychotics. Developments in anti-malaria, antihistamine and anaesthetic compounds also produced various neuroleptics. The common phenomenon to all these processes is a fundamental lack of

understanding of the biological mechanisms and pathways that these drugs affect, apart from the observation that they prominently block D2 receptors in the striatum.

There is therefore a pressing need for objective molecular readouts that can diagnose schizophrenia or other psychotic disorders and furthermore indicate whether a patient is responding to medication, as well as for predicting

prognosis.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided the use of Apolipoprotein C-II (APOC2) as a biomarker for schizophrenia or other psychotic disorder, or predisposition thereto. According to a second aspect of the invention, there is provided the use of two or more analytes selected from Apolipoprotein C-II (APOC2), Lumican,

Apolipoprotein B-100 (ApoB) and Fetuin-B (FETUB) as a biomarker for

schizophrenia or other psychotic disorder, or predisposition thereto.

According to a third aspect of the invention, there is provided a method of diagnosing or monitoring schizophrenia or other psychotic disorder, or predisposition thereto, comprising detecting and/or quantifying, in a sample from a test subject, the analyte biomarkers defined herein.

According to a fourth aspect of the invention, there is provided a method of diagnosing schizophrenia or other psychotic disorder, or predisposition in an individual thereto, comprising :

(a) quantifying the amounts of the analyte biomarkers as defined herein in a biological sample obtained from an individual;

(b) comparing the amounts of the analyte biomarkers in the biological sample with the amounts present in a normal control biological sample from a normal subject, such that a difference in the level of the analyte biomarkers in the biological sample is indicative of schizophrenia or other psychotic disorder, or predisposition thereto.

According to a fifth aspect of the invention, there is provided a method of monitoring efficacy of a therapy in a subject having, suspected of having, or of being predisposed to schizophrenia or other psychotic disorder, comprising detecting and/or quantifying, in a sample from said subject, the analyte biomarkers defined herein.

According to a sixth aspect of the invention, there is provided a method of determining the efficacy of therapy for schizophrenia or other psychotic disorder in an individual subject comprising :

(a) quantifying the amounts of the analyte biomarkers as defined herein in a biological sample obtained from an individual;

(b) comparing the amounts of the analyte biomarkers in the biological sample with the amounts present in a sample obtained from the individual on a previous occasion, such that a difference in the level of the analyte biomarkers in the biological sample is indicative of a beneficial effect of the therapy.

A further aspect of the invention provides ligands, such as naturally occurring or chemically synthesised compounds, capable of specific binding to the peptide biomarker. A ligand according to the invention may comprise a peptide, an antibody or a fragment thereof, or an aptamer or oligonucleotide, capable of specific binding to the peptide biomarker. The antibody can be a monoclonal antibody or a fragment thereof capable of specific binding to the peptide biomarker. A ligand according to the invention may be labelled with a detectable marker, such as a luminescent, fluorescent or radioactive marker; alternatively or additionally a ligand according to the invention may be labelled with an affinity tag, e.g . a biotin, avidin, streptavidin or His (e.g . hexa-His) tag . A biosensor according to the invention may comprise the peptide biomarker or a structural/shape mimic thereof capable of specific binding to an antibody against the peptide biomarker. Also provided is an array comprising a ligand or mimic as described herein. Also provided by the invention is the use of one or more ligands as described herein, which may be naturally occurring or chemically synthesised, and is suitably a peptide, antibody or fragment thereof, aptamer or oligonucleotide, or the use of a biosensor of the invention, or an array of the invention, or a kit of the invention to detect and/or quantify the peptide. In these uses, the detection and/or quantification can be performed on a biological sample such as from the group consisting of CSF, whole blood, blood serum, plasma, urine, saliva, or other bodily fluid, breath, e.g . as condensed breath, or an extract or purification therefrom, or dilution thereof. Diagnostic or monitoring kits are provided for performing methods of the invention. Such kits will suitably comprise a ligand according to the invention, for detection and/or quantification of the peptide biomarker, and/or a biosensor, and/or an array as described herein, optionally together with instructions for use of the kit. A further aspect of the invention is a kit for monitoring or diagnosing schizophrenia or other psychotic disorder, comprising a biosensor capable of detecting and/or quantifying the analyte biomarkers as defined herein.

Biomarkers for schizophrenia or other psychotic disorder are essential targets for discovery of novel targets and drug molecules that retard or halt progression of the disorder. As the level of the peptide biomarker is indicative of disorder and of drug response, the biomarker is useful for identification of novel therapeutic compounds in in vitro and/or in vivo assays. Biomarkers of the invention can be employed in methods for screening for compounds that modulate the activity of the peptide.

Thus, in a further aspect of the invention, there is provided the use of a ligand, as described, which can be a peptide, antibody or fragment thereof or aptamer or oligonucleotide according to the invention; or the use of a biosensor according to the invention, or an array according to the invention; or a kit according to the invention, to identify a substance capable of promoting and/or of suppressing the generation of the biomarker.

Also there is provided a method of identifying a substance capable of promoting or suppressing the generation of the peptide in a subject, comprising administering a test substance to a subject animal and detecting and/or quantifying the level of the peptide biomarker present in a test sample from the subject.

DETAILED DESCRIPTION OF THE INVENTION

According to a first aspect of the invention, there is provided the use of Apolipoprotein C-II (APOC2) as a biomarker for schizophrenia or other psychotic disorder, or predisposition thereto.

Data is provided herein which demonstrates that APOC2 is a statistically significant biomarker for the diagnosis of schizophrenia after treatment with olanzapine, risperidone, quetiapine or a mixture thereof and APOC2 was additionally found to be statistically significant in samples obtained from two completely separate clinical centres. Furthermore, an additional validation study conducted with APOC2 demonstrated that increased levels of APOC2 were observed in serum following a 4 week treatment with either risperidone/quetiapine or olanzapine (see Table 2 and Figure 1).

According to a second aspect of the invention, there is provided the use of two or more analytes selected from Apolipoprotein C-II (APOC2), Lumican,

Apolipoprotein B-100 (ApoB) and Fetuin-B (FETUB) as a biomarker for

schizophrenia or other psychotic disorder, or predisposition thereto.

Data is provided herein which demonstrates that the four analytes of the second aspect of the invention are statistically significant biomarkers for the diagnosis of schizophrenia after treatment with olanzapine, risperidone, quetiapine or a mixture thereof and each of the four analytes of the second aspect of the invention were additionally found to be statistically significant in samples obtained from two completely separate clinical centres.

In one embodiment of the second aspect of the invention, the analyte is Apolipoprotein C-II (APOC2).

In one embodiment of the first or second aspects of the invention, the use additionally comprises one or more further analytes selected from Lumican, Apolipoprotein B-100 (ApoB) and Fetuin-B (FETUB).

According to a further aspect of the invention, there is provided the use of Apolipoprotein C-II (APOC2), Lumican, Apolipoprotein B-100 (ApoB) and Fetuin- B (FETUB) as a specific panel of analyte biomarkers for schizophrenia or other psychotic disorder, or predisposition thereto.

In one embodiment of any of the aforementioned aspects of the invention, the use additionally comprises one or more further analytes selected from

Phospholipid transfer protein, Cartilage oligomeric matrix protein, Keratin type II cytoskeletal 5 (KRT5), Zinc finger protein 57 (ZFP57), C-type mannose receptor 2 (MRC2), Beta-Ala-His dipeptidase (CNDPl), Mitogen-activated protein kinase 2 (M4K2), Apolipoprotein C-I, Attractin, Hemoglobin subunit epsilon (HBE), Ankyrin repeat domain-containing protein 58 (ANR58), Actin, aortic smooth muscle (ACTA), EGF-containing fibulin-like extracellular matrix protein 1

(FBLN3), Dual specificity protein phosphatase CDC14B (CC14B), Nesprin-3 (SYNE3), Complement Clr subcomponent, Protein MCM 10 homolog (MCM10), Putative zinc-alpha-2-glycoprotein-like 1, Ceruloplasmin, Leucine-rich alpha-2- glycoprotein (A2GL), Elongation factor 1-gamma (EF1G), Ig gamma-1 chain C region (IGHG1), Insulin-like growth factor-binding protein 3 (IGFBP3), N- acetylated-alpha-linked acidic dipeptidase 2 (NALD2), Uncharacterized protein C9orf75 (CI075), Protein FAM83D (FA83D), Cytoplasmic aconitate hydratase, BTB/POZ domain-containing protein KCTD17, WD repeat-containing protein 23 (WDR23), Zinc finger protein 287 (ZN287), Mannan-binding lectin serine protease 1 (MASP1), Thrombospondin-2 (TSP-2), Ras-related protein Rab-18 (RAB18), Protein FAM98C (FA98C), Zinc-alpha-2-glycoprotein, Ig lambda chain V-II region VIL, Carboxypeptidase N subunit 2 (CPN2), Polyadenylate-binding protein 4 (PABP4), Septin-13 (SEP13), Zinc finger protein 189 (ZN189), Leucine- rich glioma-inactivated protein 1 (LGI1), Uncharacterized protein KIAA0552 (K0552), Transthyretin, Inter-alpha-trypsin inhibitor heavy chain H I (ITIH l), Ig mu heavy chain, Ubiquilin-3 (UBQL3), Serine/threonine-protein kinase PDIK1 L, Complement C2 (C02), T-cell surface glycoprotein CDlb (CD1B), Vitamin D- binding protein (VTDB), Thrombospondin-4 (TSP4), Beta-1,4- galactosyltransferase 3 (B4GT3), 60S ribosomal export protein NMD3,

Complement factor H (CFAH), Structural maintenance of chromosomes protein 4 (SMC4), Kinesin-like protein KIF16B (KI16B), Myelin protein PO (MYPO),

Forkhead box protein P3 (FOXP3), NACHT, LRR and PYD domains-containing protein 14, Apolipoprotein A-IV, Protein CLN8, Apolipoprotein C-III, Proteasome subunit alpha type-2 (PSA2), Glycosyltransferase-like protein LARGE1 (LARGE), Collagen alpha-l(XXII) chain (COMA1), Sulfhydryl oxidase 1 (QSOX1), RING finger protein 214 (RN214), Alpha-2-HS-glycoprotein, Plasma protease CI inhibitor (IC1), Apolipoprotein (a), Properdin (PROP), Complement factor H- related protein 1 (FHR1), Apolipoprotein C-I, Apolipoprotein E, Platelet basic protein (CXCL7), Paxillin (PAXI), Angiotensinogen, Clusterin, Complement component C8 beta chain (C08B), Pigment epithelium-derived factor (PEDF), CD5 antigen-like (CD5L), Complement Clr subcomponent (CIR), Keratin, type I cytoskeletal 10 (K1C10), Biotinidase (BTD), Apolipoprotein M, Pregnancy zone protein (PZP), F-box only protein 11 (FBX11. FBXOl l), AP20 region protein 1 (APRG1), Gelsolin (GELS), Cold shock domain-containing protein El (CSDE1), KH domain-containing, RNA-binding, signal transduction-associated protein 1 (KHDRl), Keratin, type I cytoskeletal 26 (K1C26), Ig mu chain C region (IGHM), Complement component C7 (C07) and Synaptophysin-like protein 1 (SYPL1).

