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

Clinical observation and analysis of rash caused by lacosamide in children with epilepsy

PURPOSE

To draw clinical attention to rashes caused by lacosamide.

METHODS

This retrospective analysis included patients admitted to the Department of Pediatrics, Second Affiliated Hospital of Xi'an Jiaotong University between January 2021 and September 2023. We focused on patients who developed rashes after lacosamide treatment and analyzed all patients who exhibited rashes after lacosamide treatment to analyze the risk factors.

RESULTS

In total, 190 patients received lacosamide, of whom four developed allergies (2.1 %). Three patients had severe rashes, and two patients had high fever. All of these adverse events improved after the withdrawal of lacosamide. Of the 13 patients reported to date, including the four patients in this study, eight used various antiseizure medicines, including seven patients who used four or more antiseizure medicines. Four patients underwent testing for HLA-B*1502, and two patients were positive. Patients developed rashes within 1-10 days after treatment initiation, and the duration of the rash ranged 2-37 days.

CONCLUSIONS

Lacosamide-induced rash was detected in 2.1 % of patients in our cohort. Rashes are potentially serious, and prompt evaluation is required. Rashes are more likely to occur when multiple antiseizure medicines are used simultaneously, typically within 10 days of treatment initiation.

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 Stevens-Johnson Syndrome (SJS)

Allopurinol is a commonly used medication that lowers uric acid production which is essential for gout treatment and prevention. Although many patients tolerate allopurinol therapy without severe complications; Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are life-threatening delayed hypersensitivity reactions that have been reported especially among Asian and African American patients. We describe a case of allopurinol-induced SJS in a 95-year-old Asian female. The patient started allopurinol 13 days prior to presenting to the emergency room (ER). On day 10 of therapy, the patient developed a diffuse erythematous desquamating rash which prompted her to visit the ER after 3 days from the rash onset. This case report describes a rare fatal hypersensitivity reaction that requires rapid identification and treatment in a multi-disciplinary setting.

DNA methylation of ITGB2 contributes to allopurinol hypersensitivity

BACKGROUNDS

HLA-B*58:01 allele was strongly associated with allopurinol induced severe cutaneous adverse drug reaction (SCAR). However, HLA-B genotype is not sufficient to predict the occurrence of allopurinol-induced SCAR.

OBJECTIVE

To discover DNA methylation markers for allopurinol-induced SCAR which may improve the prediction accuracy of genetic testing.

STUDY DESIGN

The study was designed as a retrospective case-control clinical study in multicenter hospitals across Taiwan, Mainland China, Malaysia and Canada. 125 cases of allopurinol-induced SCAR patients and 139 cases of allopurinol tolerant controls were enrolled in this study during 2005 to 2021.

RESULTS

The results of genome-wide DNA methylation assay of 62 patients revealed that ITGB2 showed strong discriminative ability of allopurinol-induced SCAR in both HLA-B*58:01 positive and negative patients with AUC value of 0.9364 (95% CI 0.8682-1.000). In validation study, significant hypermethylation of ITGB2 were further validated in allopurinol-induced SCAR patients compared to tolerant controls, especially in those without HLA-B*58:01(AUC value of 0.8814 (95% CI 0.7121-1.000)). Additionally, the methylation levels of 2 sites on ITGB2 were associated with SCAR phenotypes. Combination of HLA-B*58:01 genotyping and ITGB2 methylation status could improve the prediction accuracy of allopurinol-induced SCAR with the AUC value up to 0.9387 (95% CI 0.9089-0.9684), while the AUC value of HLA-B*58:01 genotyping alone was 0.8557 (95% CI 0.8030-0.9083).

CONCLUSIONS

Our study uncovers differentially methylated genes between allopurinol-induced SCAR patients and tolerant controls with positive or negative HLA-B*58:01 allele and provides the novel epigenetic marker that improves the prediction accuracy of genetic testing for prevention of allopurinol-induced SCAR.

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.

Incidence of allopurinol-induced severe cutaneous adverse drug reaction in Malaysia

AIMS

Allopurinol is known to cause severe cutaneous adverse drug reactions (SCAR) in Malaysia. However, the incidence of allopurinol-induced SCAR is unknown. Therefore, we aimed to determine the incidence of allopurinol-induced SCAR in Malaysia over 5 years from 2015 to 2019.

METHODS

This retrospective analysis was done in collaboration with the National Pharmaceutical Regulatory Agency (NPRA). All allopurinol-induced adverse drug reaction cases reported to NPRA from 2015 to 2019 were extracted. Allopurinol-induced SCAR cases were identified and the incidence over the 5 years was calculated.

RESULTS

Incidence of allopurinol-induced SCAR averaged at 2.5 cases per 1000 new users over the 5-year period, with a reducing trend from 3.2 per 1000 new users in 2015 to 2.25 per 1000 in 2019; despite the increasing number of adverse drug reaction cases being reported over the years. Stevens-Johnson syndrome was the commonest form of allopurinol-induced SCAR reported, at 143 cases (46.8% of total SCAR reported). Among Malaysia's 3 main ethnicities, the Chinese had the highest percentages of allopurinol-induced SCAR when compared to the Bumiputera and Indians (3.18 × 10^-4 %).

CONCLUSION

The estimated incidence of allopurinol-induced SCAR in Malaysia from 2015 to 2019 was 2.5 cases per 1000 new users. This figure is consistent with the incidence reported in other Asian countries, namely Taiwan and Thailand.

Translational Pharmacogenomics: Discovery, Evidence Synthesis and Delivery of Race-Conscious Medicine

Response to medications, the principal treatment modality for acute and chronic diseases, is highly variable, with 40-70% of patients exhibiting lack of efficacy or adverse drug reactions. With ~ 15-30% of this variability explained by genetic variants, pharmacogenomics has become a valuable tool in our armamentarium for optimizing treatments and is poised to play an increasing role in clinical care. This review presents the progress made toward elucidating genetic underpinnings of drug response including discovery of race/ancestry-specific pharmacogenetic variants and discusses the current evidence and evidence framework for actionability. The review is framed in the context of changing demographics and evolving views related to race and ancestry. Finally, it highlights the vital role played by cohort studies in elucidating genetic differences in drug response across race and ancestry and the informal collaborations that have enabled the field to bridge the "bench to bedside" translational gap.