Studies on abacavir-induced hypersensitivity reaction: a successful example of translation of pharmacogenetics to personalized medicine

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.

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.

A Comprehensive Review of HLA and Severe Cutaneous Adverse Drug Reactions: Implication for Clinical Pharmacogenomics and Precision Medicine

Human leukocyte antigen (HLA) encoded by the HLA gene is an important modulator for immune responses and drug hypersensitivity reactions as well. Genetic polymorphisms of HLA vary widely at population level and are responsible for developing severe cutaneous adverse drug reactions (SCARs) such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), maculopapular exanthema (MPE). The associations of different HLA alleles with the risk of drug induced SJS/TEN, DRESS and MPE are strongly supportive for clinical considerations. Prescribing guidelines generated by different national and international working groups for translation of HLA pharmacogenetics into clinical practice are underway and functional in many countries, including Thailand. Cutting edge genomic technologies may accelerate wider adoption of HLA screening in routine clinical settings. There are great opportunities and several challenges as well for effective implementation of HLA genotyping globally in routine clinical practice for the prevention of drug induced SCARs substantially, enforcing precision medicine initiatives.

HLA-B*57:01 allele prevalence in treatment-Naïve HIV-infected patients from Colombia

BACKGROUND

The HLA-B*57:01 allele is associated with a hypersensitivity reaction to abacavir. Due to the lack of knowledge of HLA-B*57:01 prevalence in Colombia, routine screening is not performed and is not recommended by the national guidelines. We aimed to determine the prevalence of HLA-B*57:01 in HIV population from Colombia.

METHODS

This cross-sectional study included naïve HIV-infected adults from 13 cities of the country. The presence of HLA-B*57:01 was determined by using SSP-PCR in blood samples. Prevalence rates were stratified by sex, race, and region of origin.

RESULTS

HLA-B*57:01 allele prevalence in Colombian HIV-infected individuals was 2.7%. When stratifying for the race, the prevalence was 4% for whites, 2.6% for other race (mainly mestizo), and 1.9% for Afro-Colombians. The prevalence varied from 0% up to 11.4% depending on the department of origin. The highest prevalence rates were found in Caldas (11.4%), Antioquia (5%), Risaralda (4.8%), and Valle del Cauca (4.3%). When distributed by country zones, the central, with a racial predominance of Caucasians and mestizos, was the highest (6.0%, 0R = 4.1, CI 1.2-12.8, p = 0,016).

CONCLUSIONS

The overall prevalence of HLA-B*57:01 in Colombia was lower than the reported rates for other Latin American countries such as Brazil, Costa Rica, and Argentina, but similar in comparison to Chile and Mexico. The diversity in the racial and ethnic heritage shown in our data supports the recommendation to implement routine screening for the HLA-B*57:01 allele before initiation of abacavir-containing antiretroviral therapy in the Colombian HIV management guidelines.

Sequencing XMET genes to promote genotype-guided risk assessment and precision medicine

High-throughput next generation sequencing (NGS) is a shotgun approach applied in a parallel fashion by which the genome is fragmented and sequenced through small pieces and then analyzed either by aligning to a known reference genome or by de novo assembly without reference genome. This technology has led researchers to conduct an explosion of sequencing related projects in multidisciplinary fields of science. However, due to the limitations of sequencing-based chemistry, length of sequencing reads and the complexity of genes, it is difficult to determine the sequences of some portions of the human genome, leaving gaps in genomic data that frustrate further analysis. Particularly, some complex genes are difficult to be accurately sequenced or mapped because they contain high GC-content and/or low complexity regions, and complicated pseudogenes, such as the genes encoding xenobiotic metabolizing enzymes and transporters (XMETs). The genetic variants in XMET genes are critical to predicate inter-individual variability in drug efficacy, drug safety and susceptibility to environmental toxicity. We summarized and discussed challenges, wet-lab methods, and bioinformatics algorithms in sequencing "complex" XMET genes, which may provide insightful information in the application of NGS technology for implementation in toxicogenomics and pharmacogenomics.

HPV vaccine and autoimmune diseases: systematic review and meta-analysis of the literature

BACKGROUND

In the literature conflicting opinions are detectable on the onset of adverse events as autoimmune disease post HPV vaccine and often case reports describes the onset of one of these events, but don't emerge a clear relationship and we don't have data to support it.

