Oxcarbazepine-induced Stevens-Johnson syndrome: a case report

Analysis of clinical features of oxcarbazepine-induced Stevens-Johnson syndrome and toxic epidermal necrolysis

Background

Stevens-Johnson syndrome (SJS) is considered a hypersensitivity syndrome affecting the skin and mucous membranes. It has been reported that an anticonvulsant drug, oxcarbazepine, may cause Stevens-Johnson syndrome and toxic epidermal necrolysis (TEN). However, the clinical features of oxcarbazepine-induced Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) remain ambiguous. This article aims to explore the clinical features of SJS/TEN.

Methods

Systematic searches of several Chinese and English databases were conducted for case reports published on PubMed, EMBASE, Web of Science, MEDLINE, CNKI from January 1, 2007 to March 1, 2023.

Results

A total of seventeen patients (10 males and 7 females) were included in this study, including nine adult patients and eight pediatric patients. The results showed that males seem to have a higher prevalence of SJS/TEN than females, and SJS/TEN usually occurs within 2 weeks after administration of oxcarbazepine (OXC). The main clinical manifestations among the included patients were rashes or maculopapules (17 cases, 100%), fever (11 cases, 64.7%), mucosal lesions (15 cases, 88.2%), conjunctivitis with/without ocular discharge (12 cases, 70.6%), and blisters (12 cases, 70.6%). After stopping OXC or switching to other drugs that treat primary disease as well as treatment with IVIG, glucocorticoid, anti-allergy, and fluid replacement, eight of the included patients recovered completely, and another eight of the included patients reported symptomatic improvement, while the prognosis of one of the included patients was not reported.

Conclusion

Diverse clinical signs and symptoms of SJS/TEN might result in misinterpretation and delayed diagnosis. It should be identified and treated immediately to avoid significant consequences and potentially jeopardize patients' lives.

Oxcarbazepine-induced toxic epidermal necrolysis in lupus erythematosus: Turning into a "frequent" rarity but is it diagnosing that matters?

Classic Toxic Epidermal Necrolysis (TEN) in Lupus Erythematosus (LE) is rare and that caused by oxcarbazepine is even rarer. It can be triggered/induced by various insults, the most prominent being drugs. Herein, we describe a young female, a diagnosed case of LE with lupus nephritis, with recent-onset central nervous system vasculitis (incidentally detected on neuroimaging while she was being evaluated for a recent-onset behavioural change), who within a month of exposure to the drug developed an extensive exfoliating skin rash with mucosal lesions, which on histopathological evaluation showed TEN in LE, triggered by Oxcarbazepine, which was commenced for seizure prophylaxis. She was managed with pulse methylprednisolone, followed by intravenous immunoglobulin (IVIg), after which she made a satisfactory recovery. It is highlighted that TEN in LE patterns must be recognized in an emergency and Acute Syndrome of Apoptotic Panepidermolysis (ASAP) concept applied promptly without awaiting diagnoses. Further, many common drugs possibly trigger this pathology making the rara-avis not rare anymore!

Analysis of trends and factors determining initial antiseizure medication choice for epilepsy in Taiwan

PURPOSE

To evaluate the current trends and factors associated with the first anti-seizure medications (ASMs) prescribed for epilepsy in Taiwan.

METHODS

Data for patients with epilepsy were collected from the National Health Insurance Research Database, a population-based claims database. We selected patients with newly diagnosed epilepsy from 2013 to 2016. Multivariate logistic regression was used to examine the factors associated with the selection of newer ASMs for the first prescription.

RESULTS

A total of 73,891 patients with newly diagnosed epilepsy were eligible for the study, and the annual incidence was approximately 0.79 per 1,000 people. The five ASMs most prescribed for monotherapy were valproic acid, phenytoin, levetiracetam, gabapentin, and oxcarbazepine, accounting for nearly 90% of all ASMs. Valproic acid was the most-prescribed ASM (more than 30%), and levetiracetam has replaced phenytoin as the second choice since 2015. Factors associated with the selection of newer ASMs for the first prescription were patients' year of diagnosis, gender, socioeconomic level, and previous or existing comorbidities and the profiles of the care providers (accreditation level, service volume, geographic location, and degree of urbanization of the surrounding area).

