Pharmacogenetics, Pharmacogenomics and Personalized Medicine: Are We There Yet?

Empowering precision medicine: Insights from a national survey on pharmacogenomics knowledge, attitudes, and perceptions among community pharmacists in the UAE

Background

Community pharmacists are essential to pharmacogenomics implementation because they can help trainers, clinical advisors, and other medical professionals understand the importance of pharmacogenomics and encourage them to use it in their practice. This study is to evaluate the community pharmacists' understanding, attitudes, and perceptions of pharmacogenomics in the United Arab Emirates (UAE).

Methods

Professionals employed at community pharmacies in Abu Dhabi, Dubai, and the Northern Emirates participated in a cross-sectional study design. From July 2023 to February 2024, five pharmacy students in their last year conducted the survey. The study team employed a structured questionnaire to collect data in addition to conducting in-person interviews. The study questionnaire comprised three distinct sections namely, demographic information, knowledge of pharmacogenomics concepts, and perceptions regarding pharmacogenomics.

Results

A total of 586 pharmacists enrolled in the study. The average knowledge score regarding pharmacogenomics was 75.1 % with a 95 % confidence interval (CI) of [72.4 %, 77.7 %]. The average attitude score toward pharmacogenomics was 67.5 % with a 95 % CI of [66.3 %, 68.7 %]. Better pharmacogenomics knowledge among several groups: independent pharmacies (OR 1.7; 95 % CI 1.2-2.4), Pharmacists in Charge (OR 1.4; 95 % CI 1.3-2.02), pharmacists with 11-15 years of experience (OR 2.1; 95 % CI 1.4-4.2), graduates from international universities (OR 4.6; 95 % CI 1.6-12.9), and those who received training on pharmacogenomics (OR 11.9; 95 % CI 3.3-14.5). Similarly, better attitude scores were observed among independent pharmacies (OR 1.5; 95 % CI 1.1-2.1), Pharmacists in Charge (OR 1.5; 95 % CI 1.07-2.1), pharmacists with 16-20 years of experience (OR 2.1; 95 % CI 1.16-3.7), graduates regional universities (OR 1.47; 95 % CI 1.05-2.1), and those who received training on pharmacogenomics (OR 4.8; 95 % CI 3.2-7.3).

Conclusion

The positive attitudes toward pharmacogenomics that we found in our research indicate that community pharmacists in the United Arab Emirates are beginning to realize the potential advantages of pharmacogenomics in terms of improving patient care. Policies ensuring the privacy and confidentiality of genetic information are also necessary in considering concerns about the availability of genetic test results to insurance companies and potential employers.

Pharmacists' Knowledge, and Insights in Implementing Pharmacogenomics in Saudi Arabia

BACKGROUND

Pharmacogenomics (PGx) and personalized medicine embrace the potential to optimize drug treatment and improve the patient's quality of life. Pharmacists' roles include contributing to genetic testing, patient counseling, and pharmacotherapies selection for superior treatment outcomes. The aim of this study is to assess the pharmacists' knowledge, insight, and self-confidence toward PGx testing, identify their future preferred education patterns, and determine the barriers to pharmacogenomic testing implementation.

METHOD

A cross-sectional study was conducted using a previously validated questionnaire among pharmacists working in the Kingdom of Saudi Arabia (KSA). The questionnaire was designed in seven major categories, consisting of 26 questions.

RESULTS

A total of 671 pharmacists participated in this survey. As for knowledge, only 29.8% of pharmacists had good knowledge regarding PGx, while 42.9% had poor knowledge levels. Respectable PGx knowledge was significantly higher among outpatient dispensing pharmacists (33.6%; p = 0.049) and among pharmacists who had completed PGx testing-related training or education (40.3%; p = 0.001). Considering perception, it was positive among 50% of pharmacists and negative among 19.8%. With regard to self-confidence, it was high among 39.2% of male pharmacists (p = 0.042), among 43% of clinical pharmacists (p = 0.006), and among 44.8% of pharmacists who had extra credentials (p = 0.001). The utmost favored continuing-education learning approaches were workshops or seminars. The barriers to the implementation of PGx testing included a lack of testing devices, clinical guidelines, training or education, and personnel.

CONCLUSION

The present study revealed that pharmacists in KSA had inadequate knowledge and understanding of PGx. Nevertheless, the majority established that PGx is a valuable tool for augmenting drug efficacy and safety.