METHODS

We carried out a systematic review to identify all scientific publications dealing with the correlation between vaccine anti-papillomavirus and new onset of autoimmune diseases. We searched the main scientific databases (PubMed, Sciverse Scopus, Web of knowledge and Cochrane Central Register of Controlled Clinical Trials) for the following search terms: "vaccine"; "anti-papillomavirus"; "autoimmune"; "disease"; "disorder". To evaluate the safety of HPV vaccines, the dichotomous data on the number of subjects experiencing an autoimmune disorder in the study vaccine group and the placebo group were extracted from each study with subsequent determination of the risk ratios and their 95% confidence intervals. We combined data statistically using a random effects model.

RESULTS

We conduct a meta-analysis on six studies on bivalent and quadrivalent HPV vaccine. The total number of subjects included in the meta-analysis comprised 243,289 in the vaccine group and 248,820 in control groups. Four of the six trials had a Jadad score of 3 or 4 indicating an adequate trial quality. The most frequent autoimmune disease observed across the six studies were musculoskeletal,CNS conditions and endocrinological conditions . The results of the meta-analysis demonstrated no correlation between autoimmune disorders and HPV vaccines (pooled OR 1.038, 95% CI 0.689-1.562).

CONCLUSIONS

No correlation was identified for bivalent and quadrivalent HPV vaccines. It's therefore essential to correctly inform the general population in order to try to increase both Italian and international vaccination coverage.

Impact of New Genomic Technologies on Understanding Adverse Drug Reactions

It is well established that variations in genes can alter the pharmacokinetic and pharmacodynamic profile of a drug and immunological responses to it. Early advances in pharmacogenetics were made with traditional genetic techniques such as functional cloning of genes using knowledge gained from purified proteins, and candidate gene analysis. Over the past decade, techniques for analysing the human genome have accelerated greatly as knowledge and technological capabilities have grown. These techniques were initially focussed on understanding genetic factors of disease, but increasingly they are helping to clarify the genetic basis of variable drug responses and adverse drug reactions (ADRs). We examine genetic methods that have been applied to the understanding of ADRs, review the current state of knowledge of genetic factors that influence ADR development, and discuss how the application of genome-wide association studies and next-generation sequencing approaches is supporting and extending existing knowledge of pharmacogenetic processes leading to ADRs. Such approaches have identified single genes that are major contributing genetic risk factors for an ADR, (such as flucloxacillin and drug-induced liver disease), making pre-treatment testing a possibility. They have contributed to the identification of multiple genetic determinants of a single ADR, some involving both pharmacologic and immunological processes (such as phenytoin and severe cutaneous adverse reactions). They have indicated that rare genetic variants, often not previously reported, are likely to have more influence on the phenotype than common variants that have been traditionally tested for. The problem of genotype/phenotype discordance affecting the interpretation of pharmacogenetic screening and the future of genome-based testing applied to ADRs are also discussed.

Precision or Personalized Medicine for Cancer Chemotherapy: Is there a Role for Herbal Medicine

Although over 100 chemotherapeutic agents are currently available for the treatment of cancer patients, the overall long term clinical benefit is disappointing due to the lack of effectiveness or severe side effects from these agents. In order to improve the therapeutic outcome, a new approach called precision medicine or personalized medicine has been proposed and initiated by the U.S. National Institutes of Health. However, the limited availability of effective medications and the high cost are still the major barriers for many cancer patients. Thus alternative approaches such as herbal medicines could be a feasible and less costly option. Unfortunately, scientific evidence for the efficacy of a majority of herbal medicines is still lacking and their development to meet FDA approval or other regulatory agencies is a big challenge. However, herbal medicines may be able to play an important role in precision medicine or personalized medicine. This review will focus on the existing and future technologies that could speed the development of herbal products for treatment of resistant cancer in individual patients. Specifically, it will concentrate on reviewing the phenotypic (activity based) rather than genotypic (mechanism based) approach to develop herbal medicine useful for personalized cancer chemotherapy.

Adverse events associated with abacavir use in HIV-infected children and adolescents: a systematic review and meta-analysis

BACKGROUND

Concerns exist about the toxicity of drugs used in the implementation of large-scale antiretroviral programmes, and documentation of antiretroviral toxicity is essential. We did a systematic review and meta-analysis of adverse events among children and adolescents receiving regimens that contain abacavir, a widely used antiretroviral drug.

METHODS

We searched bibliographic databases and abstracts from relevant conferences from Jan 1, 2000, to March 1, 2015. All experimental and observational studies of HIV-infected patients aged 0-18 years who used abacavir, were eligible. Incidence of adverse outcomes in patients taking abacavir (number of new events in a period divided by population at risk at the beginning of the study) and relative risks (RR) compared with non-abacavir regimens were pooled with random effects models.

