Association of HLA-B*5801 allele and allopurinol-induced Stevens Johnson syndrome and toxic epidermal necrolysis: a systematic review and meta-analysis

Insights into pharmacogenetics, drug-gene interactions, and drug-drug-gene interactions

This review explores genetic contributors to drug interactions, known as drug-gene and drug-drug-gene interactions (DGI and DDGI, respectively). This article is part of a mini-review issue led by the International Society for the Study of Xenobiotics (ISSX) New Investigators Group. Pharmacogenetics (PGx) is the study of the impact of genetic variation on pharmacokinetics (PK), pharmacodynamics (PD), and adverse drug reactions. Genetic variation in pharmacogenes, including drug metabolizing enzymes and drug transporters, is common and can increase the risk of adverse drug events or contribute to reduced efficacy. In this review, we summarize clinically actionable genetic variants, and touch on methodologies such as genotyping patient DNA to identify genetic variation in targeted genes, and deep mutational scanning as a high-throughput in vitro approach to study the impact of genetic variation on protein function and/or expression in vitro. We highlight the utility of physiologically based pharmacokinetic (PBPK) models to integrate genetic and chemical inhibitor and inducer data for more accurate human PK simulations. Additionally, we analyze the limitations of historical ethnic descriptors in pharmacogenomics research. Altogether, the work herein underscores the importance of identifying and understanding complex DGI and DDGIs with the intention to provide better treatment outcomes for patients. We also highlight current barriers to wide-scale implementation of PGx-guided dosing as standard or care in clinical settings.

Allopurinol: Clinical Considerations in the Development and Treatment of Stevens-Johnson Syndrome, Toxic Epidermal Necrolysis, and Other Associated Drug Reactions

Allopurinol lowers urate production through the inhibition of xanthine oxidase. It is oxidatively hydroxylated to oxypurinol and is the most prescribed medication for gout treatment. Although it has a beneficial effect in the treatment of this common disease, like many medications, it is also known for having numerous adverse effects. Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), diseases that exist on a spectrum, are two of the most dangerous adverse effects associated with allopurinol use. These immune-mediated disease processes involve almost every organ system. They are essential to recognize as early as possible, as they could potentially be deadly, requiring cessation of the medication with initial signs of rash or other early manifestations of SJS/TEN. One major consideration in the increased risk of allopurinol-mediated or modulated SJS/TEN is the need to have a lower dose in the setting of renal disease. The purpose of this review is not only to examine the involvement of allopurinol in SJS/TEN but also to provide detailed information about the drug, allopurinol, and general features and characteristics of SJS/TEN and other associated drug reactions.

HLA variants and their association with IgE-Mediated banana allergy: A cross-sectional study

Background

Banana allergy is on the rise in tropical regions. Advances in genomics and candidate gene identification have increased interest in genetic factors in food allergies. However, the genetic basis of IgE-mediated banana allergy is underexplored.

Objective

To characterize HLA variants and their association with IgE-mediated banana allergy.

Methods

This cross-sectional study recruited banana-allergic adults, confirmed by allergology tests, with non-allergic individuals as controls. Genomic DNA extraction and sequencing BAM files for HLA typing were conducted. Allele frequency was calculated using the direct counting method, and odds ratio (OR) with 95 % confidence interval (CI) were determined. Fisher's exact or chi-square tests were used to assess associations with Bonferroni's correction for multiple tests. The allele frequency of the Thai population from The Allele Frequency Net Database was used to compute the allele enrichment ratio (ER).

Results

A total of 59 cases and 64 controls were recruited. HLA genotyping indicated potential associations of HLA-B*15:25 (OR 11.872; p-value 0.027), HLA-C*04:03 (OR 7.636; p-value 0.033), and HLA-DQB1*06:09 (OR 11.558; p-value 0.039) with banana allergy. However, after Bonferroni correction, none of these associations reached statistical significance. Comparing allele frequency with the general population from The Allele Frequency Net Database, our ER analysis revealed a higher prevalence in the banana allergy group for B*15:25 (ER 1.849), C*04:03 (ER 1.332), and DQB1*06:09 (ER 6.602) alleles.

Conclusions

This study provides initial genetic insights into banana allergy, suggesting potential links with specific HLA alleles. Despite 12 initially identifying alleles, none were statistically significant after multiple testing correction. Larger studies are needed to detect possible significant correlations.

Molecular Docking Analysis of Four Drugs (Phenytoin, Amoxicillin, Aceclofenac and Ciprofloxacin) and Their Association With Four Human Leukocyte Antigen (HLA) Alleles

Background Numerous reports have shown the role of human leukocyte antigen (HLA) alleles in the induction of cutaneous adverse drug reactions by moderating drug metabolism. We therefore aimed to investigate the docking patterns of four HLA alleles (HLA-B x 5101, HLA-B x 1501, HLA-A x 02:06 and HLA-B x 57:01) against four commercial drugs. Methodology   Four drugs (phenytoin (PHT), amoxicillin (AMX), aceclofenac (ACE) and ciprofloxacin (CIP)) were investigated for their docking behavior against four HLA alleles (HLA-B x 5101, HLA-B x 1501, HLA-A x 02:06, and HLA-B x 57:01) using the SwissDock method. In addition, toxicity (Tox) and the search tool for interactions of chemicals (STITCH) (protein-drug interaction) analyses were also carried out using the predicating the small molecule pharmaco-kinetic (pk) properties using graph-based signature method (pkCSM) and STITCH free online servers, respectively. Results Toxicity analysis showed that two drugs (amoxicillin and ciprofloxacin) exhibit hepatotoxicity. The STITCH analysis of the drug amoxicillin revealed its interaction with two human proteins. The drug phenytoin exhibited the lowest binding energy (LBE) with all four HLA alleles (HLA-B x 5101, HLA-B x 1501, HLA-A x 02:06, and HLA-B x 57:01). Conclusions The present findings provide new knowledge about the four drugs (phenytoin (PHT), amoxicillin (AMX), aceclofenac (ACE) and ciprofloxacin (CIP)) and their binding affinities with HLA alleles, which may cause cutaneous adverse drug reactions.

Implementing HLA-B*58:01 testing prior to allopurinol initiation in Malaysian primary care setting: A qualitative study from doctors' and patients' perspective

INTRODUCTION

Allopurinol, the first-line treatment for chronic gout, is a common causative drug for severe cutaneous adverse reactions (SCAR). HLA-B*58:01 allele was strongly associated with allopurinol-induced SCAR in Asian countries such as Taiwan, Japan, Thailand and Malaysia. HLA-B*58:01 screening before allopurinol initiation is conditionally recommended in the Southeast-Asian population, but the uptake of this screening is slow in primary care settings, including Malaysia. This study aimed to explore the views and experiences of primary care doctors and patients with gout on implementing HLA-B*58:01 testing in Malaysia as part of a more extensive study exploring the feasibility of implementing it routinely.

METHODS

This qualitative study used in-depth interviews and focus group discussions to obtain information from patients with gout under follow-up in primary care and doctors who cared for them. Patients and doctors shared their gout management experiences and views on implementing HLA-B*58:01 screening in primary care. Data were coded and analysed using thematic analysis.

RESULTS

18 patients and 18 doctors from three different healthcare settings (university hospital, public health clinics, private general practitioner clinics) participated. The acceptability to HLA-B*58:01 screening was good among the doctors and patients. We discovered inadequate disclosure of severe side effects of allopurinol by doctors due to concerns about medication refusal by patients, which could potentially be improved by introducing HLA-B*58:01 testing. Barriers to implementation included out-of-pocket costs for patients, the cost-effectiveness of this implementation, lack of established alternative treatment pathway besides allopurinol, counselling burden and concern about genetic data security. Our participants preferred targeted screening for high-risk populations instead of universal screening.

CONCLUSION

Implementing HLA-B*58:01 testing in primary care is potentially feasible if a cost-effective, targeted screening policy on high-risk groups can be developed. A clear treatment pathway for patients who test positive should be made available.