Data is provided herein which demonstrates that these analyte biomarkers were statistically significant biomarkers for the diagnosis of schizophrenia after treatment with olanzapine, risperidone, quetiapine or a mixture thereof across both clinical centres studied.

According to a further aspect of the invention, there is provided the use of Apolipoprotein C-II, Lumican, Apolipoprotein B-100, Fetuin-B, Phospholipid transfer protein, Cartilage oligomeric matrix protein, Keratin type II cytoskeletal 5, Zinc finger protein 57, C-type mannose receptor 2, Beta-Ala-His dipeptidase, Mitogen-activated protein kinase 2, Apolipoprotein C-I, Attractin, Hemoglobin subunit epsilon, Ankyrin repeat domain-containing protein 58, Actin aortic smooth muscle, EGF-containing fibul in- 1 ike extracellular matrix protein 1, Dual specificity protein phosphatase CDC14B, Nesprin-3, Complement Clr

subcomponent, Protein MCM 10 homolog, Putative zinc-alpha-2-glycoprotein-like 1, Ceruloplasmin, Leucine-rich alpha-2-glycoprotein, Elongation factor 1-gamma, Ig gamma-1 chain C region, Insulin-like growth factor-binding protein 3, N- acetylated-alpha-linked acidic dipeptidase 2, Uncharacterized protein C9orf75, Protein FAM83D, Cytoplasmic aconitate hydratase, BTB/POZ domain-containing protein KCTD17, WD repeat-containing protein 23, Zinc finger protein 287, Mannan-binding lectin serine protease 1, Thrombospondin-2, Ras-related protein Rab-18, Protein FAM98C, DNA-directed RNA polymerase I subunit RPA1, Zinc- alpha-2-glycoprotein, Ig lambda chain V-II region VIL, Carboxypeptidase N subunit 2, Polyadenylate-binding protein 4, Septin-13, Zinc finger protein 189, Leucine-rich glioma-inactivated protein 1, Uncharacterized protein KIAA0552, Transthyretin, Inter-alpha-trypsin inhibitor heavy chain HI, Ig mu heavy chain, Ubiquilin-3, Serine/threonine-protein kinase PDIK1L, Complement C2, T-cell surface glycoprotein CDlb and Vitamin D-binding protein as a specific panel of analyte biomarkers for schizophrenia or other psychotic disorder, or predisposition thereto.

Data is provided herein which demonstrates that this specific panel of analyte biomarkers were statistically significant biomarkers for the diagnosis of schizophrenia after treatment with olanzapine, risperidone, quetiapine or a mixture thereof in samples obtained from clinical centre 1.

In one embodiment of any of the aforementioned aspects of the invention, the analyte biomarkers are selected from : Apolipoprotein C-II, Lumican,

Apolipoprotein B-100, Fetuin-B, Phospholipid transfer protein, Cartilage oligomeric matrix protein, Keratin type II cytoskeletal 5, Zinc finger protein 57, C-type mannose receptor 2, Beta-Ala-His dipeptidase, Mitogen-activated protein kinase 2, Apolipoprotein C-I, Attractin, Hemoglobin subunit epsilon, Ankyrin repeat domain-containing protein 58, Actin aortic smooth muscle, EGF- containing fibulin-like extracellular matrix protein 1, Dual specificity protein phosphatase CDC14B, Nesprin-3, Complement Clr subcomponent, Protein MCM10 homolog, Putative zinc-alpha-2-glycoprotein-like 1, Ceruloplasmin, Leucine-rich alpha-2-glycoprotein, Elongation factor 1-gamma, Ig gamma-1 chain C region, Insulin-like growth factor-binding protein 3, N-acetylated-alpha- linked acidic dipeptidase 2, Uncharacterized protein C9orf75, Protein FAM83D, Cytoplasmic aconitate hydratase, BTB/POZ domain-containing protein KCTD17, WD repeat-containing protein 23, Zinc finger protein 287, Mannan-binding lectin serine protease 1, Thrombospondin-2, Ras-related protein Rab-18, Protein FAM98C, DNA-directed RNA polymerase I subunit RPA1, Ig lambda chain V-II region VIL, Polyadenylate-binding protein 4, Septin-13, Zinc finger protein 189, Leucine-rich glioma-inactivated protein 1, Uncharacterized protein KIAA0552, Transthyretin, Ig mu heavy chain, Ubiquilin-3, Complement C2, T-cell surface glycoprotein CDlb and Vitamin D-binding protein.

Data is provided herein which demonstrates that levels of these analyte biomarkers were statistically increased following treatment with olanzapine, risperidone, quetiapine or a mixture thereof in samples obtained from clinical centre 1.

In one embodiment of any of the aforementioned aspects of the invention, the analyte biomarkers are selected from : Zinc-alpha-2-glycoprotein,

Carboxypeptidase N subunit 2, Inter-alpha-trypsin inhibitor heavy chain H I and Serine/threonine-protein kinase PDIK1 L

Data is provided herein which demonstrates that levels of these analyte biomarkers were statistically decreased following treatment with olanzapine, risperidone, quetiapine or a mixture thereof in samples obtained from clinical centre 1.

According to a further aspect of the invention, there is provided the use of Apolipoprotein C-II, Lumican, Apolipoprotein B-100, Fetuin-B, Thrombospondin- 4, EGF-containing fibulin-like extracellular matrix protein 1, Beta-1,4- galactosyltransferase 3, 60S ribosomal export protein NMD3, Complement factor H, Structural maintenance of chromosomes protein 4, Kinesin-like protein KIF16B, Myelin protein PO, Forkhead box protein P3, NACHT LRR and PYD domains-containing protein 14, Apolipoprotein A-IV, Protein CLN8,

Apolipoprotein C-III, Proteasome subunit alpha type-2, Glycosyltransferase-like protein LARGEl, Collagen alpha-l(XXII) chain, Sulfhydryl oxidase 1, RING finger protein 214, Alpha-2-HS-glycoprotein, Plasma protease CI inhibitor,

Apolipoprotein(a), Properdin, Complement factor H-related protein 1,

Apolipoprotein C-I, Apolipoprotein E, Platelet basic protein, Paxillin,

Angiotensinogen, Clusterin, Complement component C8 beta chain, Pigment epithelium-derived factor, CD5 antigen-like, Complement Clr subcomponent, Keratin type I cytoskeletal 10, Biotinidase, Apolipoprotein M, Pregnancy zone protein, F-box only protein 11, AP20 region protein 1, Gelsolin, Cold shock domain-containing protein El, KH domain-containing RNA-binding signal transduction-associated protein 1, Keratin type I cytoskeletal 26, Ig mu chain C region, Complement component C7 and Synaptophysin-like protein 1 as a specific panel of analyte biomarkers for schizophrenia or other psychotic disorder, or predisposition thereto. Data is provided herein which demonstrates that this specific panel of analyte biomarkers were statistically significant biomarkers for the diagnosis of schizophrenia after treatment with olanzapine, risperidone, quetiapine or a mixture thereof in samples obtained from clinical centre 2.

In one embodiment of any of the aforementioned aspects of the invention, the analyte biomarkers are selected from : Apolipoprotein C-II, Lumican,

Apolipoprotein B-100, Fetuin-B, Thrombospondin-4, EGF-containing fibulin-like extracellular matrix protein 1, Beta-l,4-galactosyltransferase 3, 60S ribosomal export protein NMD3, Complement factor H, Structural maintenance of

chromosomes protein 4, Kinesin-like protein KIF16B, Myelin protein PO,

Forkhead box protein P3, NACHT LRR and PYD domains-containing protein 14, Apolipoprotein A-IV, Protein CLN8, Apolipoprotein C-III, Proteasome subunit alpha type-2, Glycosyltransferase-like protein LARGE1, Collagen alpha-l(XXII) chain, Sulfhydryl oxidase 1, RING finger protein 214, Alpha-2-HS-glycoprotein, Apolipoprotein(a), Properdin, Complement factor H-related protein 1,

Apolipoprotein C-I, Apolipoprotein E, Paxillin, Clusterin, Pigment epithelium- derived factor, CD5 antigen-like, Complement Clr subcomponent, Keratin type I cytoskeletal 10, Biotinidase, Apolipoprotein M, Pregnancy zone protein, F-box only protein 11, AP20 region protein 1, Gelsolin, Cold shock domain-containing protein El, KH domain-containing RNA-binding signal transduction-associated protein 1, Keratin type I cytoskeletal 26 and Ig mu chain C region. Data is provided herein which demonstrates that levels of these analyte biomarkers were statistically increased following treatment with olanzapine, risperidone, quetiapine or a mixture thereof in samples obtained from clinical centre 2. In one embodiment of any of the aforementioned aspects of the invention, the analyte biomarkers are selected from : Plasma protease CI inhibitor, Platelet basic protein, Angiotensinogen, Complement component C8 beta chain, Complement component C7 and Synaptophysin-like protein 1. Data is provided herein which demonstrates that levels of these analyte biomarkers were statistically decreased following treatment with olanzapine, risperidone, quetiapine or a mixture thereof in samples obtained from clinical centre 2.

