The cost-effectiveness of HLA-B*5701 genetic screening to guide initial antiretroviral therapy for HIV

Cost Effectiveness of Pharmacogenetic Testing for Drugs with Clinical Pharmacogenetics Implementation Consortium (CPIC) Guidelines: A Systematic Review

The objective of this study was to evaluate the evidence on cost-effectiveness of pharmacogenetic (PGx)-guided treatment for drugs with Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines. A systematic review was conducted using multiple biomedical literature databases from inception to June 2021. Full articles comparing PGx-guided with nonguided treatment were included for data extraction. Quality of Health Economic Studies (QHES) was used to assess robustness of each study (0-100). Data are reported using descriptive statistics. Of 108 studies evaluating 39 drugs, 77 (71%) showed PGx testing was cost-effective (CE) (N = 48) or cost-saving (CS) (N = 29); 21 (20%) were not CE; 10 (9%) were uncertain. Clopidogrel had the most articles (N = 23), of which 22 demonstrated CE or CS, followed by warfarin (N = 16), of which 7 demonstrated CE or CS. Of 26 studies evaluating human leukocyte antigen (HLA) testing for abacavir (N = 8), allopurinol (N = 10), or carbamazepine/phenytoin (N = 8), 15 demonstrated CE or CS. Nine of 11 antidepressant articles demonstrated CE or CS. The median QHES score reflected high-quality studies (91; range 48-100). Most studies evaluating cost-effectiveness favored PGx testing. Limited data exist on cost-effectiveness of preemptive and multigene testing across disease states.

HLA pharmacogenetic markers of drug hypersensitivity from the perspective of the populations of the Greater Middle East

Specific HLA associations with drug hypersensitivity may vary between geographic regions and ethnic groups. There are little to no data related to HLA-drug hypersensitivity on populations who reside in the Greater Middle East (GME), a vast region spanning from Morocco in the west to Pakistan in the east. In this review, the authors intended to summarize the significant HLA alleles associated with hypersensitive drug reactions induced by different drugs, as have been found in different populations, and to summarize the prevalence of these alleles in the specific and diverse populations of the GME. For example, HLA-B*57:01 allele prevalence, associated with abacavir-induced hypersensitivity, ranges from 1% to 3%, and HLA-DPB1*03:01 prevalence, associated with aspirin-induced asthma, ranges from 10% to 14% in the GME population. Studying pharmacogenomic associations in the ethnic groups of the GME may allow the discovery of new associations, confirm ones found with a low evidence rate and enable cost-effectiveness analysis of allele screening before drug use.

Pharmacogenetic testing for adverse drug reaction prevention: systematic review of economic evaluations and the appraisal of quality matters for clinical practice and implementation

Background

Genetic testing has potential roles in identifying whether an individual would have risk of adverse drug reactions (ADRs) from a particular medicine. Robust cost-effectiveness results on genetic testing would be useful for clinical practice and policy decision-making on allocating resources effectively. This study aimed to update a systematic review on economic evaluations of pharmacogenetic testing to prevent ADRs and critically appraise the quality of reporting and sources of evidence for model input parameters.

Methods

We searched studies through Medline via PubMed, Scopus and CRD’s NHS Economic Evaluation up to October 2019. Studies investigating polymorphism-based pharmacogenetic testing, which guided drug therapies to prevent ADRs, using economic evaluation methods were included. Two reviewers independently performed data extraction and assessed the quality of reporting using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) guidelines and the quality of data sources using the hierarchy of evidence developed by Cooper et al.

Results

Fifty-nine economic evaluations of pharmacogenetic testing to avoid drug-induced ADRs were found between 2002 and 2018. Cost-utility and cost-effectiveness analyses were the most common methods of economic evaluation of pharmacogenetic testing. Most studies complied with the CHEERS checklist, except for single study-based economic evaluations which did not report uncertainty analysis (78%). There was a lack of high-quality evidence not only for estimating the clinical effectiveness of pharmacogenetic testing, but also baseline clinical data. About 14% of the studies obtained clinical effectiveness data of testing from a meta-analysis of case-control studies with direct comparison, which was not listed in the hierarchy of evidence used.

Conclusions

Our review suggested that future single study-based economic evaluations of pharmacogenetic testing should report uncertainty analysis, as this could significantly affect the robustness of economic evaluation results. A specific ranking system for the quality of evidence is needed for the economic evaluation of pharmacogenetic testing of ADRs. Differences in parameters, methods and outcomes across studies, as well as population-level and system-level differences, may lead to the difficulty of comparing cost-effectiveness results across countries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-021-07025-8.

Prevalence of human leukocyte antigen HLA-B*57:01 in individuals with HIV in West and Central Africa

BACKGROUND

The presence of the human leukocyte antigen HLA-B*57:01 is associated with the development of a hypersensitivity reaction to abacavir (ABC). Limited data exist on HLA-B*57:01 prevalence in individuals with HIV-1 in Africa. This study aimed to estimate HLA-B*57:01 prevalence in individuals with HIV-1 in West and Central Africa.

METHODS

A cross-sectional study was conducted in four countries in West and central Africa (Burkina-Faso, Côte d'Ivoire, Gabon, and Togo) from January 2016 to February 2020 to determine the status of HLA-B*57:01 in adults with HIV-1. The presence of HLA-B*57:01 was determined by using Single Specific Primer-Polymerase Chain Reaction (SSP-PCR) in blood samples. Prevalence rates were stratified based on country.

RESULTS

A total of 4016 (69.8% women) individuals with HIV were enrolled. Their median age was 45, and the interquartile range was 38-52. We included 500 (12.4%) patients in Burkina-Faso, 1453 (36.2%) in Côte d'Ivoire, 951 (23.7%) in Gabon, and 1112 (27.7%) in Togo. The overall HLA-B*57:01 prevalence was 0.1% [95% CI: 0.0-0.2%]. The prevalence of HLA-B*57:01 was similar according to the four countries. Only one case was reported in each country except Togo, with no cases.

CONCLUSIONS

HLA-B*57:01 prevalence is low in individuals with HIV in West and central Africa, and there is no difference among countries. This study does not confirm the utility of HLA-B*57:01 allele testing for abacavir use in this region.

In-Vitro Approaches to Predict and Study T-Cell Mediated Hypersensitivity to Drugs

Mitigating the risk of drug hypersensitivity reactions is an important facet of a given pharmaceutical, with poor performance in this area of safety often leading to warnings, restrictions and withdrawals. In the last 50 years, efforts to diagnose, manage, and circumvent these obscure, iatrogenic diseases have resulted in the development of assays at all stages of a drugs lifespan. Indeed, this begins with intelligent lead compound selection/design to minimize the existence of deleterious chemical reactivity through exclusion of ominous structural moieties. Preclinical studies then investigate how compounds interact with biological systems, with emphasis placed on modeling immunological/toxicological liabilities. During clinical use, competent and accurate diagnoses are sought to effectively manage patients with such ailments, and pharmacovigilance datasets can be used for stratification of patient populations in order to optimise safety profiles. Herein, an overview of some of the in-vitro approaches to predict intrinsic immunogenicity of drugs and diagnose culprit drugs in allergic patients after exposure is detailed, with current perspectives and opportunities provided.

