Carbamazepine and phenytoin induced Stevens-Johnson syndrome is associated with HLA-B*1502 allele in Thai population

Unraveling the genetic link: an umbrella review on HLA-B*15:02 and antiepileptic drug-induced Stevens-Johnson syndrome/toxic epidermal necrolysis

PURPOSE

This umbrella review was conducted to summarize the association between HLA*1502 allele with antiepileptic induced Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN).

METHODS

Pubmed, Scopus and EMBASE were searched for eligible reviews in May 2023. Two authors independently screened titles and abstracts and assessed full-text reviews for eligibility. The quality of meta-analyses and case-control studies was appraised with Assessing the Methodological Quality of Systematic Reviews 2 and Newcastle-Ottawa Scale, respectively. Narrative summaries of each antiepileptic drug were analyzed. Preestablished protocol was registered on the International Prospective Register of Systematic Reviews Registry(ID: CRD42023403957).

RESULTS

Included studies are systematic reviews, meta-analyses and case-control studies evaluating the association of HLA-B*1502 allele with the following antiepileptics. Seven meta-analyses for carbamazepine, three meta-analyses for lamotrigine (LTG), three case-control studies for oxcarbazepine, nine case-control studies for phenytoin and four case-control studies for phenobarbitone were included. The findings of this umbrella review suggest that there is a strong association between HLA-B-1502 with SJS/TEN for carbamazepine and oxcarbazepine and a milder association for lamotrigine and phenytoin.

CONCLUSION

In summary, although HLA-B*1502 is less likely to be associated with phenytoin or lamotrigine-induced SJS/TEN compared to carbamazepine-induced SJS/TEN, it is a significant risk factor that if carefully screened, could potentially reduce the development of SJS/TEN. In view of potential morbidity and mortality, HLA-B*1502 testing may be beneficial in patients who are initiating lamotrigine/phenytoin therapy. However, further studies are required to examine the association of other alleles with the development of SJS/TEN and to explore the possibility of genome-wide association studies before initiation of treatment.

Phenomic landscape and pharmacogenomic implications for HLA region in a Taiwan Han Chinese population

BACKGROUND

The human leukocyte antigen (HLA) genes, exhibiting significant genetic diversity, are associated with susceptibility to various clinical diseases and diverse in drug responses. High costs of HLA sequencing and the population-specific architecture of this genetic region necessitate the establishment of a population-specific HLA imputation reference panel. Moreover, there is a lack of understanding about the genetic and phenotypic landscape of HLA variations within the Taiwanese population.

METHODS

We created models for a Taiwanese-specific HLA imputation reference panel. These models were trained with the array genotype data and HLA sequencing data from 845 Taiwanese subjects. HLA imputation was applied for 59,448 Taiwanese subjects to characterize the HLA allele and haplotype frequencies. Additionally, a phenome-wide association study (PheWAS) was conducted to identify the phenotypes associated with HLA variations. The association of the biallelic HLA variants with the binary and quantitative traits were evaluated with additive logistic and linear regression models, respectively. Furthermore, an omnibus test with likelihood-ratio test was applied for each HLA amino acid position in the multiallelic HLA amino acid polymorphisms to compare the difference between a fitted model and a null model following a χ2 distribution of n-1 degree of freedom at a position with n residues. Finally, we estimated the prevalence of adverse drug reactions (ADR)-related HLA alleles in the Taiwanese population.

RESULTS

In this study, the reference panel models displayed remarkable accuracy, with averages of 99.3%, 98.9%, and 99.1% for 2-, 4-, 6-digit alleles of the eight classical HLA genes, respectively. For PheWAS, a total of 18,136 significant associations with HLA variants across 26 phenotypes are identified (p < 5×10-8), highlighting the pleiotropy feature of the HLA region. Among the independent signals, 15 are novel, including the association of HLA-B pos 138 variation with ankylosing spondylitis (AS), and rs9266290 and rs9266292 with allergy. Through an analysis spanning the entire HLA region, we identified clusters of phenotype correlations. Finally, the carriers of pharmacogenomic related HLA alleles, including HLA-C*01:02 (35.86%), HLA-B*58:01 (20.9%), and HLA-B*15:02 (8.38%), were characterized in the Taiwanese general population.

CONCLUSIONS

We successfully delivered the HLA imputation for 59,448 Taiwanese subjects and characterized the genetic and phenotypic landscapes of the HLA variations. In addition, we quantified the estimated prevalence of the ADR-related HLA alleles in the Taiwanese population. The developed HLA imputation reference panel could be used for estimation of population HLA allele frequencies, which can facilitate further studies in the role of HLA variants in a wider range of phenotypes in the population.

HLA-targeted sequencing reveals the pathogenic role of HLA-B*15:02/HLA-B*13:01 in albendazole-induced liver failure: a case report and a review of the literature

Drug-induced liver injury (DILI) is one of the serious adverse drug reactions (ADRs), which belongs to immune-mediated adverse drug reactions (IM-ADRs). As an essential health drug, albendazole has rarely been reported to cause serious liver damage. A young man in his 30 s developed severe jaundice, abnormal transaminases, and poor blood coagulation mechanism after taking albendazole, and eventually developed into severe liver failure. The patient was found heterozygous of HLA-B*15:02 and HLA-B*13:01 through HLA-targeted sequencing, which may have a pathogenic role in the disease. This case report summarizes his presentation, treatment, and prognosis. A useful summary of the diagnosis and associated genetic variant information is provided.

Risk-conferring HLA variants in an epilepsy cohort: benefits of multifaceted use of whole genome sequencing in clinical practice

BACKGROUND

Whole genome sequencing is increasingly used in healthcare, particularly for diagnostics. However, its clinically multifaceted potential for individually customised diagnostic and therapeutic care remains largely unexploited. We used existing whole genome sequencing data to screen for pharmacogenomic risk factors related to antiseizure medication-induced cutaneous adverse drug reactions (cADRs), such as human leucocyte antigen HLA-B*15:02, HLA-A*31:01 variants.

METHODS

Genotyping results, generated from the Genomics England UK 100 000 Genomes Project primarily for identification of disease-causing variants, were used to additionally screen for relevant HLA variants and other pharmacogenomic variants. Medical records were retrospectively reviewed for clinical and cADR phenotypes for HLA variant carriers. Descriptive statistics and the χ2 test were used to analyse phenotype/genotype data for HLA carriers and compare frequencies of additional pharmacogenomic variants between HLA carriers with and without cADRs, respectively.

RESULTS

1043 people with epilepsy were included. Four HLA-B*15:02 and 86 HLA-A*31:01 carriers were identified. One out of the four identified HLA-B*15:02 carriers had suffered antiseizure medication-induced cADRs; the point prevalence of cADRs was 16.9% for HLA-A*31:01 carriers of European origin (n=46) and 14.4% for HLA-A*31:01 carriers irrespective of ancestry (n=83).

CONCLUSIONS

Comprehensive utilisation of genetic data spreads beyond the search for causal variants alone and can be extended to additional clinical benefits such as identifying pharmacogenomic biomarkers, which can guide pharmacotherapy for genetically-susceptible individuals.

Impact on carbamazepine usage and cutaneous adverse reactions before and after the reimbursement of HLA-B*1502 genotyping in Taiwan, 2000-2017: A nationwide longitudinal study

OBJECTIVE

The HLA-B*1502 allele is strongly associated with carbamazepine (CBZ)-induced Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) in the Han Chinese population. This study investigated the impact of HLA-B*1502 screening on CBZ utilization and rates of severe cutaneous allergic reactions (SCARs) and SJS/TEN over time in Taiwan, where screening for HLA-B*1502 genotyping before prescribing CBZ was reimbursed in June 2010.

METHODS

Using the Taiwan National Health Insurance Research Database, we analyzed 13 277 457 episodes of seeking treatment for epilepsy or neuralgia between 2000 and 2017. Episodes were categorized into quarters based on treatment time. Propensity score-based stabilized weighting (PSSW) ensured well-balanced covariates. The difference in 3-month SCAR and SJS/TEN rates between phase 2 (2011-2017) and phase 1 (2000-2009) was examined using a one-sample Z-test. Pearson correlation coefficients assessed the association between screening rate, the number of CBZ users and nonusers, and SCAR and SJS/TEN rates after HLA-B*1502 genotyping.

