Cost impact of prospective HLA-B*5701-screening prior to abacavir/lamivudine fixed dose combination use in Germany

HLA-B*57:01 typing in a Malaysian cohort: implications of abacavir hypersensitivity in people living with HIV

Background: Abacavir (ABC) in combination with other antiretroviral drugs, is used to treat people living with HIV (PLWH). However, it is linked to a fatal hypersensitivity reaction in susceptible individuals, and is strongly associated with the HLA-B*57:01 allele. Materials & methods: A total of 152 patients, 50 PLWH and 102 HIV-1 negative patients, were assessed for the HLA-B*57:01 allele through a sequence-specific primer PCR. Results: All PLWH tested negative for the HLA-B*57:01 allele, but two HIV-negative patients were found to have HLA-B*57, with one of them expressing the HLA-B*57:01 allele. Conclusion: Given the low prevalence of this risk allele in the population, testing for the presence of HLA-B*57:01 in PLWH may not provide significant benefit for the reported population.

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.

Severe abacavir hypersensitivity reaction in a patient with human immunodeficiency virus infection: a case report

Background

Abacavir is a nucleoside reverse transcriptase inhibitor that is used as a component of the antiretroviral treatment regimen in the management of the human immunodeficiency virus for both adults and children. It is efficacious, but its use may be limited by a hypersensitivity reaction linked with the HLA-B*57:01 genotype. HLA-B*57:01 has been reported to be rare in African populations. Because of the nature of its presentation, abacavir hypersensitivity is prone to late diagnosis and treatment, especially in settings where HLA-B*57:01 genotyping is not routinely done.

Case report

We report a case of a severe hypersensitivity reaction in a 44-year-old Kenyan female living with the human immunodeficiency virus and on abacavir-containing antiretroviral therapy. The patient presented to the hospital after recurrent treatment for a throat infection with complaints of fever, headache, throat ache, vomiting, and a generalized rash. Laboratory results evidenced raised aminotransferases, for which she was advised to stop the antiretrovirals that she had recently been started on. The regimen consisted of abacavir, lamivudine, and dolutegravir. She responded well to treatment but was readmitted a day after discharge with vomiting, severe abdominal pains, diarrhea, and hypotension. Her symptoms disappeared upon admission, but she was readmitted again a few hours after discharge in a hysterical state with burning chest pain and chills. Suspecting abacavir hypersensitivity, upon interrogation she reported that she had taken the abacavir-containing antiretrovirals shortly before she was taken ill. A sample for HLA-B*57:01 was taken and tested positive. Her antiretroviral regimen was substituted to tenofovir, lamivudine, and dolutegravir, and on subsequent follow-up she has been well.

Conclusions

Clinicians should always be cognizant of this adverse reaction whenever they initiate an abacavir-containing therapy. We would recommend that studies be done in our setting to verify the prevalence of HLA-B*57:01.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13256-022-03647-6.

Economic Evaluation of Multiple-Pharmacogenes Testing for the Prevention of Adverse Drug Reactions in People Living with HIV

Purpose

Pharmacogenetics (PGx) testing is one of the methods for determining whether individuals are at risk of adverse drug reactions (ADRs). It has been reported that multiple-PGx testing, a sequencing technology, has a higher predictive value than single-PGx testing. Therefore, this study aimed to determine the most cost-effective PGx testing strategies for preventing drug-induced serious ADRs in human immunodeficiency virus (HIV)-infected patients.

Patients and Methods

Potential strategies, including 1) single-PGx esting (ie, HLA-B*57:01 testing before prescribing abacavir, HLA-B*13:01 testing before prescribing co-trimoxazole and dapsone, and NAT2 testing before prescribing isoniazid) and 2) multiple-PGx testing as a combination of four single-gene PGx tests in one panel, were all compared to no PGx testing (current practice). To evaluate total cost in Thai baht (THB) and quality-adjusted life years (QALYs) for each strategy-based approach to a societal perspective, a hybrid decision tree and Markov model was constructed. Incremental cost-effectiveness ratios (ICERs) were estimated. Uncertainty, threshold, and scenario analyses were all performed.

Results

Before prescribing HIV therapy, providing single or multiple-PGx testing might save roughly 68 serious ADRs per year, and the number needed to screen (NNS) to avoid one serious ADR was 40. Consequently, approximately 35% and 40% of the cost of ADR treatment could be avoided by the implementation of single- and multiple-PGx testing, respectively. Compared with no PGx testing strategy, the ICERs were 146,319 THB/QALY gained for single-PGx testing and 152,014 THB/QALY gained for multiple-PGx testing. Moreover, the probability of multiple-PGx testing being cost-effective was 45% at the Thai willingness to pay threshold of 160,000 THB per QALY. Threshold analyses showed that multiple-PGx testing remained cost-effective under the range of cost, sensitivity at 0.95–1.00 and specificity at 0.98–1.00.