Pharmacogenetic Testing: A Tool for Personalized Drug Therapy Optimization

Pharmacogenomics is a study of how the genome background is associated with drug resistance and how therapy strategy can be modified for a certain person to achieve benefit. The pharmacogenomics (PGx) testing becomes of great opportunity for physicians to make the proper decision regarding each non-trivial patient that does not respond to therapy. Although pharmacogenomics has become of growing interest to the healthcare market during the past five to ten years the exact mechanisms linking the genetic polymorphisms and observable responses to drug therapy are not always clear. Therefore, the success of PGx testing depends on the physician's ability to understand the obtained results in a standardized way for each particular patient. The review aims to lead the reader through the general conception of PGx and related issues of PGx testing efficiency, personal data security, and health safety at a current clinical level.

Global Frequencies of Clinically Important HLA Alleles and Their Implications For the Cost-Effectiveness of Preemptive Pharmacogenetic Testing

Immune-mediated drug hypersensitivity reactions are an important source of iatrogenic morbidity and mortality. Human leukocyte antigen (HLA)-B*57:01, HLA-B*15:02, HLA-A*31:01, and HLA-B*58:01 constitute established risk factors and preemptive genotyping of these HLA alleles in patients prior to the initiation of abacavir, carbamazepine, and allopurinol-based therapies can prevent toxicity and improve patient outcomes. However, the cost-effectiveness of preemptive HLA testing has only been evaluated in the United States and few countries in Europe and Asia. In this study, we consolidated HLA genotypes from 3.5-6.4 million individuals across up to 74 countries and modeled the country-specific cost-effectiveness of genetic testing. We find major ethnogeographic differences in risk allele prevalence, which translated into pronounced differences in the number of patients needed to test to prevent one case of severe hypersensitivity reactions between countries and populations. At incremental cost-effectiveness ratio thresholds of $40,000, testing of HLA-B*57:01 in patients initiating abacavir was cost-effective in the majority of countries with potential exceptions of East Asia, Saudi Arabia, Ghana, and Zimbabwe. For carbamazepine, preemptive genotyping of HLA-B*15:02 is only cost-effective across most of East and South Asia, whereas HLA-A*31:01 testing is likely to be cost-effective globally. Testing of HLA-B*58:01 is more likely to be cost-effective throughout Africa and Asia compared with Europe and the Americas. We anticipate that this data set can serve as an important resource for clinicians and health economists to guide clinical decision making and inform public healthcare strategies.

Drug-Induced liver Injury Associated with Severe Cutaneous Hypersensitivity Reactions: A Complex Entity in Need of a Multidisciplinary Approach

Idiosyncratic drug-induced liver injury (DILI) occasionally occurs in the setting of severe cutaneous adverse reactions (SCARs), including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN) and drug reaction with eosinophilia and systemic symptoms (DRESS). This strengthens the proposed immunologic mechanism associated with this adverse reaction. DRESS exhibits the most common association with DILI. SCARs have a wide spectrum of heterogeneous clinical presentations and severity, and genetic predisposition has been identified. In the context of SCARs, DILI present a different clinical picture, ranging from mild injury to acute liver failure. Elucidating the role of DILI in the clinical presentation and outcome of SCARs represents a challenge due to limited information from published studies and the lack of consensus on definitions. The cholestatic and mixed pattern of liver damage typically predominates in the case of DILI associated with SCARs, which is different from DILI without SCARs where hepatocellular is the most common injury pattern. Only a few drugs have been associated with both DILI and SCARs. Is this article, the criteria used for DILI recognition among SCARS have been revised and discussed, along with the drugs most commonly involved in these syndromes as well as the outcome, prognostic factors and the need for a multidisciplinary approach to improve the management of DILI in the context of SCARs.

Modification of the cyclopropyl moiety of abacavir provides insight into the structure activity relationship between HLA-B*57:01 binding and T-cell activation

BACKGROUND

Abacavir is associated with hypersensitivity reactions in individuals positive for the HLA-B*57:01 allele. The drug binds within the peptide binding groove of HLA-B*57:01 altering peptides displayed on the cell surface. Presentation of these HLA-abacavir-peptide complexes to T-cells is hypothesized to trigger a CD8⁺ T-cell response underpinning the hypersensitivity. Thus, the aim of this study was to explore the relationship between the structure of abacavir with HLA-B*57:01 binding and the CD8⁺ T-cell activation.

METHODS

Seventeen abacavir analogues were synthesized and cytokine secretion from abacavir/abacavir analogue-responsive CD8⁺ T-cell clones was measured using IFN-γ ELIspot. In silico docking studies were undertaken to assess the predicted binding poses of the abacavir analogues within the HLA-B*57:01 peptide binding groove. In parallel, the effect of selected abacavir analogues on the repertoire of self-peptides presented by cellular HLA-B*57:01 was characterized using mass spectrometry.

RESULTS

Abacavir and ten analogues stimulated CD8⁺ T-cell IFN-γ release. Molecular docking of analogues that retained antiviral activity demonstrated a relationship between predicted HLA-B*57:01 binding orientations and the ability to induce a T-cell response. Analogues that stimulated T-cells displayed a perturbation of the natural peptides displayed by HLA-B*57:01. The antigen-specific CD8⁺ T-cell response was dependent on the enantiomeric form of abacavir at both cyclopropyl and cyclopentyl regions.

CONCLUSION

Alteration of the chemical constitution of abacavir generates analogues that retain a degree of pharmacological activity, but have variable ability to activate T-cells. Modelling and immunopeptidome analysis delineate how drug HLA-B*57:01 binding and peptide display by antigen presenting cells relate to the activation of CD8⁺ T-cells.

T-Cell Activation by Low Molecular Weight Drugs and Factors That Influence Susceptibility to Drug Hypersensitivity

Drug hypersensitivity reactions adversely affect treatment outcome, increase the length of patients' hospitalization, and limit the prescription options available to physicians. In addition, late stage drug attrition and the withdrawal of licensed drugs cost the pharmaceutical industry billions of dollars. This significantly increases the overall cost of drug development and by extension the price of licensed drugs. Drug hypersensitivity reactions are characterized by a delayed onset, and reactions tend to be more serious upon re-exposure. The role of drug-specific T-cells in the pathogenesis of drug hypersensitivity reactions and definition of the nature of the binding interaction of drugs with HLA and T-cell receptors continues to be the focus of intensive research, primarily because susceptibility is associated with expression of one or a small number of HLA alleles. This review critically examines the mechanisms of T-cell activation by drugs. Specific examples of drugs that activate T-cells via the hapten, the pharmacological interaction with immune receptors and the altered self-peptide repertoire pathways, are discussed. Furthermore, the impacts of drug metabolism, drug-protein adduct formation, and immune regulation on the development of drug antigen-responsive T-cells are highlighted. The knowledge gained from understanding the pathways of T-cell activation and susceptibility factors for drug hypersensitivity will provide the building blocks for the development of predictive in vitro assays that will prevent or help to minimize the incidence of these reactions in clinic.