According to a further aspect of the invention there is provided the use of one or more first analyte biomarkers selected from : Apolipoprotein C-II (APOC2), Keratin type II cytoskeletal 5 (KRT5), Zinc finger protein 57 (ZFP57), C-type mannose receptor 2 (MRC2), Beta-Ala-His dipeptidase (CNDP1), Mitogen- activated protein kinase 2 (M4K2), Hemoglobin subunit epsilon (HBE), Ankyrin repeat domain-containing protein 58 (ANR58), EGF-containing fibulin-like extracellular matrix protein 1 (FBLN3), Dual specificity protein phosphatase CDC14B (CC14B), Nesprin-3 (SYNE3), Protein MCM 10 homolog (MCM 10), Leucine-rich alpha-2-glycoprotein (A2GL), Elongation factor 1-gamma (EF1G), Uncharacterized protein C9orf75 (CI075), Protein FAM83D (FA83D), BTB/POZ domain-containing protein KCTD17, Zinc finger protein 287 (ZN287), Mannan- binding lectin serine protease 1 (MASP1), Thrombospondin-2 (TSP-2), Protein FAM98C (FA98C), Ig lambda chain V-II region VIL, Carboxypeptidase N subunit 2 (CPN2), Polyadenylate-binding protein 4 (PABP4), Septin-13 (SEP13), Zinc finger protein 189 (ZN189), Uncharacterized protein KIAA0552 (K0552), Inter- alpha-trypsin inhibitor heavy chain HI (ITIH 1), Complement C2 (C02), T-cell surface glycoprotein CDlb (CD1B), Vitamin D-binding protein (VTDB),

Thrombospondin-4 (TSP4), Beta-l,4-galactosyltransferase 3 (B4GT3), 60S ribosomal export protein NMD3, Complement factor H (CFAH), Structural maintenance of chromosomes protein 4 (SMC4), Myelin protein PO (MYPO), Forkhead box protein P3 (FOXP3), NACHT, LRR and PYD domains-containing protein 14, Protein CLN8, Apolipoprotein C-III, Glycosyltransferase-like protein LARGE1 (LARGE), Collagen alpha-l(XXII) chain (COMA1), Sulfhydryl oxidase 1 (QSOXl), RING finger protein 214 (RN214), Plasma protease CI inhibitor (ICl), Properdin (PROP), Platelet basic protein (CXCL7), Paxillin (PAXI), Complement component C8 beta chain (C08B), Pigment epithelium-derived factor (PEDF), Keratin, type I cytoskeletal 10 (K1C10), Biotinidase (BTD), AP20 region protein 1 (APRG1), Cold shock domain-containing protein El (CSDE1), KH domain- containing, RNA-binding, signal transduction-associated protein 1 (KHDR1), Keratin, type I cytoskeletal 26 (K1C26), Ig mu chain C region (IGHM) and

Synaptophysin-like protein 1 (SYPL1) as a biomarker for schizophrenia or other psychotic disorder, or predisposition thereto. According to a further aspect of the invention there is provided the use of two or more second analyte biomarkers selected from : Lumican, Apolipoprotein B-100 (ApoB), Fetuin-B (FETUB), Phospholipid transfer protein, Cartilage oligomeric matrix protein, Apolipoprotein C-I, Attractin, Actin, aortic smooth muscle

(ACTA), Complement Clr subcomponent, Putative zinc-alpha-2-glycoprotein-like 1, Ceruloplasmin, Ig gamma-1 chain C region (IGHG1), Insulin-like growth factor-binding protein 3 (IGFBP3), N-acetylated-alpha-linked acidic dipeptidase 2 (NALD2), Cytoplasmic aconitate hydratase, WD repeat-containing protein 23 (WDR23), Zinc-alpha-2-glycoprotein, Leucine-rich glioma-inactivated protein 1 (LGI1), Transthyretin, Ig mu heavy chain, Ubiquilin-3 (UBQL3),

Serine/threonine-protein kinase PDIK1L, Kinesin-like protein KIF16B (KI16B), Apolipoprotein A-IV, Proteasome subunit alpha type-2 (PSA2), Alpha-2-HS- glycoprotein, Apolipoprotein (a), Complement factor H-related protein 1 (FHR1), Apolipoprotein C-I, Apolipoprotein E, Angiotensinogen, Clusterin, CD5 antigenlike (CD5L), Complement Clr subcomponent (C1R), Apolipoprotein M, Pregnancy zone protein (PZP), F-box only protein 11 (FBX11. FBXOl l), Gelsolin (GELS), Ras-related protein Rab-18 (RAB18) and Complement component C7 (C07) as a biomarker for schizophrenia or other psychotic disorder, or predisposition thereto. According to a further aspect of the invention, there is provided a method for classifying a psychotic patient, such as a schizophrenia patient, as a responder or non-responder to antipsychotic therapy, such as schizophrenia therapy, comprising the steps of:

(a) quantifying the amounts of the analyte biomarkers as defined herein in a test biological sample obtained from the patient; and

(b) classifying the patient as a responder or non-responder to anti psychotic therapy based on the expression levels of the analyte biomarkers. Data is provided herein which was obtained from a study which comprised the use of serum samples collected from first onset schizophrenia patients at two time points. The first time point was prior to treatment with antipsychotic (AS) medication. The second time point was from the same patients after treatment with either a specific AS medication or a combination of drugs. The results provided were obtained from patients which responded well to treatment (based on clinical observation by the psychiatrists). Surprisingly, the concentration of each of the analyte biomarkers of the invention changes after treatment.

Therefore, the data presented herein provides the applicability of the analyte biomarkers of the invention to predict which patients would respond well to antipsychotic treatment, based on a molecular signature rather than a subjective clinical assessment.

According to a further aspect of the invention, there is provided a method for monitoring patient compliance with antipsychotic therapy, such as schizophrenia therapy, comprising the steps of:

(a) quantifying the amounts of the analyte biomarkers as defined herein in a test biological sample obtained from the patient prior to commencement of antipsychotic therapy; and

(b) comparing the amounts of the analyte biomarkers in the biological sample with the amounts present in a biological sample obtained from the patient after commencement of antipsychotic therapy, such that a difference in the level of the analyte biomarkers in the biological sample is indicative of patient compliance with antipsychotic therapy.

As discussed hereinbefore, surprisingly, the concentration of each of the analyte biomarkers of the invention changes after treatment. Therefore, the data presented herein provides the applicability of the analyte biomarkers of the invention to monitor whether patients comply with the prescribed antipsychotic treatment. Patient compliance is a particular problem with antipsychotic disorders because a significant number of patients do not comply with the prescription or required dosage regime. The term "biomarker" means a distinctive biological or biologically derived indicator of a process, event, or condition. Peptide biomarkers can be used in methods of diagnosis, e.g . clinical screening, and prognosis assessment and in monitoring the results of therapy, identifying patients most likely to respond to a particular therapeutic treatment, drug screening and development. Biomarkers and uses thereof are valuable for identification of new drug treatments and for discovery of new targets for drug treatment.

As used herein, the term "biosensor" means anything capable of detecting the presence of the biomarker. Examples of biosensors are described herein.

References herein to "other psychotic disorder" relate to any appropriate psychotic disorder according to DSM-IV Diagnostic and Statistical Manual of Mental Disorders, 4th edition, American Psychiatric Assoc, Washington, D.C., 2000. In one particular embodiment, the other psychotic disorder is a psychotic disorder related to schizophrenia. Examples of psychotic disorders related to schizophrenia include brief psychotic disorder delusional disorder, psychotic disorder due to a general medical condition, schizoeffective disorder, schizophreniform disorder, and substance-induced psychotic disorder.

In one embodiment, one or more of the biomarkers defined hereinbefore may be replaced by a molecule, or a measurable fragment of the molecule, found upstream or downstream of the biomarker in a biological pathway. Biosensors according to the invention may comprise a ligand or ligands, as described herein, capable of specific binding to the peptide biomarker. Such biosensors are useful in detecting and/or quantifying a peptide of the invention.

Diagnostic kits for the diagnosis and monitoring of schizophrenia or other psychotic disorder are described herein. In one embodiment, the kits additionally contain a biosensor capable of detecting and/or quantifying a peptide biomarker. Monitoring methods of the invention can be used to monitor onset, progression, stabilisation, amelioration and/or remission.

In methods of diagnosing or monitoring according to the invention, detecting and/or quantifying the peptide biomarker in a biological sample from a test subject may be performed on two or more occasions. Comparisons may be made between the level of biomarker in samples taken on two or more occasions. Assessment of any change in the level of the peptide biomarker in samples taken on two or more occasions may be performed. Modulation of the peptide biomarker level is useful as an indicator of the state of schizophrenia or other psychotic disorder or predisposition thereto. An increase in the level of the biomarker, over time is indicative of onset or progression, i.e. worsening of this disorder, whereas a decrease in the level of the peptide biomarker indicates amelioration or remission of the disorder, or vice versa.

A method of diagnosis of or monitoring according to the invention may comprise quantifying the peptide biomarker in a test biological sample from a test subject and comparing the level of the peptide present in said test sample with one or more controls.

The control used in a method of the invention can be one or more control(s) selected from the group consisting of: the level of biomarker peptide found in a normal control sample from a normal subject, a normal biomarker peptide level; a normal biomarker peptide range, the level in a sample from a subject with schizophrenia or other psychotic disorder, or a diagnosed predisposition thereto; schizophrenia or other psychotic disorder biomarker peptide level, or schizophrenia or other psychotic disorder biomarker peptide range.

In one embodiment, there is provided a method of diagnosing schizophrenia or other psychotic disorder, or predisposition thereto, which comprises:

(a) quantifying the amount of the peptide biomarker in a test biological sample; and (b) comparing the amount of said peptide in said test sample with the amount present in a normal control biological sample from a normal subject. For biomarkers which are increased in patients with schizophrenia or other psychotic disorder, a higher level of the peptide biomarker in the test sample relative to the level in the normal control is indicative of the presence of schizophrenia or other psychotic disorder, or predisposition thereto; an equivalent or lower level of the peptide in the test sample relative to the normal control is indicative of absence of schizophrenia or other psychotic disorder and/or absence of a predisposition thereto. For biomarkers which are decreased in patients with schizophrenia or other psychotic disorder, a lower level of the peptide biomarker in the test sample relative to the level in the normal control is indicative of the presence of schizophrenia or other psychotic disorder, or predisposition thereto; an equivalent or lower level of the peptide in the test sample relative to the normal control is indicative of absence of schizophrenia or other psychotic disorder and/or absence of a predisposition thereto.