Allopurinol-Induced Toxic Epidermal Necrolysis

Toxic epidermal necrolysis (TEN) is a rare and life-threatening cutaneous disease, frequently triggered by drugs. Allopurinol is one of the most frequent drugs associated with TEN, which implies detachment of a significant amount of the body surface area (BSA) and has a high morbidity and mortality associated with it. We present the case of a 68-year-old female with a recent diagnosis of hyperuricemia who started treatment with allopurinol. A week later, she presented to the emergency department with an extensive maculopapular exanthema with blisters and skin detachment. After the exclusion of other etiologies, the diagnosis of allopurinol-induced TEN was made, with 35% of BSA involvement. Due to the severity of the clinical condition, she was admitted to intensive care and treated with corticoids that had no response. So, she was started on immunoglobulins and transferred to a burn unit. She developed sepsis with multiorgan failure and required supportive treatment. She was discharged after a month, and physical rehabilitation was needed. This clinical case highlights the severity of allopurinol hypersensitivity that may happen and the importance of an accurate diagnosis and treatment for this rare disease.

Genetic association of beta-lactams-induced hypersensitivity reactions: A systematic review of genome-wide evidence and meta-analysis of candidate genes

Importance

Beta-lactams (BLs) are the most prescribed antibiotics, being the most frequent cause of drug allergy. However, the association between BL allergy and genetic variations is still unclear.

Objective

This systematic review and meta-analysis aimed to summarize the genetic effects of BL-induced hypersensitivity using existing evidence.

Methods

We searched PubMed, Medline, Scopus, EMBASE, CINAHL, and Cochrane Library from inception to September 15, 2022 with no language restriction. Genetic association studies investigating genetic variant/polymorphism and risk of drug-induced hypersensitivity reactions among individuals receiving BL-antibiotics were included. We excluded studies of acute interstitial nephritis, drug-induced liver injury, serum sickness, and isolated drug fever. Data were comprehensively synthesized and quality of study were assessed using STrengthening the Reporting of Genetic Association Studies (STREGA). The record screening, extraction and quality assessment were performed by two reviewers and discussions were made to resolve discrepancies. The effects of each variant were pooled and evaluated by modified Venice criteria.

Results

A total of 9276 records were identified, and 31 studies were eligible for inclusion. Twenty-seven were candidate-gene association studies (5416 cases and 5939 controls), while the others were next-generation sequencing (NGS) or genome-wide association studies (GWASs) (119 838 cases and 1 487 111 controls). Forty-nine polymorphisms were identified and most of them located in allergic reaction pathways. Meta-analyses of 15 candidate variants in a mixture of both immediate and non-immediate reactions revealed weak genetic effects of rs1801275 (8 studies; n = 1,560; odd ratio 0.73; 95%CI: 0.57-0.93) and rs20541 (4 studies; n = 1,482; odd ratio 1.34; 95%CI: 1.07-1.68) in IL4R and IL13, respectively. Results from GWASs and NGS identified, and confirmed associations in HLA regions including HLA-DRA, HLA-B, HLA-DQA, HLA-DRB1, and HLA-DRB3.

Conclusion

Our study summarized genetic evidence influencing BL-induced hypersensitivity and estimated effects of potential variants. We postulated that the genomic studies provide better insights to the mechanism of reactions and suggest potential effects of HLA Class II variants. However, results were inconsistent and unable to generalize in different settings. Further high-throughput studies with a well-defined function, epigenetic interaction, incorporated with clinical factors, would be beneficial for risk identification in BL-induced hypersensitivity.

Cost-effectiveness of HLA-B*58:01 testing to prevent Stevens-Johnson syndrome/toxic epidermal necrolysis in Vietnam

Background: HLA-B*58:01 is strongly associated with allopurinol-induced Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) in Vietnam. This study assessed the cost-effectiveness of this testing to prevent SJS/TEN. Methods: A model was developed to compare three strategies: no screening, use allopurinol; HLA-B*58:01 screening; and no screening, use probenecid. A willingness-to-pay of three-times gross domestic product per capita was used. Results: Compared with 'no screening, use allopurinol', 'screening' increased quality-adjusted life-years by 0.0069 with the incremental cost of Vietnam dong (VND) 14,283,633 (US$617), yielding an incremental cost-effectiveness ratio of VND 2,070,459,122 (US$89,398) per quality-adjusted life-year. Therefore, 'screening' was unlikely to be cost-effective under the current willingness-to-pay. Testing's cost-effectiveness may change with targeted high-risk patients, reimbursed febuxostat or lower probenecid prices. Conclusion: The implementation of nationwide HLAB*58:01 testing before the use of allopurinol is not cost-effective, according to this analysis. This may be due to the lack of quality data on the effectiveness of testing and costing data in the Vietnamese population.

TFOS Lifestyle: Impact of elective medications and procedures on the ocular surface

The word "elective" refers to medications and procedures undertaken by choice or with a lower grade of prioritization. Patients usually use elective medications or undergo elective procedures to treat pathologic conditions or for cosmetic enhancement, impacting their lifestyle positively and, thus, improving their quality of life. However, those interventions can affect the homeostasis of the tear film and ocular surface. Consequently, they generate signs and symptoms that could impair the patient's quality of life. This report describes the impact of elective topical and systemic medications and procedures on the ocular surface and the underlying mechanisms. Moreover, elective procedures performed for ocular diseases, cosmetic enhancement, and non-ophthalmic interventions, such as radiotherapy and bariatric surgery, are discussed. The report also evaluates significant anatomical and biological consequences of non-urgent interventions to the ocular surface, such as neuropathic and neurotrophic keratopathies. Besides that, it provides an overview of the prophylaxis and management of pathological conditions resulting from the studied interventions and suggests areas for future research. The report also contains a systematic review investigating the quality of life among people who have undergone small incision lenticule extraction (SMILE). Overall, SMILE refractive surgery seems to cause more vision disturbances than LASIK in the first month post-surgery, but less dry eye symptoms in long-term follow up.

A Drug-Drug Interaction Study of a Novel Selective Urate Reabsorption Inhibitor, SHR4640, and Xanthine Oxidase Inhibitor, Febuxostat, in Patients With Primary Hyperuricemia

SHR4640 is a novel, selective urate reabsorption inhibitor. As the mode of action of SHR4640 differs from that of a xanthine oxidase inhibitor, such as febuxostat, coadministration of these drugs may be a treatment option for patients with primary hyperuricemia. We assessed the potential drug-drug interaction between SHR4640 and febuxostat. In this single-center, open-label, randomized, drug-drug interaction study, subjects received 80 mg febuxostat or 10 mg SHR4640 alone daily in the first week, whereas during the second week a combination of SHR4640 and febuxostat was administered daily to all subjects. Plasma concentrations of SHR4640 and febuxostat were analyzed. We compared their pharmacokinetic and pharmacodynamic parameters and assessed both safety and tolerability. Compared with febuxostat alone, the geometric mean ratios (90%CIs) of the maximum concentration (C_max ) and the area under the plasma concentration-time curve over the dosing interval τ (AUC_0-τ ) for febuxostat after coadministration were 1.284 (1.016 to 1.621) and 0.984 (0.876 to 1.106), respectively. The geometric mean ratios (90%CIs) of C_max and AUC_0-τ for SHR4640 after coadministration compared with SHR4640 alone were 0.910 (0.839 to 0.988) and 0.929 (0.893 to 0.966), respectively. Febuxostat had no effect on SHR4640 pharmacokinetic parameters, as the 90%CIs of the geometric mean ratios were all within the range of 0.80 to 1.25. The coadministration of febuxostat and SHR4640 was well tolerated. The coadministration of SHR4640 with febuxostat was not associated with any clinically relevant pharmacokinetic drug interactions. SHR4640 combined with febuxostat had a synergistic effect on reducing uric acid in the pharmacodynamics, with the AUC decreasing from 7440 to 3170 h μmol/L compared with febuxostat alone and from 5730 to 2960 h μmol/L compared with SHR4640 alone.