Economic evaluation studies in the field of HIV/AIDS: bibliometric analysis on research development and scopes (GAPRESEARCH)

Background

The rapid decrease in international funding for HIV/AIDS has been challenging for many nations to effectively mobilize and allocate their limited resources for HIV/AIDS programs. Economic evaluations can help inform decisions and strategic planning. This study aims to examine the trends and patterns in economic evaluation studies in the field of HIV/AIDS and determine their research landscapes.

Methods

Using the Web of Science databases, we synthesized the number of papers and citations on HIV/AIDS and economic evaluation from 1990 to 2017. Collaborations between authors and countries, networks of keywords and research topics were visualized using frequency of co-occurrence and Jaccards’ similarity index. A Latent Dirichlet Allocation (LDA) analysis to categorize papers into different topics/themes.

Results

A total of 372 economic evaluation papers were selected, including 351 cost-effectiveness analyses (CEA), 11 cost-utility analyses (CUA), 12 cost-benefit analyses (CBA). The growth of publications, their citations and usages have increased remarkably over the years. Major research topics in economic evaluation studies consisted of antiretroviral therapy (ART) initiation and treatment; drug use prevention interventions and prevention of mother-to-child transmission interventions. Moreover, lack of contextualized evidence was found in specific settings with high burden HIV epidemics, as well as emerging most-at-risk populations such as trans-genders or migrants.

Conclusion

This study highlights the knowledge and geographical discrepancies in HIV/AIDS economic evaluation literature. Future research directions are also informed for advancing economic evaluation in HIV/AIDS research.

Pharmacogenomics

Genomic medicine, which uses DNA variation to individualise and improve human health, is the subject of this Series of papers. The idea that genetic variation can be used to individualise drug therapy-the topic addressed here-is often viewed as within reach for genomic medicine. We have reviewed general mechanisms underlying variability in drug action, the role of genetic variation in mediating beneficial and adverse effects through variable drug concentrations (pharmacokinetics) and drug actions (pharmacodynamics), available data from clinical trials, and ongoing efforts to implement pharmacogenetics in clinical practice.

Pharmacogenomics in dermatology: tools for understanding gene-drug associations

Pharmacogenomics aims to associate human genetic variability with differences in drug phenotypes in order to tailor drug treatment to individual patients. The massive amount of genetic data generated from large cohorts of patients with variable drug phenotypes have led to advances in this field. Understanding the application of pharmacogenomics in dermatology could inform clinical practice and provide insight for future research. The Pharmacogenomics Knowledge Base and the Clinical Pharmacogenetics Implementation Consortium are among the resources to help clinicians and researchers navigate the many gene-drug associations that have already been discovered. The implementation of clinical pharmacogenomics within health care systems remains an area of ongoing development. This review provides an introduction to the field of pharmacogenomics and to current pharmacogenomics resources using examples of gene-drug associations relevant to the field of dermatology.

Health Care Costs in a Cohort of HIV-Infected U.S. Veterans Receiving Regimens Containing Tenofovir Disoproxil Fumarate/Emtricitabine

BACKGROUND

Tenofovir disoproxil fumarate (TDF), a key component in many human immunodeficiency virus (HIV) treatment regimens, is associated with increased renal and bone toxicities. The contributions of such toxicities to treatment costs, as well as the relative differences in treatment costs for various TDF/emtricitabine (FTC) regimens, remains unexplored.

OBJECTIVE

To estimate and compare mean overall and renal- and bone-specific costs, including total, inpatient, outpatient, and pharmacy costs in patients treated with TDF/FTC+efavirenz (EFV) compared with several non-EFV-containing TDF/FTC regimens.

METHODS

We conducted a national cohort study of treatment-naive HIV-infected U.S. veterans who initiated treatment from 2003 to 2015 with TDF/FTC in combination with EFV, elvitegravir/cobicistat, rilpivirine, or ritonavir-boosted protease inhibitors (atazanavir, darunavir, or lopinavir). Outcomes of interest were quarterly total, inpatient, outpatient, and pharmacy costs using data from the Veterans Health Administration (VHA) electronic medical record and Managerial Cost Accounting System (an activity-based accounting system that allocates VHA expenditures to patient encounters). We controlled for measured confounders using inverse probability of treatment (IPT) weights and assessed differences using standardized mean differences (SMDs). For comparisons where SMDs exceeded 0.1 after IPT weighting, we used the more conservative matching weights in sensitivity analyses. For hypothesis testing, we compared IPT-adjusted differences in quarterly costs between treatment groups using Mann-Whitney U-tests and generalized estimating equation (GEE) regression models.

RESULTS

Of 33,048 HIV-positive veterans, 7,222 met eligibility criteria, including 4,172 TDF/FTC + EFV recipients; mean (SD) age of the cohort was 50.0 (10.0) years; 96.7% were male; 60.1% were black; and 30.1% were white. Quarterly periods of exposure to EFV-containing regimens were 22,499 and of exposure to non-EFV-containing regimens were 11,633. After IPT weighting, absolute SMDs were < 0.1 except for a few covariates in the rilpivirine comparison. The per-patient adjusted mean total quarterly costs were $7,145 for EFV versus $8,726 for non-EFV (P < 0.001; Mann-Whitney U-test) and the per-patient adjusted mean difference in total quarterly costs was $1,419 lower for EFV versus all non-EFV combined (P < 0.001; GEE model). Corresponding values for outpatient costs ($2,656 vs. $2,942; P < 0.001; difference, -$254; P = 0.001), inpatient costs ($2,009 vs. $2,614; P < 0.001), radiology costs ($213 vs. $276; P < 0.001), and pharmacy costs ($2,480 vs. $3,170; P < 0.001; difference, -$600; P < 0.001) were all lower for EFV versus all non-EFV combined. Findings based on matching weights were qualitatively similar. Contributions of renal and bone costs to the total costs of treatment were very small, ranging between $52 and $94 per patient per quarter for renal outcomes and between $6 and $114 for bone outcomes.

CONCLUSIONS

Among 7,222 HIV-treated veterans over an average follow-up of 1.2 years per patient, those patients receiving TDF/FTC + EFV had lower overall health care costs compared with those receiving non-EFV regimens.

DISCLOSURES

This study was funded by Bristol-Myers Squibb. Nelson, Ma, Crook, Knippenberg, Nyman, and LaFleur are employees of the University of Utah, which received a grant from Bristol-Myers Squibb to conduct this study. Nyman also discloses honoraria for consulting from Otsuka and for writing a book chapter from Fresenius. La Fleur reports advisory board and consulting fees from Bristol-Myers Squibb outside of this study. Paul and Esker are employees of, and own stock in, Bristol-Myers Squibb.