The term "diagnosis" as used herein encompasses identification, confirmation, and/or characterisation of schizophrenia or other psychotic disorder, or predisposition thereto. By predisposition it is meant that a subject does not currently present with the disorder, but is liable to be affected by the disorder in time. Methods of monitoring and of diagnosis according to the invention are useful to confirm the existence of a disorder, or predisposition thereto; to monitor development of the disorder by assessing onset and progression, or to assess amelioration or regression of the disorder. Methods of monitoring and of diagnosis are also useful in methods for assessment of clinical screening, prognosis, choice of therapy, evaluation of therapeutic benefit, i.e. for drug screening and drug development.

Efficient diagnosis and monitoring methods provide very powerful "patient solutions" with the potential for improved prognosis, by establishing the correct diagnosis, allowing rapid identification of the most appropriate treatment (thus lessening unnecessary exposure to harmful drug side effects), reducing "downtime" and relapse rates.

Also provided is a method of monitoring efficacy of a therapy for schizophrenia or other psychotic disorder in a subject having such a disorder, suspected of having such a disorder, or of being predisposed thereto, comprising detecting and/or quantifying the peptide present in a biological sample from said subject. In monitoring methods, test samples may be taken on two or more occasions. The method may further comprise comparing the level of the biomarker(s) present in the test sample with one or more control(s) and/or with one or more previous test sample(s) taken earlier from the same test subject, e.g. prior to commencement of therapy, and/or from the same test subject at an earlier stage of therapy. The method may comprise detecting a change in the level of the biomarker(s) in test samples taken on different occasions.

The invention provides a method for monitoring efficacy of therapy for schizophrenia or other psychotic disorder in a subject, comprising :

(a) quantifying the amount of the peptide biomarker; and

(b) comparing the amount of said peptide in said test sample with the amount present in one or more control(s) and/or one or more previous test sample(s) taken at an earlier time from the same test subject.

For biomarkers which are increased in patients with schizophrenia or other psychotic disorder, a decrease in the level of the peptide biomarker in the test sample relative to the level in a previous test sample taken earlier from the same test subject is indicative of a beneficial effect, e.g . stabilisation or improvement, of said therapy on the disorder, suspected disorder or predisposition thereto. For biomarkers which are decreased in patients with schizophrenia or other psychotic disorder, an increase in the level of the peptide biomarker in the test sample relative to the level in a previous test sample taken earlier from the same test subject is indicative of a beneficial effect, e.g . stabilisation or improvement, of said therapy on the disorder, suspected disorder or predisposition thereto. Methods for monitoring efficacy of a therapy can be used to monitor the therapeutic effectiveness of existing therapies and new therapies in human subjects and in non-human animals (e.g. in animal models). These monitoring methods can be incorporated into screens for new drug substances and combinations of substances.

Suitably, the time elapsed between taking samples from a subject undergoing diagnosis or monitoring will be 3 days, 5 days, a week, two weeks, a month, 2 months, 3 months, 6 or 12 months. Samples may be taken prior to and/or during and/or following an anti-psychotic therapy. Samples can be taken at intervals over the remaining life, or a part thereof, of a subject.

The term "detecting" as used herein means confirming the presence of the peptide biomarker present in the sample. Quantifying the amount of the biomarker present in a sample may include determining the concentration of the peptide biomarker present in the sample. Detecting and/or quantifying may be performed directly on the sample, or indirectly on an extract therefrom, or on a dilution thereof.

In alternative aspects of the invention, the presence of the peptide biomarker is assessed by detecting and/or quantifying antibody or fragments thereof capable of specific binding to the biomarker that are generated by the subject's body in response to the peptide and thus are present in a biological sample from a subject having schizophrenia or other psychotic disorder or a predisposition thereto.

Detecting and/or quantifying can be performed by any method suitable to identify the presence and/or amount of a specific protein in a biological sample from a patient or a purification or extract of a biological sample or a dilution thereof. In methods of the invention, quantifying may be performed by measuring the concentration of the peptide biomarker in the sample or samples. Biological samples that may be tested in a method of the invention include cerebrospinal fluid (CSF), whole blood, blood serum, plasma, urine, saliva, or other bodily fluid (stool, tear fluid, synovial fluid, sputum), breath, e.g . as condensed breath, or an extract or purification therefrom, or dilution thereof. Biological samples also include tissue homogenates, tissue sections and biopsy specimens from a live subject, or taken post-mortem. The samples can be prepared, for example where appropriate diluted or concentrated, and stored in the usual manner.

The biomarker may be directly detected, e.g. by SELDI or MALDI-TOF. Alternatively, the biomarker may be detected directly or indirectly via interaction with a ligand or ligands such as an antibody or a biomarker-binding fragment thereof, or other peptide, or ligand, e.g. aptamer, or oligonucleotide, capable of specifically binding the biomarker. The ligand may possess a detectable label, such as a luminescent, fluorescent or radioactive label, and/or an affinity tag. For example, detecting and/or quantifying can be performed by one or more method(s) selected from the group consisting of: SELDI (-TOF), MALDI (- TOF), a 1-D gel-based analysis, a 2-D gel-based analysis, Mass spec (MS), reverse phase (RP) LC, size permeation (gel filtration), ion exchange, affinity, HPLC, UPLC and other LC or LC MS-based techniques. Appropriate LC MS techniques include ICAT® (Applied Biosystems, CA, USA), or iTRAQ® (Applied Biosystems, CA, USA). Liquid chromatography (e.g. high pressure liquid chromatography (HPLC) or low pressure liquid chromatography (LPLC)), thin- layer chromatography, NMR (nuclear magnetic resonance) spectroscopy could also be used.

Methods of diagnosing or monitoring according to the invention may comprise analysing a sample of cerebrospinal fluid (CSF) by SELDI TOF or MALDI TOF to detect the presence or level of the peptide biomarker. These methods are also suitable for clinical screening, prognosis, monitoring the results of therapy, identifying patients most likely to respond to a particular therapeutic treatment, for drug screening and development, and identification of new targets for drug treatment. Detecting and/or quantifying the peptide biomarkers may be performed using an immunological method, involving an antibody, or a fragment thereof capable of specific binding to the peptide biomarker. Suitable immunological methods include sandwich immunoassays, such as sandwich ELISA, in which the detection of the peptide biomarkers is performed using two antibodies which recognize different epitopes on a peptide biomarker; radioimmunoassays (RIA), direct, indirect or competitive enzyme linked immunosorbent assays (ELISA), enzyme immunoassays (EIA), Fluorescence immunoassays (FIA), western blotting, immunoprecipitation and any particle-based immunoassay (e.g . using gold, silver, or latex particles, magnetic particles, or Q-dots). Immunological methods may be performed, for example, in microtitre plate or strip format.

Immunological methods in accordance with the invention may be based, for example, on any of the following methods.

Immunoprecipitation is the simplest immunoassay method; this measures the quantity of precipitate, which forms after the reagent antibody has incubated with the sample and reacted with the target antigen present therein to form an insoluble aggregate. Immunoprecipitation reactions may be qualitative or quantitative.

In particle immunoassays, several antibodies are linked to the particle, and the particle is able to bind many antigen molecules simultaneously. This greatly accelerates the speed of the visible reaction. This allows rapid and sensitive detection of the biomarker.

In immunonephelometry, the interaction of an antibody and target antigen on the biomarker results in the formation of immune complexes that are too small to precipitate. However, these complexes will scatter incident light and this can be measured using a nephelometer. The antigen, i.e. biomarker, concentration can be determined within minutes of the reaction.

Radioimmunoassay (RIA) methods employ radioactive isotopes such as I¹²⁵ to label either the antigen or antibody. The isotope used emits gamma rays, which are usually measured following removal of unbound (free) radiolabel . The major advantages of RIA, compared with other immunoassays, are higher sensitivity, easy signal detection, and well-established, rapid assays. The major disadvantages are the health and safety risks posed by the use of radiation and the time and expense associated with maintaining a licensed radiation safety and disposal program. For this reason, RIA has been largely replaced in routine clinical laboratory practice by enzyme immunoassays.

Enzyme (EIA) immunoassays were developed as an alternative to radioimmunoassays (RIA). These methods use an enzyme to label either the antibody or target antigen. The sensitivity of EIA approaches that for RIA, without the danger posed by radioactive isotopes. One of the most widely used

EIA methods for detection is the enzyme-linked immunosorbent assay (ELISA).

ELISA methods may use two antibodies one of which is specific for the target antigen and the other of which is coupled to an enzyme, addition of the substrate for the enzyme results in production of a chemiluminescent or fluorescent signal.

Fluorescent immunoassay (FIA) refers to immunoassays which utilize a fluorescent label or an enzyme label which acts on the substrate to form a fluorescent product. Fluorescent measurements are inherently more sensitive than colorimetric (spectrophotometric) measurements. Therefore, FIA methods have greater analytical sensitivity than EIA methods, which employ absorbance (optical density) measurement.

Chemiluminescent immunoassays utilize a chemiluminescent label, which produces light when excited by chemical energy; the emissions are measured using a light detector. Immunological methods according to the invention can thus be performed using well-known methods. Any direct (e.g ., using a sensor chip) or indirect procedure may be used in the detection of peptide biomarkers of the invention. The Biotin-Avidin or Biotin-Streptavidin systems are generic labelling systems that can be adapted for use in immunological methods of the invention. One binding partner (hapten, antigen, ligand, aptamer, antibody, enzyme etc) is labelled with biotin and the other partner (surface, e.g . well, bead, sensor etc) is labelled with avidin or streptavidin. This is conventional technology for immunoassays, gene probe assays and (bio)sensors, but is an indirect immobilisation route rather than a direct one. For example a biotinylated ligand (e.g. antibody or aptamer) specific for a peptide biomarker of the invention may be immobilised on an avidin or streptavidin surface, the immobilised ligand may then be exposed to a sample containing or suspected of containing the peptide biomarker in order to detect and/or quantify a peptide biomarker of the invention. Detection and/or quantification of the immobilised antigen may then be performed by an immunological method as described herein. The term "antibody" as used herein includes, but is not limited to : polyclonal, monoclonal, bispecific, humanised or chimeric antibodies, single chain antibodies, Fab fragments and F(ab')₂ fragments, fragments produced by a Fab expression library, anti-idiotypic (anti-Id) antibodies and epitope-binding fragments of any of the above. The term "antibody" as used herein also refers to immunoglobulin molecules and immunologically-active portions of immunoglobulin molecules, i.e., molecules that contain an antigen binding site that specifically binds an antigen. The immunoglobulin molecules of the invention can be of any class (e. g ., IgG, IgE, IgM, IgD and IgA) or subclass of immunoglobulin molecule.