RESULTS

CBZ prescriptions reduced from 7% (2000-2003) to 6% (2004-2010) and 4% (2011-2017). The screening rates of CBZ nonusers and CBZ users increased from 0%, .5% in 2011 to .8%, 16% in 2017, respectively. After PSSW, the mean 3-month SCAR incidence rates (per 10 000 episodes) significantly decreased from phase 1 to phase 2 for CBZ users (6.91 vs. 3.09, p < .0001) and nonusers (1.96 vs. 1.65, p < .0001). SJS/TEN incidence rates (per 10 000 episodes) significantly decreased from phase 1 to phase 2 for CBZ users (2.94 vs. 1.93, p < .0001) but not for nonusers (.71 vs. .74, p = .1492). In phase 2, SCAR incidence rates were significantly and negatively correlated with the screening rate for both CBZ users (r = -.38, p = .0342) and nonusers (r = -.80, p < .001). No significant correlation was found between SJS/TEN incidence rates and screening rates.

SIGNIFICANCE

Recognizing HLA-B*1502 allele and avoiding CBZ therapy in HLA-B*1502-positive patients is critical for preventing CBZ-induced severe adverse events.

New insights into the diagnosis and management of Stevens-Johnson syndrome and toxic epidermal necrolysis

PURPOSE OF REVIEW

Recent studies have been clarifying the pathogenesis and early diagnostic markers of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Additionally, the efficacy of tumor necrosis factor alpha inhibitors is attracting attention. This review provides) recent evidence for the diagnosis and management of SJS/TEN.

RECENT FINDINGS

Risk factors for the development of SJS/TEN have been identified, particularly the association between HLA and the onset of SJS/TEN with specific drugs, which has been intensively studied. Research on the pathogenesis of keratinocyte cell death in SJS/TEN has also progressed, revealing the involvement of necroptosis, an inflammatory cell death, in addition to apoptosis. Diagnostic biomarkers associated with these studies have also been identified.

SUMMARY

The pathogenesis of SJS/TEN remains unclear and effective therapeutic agents have not yet been established. As the involvement of innate immunity, such as monocytes and neutrophils, in addition to T cells, has become clear, a more complex pathogenesis is predicted. Further elucidation of the pathogenesis of SJS/TEN is expected to lead to the development of new diagnostic and therapeutic agents.

Severe ocular complications of SJS/TEN and associations among pre-onset, acute, and chronic factors: a report from the international ophthalmology collaborative group

We formed an international research collaboration that included Japan, South Korea, Brazil, Thailand, Taiwan, the UK, and the US (682 patients from 13 hospitals between 2005 and 2020), to better evaluate the role of race, ethnicity, and other risk factors in the pathophysiology of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Ophthalmologists often see SJS/TEN patients with severe ocular complications (SOC; frequency 50% SJS/TEN patients) when the patients are referred to them in the chronic stage after the acute stage has passed. Global data were collected using a Clinical Report Form, capturing pre-onset factors, as well as acute and chronic ocular findings. Key conclusions of this retrospective observational cohort study were as follows: (1) Ingestion of cold medications [acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs)] was significantly and positively correlated with trichiasis, symblepharon, and/or conjunctivalization of the cornea in the chronic stage; (2) common cold symptoms prior to onset of SJS/TEN were significantly and positively correlated with acute conjunctivitis and ocular surface erosions in the acute stage and with trichiasis and symblepharon and/or conjunctivalization of the cornea in the chronic stage; (3) patients with SJS/TEN who presented with SOC tended to be female; (4) patients less than 30 years of age are more likely to develop SOC in the acute and chronic stages of SJS/TEN; (5) patients with acute severe conjunctivitis with ocular surface erosion and pseudomembrane formation in the acute stage are more likely to develop ocular sequelae in the chronic stage; and (6) onychopathy in the acute stage was positively correlated with ocular sequelae in the chronic stage. Our findings show that the ingestion of cold medications, common cold symptoms prior to the onset of SJS/TEN, and a young age might strongly contribute to developing the SOC of SJS/TEN.

Avoidance of cutaneous adverse drug reactions induced by antiepileptic drugs based on pharmacogenomics

Pharmacogenomics (PGx) is a research area aimed at identifying genetic factors that are associated with drug responses, including drug efficacy, adverse drug reactions, and the appropriate drug dosage on a case-to-case basis. To promote the clinical implementation of PGx testing, which is currently of limited use in clinical practice, recent research has focused on providing reliable evidence for its clinical utility. In neurology, psychiatry, and neurosurgery, several human leukocyte antigen (HLA) alleles have been reportedly associated with cutaneous adverse drug reactions (cADRs) induced by antiepileptic drugs, which significantly carry the risk of developing cADRs. Prior to using antiepileptic drugs such as carbamazepine and lamotrigine, which are prone to cause severe cADRs, preemptive HLA genetic testing and therapeutic interventions such as drug selection and dosage adjustment based on the results of the tests can reduce the incidence of cADRs in the population before the initiation of treatment.

Updates on the immunopathology and genomics of severe cutaneous adverse drug reactions

Severe cutaneous adverse reactions (SCARs) such as Stevens-Johnson syndrome, toxic epidermal necrolysis (SJS/TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS)/drug-induced hypersensitivity syndrome (DIHS) cause significant morbidity and mortality and impede new drug development. HLA class I associations with SJS/TEN and drug reaction with eosinophilia and systemic symptoms/drug-induced hypersensitivity syndrome have aided preventive efforts and provided insights into immunopathogenesis. In SJS/TEN, HLA class I-restricted oligoclonal CD8+ T-cell responses occur at the tissue level. However, specific HLA risk allele(s) and antigens driving this response have not been identified for most drugs. HLA risk alleles also have incomplete positive and negative predictive values, making truly comprehensive screening currently challenging. Although, there have been key paradigm shifts in knowledge regarding drug hypersensitivity, there are still many open and unanswered questions about SCAR immunopathogenesis, as well as genetic and environmental risk. In addition to understanding the cellular and molecular basis of SCAR at the single-cell level, identification of the MHC-restricted drug-reactive self- or viral peptides driving the hypersensitivity reaction will also be critical to advancing premarketing strategies to predict risk at an individual and drug level. This will also enable identification of biologic markers for earlier diagnosis and accurate prognosis, as well as drug causality and targeted therapeutics.

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS): Focus on the Pathophysiological and Diagnostic Role of Viruses

Drug reaction with eosinophilia and systemic symptoms (DRESS) is a heterogeneous, multiorgan and potentially life-threatening drug-hypersensitivity reaction (DHR) that occurs several days or weeks after drug initiation or discontinuation. DHRs constitute an emerging issue for public health, due to population aging, growing multi-organ morbidity, and subsequent enhanced drug prescriptions. DRESS has more consistently been associated with anticonvulsants, allopurinol and antibiotics, such as sulphonamides and vancomycin, although new drugs are increasingly reported as culprit agents. Reactivation of latent infectious agents such as viruses (especially Herpesviridae) plays a key role in prompting and sustaining aberrant T-cell and eosinophil responses to drugs and pathogens, ultimately causing organ damage. However, the boundaries of the impact of viral agents in the pathophysiology of DRESS are still ill-defined. Along with growing awareness of the multifaceted aspects of immune perturbation caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the ongoing SARS-CoV-2-related disease (COVID-19) pandemic, novel interest has been sparked towards DRESS and the potential interactions among antiviral and anti-drug inflammatory responses. In this review, we summarised the most recent evidence on pathophysiological mechanisms, diagnostic approaches, and clinical management of DRESS with the aim of increasing awareness on this syndrome and possibly suggesting clues for future research in this field.