Genetic Testing in Clinical Settings

Genetic testing is used for screening, diagnosis, and prognosis of diseases consistent with a genetic cause and to guide drug therapy to improve drug efficacy and avoid adverse effects (pharmacogenomics). This In Practice review aims to inform about DNA-related genetic test availability, interpretation, and recommended clinical actions based on results using evidence from clinical guidelines, when available. We discuss challenges that limit the widespread use of genetic information in the clinical care setting, including a small number of actionable genetic variants with strong evidence of clinical validity and utility, and the need for improving the health literacy of health care providers and the public, including for direct-to-consumer tests. Ethical, legal, and social issues and incidental findings also need to be addressed. Because our understanding of genetic factors associated with disease and drug response is rapidly increasing and new genetic tests are being developed that could be adopted by clinicians in the short term, we also provide extensive resources for information and education on genetic testing.

Clinical pharmacogenomics testing in the era of next generation sequencing: challenges and opportunities for precision medicine

INTRODUCTION

The rapid development and dramatic decrease in cost of sequencing techniques have ushered the implementation of genomic testing in patient care. Next generation DNA sequencing (NGS) techniques have been used increasingly in clinical laboratories to scan the whole or part of the human genome in order to facilitate diagnosis and/or prognostics of genetic disease. Despite many hurdles and debates, pharmacogenomics (PGx) is believed to be an area of genomic medicine where precision medicine could have immediate impact in the near future. Areas covered: This review focuses on lessons learned through early attempts of clinically implementing PGx testing; the challenges and opportunities that PGx testing brings to precision medicine in the era of NGS. Expert commentary: Replacing targeted analysis approach with NGS for PGx testing is neither technically feasible nor necessary currently due to several technical limitations and uncertainty involved in interpreting variants of uncertain significance for PGx variants. However, reporting PGx variants out of clinical whole exome or whole genome sequencing (WES/WGS) might represent additional benefits for patients who are tested by WES/WGS.

Frank Stinchfield Award: Identification of the At-risk Genotype for Development of Pseudotumors Around Metal-on-metal THAs

BACKGROUND

Once touted as the future of hip arthroplasty, metal-on-metal (MoM) bearing surfaces have fallen sharply from favor with the emergence of a strong body of evidence demonstrating unacceptably high premature implant failure rates. The previously unpredictable development of adverse local tissue reactions (ALTRs) has been a substantive contributor to this. Although the underlying pathophysiology of these so-called "pseudotumors" is now well understood, the fundamental predisposing patient risk factors have remained elusive.

QUESTIONS/PURPOSES

The aim of this research, as a clinical-genotype correlation analysis, was to identify specific alleles (genes) associated with the development of ALTRs in patients with in situ MoM THAs.

METHODS

A case-control study of patients who received a large-head, primary MoM THA between 2005 and 2008 was performed with a minimum followup of 5 years. Twenty-six patients who had undergone revision of a primary MoM THA secondary to symptomatic ALTRs were recruited. The mean timeframe from primary MoM THA to symptomatic revision was 5.5 years (range, 1-10 years). Twenty-eight control subjects were randomly selected asymptomatic patients with no evidence of ALTRs on protocol-specific screening. Baseline demographics and high-resolution genotype (human leukocyte antigen [HLA] Class II) were collected for all patients. Cohorts were similar with respect to age at the time of primary MoM THA (mean, 54.8 versus 54.9 years, p = 0.95) and serum cobalt (mean, 5.5 versus 8.5 μg/L, p = 0.09) and chromium concentrations (mean, 2.9 versus 4.2 μg/L, p = 0.27). The association between genotype and revision surgery secondary to ALTRs was determined with gender as a covariate.

RESULTS

The prevalence of the risk genotype was 30% (16 of 54) among the entire cohort. Adjusting for sex, the odds of revision were 6.1 times greater among patients with the risk genotype present than among patients without (95% confidence interval [CI], 1.5-25.4; p = 0.01). Among females, the specificity of the risk genotype was 1.0 (95% CIexact, 0.5-1.0; pexact = 0.03), and for males, it was 0.8 (95% CIexact, 0.6-0.9; pexact < 0.01).

CONCLUSIONS

The findings of this study suggest that, among patients with a primary MoM THA, allelic variation within the HLA Class II loci may be a strong, independent risk factor associated with the need for subsequent revision surgery secondary to pseudotumor formation.

CLINICAL RELEVANCE

Given the hypothesis-generating nature of this novel undertaking, confirmatory prospective clinical studies are required to further elucidate this correlation and to explore the clinical utility of targeted genetic screening in this specific population. This research may, however, represent a key missing piece in the puzzle that is metal ion-induced pseudotumor formation.

Rare disease prevention and treatment: the need for a level playing field

Pharmacogenetic tests are being used increasingly to prevent rare and potentially life-threatening adverse drug reactions. For many tests, however, cost-effectiveness is hard to demonstrate, and with the exception of a few cases, widespread implementation remains a distant prospect. Many orphan drugs for rare diseases are also not cost effective but are nonetheless normally reimbursed. In this article, we argue that the health technology assessment of pharmacogenetic tests aimed to prevent rare but severe adverse drug reactions should be on a level playing field with orphan drugs. This is supported by a number of arguments, concerning the severity, rarity and iatrogenic nature of adverse drug reactions, the distribution of benefits and costs and societal preference towards prevention over treatment.

Implementation of Pharmacogenomics in Everyday Clinical Settings

Currently, germline pharmacogenomics (PGx) is successfully implemented within certain specialties in clinical care. With the integration of PGx in pharmacotherapy multiple stakeholders are involved, which are identified in this chapter. Clinically relevant pharmacogenes with their related PGx test are discussed, along with diagnostic test criteria to guide clinicians and policy makers in PGx test selection. The chapter further reviews the similarities and the differences between the guidelines of the Dutch Pharmacogenetics Working Group and the Clinical Pharmacogenetics Implementation Consortium which both support healthcare professionals in understanding PGx test results and help guiding pharmacotherapy by providing evidence-based dosing recommendations. Finally, clinical studies which provide scientific evidence and information on cost-effectiveness supporting clinical implementation of PGx in clinical care are discussed along with the remaining barriers for adoption of PGx testing by healthcare professionals.

The Cost of Penicillin Allergy Evaluation

BACKGROUND

Unverified penicillin allergy leads to adverse downstream clinical and economic sequelae. Penicillin allergy evaluation can be used to identify true, IgE-mediated allergy.

OBJECTIVE

To estimate the cost of penicillin allergy evaluation using time-driven activity-based costing (TDABC).

METHODS

We implemented TDABC throughout the care pathway for 30 outpatients presenting for penicillin allergy evaluation. The base-case evaluation included penicillin skin testing and a 1-step amoxicillin drug challenge, performed by an allergist. We varied assumptions about the provider type, clinical setting, procedure type, and personnel timing.

RESULTS

The base-case penicillin allergy evaluation costs $220 in 2016 US dollars: $98 for personnel, $119 for consumables, and $3 for space. In sensitivity analyses, lower cost estimates were achieved when only a drug challenge was performed (ie, no skin test, $84) and a nurse practitioner provider was used ($170). Adjusting for the probability of anaphylaxis did not result in a changed estimate ($220); although other analyses led to modest changes in the TDABC estimate ($214-$246), higher estimates were identified with changing to a low-demand practice setting ($268), a 50% increase in personnel times ($269), and including clinician documentation time ($288). In a least/most costly scenario analyses, the lowest TDABC estimate was $40 and the highest was $537.

