Do HLA-A markers predict skin-reactions from aromatic antiepileptic drugs in a Norwegian population? A case control study

Update on HLA-B*15:02 allele associated with adverse drug reactions

HLA alleles, part of the major histocompatibility complex, are strongly associated with adverse drug reactions (ADRs). This review focuses on HLA-B*15:02 and explores its association with ADRs in various ethnic populations and with different drugs, aiming to provide insights into the safe clinical use of drugs and minimize the occurrence of ADRs. Furthermore, the review explores the potential mechanisms by which HLA-B*15:02 may be associated with ADRs, aiming to gain new insights into drug modification and identification of haptens. In addition, it analyzes the frequency of the HLA-B*15:02, genotyping methods, cost-effectiveness and treatment measures for adverse reactions, thereby providing a theoretical basis for formulating clinical treatment plans.

Associations of HLA genetic variants with carbamazepine‐induced cutaneous adverse drug reactions: An updated meta‐analysis

Aggregated risk of carbamazepine (CBZ)‐induced cutaneous adverse drug reactions (cADRs) with different HLA variants are unclear and limited in terms of the power of studies. This study aimed to assess the aggregated risk of CBZ‐induced cADRs associated with carrying the following HLA variants: HLA‐B*15:02, HLA‐B*15:11, HLA‐B*15:21, HLA‐B*38:02, HLA‐B*40:01, HLA‐B*46:01, HLA‐B*58:01, HLA‐A*24:02, and HLA‐A*31:01. Literature was searched in different databases following PRISMA guidelines. The outcomes were measured as odds ratio (OR) using RevMan software by a random/fixed effects model, where p < 0.05 was set as statistical significance. In total, 46 case–control studies met the inclusion criteria and were included in this analysis consisting of 1817 cases and 6614 controls. It was found that case‐patients who carried the HLA‐B*15:02 allele were associated with a significantly increased risk of CBZ‐induced Stevens−Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) compared to controls (OR 26.01; 95% CI 15.88–42.60; p < 0.00001). The aggregated risk of cADRs was slightly higher in Asian compared to Caucasian patients (Asians: OR 14.84; 95% CI 8.95–24.61; p < 0.00001; Caucasians: OR 11.65; 95% CI 1.68–80.70; p = 0.01). Further, HLA‐B*15:11, HLA‐B*15:21, or HLA‐A*31:01 allele was also associated with significantly increased risk of CBZ‐induced cADRs (HLA‐B*15:11: OR 6.08; 95% CI 2.28–16.23; p = 0.0003; HLA‐B*15:21: OR 5.37; 95% CI 2.02–14.28; p = 0.0008; HLA‐A*31:01: OR 5.92; 95% CI 4.35–8.05; p < 0.00001). Other HLA variants were not found to have any significant associations with CBZ‐induced cADRs. Strong associations between the HLA‐B*15:02, HLA‐B*15:11, HLA‐B*15:21, or HLA‐A*31:01 allele with CBZ‐induced cADRs have been established in this analysis. Pharmacogenetic testing of particular HLA alleles before initiation of CBZ therapy may be beneficial to patients and may help to eradicate cADRs substantially.

Rash during lamotrigine treatment is not always drug hypersensitivity: A retrospective cohort study among children and adults

Purpose Cutaneous adverse drug reactions (cADRs) are a major cause of lamotrigine (LTG) discontinuation. Remarkable variation in their reported incidence suggests confounders and diverse terms and definitions. The aim of this study was to identify immunological cADRs and to throw light on classification and differential diagnoses in children and adults. Methods Hospital records of 2683 patients with epilepsy (1897 adults, 786 children) were retrospectively screened. Of these, 403 patients (236 adults, 167 children) with first time exposure to LTG were reviewed. Skin reactions were categorized into possible or probable cADRs due to LTG hypersensitivity, and other skin reactions (OSRs) unlikely to be caused by this mechanism. Results 29 of 403 patients (7.2%) reported emergent skin symptoms within 3 months of treatment with LTG of which 20 (5%: 5.9% adults, 3.6% children) were categorized as possible or probable cADRs. Concomitant infection appeared to be present in several cases, particularly in children. OSRs were found in 4.2% of the children using LTG, compared to 0.8% of the adults (p = 0.04). Conclusions Rash during the early phase of LTG treatment is not always drug hypersensitivity. Whenever skin symptoms occur, other potential causes should receive attention to avoid needless discontinuation, particularly in children. However, when early symptoms and signs of severe cADRs are suspected, LTG should promptly be discontinued.