Knowledge, Attitude and Perception of Pharmacy Students towards Pharmacogenomics and Genetics: An Observational Study from King Saud University

Pharmacists are considered among the most accessible healthcare workers in fundamental positions to implement new clinical initiatives, such as pharmacogenomics services. The scope of pharmacogenomics in improving health outcomes and the quality of health care is well-known. Implementation of such initiatives requires adequate knowledge, perception, and positive attitudes among pharmacists. A study was conducted on pharmacy students at King Saud University in Riyadh to analyze their attitudes, knowledge, and perceptions concerning pharmacogenomics to explore the feasibility of establishing full-time pharmacogenomics instruction and services. A cross-sectional study was carried out in one of the significant pharmacy schools of Saudi Arabia, using a simple questionnaire-based survey in pharmacy students pursuing Bpharm and PharmD courses to obtain preliminary information about pharmacogenomics among the surveyed population. The study's secondary objective was to determine the perceived belief about pharmacogenomics implementation in clinical practice. Out of the total of 552 participants, 41.8% correctly defined pharmacogenomics and 81.3% understood that genetic change could lead to adverse reactions. More than half of the participants agreed that the FDA recommends pharmacogenomics testing for certain drugs. The knowledge about a year of use of pharmacogenomics in clinical practice was found to be very low; only 15.2% could correctly answer. Only 60% of students agreed on pharmacogenomics testing for selecting the therapy with the most negligible adverse effects. Due to the limited knowledge about and understanding of pharmacogenomics, there is a lack of interest among pharmacy students in implementing pharmacogenomics testing in clinical practice. Our study highlights the need for improving pharmacy students' knowledge about pharmacogenomics and pharmacogenetics so that the implementation of pharmacogenomics testing in clinical practice will become easier. There is a need to introduce an up-to-date curriculum for pharmacy courses other pharmacogenomics-based health education programs in Saudi Arabia.

Response and Toxicity to Cytarabine Therapy in Leukemia and Lymphoma: From Dose Puzzle to Pharmacogenomic Biomarkers

Simple Summary

In this review, the authors propose a crosswise examination of cytarabine-related issues ranging from the spectrum of clinical activity and severe toxicities, through updated cellular pharmacology and drug formulations, to the genetic variants associated with drug-induced phenotypes. Cytarabine (cytosine arabinoside; Ara-C) in multiagent chemotherapy regimens is often used for leukemia or lymphoma treatments, as well as neoplastic meningitis. Chemotherapy regimens can induce a suboptimal clinical outcome in a fraction of patients. The individual variability in clinical response to Leukemia & Lymphoma treatments among patients appears to be associated with intracellular accumulation of Ara-CTP due to genetic variants related to metabolic enzymes. The review provides exhaustive information on the effects of Ara-C-based therapies, the adverse drug reaction will also be provided including bone pain, ocular toxicity (corneal pain, keratoconjunctivitis, and blurred vision), maculopapular rash, and occasional chest pain. Evidence for predicting the response to cytarabine-based treatments will be highlighted, pointing at their significant impact on the routine management of blood cancers.

Abstract

Cytarabine is a pyrimidine nucleoside analog, commonly used in multiagent chemotherapy regimens for the treatment of leukemia and lymphoma, as well as for neoplastic meningitis. Ara-C-based chemotherapy regimens can induce a suboptimal clinical outcome in a fraction of patients. Several studies suggest that the individual variability in clinical response to Leukemia & Lymphoma treatments among patients, underlying either Ara-C mechanism resistance or toxicity, appears to be associated with the intracellular accumulation and retention of Ara-CTP due to genetic variants related to metabolic enzymes. Herein, we reported (a) the latest Pharmacogenomics biomarkers associated with the response to cytarabine and (b) the new drug formulations with optimized pharmacokinetics. The purpose of this review is to provide readers with detailed and comprehensive information on the effects of Ara-C-based therapies, from biological to clinical practice, maintaining high the interest of both researcher and clinical hematologist. This review could help clinicians in predicting the response to cytarabine-based treatments.