The identification of key biomarkers specific to a disease is central to integration of diagnostic procedures and therapeutic regimes. Using predictive biomarkers appropriate diagnostic tools such as biosensors can be developed, accordingly, in methods and uses of the invention, detecting and quantifying can be performed using a biosensor, microanalytical system, microengineered system, microseparation system, immunochromatography system or other suitable analytical devices. The biosensor may incorporate an immunological method for detection of the biomarker(s), electrical, thermal, magnetic, optical (e.g. hologram) or acoustic technologies. Using such biosensors, it is possible to detect the target biomarker(s) at the anticipated concentrations found in biological samples.

Thus, according to a further aspect of the invention there is provided an apparatus for diagnosing or monitoring schizophrenia or other psychotic disorder which comprises a biosensor, microanalytical, microengineered, microseparation and/or immunochromatography system configured to detect and/or quantify any of the biomarkers defined herein. The biomarker(s) of the invention can be detected using a biosensor incorporating technologies based on "smart" holograms, or high frequency acoustic systems, such systems are particularly amenable to "bar code" or array configurations.

In smart hologram sensors (Smart Holograms Ltd, Cambridge, UK), a holographic image is stored in a thin polymer film that is sensitised to react specifically with the biomarker. On exposure, the biomarker reacts with the polymer leading to an alteration in the image displayed by the hologram. The test result read-out can be a change in the optical brightness, image, colour and/or position of the image. For qualitative and semi-quantitative applications, a sensor hologram can be read by eye, thus removing the need for detection equipment. A simple colour sensor can be used to read the signal when quantitative measurements are required. Opacity or colour of the sample does not interfere with operation of the sensor. The format of the sensor allows multiplexing for simultaneous detection of several substances. Reversible and irreversible sensors can be designed to meet different requirements, and continuous monitoring of a particular biomarker of interest is feasible.

Suitably, biosensors for detection of one or more biomarkers of the invention combine biomolecular recognition with appropriate means to convert detection of the presence, or quantitation, of the biomarker in the sample into a signal . Biosensors can be adapted for "alternate site" diagnostic testing, e.g. in the ward, outpatients' department, surgery, home, field and workplace. Biosensors to detect one or more biomarkers of the invention include acoustic, plasmon resonance, holographic and microengineered sensors. Imprinted recognition elements, thin film transistor technology, magnetic acoustic resonator devices and other novel acousto-electrical systems may be employed in biosensors for detection of the one or more biomarkers of the invention.

Methods involving detection and/or quantification of one or more peptide biomarkers of the invention can be performed on bench-top instruments, or can be incorporated onto disposable, diagnostic or monitoring platforms that can be used in a non-laboratory environment, e.g . in the physician's office or at the patient's bedside. Suitable biosensors for performing methods of the invention include "credit" cards with optical or acoustic readers. Biosensors can be configured to allow the data collected to be electronically transmitted to the physician for interpretation and thus can form the basis for e-neuromedicine.

Any suitable animal may be used as a subject non-human animal, for example a non-human primate, horse, cow, pig, goat, sheep, dog, cat, fish, rodent, e.g . guinea pig, rat or mouse; insect (e.g . Drosophila), amphibian (e.g . Xenopus) or C. elegans.

The test substance can be a known chemical or pharmaceutical substance, such as, but not limited to, an anti-psychotic disorder therapeutic; or the test substance can be novel synthetic or natural chemical entity, or a combination of two or more of the aforesaid substances.

There is provided a method of identifying a substance capable of promoting or suppressing the generation of the peptide biomarker in a subject, comprising exposing a test cell to a test substance and monitoring the level of the peptide biomarker within said test cell, or secreted by said test cell .

The test cell could be prokaryotic, however a eukaryotic cell will suitably be employed in cell-based testing methods. Suitably, the eukaryotic cell is a yeast cell, insect cell, Drosophila cell, amphibian cell (e.g . from Xenopus), C. elegans cell or is a cell of human, non-human primate, equine, bovine, porcine, caprine, ovine, canine, feline, piscine, rodent or murine origin.

In methods for identifying substances of potential therapeutic use, non-human animals or cells can be used that are capable of expressing the peptide.

Screening methods also encompass a method of identifying a ligand capable of binding to the peptide biomarker according to the invention, comprising incubating a test substance in the presence of the peptide biomarker in conditions appropriate for binding, and detecting and/or quantifying binding of the peptide to said test substance.

High-throughput screening technologies based on the biomarker, uses and methods of the invention, e.g . configured in an array format, are suitable to monitor biomarker signatures for the identification of potentially useful therapeutic compounds, e.g. ligands such as natural compounds, synthetic chemical compounds (e.g. from combinatorial libraries), peptides, monoclonal or polyclonal antibodies or fragments thereof, which may be capable of binding the biomarker.

Methods of the invention can be performed in array format, e.g . on a chip, or as a multiwell array. Methods can be adapted into platforms for single tests, or multiple identical or multiple non-identical tests, and can be performed in high throughput format. Methods of the invention may comprise performing one or more additional, different tests to confirm or exclude diagnosis, and/or to further characterise a condition.

The invention further provides a substance, e.g . a ligand, identified or identifiable by an identification or screening method or use of the invention. Such substances may be capable of inhibiting, directly or indirectly, the activity of the peptide biomarker, or of suppressing generation of the peptide biomarker. The term "substances" includes substances that do not directly bind the peptide biomarker and directly modulate a function, but instead indirectly modulate a function of the peptide biomarker. Ligands are also included in the term substances; ligands of the invention (e.g . a natural or synthetic chemical compound, peptide, aptamer, oligonucleotide, antibody or antibody fragment) are capable of binding, suitably specific binding, to the peptide. The invention further provides a substance according to the invention for use in the treatment of schizophrenia or other psychotic disorder, or predisposition thereto.

Also provided is the use of a substance according to the invention in the treatment of schizophrenia or other psychotic disorder, or predisposition thereto.

Also provided is the use of a substance according to the invention as a medicament. A kit for diagnosing or monitoring schizophrenia or other psychotic disorder, or predisposition thereto is provided . Suitably a kit according to the invention may contain one or more components selected from the group : a ligand specific for the peptide biomarker or a structural/shape mimic of the peptide biomarker, one or more controls, one or more reagents and one or more consumables; optionally together with instructions for use of the kit in accordance with any of the methods defined herein.

The identification of biomarkers for schizophrenia or other psychotic disorder permits integration of diagnostic procedures and therapeutic regimes. Currently there are significant delays in determining effective treatment and hitherto it has not been possible to perform rapid assessment of drug response. Traditionally, many anti-psychotic therapies have required treatment trials lasting weeks to months for a given therapeutic approach. Detection of a peptide biomarker of the invention can be used to screen subjects prior to their participation in clinical trials. The biomarkers provide the means to indicate therapeutic response, failure to respond, unfavourable side-effect profile, degree of medication compliance and achievement of adequate serum drug levels. The biomarkers may be used to provide warning of adverse drug response. Biomarkers are useful in development of personalized brain therapies, as assessment of response can be used to fine-tune dosage, minimise the number of prescribed medications, reduce the delay in attaining effective therapy and avoid adverse drug reactions. Thus by monitoring a biomarker of the invention, patient care can be tailored precisely to match the needs determined by the disorder and the pharmacogenomic profile of the patient, the biomarker can thus be used to titrate the optimal dose, predict a positive therapeutic response and identify those patients at high risk of severe side effects.

Biomarker-based tests provide a first line assessment of 'new' patients, and provide objective measures for accurate and rapid diagnosis, in a time frame and with precision, not achievable using the current subjective measures.

Furthermore, diagnostic biomarker tests are useful to identify family members or patients at high risk of developing schizophrenia or other psychotic disorder. This permits initiation of appropriate therapy, or preventive measures, e.g . managing risk factors. These approaches are recognised to improve outcome and may prevent overt onset of the disorder.

Biomarker monitoring methods, biosensors and kits are also vital as patient monitoring tools, to enable the physician to determine whether relapse is due to worsening of the disorder, poor patient compliance or substance abuse. If pharmacological treatment is assessed to be inadequate, then therapy can be reinstated or increased; a change in therapy can be given if appropriate. As the biomarkers are sensitive to the state of the disorder, they provide an indication of the impact of drug therapy or of substance abuse.

The following study was conducted by comparing serum samples collected from first onset schizophrenia patients before and after treatment with olanzapine, risperidone, quetiapine or a mixture. Samples were analyzed by label-free data independent nanoLC-MS^E technique and proteins which were significantly changing after treatment was reported.

Materials and Methods Demographics

The study included serum samples taken from first onset drug naive or minimally treated schizophrenia patients, before and after treatment with antipsychotic medication in clinical centre 1 (n = 23) and clinical centre 2 (n = 23). Patients were assessed on the day of sample collection using the Positive and Negative Syndrome Scale (PANSS). Average scores of initially antipsychotic naive patients in centre 1 were 86.1 ±21.4 before and 70.0 ± 28.4 after treatment; average scores of initially antipsychotic naive patients in centre 2 were 71.2 ± 21.0 before and 53.3 ± 15.6 after treatment. Patients from both centres were treated for four weeks and their psychopathology was assessed using the PANSS rating scale before and after the treatment period by experienced clinicians.