CONCLUSION

The data indicated that the trends in ASMs first prescribed for patients in Taiwan accorded with most of the international epilepsy treatment guidelines. However, there were some differences between our results and those in developed countries. In addition, we observed a large urban-rural disparity in the administration of ASMs.

Oxcarbazepine induces mitotic catastrophe and apoptosis in NRK-52E proximal tubular cells

Certain medicines including anticancer drugs, NSAIDs and antiepileptic drugs are known to cause drug-induced nephropathy. For example, antiepileptic drugs such as carbamazepine (CBZ) and valproic acid have been reported to cause damage to the proximal tubular cells. Although there has been a great deal of research concerning the nephrotoxicity of CBZ, little is known about that of oxcarbazepine (OXC), a derivative of CBZ. To investigate the molecular mechanism underlying renal proximal tubular cell death caused by OXC, we examined alterations in the gene expression profile of NRK-52E proximal tubular cells during OXC exposure. DNA microarray analysis revealed that the levels of genes related to mitotic processes including chromosomal and cytoplasmic segregation, progression to G2/M phase, and formation of the mitotic spindle are increased after exposure to 50 μM OXC for 6 h. Cell cycle analysis by flow cytometry showed that OXC at concentrations between 25 and 100 μM induces G2/M arrest. We also found that OXC significantly increases histone H3 phosphorylation, indicative of mitotic cells. These results imply that OXC induces cell cycle arrest at the mitotic phase. Immunofluorescence analysis showed monopolar spindles, which are formed in response to centrosome separation defects, in OXC-treated cells. We also show that OXC suppresses the phosphorylation of PLK1, which is involved not only in the activation of the kinesin family of motor proteins for centrosome separation and bipolar spindle assembly, but also in the cleavage of centrosomal proteins. Thus, our results indicate that OXC inhibits centrosome separation by reducing the activation of PLK1, which leads to the formation of an abnormal spindle and induces mitotic catastrophe and apoptosis in NRK-52E cells.

Association between HLA-A*3201 allele and oxcarbazepine-induced cutaneous adverse reactions in Eastern Han Chinese population

PURPOSE

To determine genetic associations between oxcarbazepine (OXC)-induced cutaneous adverse drug reactions (cADRs) and human leukocyte antigen (HLA) variants in the Eastern Han Chinese population.

METHODS

A total of 120 patients were enrolled in this study, including 30 subjects with OXC-induced cADRs (case group) and 90 OXC-tolerant patients (control group). High-resolution HLA genotyping was conducted for HLA-A, HLA-B, HLA-C, and HLA-DRB1, and allele frequencies were compared.

RESULTS

No patient carried the HLA-B *1502 allele in the case group, the frequency of HLA-B *1502 allele in the control group was 6.1%. HLA-A*3201 allele was detected in 13.3% of 30 patients with OXC-induced cADRs (4/30) and 0% of 90 OXC-tolerant patients (0/90). The difference in HLA-A*3201 frequency between the two groups was statistically significant [P = 0.004, odds ratio (OR) = 15.877, 95% confidence interval (CI) = 1.817-138.720].

CONCLUSIONS

Eastern Han Chinese patients with the HLA-A*3201 allele may be more susceptible to OXC-induced cADRs, while the HLA-B*1502 allele is not correlated with it. The precise association between HLA alleles and OXC-induced cADRs warrants further study.

Applications of Immunopharmacogenomics: Predicting, Preventing, and Understanding Immune-Mediated Adverse Drug Reactions

Adverse drug reactions (ADRs) are a significant health care burden. Immune-mediated adverse drug reactions (IM-ADRs) are responsible for one-fifth of ADRs but contribute a disproportionately high amount of that burden due to their severity. Variation in human leukocyte antigen ( HLA) genes has emerged as a potential preprescription screening strategy for the prevention of previously unpredictable IM-ADRs. Immunopharmacogenomics combines the disciplines of immunogenomics and pharmacogenomics and focuses on the effects of immune-specific variation on drug disposition and IM-ADRs. In this review, we present the latest evidence for HLA associations with IM-ADRs, ongoing research into biological mechanisms of IM-ADRs, and the translation of clinical actionable biomarkers for IM-ADRs, with a focus on T cell-mediated ADRs.