Pharmacogenetic and pharmacogenomic considerations of asthma treatment

INTRODUCTION

Pharmacogenetic and pharmacogenomic approaches are already utilized in some areas, such as oncology and cardiovascular disease, for selecting appropriate patients and/or establishing treatment and dosing guidelines. This is not true in asthma although many patients have different responses to drug treatment due to genetic factors. Areas covered: Several genetic factors that affect the pharmacotherapeutic responses to asthma medications, such as β₂-AR agonists, corticosteroids, and leukotriene modifiers and could contribute to significant between-person variability in response are described. Expert opinion: An expanding number of genetic loci have been associated with therapeutic responses to asthma drugs but the individual effect of one single-nucleotide polymorphism is partial. In fact, epigenetic changes can modify genetic effects in time-, environment-, and tissue-specific manners, genes interact together in networks, and nongenetic components such as environmental exposures, gender, nutrients, and lifestyle can significantly interact with genetics to determine the response to therapy. Therefore, well-designed randomized controlled trials or observational studies are now mandatory to define if response to asthma medications in individual patients can be improved by using pharmacogenetic predictors of treatment response. Meanwhile, routine implementation of pharmacogenetics and pharmacogenomics into clinical practice remains a futuristic, far-off challenge for many clinical practices.

Research and Discovery Science and the Future of Dental Education and Practice

Dental graduates of 2040 will face new and complex challenges. If they are to meet these challenges, dental schools must develop a research and discovery mission that will equip graduates with the new knowledge required to function in a modern health care environment. The dental practitioner of 2040 will place greater emphasis on risk assessment, disease prevention, and health maintenance; and the emerging discipline of precision medicine and systems biology will revolutionize disease diagnosis and reveal new targeted therapies. The dental graduate of 2040 will be expected to function effectively in a collaborative, learning health care system and to understand the impact of health care policy on local, national, and global communities. Emerging scientific fields such as big data analytics, stem cell biology, tissue engineering, and advanced biomimetics will impact dental practice. Despite all the warning signs indicating how the changing scientific and heath care landscape will dramatically alter dental education and dental practice, dental schools have yet to reconsider their research and educational priorities and clinical practice objectives. Until dental schools and the practicing community come to grips with these challenges, this persistent attitude of complacency will likely be at the dental profession's peril. This article was written as part of the project "Advancing Dental Education in the 21^st Century."

Model-Based Individualized Treatment of Chemotherapeutics: Bayesian Population Modeling and Dose Optimization

6-Mercaptopurine (6-MP) is one of the key drugs in the treatment of many pediatric cancers, auto immune diseases and inflammatory bowel disease. 6-MP is a prodrug, converted to an active metabolite 6-thioguanine nucleotide (6-TGN) through enzymatic reaction involving thiopurine methyltransferase (TPMT). Pharmacogenomic variation observed in the TPMT enzyme produces a significant variation in drug response among the patient population. Despite 6-MP's widespread use and observed variation in treatment response, efforts at quantitative optimization of dose regimens for individual patients are limited. In addition, research efforts devoted on pharmacogenomics to predict clinical responses are proving far from ideal. In this work, we present a Bayesian population modeling approach to develop a pharmacological model for 6-MP metabolism in humans. In the face of scarcity of data in clinical settings, a global sensitivity analysis based model reduction approach is used to minimize the parameter space. For accurate estimation of sensitive parameters, robust optimal experimental design based on D-optimality criteria was exploited. With the patient-specific model, a model predictive control algorithm is used to optimize the dose scheduling with the objective of maintaining the 6-TGN concentration within its therapeutic window. More importantly, for the first time, we show how the incorporation of information from different levels of biological chain-of response (i.e. gene expression-enzyme phenotype-drug phenotype) plays a critical role in determining the uncertainty in predicting therapeutic target. The model and the control approach can be utilized in the clinical setting to individualize 6-MP dosing based on the patient's ability to metabolize the drug instead of the traditional standard-dose-for-all approach.

Should we keep on? Looking into pharmacogenomics of ADHD in adulthood from a different perspective

A considerable proportion of adults with attention-deficit/hyperactivity disorder (ADHD) do not respond to the treatment with methylphenidate. This scenario could be due to inherited interindividual differences that may alter pharmacologic treatment response. In this sense, in 2012 we conducted a systematic search on PUBMED-indexed literature for articles containing information about pharmacogenomics of ADHD in adults. Five studies were found on methylphenidate pharmacogenomics and the only significant association was reported by one particular study. However, this single association with the SLC6A3 gene was not replicated in two subsequent reports. In the present review, although we could not find additional pharmacogenomics studies, we discuss these up-to-date findings and suggest new approaches for this field. Additionally, using systeomic-oriented databases, we provide a broad picture of new possible candidate genes as well as potential gene-gene interactions to be investigated in pharmacogenomics of persistent ADHD.