CONCLUSIONS

Using TDABC, penicillin allergy evaluation costs $220; even with varied assumptions adjusting for operational challenges, clinical setting, and expanded testing, penicillin allergy evaluation still costs only about $540. This modest investment may be offset for patients treated with costly alternative antibiotics that also may result in adverse consequences.

Genetic Factors Influencing Drug-Induced Liver Injury: Do They Have a Role in Prevention and Diagnosis?

Purpose of Review

The pathogenesis of DILI is currently unknown; however, research has shown strong genetic associations with some DILIs. This paper describes the variant alleles uncovered by GWAS and discusses their potential role as susceptibility biomarkers.

Recent Findings

An association with HLADRB1*15:01 and amoxicillin/clavulanate DILI has been shown by a number of research groups. The presence of the HLA-B*57:01 allele has been associated with an 81-fold increased risk of flucloxacillin DILI. The HLA-B*35:02 allele has significant association with minocycline DILI.

Summary

With the exception of abacavir for HIV therapy, no other prospective genetic screening tests have met the threshold for clinical application. This is largely because DILI incidence is too low to warrant the cost and effort associated with testing. Perhaps, with the development of personalised medicine, a panel of genes for disease susceptibility, drug efficacy and adverse reactions could be tested once off. This would change the cost-effectiveness paradigm, personalise healthcare and reduce DILI risk by avoiding medications in patients with specific HLA alleles.

Cost-effectiveness of pharmacogenetic-guided treatment: are we there yet?

Pharmacogenetics (PGx) has the potential to personalize pharmaceutical treatments. Many relevant gene-drug associations have been discovered, but PGx-guided treatment needs to be cost-effective as well as clinically beneficial to be incorporated into standard health-care. We reviewed economic evaluations for PGx associations listed in the US Food and Drug Administration (FDA) Table of Pharmacogenomic Biomarkers in Drug Labeling. We determined the proportion of evaluations that found PGx-guided treatment to be cost-effective or dominant over the alternative strategies, and estimated the impact on this proportion of removing the cost of genetic testing. Of the 137 PGx associations in the FDA table, 44 economic evaluations, relating to 10 drugs, were identified. Of these evaluations, 57% drew conclusions in favour of PGx testing, of which 30% were cost-effective and 27% were dominant (cost-saving). If genetic information was freely available, 75% of economic evaluations would support PGx-guided treatment, of which 25% would be cost-effective and 50% would be dominant. Thus, PGx-guided treatment can be a cost-effective and even a cost-saving strategy. Having genetic information readily available in the clinical health record is a realistic future prospect, and would make more genetic tests economically worthwhile.

HLA-B*57: 01 genotyping in the prevention of hypersensitivity to abacavir: 5 years of experience

INTRODUCTION

Most of the cost-effectiveness analyses are based on estimations to make decisions on the future implementation of a test. However, the model should be verified with real data to prove that previous estimations have been successfully fulfilled.

OBJECTIVE

To study the economic impact of the systematic HLA-B*57:01 genotyping in preventing hypersensitivity reactions (HSRs) in the patient population of a tertiary-care hospital treated with abacavir (ABC) using retrospective data of 5 years of experience.

METHODS

A retrospective study was carried out with two cohorts including 780 and 473 patients before and after the implementation of the systematic HLA-B*57:01 genotyping before ABC treatment. Cost-effectiveness analysis was carried out by the parameter 'cost per HSR avoided'. The clinical utility of the test was verified by evaluating the differences in HSR incidence between both cohorts. Finally, a sensitivity analysis including all variables was carried out.

RESULTS

In the population studied, systematic genotyping represents an additional cost of &OV0556;306 per HSR avoided. In the sensitivity analysis, pharmacological therapy cost is the major influencing factor found in the estimation of the 'cost per HSR avoided'. In terms of clinical utility, the incidence ratio was 0.040 (95% confidence interval 0.0009-0.2399) and statistically significant differences were found between both groups (P=1.40×10).

CONCLUSION

Retrospective data from 5 years of experience have confirmed the cost-effectiveness of the systematic genotyping in candidate patients for ABC therapy, and have shown that cost-effectiveness is a dynamic parameter closely linked to allele prevalence and pharmacological therapy costs.

Pharmacogenetic considerations in the treatment of HIV

After the introduction of highly active antiretroviral therapy in the 1990s, the perception of the diagnosis of HIV infection gradually shifted from a 'death sentence' to a chronic disease requiring long-term treatment. The host genetic variability has been shown to play a relevant role in both antiretroviral drugs bioavailability and adverse effects susceptibility. Knowledge about pharmacogenetics role in HIV infection treatment has largely increased over the last years, and is reviewed in the present report, as well as future perspectives for the inclusion of pharmacogenetics information in the directing of HIV infection treatment.

The Importance of Patient-Specific Factors for Hepatic Drug Response and Toxicity

Responses to drugs and pharmacological treatments differ considerably between individuals. Importantly, only 50%-75% of patients have been shown to react adequately to pharmacological interventions, whereas the others experience either a lack of efficacy or suffer from adverse events. The liver is of central importance in the metabolism of most drugs. Because of this exposed status, hepatotoxicity is amongst the most common adverse drug reactions and hepatic liabilities are the most prevalent reason for the termination of development programs of novel drug candidates. In recent years, more and more factors were unveiled that shape hepatic drug responses and thus underlie the observed inter-individual variability. In this review, we provide a comprehensive overview of different principle mechanisms of drug hepatotoxicity and illustrate how patient-specific factors, such as genetic, physiological and environmental factors, can shape drug responses. Furthermore, we highlight other parameters, such as concomitantly prescribed medications or liver diseases and how they modulate drug toxicity, pharmacokinetics and dynamics. Finally, we discuss recent progress in the field of in vitro toxicity models and evaluate their utility in reflecting patient-specific factors to study inter-individual differences in drug response and toxicity, as this understanding is necessary to pave the way for a patient-adjusted medicine.

Cost-Effectiveness of Pharmacogenomic and Pharmacogenetic Test-Guided Personalized Therapies: A Systematic Review of the Approved Active Substances for Personalized Medicine in Germany

BACKGROUND

The use of targeted therapies has recently increased. Pharmacogenetic tests are a useful tool to guide patient treatment and to test a response before administering medicines. Pharmacogenetic tests can predict potential drug resistance and may be used for determining genotype-based drug dosage. However, their cost-effectiveness as a diagnostic tool is often debatable. In Germany, 47 active ingredients are currently approved. A prior predictive test is required for 39 of these and is recommended for eight. The objective of this study was to review the cost-effectiveness (CE) of pharmacogenetic test-guided drug therapy and compare the application of drugs with and without prior genetic testing.