HLAs: Key regulators of T-cell-mediated drug hypersensitivity

Adverse drug reactions (ADR) can be broadly categorised as either on-target or off-target. On-target ADRs arise as a direct consequence of the pharmacological properties of the drug and are therefore predictable and dose-dependent. On-target ADRs comprise the majority (>80%) of ADRs, relate to the drug's interaction with its known pharmacological target and are a result of a complex interplay of genetic and ecologic factors. In contrast, off-target ADRs, including immune-mediated ADRs (IM-ADRs), are due to unintended pharmacological interactions such as inadvertent ligation of host cell receptors or non-pharmacological interactions mediated through an adaptive immune response. IM-ADRs can be classified according to the primary immune cell involved and include B-cell-mediated (Gell-Coombs type I-III reactions) and T-cell-mediated (Gell-Coombs type IV or delayed hypersensitivity) reactions. IM-ADRs mediated by T cells are associated with phenotypically distinct clinical diagnoses and can vary from a mild delayed rash to a life-threatening cutaneous, systemic or organ disease, such as Stephen Johnson syndrome/toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms and drug-induced liver disease. T-cell-mediated ADRs are strongly linked to the carriage of particular HLA risk alleles which are in the case of abacavir hypersensitivity and HLA-B*57:01 has led to translation into the clinic as a routine screening test. In this review, we will discuss the immunogenetics and pathogenesis of IM-ADRs and how HLA associations inform both pre-drug screening strategies and mechanistic understanding.

Severe Delayed Drug Reactions: Role of Genetics and Viral Infections

Adverse drug reactions (ADRs) are a significant source of patient morbidity and mortality and represent a major burden to health care systems and drug development. Up to 50% of such reactions are preventable. Although many ADRs can be predicted based on the on-target pharmacologic activity, ADRs arising from drug interactions with off-target receptors are recognized. Off-target ADRs include the immune-mediated ADRs (IM-ADRs) and pharmacologic drug effects. In this review, we discuss what is known about the immunogenetics and pathogenesis of IM-ADRs and the hypothesized role of heterologous immunity in the development of IM-ADRs.

Pharmacogenomics of off-target adverse drug reactions

Off-target adverse drug reactions (ADRs) are associated with significant morbidity and costs to the healthcare system, and their occurrence is not predictable based on the known pharmacological action of the drug's therapeutic effect. Off-target ADRs may or may not be associated with immunological memory, although they can manifest with a variety of shared clinical features, including maculopapular exanthema, severe cutaneous adverse reactions (SCARs), angioedema, pruritus and bronchospasm. Discovery of specific genes associated with a particular ADR phenotype is a foundational component of clinical translation into screening programmes for their prevention. In this review, genetic associations of off-target drug-induced ADRs that have a clinical phenotype suggestive of an immunologically mediated process and their mechanisms are highlighted. A significant proportion of these reactions lack immunological memory and current data are informative for these ADRs with regard to disease pathophysiology, therapeutic targets and biomarkers which may identify patients at greatest risk. Although many serious delayed immune-mediated (IM)-ADRs show strong human leukocyte antigen associations, only a small subset have successfully been implemented in screening programmes. More recently, other factors, such as drug metabolism, have been shown to contribute to the risk of the IM-ADR. In the future, pharmacogenomic targets and an understanding of how they interact with drugs to cause ADRs will be applied to drug design and preclinical testing, and this will allow selection of optimal therapy to improve patient safety.