Delayed Drug Hypersensitivity Reactions: Molecular Recognition, Genetic Susceptibility, and Immune Mediators

Drug hypersensitivity reactions are classified into immediate and delayed types, according to the onset time. In contrast to the immediate type, delayed drug hypersensitivity mainly involves T lymphocyte recognition of the drug antigens and cell activation. The clinical presentations of such hypersensitivity are various and range from mild reactions (e.g., maculopapular exanthema (MPE) and fixed drug eruption (FDE)), to drug-induced liver injury (DILI) and severe cutaneous adverse reactions (SCARs) (e.g., Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP)). The common culprits of delayed drug hypersensitivity include anti-epileptics, antibiotics, anti-gout agents, anti-viral drugs, etc. Delayed drug hypersensitivity is proposed to be initiated by different models of molecular recognition, composed of drug/metabolite antigen and endogenous peptide, HLA presentation, and T cell receptor (TCR) interaction. Increasing the genetic variants of HLA loci and drug metabolic enzymes has been identified to be responsible for delayed drug hypersensitivity. Furthermore, preferential TCR clonotypes, and the activation of cytotoxic proteins/cytokines/chemokines, are also involved in the pathogenesis of delayed drug hypersensitivity. This review provides a summary of the current understanding of the molecular recognition, genetic susceptibility, and immune mediators of delayed drug hypersensitivity.

Associations of HLA-A and HLA-B with vancomycin-induced drug reaction with eosinophilia and systemic symptoms in the Han-Chinese population

Vancomycin is a commonly used antibiotic; however, it can cause life-threatening severe cutaneous adverse reactions, such as drug reaction with eosinophilia and systemic symptoms (DRESS). A previous study has reported a strong association between HLA-A*32:01 and vancomycin-induced DRESS in European ethnicity. Herein, we aim to investigate the genetic predisposition of vancomycin-induced DRESS in the Han-Chinese population. In this study, we enrolled a total of 26 patients with vancomycin-induced DRESS, 1,616 general population controls, and 51 subjects tolerant to vancomycin. In vitro granulysin-based lymphocyte activation tests (LAT) were conducted among 6 vancomycin-induced DRESS patients who were concomitantly receiving other medicines. HLA-A and HLA-B genotypes were determined by sequencing-based typing. Our results found that vancomycin-induced DRESS was associated with HLA-A*32:01 [odds ratio (OR) = 7.8, 95% confidence interval (CI) = 1.7-35.8; p-value = 0.035], HLA-B*07:05 (OR = 32.3, 95% CI = 2.8-367.7; p-value = 0.047), HLA-B*40:06 (OR = 4.7, 95% CI = 1.3-16.1; p-value = 0.036) and HLA-B*67:01 (OR = 44.8, 95% CI = 7.2-280.4; p-value = 0.002) when comparing the vancomycin-induced DRESS patients with the general population controls. LAT results showed that granulysin significantly increased in the vancomycin-induced DRESS patients upon vancomycin stimulation (4.7 ± 3.7 fold increased), but not upon other co-medicines. This study identified that, in addition to HLA-A*32:01, HLA-B*07:05, HLA-B*40:06, and HLA-B*67:01 were also genetic markers for vancomycin-induced DRESS in the Han-Chinese population. Associations of ethnic variances in HLA with vancomycin-DRESS were observed.

Genotyping for HLA risk alleles versus patch tests to diagnose anti-seizure medication induced cutaneous adverse drug reactions

Aim: To provide a comparison of genotyping for HLA risk alleles versus patch testing to determine which of these two tests is a better diagnostic tool for cutaneous hypersensitivity reactions caused by anti-seizure medication.

Methods: A literature study was performed in PubMed to assess the sensitivity and specificity of HLA genotyping and patch tests for identifying anti-seizure medication induced cutaneous hypersensitivity reactions.

Results: This study shows that HLA-B*15:02 genotyping shows high sensitivity for carbamazepine-induced SJS/TEN, especially in Han Chinese and Southeast Asian patients (66.7–100.0%) whereas the sensitivity of patch tests (0.0–62,5%), HLA-A*31:01 (0–50%) and HLA-B*15:11 (18.2–42.9%) are lower. On the contrary, for carbamazepine and phenytoin induced DRESS, patch tests (respectively 70.0–88.9% and 14.3–70.0%) show higher sensitivity than HLA tests (0–66.7% and 0–12.7%). Also for lamotrigine-induced DRESS patch tests perform better than HLA-B*15:02 (33.3–40.0 versus 0%). For anti-seizure medication induced MPE and for oxcarbazepine-induced SCARs more studies are needed.

Conclusion: Use of HLA-B genotyping may aid clinicians in the diagnosis of carbamazepine, phenytoin, lamotrigine and oxcarbazepine induced SJS/TEN, particularly in Han Chinese and Southeast Asian patients. On the other hand, patch tests seem to perform better in the diagnosis of carbamazepine and phenytoin induced DRESS.

Review of culprit drugs associated with patients admitted to the burn unit with the diagnosis of Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis Syndrome

PURPOSE

Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis Syndrome (TENS) are severe and potentially lethal adverse drug reactions characterized by acute inflammation of the skin, mucous membranes, and ocular surface that typically occurs within weeks of a culprit drug ingestion. The purpose of this study is to report a retrospective trend analysis of SJS spectrum diagnoses and associated culprit drugs in patients admitted to the Loyola University Medical Center (LUMC) Burn Unit, the major referral center in the Chicagoland region for patients with SJS disease spectrum.

METHODS

The electronic medical records (EMR) of 163 patients with a diagnosis of SJS/TENS admitted to the LUMC Burn Unit from 2000 to 2019 were reviewed. Clinical data in addition to the well-established algorithm of drug causality for epidermal necrolysis (ALDEN) allowed us to identify the single most probable culprit drug in 131 cases.

RESULTS

From 2000 to 2019, the most common spectrum classification was TENS (48.1%), followed by SJS (33.6%) and SJS-TEN Overlap Syndrome (18.3%). Anticonvulsants were found to be the most probable culprit class in 30% of cases followed by Trimethoprim-Sulfamethoxazole in 19% of cases. Beta-lactams were the most probable culprit class in 11% of cases while NSAIDs and allopurinol were each the most probable culprit class/drug in 8.4% of cases.

CONCLUSIONS

This is one of the largest single center series of SJS/TENS cases in the United States. Further study into culprit drug distribution by region as well as continuous monitoring of trends is crucial in order to advise prescribing practices.

Development of label-free electrochemical impedance spectroscopy for the detection of HLA-B*15:02 and HLA-B*15:21 for the prevention of carbamazepine-induced Stevens-Johnson syndrome

BACKGROUND

Carbamazepine (CBZ) is an FDA-approved anticonvulsant that is widely used to treat epilepsy, bipolar disorder, trigeminal neuralgia and chronic pain. Several studies have reported a strong association between HLA-B*15:02 and carbamazepine-induced Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN). However, the HLA-B75 serotype (HLA-B*15:02, HLA-B*15:08, HLA-B*15:11 and HLA-B*15:21) has been found in patients with carbamazepine-induced SJS/TEN.

METHODS

This study aimed to develop label-free electrochemical impedance spectroscopy (EIS) for the detection of HLA-B*15:02 and HLA-B*15:21 after PCR-SSP amplification. A total of 208 DNA samples were tested. The impedance was measured and compared to standard gel electrophoresis.

RESULTS

The developed label-free EIS identified HLA-B*15:02 and HLA-B*15:21 alleles with 100% sensitivity (95% CI: 86.773%-100.000%) and 95.05% specificity (95% CI: 90.821%-97.714%), comparable to commercial DMSc 15:02 detection kits.

CONCLUSIONS

We successfully developed a novel PCR-SSP associated with signal impedance changes to detect the HLA-B*15:02 allele and HLA-B*15:21 without downstream amplicon size analysis that is suitable for screening individuals before indication of CBZ therapy.

Role of human leukocyte antigen in anti-epileptic drugs-induced Stevens-Johnson Syndrome/toxic epidermal necrolysis: A meta-analysis

PURPOSE

Antiepileptic drugs (AEDs) are extensively used to manage epilepsy and other comorbidities associated with seizures. Human Leukocyte Antigen (HLA) has a strong association with AED-induced severe cutaneous adverse drug reactions.

OBJECTIVE

We aimed to perform a systematic review and meta-analysis to identify, critically evaluate, and synthesize the best possible evidence on HLA-associated AED-induced Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN).

METHODS

MEDLINE/PubMed, Scopus, and the Cochrane Library were searched for literature from inception up to July 2022. We included case control studies analyzing association between HLA and AED-induced SJS/TEN. We assessed the studies' risk of bias in using Quality of genetic studies (Q-genie) tool. Outcomes focused on association (risk) between HLA and AED-induced SJS/TEN. The estimated risk was presented in the form of odds ratio (OR).

