Applications of pharmacogenetics in psychiatry: personalisation of treatment

The socio-economical burden of schizophrenia: A simulation of cost-offset of early intervention program in Italy

Schizophrenia is associated with a high familiar, social and economic burden. During the recent years early and specific intervention for first psychotic episodes has been suggested to improve the long term outcome of the disease. Despite the promising results obtained so far, early intervention is still scarcely applied. One major problem arises from the translation of research findings into stakeholder policies. In fact very few analyses of cost reductions obtained with early intervention have been reported. In the present paper we present a simulation of direct cost reduction that can be obtained with early intervention programmes. We based our analysis on available data about schizophrenia care costs in Italy and the expected cost reduction with the use of early intervention. We observed that the increase in costs due to the more intensive early intervention is largely compensated by the reduction of inpatient admissions with a reduction of direct costs of 6.01%. Despite the apparently small economic gain, early intervention offers more clinical and social benefits as it seems to be effective also in decreasing relapse rates, in improving the patients' quality of life and disability associated with psychosis and in increasing employment rates. Those indirect costs however are difficult to estimate and were not included in our model.

In conclusion, our study supports the use of early intervention in schizophrenia, which could allow an outcome improvement with lower direct and indirect costs.

Clinical application of genomic high-throughput data: Infrastructural, ethical, legal and psychosocial aspects

Genomic high-throughput technologies (GHTT) such as next-generation sequencing represent a fast and cost-effective tool toward a more comprehensive understanding of the molecular background of complex diseases. However, technological advances contrast with insufficient application in clinical practice. Thus, patients, physicians, and other professionals are faced with tough challenges that forestall the efficient and effective implementation. With the increasing application of genetic testing, it is of paramount importance that physicians and other professionals in healthcare recognize the restrictions and potential of GHTT, in order to understand and interpret the complex data in the context of health and disease. At the same time, the growing volume and complexity of data is forever increasing the need for sustainable infrastructure and state-of-the-art tools for efficient data management, including their analysis and integration. The large pool of sensitive information remains difficult to interpret and fundamental questions spanning from billing to legal, social, and ethical issues have still not been resolved. Here we summarize and discuss these obstacles in an interdisciplinary context and suggest ways to overcome them. Continuous discussion with clinicians, data managers, biostatisticians, systems medicine experts, ethicists, legal scholars, and patients illuminates the strengths, weakness, and current practices in the pipeline from biomaterial to sequencing and data management. This discussion also highlights the new, cross-disciplinary working collaborations to realize the wide-ranging challenges in clinical genomics including the exceptional demands placed on the staff preparing and presenting the data, as well as the question as to how to report the data and results to patients.

Pharmacogenetics: Policy needs for personal prescribing

Pharmacogenetics involves genetic testing of individual patients to guide drug treatment. Proponents argue that pharmacogenetics will achieve major gains in drug safety and efficacy, and revolutionise marketing. Pharmacogenetics also raises several policy concerns, including the need for sound information for clinical decision-making on drug-genetic test combinations. Currently, the pharmacogenetics science base and the rate of emergence of clinical applications are uncertain. Most commentary on pharmacogenetics focuses on new compounds, yet older drugs cause most adverse events. Test regulation in the USA appears fundamentally different from Europe, where evidence of safety or efficacy may not be required. Genetics research is needed as part of postmarketing surveillance systems. In routine clinical practice, computer-based health records with relevant decision support systems will also be needed. Without health policy action, pharmacogenetics could produce a new generation of poorly evaluated tests and drugs, with medicine becoming significantly less evidence-based, leading to rising costs, patient hazard and exclusions of drug-related ‘genetic minorities’ from evaluated treatments.

Novel drug metabolism indices for pharmacogenetic functional status based on combinatory genotyping of CYP2C9, CYP2C19 and CYP2D6 genes

AIMS

We aim to demonstrate clinical relevance and utility of four novel drug-metabolism indices derived from a combinatory (multigene) approach to CYP2C9, CYP2C19 and CYP2D6 allele scoring. Each index considers all three genes as complementary components of a liver enzyme drug metabolism system and uniquely benchmarks innate hepatic drug metabolism reserve or alteration through CYP450 combinatory genotype scores.

METHODS

A total of 1199 psychiatric referrals were genotyped for polymorphisms in the CYP2C9, CYP2C19 and CYP2D6 gene loci and were scored on each of the four indices. The data were used to create distributions and rankings of innate drug metabolism capacity to which individuals can be compared. Drug-specific indices are a combination of the drug metabolism indices with substrate-specific coefficients.