Annular drug eruptions

Cutaneous adverse drug reactions are undesirable cutaneous changes caused by medications. Drug eruptions can mimic a wide range of dermatoses that include exanthematous (morbilliform), urticarial, pustular, bullous, papulosquamous, or granulomatous lesions, and sometimes these eruptions may present with annular, polycyclic, or polymorphous configurations. The correct identification of a cutaneous drug eruption depends on a high index of suspicion, detailed medication exposure history, chronologic evaluation of the causal relationships between drug exposures and eruptions, and the exclusion of other infectious or idiopathic diseases. Most drug eruptions are annoying but self-limited, usually resolving after the withdrawal of the causative agents. Rarely, patients have severe cutaneous adverse reactions, such as Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reaction with eosinophilia and systemic symptoms (DRESS), which are potentially lethal adverse drug reactions that involve the skin and mucous membranes and may also damage internal organs. Prompt recognition of the alarming signs of severe cutaneous adverse reactions and providing adequate treatment may thus be life-saving. We present the main clinical presentations, histopathology, possible implicated medications, and treatment of cutaneous adverse drug reactions that can present in annular configurations.

Allopurinol-Induced Stevens–Johnson Syndrome in Javanese Men With Positive HLA‐B*58:01

Background: Allopurinol is the most commonly used drug for the treatment of gout arthritis. However, the use of allopurinol is associated with severe cutaneous adverse reactions (SCARs) and life-threatening immune-mediated reactions that include Stevens–Johnson syndrome (SJS). SJS induced by allopurinol is strongly linked with the presence of HLA-B*58:01 in the Asian population. Such a study has not been conducted in Indonesia. We present two cases with clinical diagnosis of SJS. These patients had Javanese ethnicity, for which evidence on the genetic predisposition of allopurinol-induced SJS/TEN had not been established. Testing for the presence of the HLA-B∗58:01 allele was positive in both cases. Our case report confirms findings from studies in Asian countries that link HLA-B*58:01 and allopurinol-induced SJS/TEN. A larger study is needed to elicit evidence that the HLA-B*58:01 allele can potentially be used as a genetic marker for allopurinol-induced SCARs among different ethnicities in Indonesia.

[HLA-B58.01 and allopurinol hypersensitivity renal vasculitis in a Chinese patient]

INTRODUCTION

Allopurinol, widely used in the treatment of hyperuricemia and gout, has been shown to cause severe cutaneous reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis, as well as systemic reactions such as DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms). The HLA-B*5801 allele is known to be a risk factor for severe cutaneous manifestations of hypersensitivity to allopurinol, mostly in Asian populations.

OBSERVATION

We report the observation of a 47-year-old Chinese patient, with no previous medical history, carrying the HLA-B*5801 allele, who developed an isolated allopurinol hypersensitivity necrotizing renal vasculitis without cutaneous manifestations.

DISCUSSION

. The identification of this allele should be proposed before prescribing allopurinol in patients originating from certain regions of Asia, and the imputability of allopurinol should be evoked in case of necrotizing renal vasculitis, even without associated cutaneous involvement.

Genetic Association of Beta-Lactams-Induced Hypersensitivity Reactions: A Protocol for Systematic Review and Meta-Analysis

Beta-lactam (BL) antibiotics are among the drugs commonly related to hypersensitivity reactions. Several candidate gene studies and genome-wide association studies have reported associations of genetic variants and hypersensitivity reactions induced by BL antibiotics. However, the results were inconclusive. This protocol details a comprehensive systematic review of genetic factors associated with BL-induced hypersensitivity. A systematic search of literature related to genetic associations of BL-induced hypersensitivity will be performed through PubMed, Medline, Scopus, EMBASE, Web of Science, CINAHL, and the Cochrane central register of Controlled Trials (CENTRAL) from their inception dates with no language restrictions. Two reviewers will independently screen, extract, and appraise the risk of bias. Frequencies of genetic variants that comply with Hardy–Weinberg equilibrium will be extracted and pooled. Genetic models will be applied to variant effect calculation as per allele and genotype analysis. Based on statistical heterogeneity among studies, common effect estimation (odds ratio) and its corresponding 95% confidence interval will be analyzed. Sensitivity and subgroup analyses will be performed to determine the robustness of eligible studies. This systematic review and meta-analysis will provide comprehensive evidence of genetic effects regarding BL-induced hypersensitivity. The findings will enlighten the determination of disease-related genotypes that would potentially reveal allergy profiling in patients.

Drug-induced Stevens-Johnson syndrome: a disproportionality analysis from the pharmacovigilance database of the World Health Organization

BACKGROUND

Stevens-Johnson syndrome is a rare but serious skin condition, which if left unattended can lead to death. Stevens-Johnson syndrome is usually attributed to drug-induced reactions, thus making it vital for clinicians to prevent its occurrence by knowing the trigger drugs. The objective of this study was to comprehensively and systematically excavate the drugs that cause SJS to provide references for clinicians to use drugs safely.

RESEARCH DESIGN AND METHODS

This is an observational, retrospective study, conducting a disproportionality analysis. Where the Information Component (IC) method and Reporting odds ratio (ROR) are used to mine the drugs that cause SJS.

RESULTS

A total of 17,787,905 reports were extracted from VigiBase database, of which 25,051 reports were related to SJS. The 18-44 age group had the largest number of cases (N=7,973, 31.83%). A total of 295 drugs was detected as signals. Allopurinol (IC025/ROR025=5.86/69.84), phenytoin (IC025/ROR025=5.60/57.65) and carbamazepine (IC025/ROR025=5.25/43.88) were the top 3 strongest signals. Our study only considered the possibility of SJS caused by a single drug.

CONCLUSIONS

Carbamazepine and allopurinol were two strongest signals in different age groups and gender groups. Garenoxaci, carbocisteine and dimetindene were strong signals, but there are no relevant cases reported on PubMed or specific SJS in labels, which need further study to verify.

Fixed drug eruption in a patient of HLA-B*58:01 negative after allopurinol administration: A case report

WHAT IS KNOWN AND OBJECTIVE

Allopurinol is widely used for hyperuricemia and gouty arthritis, but is associated with cutaneous adverse drug reactions (CADRs). HLA-B*58:01 is a highly specific and effective genetic marker for the detection of allopurinol-induced CADRs, especially for Asian descents.

CASE SUMMARY

A 60-year-old Chinese Han male patient took allopurinol for lowering uric acid after the negative result from HLA-B*58:01 testing. Then, he experienced episodes of well-demarcated pruritic erythematous patches on the whole body that developed into blisters and pustular eruption. Fixed drug eruption (FDE) was diagnosed by skin biopsy and improved with withdrawal and hormone treatments.

WHAT IS NEW AND CONCLUSION

It should be kept in mind that cutaneous drug eruption might occur after allopurinol administration in Asians of HLA-B*58:01 negative. Awareness among medical practitioners about FDE can lead to correct diagnosis, treatment and decreased damage as well as lower therapeutic costs.

Low-Dose Azathioprine in Combination with Allopurinol: The Past, Present and Future of This Useful Duo

The inflammatory bowel diseases (IBD) are complex immune-mediated inflammatory diseases that are associated with significant morbidity around the world. As our understanding of IBD, and other immune-mediated inflammatory diseases, advances the number of therapeutic targets has increased which has rapidly driven the development and introduction of new therapies. While these new therapies have shown promise they come with the significant drawback of high costs. For many IBD patients around the world the cost of newer therapies is prohibitive which means treating clinicians often need to turn to optimising simpler, older, and inexpensive medications. The concept of optimising well established cheaper medications is not unique to the management of IBD as health systems all over the world look to reduce costs while simultaneously improving patient outcomes. Despite thiopurines being used in the management IBD for over 60 years, many clinicians are still hesitant to use them due to perceptions around limited efficacy and poor tolerance. One method identified to potentially increase utilisation of thiopurines involves the coadministration of allopurinol. In this review we will explore the history, pharmacology, recent studies and give recommendations for the utilisation of the usual duo of azathioprine combined with allopurinol.

Biases associated with epidermal necrolysis reporting in pharmacovigilance: An exploratory analysis using World Health Organization VigiBase

BACKGROUND

Possible biases in pharmacovigilance reporting may impact epidermal necrolysis (EN) and drugs associations.