RESULTS

We included 37 studies (51,422 participants; 7027 cases and 44,395 controls). There was a significantly higher risk of Carbamazepine-induced SJS/TEN with HLA-A (OR: 1.50; 95% CI: 1.03 to 2.17), HLA-B (OR: 1.94; 95% CI: 1.45 to 2.58), HLA-C (OR: 7.83; 95% CI: 4.72 to 12.98), and HLA-DRB1 (OR: 2.82; 95% CI: 1.94 to 4.12). Lamotrigine-induced SJS/TEN posed a higher risk with HLA-A (OR: 2.38; 95% CI: 1.26 to 4.46) and HLA-B (OR: 2.79; 95% CI: 1.75 to 4.46). Phenytoin-induced SJS/TEN showed a higher risk with HLA-A (OR: 3.47; 95% CI: 2.17 to 5.56), HLA-B (OR: 1.72; 95% CI: 1.38 to 2.15), and HLA-C (OR: 2.92; 95% CI: 1.77 to 4.83). Phenobarbital-induced SJS/TEN had a higher risk with HLA-A (OR: 6.98; 95% CI: 1.81 to 26.84), HLA-B (OR: 2.40; 95% CI: 1.39 to 4.17), and HLA-C (OR: 3.37; 95% CI: 1.03 to 11.01). Zonisamide-induced SJS/TEN was significantly associated with HLA-A*02:07 (OR: 9.77; 95% CI: 3.07 to 31.1), HLA-B*46:01 (OR: 6.73; 95% CI: 2.12 to 21.36), and HLA-DRB1×08:03 (OR: 3.78; 95% CI: 1.20 to 11.97). All other alleles of HLA were observed to have a non-significant association with AED-induced SJS/TEN. All included studies were of good quality, with a score of >50 and a mean score of 54.96 out of 77.

CONCLUSION

Our study showed a significant association between few variants of HLA alleles and AED-induced SJS/TEN. Evidences from our study could help in population-based studies and in implementation of individualized treatment regimens. These findings could be part of translational research helping in precision therapy.

Etoricoxib Induced Toxic Epidermal Necrolysis in a case of Systemic Lupus Erythematosus: A Case Report

Toxic epidermal necrolysis is a potentially life-threatening dermatological condition whose pathogenesis and exact treatment are not yet known. Drugs like anticonvulsants, allopurinol and non-steroidal anti-inflammatory drugs like etoricoxib, a selective cyclo-oxygenase-2 inhibitor prescribed for pain management are associated with a high risk of toxic epidermal necrolysis. It is also associated with immunodeficiency and dysregulated immune reactions like systemic lupus erythematosus, an autoimmune disease in which organs and cells undergo damage initially mediated by tissue binding auto-antibodies and immune complexes. Here, a 34 year old lady was presented in emergency with multiple maculopapular rashes over the neck and trunk region after treatment with etoricoxib for osteoarthritis of the left foot.

Implementation of HLA-B*15:02 Genotyping as Standard-of-Care for Reducing Carbamazepine/Oxcarbazepine Induced Cutaneous Adverse Drug Reactions in Thailand

Objective: This study aimed to investigate the clinical impact of HLA-B*15:02 pharmacogenomics (PGx) testing before carbamazepine (CBZ)/oxcarbazepine (OXC) prescriptions and to determine whether this PGx testing was associated with the reduction of CBZ/OXC-induced cutaneous adverse drug reactions (CADRs) in Thailand.

Methods: This retrospective observational cohort study was conducted by obtaining relevant HLA-B*15:02 PGx-testing and clinical data from electronic medical records during 2011–2020. 384 patient data were included in this study to investigate the clinical decision on CBZ/OXC usage before and after the HLA-B*15:02 PGx testing, and 1,539 patient data were included in this study to demonstrate the incidence of CBZ/OXC-induced SCARs and SJS between HLA-B*15:02 tested and non-tested patients. To analyze and summarize the results, descriptive statistics were employed, and Fisher exact test was used to compare the clinical difference between the HLA-B*15:02 positive and negative groups and to compare the differences of SCARs incidence.

Results: 384 patients were included in this study as per the inclusion criteria. Of these, 70 patients carried HLA-B*15:02, of which 63 and 65 patients were not prescribed with CBZ/OXC before and after the availability of genotyping results, respectively. In the remaining HLA-B*15:02 non-carriers, 48, and 189 patients were prescribed CBZ/OXC before and after genotyping results were available, respectively. The findings of this study showed that the incidence of SCARs of CBZ/OXC was significantly lower (p &lt; 0.001) in the HLA-B*15:02 screening arm than in the non-screening arm.

Conclusion:HLA-B pharmacogenetics testing influenced the selection of appropriate AEDs. The presence of mild rash in the HLA-B*15:02 negative group indicates that other genetic biomarker (HLA-A*31:01) and/or non-genetic variables are involved in CBZ/OXC-induced CADRs, emphasizing that CBZ/OXC prescriptions necessitate CADR monitoring. The hospital policy and clinical decision support (CDS) alert system is essential to overcome the barriers associated with the utilization of PGx guidelines into clinical practice.

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.

Exome sequencing allows detection of relevant pharmacogenetic variants in epileptic patients

Beyond the identification of causal genetic variants in the diagnosis of Mendelian disorders, exome sequencing can detect numerous variants with potential relevance for clinical care. Clinical interventions can thus be conducted to improve future health outcomes for patients and their at-risk relatives, such as predicting late-onset genetic disorders accessible to prevention, treatment or identifying differential drug efficacy and safety. To evaluate the interest of such pharmacogenetic information, we designed an "in house" pipeline to determine the status of 122 PharmGKB (Pharmacogenomics Knowledgebase) variant-drug combinations in 31 genes. This pipeline was applied to a cohort of 90 epileptic patients who had previously an exome sequencing (ES) analysis, to determine the frequency of pharmacogenetic variants. We performed a retrospective analysis of drug plasma concentrations and treatment efficacy in patients bearing at least one relevant PharmGKB variant. For PharmGKB level 1A variants, CYP2C9 status for phenytoin prescription was the only relevant information. Nineteen patients were treated with phenytoin, among phenytoin-treated patients, none were poor metabolizers and four were intermediate metabolizers. While being treated with a standard protocol (10-23 mg/kg/30 min loading dose followed by 5 mg/kg/8 h maintenance dose), all identified intermediate metabolizers had toxic plasma concentrations (20 mg/L). In epileptic patients, pangenomic sequencing can provide information about common pharmacogenetic variants likely to be useful to guide therapeutic drug monitoring, and in the case of phenytoin, to prevent clinical toxicity caused by high plasma levels.

An Updated Review of Genetic Associations With Severe Adverse Drug Reactions: Translation and Implementation of Pharmacogenomic Testing in Clinical Practice

Adverse drug reactions (ADR) remain the major problems in healthcare. Most severe ADR are unpredictable, dose-independent and termed as type B idiosyncratic reactions. Recent pharmacogenomic studies have demonstrated the strong associations between severe ADR and genetic markers, including specific HLA alleles (e.g., HLA-B*15:02/HLA-B*57:01/HLA-A*31:01 for carbamazepine-induced severe cutaneous adverse drug reactions [SCAR], HLA-B*58:01 for allopurinol-SCAR, HLA-B*57:01 for abacavir-hypersensitivity, HLA-B*13:01 for dapsone/co-trimoxazole-induced SCAR, and HLA-A*33:01 for terbinafine-induced liver injury), drug metabolism enzymes (such as CYP2C9*3 for phenytoin-induced SCAR and missense variant of TPMT/NUDT15 for thiopurine-induced leukopenia), drug transporters (e.g., SLCO1B1 polymorphism for statin-induced myopathy), and T cell receptors (Sulfanilamide binding into the CDR3/Vα of the TCR 1.3). This mini review article aims to summarize the current knowledge of pharmacogenomics of severe ADR, and the potentially clinical use of these genetic markers for avoidance of ADR.