Revitalizing personalized medicine: respecting biomolecular complexities beyond gene expression

Despite recent advancements in "omic" technologies, personalized medicine has not realized its fullest potential due to isolated and incomplete application of gene expression tools. In many instances, pharmacogenomics is being interchangeably used for personalized medicine, when actually it is one of the many facets of personalized medicine. Herein, we highlight key issues that are hampering the advancement of personalized medicine and highlight emerging predictive tools that can serve as a decision support mechanism for physicians to personalize treatments.

Clinical characteristics, response to therapy, and survival of African American patients diagnosed with chronic lymphocytic leukemia: joint experience of the MD Anderson Cancer Center and Duke University Medical Center

BACKGROUND

Little is known regarding racial disparities in characteristics and outcomes among patients with chronic lymphocytic leukemia (CLL).

METHODS

The characteristics and outcomes of untreated African American (AA) patients with CLL (n = 84) were analyzed and compared with a reference nonblack (NB) patient population (n = 1571).

RESULTS

At the time of presentation, AA patients had lower median hemoglobin levels (12.9 g/dL vs 13.7 g/dL), higher β2 microglobulin levels (2.7 mg/dL vs 2.4 mg/dL), greater frequency of constitutional symptoms (27% vs 10%), unmutated immunoglobulin heavy-chain variable region (IGHV) mutation status (65% vs 47%), ζ-chain-associated protein kinase 70 (ZAP70) expression (58% vs 32%), and deletion of chromosome 17p or chromosome 11q (28% vs 17%; P ≤ 02 for each comparison). Fifty-one percent of AA patients and 39% of NB patients required first-line therapy and 91% and 88%, respectively, received chemoimmunotherapy. Overall response rates to treatment were 85% for AA patients and 94% for NB patients (P = .06); and the complete response rates were 56% and 58%, respectively (P = .87). The median survival of AA patients was shorter compared with that of NB patients (event-free survival: 36 months vs 61 months; P = .007; overall survival: 152 months vs not reached; P = .0001). AA race was an independent predictor of shorter event-free and overall survival in multivariable regression models.

CONCLUSIONS

The current results indicated that AA patients with CLL have more unfavorable prognostic characteristics and shorter survival compared with their NB counterparts.

Compliance with a protocol for acute lymphoblastic leukemia in childhood

Background

Remission rates achieved after the initial treatment of acute lymphoblastic leukemia may be similar in both developed and developing countries, but relapse rates are much higher in the latter. Thus, other reasons are needed, in addition to biological characteristics of the leukemic cells themselves, to explain the unfavorable evolution of patients living in unfavorable socioeconomic and cultural conditions.

Objective

The aim of this study was to retrospectively evaluate compliance to an acute lymphoblastic leukemia treatment protocol.

Methods

Main abstracted data were: total duration and reasons for interruption of chemotherapy, prescribed doses of 6-mercaptopurine, and median white blood cell and neutrophil counts during the maintenance phase. Interruptions of chemotherapy were considered inappropriate if they did not follow predetermined criteria established in the protocol.

Results

Fourteen of 73 patients (19.2%) unduly interrupted chemotherapy by determination of their physicians. The median white blood cell count was higher when compared with the protocol recommendations; the median 6-MP dose was lower than the standard recommended dose. The estimated probability of event-free survival was higher for patients with lower median leukocyte counts and close to those predetermined by the protocol. Event-free survival was also higher for children with a higher percentage of days without chemotherapy due to bone marrow or liver toxicity excluding undue interruptions. In multivariate analysis, both factors remained statistically significant. These results suggest that the intensity of maintenance chemotherapy may not have been enough in some children, to achieve adequate myelosuppression, hence the observation of higher leukocyte counts and none or rare episodes of therapy interruption.

Conclusions

Compliance to the therapeutic protocol by both doctors and patients should always be considered in the evaluation of therapeutic failure in acute lymphoblastic leukemia; strict adherence to treatment protocols contributes to better treatment results in acute lymphoblastic leukemia children.

Surrogate end points: how well do they represent patient-relevant end points?