OBJECTIVES

To assess biases associated with EN-reporting.

METHODS

Using VigiBase, the World Health Organization-pharmacovigilance database, among drugs associated with EN between 2016 and 2020, we used an unsupervised clustering including reports characteristics, that is, reporter quality, time from drug intake to EN onset, and only one suspected drug in the report.

RESULTS

Among 152 drugs, three clusters were identified. Cluster 1 (n = 41) exhibited drugs frequently reported within a time from intake to onset longer than 4 days, in 57 ± 13% of reports. It corresponded to well-reported drugs and was composed mainly of antivirals and antiepileptics. Cluster 2 (n = 42) exhibited drugs frequently reported within a time from drug intake to onset shorter than 4 days, in 31 ± 12% of reports. It corresponded to drugs with a high risk of protopathic bias and was composed of nonsteroidal anti-inflammatory drugs (NSAIDs), analgesics, and antibiotics. Cluster 3 (n = 69) exhibited drugs frequently reported with an unavailable time from drug intake to reaction, in 66 ± 11% of reports, and reported by a high frequency of consumers (9 ± 9%). It corresponded to drugs reported with a high risk of classification bias, and was composed of anticancer therapies and cardiovascular drugs.

CONCLUSION

Protopathic and classification biases impact EN-reporting and should be considered regarding associations with antibiotics, NSAIDs, analgesics, anticancer therapies, and cardiovascular drugs.

Clinical Utility of HLA-B*58:01 Genotyping to Prevent Allopurinol-Induced SJS/TEN

Purpose: A 28-year-old male reported to our hospital with Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) overlap syndrome that developed as an adverse drug reaction (ADR) to allopurinol. HLA-B*58:01 allele is associated with an increased risk of developing allopurinol-induced SJS/TEN. Methods: Genomic DNA was extracted from peripheral blood leukocytes. DNA sequencing was done using SANGER sequencing method. Results: Pharmacogenetic testing results revealed positive for HLA-B*58:01 allele. Symptoms of the patient receded after allopurinol withdrawal. Conclusion: The thrust of personalized therapy is from decoding the individual specific genetic variations astutely for better therapeutic outcomes such as reducing the ADRs. Pharmacogenetic testing is emerging as a safe, fast, and economic screening tool for personalized therapy by preventing ADRs. Pharmacogenetic HLA-B*58:01 allele testing before allopurinol administration could significantly reduce the incidence of SJS/TEN and associated mortalities/morbidities and thereby represent a potential cost-effective intervention.

Toxic Epidermal Necrolysis Caused by Allopurinol: A Serious but Still Underestimated Adverse Reaction

Patient: Female, 75-year-old

Final Diagnosis: Toxic epidermal necrolysis

Symptoms: Exanthema • rash • shivers • weakness

Medication: —

Clinical Procedure: Analgesia • ciclosporine • corticosteroids • topical and systemic treatment

Specialty: Critical Care Medicine • Dermatology

Allopurinol hepatotoxicity is associated with human leukocyte antigen Class I alleles

BACKGROUND/AIMS

Allopurinol can cause HLA class I-associated life-threatening severe skin reactions. However, HLA risk and association with clinical features in allopurinol hepatotoxicity are unknown.

METHODS

Eleven of 17 patients with suspected allopurinol hepatotoxicity enrolled into the Drug-Induced Liver Injury Network were adjudicated as definite, highly likely, or probable. High-resolution HLA sequencing was undertaken in cases and compared with population and other DILI controls.

RESULT

Median age was 60 years, 54% were male, and 63% African- American, 27% Caucasian, and 9% Hispanic. Patients presented at a median of 52 days after starting allopurinol, all were hospitalized and six were jaundiced. The median peak ALT, alkaline phosphatase, and total bilirubin were 525 U/L, 521 U/L, and 7.8 mg/dl, respectively, with a median R ratio of 2.7 at onset. During follow-up, nine patients were treated with corticosteroids including five of the six with suspected DRESS. Three patients died including two from liver failure at 38 and 45 days after onset, and the remaining eight recovered. Three HLA alleles were found to be overrepresented in allopurinol cases, particularly in African Americans: HLA-B*58:01, which has been previously linked to severe skin reactions, and HLA-B*53:01 and HLA-A*34:02, all of which are more frequently found in African Americans than European Americans or Latinos.

CONCLUSIONS

Allopurinol hepatotoxicity is associated with systemic hypersensitivity, a short latency to onset, African-American race and three HLA risk alleles, HLA-B*58:01, HLA-B*53:01, and HLA-A*34:02-58:01 testing may help confirm a diagnosis of hepatotoxicity in allopurinol-treated patients.

HLA-B*58:01 screening to prevent allopurinol-induced severe cutaneous adverse reactions in Chinese patients with chronic kidney disease

Human leukocyte antigen (HLA)-B*58:01 allele is a significant risk factor for allopurinol-induced severe cutaneous adverse reactions (SCARs) which is potentially fatal. In some studies, chronic kidney disease (CKD) was also implicated to compound the risk of SCARs. We aim to investigate if pre-treatment HLA-B*58:01 screening can prevent allopurinol-induced SCARs in Chinese patients with CKD and its cost-effectiveness. We prospectively recruited Chinese CKD patients who required allopurinol during 2011-2015 and performed pre-treatment HLA testing (HLA screening group). Patients tested positive for HLA-B*58:01 were refrained from allopurinol while those tested negative were prescribed allopurinol. The incidence of SCARs in the HLA screening group was compared with the historical control in previous 5 years and the cost-effectiveness of HLA testing was analyzed. In the historical control (2006-2010), 3605 patients on allopurinol were screened, 22 out of 1027 (2.14%) CKD Chinese patients newly started on allopurinol developed SCARs, including 6 SJS/TEN. In the HLA screening group, 28 out of 192 patients (14.6%) tested HLA-B*58:01 positive were advised to avoid allopurinol; 156 out of 164 HLA-B*58:01-negative patients received allopurinol and none developed SCARs. The incidence rate of SCARs was significantly lower in the HLA screening group compared with controls (0% vs 2.14% respectively, p = 0.037*). The targeted HLA screening approach was associated with lower healthcare costs compared with no HLA screening (US$ 92,430 vs US$ 281,226). Pre-treatment HLA-B*58:01 screening is cost-effective to target on patients with CKD in Chinese to prevent allopurinol-induced SCARs.

Therapeutic approaches in the treatment of gout

Gout is a disease in which the metabolic condition hyperuricemia leads to the formation of monosodium urate crystals, which provoke acute and chronic inflammatory responses through activation of the innate immune system. Recent advances in our knowledge of gout pathogenesis have emphasized the role of the kidneys in urate handling, the evolutionary loss of uricase as a necessary precondition for hyperuricemia, and the central role of IL-1ß in the pathogenesis of gouty inflammation. These, and other advances, have shaped our current strategies for managing gout. Here, we review the most current, evidence-based gout management approaches, including treating acute flares, addressing gout through the long-term regulation of serum urate, and prophylaxis against gouty flares during urate lowering.

Prevalence and Causes of Hyperuricemia in Children

Introduction  There are various factors responsible for hyperuricemia in children, however, there is extremely limited local data available. In this study, we aim to determine the causes and risk factors associated with hyperuricemia. This study will assist pediatric consultants to identify children who might be at risk of hyperuricemia and manage them accordingly. Methods This study was conducted in pediatric outpatient departments of various tertiary care hospitals from January 2018 to December 2019. Five thousand (n = 5000) children of either gender between the age group of 1-14 years, were enrolled in the study after informed consent from their parents. Uric acid levels were assessed by using the UASure blood uric acid monitoring handheld device. Results  In our study, n = 1301 (26.02%) children had hyperuricemia. Hyperuricemia was more common in male compared to females (65.49% vs. 34.51%; p-value <0.00001) and in older children (9 ± 2 years vs. 7 ± 3; p-value <0.00001). In hyperuricemia patients, the most common disorder was gastroenteritis (23.98%), followed by respiratory infection (23.14%) and asthma (15.45%). Conclusion  Hyperuricemia in children is very prevalent in the local setting. Patients with pre-existing conditions like congenital heart disease, asthma, epilepsy, and cancers should routinely be screened for hyperuricemia and managed accordingly to avoid long-term complications associated with hyperuricemia.