Table 1: Patient Demographics

Risperidone, Quetiapine and

Olanzapine

mixture

Number of

23 23

patients

Sex (m/f) 16 / 7 18 / 5

Age 30.3 ± 10.5 28.3 ± 11.1

BMI 22.6 ± 3.1 22.7 ± 2.4

smoker 6 8

Patient recruitment and sample collection

The subjects were recruited from the Departments of Psychiatry at the

Universities of Cologne (center 1) and Muenster (center 2). Schizophrenia was diagnosed based on the Structured Clinical Interview for Diagnostic (SCID) and Statistical Manual (DSM)-IV and fulfilled criteria for the paranoid subtype (classification 295.30).

The medical faculty ethical committees of the respective universities in Germany approved the protocols of the study. Informed consent was given in writing by all participants and clinical investigations were conducted according to the principles expressed in the Declaration of Helsinki. Blood samples were collected from all subjects between 8: 00 and 12 : 00 am (non-fasting) immediately after clinical diagnosis into S-Monovette 7.5ml_ serum tubes (Sarstedt; Numbrecht, Germany). These were left at room temperature for 2 hours to allow for blood coagulation and then centrifuged at 4000 x g for 5 minutes. The resulting supernatants were stored at -80°C in Low Binding Eppendorf tubes (Eppendorf; Hamburg, Germany).

Sample Preparation

Serum samples were prepared randomly and blindly without pooling . 40μΙ of each sample was subjected to immunodepletion using MARS14 (Multiple Affinity Removal System, Agilent, Santa Clara, CA, USA) on a fast protein liquid chromatography system (AKTA™ purifier UPC 10, GE Healthcare). The flow through, containing the moderate to low abundance proteins, was then

concentrated using spin columns with a 5kDa molecular weight cut-off (Agilent). The samples were reduced by adding 5 mM dithiolthreitol (Sigma Aldrich, St. Louis, MI, USA) and incubated for 30 min at 60°C, and alkylated with 10 mM iodoacetemide (Sigma) with incubation in the dark for 30 min at 21°C. The proteins were digested using trypsin (Promega, Madison, WI, USA) at a ratio of 1 : 50 (w/w trypsin/protein) for 16 hours at 37°C. The digestion was stopped by adding HCI to a concentration of 150mM . The samples were stored in -80°C.

LC-MS analysis

HPLC grade solvents were used for all chromatographic steps. Each sample was loaded using split-less nano-Ultra Performance Liquid Chromatography (lOkpsi nanoAcquity; Waters, Milford, MA, USA) in duplicate. Buffers used were : A) H₂0 + 0.1% formic acid and B) acetonitrile + 0.1% formic acid. Desalting of samples was performed online using a reverse-phase C18 trapping column (180pm i.d ., 20mm length, 5pm particle size, Waters). The peptides in samples were separated using a C18 BEH nano-column (75pm i.d., 200mm length, 1.7pm particle size, Waters) at 0.3pL/minute.

The nanoLC was coupled online through a nanoESI emitter (7 cm length, 10 mm tip; New Objective, Woburn, MA, USA) to a quadrupole time-of-flight (Qtof) mass spectrometer (Qtof Premier, Waters). Data were acquired using Masslynx version 4.1, in MS^E (also known as data independent analysis), positive ion mode in which the quadrupole is set to transfer all ions while the collision energy is alternated from low to high throughout the acquisition time. In low-energy (MSI) scans, the collision energy was set to 5 eV and this was ramped from 17 to 40 eV for high-energy scans. In both, mass range was set to 50 to 1990 Da. Scan time was set to 0.6 seconds. This mode enables accurate mass measurement of intact peptides and fragments at a high sampling rate as well as conservation of the chromatographic profile for both intact peptides and fragments. A reference compound (Glu-Fibrinopeptide B; Sigma) was infused continuously for external calibration using a LockSpray and scanned every 30 seconds.

Data Processing, Searching and Analysis

Data acquired in continuum format were processed using ProteinLynx Global Server (PLGS) version 2.4 (Waters) and with Rosetta Biosoftware Elucidator version 3.3 (Seattle, WA, USA). Elucidator was used for alignment of raw MSI data in time and m/z. Aligned peaks (features) were extracted and quantitative measurement was obtained by integration of three dimensional volumes (time, m/z, intensity) of each feature (i.e. three dimensional version of the extracted ion chromatogram method). Although scaling (normalization) techniques are typically applied in label-free analysis, either using an internal standard or total ion current (TIC), it was chosen not to apply them in any of the experiments in order to obtain a true measure of the platform quantitation variability.

In parallel, database searching was carried out using PLGS version 2.4 with the ion accounting algorithm described by Li et al (Proteomics 2009; 9(6) : 1696). Processed data were searched against the Swiss-Prot protein database (version 57; 20,334 entries) amended with sequences of yeast enolase (P00924) and porcine trypsin (P00761). One missed cleavage was allowed and fixed modification was set to carbamidomethylation of cysteines. Variable modifications included oxidation of methionine, phosphorylation of serine, threonine or tyrosine and N glycosylation. The criteria for protein identification were set to minimum of 3 fragments per peptide and 7 fragments per protein. Data were also searched against the randomized version of each database and maximum false identification rate was set to 4% at the protein level . All search results were imported into Elucidator and were used to annotate aligned features. In cases where a feature was identified multiple times, the highest scoring result was used .

Protein abundance was calculated by summing peptide intensities per protein. A two tailed paired Student's T-Test was used to identify differential expression, after logarithmic transformation. Significance was set at p value of less than 0.05. Fold changes were calculated by mean intensity after treatment divided by mean intensity before treatment (after/before).

Results

Centre 1 statistical p

Fold

Protein Description Protein Names value, paired Ratio Pep count

Change

Ttest

Phospholipid transfer protein PLTP HUMAN, P55058 0.00001 1.42 1.42 1

Lumican LUM HUMAN, P51884 0.000005 1.19 1.19 25

Cartilage oligomeric matrix protein COMP_HUMAN, P49747 0.000007 1.23 1.23 6

Keratin, type II cytoskeletal 5 K2C5_HUMAN, P13647 0.00024 1.32 1.32 2

Zinc finger protein 57 ZNF57 HUMAN, Q68EA5 0.00191 1.19 1.19 2

C-type mannose receptor 2 MRC2 HUMAN, Q9UBG0 0.00214 1.27 1.27 1

Beta-Ala-His dipeptidase CNDP1 HUMAN, Q96KN2 0.00245 1.12 1.12 21

Mitogen-activated protein kinase 2 M4K2 HUMAN, Q12851 0.00345 1.14 1.14 2

Apolipoprotein C-l APOCl_HUMAN, P02654 0.00456 1.26 1.26 2

Attractin ATRN HUMAN, 075882 0.00493 1.04 1.04 39

Hemoglobin subunit epsilon HBE HUMAN, P02100 0.00619 1.34 1.34 1

Ankyrin repeat domain-containing

ANR58 HUMAN, A6NJG2 0.00690 1.18 1.18 2 protein 58

Actin, aortic smooth muscle ACTA HUMAN, P62736 0.00832 1.22 1.22 1

EGF-containing fibulin-like extracellular

FBLN3 HUMAN, Q12805 0.00892 1.25 1.25 1 matrix protein 1

Dual specificity protein phosphatase

CC14B_HUMAN, 060729 0.00947 1.25 1.25 1 CDC14B

Nesprin-3 SYNE3 HUMAN, Q6ZMZ3 0.00960 1.19 1.19 3

Complement Clr subcomponent C1R HUMAN, P00736 0.01039 1.07 1.07 48

Protein MCM10 homolog MCM10 HUMAN, Q7L590 0.01052 1.17 1.17 3

Putative zinc-alpha-2-glycoprotein-like 1 ZAGL1 HUMAN, A8MT79 0.01059 1.11 1.11 10

Ceruloplasmin CERU HUMAN, P00450 0.01133 1.08 1.08 160

Leucine-rich alpha-2-glycoprotein A2GL HUMAN, P02750 0.01140 1.15 1.15 27

Elongation factor 1-gamma EF1G HUMAN, P26641 0.01152 1.26 1.26 1 lg gamma-1 chain C region IGHG1 HUMAN, P01857 0.01152 1.18 1.18 1

Insulin-like growth factor-binding

IBP3_HUMAN, P17936 0.01249 1.12 1.12 9 protein 3

N-acetylated-alpha-linked acidic

NALD2 HUMAN, Q9Y3Q0 0.01329 1.15 1.15 4 dipeptidase 2

Uncharacterized protein C9orf75 CI075_HUMAN, Q4KMQ1 0.01726 1.13 1.13 1

Protein FAM83D FA83D HUMAN, Q9H4H8 0.01893 1.08 1.08 3

Cytoplasmic aconitate hydratase ACOC_HUMAN, P21399 0.01895 1.14 1.14 1

BTB/POZ domain-containing protein

KCD17 HUMAN, Q8N5Z5 0.01973 1.14 1.14 2 KCTD17

WD repeat-containing protein 23 WDR23 HUMAN, Q8TEB1 0.02036 1.26 1.26 1

Zinc finger protein 287 ZN287_HUMAN, Q9HBT7 0.02038 1.12 1.12 1

Mannan-binding lectin serine protease 1 MASP1 HUMAN, P48740 0.02168 1.14 1.14 2

Thrombospondin-2 TSP2_HUMAN, P35442 0.02245 1.12 1.12 10

Ras-related protein Rab-18 RAB18 HUMAN, Q9NP72 0.02288 1.30 1.30 1

Apolipoprotein B-100 APOB HUMAN, P04114 0.02382 1.07 1.07 639

Protein FAM98C FA98C HUMAN, Q17RN3 0.02448 1.16 1.16 1

DNA-directed RNA polymerase 1 subunit

RPA1 HUMAN, 095602 0.02788 1.14 1.14 6 RPA1

Zinc-alpha-2-glycoprotein ZA2G HUMAN, P25311 0.02800 -1.05 0.95 40 lg lambda chain V-ll region VIL LV208_HUMAN, P01711 0.02813 1.14 1.14 1