This review takes a critical look at the concept of replacing patient-relevant end points, such as morbidity or mortality, with surrogate end points in clinical trials. Surrogate end points can be measured earlier in the course of a clinical trial and so are thought to accelerate the drug development process. Furthermore, they might be beneficial to the patients themselves by allowing faster adjustment of therapeutic strategies. However, the fact that in the past several promising surrogate end points have not fulfilled their expectations emphasizes the importance of applying strict evaluation criteria. The evaluation of the candidate surrogate end point prostate-specific antigen using the Prentice criteria and a meta-analytic approach is discussed. Prostate-specific antigen is often used to replace overall or progression-free survival in prostate cancer trials testing the benefit of medical interventions.

A curriculum for the new dental practitioner: preparing dentists for a prospective oral health care environment

The emerging concept of prospective health care would shift the focus of health care from disease management to disease prevention and health management. Dentistry has a unique opportunity to embrace this model of prospective and collaborative care and focus on the management of oral health. Academic dentistry must better prepare future dentists to succeed in this new health care environment by providing them with the scientific and technical knowledge required to understand and assess risk and practice disease prevention. Dental schools must consider creating career pathways for enabling future graduates to assume important leadership roles that will advance a prospective oral health care system.

Studying synthetic lethal interactions in the zebrafish system: insight into disease genes and mechanisms

The post-genomic era is marked by a pressing need to functionally characterize genes through understanding gene-gene interactions, as well as interactions between biological pathways. Exploiting a phenomenon known as synthetic lethality, in which simultaneous loss of two interacting genes leads to loss of viability, aids in the investigation of these interactions. Although synthetic lethal screening is a powerful technique that has been used with great success in many model organisms, including Saccharomyces cerevisiae, Drosophila melanogaster and Caenorhabditis elegans, this approach has not yet been applied in the zebrafish, Danio rerio. Recently, the zebrafish has emerged as a valuable system to model many human disease conditions; thus, the ability to conduct synthetic lethal screening using zebrafish should help to uncover many unknown disease-gene interactions. In this article, we discuss the concept of synthetic lethality and provide examples of its use in other model systems. We further discuss experimental approaches by which the concept of synthetic lethality can be applied to the zebrafish to understand the functions of specific genes.

Integrating pharmacogenetics into gemcitabine dosing--time for a change?

Increasing the efficacy of anticancer agents and avoiding toxic effects is a critical issue in clinical oncology. Identifying biomarkers that predict clinical outcome would ensure improved patient care. Gemcitabine is widely used to treat various solid tumors as a single agent or in combination with other drugs. The therapeutic index of gemcitabine is narrow, and abnormal pharmacokinetics leading to changes in plasma exposure is a major cause of adverse effects. A number of biomarkers have been proposed to predict efficacy of gemcitabine, focusing on molecular determinants of response identified at the tumor level. Genetic and functional deregulations that affect the disposition of a drug could be the reason for life-threatening adverse effects or treatment failure. In particular, deregulation of cytidine deaminase, the enzyme responsible for detoxification of most nucleotide analogs, should be examined. Identifying and validating biomarkers for pharmacogenetic testing before administration of gemcitabine is a step towards personalized medicine.

Personalized cancer therapy using a patient-derived tumor tissue xenograft model: a translational field worthy of exploring further?

It has long been observed that interpatient variability in response to anticancer drugs is associated with different outcomes. Oncologists continually hold the desire of matching the right therapeutic regimen with the right cancer patient, which is termed ‘personalized cancer therapy’. Rapid advances in genetics, genomics and related technologies are promising a new era of personalized cancer therapy based on individual molecular biomarkers. However, these molecular predictors of tumor response are far from perfect. Because of the inherent limitations in the current approaches for anticancer drugs response prediction, the need for new techniques to predict tumor response to therapy is urgent. Using a patient-derived human tumor tissue (PDTT) xenograft model to predict tumor response to therapy might be an ideal candidate method to choose. This article provides an overview of the achievements and limitations of genetic, genomic and proteomic molecular markers for personalized cancer therapy, and further discusses the potentials of using a PDTT xenograft model as a candidate strategy for personalized cancer therapy.

Vincristine: Can its therapeutic index be enhanced?

Vincristine is one of the most widely used and more effective drugs in paediatric oncology. The dose-limiting toxicity of neuropathy, lack of proven neuroprotective measures and an incomplete understanding of the pharmacokinetics and pharmacogenetics of vincristine have limited its therapeutic potential. Recent advances in the understanding of vincristine pharmacokinetics and pharmacogenetics, and potential methods of preventing neurotoxicity are reviewed which could enable dose escalation and dose individualisation in order to enhance the therapeutic index.

Systems biology in pharmacogenomic research: the way to personalized prescribing?