Genetic Markers for Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis in the Asian Indian Population: Implications on Prevention

This review attempts to collate all the studies performed in India or comprising a population originating from India and to find out if there is an association between the HLA (human leucocyte antigen) type of individual and development of Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) subsequent to medication use. The authors performed a PubMed search of all articles published in English from 2009 to 2019 for articles that studied HLA type in patients who developed SJS/TEN after intake of a specific drug in the Asian Indian population or in individuals of Asian Indian origin. The selection criteria were satisfied by a total of 11 studies that reported HLA associations with specific drugs, which induced SJS/TEN, mainly anti-epileptic drugs, and cold medicine/non-steroidal anti-inflammatory drugs. These studies involved a small number of patients, and hence, there is limited evidence to conclude if these associations can be extrapolated to a larger population of the same ethnicity. Similar multi-center studies need to be conducted with a larger sample size to confirm these associations. This would have implications in policy making and for understanding the potential of using genetic markers as a screening tool before prescribing a drug to a patient, which might make them susceptible to developing a potentially life-threatening disease such as SJS/TEN. This is possibly the only mode of primary prevention for this potentially fatal severe cutaneous adverse drug reaction.

HLA-B*1502 is associated with aromatic anticonvulsant drug-induced cutaneous adverse drug reactions among the Hakka population in China

Background

The purpose of this study was to analyze the correlation between aromatic antiepileptic drug-induced cutaneous adverse drug reactions and HLA-B*1502 genotype in patients from the Hakka population in Meizhou.

Methods

A total of 214 epileptic patients taking aromatic (n = 94) or non-aromatic anticonvulsants (n = 120) were included in the study from September 2016 to May 2018. Clinical data for the patients were analyzed retrospectively and HLA-B*1502 genotype testing was carried out.

Results

Thirty patients were HLA-B*1502(+) (14.02%). The proportion of HLA-B*1502(−) genotype and incidence of adverse drug reactions (ADRs) differed significantly between the two drug groups. In the aromatic anticonvulsant group, maculopapular eruption (MPE), Stevens–Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and hypersensitivity syndrome (HSS) occurred in 10 patients, including eight HLA-B*1502(+) and two HLA-B*1502(−) patients. MPE, HSS, SJS, and TEN occurred in 26 patients in the non-aromatic anticonvulsant group, including one HLA-B*1502(+) and 25 HLA-B*1502(−) patients. There was a significant correlation between the proportions of HLA-B*1502(+) genotype and induced cutaneous adverse drug reactions in the two groups.

Conclusions

HLA-B*1502 is associated with aromatic anticonvulsant drug-induced cutaneous adverse drug reactions among the Hakka population in Meizhou, China.

Real-world evidence of population differences in allopurinol-related severe cutaneous adverse reactions in East Asians: A population-based cohort study

Abstract

Allopurinol‐related severe cutaneous adverse reactions (SCARs) are strongly associated with HLA‐B*58:01, the allele frequency (AF) of which is largely different among East Asians. However, evidence of population differences in SCAR development and relevance of genetic and/or other risk factors in the real‐world remain unelucidated. This study aimed to evaluate population differences in allopurinol‐related SCAR incidence related to genetic and/or other risk factors among East Asians in the real‐world. A population‐based cohort study was conducted using claims databases from Taiwan, Korea, and Japan. New users of allopurinol (311,846; 868,221; and 18,052 in Taiwan, Korea, and Japan, respectively) were followed up to 1 year. As control drugs, phenytoin and carbamazepine were used. The crude incidence rate ratios (IRRs) of SCARs for allopurinol against phenytoin or carbamazepine were the highest in Taiwan (IRR, 0.62 and 1.22; 95% confidence interval [CI], 0.54–0.72 and 1.01–1.47, respectively), followed by Korea (IRR, 0.34 and 0.82; 95% CI, 0.29–0.40 and 0.77–0.87), and the lowest in Japan (IRR, 0.04 and 0.16; 95% CI, 0.02–0.08 and 0.09–0.29). This order was accordant with that of AF ratios (AFRs) reported of HLA‐B*58:01 against alleles responsible for phenytoin‐ or carbamazepine‐related SCARs. The IRRs were higher in patients with chronic kidney disease, females, and elderly. This study demonstrated population differences in the risk of allopurinol‐related SCAR development among East Asians based on genetic and other common risk factors. This finding will help to promote appropriate risk management for allopurinol‐related SCARs based on ethnic origins.

Genetic susceptibilities and prediction modeling of carbamazepine and allopurinol-induced severe cutaneous adverse reactions in Vietnamese

Aims: To determine genetic susceptibility markers for carbamazepine (CBZ) and allopurinol-induced severe cutaneous adverse reactions (SCARs) in Vietnamese. Methods: A case-control study was performed involving 122 patients with CBZ or allopurinol-induced SCARs and 120 drug tolerant controls. Results: HLA-B*58:01 was strongly associated with allopurinol-induced SCARs and strongly correlated with SNP rs9263726. HLA-B*15:02 was associated with CBZ-induced Stevens-Johnson syndrome/toxic epidermal necrolysis but not with drug-induced hypersensitivity syndrome/drug rash with eosinophilia and systemic symptoms. No association was found between HLA-A*31:01 and CBZ-induced SCARs. HLA-B*58:01 and rs3909184 allele A with renal insufficiency were shown to increase the risk of allopurinol-induced SCARs. Conclusion: HLA-B*58:01 and HLA-B*15:02 confer susceptibility to allopurinol-induced SCARs and CBZ-induced SJS/TEN in Vietnamese. SNP rs9263726 can be used as a surrogate marker in identifying HLA-B*58:01.

Risk factors for cutaneous reactions to allopurinol in Kinh Vietnamese: results from a case-control study

OBJECTIVE

The aim of this study was to investigate risk factors for cutaneous adverse reactions (CARs) in Kinh Vietnamese.

METHODS

All patients were prospectively recruited in Ho Chi Minh City. Presence of the HLA-B*58:01 allele was determined by real-time PCR-sequence-specific amplification by using the PG5801 Detection Kit (Pharmigene, Taipei). Patients with severe (SCARs) and mild (MCARs) CARs and controls were compared for differences in features prospectively collected, and odds ratios (ORs) with 95% confidence intervals (CIs) were estimated.

RESULTS

On comparing 32 patients with SCARs and 395 tolerant controls, we identified eight strong risk factors: increased age (OR 15.1 [95% CI 5.8-40.1], P < 0.0001), female sex (OR 333 [40-43,453], P < 0.0001), allopurinol for asymptomatic hyperuricemia (OR 955 [120-125,847], P < 0.0001), allopurinol starting dose > 150 mg (OR 316 [101-122], P < 0.0001), diuretics intake (OR 304 [35-40,018], P < 0.0001), eGFR < 60 ml/min/1.73 m² (OR 100 [32-353], P < 0.0001), history of allopurinol-induced skin reaction (OR 78 [6-10,808], P = 0.004), and HLA-B*58:01 carriage (OR 147 [45-746], P < 0.0001). HLA-B*58:01 allele frequency in controls was 7.3%. For MCARs (n = 74), risk factors were eGFR < 60 ml/min/1.73 m² (OR 4.9 [1.61-14.6], P = 0.006), history of allopurinol-induced skin reaction (OR 27 [2-3777], P = 0.01), and asymptomatic hyperuricemia (OR 27 [2-3777], P = 0.01).

CONCLUSION

This study confirmed 8 risk factors, including HLA-B*58:01, for SCARs and identified 3 risk factors for MCARs in Kinh Vietnamese. HLA-B*58:01 genotyping could guide the indication for allopurinol in Kinh Vietnamese patients with gout.

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.