METHODS

A systematic literature review was conducted to identify the CE and cost-utility of genetic tests. Studies from January 2000 until November 2015 were searched in 16 databases including Medline, Embase, and Cochrane. A quality assessment of the full-text publications was performed using the validated Quality of Health Economic Studies (QHES) instrument.

RESULTS

In the majority of the included studies, the pharmacogenetic test-guided therapy represents a cost-effective/cost-saving treatment option. Only seven studies lacked a clear statement of CE or cost-savings, because of uncertainty, restriction to specific patient populations, or assumptions for comparative therapy. Moreover, the high quality of the available evidence was evaluated.

CONCLUSION

Pharmacogenetic testing constitutes an opportunity to improve the CE of pharmacotherapy. The CE of targeted therapies depends on various factors including costs, prevalence of biomarkers, and test sensitivity and specificity. To guarantee the CE comparability of stratified drug therapies, national and international standards for evaluation studies should be defined.

Role of pharmacogenetics in public health and clinical health care: a SWOT analysis

Pharmacogenomics has been lauded as an important innovation in clinical medicine as a result of advances in genomic science. As one of the cornerstones in precision medicine, the vision to determine the right medication in the right dosage for the right treatment with the use of genetic information has not exactly materialised, and few genetic tests have been implemented as the standard of care in health systems worldwide. Here we review the findings from a SWOT analysis to examine the strengths, weaknesses, opportunities and threats around the role of pharmacogenetics in public health and clinical health care, at the micro, meso and macro levels corresponding to the perspectives of the individuals (scientists, patients and physicians), the health-care institutions and the health systems, respectively.

A Systematic Review of Economic Evaluations of Pharmacogenetic Testing for Prevention of Adverse Drug Reactions

BACKGROUND

Pharmacogenetics offers the potential to improve health outcomes by identifying individuals who are at greater risk of harm from certain medicines. Routine adoption of pharmacogenetic tests requires evidence of their cost effectiveness.

OBJECTIVE

The present review aims to systematically review published economic evaluations of pharmacogenetic tests that aim to prevent or reduce the incidence of ADRs.

METHODS

We conducted a systematic literature review of economic evaluations of pharmacogenetic tests aimed to reduce the incidence of adverse drug reactions. Literature was searched using Embase, MEDLINE and the NHS Economic Evaluation Database with search terms relating to pharmacogenetic testing, adverse drug reactions, economic evaluations and pharmaceuticals. Titles were screened independently by two reviewers. Articles deemed to meet the inclusion criteria were screened independently on abstract, and full texts reviewed.

RESULTS

We identified 852 articles, of which 47 met the inclusion criteria. There was evidence supporting the cost effectiveness of testing for HLA-B*57:01 (prior to abacavir), HLA-B*15:02 and HLA-A*31:01 (prior to carbamazepine), HLA-B*58:01 (prior to allopurinol) and CYP2C19 (prior to clopidogrel treatment). Economic evidence was inconclusive with respect to TPMT (prior to 6-mercaptoputine, azathioprine and cisplatin therapy), CYP2C9 and VKORC1 (to inform genotype-guided dosing of coumarin derivatives), MTHFR (prior to methotrexate treatment) and factor V Leiden testing (prior to oral contraception). Testing for A1555G is not cost effective before prescribing aminoglycosides.

CONCLUSIONS

Our systematic review identified robust evidence of the cost effectiveness of genotyping prior to treatment with a number of common drugs. However, further analyses and (or) availability of robust clinical evidence is necessary to make recommendations for others.

MinION: A Novel Tool for Predicting Drug Hypersensitivity?

The launch of the MinION Access Program has caused much activity within the scientific community. MinION represents a keenly anticipated, novel addition to the current melange of commercial sequencers. Driven by the nanopore sequencing mechanism that requires minimal sample manipulation, the device is capable of generating long sequence reads in sizes (up to or exceeding 50 kb) that surpass those of all other platforms. One notable advantage of this feature is that long-range haplotypes can be more accurately resolved; such advantage is particularly pertinent to the genotyping of complex loci such as genes encoding the human leukocyte antigens, which are pivotal determinants of drug hypersensitivity. With this timely, albeit brief, review, we set out to examine the applications on which MinION has been tested thus far, the bioinformatics workflow tailored to the unique characteristics of its extended sequence reads, the device’s potential utility in the detection of genetic markers for drug hypersensitivity, and how it may eventually evolve to become fit for diagnostic purposes in the clinical setting.

Assessment of pharmacogenetic tests: presenting measures of clinical validity and potential population impact in association studies

The progressing discovery of genetic variants associated with drug-related adverse events has raised expectations for pharmacogenetic tests to improve drug efficacy and safety. To further the use of pharmacogenetics in health care, tests with sufficient potential to improve efficacy and safety, as reflected by good clinical validity and population impact, need to be identified. The potential benefit of pharmacogenetic tests is often concluded from the strength of the association between the variant and the adverse event; measures of clinical validity are generally not reported. This paper describes measures of clinical validity and potential population health impact that can be calculated from association studies. We explain how these measures are influenced by the strength of the association and by the frequencies of the variant and the adverse event. The measures are illustrated using examples of testing for HLA-B*5701 associated with abacavir-induced hypersensitivity and SLCO1B1 c.521T>C (*5) associated with simvastatin-induced adverse events.

Economic Evaluations of Pharmacogenetic and Pharmacogenomic Screening Tests: A Systematic Review. Second Update of the Literature

Objective

Due to extended application of pharmacogenetic and pharmacogenomic screening (PGx) tests it is important to assess whether they provide good value for money. This review provides an update of the literature.

Methods

A literature search was performed in PubMed and papers published between August 2010 and September 2014, investigating the cost-effectiveness of PGx screening tests, were included. Papers from 2000 until July 2010 were included via two previous systematic reviews. Studies’ overall quality was assessed with the Quality of Health Economic Studies (QHES) instrument.

Results

We found 38 studies, which combined with the previous 42 studies resulted in a total of 80 included studies. An average QHES score of 76 was found. Since 2010, more studies were funded by pharmaceutical companies. Most recent studies performed cost-utility analysis, univariate and probabilistic sensitivity analyses, and discussed limitations of their economic evaluations. Most studies indicated favorable cost-effectiveness. Majority of evaluations did not provide information regarding the intrinsic value of the PGx test. There were considerable differences in the costs for PGx testing. Reporting of the direction and magnitude of bias on the cost-effectiveness estimates as well as motivation for the chosen economic model and perspective were frequently missing.

Conclusions

Application of PGx tests was mostly found to be a cost-effective or cost-saving strategy. We found that only the minority of recent pharmacoeconomic evaluations assessed the intrinsic value of the PGx tests. There was an increase in the number of studies and in the reporting of quality associated characteristics. To improve future evaluations, scenario analysis including a broad range of PGx tests costs and equal costs of comparator drugs to assess the intrinsic value of the PGx tests, are recommended. In addition, robust clinical evidence regarding PGx tests’ efficacy remains of utmost importance.

