Integrating pharmacogenomics into drug development

Implementing pharmacogenetics in clinical trials: considerations about current methodological, ethical, and regulatory challenges

INTRODUCTION

The implementation of pharmacogenetic analysis within clinical trials faces methodological, ethical, and regulatory challenges, as well as tackling the difficulty in obtaining actionable information with a sufficient level of evidence to enable its integration into routine clinical practice.

AREAS COVERED

We discuss the current status of pharmacogenetics integration in clinical trials, underscore the associated challenges, and make some suggestions on the aspects to address in any clinical trial including a pharmacogenetic evaluation. We conducted a literature review, thoroughly reviewed the applicable regulations and available guidelines, and assessed the application dossiers submitted for evaluation to the Ethics committee of Hospital La Paz (Madrid, Spain) to extract information related to inclusion of pharmacogenetics evaluations.

EXPERT OPINION

The integration of pharmacogenetics into clinical trials is becoming increasingly common. However, several regulatory, methodological and ethical aspects involved are insufficiently addressed. There is a need for specific and transparent guidelines that establish unified and compliant criteria for methodology, proper handling of samples in compliance with regulations, and the protection of data privacy and confidentiality. Participants should receive complete and appropriate information regarding the purpose, handling, storage, and transfer of their samples and data, and should have the right to decide about their processing.

Pharmacogenomics in early-phase clinical development

Pharmacogenomics (PGx) offers the promise of utilizing genetic fingerprints to predict individual responses to drugs in terms of safety, efficacy and pharmacokinetics. Early-phase clinical trial PGx applications can identify human genome variations that are meaningful to study design, selection of participants, allocation of resources and clinical research ethics. Results can inform later-phase study design and pipeline developmental decisions. Nevertheless, our review of the clinicaltrials.gov database demonstrates that PGx is rarely used by drug developers. Of the total 323 trials that included PGx as an outcome, 80% have been conducted by academic institutions after initial regulatory approval. Barriers for the application of PGx are discussed. We propose a framework for the role of PGx in early-phase drug development and recommend PGx be universally considered in study design, result interpretation and hypothesis generation for later-phase studies, but PGx results from underpowered studies should not be used by themselves to terminate drug-development programs.

A unified framework for the evaluation of surrogate endpoints in mental-health clinical trials

For a number of reasons, surrogate endpoints are considered instead of the so-called true endpoint in clinical studies, especially when such endpoints can be measured earlier, and/or with less burden for patient and experimenter. Surrogate endpoints may occur more frequently than their standard counterparts. For these reasons, it is not surprising that the use of surrogate endpoints in clinical practice is increasing. Building on the seminal work of Prentice(1) and Freedman et al.,(2) Buyse et al. (3) framed the evaluation exercise within a meta-analytic setting, in an effort to overcome difficulties that necessarily surround evaluation efforts based on a single trial. In this article, we review the meta-analytic approach for continuous outcomes, discuss extensions to non-normal and longitudinal settings, as well as proposals to unify the somewhat disparate collection of validation measures currently on the market. Implications for design and for predicting the effect of treatment in a new trial, based on the surrogate, are discussed. A case study in schizophrenia is analysed.

Pharmacogenomics: the promise of personalized medicine for CNS disorders

This review focuses first on the concept of pharmacogenomics and its related concepts (biomarkers and personalized prescription). Next, the first generation of five DNA pharmacogenomic tests used in the clinical practice of psychiatry is briefly reviewed. Then the possible involvement of these pharmacogenomic tests in the exploration of early clinical proof of mechanism is described by using two of the tests and one example from the pharmaceutical industry (iloperidone clinical trials). The initial attempts to use other microarray tests (measuring RNA expression) as peripheral biomarkers for CNS disorders are briefly described. Then the challenge of taking pharmacogenomic tests (compared to drugs) into clinical practice is explained by focusing on regulatory oversight, the methodological/scientific issues concerning diagnostic tests, and cost-effectiveness issues. Current information on medicine-based evidence and cost-effectiveness usually focuses on average patients and not the outliers who are most likely to benefit from personalized prescription. Finally, future research directions are suggested. The future of 'personalized prescription' in psychiatry requires consideration of pharmacogenomic testing and environmental and personal variables that influence pharmacokinetic and pharmacodynamic drug response for each individual drug used by each patient.

Influence of ovarian hormones deprivation on gene expression in the lower urinary tract of rats

OBJECTIVE

Identify the influence of ovarian hormone deprivation in expression genes on the lower urinary tract of rats.

MATERIALS AND METHODS

This study deals with gene screening on lower urinary tract of rats. Fifty isogenic rats divided in two groups of twenty-five animals have their lower urinary tract surgically removed: group I, ovariectomized rats 30 days prior to surgery; group II, non-ovariectomized rats. Total RNA was isolated from bladder and urethra, and differential expression of genes was analyzed quantitative, qualitative and comparatively by array technology and RT-PCR.

RESULTS

A total of 76 candidate genes were identified as differentially expressed between the groups, 26 being lower expressed in group II, and 50 in group I. Among them, differential expression validation was confirmed by RT-PCR for three lower expressed genes in group I: Vascular Endothelial Growth Factor (VEGF), Beta-2 Microglobulin (B2M) and Cytochrome c Oxidase subunit I (COX I).

CONCLUSION

Ovarian hormone deprivation influences the expression genes on lower urinary tract. We demonstrated that a 30-day period of castration down regulate the expression of VEGF, B2M and COX I in adult rats which are involved in activities of angiogenesis, immune responses and cellular metabolism respectively.

A perspective on surrogate endpoints in controlled clinical trials

The last couple of decades have seen a large amount of activity in the area of surrogate marker and surrogate endpoint validation, both from a clinical and a statistical perspective. Prentice made a pivotal contribution in the context of a single trial. Subsequently, the framework he proposed has been discussed, criticized, and extended. An important class of extensions considers several rather than a single trial. Recently, a lot of work has been done in this so-called hierarchical or meta-analytic framework. In this paper, we review both the single trial and the hierarchical framework. A number of applications, scattered throughout the literature, are brought together. We outline the statistical issues involved in trying to validate surrogate endpoints. Clearly statistical evidence should only be seen as a component in a decision making process that also involves a number of clinical and biological considerations.

Antibiotics and pharmacogenomics

The widespread use of antibiotics impacts both the bacterial ecology and the host at multiple levels, both advantageously and deleteriously. Since serious bacterial infection can lead to death in the absence of antibiotic therapy, antibiotics remain a necessary weapon in the clinician's arsenal for maintaining good health. It is thus critical that the placement and usage of these crucial antibiotics be constantly improved, and that emerging antibiotic resistance is vigorously assessed. To realize both these ends, it may be valuable to turn to the discipline of pharmacogenomics and develop it for use in a fairly novel way, that is, as the means by which to determine and analyze the impact of antibiotic therapy on both the pathogen and host.