Carboxypeptidase N subunit 2 CPN2_HUMAN, P22792 0.02839 -1.04 0.96 27

Polyadenylate-binding protein 4 PABP4 HUMAN, Q13310 0.02943 1.12 1.12 3

Septin-13 SEP13_HUMAN, A8MT51 0.03093 1.15 1.15 1

Zinc finger protein 189 ZN189_HUMAN, 075820 0.03157 1.13 1.13 2

Leucine-rich glioma-inactivated protein

LGI1 HUMAN, 095970 0.03196 1.13 1.13 1 1

Uncharacterized protein KIAA0552 K0552_HUMAN, 060299 0.03252 1.13 1.13 1

Fetuin-B FETUB HUMAN, Q9UGM5 0.03253 1.07 1.07 15

Apolipoprotein C-ll APOC2_HUMAN, P02655 0.03347 1.20 1.20 4

Transthyretin TTHY HUMAN, P02766 0.03357 1.08 1.08 2

Inter-alpha-trypsin inhibitor heavy chain

ITIH1 HUMAN, P19827 0.03374 -1.06 0.94 108 HI

lg mu heavy chain IGHM HUMAN, P01871 0.04033 1.50 1.50 2

Ubiquilin-3 UBQL3 HUMAN, Q9H347 0.04072 1.17 1.17 1

Serine/threonine-protein kinase PDIK1L PDK1L HUMAN, Q8N165 0.04389 -1.19 0.84 1

Complement C2 C02_HUMAN, P06681 0.04529 1.04 1.04 69

T-cell surface glycoprotein CDlb CD1B HUMAN, P29016 0.04589 1.14 1.14 3

Vitamin D-binding protein VTDB HUMAN, P02774 0.04787 1.04 1.04 105

Centre 2

statistical p

Fold

Protein Description Protein Names value, paired Ratio Pep count

Change

Ttest

Lumican LUM HUMAN, P51884 0.00002 1.25 1.25 24

Thrombospondin-4 TSP4_HUMAN, P35443 0.00036 1.13 1.13 2

EGF-containing fibulin-like extracellular

FBLN3 HUMAN, Q12805 0.00111 1.26 1.26 1 matrix protein 1 Beta-l,4-galactosyltransferase 3 B4GT3 HUMAN, 060512 0.00123 1.20 1.20 1

60S ribosomal export protein NMD3 NMD3 HUMAN, Q96D46 0.00204 1.79 1.79 1

Complement factor H CFAH HUMAN, P08603 0.00238 1.05 1.05 181

Structural maintenance of

SMC4_HUMAN, Q9NTJ3 0.00250 1.31 1.31 1 chromosomes protein 4

Kinesin-like protein KIF16B KI16B HUMAN, Q96L93 0.00261 1.13 1.13 9

Myelin protein PO MYPO HUMAN, P25189 0.00291 1.24 1.24 1

Forkhead box protein P3 FOXP3_HUMAN, Q9BZS1 0.00296 1.48 1.48 1

Apolipoprotein C-ll APOC2_HUMAN, P02655 0.00343 1.36 1.36 5

NACHT, LRR and PYD domains-

NAL14_HUMAN, Q86W24 0.00396 1.18 1.18 1 containing protein 14

Apolipoprotein A-IV APOA4 HUMAN, P06727 0.00414 1.13 1.13 110

Protein CLN8 CLN8 HUMAN, Q9UBY8 0.00459 1.17 1.17 2

Apolipoprotein C-lll APOC3_HUMAN, P02656 0.00483 1.37 1.37 11

Proteasome subunit alpha type-2 PSA2_HUMAN, P25787 0.00548 1.17 1.17 1

Glycosyltransferase-like protein LARGEl LARGE HUMAN, 095461 0.00680 1.08 1.08 1

COMA1 HUMAN,

Collagen alpha-l(XXII) chain 0.00704 1.08 1.08 5

Q8NFW1

Sulfhydryl oxidase 1 QS0X1_HUMAN, 000391 0.00709 1.20 1.20 2

RING finger protein 214 RN214 HUMAN, Q8ND24 0.00724 1.13 1.13 3

Alpha-2-HS-glycoprotein FETUA HUMAN, P02765 0.00733 1.06 1.06 74

Plasma protease CI inhibitor IC1_HUMAN, P05155 0.00861 -1.04 0.96 80

Apolipoprotein(a) APOA HUMAN, P08519 0.01141 1.20 1.20 2

Properdin PROP_HUMAN, P27918 0.01216 1.11 1.11 4

Complement factor H-related protein 1 FHR1 HUMAN, Q03591 0.01303 1.03 1.03 19

Apolipoprotein C-l AP0C1_HUMAN, P02654 0.01363 1.35 1.35 2

Apolipoprotein E APOE HUMAN, P02649 0.01667 1.11 1.11 52

Platelet basic protein CXCL7_HUMAN, P02775 0.01896 -1.08 0.92 10

Paxillin PAXI_HUMAN, P49023 0.01934 1.15 1.15 1

Angiotensinogen ANGT HUMAN, P01019 0.02000 -1.05 0.95 41

Apolipoprotein B-100 APOB HUMAN, P04114 0.02233 1.04 1.04 686

Clusterin CLUS_HUMAN, P10909 0.02617 1.03 1.03 56

Complement component C8 beta chain C08B_HUMAN, P07358 0.02806 -1.07 0.93 48

Pigment epithelium-derived factor PEDF HUMAN, P36955 0.02883 1.05 1.05 39

Fetuin-B FETUB HUMAN, Q9UGM5 0.02914 1.06 1.06 13

CD5 antigen-like CD5L HUMAN, 043866 0.03007 1.11 1.11 1

Complement Clr subcomponent C1R HUMAN, P00736 0.03322 1.04 1.04 60

Keratin, type 1 cytoskeletal 10 K1C10_HUMAN, P13645 0.03371 1.08 1.08 2

Biotinidase BTD HUMAN, P43251 0.03452 1.04 1.04 12

Apolipoprotein M APOM HUMAN, 095445 0.03461 1.13 1.13 1

Pregnancy zone protein PZP_HUMAN, P20742 0.03628 1.03 1.03 44

F-box only protein 11 FBX11 HUMAN, Q86XK2 0.03793 1.07 1.07 1

AP20 region protein 1 APRG 1 HUMAN, Q8IVJ8 0.04104 1.09 1.09 1

Gelsolin GELS HUMAN, P06396 0.04189 1.04 1.04 93

Cold shock domain-containing protein

CSDE1 HUMAN, 075534 0.04246 1.09 1.09 1 El KH domain-containing, RNA-binding,

KHDR1 HUMAN, Q07666 0.04355 1.17 1.17 1 signal transduction-associated protein 1

Keratin, type 1 cytoskeletal 26 K1C26_HUMAN, Q7Z3Y9 0.04564 1.08 1.08 1

Ig mu chain C region IGHM HUMAN, P01871 0.04906 1.09 1.09 1

Complement component C7 C07_HUMAN, P10643 0.04919 -1.04 0.96 75

Synaptophysin-like protein 1 SYPL1 HUMAN, Q16563 0.04931 -1.10 0.91 1

Identification of Apolipoprotein CII as an antipsychotic-responsive biomarker Liquid chromatography mass spectrometry (LC-MS) analysis (conducted in accordance with Levin et al. Mol Psychiatry. 2010; 15 : 1088-1100) was performed on serum samples after 4 weeks treatment (T4) with

risperidone/quetiapine (n = 23 subjects) or olanzapine (n = 23 subjects) and the results are provided in Table 2 :

Table 2

The results shown in Table 2 demonstrate a significant increase in serum levels of apolipoprotein CII following a 4 week treatment with either

risperidone/quetiapine or olanzapine.

Enzyme-linked immunoassay analysis (ELISA) of serum samples confirmed that increased levels of serum apolipoprotein CII were present after 4 weeks treatment (T4) with olanzapine in the serum of schizophrenic patients (n = 12). The results of the ELISA study are shown in Figure 1. Similar results were obtained with apolipoprotein CII with samples obtained from patients treated with risperidone/quetiapine (data not shown).

Claims

1. Use of Apoiipoprotein C-II (APOC2) as a biomarker for schizophrenia or other psychotic disorder, or predisposition thereto.

2. Use as defined in claim 1, which additionally comprises the use of one or more further analytes selected from Lumican, Apoiipoprotein B-100 (ApoB) and Fetuin-B (FETUB).

3. Use of Apoiipoprotein C-II (APOC2), Lumican, Apoiipoprotein B-100 (ApoB) and Fetuin-B (FETUB) as a specific panel of analyte biomarkers for schizophrenia or other psychotic disorder, or predisposition thereto.

4. Use as defined in any of claims 1 to 3, which additionally comprises the use of one or more further analytes selected from Phospholipid transfer protein, Cartilage oligomeric matrix protein, Keratin type II cytoskeletal 5 (KRT5), Zinc finger protein 57 (ZFP57), C-type mannose receptor 2 (MRC2), Beta-Ala-His dipeptidase (CNDPl), Mitogen-activated protein kinase 2 (M4K2), Apoiipoprotein C-I, Attractin, Hemoglobin subunit epsilon (HBE), Ankyrin repeat domain- containing protein 58 (ANR58), Actin, aortic smooth muscle (ACTA), EGF- containing fibulin-like extracellular matrix protein 1 (FBLN3), Dual specificity protein phosphatase CDC14B (CC14B), Nesprin-3 (SYNE3), Complement Clr subcomponent, Protein MCM10 homolog (MCM10), Putative zinc-alpha-2- glycoprotein-like 1, Ceruloplasmin, Leucine-rich alpha-2-glycoprotein (A2GL), Elongation factor 1-gamma (EF1G), Ig gamma-1 chain C region (IGHG1),

Insulin-like growth factor-binding protein 3 (IGFBP3), N-acetylated-alpha-linked acidic dipeptidase 2 (NALD2), Uncharacterized protein C9orf75 (CI075), Protein FAM83D (FA83D), Cytoplasmic aconitate hydratase, BTB/POZ domain-containing protein KCTD17, WD repeat-containing protein 23 (WDR23), Zinc finger protein 287 (ZN287), Mannan-binding lectin serine protease 1 (MASP1),