FINDINGS

Of 337 records and 21 conference abstracts identified, nine studies (eight full-text articles and one abstract) collected information about 2546 children, of whom 1769 (69%) were on abacavir regimens. Among children and adolescents taking abacavir, hypersensitivity reactions (eight studies) had a pooled incidence of 2·2% (95% CI 0·4-5·2); treatment switching or discontinuation (seven studies) pooled incidence was 10·9% (2·1-24·3); of grade 3-4 adverse events (six studies) pooled incidence was 9·9% (2·4-20·9); and adverse events other than hypersensitivity reaction (six studies) pooled incidence was 21·5% (2·8-48·4). Between-study inconsistency was significant for all outcomes (p<0·0001 for all inconsistencies). Incidence of death (four studies) was 3·3% (95% CI 1·5-5·6). In the three randomised clinical trials with comparative data, no increased risk of hypersensitivity reaction (pooled RR 1·08; 95% CI 0·19-6·15), grade 3 or 4 events (0·79 [0·44-1·42]), or death (1·72 [0·77-3·82]) was noted for abacavir relative to non-abacavir regimens. None of the reported deaths were related to abacavir.

INTERPRETATION

Abacavir-related toxicity occurs early after ART initiation and is manageable. Abacavir can be safely used for first-line or second-line antiretroviral regimens in children and adolescents, especially in sub-Saharan Africa were HLA B5701 genotype is rare.

FUNDING

WHO.

HLA-B*13:01 is associated with salazosulfapyridine-induced drug rash with eosinophilia and systemic symptoms in Chinese Han population

AIM

Salazosulfapyridine (SASP) frequently causes several adverse reactions, such as drug rash with eosinophilia and systemic symptoms (DRESS). This study aims to assess whether there is an association between SASP-induced DRESS and HLA-A, -B and -C alleles in the Chinese Han population.

SUBJECTS & METHODS

We performed an association study of six subjects with SASP-induced DRESS, 30 SASP-tolerant patients and 283 general subjects from the human MHC database, all of whom are Han Chinese.

RESULTS

The frequency of the SASP-induced DRESS patients carrying the HLA-B*13:01 allele is 66.67% (4/6). It is significantly higher compared with the general Chinese Han population (15.19%, 43/283; odds ratio: 11.16; p = 0.007) or with the SASP-tolerant patients (13.33%, 4/30; odds ratio: 13.00; p = 0.004).

CONCLUSION

These findings show for the first time that in the Chinese Han population, HLA-B*13:01 is associated with SASP-induced DRESS. HLA-B*13:01 might serve as a potential genetic marker for reducing the prevalence of SASP-induced DRESS.

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.

An effective strategy to prevent allopurinol-induced hypersensitivity by HLA typing

PURPOSE

This study was conducted to evaluate the usefulness of human leukocyte antigen (HLA) typing in preventing allopurinol-induced severe cutaneous adverse reactions (SCARs) through the application of an allopurinol tolerance induction protocol or prescription of other alternative medications in high-risk patients.

METHODS

HLA typing was performed in patients with chronic renal insufficiency who needed allopurinol. HLA-B*58:01-negative patients were prescribed the usual dose of allopurinol. For HLA-B*58:01-positive patients, administration of either allopurinol based on a 28-day tolerance induction protocol or alternative medications was initiated. Hypersensitivity reactions were surveyed for 90 days and compared with the result of a previous retrospective cohort study.

RESULTS

Among a total of 401 study subjects, no SCARs were noted in HLA-B*58:01-positive patients with application of the tolerance induction protocol (n = 30) or alternative medications (n = 16), nor were any SCARs observed in HLA-B*58:01-negative patients who started allopurinol at the usual dose (n = 355). Compared with the previous retrospective cohort study, a significant reduction in SCARs was observed in HLA-B*58:01-positive patients (0 vs. 18%; P = 0.002).

CONCLUSION

This study shows the usefulness of HLA-B*58:01 screening in identifying patients at high risk for the development of allopurinol-induced SCARs and suggests that application of a tolerance induction protocol or alternative medications could be an effective strategy to prevent allopurinol-induced SCARs in HLA-B*58:01-positive patients.

Human leukocyte antigen genetic risk factors of drug-induced liver toxicology

INTRODUCTION

Drug-induced liver injury (DILI) is a rare adverse drug reaction, which impacts significantly on patients. Human leukocyte antigen (HLA) risk alleles have been found to be associated with DILI supporting an immunological basis to DILI pathogenesis.

AREAS COVERED

HLA alleles associated with risk of liver injury induced by specific therapeutic drugs are described. The evidence for a role of the adaptive immune system in DILI is presented; case-control studies showing an association between DILI and HLA alleles are reviewed. Clinical applications of pharmacogenomics are considered.