Conclusion

Single and multiple-PGx testing might be cost-effective options for reducing the incidence of drug-induced serious ADRs in people living with HIV.

Genotyping for HLA Risk Alleles to Prevent Drug Hypersensitivity Reactions: Impact Analysis

Human Leukocyte Antigen (HLA) variants can be a risk factor for developing potentially fatal drug hypersensitivity reactions. Our aim was to estimate the potential impact of genotyping for the HLA risk alleles incorporated in the Dutch Pharmacogenetics Working Group (DPWG) guidelines in The Netherlands. We estimated the number of hypersensitivity reactions and associated deaths that can be avoided annually by genotyping for these HLA risk alleles. Additionally, the cost-effectiveness was estimated. Nationwide implementation of genotyping HLA risk alleles before initiating drugs with an actionable drug-gene interaction can potentially save the life of seven allopurinol initiators and two flucloxacillin initiators each year in The Netherlands. Besides these deaths, 28 cases of abacavir hypersensitivity, 24 cases of allopurinol induced SCARs, 6 cases of carbamazepine induced DRESS and 22 cases of flucloxacillin induced DILI can be prevented. Genotyping HLA-B*5701 in abacavir initiators has a number needed to genotype of 31 to prevent one case of abacavir hypersensitivity and is cost-saving. Genotyping HLA-B*5801 in allopurinol initiators has a number needed to genotype of 1149 to prevent one case of SCAR but is still cost-effective. Genotyping before initiating antiepileptic drugs or flucloxacillin is not cost-effective. Our results confirm the need for mandatory testing of HLA-B*5701 in abacavir initiators, as indicated in the drug label, and show genotyping of HLA-B*5801 in allopurinol initiators should be considered.

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.

Challenges and Opportunities in Implementing Pharmacogenetic Testing in Clinical Settings

The clinical implementation of pharmacogenetic biomarkers continues to grow as new genetic variants associated with drug outcomes are discovered and validated. The number of drug labels that contain pharmacogenetic information also continues to expand. Published, peer-reviewed clinical practice guidelines have also been developed to support the implementation of pharmacogenetic tests. Incorporating pharmacogenetic information into health care benefits patients as well as clinicians by improving drug safety and reducing empiricism in drug selection. Barriers to the implementation of pharmacogenetic testing remain. This review explores current pharmacogenetic implementation initiatives with a focus on the challenges of pharmacogenetic implementation and potential opportunities to overcome these challenges.

Novel genetic and epigenetic factors of importance for inter-individual differences in drug disposition, response and toxicity

Individuals differ substantially in their response to pharmacological treatment. Personalized medicine aspires to embrace these inter-individual differences and customize therapy by taking a wealth of patient-specific data into account. Pharmacogenomic constitutes a cornerstone of personalized medicine that provides therapeutic guidance based on the genomic profile of a given patient. Pharmacogenomics already has applications in the clinics, particularly in oncology, whereas future development in this area is needed in order to establish pharmacogenomic biomarkers as useful clinical tools. In this review we present an updated overview of current and emerging pharmacogenomic biomarkers in different therapeutic areas and critically discuss their potential to transform clinical care. Furthermore, we discuss opportunities of technological, methodological and institutional advances to improve biomarker discovery. We also summarize recent progress in our understanding of epigenetic effects on drug disposition and response, including a discussion of the only few pharmacogenomic biomarkers implemented into routine care. We anticipate, in part due to exciting rapid developments in Next Generation Sequencing technologies, machine learning methods and national biobanks, that the field will make great advances in the upcoming years towards unlocking the full potential of genomic data.

An update on HLA alleles associated with adverse drug reactions

Adverse drug reactions (ADRs) are considered as an important cause of morbidity and mortality. The hypersensitivity reactions are immune-mediated ADRs, which are dose-independent, unpredictable and have been associated with several HLA alleles. The present review aimed to describe HLA alleles that have been associated with different ADRs in populations worldwide, the recommendations of regulatory agencies and pharmacoeconomic information and databases for the study of HLA alleles in pharmacogenetics. A systematic search was performed in June 2016 of articles relevant to this issue in indexed journals and in scientific databases (PubMed and PharmGKB). The information of 95 association studies found was summarized. Several HLA alleles and haplotypes have been associated with ADRs induced mainly by carbamazepine, allopurinol, abacavir and nevirapine, among other drugs. Years with the highest numbers of publications were 2013 and 2014. The majority of the reports have been performed on Asians and Caucasians, and carbamazepine was the most studied ADR drug inducer. Two HLA alleles' databases are described, as well as the recommendations of the U.S. Food and Drug Administration, the European Medicine Agency and the Clinical Pharmacogenetics Implementation Consortium. Pharmacoeconomic studies on this issue are also mentioned. The strongest associations remain for HLA-B*58:01, HLA-B*57:01, HLA-B*15:02 and HLA-A*31:01 but only in certain populations; therefore, studies on different ethnic groups would be useful. Due to the improvement of drug therapy and the economic benefit that HLA screening represents, investigations on HLA alleles associated with ADR should continue.