RESULTS

The combinatory drug metabolism indices proved useful in positioning individuals relative to a population with regard to innate drug metabolism capacity prior to pharmacotherapy. Drug-specific indices generate pharmacogenetic guidance of immediate clinical relevance, and can be further modified to incorporate covariates in particular clinical cases.

CONCLUSIONS

We believe that this combinatory approach represents an improvement over the current gene-by-gene reporting by providing greater scope while still allowing for the resolution of a single-gene index when needed. This method will result in novel clinical and research applications, facilitating the translation from pharmacogenomics to personalized medicine, particularly in psychiatry where many drugs are metabolized or activated by multiple CYP450 isoenzymes.

Pharmacogenetic testing in psychiatry: a review of features and clinical realities

This article focuses on the first generation of pharmacogenetic tests that are potentially useful in psychiatry. All pharmacogenetic tests currently on the market, or soon to be marketed in psychiatry, for which some information has been published in peer-reviewed journal articles (or abstracts), were selected. Five pharmacogenetic tests are reviewed in detail: the Roche AmpliChip CYP450 Test, the Luminex Tag-It Mutation Detection Kit, the LGC clozapine response test, the PGxPredict: Clozapine test, and the Genomas PhyzioType system. After reviewing these tests, three practical aspects of implementing pharmacogenetic testing in psychiatric clinical practice are briefly reviewed: (1) the evaluation of these tests in clinical practice, (2) cost-effectiveness, and (3) regulatory oversight. Finally, the future of these and other pharmacogenetic tests in psychiatry is discussed.

G-protein gene 825C>T polymorphism is associated with response to clozapine in Brazilian schizophrenics

AIMS

Clozapine treatment of schizophrenia is effective only in 30-60% of individuals. Since genetic factors are believed to play a significant role in the variation of response to antipsychotics, the aim of the present study was to verify the effect of a G-protein gene polymorphism on clozapine response and clozapine-induced generalized seizures in Brazilian patients with schizophrenia.

PATIENTS & METHODS

In total, 121 schizophrenic patients in treatment with clozapine were genotyped for the 825C>T polymorphism it the GNB3 gene using PCR.

RESULTS

Homozygosity for the T825 allele was more frequent among nonresponders (chi(2) = 7.708; p = 0.021), and carriers of this allele had a higher risk to present a convulsion episode (chi(2) = 7.279; p = 0.007). These results were confirmed after controlling for covariates by logistic regression.

CONCLUSION

Our data suggest an influence of the 825C>T polymorphism on clozapine response in persons with schizophrenia and also on a specific neurological side effect (generalized seizures) under clozapine treatment.

Pharmacogenetics of antiparkinsonian drug treatment: a systematic review

Pharmacotherapy is the mainstay in the treatment of Parkinson's disease and the armamentarium of drugs available for the therapy of this disease is still expanding. Anti-Parkinson's disease drugs are effective in reducing the physical symptoms, such as hypokinesia, bradykinesia, rigidity and tremor. However, there is a large interindividual variability in response to anti-Parkinson's disease drugs with respect to both drug efficacy and toxicity. It is thought that genetic variability in genes encoding drug-metabolizing enzymes, drug receptors and proteins involved in pathway signaling is an important factor in determining interindividual variability in drug response. Pharmacogenetics aims at identifying genetic markers associated with drug response. Ideally, knowledge of these genetic markers will enable us to predict an individual's drug response in terms of both efficacy and toxicity. The role of pharmacogenetics in the treatment of Parkinson's disease is relatively unexplored. Therefore, we aim to present a systematic review of the published pharmacogenetic studies in Parkinson's disease and to describe polymorphic genes of interest for future research.

Neural network analysis in pharmacogenetics of mood disorders

Background

The increasing number of available genotypes for genetic studies in humans requires more advanced techniques of analysis. We previously reported significant univariate associations between gene polymorphisms and antidepressant response in mood disorders. However the combined analysis of multiple gene polymorphisms and clinical variables requires the use of non linear methods.

Methods

In the present study we tested a neural network strategy for a combined analysis of two gene polymorphisms. A Multi Layer Perceptron model showed the best performance and was therefore selected over the other networks. One hundred and twenty one depressed inpatients treated with fluvoxamine in the context of previously reported pharmacogenetic studies were included. The polymorphism in the transcriptional control region upstream of the 5HTT coding sequence (SERTPR) and in the Tryptophan Hydroxylase (TPH) gene were analysed simultaneously.

Results

A multi layer perceptron network composed by 1 hidden layer with 7 nodes was chosen. 77.5 % of responders and 51.2% of non responders were correctly classified (ROC area = 0.731 – empirical p value = 0.0082). Finally, we performed a comparison with traditional techniques. A discriminant function analysis correctly classified 34.1 % of responders and 68.1 % of non responders (F = 8.16 p = 0.0005).