Thrombospondin-2 (TSP-2), Ras-related protein Rab-18 (RAB18), Protein

FAM98C (FA98C), Zinc-alpha-2-glycoprotein, Ig lambda chain V-II region VIL, Carboxypeptidase N subunit 2 (CPN2), Polyadenylate-binding protein 4 (PABP4), Septin-13 (SEP13), Zinc finger protein 189 (ZN189), Leucine-rich glioma- inactivated protein 1 (LGI1), Uncharacterized protein KIAA0552 (K0552), Transthyretin, Inter-alpha-trypsin inhibitor heavy chain H I (ITIH l), Ig mu heavy chain, Ubiquilin-3 (UBQL3), Serine/threonine-protein kinase PDIK1L,

Complement C2 (C02), T-cell surface glycoprotein CDlb (CD1B), Vitamin D- binding protein (VTDB), Thrombospondin-4 (TSP4), Beta-1,4- galactosyltransferase 3 (B4GT3), 60S ribosomal export protein NMD3,

Complement factor H (CFAH), Structural maintenance of chromosomes protein 4 (SMC4), Kinesin-like protein KIF16B (KI16B), Myelin protein P0 (MYPO),

Forkhead box protein P3 (FOXP3), NACHT, LRR and PYD domains-containing protein 14, Apolipoprotein A-IV, Protein CLN8, Apolipoprotein C-III, Proteasome subunit alpha type-2 (PSA2), Glycosyltransferase-like protein LARGE1 (LARGE), Collagen alpha-l(XXII) chain (COMA1), Sulfhydryl oxidase 1 (QSOX1), RING finger protein 214 (RN214), Alpha-2-HS-glycoprotein, Plasma protease CI inhibitor (IC1), Apolipoprotein (a), Properdin (PROP), Complement factor H- related protein 1 (FHR1), Apolipoprotein C-I, Apolipoprotein E, Platelet basic protein (CXCL7), Paxillin (PAXI), Angiotensinogen, Clusterin, Complement component C8 beta chain (C08B), Pigment epithelium-derived factor (PEDF), CD5 antigen-like (CD5L), Complement Clr subcomponent (C1R), Keratin, type I cytoskeletal 10 (K1C10), Biotinidase (BTD), Apolipoprotein M, Pregnancy zone protein (PZP), F-box only protein 11 (FBX11. FBXOl l), AP20 region protein 1 (APRG1), Gelsolin (GELS), Cold shock domain-containing protein El (CSDE1), KH domain-containing, RNA-binding, signal transduction-associated protein 1 (KHDR1), Keratin, type I cytoskeletal 26 (K1C26), Ig mu chain C region (IGHM), Complement component C7 (C07) and Synaptophysin-like protein 1 (SYPL1).

5. Use of Apolipoprotein C-II, Lumican, Apolipoprotein B-100, Fetuin-B, Phospholipid transfer protein, Cartilage oligomeric matrix protein, Keratin type II cytoskeletal 5, Zinc finger protein 57, C-type mannose receptor 2, Beta-Ala-His dipeptidase, Mitogen-activated protein kinase 2, Apolipoprotein C-I, Attractin, Hemoglobin subunit epsilon, Ankyrin repeat domain-containing protein 58, Actin aortic smooth muscle, EGF-containing fibulin-like extracellular matrix protein 1, Dual specificity protein phosphatase CDC14B, Nesprin-3, Complement Clr subcomponent, Protein MCM10 homolog, Putative zinc-alpha-2-glycoprotein-like 1, Ceruloplasmin, Leucine-rich alpha-2-glycoprotein, Elongation factor 1-gamma, Ig gamma-1 chain C region, Insulin-like growth factor-binding protein 3, N- acetylated-alpha-linked acidic dipeptidase 2, Uncharacterized protein C9orf75, Protein FAM83D, Cytoplasmic aconitate hydratase, BTB/POZ domain-containing protein KCTD17, WD repeat-containing protein 23, Zinc finger protein 287, Mannan-binding lectin serine protease 1, Thrombospondin-2, Ras-related protein Rab-18, Protein FAM98C, DNA-directed RNA polymerase I subunit RPA1, Zinc- alpha-2-glycoprotein, Ig lambda chain V-II region VIL, Carboxypeptidase N subunit 2, Polyadenylate-binding protein 4, Septin-13, Zinc finger protein 189, Leucine-rich glioma-inactivated protein 1, Uncharacterized protein KIAA0552, Transthyretin, Inter-alpha-trypsin inhibitor heavy chain HI,

Ig mu heavy chain, Ubiquilin-3, Serine/threonine-protein kinase PDIK1L,

Complement C2, T-cell surface glycoprotein CDlb and Vitamin D-binding protein as a specific panel of analyte biomarkers for schizophrenia or other psychotic disorder, or predisposition thereto.

6. Use of Apolipoprotein C-II, Lumican, Apolipoprotein B-100, Fetuin-B, Thrombospondin-4, EGF-containing fibulin-like extracellular matrix protein 1, Beta-l,4-galactosyltransferase 3, 60S ribosomal export protein NMD3,

Complement factor H, Structural maintenance of chromosomes protein 4, Kinesin-like protein KIF16B, Myelin protein PO, Forkhead box protein P3, NACHT LRR and PYD domains-containing protein 14, Apolipoprotein A-IV, Protein CLN8, Apolipoprotein C-III, Proteasome subunit alpha type-2, Glycosyltransferase-like protein LARGEl, Collagen alpha-l(XXII) chain, Sulfhydryl oxidase 1, RING finger protein 214, Alpha-2-HS-glycoprotein, Plasma protease CI inhibitor,

Apolipoprotein(a), Properdin, Complement factor H-related protein 1,

Apolipoprotein C-I, Apolipoprotein E, Platelet basic protein, Paxillin,

Angiotensinogen, Clusterin, Complement component C8 beta chain, Pigment epithelium-derived factor, CD5 antigen-like, Complement Clr subcomponent, Keratin type I cytoskeletal 10, Biotinidase, Apolipoprotein M, Pregnancy zone protein, F-box only protein 11, AP20 region protein 1, Gelsolin, Cold shock domain-containing protein El, KH domain-containing RNA-binding signal transduction-associated protein 1, Keratin type I cytoskeletal 26, Ig mu chain C region, Complement component C7 and Synaptophysin-like protein 1 as a specific panel of analyte biomarkers for schizophrenia or other psychotic disorder, or predisposition thereto.

7. A method of diagnosing schizophrenia or other psychotic disorder, or predisposition in an individual thereto, comprising :

(a) quantifying the amounts of the analyte biomarkers as defined in any of claims 1 to 6 in a biological sample obtained from an individual;

(b) comparing the amounts of the analyte biomarkers in the biological sample with the amounts present in a normal control biological sample from a normal subject, such that a difference in the level of the analyte biomarkers in the biological sample is indicative of schizophrenia or other psychotic disorder, or predisposition thereto.

8. A method of monitoring efficacy of a therapy in a subject having, suspected of having, or of being predisposed to schizophrenia or other psychotic disorder, comprising detecting and/or quantifying, in a sample from said subject, the analyte biomarkers as defined in any of claims 1 to 6.

9. A method as defined in claim 7 or claim 8, which is conducted on samples taken on two or more occasions from a test subject.

10. A method as defined in any of claims 7 to 9, further comprising comparing the level of the biomarker present in samples taken on two or more occasions.

11. A method as defined in any of claims 7 to 10, comprising comparing the amount of the biomarker in said test sample with the amount present in one or more samples taken from said subject prior to commencement of therapy, and/or one or more samples taken from said subject at an earlier stage of therapy.

12. A method as defined in any of claims 7 to 11, further comprising detecting a change in the amount of the biomarker in samples taken on two or more occasions.

13. A method as defined in any of claims 7 to 12, comprising comparing the amount of the biomarker present in said test sample with one or more controls.

14. A method as defined in claim 13, comprising comparing the amount of the biomarker in a test sample with the amount of the biomarker present in a sample from a normal subject.

15. A method as defined in any of claims 7 to 14, wherein samples are taken prior to and/or during and/or following therapy for schizophrenia or other psychotic disorder.

16. A method as defined in any of claims 7 to 15, wherein samples are taken at intervals over the remaining life, or a part thereof, of a subject.

17. A method as defined in any of claims 7 to 16, wherein quantifying is performed by measuring the concentration of the analyte biomarker in the or each sample.

18. A method for classifying a psychotic patient, such as a schizophrenia patient, as a responder or non-responder to antipsychotic therapy, such as schizophrenia therapy, comprising the steps of:

(a) quantifying the amounts of the analyte biomarkers as defined in any of claims 1 to 6 in a test biological sample obtained from the patient; and

(b) classifying the patient as a responder or non-responder to anti psychotic therapy based on the expression levels of the analyte biomarkers.

19. A method for monitoring patient compliance with antipsychotic therapy, such as schizophrenia therapy, comprising the steps of:

(a) quantifying the amounts of the analyte biomarkers as defined in any of claims 1 to 6 in a test biological sample obtained from the patient prior to commencement of antipsychotic therapy; and

(b) comparing the amounts of the analyte biomarkers in the biological sample with the amounts present in a biological sample obtained from the patient after commencement of antipsychotic therapy, such that a difference in the level of the analyte biomarkers in the biological sample is indicative of patient compliance with antipsychotic therapy.

20. A method as defined in any of claims 7 to 19, wherein detecting and/or quantifying is performed by one or more methods selected from SELDI (-TOF), MALDI (-TOF), a 1-D gel-based analysis, a 2-D gel-based analysis, Mass spec (MS), reverse phase (RP) LC, size permeation (gel filtration), ion exchange, affinity, HPLC, UPLC or other LC or LC-MS-based technique.

21. A method as defined in any of claims 7 to 20, wherein detecting and/or quantifying is performed using an immunological method.

22. A method as defined in any of claims 7 to 21, wherein the detecting and/or quantifying is performed using a biosensor or a microanalytical, microengineered, microseparation or immunochromatography system.

23. A method as defined in any of claims 7 to 22, wherein the biological sample is cerebrospinal fluid, whole blood, blood serum, plasma, urine, saliva, or other bodily fluid, or breath, condensed breath, or an extract or purification therefrom, or dilution thereof.

24. A kit for monitoring or diagnosing schizophrenia or other psychotic disorder, comprising a biosensor capable of detecting and/or quantifying the analyte biomarkers as defined in any of claims 1 to 6.