Antiepileptic Drugs-induced Stevens-Johnson syndrome: A case Series

Stevens-Johnson syndrome (SJS) is an acute life-threatening mucocutaneous reaction, characterized by extensive necrosis and detachment of the epidermis from the skin. The overall incidence of SJS is seen in five cases per million people per year. SJS is typically caused by drugs and is a kind of idiosyncratic reaction. Adverse drug reactions such an SJS have a remarkable effect on patient's safety issues. We encountered nine cases of antiepileptic drug (AED)-induced SJS, specifically with carbamazepine, oxcarbazepine, and phenytoin. To manage the reaction, the clinician withdrew the drug in all 8 cases, and in 1 case, the patient was shifted to valproate and symptomatic treatment was provided. There is still a controversy whether or not all AEDs can cause SJS. Recent studies have investigated the role of genetic factors - HLAB*502 allele in the development of AED-induced SJS in patients of Asian ancestry.

Evolving models of the immunopathogenesis of T cell-mediated drug allergy: The role of host, pathogens, and drug response

Immune-mediated (IM) adverse drug reactions (ADRs) are an underrecognized source of preventable morbidity, mortality, and cost. Increasingly, genetic variation in the HLA loci is associated with risk of severe reactions, highlighting the importance of T-cell immune responses in the mechanisms of both B cell-mediated and primary T cell-mediated IM-ADRs. In this review we summarize the role of host genetics, microbes, and drugs in IM-ADR development; expand on the existing models of IM-ADR pathogenesis to address multiple unexplained observations; discuss the implications of this work in clinical practice today; and describe future applications for preclinical drug toxicity screening, drug design, and development.

Oxcarbazepine induced toxic epidermal necrolysis - a rare case report

Carbamazepine, is well known to cause Stevens–Johnson syndrome and toxic epidermal necrolysis(TEN). Oxcarbazepine, a 10-keto analog of carbamazepine, is an anticholinergic, anticonvulsant and mood stabilizing drug, used primarily in the treatment of epilepsy. Its efficacy is similar to carbamazepine but allergic reactions and enzyme induction is low. We describe a case of oxcarbazepine induced TEN, who presented with erythematous ulcerative maculopapular rash.

HLA-B allele and haplotype diversity among Thai patients identified by PCR-SSOP: evidence for high risk of drug-induced hypersensitivity

Background: There are 3 classes of HLA molecules; HLA class I, II and III, of which different classes have different functions. HLA-B gene which belongs to HLA class I play an important role predicting drug hypersensitivity.

Materials and Methods: Nine hundred and eighty-six Thai subjects who registered at a pharmacogenomics laboratory were determined for HLA-B genotype using a two-stage sequence-specific oligonucleotide probe system (PCR-SSOP).

Results: In this study, HLA-B alleles did not deviate from Hardy-Weinberg equilibrium (P > 0.05). The most common HLA-B alleles observed in this population were HLA-B^*46:01 (11.51%), HLA-B^*58:01 (8.62%), HLA-B^*40:01 (8.22%), HLA-B^*15:02 (8.16%) and HLA-B^*13:01 (6.95%). This finding revealed that HLA-B allele frequency in the Thai population was consistent with the Chinese population (p > 0.05), however, differed from the Malaysian population (p < 0.05). The top five HLA-B genotypes were HLA-B^*40:01/46:01 (2.13%), HLA-B^*46:01/46:01 (2.03%), HLA-B^*40:01/58:01 (2.03%), HLA-B^*46:01/58:01 (1.93%) and HLA-B^*15:02/46:01 (1.83%). This study found that 15.92% of Thai subjects carry HLA-B^*15:02, which has been associated with carbamazepine-induced severe cutaneous adverse drug reactions (SCARs). Moreover, 16.33% of Thai subjects carry the HLA-B^*58:01 allele, which has been associated with allopurinol-induced SCARs.

Conclusion: This study demonstrates a high diversity of HLA-B polymorphisms in this Thai population. The high frequency of HLA-B pharmacogenomic markers in the population emphasizes the importance of such screening to predict/avoid drug hypersensitivity.