Prevalence of HLA-B*5701 and Its Relationship with Abacavir Hypersensitivity Reaction in Iranian HIV-Infected Patients

BACKGROUND

Hypersensitivity reaction (HSR) is a major adverse effect of abacavir (ABC), which occurs in 5-8% of Caucasians. The relationship between Human Leukocyte Antigen (HLA) and ABC HSR has been reported in various populations. It has been proposed to administer ABC only to HLA-B*5701 negative patients to avoid this reaction. The purpose of this study was to assess the prevalence of HLA-B*5701 in Iranian HIV positive patients. We also sought to find the relationship between this allele with ABC HSR in patients who received the medication.

MATERIALS AND METHODS

We screened patients for HLA-B*5701 allele using SybrGreen real time PCR-melting method on blood samples from HIV positive patients who were referred to our hospital. The quality of the extracted genome was evaluated by B-globin housekeeping gene as internal control prior to HLA-B*5701 allele screening.

RESULTS

Of 198 HIV-infected patients, 6 (3.0%) had the HLA-B*5701 allele (95% CI, 1%-5%). Among the 28 patients who were given ABC, one individual had the HLA-B*5701 allele and experienced ABC HSR.

CONCLUSION

Prevalence of HLA-B*5701 in Iranian patients was lower than that in Caucasians but was comparable with that of other Middle Eastern populations. Screening for HLA-B*5701 before ABC administration as part of antiretroviral therapy may reduce the risk of HSR.

The value of routine pharmacogenomic screening-Are we there yet? A perspective on the costs and benefits of routine screening-shouldn't everyone have this done?

Although there are several examples in which pharmacogenomic testing seems to provide clinical and economic value, use of pharmacogenomics as a tool to improve drug therapy through routine screening of unselected patients is currently tentative. An informal evaluation of the clinical benefits and economic costs of pharmacogenomic screening suggests that improving the evidence base, addressing uncertainty, and facilitating implementation can lead to practical and cost-effective pharmacogenomic screening programs.

Cost-effectiveness analysis of tenofovir/emtricitabine and abacavir/lamivudine in combination with efavirenz or atazanavir/ritonavir for treatment-naïve adults with HIV-1 infection in the UK, based on the AIDS Clinical Trials Group 5202 clinical trial

OBJECTIVES

The aim of the study was to assess the cost-effectiveness of the four regimens studied in the AIDS Clinical Trials Group (ACTG) 5202 clinical trial, tenofovir/emtricitabine (TDF/FTC) or abacavir/lamivudine (ABC/3TC) in combination with efavirenz (EFV) or atazanavir/ritonavir (ATV/r), for treatment-naïve adults with HIV-1 infection in the UK.

METHODS

A Markov model with six health states based on CD4 cell count ranges was developed to predict long-term costs and health outcomes for individuals on first-line therapy. Head-to-head efficacy data comparing TDF/FTC + EFV, TDF/FTC + ATV/r, ABC/3TC + EFV, and ABC/3TC + ATV/r were obtained from ACTG 5202 for up to 192 weeks. Antiretroviral drug costs were based on current list prices. Other medical costs (2013 UK pounds sterling), utility values, and mortality rates were obtained from published sources. Base-case, sensitivity, and subgroup analyses (by baseline viral load) were conducted.

RESULTS

Individuals using TDF/FTC-based regimens were predicted to remain on first-line therapy longer and accrue more quality-adjusted life-years (QALYs) than individuals using ABC/3TC-based regimens. At a willingness-to-pay threshold of £30 000 per QALY gained, TDF/FTC-based regimens were predicted to be cost-effective compared with ABC/3TC-based regimens, with incremental cost-effectiveness ratios of £23 355 for TDF/FTC + EFV vs. ABC/3TC + EFV and £23 785 for TDF/FTC + ATV/r vs. ABC/3TC + ATV/r. Results were generally robust in subgroup, sensitivity, and scenario analyses.

CONCLUSIONS

In an analysis of the regimens studied in ACTG 5202 for treatment-naïve adults with HIV-1 infection in the UK, TDF/FTC-based regimens yielded more favourable health outcomes and were generally predicted to be cost-effective compared with ABC/3TC-based regimens. These results confirm that TDF/FTC-based regimens are not only clinically effective but also cost-effective.

Cost-effectiveness of CYP2B6 genotyping to optimize efavirenz dosing in HIV clinical practice

AIMS

To assess the cost-effectiveness of CYP2B6 genotyping to guide efavirenz dosing for initial HIV therapy in the USA.

METHODS

We used the Cost-Effectiveness of Preventing AIDS Complications (CEPAC) microsimulation model to project quality-adjusted life expectancy and lifetime costs (2014 US dollars) for efavirenz-based HIV therapy with or without CYP2B6 genotyping. We assumed that with genotyping 60% of patients would be eligible to receive lower doses.

RESULTS

Current care without CYP2B6 genotyping has an incremental cost-effectiveness ratio >$100,000/QALY compared with genotype-guided dosing, even if lower dosing reduces efficacy. When we assumed generic efavirenz availability, conclusions were similar unless lower dosing reduces efficacy by 6% or more.

CONCLUSION

CYP2B6 genotyping can inform efavirenz dosing and decrease HIV therapy cost.

New genetic findings lead the way to a better understanding of fundamental mechanisms of drug hypersensitivity

Drug hypersensitivity reactions are an important clinical problem for both health care and industry. Recent advances in genetics have identified a number of HLA alleles associated with a range of these adverse reactions predominantly affecting the skin but also other organs, such as the liver. The associations between abacavir hypersensitivity and HLA-B*57:01 and carbamazepine-induced Stevens-Johnson syndrome and HLA-B*15:02 have been implemented in clinical practice. There are many different mechanisms proposed in the pathogenesis of drug hypersensitivity reactions, including the hapten hypothesis, direct binding to T-cell receptors (the pharmacologic interaction hypothesis), and peptide-binding displacement. A problem with all the hypotheses is that they are largely based on in vitro findings, with little direct in vivo evidence. Although most studies have focused on individual mechanisms, it is perhaps more important to consider them all as being complementary, potentially occurring at the same time with the same drug in the same patient. This might at least partly account for the heterogeneity of the immune response seen in different patients. There is a need to develop novel methodologies to evaluate how the in vitro mechanisms relate to the in vivo situation and how the highly consistent genetic findings with different HLA alleles can be more consistently used for both prediction and prevention of these serious adverse reactions.

Perspectives on pharmacogenomics of antiretroviral medications and HIV-associated comorbidities

PURPOSE OF REVIEW

To summarize current knowledge and provide perspective on relationships between human genetic variants, antiretroviral medications, and aging-related complications of HIV-1 infection.

RECENT FINDINGS

Human genetic variants have been convincingly associated with interindividual variability in antiretroviral toxicities, drug disposition, and aging-associated complications in HIV-1 infection. Screening for HLA-B5701 to avoid abacavir hypersensitivity reactions has become a routine part of clinical care, and has markedly improved drug safety. There are well established pharmacogenetic associations with other agents (efavirenz, nevirapine, atazanavir, dolutegravir, and others), but this knowledge has yet to have substantial impact on HIV-1 clinical care. As metabolic complications including diabetes mellitus, dyslipidemia, osteoporosis, and cardiovascular disease are becoming an increasing concern among individuals who are aging with well controlled HIV-1 infection, human genetic variants that predispose to these complications also become more relevant in this population.