Oral Mucosal Injury Caused by Targeted Cancer Therapies

Targeted cancer therapies have fundamentally transformed the treatment of many types of cancers over the past decade, including breast, colorectal, lung, and pancreatic cancers, as well as lymphoma, leukemia, and multiple myeloma. The unique mechanisms of action of these agents have resulted in many patients experiencing enhanced tumor response together with a reduced adverse event profile as well. Toxicities do continue to occur, however, and in selected cases can be clinically challenging to manage. Of particular importance in the context of this monograph is that the pathobiology for oral mucosal lesions caused by targeted cancer therapies has only been preliminarily investigated. There is distinct need for novel basic, translational, and clinical research strategies to enhance design of preventive and therapeutic approaches for patients at risk for development of these lesions. The research modeling can be conceptually enhanced by extrapolating "lessons learned" from selected oral mucosal conditions in patients without cancer as well. This approach may permit determination of the extent to which pathobiology and clinical management are either similar to or uniquely distinct from oral mucosal lesions caused by targeted cancer therapies. Modeling associated with oral mucosal disease in non-oncology patients is thus presented in this context as well. This article addresses this emerging paradigm, with emphasis on current mechanistic modeling and clinical treatment. This approach is in turn designed to foster delineation of new research strategies, with the goal of enhancing cancer patient treatment in the future.

Heart disease and the risk of allopurinol-associated severe cutaneous adverse reactions: a general population-based cohort study

BACKGROUND

Allopurinol is commonly prescribed for gout, and its clinical use may expand with ongoing trials assessing its potential cardiorenal benefits. Because heart disease has been suggested to be a risk factor for allopurinol-associated severe cutaneous adverse reactions, we sought to confirm this association in a Canadian general population cohort.

METHODS

We used population data from British Columbia, Canada, to identify all incident allopurinol users between 1997 and 2015. We examined the association between heart disease (ischemic heart disease and heart failure) and the risk of hospital admission for severe cutaneous adverse reactions, adjusting for known and purported risk factors. We also evaluated the joint effects of combined clinical and demographic risk factors.

RESULTS

Among 130 325 allopurinol initiators, 109 hospital admissions occurred for allopurinol-associated severe cutaneous adverse reactions. The multivariable relative risk among those with heart disease was 1.55 (95% confidence interval 1.01-2.37). Patients with heart disease and chronic kidney disease who were started on an allopurinol dosage of greater than 100 mg/d had an 11-fold higher risk. Allopurinol initiation at a lower dosage among patients with heart disease and chronic kidney disease resulted in a fivefold reduction in risk. Older women with heart disease from regions with large Asian populations had a 23-fold higher risk of allopurinol-associated severe cutaneous adverse reactions than younger men without heart disease from other regions.

INTERPRETATION

Heart disease is independently associated with risk of allopurinol-associated severe cutaneous adverse reactions, similar to chronic kidney disease, and low-dosage allopurinol initiation may substantially mitigate this risk. Risk factors for these rare but serious reactions should be considered when initiating allopurinol.

HLA-B*58: 01 association in allopurinol-induced severe cutaneous adverse reactions: the implication of ethnicity and clinical phenotypes in multiethnic Malaysia

OBJECTIVE

The association between human leukocyte antigen (HLA)-B*58:01 and risk of allopurinol-induced severe cutaneous adverse reactions (AIS) was observed across different populations. We explore the association between HLA-B*58:01 and AIS risk in multiethnic Malaysian population. The HLA-B*58:01 risk for different AIS clinical phenotypes and ethnicity was determined.

METHODS

We performed a case-control association study by genotyping the HLA-B alleles of 55 patients with AIS [11 toxic epidermal necrolysis (TEN), 21 Steven Johnson syndrome (SJS) 22 drug reaction wit eosinophilia and systemic symptoms (DRESS) and one acute generalized exanthematous pustulosis (AGEP)] and 42 allopurinol-tolerant controls (ATC).

RESULTS

HLA-B*58:01 was positive in 89.1 and 14.3% of the AIS and ATC study groups [odds ratio (OR) = 49.0, 95% confidence interval (CI) = 14.6-164.4, P < 0.0001)], respectively. Our data showed that 93.8% of the AIS-SJS/TEN patients and 86.4% of the AIS-DRESS patients were HLA-B*58:01 positive (AIS-SJS/TEN, OR = 90, 95% CI = 16.9-470.1, P < 0.0001 and AIS-DRESS OR = 38, 95% CI = 8.5-169.2, P < 0.0001). Stratification by ethnicity and clinical phenotypes revealed a significant increased risk between HLA-B*58:01 and Chinese-AIS patients (OR = 137.5, 95% CI = 11.3-1680.2, P < 0.0001), in particular Chinese patients with AIS-SJS/TEN phenotype (100% HLA-B*58:01 positive). HLA-B*58:01 was positive in 90.9% Chinese AIS-DRESS (P < 0.0001). Highly significant associations of HLA-B*58:01 were observed in Malay AIS-SJS/TEN (OR = 78, 95% CI = 9.8-619.9, P < 0.0001) and Malay AIS-DRESS (OR = 54, 95% CI = 6.6-442.9, P < 0.0001). Although the number of Indian-AIS patients was relatively small (n = 2), both were HLA-B*58:01 positive.

CONCLUSION

Our data suggest strong associations between HLA-B*58:01 and AIS in Malaysian population with Chinese and Malays ethnicity. The strong association was also observed in three different clinical phenotypes of AIS, mainly the AIS-SJS/TEN.

Is HLA-B*58:01 genotyping cost effective in guiding allopurinol use in gout patients with chronic kidney disease?

Aim: Concerns for fatal severe cutaneous adverse reactions (SCARs) hamper allopurinol use. Methods and material: We adopted a health system perspective to evaluate the cost-effectiveness of HLA-B*58:01 genotyping before allopurinol initiation. A decision tree compared three treatment strategies in gout patients with chronic kidney disease who have higher risk for SCAR. They were standard allopurinol treatment followed by febuxostat in nonresponders, test-positive patients receive febuxostat while test-negative receive allopurinol and universal use of febuxostat. Results: The first strategy was the most cost effective. Genotyping dominated universal febuxostat use. Time horizon and SCAR incidence were the most influential factors on the incremental cost-effectiveness ratio. Conclusion: HLA-B*58:01 genotyping compared with standard allopurinol-febuxostat sequential treatment does not provide good value for money in gout with chronic kidney disease.

Genetic Diversity of HLA Class I and Class II Alleles in Thai Populations: Contribution to Genotype-Guided Therapeutics

Human leukocyte antigen (HLA) class I and II are known to have association with severe cutaneous adverse reactions (SCARs) when exposing to certain drug treatment. Due to genetic differences at population level, drug hypersensitivity reactions are varied, and thus common pharmacogenetics markers for one country might be different from another country, for instance, HLA-A*31:01 is associated with carbamazepine (CBZ)-induced SCARs in European and Japanese while HLA-B*15:02 is associated with CBZ-induced Stevens–Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) among Taiwanese and Southeast Asian. Such differences pose a major challenge to prevent drug hypersensitivity when pharmacogenetics cannot be ubiquitously and efficiently translated into clinic. Therefore, a population-wide study of the distribution of HLA-pharmacogenetics markers is needed. This work presents a study of Thai HLA alleles on both HLA class I and II genes from 470 unrelated Thai individuals by means of polymerase chain reaction sequence-specific oligonucleotide (PCR-SSO) in which oligonucleotide probes along the stretches of HLA-A, -B, -C, -DRB1, -DQA1, and -DQB1 genes were genotyped. These 470 individuals were selected according to their regional locations, which were from North, Northeast, South, Central, and a capital city, Bangkok. Top ranked HLA alleles in Thai population include HLA-A*11:01 (26.06%), -B*46:01 (14.04%), -C* 01:02 (17.13%), -DRB1*12:02 (15.32%), -DQA1*01:01 (24.89%), and -DQB1*05:02 (21.28%). The results revealed that the distribution of HLA-pharmacogenetics alleles from the South had more HLA-B75 family that a typical HLA-B*15:02 pharmacogenetics test for SJS/TEN screening would not cover. Besides the view across the nation, when compared HLA alleles from Thai population with HLA alleles from both European and Asian countries, the distribution landscape of HLA-associated drug hypersensitivity across many countries could be observed. Consequently, this pharmacogenetics database offers a comprehensive view of pharmacogenetics marker distribution in Thailand that could be used as a reference for other Southeast Asian countries to validate the feasibility of their future pharmacogenetics deployment.