Conclusions

Overall, our findings suggest that neural networks may be a valid technique for the analysis of gene polymorphisms in pharmacogenetic studies. The complex interactions modelled through NN may be eventually applied at the clinical level for the individualized therapy.

The role of atypical antipsychotics in glucose/insulin dysregulation and the evolving role of the psychiatrist in a new era of drug treatment options

This article examines the issue of atypical antipsychotics, glucose/insulin, and other metabolic derangements (ie, metabolic syndrome), including a general introduction to the health concerns of our patients, a review of the literature, possible mechanisms of antipsychotic induced glucose dysregulation, monitoring approaches, and management and prevention of metabolic syndrome. Literature review leads to mechanism hypotheses and risk estimations, leading to guidelines for monitoring and treatment. The patient population suffers from a higher degree of baseline metabolic dysregulation resulting in cardiovascular disease through components of the metabolic syndrome, and this risk increases with administration of atypical antipsychotic medication at different rates, depending on both drug and patient risk factors. The growing knowledge of mechanisms behind drug induced glucose/insulin and other metabolic dysregulation, as well as advances in pharmacogenomics, will help refine drug selection and monitoring for adverse, life-threatening metabolic effects.

Using pharmacogenetics and pharmacogenomics in the treatment of psychiatric disorders: some ethical and economic considerations

Current pharmacotherapies for psychiatric disorders are generally incompletely effective. Many patients do not respond well or suffer adverse reactions to these drugs, which can result in poor patient compliance and poor treatment outcome. Adverse drug reactions and non-response are likely to be influenced by genetic polymorphisms. Pharmacogenetics holds some promise for improving the treatment of mood disorders by utilising information about genetic polymorphisms to match patients to the drug therapy that is the most effective with the fewest side effects. Pharmacogenomics promises to facilitate the development of new drugs for treatment. However, these technologies raise many ethical, economic and regulatory issues that need to be addressed before they can be integrated into psychiatry, and medicine more generally. We discuss ethical and policy issues arising from pharmacogenetic testing and pharmacogenomics research, such as informed consent, privacy and confidentiality, research on vulnerable persons and discrimination; and economic viability of pharmacogenetics and pharmacogenomics. We conclude with recommendations for the regulation and distribution of pharmacogenetic testing services and pharmacogenomic drugs.

Human genetic variations in the 5HT2A receptor: a single nucleotide polymorphism identified with altered response to clozapine

OBJECTIVE

to determine if the agonist serotonin and antagonists loxapine and clozapine have an altered potency for four allelic variants (T25N, I197V, A447V, and H452Y) of the human 5HT2A receptor when compared to the wild-type allele.

METHODS

The receptor or its variants are studied in an in-vitro functional assay system consisting of a Sf9 insect cell line that is stably transformed with the human wild-type and mutant alleles. This assay system measures release of calcium stores due to receptor activation by agonists and inhibition of this agonist stimulated response by antagonists.

RESULTS

Both loxapine and clozapine exhibit non-competitive antagonism of serotonin stimulation of the human 5HT2A receptor signal transduction system and loxapine is the more potent inhibitor. This study shows that the I197V allele requires a two-fold higher concentration of the atypical neuroleptic clozapine to inhibit serotonin stimulation compared to the wild-type receptor (P = 0.036). The I197V mutation does not affect the inhibition of serotonin stimulation by the typical neuroleptic loxapine nor does it alter the activation of the receptor by serotonin. It is also significant that the results of this study indicate that the T25N, A447V, and H452Y mutations in the human 5HT2A receptor do not significantly alter the response of the receptor to the agonist serotonin or the antagonists loxapine and clozapine.

Psychopharmacogenetics--a challenge for pharmacotherapy in psychiatry

Differences in response to treatment or the incidence of adverse drug effects are quite common in clinical psychopharmacotherapy. Although several factors may account for these discrepancies, there is increasing knowledge that genetic factors play a major role. The aim of pharmacogenetics, a new and rapidly growing field in research, is to elucidate the variability in drug response and metabolism due to hereditary differences. According to the hypotheses on the mechanisms of drug action, several mutations in genes coding for neurotransmitter receptors, degrading enzymes, transport proteins or enzymes of the drug metabolizing system (P-450 isoenzymes) have been identified and investigated in psychiatric disorders over the last years. Although some controversy exists among the results, many studies are supportive of the hypothesis that psychopharmacogenetics will be helpful in predicting an individual patient's drug response while minimising the rate of side effects.