SUMMARY

Pharmacogenetic knowledge has already had considerable impact on antiretroviral prescribing. With continued advances in the field of human genomics, the impact of pharmacogenomics on HIV-1 clinical care and research is likely to continue to grow in importance and scope.

Comparative analysis between saliva and buccal swabs as source of DNA: lesson from HLA-B*57:01 testing

AIM

Our work aimed to designate the optimal DNA source for pharmacogenetic assays, such as the screening for HLA-B*57:01 allele.

MATERIALS & METHODS

A saliva and four buccal swab samples were taken from 104 patients. All the samples were stored at different time and temperature conditions and then genotyped for the HLA-B*57:01 allele by SSP-PCR and classical/capillary electrophoresis.

RESULTS

The genotyping analysis reported different performance rates depending on the storage conditions of the samples. Given our results, the buccal swab demonstrated to be more resistant and stable in time with respect to the saliva.

CONCLUSION

Our investigation designates the buccal swab as the optimal DNA source for pharmacogenetic assays in terms of resistance, low infectivity, low-invasiveness and easy sampling, and safe transport in centralized medical centers providing specialized pharmacogenetic tests.

Market Access Advancements and Challenges in "Drug-Companion Diagnostic Test" Co-Development in Europe

The pharma ecosphere is witnessing a measured transformation from the one-size-fits-all or blockbuster model of drugs to more informed and tailored personalized treatments that facilitate higher safety and efficacy for a relevant sub-population. However, with several breakthroughs still in a nascent stage, market access becomes a crucial factor for commercial success, especially when it comes to co-creating value for pertinent stakeholders. This article highlights diverse issues from stakeholder perspectives in Europe, specifically the ones which require immediate resolution. Furthermore, the article also discusses case studies articulating potential solutions for the issues discussed.

Role of dermatology in pharmacogenomics: drug-induced skin injury

Different individuals may respond diversely to the same drug, in terms of efficacy and toxicity. Adverse drug reactions cause about 6% of all hospital admissions and account for up to 9% of hospitalization costs. Drug-induced skin injury (DISI) is the most common presentation of adverse drug reactions, ranging from maculopapular eruptions to severe adverse cutaneous drug reactions (SCARs) with mortality of up to 40%. Specific genetic polymorphisms confer susceptibility to different types of DISI. Identifying patients genetically at risk for SCARs is one of the goals of pharmacogenomics. In this article, the aspects of clinical dermatology relevant to the pharmacogenetics of DISI are reviewed. Many SCARs are now preventable, with consequent reduction of morbidity, mortality and healthcare costs.

Antiviral drug allergy

Antiviral drugs used to treat HIV and hepatitis C are common causes of delayed drug hypersensitivities for which many of the more severe reactions have been recently shown to be immunogenetically mediated such as abacavir hypersensitivity where HLA-B(∗)57:01 is now used routinely as a screening test to exclude patients carrying this allele from abacavir prescription. Most antiviral drug allergies consist of mild to moderate delayed rash without other serious features (eg, fever, mucosal involvement, blistering rash, organ impairment. In these cases treatment can be continued with careful observation and symptomatic management and the discontinuation rate is low.

Diagnostic accuracy of HLA-B*57:01 screening for the prediction of abacavir hypersensitivity and clinical utility of the test: a meta-analytic review

AIM

To determine diagnostic accuracy of HLA-B*57:01 testing for prediction of abacavir-induced hypersensitivity and to quantify the clinical benefit of pretreatment screening through a meta-analytic review of published studies.

METHODS

A comprehensive search was performed up to June 2013. The methodological quality of relevant studies was assessed by the QUADAS-2 tool. The pooled diagnostic estimates were calculated using a random effect model.

RESULTS

Despite the presence of heterogeneity in sensitivity or specificity estimates, the pooled diagnostic odds ratio to detect abacavir-induced hypersensitivity on the basis of clinical criteria was 33.07 (95% CI: 22.33-48.97, I(2): 13.9%), while diagnostic odds ratio for detection of immunologically confirmed abacavir hypersensitivity was 1141 (95% CI: 409-3181, I(2): 0%). Pooled analysis of risk ratio showed that prospective HLA-B*57:01 testing significantly reduced the incidence of abacavir-induced hypersensitivity.

CONCLUSION

This meta-analysis demonstrates an excellent diagnostic accuracy of HLA-B*57:01 testing to detect immunologically confirmed abacavir hypersensitivity and corroborates existing recommendations.

Pharmacogenetic biomarkers for predicting drug response

Drug response shows significant interpatient variability and evidence that genetics influences outcome of drug therapy has been known for more than five decades. However, the translation of this knowledge to clinical practice remains slow. Using examples from clinical practice six considerations about the implementation of pharmacogenetics (PGx) into routine care are discussed: the need for PGx biomarkers; the sources of genetic variability in drug response; the amount of variability explained by PGx; whether PGx test results are actionable; the level of evidence needed for implementation of PGx and the sources of information regarding interpretation of PGx data.

Fever, rash, and systemic symptoms: understanding the role of virus and HLA in severe cutaneous drug allergy

Drug hypersensitivity syndromes such as abacavir hypersensitivity and the severe cutaneous adverse drug reactions have been associated with significant short- and long-term morbidity and mortality. More recently, these immunologically mediated and previously unpredictable diseases have been shown to be associated with primarily class I but also class II HLA alleles. The case of the association of HLA-B*57:01 and abacavir hypersensitivity has created a translational roadmap for how this knowledge can be used in the clinic to prevent severe reactions. Although many hurdles exist to the widespread translation of such HLA screening approaches, our understanding of how drugs interact with the major histocompatibility complex has contributed to the discovery of new models that have provided considerable insights into the immunopathogenesis of severe cutaneous adverse drug reactions and other T-cell-mediated drug hypersensitivity syndromes. Future translation of this knowledge will facilitate the development of preclinical toxicity screening to significantly improve efficacy and safety of drug development and design.

Genotyping for severe drug hypersensitivity

Over the past decade, there have been significant advances in our understanding of the immunopathogenesis and pharmacogenomics of severe immunologically-mediated adverse drug reactions. Such T-cell-mediated adverse drug reactions such as Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), drug-induced liver disease (DILI) and other drug hypersensitivity syndromes have more recently been shown to be mediated through interactions with various class I and II HLA alleles. Key examples have included the associations of HLA-B*15:02 and carbamazepine induced SJS/TEN in Southeast Asian populations and HLA-B*57:01 and abacavir hypersensitivity. HLA-B*57:01 screening to prevent abacavir hypersensitivity exemplifies a successful translational roadmap from pharmacogenomic discovery through to widespread clinical implementation. Ultimately, our increased understanding of the interaction between drugs and the MHC could be used to inform drug design and drive pre-clinical toxicity programs to improve drug safety.