Response to pharmacotherapy can be highly variable amongst individuals. Pharmacogenomics may explain the interindividual variability in drug response due to genetic variation. However, besides genetics, many other factors can play a role in the response to pharmacotherapy, including disease severity, co-morbidity, environmental factors, therapy adherence and co-medication use. Better understanding of these factors and inter-relationships should bring about a much more effective approach to disease management. Systems biology that studies organisms as integrated and interacting networks of genes, proteins and biochemical reactions can contribute to this. Organisms are no longer studied part by part, but in a more integral manner. Integration of the genetic data with intermediate and end point phenotypic characterization may prove essential to define the inherent nature of drug effects. Therefore, in the future, a multidisciplinary systems-based approach will be necessary to deal with the bulk of the biological data that is available and, ultimately, to reach the goal of personalized prescribing.

Pharmacogenetics of the neurodevelopmental impact of anticancer chemotherapy

Pharmacogenetics holds the promise of minimizing adverse neurodevelopmental outcomes of cancer patients by identifying patients at risk, enabling the individualization of treatment and the planning of close follow-up and early remediation. This review focuses first on methotrexate, a drug often implicated in neurotoxicity, especially when used in combination with brain irradiation. The second focus is on glucocorticoids that have been found to be linked to adverse developmental effects in relation with the psychosocial environment. For both examples, we review how polymorphisms of genes encoding enzymes involved in specific mechanisms of action could moderate adverse neurodevelopmental consequences, eventually through common final pathways such as oxidative stress. We discuss a multiple hit model and possible strategies required to rise to the challenge of this integrative research.

Murine cardiac mtDNA: effects of transgenic manipulation of nucleoside phosphorylation

Mitochondrial toxicity results from pyrimidine nucleoside reverse transcriptase inhibitors (NRTIs) for HIV/AIDS. In the heart, this can deplete mitochondrial (mt) DNA and cause cardiac dysfunction (eg, left ventricle hypertrophy, LVH). Four unique transgenic, cardiac-targeted overexpressors (TGs) were generated to determine their individual impact on native mitochondrial biogenesis and effects of NRTI administration on development of mitochondrial toxicity. TGs included cardiac-specific overexpression of native thymidine kinase 2 (TK2), two pathogenic TK2 mutants (H121N and I212N), and a mutant of mtDNA polymerase, pol-gamma (Y955C). Each was treated with antiretrovirals (AZT-HAART, 3 or 10 weeks, zidovudine (AZT) + lamivudine (3TC) + indinavir, or vehicle control). Parameters included left ventricle (LV) performance (echocardiography), LV mtDNA abundance (real-time PCR), and mitochondrial fine structure (electron microscopy, EM) as a function of duration of treatment and presence of TG. mtDNA abundance significantly decreased in Y955C TG, increased in TK2 native and I212N TGs, and was unchanged in H121N TGs at 10 weeks regardless of treatment. Y955C and I212N TGs exhibited LVH during growth irrespective of treatment. Y955C TGs exhibited cardiomyopathy (CM) at 3 and 10 weeks irrespective of treatment, whereas H121N and I212N TGs exhibited CM only after 10 weeks AZT-HAART. EM features were consistent with cardiac dysfunction. mtDNA abundance and cardiac functional changes were related to TG expression of mitochondrially related genes, mutations thereof, and NRTIs.

Pharmacogenomic biomarker information in drug labels approved by the United States food and drug administration: prevalence of related drug use

STUDY OBJECTIVES

To review the labels of United States Food and Drug Administration (FDA)-approved drugs to identify those that contain pharmacogenomic biomarker information, and to collect prevalence information on the use of those drugs for which pharmacogenomic information is included in the drug labeling.

DESIGN

Retrospective analysis.

DATA SOURCES

The Physicians' Desk Reference Web site, Drugs@FDA Web site, and manufacturers' Web sites were used to identify drug labels containing pharmacogenomic information, and the prescription claims database of a large pharmacy benefits manager (insuring > 55 million individuals in the United States) was used to obtain drug utilization data.