An Update on the Immunological, Metabolic and Genetic Mechanisms in Drug Hypersensitivity Reactions

Drug hypersensitivity reactions (DHRs) represent a major burden on the healthcare system since their diagnostic and management are complex. As they can be influenced by individual genetic background, it is conceivable that the identification of variants in genes potentially involved could be used in genetic testing for the prevention of adverse effects during drug administration. Most genetic studies on severe DHRs have documented HLA alleles as risk factors and some mechanistic models support these associations, which try to shed light on the interaction between drugs and the immune system during lymphocyte presentation. In this sense, drugs are small molecules that behave as haptens, and currently three hypotheses try to explain how they interact with the immune system to induce DHRs: the hapten hypothesis, the direct pharmacological interaction of drugs with immune receptors hypothesis (p-i concept), and the altered self-peptide repertoire hypothesis. The interaction will depend on the nature of the drug and its reactivity, the metabolites generated and the specific HLA alleles. However, there is still a need of a better understanding of the different aspects related to the immunological mechanism, the drug determinants that are finally presented as well as the genetic factors for increasing the risk of suffering DHRs. Most available information on the predictive capacity of genetic testing refers to abacavir hypersensitivity and anticonvulsants-induced severe cutaneous reactions. Better understanding of the underlying mechanisms of DHRs will help us to identify the drugs likely to induce DHRs and to manage patients at risk.

The net clinical benefits of febuxostat versus allopurinol in patients with gout or asymptomatic hyperuricemia - A systematic review and meta-analysis

BACKGROUND AND AIMS

Systemic reviews and meta-analyses suggest hyperuricemia is a cardiovascular risk factor. The effects of xanthine oxidase inhibitors on cardiac outcomes remain unclear. We assessed the effects of febuxostat and allopurinol on mortality and adverse reactions in adult patients with hyperuricemia.

METHODS AND RESULTS

PubMed and EMBASE were searched to retrieve randomized controlled trials of febuxostat and allopurinol from January 2005 to July 2018. The meta-analysis consisted of 13 randomized controlled trials with a combined sample size of 13,539 patients. Febuxostat vs. allopurinol was not associated with an increased risk of cardiac-related mortality in the overall population (OR: 0.72, 95% CI: 0.24-2.13, P = 0.55). Regarding adverse skin reactions, the patients receiving febuxostat had significantly fewer adverse skin reactions than those receiving allopurinol treatment (OR: 0.50, 95% CI: 0.30-085, P = 0.01). Compared with allopurinol, febuxostat was associated with an improved safety outcome of cardiac-related mortality and adverse skin reactions (OR: 0.72, 95% CI: 0.55-0.96, P = 0.02). The net clinical outcome, composite of incident gout and the safety outcome, was not different significantly in the patients receiving febuxostat or allopurinol (OR: 1.04, 95% CI: 0.76-0.1.42, P = 0.79). In sensitivity analyses, a borderline significance was found in the patients randomized to febuxostat vs. allopurinol regarding cardiac-related mortality (OR: 1.29, 95% CI: 1.00-1.67, P = 0.05) after the CARES study was included.

CONCLUSION

Febuxostat vs. allopurinol was associated with the improved safety outcome and have comparable mortality and net clinical outcome in patients with hyperuricemia.

REGISTRATION NUMBER

PROSPERO(CRD42018091657).

HLA-DRB1*07:01 and lapatinib-induced hepatotoxicity: a systematic review and meta-analysis

Associations between HLA-DRB1*07:01 and lapatinib-induced hepatotoxicity have been reported. To consolidate the results from all available reports in scientific databases, systematic review and meta-analysis techniques were used to quantify these associations. Studies investigating associations between HLA-DRB1*07:01 and lapatinib-induced hepatotoxicity were systematically searched in PubMed, Human Genome Epidemiology Network, and the Cochrane Library. Primary outcomes were the associations between HLA-DRB1*07:01 and lapatinib-induced hepatotoxicity. Overall odds ratios (ORs) with the corresponding 95%CIs were calculated using a random-effect model to determine the associations between HLA-DRB1*07:01 and lapatinib-induced hepatotoxicity. A clear association between HLA-DRB1*07:01 and lapatinib-induced hepatotoxicity was identified in our analyses. The summary OR was 6.23 (95%CI = 4.11-9.45). Similar associations were also found in the subgroup analyses by lapatinib treatment regimens. ORs were 10.04 (95%CI = 6.15-16.39), 8.65 (95%CI = 4.52-16.58), and 3.88 (95%CI = 2.20-6.82) in the lapatinib group, lapatinib + trastuzumab group, and lapatinib + chemotherapy or lapatinib + trastuzumab + chemotherapy group, respectively. Since HLA-DRB1*07:01 is associated with lapatinib-induced hepatotoxicity, genetic screening of HLA-DRB1*07:01 in breast cancer patients prior to lapatinib therapy is warranted for patient safety. In addition, further studies should define the risk of HLA-DRB1*07:01 and lapatinib-induced hepatotoxicity in specific ethnicities.

Human leukocyte antigen-associated severe cutaneous adverse drug reactions: from bedside to bench and beyond

Despite their being uncommon, severe cutaneous adverse drug reactions (SCARs) result in a very great burden of disease. These reactions not only carry with them a high mortality (10%-50%) and high morbidity (60%) with severe ocular complications, alopecia, oral and dental complications and development of autoimmune diseases, but also create a substantial economic burden for patients' families and society. SCARs are, therefore, an important medical problem needing a solution in many countries, especially in Asia. The clinical spectrum of SCARs comprises Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS (drug rash with eosinophilia and systemic symptoms) (also known as drug hypersensitivity syndrome or drug-induced hypersensitivity syndrome) and acute generalised exanthematous pustulosis. Recent crucial advances in determining genetic susceptibility and understanding how T cells recognise certain medications or their metabolites via the major histocompatibility complex and the effects of cofactors, have led to the implementation of cost-effective screening programs enabling prevention in a number of countries, and to further understanding of the patho-mechanisms involved in SCARs and their significance. In this review, we document comprehensively the journey of SCARs from bedside to bench and outline future perspectives in SCARs research.

Clinical Usefulness of HLA-B∗58:01 Genotyping in Gouty Arthritis

Allopurinol is an effective urate lowering agent but may lead to rare but life-threatening severe cutaneous adverse reactions (SCAR). Genetic predisposition, age, sex, renal function, dosage and concomitant diuretic use are known risk factors of allopurinol related SCAR. Among these factors, HLA-B[Formula: see text]58:01 confers the highest risk. Frequency of the HLA-B[Formula: see text]58:01 allele varies significantly across different ethnic groups. Although the usefulness of HLA-5801 genotyping before initiation of allopurinol has been confirmed by clinical studies, its positive predictive value for SCAR is low because of the low prevalence of HLA-5801 in some localities. Thus, health economic analysis does not consistently show cost-effectiveness of universal screening of HLA-5801 before initiation of allopurinol. However, screening of this genotype in high-risk subjects, including those with renal impairment or advanced age, should be considered on individual basis.

Association of human leukocyte antigen variants and allopurinol-induced Stevens-Johnson syndrome and toxic epidermal necrolysis: A meta-analysis

PURPOSE

The association between human leukocyte antigen (HLA) variants and allopurinol-induced Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) was evaluated through a pooled analysis of published studies.

METHODS

A comprehensive search was performed in multiple databases, including PubMed, MEDLINE, ISI Web of Knowledge, EMBASE, Cochrane Register of Controlled Trials, and Science Direct. Studies investigating the association between HLA alleles with allopurinol-induced SJS or TEN were retrieved, and the data were independently extracted. The overall odds ratios (ORs) with corresponding 95% confidence intervals were calculated to determine the association between the presence of HLA variant in at least one allele and allopurinol-induced SJS or TEN. To test the robustness of the meta-analysis results, a sensitivity analysis was performed by removing each study one at a time and calculating the pooled ORs of the remaining studies. The fixed-effects and random-effects models were used to pool the collected data.