Human leukocyte antigen typing using a knowledge base coupled with a high-throughput oligonucleotide probe array analysis

Human leukocyte antigens (HLA) are important biomarkers because multiple diseases, drug toxicity, and vaccine responses reveal strong HLA associations. Current clinical HLA typing is an elimination process requiring serial testing. We present an alternative in situ synthesized DNA-based microarray method that contains hundreds of thousands of probes representing a complete overlapping set covering 1,610 clinically relevant HLA class I alleles accompanied by computational tools for assigning HLA type to 4-digit resolution. Our proof-of-concept experiment included 21 blood samples, 18 cell lines, and multiple controls. The method is accurate, robust, and amenable to automation. Typing errors were restricted to homozygous samples or those with very closely related alleles from the same locus, but readily resolved by targeted DNA sequencing validation of flagged samples. High-throughput HLA typing technologies that are effective, yet inexpensive, can be used to analyze the world's populations, benefiting both global public health and personalized health care.

Clinical pharmacogenetics implementation consortium guidelines for CYP2C9 and HLA-B genotypes and phenytoin dosing

Phenytoin is a widely used antiepileptic drug with a narrow therapeutic index and large interpatient variability, partly due to genetic variations in the gene encoding cytochrome P450 (CYP)2C9 (CYP2C9). Furthermore, the variant allele HLA-B*15:02, encoding human leukocyte antigen, is associated with an increased risk of Stevens-Johnson syndrome and toxic epidermal necrolysis in response to phenytoin treatment. We summarize evidence from the published literature supporting these associations and provide recommendations for the use of phenytoin based on CYP2C9 and/or HLA-B genotype (also available on PharmGKB: http://www.pharmgkb.org). The purpose of this guideline is to provide information for the interpretation of HLA-B and/or CYP2C9 genotype tests so that the results can guide dosing and/or use of phenytoin. Detailed guidelines for the use of phenytoin as well as analyses of cost-effectiveness are out of scope. Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines are periodically updated at http://www.pharmgkb.org.

Pharmacogenetics of antiepileptic drug-induced hypersensitivity

Antiepileptic drugs can induce potentially life-threatening hypersensitivity reactions such as Stevens–Johnson syndrome at a frequency of one in 10,000 to one in 1000 treated patients. There is a considerable cross-reactivity among different antiepileptic drugs but the mechanisms are not known. In this review we have summarized current evidence on antiepileptic drug-induced hypersensitivity reactions and performed meta-analyses of published case–control studies that investigated associations between HLA alleles and several antiepileptic drugs in diverse populations. As the heterogeneity between studies was high, we conducted subsequent subgroup analyses and showed that HLA-B*15:02 was associated with carbamazepine, lamotrigine and phenytoin-induced Stevens–Johnson syndrome in Asian populations indicating that pretreatment testing may prevent cross-reactivity. Additionally, we explored the potential of new, high-throughput technologies that may help to understand the mechanisms and predict the risk of adverse drug reactions in the future.

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.

Clinical Pharmacogenetics Implementation Consortium guidelines for HLA-B genotype and carbamazepine dosing

Human leukocyte antigen B (HLA-B) is a gene that encodes a cell surface protein involved in presenting antigens to the immune system. The variant allele HLA-B*15:02 is associated with an increased risk of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) in response to carbamazepine treatment. We summarize evidence from the published literature supporting this association and provide recommendations for the use of carbamazepine based on HLA-B genotype (also available on PharmGKB: http://www.pharmgkb.org). The purpose of this article is to provide information to allow the interpretation of clinical HLA-B*15:02 genotype tests so that the results can be used to guide the use of carbamazepine. The guideline provides recommendations for the use of carbamazepine when HLA-B*15:02 genotype results are available. Detailed guidelines regarding the selection of alternative therapies, the use of phenotypic tests, when to conduct genotype testing, and cost-effectiveness analyses are beyond the scope of this document. Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines are published and updated periodically on the PharmGKB website at (http://www.pharmgkb.org).

HLA and pharmacogenetics of drug hypersensitivity

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

Oxcarbazepine-induced Stevens Johnson syndrome: A rare case report

Although carbamazepine is the most common cause of Stevens Johnson syndrome (SJS) a new antiepileptic drug, oxcarbazepine which is structurally related to carbamazepine, has also been rarely shown to induce SJS. Here we report a case with SJS, which was induced by oxcarbazepine.