MEASUREMENTS AND MAIN RESULTS

Pharmacogenomic biomarkers were defined, FDA-approved drug labels containing this information were identified, and utilization of these drugs was determined. Of 1200 drug labels reviewed for the years 1945-2005, 121 drug labels contained pharmacogenomic information based on a key word search and follow-up screening. Of those, 69 labels referred to human genomic biomarkers, and 52 referred to microbial genomic biomarkers. Of the labels referring to human biomarkers, 43 (62%) pertained to polymorphisms in cytochrome P450 (CYP) enzyme metabolism, with CYP2D6 being most common. Of 36.1 million patients whose prescriptions were processed by a large pharmacy benefits manager in 2006, about 8.8 million (24.3%) received one or more drugs with human genomic biomarker information in the drug label.

CONCLUSION

Nearly one fourth of all outpatients received one or more drugs that have pharmacogenomic information in the label for that drug. The incorporation and appropriate use of pharmacogenomic information in drug labels should be tested for its ability to improve drug use and safety in the United States.

A generalizable strategy for imaging pre-mRNA levels in living subjects using spliceosome-mediated RNA trans-splicing

Molecular imaging of gene expression is currently hindered by the lack of a generalizable platform for probe design. For any gene of interest, a probe that targets protein levels must often be generated empirically. Targeting gene expression at the level of mRNA, however, would allow probes to be built on the basis of sequence information alone. Presented here is a class of generalizable probes that can image pre-mRNA in a sequence-specific manner, using signal amplification and a facile method of delivery.

METHODS

Pre-trans-splicing molecules (PTMs) were engineered to capitalize on the phenomenon of spliceosome-mediated RNA trans-splicing. Using a modular binding domain that confers specificity by base-pair complementarity to the target pre-mRNA, PTMs were designed to target a chimeric target mini gene and trans-splice the Renilla luciferase gene onto the end of the target. PTMs and target genes were transfected in cell culture and assessed by luciferase assay, reverse-transcriptase polymerase chain reaction, Western blot, and rapid analysis of 5' cDNA ends. PTMs and target genes were also assessed in vivo by hydrodynamic delivery in mice.

RESULTS

Efficiency and specificity of the trans-splicing reaction were found to vary depending on the binding domain length and structure. Specific trans-splicing was observed in living animals (P = 0.0862, Kruskal-Wallis test).

CONCLUSION

Described here is a model system used to demonstrate the feasibility of spliceosome-mediated RNA trans-splicing for imaging gene expression at the level of pre-mRNA using optical imaging techniques in living animals. The experiments reported here show proof of principle for a generalizable imaging probe against RNA that can amplify signal on detection and be delivered using existing gene delivery methodology.

A SAS-based solution to evaluate study design efficiency of phase I pediatric oncology trials via discrete event simulation

Previous exploration of oncology study design efficiency has focused on Markov processes alone (probability-based events) without consideration for time dependencies. Barriers to study completion include time delays associated with patient accrual, inevaluability (IE), time to dose limiting toxicities (DLT) and administrative and review time. Discrete event simulation (DES) can incorporate probability-based assignment of DLT and IE frequency, correlated with cohort in the case of DLT, with time-based events defined by stochastic relationships. A SAS-based solution to examine study efficiency metrics and evaluate design modifications that would improve study efficiency is presented. Virtual patients are simulated with attributes defined from prior distributions of relevant patient characteristics. Study population datasets are read into SAS macros which select patients and enroll them into a study based on the specific design criteria if the study is open to enrollment. Waiting times, arrival times and time to study events are also sampled from prior distributions; post-processing of study simulations is provided within the decision macros and compared across designs in a separate post-processing algorithm. This solution is examined via comparison of the standard 3+3 decision rule relative to the "rolling 6" design, a newly proposed enrollment strategy for the phase I pediatric oncology setting.

Pharmacogenetics of heart failure: evidence, opportunities, and challenges for cardiovascular pharmacogenomics

Heart failure is a significant medical problem affecting more than five million people in the USA alone. Although clinical trials of pharmacological agents have demonstrated significant reductions in the relative risk of mortality across populations, absolute mortality remains high. In addition, individual variation in response is great. Some of this variation may be explained by genetic polymorphism. In this paper, we review the key studies to date in heart failure pharmacogenetics, setting this against a background of recent progress in the genetics of warfarin metabolism. Several polymorphisms that have supporting molecular and clinical data in the heart failure literature are reviewed, among them the beta1-adrenergic receptor variant Arg389Gly and the angiotensin converting enzyme gene insertion/deletion polymorphism. These variants and others are responsible for a fraction of the total variation seen in the treatment response to heart failure. With the dawn of the genomic age, further pharmacogenetic and new pharmacogenomic studies will advance our ability to tailor the treatment of heart failure.