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.

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.

Economic Evaluations of Pharmacogenetic Approaches in Infectious Diseases: A Review of Current Approaches and Evaluation of Critical Aspects Affecting their Quality

Pharmacogenetics holds great potential for improving the effectiveness of treatment modalities in infectious diseases by taking into account the genetic determinants of both the host and infectious agents' individuality. Better utilization of resources and improved therapeutic efficiency are the expected outcomes of personalized medicine using pharmacogenetic and pharmacogenomics information made available by technological advances. However, there has been growing concern in the clinical community regarding the evaluation of the true benefits of these approaches. This perception is partly due to the limited number and perceived poor quality of economic evaluations in this field, and initiatives aimed at harmonizing and communicating strategies improving the quality of these studies and their acceptance by the clinical community are greatly needed. This paper reviews current literature of economic evaluations of pharmacogenetics interventions guiding pharmacotherapy in infectious diseases. PubMed and the NHS Centre for Reviews and Dissemination databases were searched using a combination of five broad research terms related to pharmacogenetic approaches, and papers relative to economic evaluations of pharmacogenetic interventions in infectious diseases retained for further analysis. Using these criteria, a total of 14 papers were included in this review. The area of economic evaluation of pharmacogenetic interventions in infectious diseases remains understudied and would benefit from greater harmonization. The main weaknesses of evaluations reviewed in this paper seem to be represented by poor evidence of pharmacogenetic marker validation, inconsistencies in the selection of costs and utility included in the economic models and the choice of sensitivity analysis. All these factors limit the overall transparency of the studies, greater acceptance of their results and applicability to diverse and possibly resourcelimited environments where these approaches could be expected to have the greater impact.

Pharmacogenetic testing: Current Evidence of Clinical Utility

Over the last decade, the number of clinical pharmacogenetic tests has steadily increased as understanding of the role of genes in drug response has grown. However, uptake of these tests has been slow, due in large part to the lack of robust evidence demonstrating clinical utility. We review the evidence behind four pharmacogenetic tests and discuss the barriers and facilitators to uptake: 1) warfarin (drug safety and efficacy); 2) clopidogrel (drug efficacy); 3) codeine (drug efficacy); and 4) abacavir (drug safety). Future efforts should be directed toward addressing these issues and considering additional approaches to generating evidence basis to support clinical use of pharmacogenetic tests.

HLA and pharmacogenetics of drug hypersensitivity

Immunologically mediated drug reactions have been traditionally classified as unpredictable based on the fact that they cannot be predicted strictly on the pharmacological action of the drug. Such adverse drug reactions are associated with considerable morbidity and include severe cutaneous adverse reactions such as Stevens-Johnson syndrome/toxic epidermal necrolysis and the drug hypersensitivity syndromes (drug reaction with eosinophilia and systemic symptoms/drug-induced hypersensitivity syndrome). Over the last decade there have been many associations between these syndromes and Class I and II HLA alleles of the MHC, which have enriched and driven our knowledge of their immunopathogenesis. Significant translation has also occurred in the case of HLA-B*5701 screening being used to exclude at risk patients from abacavir and prevent abacavir hypersensitivity. The ultimate translation of the knowledge of how drugs interact with HLA would be applicable to preclinical drug screening programs to improve the safety and cost-effectiveness of drug design and development.

Prevalence of human leukocyte antigen-B*5701 among HIV-infected children in Thailand and Cambodia: implications for abacavir use

Human leukocyte antigen (HLA)-B*5701 allele is associated with abacavir hypersensitivity. Limited data among Asians showed lower rates of HLA-B*5701 compared with Caucasians. In 296 children with HIV in Thailand and Cambodia, the prevalence of HLA-B*5701 was 4.0% (95% confidence interval: 1.6-8.0%) among Thai and 3.4% (95% confidence interval: 0.9-8.5%) among Cambodian children. HLA-B*5701 carriage is not uncommon among Thai and Cambodian children; it is close to the prevalence found in European and higher than the prevalence found in East Asian and African studies.