HLA-A∗24:02 associated with lamotrigine-induced cutaneous adverse drug reactions: A systematic review and meta-analysis

BACKGROUND

Several studies demonstrated a connection between human leukocyte antigen (HLA)-B∗1502 and lamotrigine (LTG)-induced cutaneous adverse drug reactions (cADRs). The correlation between the HLA-A∗24:02 and LTG-cADRs remains controversial. To examine the associations between HLA-A∗24:02 and LTG-cADRs, we conducted a systematic review and meta-analysis.

METHODS

We performed a comprehensive search of the literature in several electronic database systems including Cochrane Library, EMBASE and PubMed from inception to January 2020. Review Manager was used to compare the frequencies of HLA-A∗24:02 carriers between the subgroups.

RESULTS

A total of 5 studies were eligible, including 197 LTD-cADRs, 396 LTD-tolerant controls, and 2068 population controls. Compared with the LTG-tolerant controls, there was a statistically significant association between the HLA-A∗24:02 allele and LTG-induced cADRs (odds ratios: 1.94, 95% confidence intervals 1.06-3.54; P = .03). Compared with the general population, the relationship between the HLA-A∗24:02 genotype and LTG-induced cADRs was statistically significant (summary odds ratios: 2.12, 95% confidence intervals 1.04-4.30; P = .04).

CONCLUSIONS

HLA-A∗24:02 may be a risk factor for LTG-cADRs.

Mechanisms of Severe Cutaneous Adverse Reactions: Recent Advances

Cutaneous adverse drug reactions are unpredictable and include various different skin conditions of varying degrees of severity. The most concerning are usually referred to as severe cutaneous adverse reactions (SCARs) and include acute generalized exanthematous pustulosis (AGEP), drug reaction with eosinophilia and systemic symptoms (DRESS), also known as drug-induced hypersensitivity syndrome (DiHS) or hypersensitivity syndrome (HSS), Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). All are delayed type IV hypersensitivity reactions in which a T-cell-mediated drug-specific immune response is responsible for causing the disease. Nonetheless, specific T-cell subpopulations develop in response to certain environmental conditions and produce cytokines that orchestrate the various phenotypes. Cytotoxic T lymphocytes (CTLs), T-helper type 1 (Th1), Th2, Th17, and regulatory T cells (Treg), among other T-cell subpopulations, participate in the development of SCAR phenotypes. Cell subpopulations belonging to the innate immune system, comprising natural killer cells, innate lymphoid cells, monocytes, macrophages and dendritic cells, can also participate in shaping specific immune responses in various clinical conditions. Additionally, tissue-resident cells, including keratinocytes, can contribute to epidermal damage by secreting chemokines that attract pro-inflammatory immunocytes. The final phenotypes in each clinical entity result from the complex interactions between a variety of cell lineages, their products, soluble mediators and genetic and environmental factors. Although the pathophysiology of these reactions is not fully understood, intensive research in recent years has led to major progress in our understanding of the contribution of certain cell types and soluble mediators to the variability of SCAR phenotypes.

Association of cutaneous adverse drug reactions due to antiepileptic drugs with HLA alleles in a North Indian population

PURPOSE

Aromatic antiepileptic drugs (AEDs) are frequently implicated in cutaneous adverse drug reactions (cADRs), a few of which are associated with certain human leukocyte antigen (HLA) alleles in some populations. We aimed to find HLA-associations with AED-related cADRs among North Indians.

METHODS

North Indian subjects with cADR due to an AED, and those who were AED-tolerant were recruited as cases and controls, respectively. Genotyping for HLA-A, B and DRB1 were performed. Statistical analysis to compare carrier-rates and allele-frequencies between cases and controls (and healthy population, where necessary), was done for HLA-alleles occurring more than twice in either group.

RESULTS

120 cases {11 - Lamotrigine (LTG), 14 -Valproic acid (VPA), 8 -Levetiracetam (LEV), 35 -Carbamazepine (CBZ) and 52 - Phenytoin (PHT)}, and 250 controls were recruited. Presence of HLA-A*31:01 and HLA-B*51:01 were found to increase the risk of Maculopapular exanthema (MPE) due to CBZ and PHT (OR = 6.38; 95% CI: 1.46-27.75; OR = 4.60; 95% CI: 1.54-13.72, respectively). Among the severe cADRs, HLA-B*57:01(OR = 11.00 95% CI: 1.41-85.81) and HLA-DRB1*07:01 (OR = 7.25; 95% CI: 1.09-48.18) were noted to be significantly associated with CBZ-induced Stevens Johnson Syndrome (SJS)/Toxic Epidermal Necrolysis (TEN); HLA-B *51:01 was associated with drug reaction eosinophilia and systemic symptoms (DRESS) caused by PHT (OR = 6.90; 95% CI: 1.38-34.29).