Cutaneous reactions induced by oxcarbazepine in Southern Han Chinese: incidence, features, risk factors and relation to HLA-B alleles

PURPOSE

Oxcarbazepine (OXC) is a promising alternative for patients who cannot tolerate carbamazepine. Recently, however, it has been reported that OXC-induced cutaneous adverse drug reactions (cADRs) are prevalent and may lead to drug discontinuation. Additionally, these reactions are thought to be associated with HLA-B*1502. This study aims to investigate the incidence, features and risk factors of OXC-cADRs, and to explore their relation to HLA-B alleles in Southern Han Chinese.

METHODS

A prospective study was performed to investigate the incidence, features and risk factors of OXC-cADRs, in which 252 new users were recruited. To examine the association between OXC-cADRs and HLA-B alleles, 14 maculopapular eruption (MPE) cases, including 9 additional cases beyond this prospective observation, were genotyped by PCR-SSP and sequencing. Thirty-five OXC-tolerant patients served as controls.

RESULTS

Five patients (2.0%) developed an OXC-cADR, and all were mild MPE. History of other AED allergy (p=0.005, OR=121.23) and non-AED allergy (p=0.006, OR=59.92) were significant risk factors for OXC-cADRs in multivariate logistic regression analysis. Only one patient with OXC-MPE was positive for HLA-B*1502; and the frequency of HLA-B*1502 in OXC-MPE did not differ significantly from that in OXC-tolerant controls. Four HLA-B*1302 alleles were detected in OXC-MPE cases, which was significantly different from that in general population of southern Han Chinese (p=0.001, OR=7.83).

CONCLUSIONS

The incidence of OXC-induced cADRs was low, and no severe reactions occurred. Patients with a history of allergy are more susceptible to OXC-cADRs. No significant association between HLA-B*1502 and OXC-MPE was found. The associations between OXC-MPE and HLA alleles warrant further studies.

Direct interaction between HLA-B and carbamazepine activates T cells in patients with Stevens-Johnson syndrome

BACKGROUND

Increasing studies have revealed that HLA alleles are the major genetic determinants of drug hypersensitivity; however, the underlying molecular mechanism remains unclear.

OBJECTIVE

We adopted the HLA-B∗1502 genetic predisposition to carbamazepine (CBZ)-induced Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) as a model to study the pathologic role of HLA in delayed-type drug hypersensitivity.

METHODS

We in vitro expanded CBZ-specific cytotoxic T lymphocytes (CTLs) from patients with CBZ-induced SJS/TEN and analyzed the interaction between HLA-B and CBZ analogs based on CTL response, surface plasmon resonance, peptide-binding assay, site-directed mutagenesis, and computer modeling.

RESULTS

The endogenous peptide-loaded HLA-B∗1502 molecule presented CBZ to CTLs without the involvement of intracellular drug metabolism or antigen processing. The HLA-B∗1502/peptide/β(2)-microglobulin protein complex showed binding affinity toward chemicals sharing 5-carboxamide on the tricyclic ring, as with CBZ. However, modifications of the ring structure of CBZ altered HLA-B∗1502 binding and CTL response. In addition to HLA-B∗1502, other HLA-B75 family members could also present CBZ to activate CTLs, whereas members of the HLA-B62 and HLA-B72 families could not. Three residues (Asn63, Ile95, and Leu156) in the peptide-binding groove of HLA-B∗1502 were involved in CBZ presentation and CTL activation. In particular, Asn63 shared by members of the B75 family was the key residue. Computer simulations revealed a preferred molecular conformation of the 5-carboxamide group of CBZ and the side chain of Arg62 on the B pocket of HLA-B∗1502.

CONCLUSIONS

This study demonstrates a direct interaction of HLA with drugs, provides a detailed molecular mechanism of HLA-associated drug hypersensitivity, and has clinical correlations for CBZ-related drug-induced SJS/TEN.

Recurrence and outcomes of Stevens-Johnson syndrome and toxic epidermal necrolysis in children

OBJECTIVES

To report clinical course, etiology, management, and long-term outcomes of children suffering from Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN).