Drug-Induced Severe Cutaneous Adverse Reactions: Insights Into Clinical Presentation, Immunopathogenesis, Diagnostic Methods, Treatment, and Pharmacogenomics

SCARs are rare and life-threatening hypersensitivity reactions. In general, the increased duration of hospital stays and the associated cost burden are common issues, and in the worst-case scenario, they can result in mortality. SCARs are delayed T cell-mediated hypersensitivity reactions. Recovery can take from 2 weeks to many months after dechallenging the culprit drugs. Genetic polymorphism of the HLA genes may change the selection and presentation of antigens, allowing toxic drug metabolites to initiate immunological reactions. However, each SCARs has a different onset latency period, clinical features, or morphological pattern. This explains that, other than HLA mutations, other immuno-pathogenesis may be involved in drug-induced severe cutaneous reactions. This review will discuss the clinical morphology of various SCARs, various immune pathogenesis models, diagnostic criteria, treatments, the association of various drug-induced reactions and susceptible alleles in different populations, and the successful implementation of pharmacogenomics in Thailand for the prevention of SCARs.

Drug-Induced Hypersensitivity Syndrome (DIHS)/Drug Reaction With Eosinophilia and Systemic Symptoms (DRESS): Clinical Features and Pathogenesis

Drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DIHS/DRESS) is one example of a severe delayed T-cell-mediated adverse drug reaction. DIHS/DRESS presents with fever, widespread rash and facial edema, organ involvement, and hematological abnormalities, including eosinophilia and atypical lymphocytosis. DIHS/DRESS is associated with relapse 2 to 4 weeks after acute symptoms, often coinciding with reactivation of prevalent chronic persistent human herpesviruses such as human herpesvirus 6, EBV, and cytomegalovirus. The mortality of DIHS/DRESS is up to 10% and often related to unrecognized myocarditis and cytomegalovirus complications, with longer-term consequences that contribute to morbidity including autoimmune diseases such as thyroiditis. It is essential that all potential drug causes, including all new drugs introduced within the 8 weeks preceding onset of DIHS/DRESS symptoms, are identified. All potential drug culprits, as well as drugs that are closely related structurally to the culprit drug, should be avoided in the future. Systemic corticosteroids have remained the mainstay for the treatment of DIHS/DRESS with internal organ involvement. Steroid-sparing agents, such as cyclosporine, mycophenolate mofetil, and monthly intravenous immune globulin, have been successfully used for treatment, and careful follow-up for cytomegalovirus reactivation is recommended. Strong associations between HLA class I alleles and DIHS/DRESS predisposition include HLA-B∗13:01 and dapsone, HLA-B∗58:01 and allopurinol, and HLA-B∗32:01 and vancomycin. These have opened a pathway for prevention, risk stratification, and earlier diagnosis. Single-cell sequencing and other studies of immunopathogenesis promise to identify targeted treatment approaches.

Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis in the Era of Systems Medicine

Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are severe mucocutaneous bullous disorders characterized by widespread skin and mucosal necrosis and detachment, which are most commonly triggered by medications. Despite their rarity, these severe cutaneous adverse drug reactions will result in high mortality and morbidity as well as long-term sequela. The immunopathologic mechanisms is mainly cell-mediated cytotoxic reaction against keratinocytes leading to massive skin necrolysis. Subsequent studies have demonstrated that immune synapse composed of cytotoxic T cells with drug-specific human leukocyte antigen (HLA) class I restriction and T cell receptors (TCR) repertoire is the key pathogenic for SJS/TEN. Various cytotoxic proteins and cytokines such as soluble granulysin, perforin, granzyme B, interleukin-15, Fas ligand, interferon-γ, tumor necrosis factor-α have been as mediators involved in the pathogenesis of SJS/TEN. Early recognition and immediate withdrawal of causative agents, and critical multidisciplinary supportive care are key management of SJS/TEN. To date, there is yet to be a sufficient consensus or recommendation for the immunomodulants of the treatment in SJS/TEN. Systemic corticosteroids remain one of the most common treatment options for SJS/TEN, though the efficacy remain uncertain. Currently, there is increasing evidence showing that cyclosporine and TNF-α inhibitors decrease the mortality of SJS/TEN. Further multicenter double-blinded, randomized, placebo-controlled trials are required to confirm the efficacy and safety.

The association between HLA-B*15:02 and phenytoin-induced severe cutaneous adverse reactions: a meta-analysis

Aim: Phenytoin (PHT) is a common anticonvulsant agent known for inducing severe cutaneous adverse reactions (SCARs). HLA-B*15:02 as a risk factor of PHT-induced SCARs was reported in numerous studies with inconsistent results. This meta-analysis aimed to establish pooling evidence of this association. Materials & methods: Pooled odds ratios (ORs) with 95% CIs were estimated using a random-effects model. Results: A total of 11 studies on 1389 patients, were included for the analyses. There was a significant association between HLA-B*15:02 and PHT-induced SCAR (pooled OR = 2.29, 95% CI: 1.25-4.19, p = 0.008). Furthermore, there was a significant association regarding Stevens-Johnson syndrome/toxic epidermal necrolysis (OR = 3.63, 95% CI: 2.15-6.13, p < 0.001) but no association regarding drug reaction with eosinophilia and systemic symptom. Conclusion: The results supported the recommendations of HLA-B*15:02 screening before treatment with PHT.

Pharmacogenetics of Drug-Resistant Epilepsy (Review of Literature)

Pharmacogenomic studies in epilepsy are justified by the high prevalence rate of this disease and the high cost of its treatment, frequent drug resistance, different response to the drug, the possibility of using reliable methods to assess the control of seizures and side effects of antiepileptic drugs. Candidate genes encode proteins involved in pharmacokinetic processes (drug transporters, metabolizing enzymes), pharmacodynamic processes (receptors, ion channels, enzymes, regulatory proteins, secondary messengers) and drug hypersensitivity (immune factors). This article provides an overview of the literature on the influence of genetic factors on treatment in epilepsy.

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

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

Association between the HLA-B*1502 gene and mild maculopapular exanthema induced by antiepileptic drugs in Northwest China

BACKGROUND

The relationship between the HLA-B*1502 gene and maculopapular exanthema (MPE) induced by antiepileptic drugs (AEDs) has not yet been elucidated. In this study, we investigated the association between AED-induced MPE (AED-MPE) and the HLA-B*1502 gene in patients in Northwest China.

METHODS

We enrolled 165 subjects including nine patients with AED-MPE and 156 AED-tolerant patients as controls. HLA-B*1502 gene polymorphism was detected using digital fluorescence molecular hybridization (DFMH). The results of HLA genotyping were expressed as positive or negative for the HLA-B*1502 allele. An analysis of AED-MPE risk factors was performed using binary logistic regression, and differences in genotype frequencies between groups were assessed with the continuity correction chi-square test.

RESULTS

We found that the HLA-B*1502 gene was a risk factor for AED-MPE (P = 0.028). The incidence of MPE induced by the two types of AEDs was different, and the incidence of aromatic AEDs use was higher that of non-aromatic AEDs use (P = 0.025). The comparison of the gene frequencies of the HLA-B*1502 allele between the two groups taking aromatic AEDs was also statistically significant (P = 0.045). However, there were no significant differences in terms of age, gender, ethnicity, or region in patients with MPE induced by AEDs. In addition, no association between the HLA-B1502 allele and CBZ- or OXC-induced MPE was found.

CONCLUSIONS

In northwestern China, the HLA-B*1502 allele was associated with aromatic AED-MPE. Since MPE can develop into Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN), the HLA-B*1502 gene should be evaluated before administering AEDs.

HLA-associated adverse drug reactions - scoping review

Alleles of the human leukocyte antigen (HLA) system have been associated with the occurrence of idiosyncratic adverse drug reactions (ADRs). Accordingly, it is assumed that pre-emptive testing for the presence of certain HLA alleles (HLA-typing) could prevent these ADRs in carriers. In order to perceive the current evidence for HLA-associated ADRs, we conducted a scoping review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The literature search on PubMed and on Embase was carried out on the July 8 and 9, 2020, respectively. To be included in the scoping review, the studies had to investigate an association of any HLA-associated ADR with any small molecule approved and available on the Swiss market. We considered English and German primary literature published since 2002. A total of 149 studies were included, whereof most were retrospective, whereas one was a prospective randomized controlled trial. The majority of the studies (n = 33) described the association of HLA-B*15:02 with carbamazepine. It was not possible to directly compare the studies, as they were too heterogeneous in terms of the ADR definition, the HLA alleles, the number of participants, and the study types. Therefore, we summarized the results in a descriptive manner. Even if an interpretation of the outcomes remains open, the descriptive overview revealed the prevailing complexity and uncertainty in the field. For the future, consistent definitions on the different phenotypes need to be established and applied and the reporting of association studies should follow a harmonized structure.