CONCLUSIONS

We found significant associations of some HLA alleles with specific cADRs to CBZ and PHT in North Indians, which may need to be tested before AED-initiation; only screening for HLA-B*15:02 may not help in this population.

An update on HLA alleles associated with adverse drug reactions

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

HLA-A*24:02 as a common risk factor for antiepileptic drug-induced cutaneous adverse reactions

Objective:

To investigate the involvement of human leukocyte antigen (HLA) loci in aromatic antiepileptic drug–induced cutaneous adverse reactions.

Methods:

A case-control study was performed to detect HLA loci involved in aromatic antiepileptic drug–induced Stevens-Johnson syndrome in a southern Han Chinese population. Between January 1, 2006, and December 31, 2015, 91 cases of Stevens-Johnson syndrome induced by aromatic antiepileptic drugs and 322 matched drug-tolerant controls were enrolled from 8 centers. Important genotypes were replicated in cases with maculopapular eruption and in the meta-analyses of data from other populations. Sequence-based typing determined the HLA-A, HLA-B, HLA-C, and HLA-DRB1 genotypes.

Results:

HLA-B*15:02 was confirmed as strongly associated with carbamazepine-induced Stevens-Johnson syndrome (p = 5.63 × 10⁻¹⁵). In addition, HLA-A*24:02 was associated significantly with Stevens-Johnson syndrome induced by the aromatic antiepileptic drugs as a group (p = 1.02 × 10⁻⁵) and by individual drugs (carbamazepine p = 0.015, lamotrigine p = 0.005, phenytoin p = 0.027). Logistic regression analysis revealed a multiplicative interaction between HLA-B*15:02 and HLA-A*24:02. Positivity for HLA-A*24:02 and/or HLA-B*15:02 showed a sensitivity of 72.5% and a specificity of 69.0%. The presence of HLA-A*24:02 in cases with maculopapular exanthema was also significantly higher than in controls (p = 0.023). Meta-analysis of data from Japan, Korea, Malaysia, Mexico, Norway, and China revealed a similar association.

Conclusions:

HLA-A*24:02 is a common genetic risk factor for cutaneous adverse reactions induced by aromatic antiepileptic drugs in the southern Han Chinese and possibly other ethnic populations. Pretreatment screening is recommended for people in southern China.

The HLA-A*31:01 allele: influence on carbamazepine treatment

Carbamazepine (CBZ) is an effective anticonvulsant that can sometimes cause hypersensitivity reactions that vary in frequency and severity. Strong associations have been reported between specific human leukocyte antigen (HLA) alleles and susceptibility to CBZ hypersensitivity reactions. Screening for HLA-B*15:02 is mandated in patients from South East Asia because of a strong association with Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). HLA-A*31:01 predisposes to multiple phenotypes of CBZ hypersensitivity including maculopapular exanthema, hypersensitivity syndrome, and SJS/TEN in a range of populations including Europeans, Japanese, South Koreans and Han Chinese, although the effect size varies between the different phenotypes and populations. Between 47 Caucasians and 67 Japanese patients would need to be tested for HLA-A*31:01 in order to avoid a single case of CBZ hypersensitivity. A cost-effectiveness study has demonstrated that HLA-A*31:01 screening would be cost-effective. Patient preference assessment has also revealed that patients prefer pharmacogenetic screening and prescription of alternative anticonvulsants compared to current standard of practice without pharmacogenetic testing. For patients who test positive for HLA-A*31:01, alternative treatments are available. When alternatives have failed or are unavailable, HLA-A*31:01 testing can alert clinicians to 1) patients who are at increased risk of CBZ hypersensitivity who can then be targeted for more intensive monitoring and 2) increase diagnostic certainty in cases where hypersensitivity has already occurred, so patients can be advised to avoid structurally related drugs in the future. On the basis of the current evidence, we would favor screening all patients for HLA-A*31:01 and HLA-B*15:02 prior to starting CBZ therapy.