METHODS

We conducted a study of all pediatric patients with SJS or TEN admitted between 2000 and 2007 to the Hospital for Sick Children and Children's Hospital Boston, and particular attention was paid to clinical manifestations, etiology, mortality, and long-term outcomes.

RESULTS

We identified 55 cases of SJS (n = 47), TEN (n = 5), or SJS/TEN overlap syndrome (n = 3). Drugs were identified as the most likely etiologic agent in 29 children (53%); antiepileptic drugs were the most common agents (n = 16), followed by sulfonamide antibiotics (n = 7) and chemotherapy drugs (n = 2). Acute Mycoplasma pneumoniae infection was confirmed in 12 children (22%), and herpes simplex virus was confirmed in 5 children (9%). Treatment regimens differed significantly between participating sites and included systemic antimicrobial agents (67%), systemic corticosteroids (40%), and antiviral drugs (31%). Intravenous immunoglobulin was administered to 21 children (38%), of whom 8 received concomitant systemic corticosteroids. Ten children (18%) had recurrence of SJS up to 7 years after the index episode, and 3 experienced multiple recurrences. Twenty-six children (47%) suffered long-term sequelae that mostly involved the skin and eyes.

CONCLUSIONS

Mortality rate in children was lower than that reported in adults, but half of affected children suffered long-term complications. The recurrence rate of SJS was high (1 in 5), which suggests vulnerability and potential genetic predisposition. In the absence of standardized management guidelines for these conditions, treatment regimens differed significantly between participating institutions.

Pharmacogenetic screening of carbamazepine-induced severe cutaneous allergic reactions

Recent studies associated the HLA-B 1502 allele with carbamazepine (CBZ)-induced Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) in patients from China, Thailand and Malaysia. No association has been found in patients from Europe or Japan. Linkage summary reports from East and South-east Asia predict a highly significant odds ratio (OR) of 84.75 (95% confidence interval [CI]=42.53-168.91; p=8.96×10[-15]) with sensitivity and negative predictive values of 92% and 98%, respectively. The higher prevalence of HLA-B 1502 allele among certain Asian populations (10-15%) compared to Caucasians (1-2%) may explain a 10-fold to 25-fold higher incidence of CBZ-SJS/TEN in patients from Asia. Screening for HLA-B 1502 before using CBZ can prevent SJS/TEN in certain populations, but screening may be less beneficial in populations with low HLA-B 1502 allele frequency and in patients exposed to CBZ for more than 2 months. A retrospective study demonstrated that the costs of HLA-B 1502 screening were less than those of SJS treatment. This article reviews possible benefits and concerns of HLA-B 1502 screening in clinical practice.

Pilot association study of oxcarbazepine-induced mild cutaneous adverse reactions with HLA-B*1502 allele in Chinese Han population

BACKGROUND

Recent study demonstrated that HLA-B*1502 was a common risk allele in aromatic antiepileptic drugs (AEDs) induced Stevens-Johnson syndrome and toxic epidermal necrolysis in Han Chinese. However, the association of AEDs-induced mild maculopapular eruption (MPE) with HLA-B*1502 remains unclear until recently. In the present study, we conducted a pilot study to detect a possible association of oxcarbazepine (OXC)-induced MPE with HLA-B*1502 allele in Chinese Han population.

METHODS

We enrolled 90 subjects involving 9 patients with OXC-induced MPE and two groups of controls, 9 OXC-tolerant and 72 normal controls. High-resolution HLA genotyping was performed by specific kit. The results of HLA genotyping are expressed as positive or negative for HLA-B*1502 allele. Differences in genotype frequencies between groups were assessed by the Fisher's exact test.

RESULTS

Four cases were detected as positive for HLA-B*1502 amongst 9 patients. However, only 1 subject was positive amongst 9 tolerant controls, and 6 subjects were positive amongst 72 normal controls. The difference in HLA-B*1502 allele frequencies between the MPE group and normal controls was statistically significant (OR: 8.8; 95% CI: 1.853-41.790; P=0.011). In addition, we also observed an increased frequency of HLA-B*1502 allele in patients (44.44%) compared with tolerant controls (11.11%), although it failed to reach statistical significance (P=0.294).