Cost-effectiveness analysis of genotyping for HLA-B*15:02 in Indonesian patients with epilepsy using a generic model

Carbamazepine (CBZ)-induced Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are strongly associated with the HLA-B*15:02 allele. Screening HLA-B*15:02 before CBZ administration might prevent CBZ-induced SJS/TEN by enabling clinicians to prescribe alternative therapy for positive patients. Similar to other Southeastern Asian countries, HLA-B*15:02 is highly prevalent in Indonesia. Therefore, we assessed the economic value of HLA-B*15:02 screening before CBZ prescription to patients with epilepsy in Indonesia. A generic cost-effectiveness model and decision support tool, developed to enable users to perform an initial cost-effectiveness analysis from a healthcare provider/payer perspective, were used to assess the value of HLA-B*15:02 genotyping. The incremental cost-effectiveness ratio of adopting universal HLA-B*15:02 screening was 656,444,671 Indonesian Rupiah (IDR)/quality-adjusted life year (QALY) gained for patients compared with 2,634,975,574 IDR/QALY gained for providing valproic acid (alternative drug) without screening. Thus, neither HLA-B*15:02 screening nor substitution with VPA meets the Indonesian threshold for cost effectiveness. However, the improved outcomes with this test in other Asian countries may inform the desirability of implementation in Indonesia even with suboptimal cost-effectiveness.

Association of HLA-B*51:01, HLA-B*55:01, CYP2C9*3, and Phenytoin-Induced Cutaneous Adverse Drug Reactions in the South Indian Tamil Population

Phenytoin (PHT) is one of the most commonly reported aromatic anti-epileptic drugs (AEDs) to cause cutaneous adverse reactions (CADRs), particularly severe cutaneous adverse reactions (SCARs). Although human leukocyte antigen (HLA)-B*15:02 is associated with PHT-induced Steven Johnson syndrome/toxic epidermal necrosis (SJS/TEN) in East Asians, the association is much weaker than it is reported for carbamazepine (CBZ). In this study, we investigated the association of pharmacogenetic variants of the HLA B gene and CYP2C9*3 with PHT-CADRs in South Indian epileptic patients. This prospective case-controlled study included 25 PHT-induced CADRs, 30 phenytoin-tolerant patients, and 463 (HLA-B) and 82 (CYP2C9*3) normal-controls from previous studies included for the case and normal-control comparison. Six SCARs cases and 19 mild-moderate reactions were observed among the 25 cases. Pooled data analysis was performed for the HLA B*51:01 and PHT-CADRs associations. The Fisher exact test and multivariate binary logistic regression analysis were used to identify the susceptible alleles associated with PHT-CADRs. Multivariate analysis showed that CYP2C9*3 was significantly associated with overall PHT-CADRs (OR = 12.00, 95% CI 2.759–84.87, p = 003). In subgroup analysis, CYP2C9*3 and HLA B*55:01 were found to be associated with PHT-SCARs (OR = 12.45, 95% CI 1.138–136.2, p = 0.003) and PHT-maculopapular exanthema (MPE) (OR = 4.041, 95% CI 1.125–15.67, p = 0.035), respectively. Pooled data analysis has confirmed the association between HLA B*51:01/PHT-SCARs (OR = 6.273, 95% CI 2.24–16.69, p = <0.001) and HLA B*51:01/PHT-overall CADRs (OR = 2.323, 95% CI 1.22–5.899, p = 0.037). In this study, neither the case nor the control groups had any patients with HLA B*15:02. The risk variables for PHT-SCARs, PHT-overall CADRs, and PHT-MPE were found to be HLA B*51:01, CYP2C9*3, and HLA B*55:01, respectively. These alleles were identified as the risk factors for the first time in the South Indian Tamil population for PHT-CADRs. Further investigation is warranted to establish the clinical relevance of these alleles in this population with larger sample size.

Genetics of Severe Cutaneous Adverse Reactions

Severe cutaneous adverse reactions (SCARs) including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug rash with eosinophilia and systemic symptoms (DRESS) are T cells-mediated life-threatening immune reactions, most commonly induced by drug. The last decade has seen significant progress in SCARs research. Recent studies have unveiled the pathogenesis of SCARs involved in susceptible genes, including human leukocyte antigens (HLA) and drugs-T cell receptor (TCR) interaction that may trigger T cell activation with downstream immune signaling of cytokines/chemokines and specific cytotoxic proteins releases. Advances in identification of multiple genetic alleles associated with specific drugs related SCARS in different populations is an important breakthrough in recent years for prevention of SCARs. This article summarized the findings on genetic factors related to SJS/TEN, especially for HLA.

Efficacy and safety of levetiracetam versus (fos)phenytoin for second-line treatment of epilepticus: a meta-analysis of latest randomized controlled trials

OBJECTIVES

To assess the efficiency and safety profiles of levetiracetam and (fos)phenytoin (phenytoin or fosphenytoin) for second-line treatment of seizures by performing a meta-analysis of RCTs.

METHODS

We systematically searched PubMed, Embase, Cochrane, FDA.gov, and ClinicalTrials.gov for RCTs (published before July 31, 2020; no language restrictions). Two independent reviewers screened abstracts and titles against inclusion and exclusion criteria published previously in the PROSPERO: CRD42020202736. Eleven studies fulfilled the established criteria. We assessed pooled data by using a random-effects model. Quality analysis was performed by using version 2 of the Cochrane risk-of-bias tool (RoB 2). RevMan v.5.3 was used to perform statistical analyses, and publication bias (egger's test) was assessed with Stata MP v.14.0.

RESULTS

Levetiracetam was similar to (fos)phenytoin in seizure termination rate (risk ratio [RR] 0.94; 95% CI 0.87 to 1.01), time of seizure termination (mean difference [MD] 0.44; -0.60 to 1.49), and drug resistance ([RR] 1.12, 0.86 to 1.45). The safety outcome showed a significant statistical difference between fosphenytoin group and levetiracetam group ([RR] 1.44, 1.14 to 1.81), while there was no significant difference observed between phenytoin treatment and levetiracetam treatment ([RR] 1.26, 0.99 to 1.60).

CONCLUSION

Levetiracetam was similar to (fos)phenytoin in cessation rate convulsive status epilepticus, and drug resistance, while it was superior (fos)phenytoin in pooled safety outcome. Further exploration is still needed as to whether it is the first choice for second-line drugs.

Spectrum of cutaneous adverse reactions to aromatic antiepileptic drugs and human leukocyte antigen genotypes in Thai patients and meta-analysis

Aromatic antiepileptic drugs (AEDs)-induced cutaneous adverse drug reactions (cADRs) add up to the limited use of the AEDs in the treatment and prevention of seizures. Human leukocyte antigen-B (HLA-B) alleles have been linked to AEDs-induced cADRs. We investigated the association between cADRs (including Stevens-Johnson syndrome; SJS/toxic epidermal necrolysis; TEN, drug reaction with eosinophilia and systemic symptoms; DRESS, and Maculopapular eruption; MPE) caused by AEDs (phenytoin, carbamazepine, lamotrigine, phenobarbital and oxcarbazepine) and HLA-B alleles in Thai population. Through the case-control study, 166 patients with AEDs-induced cADRs, 426 AEDs-tolerant patients (AEDs-tolerant controls), and 470 healthy subjects (Thai population) were collected. The HLA genotypes were detected using the polymerase chain reaction-sequence specific oligonucleotide probe (PCR-SSOP) method. We also performed a meta-analysis with these data and other populations. The carrier rate of HLA-B*15:02 was significantly different between AEDs-induced cADRs group and AEDs-tolerant group (Odds ratio; OR 4.28, 95% Confidence interval; CI 2.64-6.95, p < 0.001), AEDs-induced cADRs group and Thai population (OR 2.15, 95%CI 1.41-3.29, p < 0.001). In meta-analysis showed the strong association HLA-B*15:02 with AEDs-induced cADRs (OR 4.77, 95%CI 1.79-12.73, p < 0.001). Furthermore, HLA-B*15:02 was associated with SJS/TEN induced by AEDs (OR 10.28, 95%CI 6.50-16.28, p < 0.001) Phenytoin (OR 4.12, 95%CI 1.77-9.59, p = 0.001) and carbamazepine (OR 137.69, 95%CI 50.97-371.98, p < 0.001). This study demonstrated that genetic association for AEDs-induced cADRs was phenotype-specific. A strong association between HLA-B*15:02 and AEDs-induced SJS/TEN was demonstrated with an OR of 10.79 (95%CI 5.50-21.16, p < 0.001) when compared with AEDs-tolerant group. On the other hand, the carrier rates of HLA-B*08:01, HLA-B*13:01, and HLA-B*56:02 were significantly higher in the DRESS group compared with the AEDs-tolerant group (p = 0.029, 0.007, and 0.017, respectively). The HLA-B*15:02 allele may represent a risk factor for AEDs-induced cADRs.