EXPERT OPINION

Increasing evidence points to a crucial role for the adaptive immune system in the pathogenesis of DILI. Identification of specific HLA alleles as risk factors through large genome-wide association studies has been instrumental in this and in vitro analyses have facilitated improved understanding of the molecular mechanisms. This provides the basis for developing clinical pharmacogenomic applications. Already, genotyping for hypersensitivity HLA risk alleles has been implemented and opportunities for pre-prescription testing in DILI identified. However, although associations are strong, the rarity of DILI means routine testing has not been formally evaluated. Nevertheless, enhanced understanding of how HLA alleles contribute to injury risk is valuable for drug development. Translation of this research into effective pre-emption and primary prevention remains the goal.

Hypersensitivity Reaction Associated with Abacavir Therapy in an Indian HIV Patient - A Case Report

The most important and unique adverse effect of abacavir (ABC) is fatal hypersensitivity reaction (HSR). The objective of this report is to describe a case of ABC induced HSR that occurred in an Indian HIV patient during treatment. Although this adverse effect is not uncommon, it is perhaps underreported or has never been reported so far in an Indian case scenario. A 44-year-old known case of HIV-1 was admitted in view of his worsening condition and very low CD4 cell counts 3 cells/μL. He was on anti-retroviral therapy since three years but not regular. On the basis of treatment failure, non-compliance and progressive low CD4 counts, the anti HIV regime was switched over to abacavir 600 mg+ atazanavir/ ritonavir 300mg/100mg Two weeks after ABC therapy he presented with maculopapular rash, headache and signs of hepatic damage (serum AST, ALP and ALT increased to 3-4 fold) suggestive of hypersensitivity reaction. As we know discontinuation of the drug is the ultimate litmus test to confirm diagnosis of drug induced adverse reaction. We did confirm ABC induced HSR by de-challenge wherein, rash disappeared within 2-3 days and LFT came back to normal within 5 days. However, no rechallenge was done. HSR was more in favour of ABC because atazanavir failed to produce any similar reaction after re-challenge.

Direct PCR: a new pharmacogenetic approach for the inexpensive testing of HLA-B*57:01

One of the most successful applications of pharmacogenetics research is the genetic screening for HLA-B*57:01, strongly associated with an increased risk to develop hypersensitivity reaction in HIV-positive patients following abacavir administration. Taking into consideration the limits of current genotyping methodologies, we have developed and validated (150 buccal swabs) an inexpensive pharmacogenetic approach for HLA-B*57:01 typing. In our assay DNA extraction and amplification are combined in one single step (direct PCR protocol), which is performed directly on the biological sample without the need of extraction and sequencing passages. The amplicons obtained by direct PCR can be easily separated on the agarose gel under ultraviolet. As per our results, the direct PCR represents a good alternative to the traditional methods of HLA-B*57:01 pharmacogenetic test, especially for those laboratories or countries where currently available approaches are often not available or not affordable. Furthermore it is an innovative approach, promoting a personalized, safer and cost-effective therapy.

Development of multiplex pyrosequencing for HLA-B*57:01 screening using single nucleotide polymorphism haplotype

WHAT IS KNOWN AND OBJECTIVE

Abacavir (ABC) is a commonly used nucleoside reverse-transcriptase inhibitor with potent antiviral activity against HIV-1. The US Food and Drug Administration and international HIV treatment guidelines recommend HLA-B*57:01 screening before initiating treatment with ABC. The current standard method for HLA-B*57:01 screening is limited by its high-cost, time-consuming and labour-intensive procedure with the requirement of a specialized laboratory. Our study aims to develop a more reliable screening test by selecting rs3093726 as an additional single nucleotide polymorphism (SNP) to combine with rs2395029 for multiplex pyrosequencing development. It offers high-accuracy, cost-effective and rapid detection.

METHODS

Multiplex pyrosequencing was developed for HLA-B*57:01 screening using rs2395029 and rs3093726 as a surrogate marker and tested in 130 Thai subjects in parallel with singleplex pyrosequencing of each SNP and the standard sequence-based method.

RESULTS AND DISCUSSION

Multiplex pyrosequencing showed 100% concordance when compared with both singleplex pyrosequencing and standard sequence-based method. This method showed 100% of negative predictive value (NPV), positive predictive value (PPV), specificity and sensitivity.

WHAT IS NEW AND CONCLUSION

Multiplex pyrosequencing is a powerful tool for HLA-B*57:01 screening using the rs2395029 and rs3093726 haplotype genotyping as surrogate marker for this HLA-B. The assay provides accurate, cost-effective and rapid detection of this haplotype. It can be applied for ABC hypersensitivity screening of the Thai population before initiating treatment with ABC.

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.