Significant HLA class I type associations with aromatic antiepileptic drug (AED)-induced SJS/TEN are different from those found for the same AED-induced DRESS in the Spanish population

Aromatic antiepileptic drugs (AEDs) are among the drugs most frequently involved in severe cutaneous adverse reactions (SCARs), such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reactions with eosinophilia and systemic symptoms (DRESS). This study investigated the associations between the genetic polymorphisms of HLA class-I and AED-induced SCARs in the Spanish population. HLA class-I genotypes were determined in AED (phenytoin[PHT],lamotrigine[LTG],carbamazepine[CBZ],phenobarbital[PB])-induced SJS/TEN (n=15) or DRESS (n=12) cases included in the Spanish SCAR registry, PIELenRed. There were 3 control groups: (A)tolerant to a single AED, (B)tolerant to any AED, and (C)Spanish population controls. For SJS/TEN, concomitant HLA-A*02:01/Cw15:02 alleles were significantly associated with PHT-cases compared to control groups B and C [(B)odds ratio(OR):14.75, p=0.009;(C)OR:27.50, p<0.001], and were close to significance with respect to control group A (p=0.060). The genotype frequency of the HLA-B*38:01 was significantly associated with PHT-LTG-cases compared with the 3 groups of controls [(A)OR:12.86, p=0.012;(B)OR:13.81; p=0.002;(C)OR:14.35, p<0.001], and with LTG-cases [(A)OR:147.00, p=0.001;(B)OR:115.00, p<0.001;(C)OR:124.70, p<0.001]. We found the HLA-B*15:02 allele in a Spanish Romani patient with a CBZ-case. The HLA-A*11:01 was significantly associated with CBZ-cases [(A)OR:63.89, p=0.002;(B)OR:36.33, p=0.005;(C)OR:28.29, p=0.007]. For DRESS, the HLA-A*24:02 genotype frequency was statistically significant in the PHT-LTG-cases [(A)OR:22.56, p=0.003;(B)OR:23.50. p=0.001; (C)OR:33.25, p<0.001], and in the LTG-cases [(A),OR:49.00, p=0.015;(B)OR:27.77, p=0.005; (C)OR:34.53, p=0.002]. HLA-A*31:01 was significantly associated with the CBZ-cases [(A)OR:22.00, p=0.047;(B)OR:29.50, p=0.033;(C)OR:35.14, p=0.006]. In conclusion, we identified several significant genetic risk factors for the first time in the Spanish Caucasian population: HLA-A*02:01/Cw*15:02 combination as a risk factor for PHT-induced SJS/TEN, HLA-B*38:01 for LTG- and PHT- induced SJS/TEN, HLA-A*11:01 for CBZ-induced SJS/TEN, and HLA-A*24:02 for LTG- and PHT- induced DRESS. The strong association between HLA*31:01 and CBZ-DRESS in Europeans was confirmed in this study.

Desensitization to Oxcarbazepine: Long-Term Efficacy and Tolerability

BACKGROUND AND PURPOSE

Antiepileptic drug (AED)-associated cutaneous adverse drug reactions can lead to the discontinuation of medications. The aim of this study was to determine the long-term efficacy and safety of performing desensitization to oxcarbazepine.

METHODS

This study involved 20 patients who exhibited cutaneous adverse drug reactions associated with oxcarbazepine use between July 2009 and March 2016 at Samsung Medical Center. All of the participants had to discontinue oxcarbazepine despite presenting initially positive responses. Human leukocyte antigen genotyping was performed to detect the genetic predisposition to Stevens-Johnson syndrome. The desensitization to oxcarbazepine was performed with a starting dosage of 0.1 mg/day. Efficacy was evaluated by comparing the frequency of seizures before and at 1 and 3 years after desensitization. Adverse events occurring during desensitization and the retention rate after desensitization were also investigated.

RESULTS

Nineteen patients (95%) safely completed the desensitization protocol. One withdrew owing to emotional problems that appeared to be associated with oxcarbazepine. The follow-up period was 4.6±1.2 years (mean±SD), and oxcarbazepine was maintained for more than 3 years after desensitization in 15 patients (83.3%). The response rates were 84.2% and 77.8% at 1 and 3 years after desensitization, respectively. Eight patients remained seizure-free for 3 years, and two discontinued all AEDs. Transient adverse reactions such as mild rash and itching were reported by five patients during desensitization.

CONCLUSIONS

This study has demonstrated the long-term efficacy and safety of desensitization to oxcarbazepine in patients exhibiting cutaneous adverse drug reactions. This favorable outcome should encourage the implementation of desensitization in patients presenting with hypersensitivity to oxcarbazepine as an alternative strategy in clinical practice.