Heater Integrated Lab-on-a-Chip Device for Rapid HLA Alleles Amplification towards Prevention of Drug Hypersensitivity

HLA-B*15:02 screening before administering carbamazepine is recommended to prevent life-threatening hypersensitivity. However, the unavailability of a point-of-care device impedes this screening process. Our research group previously developed a two-step HLA-B*15:02 detection technique utilizing loop-mediated isothermal amplification (LAMP) on the tube, which requires two-stage device development to translate into a portable platform. Here, we report a heater-integrated lab-on-a-chip device for the LAMP amplification, which can rapidly detect HLA-B alleles colorimetrically. A gold-patterned micro-sized heater was integrated into a 3D-printed chip, allowing microfluidic pumping, valving, and incubation. The performance of the chip was tested with color dye. Then LAMP assay was conducted with human genomic DNA samples of known HLA-B genotypes in the LAMP-chip parallel with the tube assay. The LAMP-on-chip results showed a complete match with the LAMP-on-tube assay, demonstrating the detection system's concurrence.

Genetic Determinants in HLA and Cytochrome P450 Genes in the Risk of Aromatic Antiepileptic-Induced Severe Cutaneous Adverse Reactions

Adverse drug reaction (ADR) is a pressing health problem, and one of the main reasons for treatment failure with antiepileptic drugs. This has become apparent in the event of severe cutaneous adverse reactions (SCARs), which can be life-threatening. In this review, four hypotheses were identified to describe how the immune system is triggered in the development of SCARs, which predominantly involve the human leukocyte antigen (HLA) proteins. Several genetic variations in HLA genes have been shown to be strongly associated with the susceptibility to developing SCARs when prescribed carbamazepine or phenytoin. These genetic variations were also shown to be prevalent in certain populations. Apart from the HLA genes, other genes proposed to affect the risk of SCARs are genes encoding for CYP450 drug-metabolising enzymes, which are involved in the pharmacokinetics of offending drugs. Genetic variants in CYP2C9 and CYPC19 enzymes were also suggested to modulate the risk of SCARs in some populations. This review summarizes the literature on the manifestation and aetiology of antiepileptic-induced SCARs, updates on pharmacogenetic markers associated with this reaction and the implementation of pre-emptive testing as a preventive strategy for SCARs.

Pharmacogenomics research and its clinical implementation in Thailand: Lessons learned from the resource-limited settings

Several barriers present challenges to implementing pharmacogenomics into practice. This review will provide an overview of the current pharmacogenomics practices and research in Thailand, address the challenges and lessons learned from delivering clinical pharmacogenomic services in Thailand, emphasize the pharmacogenomics implementation issues that must be overcome, and identify current pharmacogenomic initiatives and plans to facilitate clinical implementation of pharmacogenomics in Thailand. Ever since the pharmacogenomics research began in 2004 in Thailand, a multitude of pharmacogenomics variants associated with drug responses have been identified in the Thai population, such as HLA-B∗15:02 for carbamazepine and oxcarbazepine, HLA-B∗58:01 for allopurinol, HLA-B∗13:01 for dapsone and cotrimoxazole, CYP2B6 variants for efavirenz, CYP2C9∗3 for phenytoin and warfarin, CYP3A5∗3 for tacrolimus, and UGT1A1∗6 and UGT1A1∗28 for irinotecan, etc. The future of pharmacogenomics guided therapy in clinical settings across Thailand appears promising because of the availability of evidence of clinical validity of the pharmacogenomics testing and support for reimbursement of pharmacogenomics testing.

Characterization of T-Cell Responses to SMX and SMX-NO in Co-Trimoxazole Hypersensitivity Patients Expressing HLA-B*13:01

HLA-B*13:01-positive patients in Thailand can develop frequent co-trimoxazole hypersensitivity reactions. This study aimed to characterize drug-specific T cells from three co-trimoxazole hypersensitive patients presenting with either Stevens-Johnson syndrome or drug reaction with eosinophilia and systemic symptoms. Two of the patients carried the HLA allele of interest, namely HLA-B*13:01. Sulfamethoxazole and nitroso sulfamethoxazole specific T cell clones were generated from T cell lines of co-trimoxazole hypersensitive HLA-B*13:01-positive patients. Clones were characterized for antigen specificity and cross-reactivity with structurally related compounds by measuring proliferation and cytokine release. Surface marker expression was characterized via flow cytometry. Mechanistic studies were conducted to assess pathways of T cell activation in response to antigen stimulation. Peripheral blood mononuclear cells from all patients were stimulated to proliferate and secrete IFN-γ with nitroso sulfamethoxazole. All sulfamethoxazole and nitroso sulfamethoxazole specific T cell clones expressed the CD4+ phenotype and strongly secreted IL-13 as well as IFN-γ, granzyme B and IL-22. No secretion of IL-17 was observed. A number of nitroso sulfamethoxazole-specific clones cross-reacted with nitroso dapsone but not sulfamethoxazole whereas sulfamethoxazole specific clones cross-reacted with nitroso sulfamethoxazole only. The nitroso sulfamethoxazole specific clones were activated in both antigen processing-dependent and -independent manner, while sulfamethoxazole activated T cell responses via direct HLA binding. Furthermore, activation of nitroso sulfamethoxazole-specific, but not sulfamethoxazole-specific, clones was blocked with glutathione. Sulfamethoxazole and nitroso sulfamethoxazole specific T cell clones from hypersensitive patients were CD4+ which suggests that HLA-B*13:01 is not directly involved in the iatrogenic disease observed in co-trimoxazole hypersensitivity patients.

Current Pharmacogenetic Perspective on Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

Adverse drug reactions are a public health issue that draws widespread attention, especially for Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) which have high mortality and lack of efficacious treatment. Though T-cell-mediated HLA-interacted immune response has been extensively studied, our understanding of the mechanism is far from satisfactory. This review summarizes infection (virus, bacterial, and mycoplasma infection), an environmental risk factor, as a trigger for SJS/TEN. The mutations or polymorphisms of drug metabolic enzymes, transporters, receptors, the immune system genes, and T-cell-mediated apoptosis signaling pathways that contribute to SJS/TEN are discussed and summarized. Epigenetics, metabolites, and mobilization of regulatory T cells and tolerogenic myeloid precursors are emerged directions to study SJS/TEN. Ex vivo lymphocyte transformation test has been exploited to aid in identifying the causative drugs. Critical questions on the pathogenesis of SJS/TEN underlying gene polymorphisms and T cell cytotoxicity remain: why some of the patients carrying the risky genes tolerate the drug and do not develop SJS/TEN? What makes the skin and mucous membrane so special to be targeted? Do they relate to skin/mucous expression of transporters? What is the common machinery underlying different HLA-B alleles associated with SJS/TEN and common metabolites?