RESULTS

A total of 4 studies with 81 allopurinol-induced SJS or TEN cases and matched controls (allopurinol-tolerant patients) or population controls (general population) were identified. SJS and TEN were found to be significantly associated with HLA-A*33:03 and HLA-C*03:02 alleles in both groups of studies with matched controls and population controls. All of the pooled ORs were not significantly affected by the remaining studies and different modeling methods, indicating robust results.

CONCLUSION

A strong association was found between HLA-A*33:03 and HLA-C*03:02 alleles and allopurinol-induced SJS or TEN, especially in an Asian population.

Allopurinol-induced toxic epidermal necrolysis featuring almost 60% skin detachment

RATIONALE

Toxic epidermal necrolysis (TEN) is a life-threatening, immunologically mediated, and usually drug-induced disease. Rarely, clinical pharmacists participating in finding the etiology have been reported.

PATIENTS CONCERNS

A 33-year-old male presented to the emergency department with a 1-day history of fever and rash. The patient, being newly diagnosed with gout 10 days ago, received allopurinol at a dose of 250 mg by mouth daily. After 10 days' exposure to allopurinol, the patient manifested with an "influenza-like" prodromal phase (fever of 38°C, throat pains), which was treated with amoxicillin and nonsteroidal anti-inflammatory drugs of the oxicam type. The next day, he developed a worsening fever of 39.5°C, accompanied by a pruriginous rash all over his body.

DIAGNOSIS

On physical examination, we observed coalescing dusky red macules over >60% of his body surface area, with blisters and detachment of large sheets of necrolytic epidermis all over his chest and face. The diagnosis of TEN was confirmed.

INTERVENTIONS

The patient recovered following treatment with short-term high-dose methylprednisolone sodium succinate, immunoglobulin therapy, topical medication, and supportive therapy.

OUTCOMES

He showed a slow but progressive improvement both in symptoms and cutaneous manifestations. Reepithelization of the skin was achieved after 3 weeks.

LESSONS

Drug-induced-TEN is potentially fatal. This case underlines the necessity of asking medication history in detail and detecting related drug gene to correctly identify the cause of TEN.

Association Between HLA-B*1301 and Dapsone-Induced Cutaneous Adverse Drug Reactions: A Systematic Review and Meta-analysis

Importance

Dapsone-induced hypersensitivity syndrome (DHS) is a life-threatening adverse drug reaction. Based on available epidemiologic studies, HLA genotypes may play an important role in DHS.

Objective

To assess the association between HLA-B*1301 and dapsone-induced cutaneous adverse drug reactions (cADRs).

Data Sources

Human studies investigating associations between HLA-B*1301 and dapsone-induced cADRs were systematically searched without language restriction from the inception of each database until September 12, 2017, in PubMed, the Human Genome Epidemiology Network), and the Cochrane Library. Combinations of HLA genotypes, dapsone, and synonymous terms were used; reference lists were searched in selected articles.

Study Selection

Two reviewers identified studies investigating the associations between HLA-B*1301 and dapsone-induced cADRs that reported sufficient data for calculating the frequency of HLA-B*1301 carriers among case and control patients, in which all patients received dapsone before HLA-B*1301 screening. An initial search of the databases identified 391 articles, of which 3 studies (2 in Chinese populations and 1 in a Thai population) met the inclusion criteria.

Data Extraction and Synthesis

Overall odds ratios (ORs) with 95% CIs were calculated using a random-effects model to determine the association between HLA-B*1301 and dapsone-induced cADRs. Subgroup analyses by type of cADR were also performed. PRISMA guidelines were used to abstract and assess data.

Main Outcomes and Measures

Primary outcomes were associations between HLA-B*1301 and dapsone-induced cADRs in dapsone-tolerant controls. The outcomes are reported as overall OR. Statistical heterogeneity was assessed using the Q statistic and I2 tests.

Results

From the 3 included studies, there were 111 unique patients with dapsone-induced cADRs (subsequently used in the meta-analysis), 1165 dapsone-tolerant patients, and 3026 healthy controls. The cases included 64 men and 49 women (2 patients were missing from the meta-analysis; 1 each from 2 of the 3 studies); mean age was 39.7 years. An association between HLA-B*1301 and dapsone-induced cADRs was identified (summary OR, 43.0; 95% CI, 24.0-77.2). Subgroup analyses among types of cADRs produced similar findings in DHS (OR, 51.7; 95% CI, 16.9-158.5), dapsone-induced severe cADRs (Stevens-Johnson syndrome and toxic epidermal necrolysis [SJS/TEN] plus drug rash [adverse skin reaction to a drug] along with eosinophilia and systemic symptoms [DRESS]) (OR, 54.0; 95% Cl, 8.0-366.2), dapsone-induced SJS/TEN (OR, 40.5; 95% CI, 2.8-591.0), and dapsone-induced DRESS (OR, 60.8; 95% CI, 7.4-496.2). There was no heterogeneity (I2 = 0%, P = .38).

Conclusions and Relevance

Associations between HLA-B*1301 and dapsone-induced cADRs were found in dapsone-tolerant and healthy control groups. For patient safety, genetic screening for HLA-B*1301 in Asian populations before dapsone therapy is warranted.

Hyperuricemia in Children and Adolescents: Present Knowledge and Future Directions

Recent evidence suggests that hyperuricemia is an important condition in children and adolescents, particularly in association with noncommunicable diseases. This review aims to summarize our current understanding of this condition in pediatric patients. An analysis of serum uric acid reference values in a healthy population indicates that they increase gradually with age until adolescence, with differences between the sexes arising at about 12 years of age. This information should be taken into consideration when defining hyperuricemia in studies. Gout is extremely rare in children and adolescents, and most patients with gout have an underlying disease. The major causes of hyperuricemia are chronic conditions, including Down syndrome, metabolic or genetic disease, and congenital heart disease, and acute conditions, including gastroenteritis, bronchial asthma (hypoxia), malignant disorders, and drug side effects. The mechanisms underlying the associations between these diseases and hyperuricemia are discussed, together with recent genetic information. Obesity is a major cause of hyperuricemia in otherwise healthy children and adolescents. Obesity is often accompanied by metabolic syndrome; hyperuricemia in obese children and adolescents is associated with the components of metabolic syndrome and noncommunicable diseases, including hypertension, insulin resistance, dyslipidemia, and chronic kidney disease. Finally, strategies for the treatment of hyperuricemia, including lifestyle intervention and drug administration, are presented.

Hypersensitivity and Cardiovascular Risks Related to Allopurinol and Febuxostat Therapy in Asians: A Population-Based Cohort Study and Meta-Analysis

The safety of newer xanthine oxidase inhibitor febuxostat compared to allopurinol remains unclear. To compare the risks of allopurinol hypersensitivity and febuxostat hypersensitivity and cardiovascular diseases (CVDs) in Asians, we conducted a population-based cohort study enrolling patients receiving allopurinol or febuxostat from Chang Gung Memorial Hospital Health System across Taiwan during 2012-2016 and further performed a meta-analysis incorporating two recent studies. Among the 61,539 users, a corresponding 12,007 and 5,680 patients were identified as new users. The overall incidence of febuxostat hypersensitivity was significantly lower than allopurinol hypersensitivity (0.2 vs. 2.7 per 1,000 new users; P < 0.001). There were 33 allopurinol-hypersensitivity reactions (including 18 severe cutaneous adverse drug reactions), and only one patient developed febuxostat-maculopapular exanthema. Moreover, febuxostat did not statistically increase the risk of CVD (hazard ratio (HR), 1.16; P = 0.152) and related death (HR, 1.49; P = 0.496) compared to allopurinol. The result of the meta-analysis also showed a consistent result. In conclusion, the incidence and severity of febuxostat-hypersensitivity are lower than with allopurinol. Febuxostat did not show an increased risk of CVD and related death.