CONCLUSIONS

Our findings indicate that HLA-B*1502 allele may contribute to the genetic susceptibility to OXC-induced MPE in Chinese Han population. In order to safer AEDs use, we recommend that HLA-B*1502 allele should be tested for patients with OXC-induced MPE before changing to other AEDs, and AEDs with similar chemical structure should be avoided in individuals who test positive for HLA-B*1502 allele. It should be pointed out that, however, our results may well be just by chance owing to the small sample size and should be further confirmed in future studies.

Common risk allele in aromatic antiepileptic-drug induced Stevens-Johnson syndrome and toxic epidermal necrolysis in Han Chinese

AIMS

Compared with other categories of drugs, such as antibiotics and NSAIDs, antiepileptic therapies are associated with a high incidence of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). We previously reported that carbamazepine (CBZ)-SJS/TEN is strongly associated with the HLA-B*1502 in Han Chinese, which has been confirmed in other Southeast Asian countries where the allele is prevalent. Here, we extend the study of HLA susceptibility to three different antiepileptic drugs, phenytoin (PHT), lamotrigine (LTG) and oxcarbazepine (OXC), which have structure similarity to CBZ.

MATERIALS & METHODS

We carried out a case-control association study. We enrolled 26 PHT-, six LTG- and three OXC-induced SJS/TEN patients, 113 PHT-tolerant and 67 LTG-tolerant subjects who were on the drug, respectively, for more than 3 months without the adverse reactions, and 93 normal subjects from the general population. The HLA-A, B, C and DRB1 genotypes were determined.

RESULTS

We found that HLA-B*1502 was present in eight out of 26 (30.8%) PHT-SJS/TEN (OR: 5.1; 95% CI: 1.8-15.1; p = 0.0041), two out of six (33%) LTG-SJS (odds ratio [OR]: 5.1; 95% CI: 0.8-33.8; p = 0.1266) and three out of three (100%) OXC-SJS (OR: 80.7; 95% CI: 3.8-1714.4; p = 8.4 x 10(-4)) patients. In addition, HLA-B*1301, Cw*0801 and DRB1*1602 also showed an association with PHT-SJS/TEN (p = 0.0128-0.0281; OR: 3.0-4.3).

CONCLUSION

Our results indicate that OXC, PHT and LTG, which possess an aromatic ring just as CBZ does, when causing SJS/TEN, share a common risk allele. Aromatic antiepileptic drugs causing SJS/TEN in HLA-B*1502 carriers may act on a similar pathogenetic mechanism, although other genetic/nongenetic factor(s) may also contribute to the pathomechanism of the disease. We suggest that aromatic antiepileptic drugs, including CBZ, OXC and PHT, should be avoided in the B*1502 carrier and caution should also be exercised for LTG.

Genetic predisposition of life-threatening antiepileptic-induced skin reactions

IMPORTANCE OF THE FIELD

Recent advances in pharmacogenetic studies have uncovered increasingly more genes that predispose individuals to adverse drug reactions. Aromatic antiepileptic drugs (AEDs) are a frequent cause of severe cutaneous adverse reactions (SCAR). A strong genetic association between HLA-B*1502 and carbamazepine (CBZ)-induced Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) has been shown in Han Chinese patients.

AREAS COVERED IN THIS REVIEW

This article reviews and updates genetic information associated with CBZ and other AEDs causing SCAR in different ethnic populations.

WHAT THE READER WILL GAIN

Independent studies from different countries confirmed that patients carrying the HLA-B*1502 are at high risk of SJS/TEN when exposed to CBZ. The US FDA and similar regulatory agencies in Canada and Taiwan have updated the CBZ drug label to include the genetic information. Available data also suggest that HLA-B*1502 is a risk allele for SJS/TEN caused by other aromatic AEDs with a similar structure to CBZ.

TAKE HOME MESSAGE

Screening for HLA-B*1502 allele before starting treatment with CBZ is justified in patients from high-risk populations as recommended by regulatory agencies. Similar chemicals should also be avoided in individuals who test positive for HLA-B*1502.