Genomic Risk Factors Driving Immune-Mediated Delayed Drug Hypersensitivity Reactions

Adverse drug reactions (ADRs) remain associated with significant mortality. Delayed hypersensitivity reactions (DHRs) that occur greater than 6 h following drug administration are T-cell mediated with many severe DHRs now associated with human leukocyte antigen (HLA) risk alleles, opening pathways for clinical prediction and prevention. However, incomplete negative predictive value (NPV), low positive predictive value (PPV), and a large number needed to test (NNT) to prevent one case have practically prevented large-scale and cost-effective screening implementation. Additional factors outside of HLA contributing to risk of severe T-cell-mediated DHRs include variation in drug metabolism, T-cell receptor (TCR) specificity, and, most recently, HLA-presented immunopeptidome-processing efficiencies via endoplasmic reticulum aminopeptidase (ERAP). Active research continues toward identification of other highly polymorphic factors likely to impose risk. These include those previously associated with T-cell-mediated HLA-associated infectious or auto-immune disease such as Killer cell immunoglobulin-like receptors (KIR), epistatically linked with HLA class I to regulate NK- and T-cell-mediated cytotoxic degranulation, and co-inhibitory signaling pathways for which therapeutic blockade in cancer immunotherapy is now associated with an increased incidence of DHRs. As such, the field now recognizes that susceptibility is not simply a static product of genetics but that individuals may experience dynamic risk, skewed toward immune activation through therapeutic interventions and epigenetic modifications driven by ecological exposures. This review provides an updated overview of current and proposed genetic factors thought to predispose risk for severe T-cell-mediated DHRs.

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.

Possible interplay between the theories of pharmacoresistant epilepsy

Epilepsy is one of the oldest known neurological disorders and is characterized by recurrent seizure activity. It has a high incidence rate, affecting a broad demographic in both developed and developing countries. Comorbid conditions are frequent in patients with epilepsy and have detrimental effects on their quality of life. Current management options for epilepsy include the use of anti-epileptic drugs, surgery, or a ketogenic diet. However, more than 30% of patients diagnosed with epilepsy exhibit drug resistance to anti-epileptic drugs. Further, surgery and ketogenic diets do little to alleviate the symptoms of patients with pharmacoresistant epilepsy. Thus, there is an urgent need to understand the underlying mechanisms of pharmacoresistant epilepsy to design newer and more effective anti-epileptic drugs. Several theories of pharmacoresistant epilepsy have been suggested over the years, the most common being the gene variant hypothesis, network hypothesis, multidrug transporter hypothesis, and target hypothesis. In our review, we discuss the main theories of pharmacoresistant epilepsy and highlight a possible interconnection between their mechanisms that could lead to the development of novel therapies for pharmacoresistant epilepsy.

Evaluation of clinical and genetic factors in the population pharmacokinetics of carbamazepine

Aims

Carbamazepine can cause hypersensitivity reactions in ~10% of patients. An immunogenic effect can be produced by the electrophilic 10,11‐epoxide metabolite but not by carbamazepine. Hypothetically, certain single nucleotide polymorphisms might increase the formation of immunogenic metabolites, leading ultimately to hypersensitivity reactions. This study explores the role of clinical and genetic factors in the pharmacokinetics (PK) of carbamazepine and 3 metabolites known to be chemically reactive or formed through reactive intermediates.

Methods

A combination of rich and sparse PK samples were collected from healthy volunteers and epilepsy patients. All subjects were genotyped for 20 single nucleotide polymorphisms in 11 genes known to be involved in the metabolism or transport of carbamazepine and carbamazepine 10,11‐epoxide. Nonlinear mixed effects modelling was used to build a population‐PK model.

Results

In total, 248 observations were collected from 80 subjects. A 1‐compartment PK model with first‐order absorption and elimination best described the parent carbamazepine data, with a total clearance of 1.96 L/h, central distribution volume of 164 L and absorption rate constant of 0.45 h⁻¹. Total daily dose and coadministration of phenytoin were significant covariates for total clearance of carbamazepine. EPHX1‐416G/G genotype was a significant covariate for the clearance of carbamazepine 10,11‐epoxide.

Conclusion

Our data indicate that carbamazepine clearance was affected by total dose and phenytoin coadministration, but not by genetic factors, while carbamazepine 10,11‐epoxide clearance was affected by a variant in the microsomal epoxide hydrolase gene. A much larger sample size would be required to fully evaluate the role of genetic variation in carbamazepine pharmacokinetics, and thereby predisposition to carbamazepine hypersensitivity.

Investigating the association of Lamotrigine and Phenytoin-induced Stevens-Johnson syndrome/Toxic Epidermal Necrolysis with HLA-B*1502 in Iranian population

Previous studies have found an association between HLA-B*1502 allele and lamotrigine-induced Stevens-Johnson syndrome (SJS)/ toxic epidermal necrosis (TEN) spectrum in Han Chinese populations. This study aims to investigate the association between HLA-B*1502 and lamotrigine- or phenytoin- induced SJS/TEN in an Iranian population. The medical records of twenty-eight lamotrigine-induced SJS/TEN patients and twenty-five lamotrigine-tolerant controls as well as eight phenytoin-induced SJS/TEN and twelve phenytoin-tolerant controls were extracted between March 2013 and March 2019 from the university hospitals in Mashhad, Iran. The presence of HLA-B*1502 allele was determined using real-time polymerase chain reaction (PCR). Among lamotrigine-induced patients with SJS/TEN, 11 (39.3%) patients tested positive for the HLA-B*1502 while only 3 (12.0%) of the lamotrigine-tolerant controls tested positive for this allele. The risk of lamotrigine-induced SJS/TEN was significantly higher in patients with HLA-B*1502, with an odds ratio (OR) of 4.74 [95% confidence interval (CI) 1.14-19.73, p = 0.032]. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of HLA-B*1502 for lamotrigine-induced SJS/TEN was 39.29%, 88.00%, 78.57% and 56.41%, respectively. The HLA-B*1502 allele was present in 2 (25.0%) of phenytoin-induced SJS/TEN cases and 5 (41.7%) of the phenytoin-tolerant controls tested positive for HLA-B*1502 allele. The risk of phenytoin-induced SJS/TEN was not higher in the patients with HLA-B*1502 (OR = 0.467 [95% confidence interval (CI) 0.065-3.34, p = 0.642]). Lamotrigine-induced SJS/TEN is associated with HLA-B*1502 allele in an Iranian population but this is not the case for phenytoin-induced SJS/TEN.

Challenges and Opportunities in Implementing Pharmacogenetic Testing in Clinical Settings

The clinical implementation of pharmacogenetic biomarkers continues to grow as new genetic variants associated with drug outcomes are discovered and validated. The number of drug labels that contain pharmacogenetic information also continues to expand. Published, peer-reviewed clinical practice guidelines have also been developed to support the implementation of pharmacogenetic tests. Incorporating pharmacogenetic information into health care benefits patients as well as clinicians by improving drug safety and reducing empiricism in drug selection. Barriers to the implementation of pharmacogenetic testing remain. This review explores current pharmacogenetic implementation initiatives with a focus on the challenges of pharmacogenetic implementation and potential opportunities to overcome these challenges.

Diagnostic Test Criteria for HLA Genotyping to Prevent Drug Hypersensitivity Reactions: A Systematic Review of Actionable HLA Recommendations in CPIC and DPWG Guidelines

Introduction

Certain HLA variants are associated with an increased risk of hypersensitivity reactions to specific drugs. Both the Clinical Pharmacogenetics Implementation Consortium (CPIC) and the Dutch Pharmacogenetics Working Group (DPWG) have issued actionable HLA gene - drug interaction guidelines but diagnostic test criteria remain largely unknown. We present an overview of the diagnostic test criteria of the actionable HLA - drug pairs.

Methods

A systematic literature search was conducted in PubMed, Embase, Web of Science and Cochrane Library. Original case-control and cohort studies were selected and sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and number needed to genotype (NNG) were calculated for the actionable HLA-drug pairs.

Results

In general, the HLA tests show high specificity and NPV for predicting hypersensitivity reactions. The sensitivity of HLA tests shows a wide range, from 0-33% for HLA-B*1502 testing to predict lamotrigine induced SJS/TEN up to 100% for HLA-B*5701 to predict immunologically confirmed abacavir hypersensitivity syndrome (ABC-HSR). PPV is low for all tests except for HLA-B*5701 and ABC-HSR which is approximately 50%. HLA-B*5701 to predict ABC-HSR shows the lowest NNG followed by HLA-B*5801 for allopurinol induced severe cutaneous adverse drug reactions and HLA-B*1502 for carbamazepine induced SJS/TEN.

Discussion

This is the first overview of diagnostic test criteria for actionable HLA-drug pairs. Studies researching HLA genes and hypersensitivity are scarce for some of the HLA-drug pairs in some populations and patient numbers in studies are small. Therefore, more research is necessary to calculate the diagnostic test criteria more accurately.