Association of HLA-A*11:01 with Sulfonamide-Related Severe Cutaneous Adverse Reactions in Japanese Patients

Oral Antibiotics and Risk of Serious Cutaneous Adverse Drug Reactions

Importance

Serious cutaneous adverse drug reactions (cADRs) are potentially life-threatening drug hypersensitivity reactions involving the skin and internal organs. Antibiotics are a recognized cause of these reactions, but no studies have compared relative risks across antibiotic classes.

Objectives

To explore the risk of serious cADRs associated with commonly prescribed oral antibiotics, and to characterize outcomes of patients hospitalized for them.

Design, Setting, and Participants

Nested case-control study using population-based linked administrative datasets among adults aged 66 years or older who received at least 1 oral antibiotic between 2002 and 2022 in Ontario, Canada. Cases were those who had an emergency department (ED) visit or hospitalization for serious cADRs within 60 days of the prescription, and each case was matched with up to 4 controls who did not.

Exposure

Various classes of oral antibiotics.

Main Outcomes and Measures

Conditional logistic regression estimate of the association between different classes of oral antibiotics and serious cADRs, using macrolides as the reference group.

Results

During the 20-year study period, we identified 21 758 older adults (median age, 75 years; 64.1% female) who had an ED visit or hospitalization for serious cADRs following antibiotic therapy and 87 025 matched controls who did not. In the primary analysis, sulfonamide antibiotics (adjusted odds ratio [aOR], 2.9; 95% CI, 2.7-3.1) and cephalosporins (aOR, 2.6; 95% CI, 2.5-2.8) were most strongly associated with serious cADRs relative to macrolides. Additional associations were evident with nitrofurantoin (aOR, 2.2; 95% CI, 2.1-2.4), penicillins (aOR, 1.4; 95% CI, 1.3-1.5), and fluoroquinolones (aOR, 1.3; 95% CI, 1.2-1.4). The crude rate of ED visits or hospitalization for cADRs was highest for cephalosporins (4.92 per 1000 prescriptions; 95% CI, 4.86-4.99) and sulfonamide antibiotics (3.22 per 1000 prescriptions; 95% CI, 3.15-3.28). Among the 2852 case patients hospitalized for cADRs, the median length of stay was 6 days (IQR, 3-13 days), 9.6% required transfer to a critical care unit, and 5.3% died in the hospital.

Conclusion and Relevance

Commonly prescribed oral antibiotics are associated with an increased risk of serious cADRs compared with macrolides, with sulfonamides and cephalosporins carrying the highest risk. Prescribers should preferentially use lower-risk antibiotics when clinically appropriate.

HLA-DPB1*05:01 and HLA-A*11:01 Is Associated with Adverse Drug Reactions to Isoniazid and Rifampin for Treatment of Latent Tuberculosis Infection in South Korea

Background: Screening and treating healthcare workers (HCWs) for latent tuberculosis infection (LTBI) are essential for tuberculosis (TB) infection control. Adverse drug reactions (ADRs) to anti-TB drugs present challenges to patient safety and treatment completion. Objective: This study investigated the association between human leukocyte antigen (HLA) alleles and the risk of ADRs, especially drug hypersensitivity (DHS) and hepatotoxicity, in HCWs with LTBI receiving isoniazid (INH) and rifampin (RIF) therapy. Methods: Korean HCWs with LTBI who received a 3 month INH and RIF regimen were included in this study. HLA genotyping was performed on HCWs who experienced ADRs during treatment, as well as the control group consisted of individuals who did not develop ADRs. Results: Of the 67 patients, 29 (43.2%) experienced ADRs during INH and RIF therapy. The HLA-A*11:01 allele was more frequent in patients with DHS without hepatotoxicity (DSH+/H-) compared to the control group (DHS-/H-) (4/9, 44.4% vs. 3/38, 7.9%; odd ratio [OR], 8.554; 95% confidence interval [CI], 1.415-59.869; p = 0.018). Conversely, HLA-DPB1*05:01 was associated with an increased risk of hepatotoxicity regardless of DHS (10/20, 50% vs. 5/38, 13.2%; OR, 5.323; 95% CI, 1.493-21.518; p = 0.011). In the DHS with hepatotoxicity group (DHS+/H+), HLA-DPB1*05:01 was present in a higher proportion (3/5, 60% vs. 5/38, 13.2%; OR, 8.912; 95% CI, 1.110-92.993; p = 0.037), whereas HLA-A*11:01 was not observed in this group. Conclusions: The HLA-A*11:01 allele was associated with an increased risk of DHS without hepatotoxicity, whereas the HLA-DPB1*05:01 allele was associated with an increased risk of hepatotoxicity.

Human Leukocyte Antigens and Sulfamethoxazole/Cotrimoxazole-Induced Severe Cutaneous Adverse Reactions: A Systematic Review and Meta-Analysis

Importance

Sulfamethoxazole (SMX) and cotrimoxazole (CTX), a fixed-dose combination of SMX and trimethoprim in a 5:1 ratio, are antibacterial sulfonamides commonly used for treating various diseases. A substantial prevalence of severe cutaneous adverse reactions (SCARs) following the administration of these drugs has been reported. However, the association between human leukocyte antigen (HLA) genotypes and SMX/CTX-induced SCARs has remained unclear.

Objective

To investigate the association between HLA genotypes and SMX/CTX-induced SCARs.

Data sources

A comprehensive search was conducted in CENTRAL (Cochrane Library), MEDLINE, and Embase from inception to January 17, 2023.

Study Selection

Case-control studies that recruited patients who had experienced SCARs following SMX or CTX were included, and HLA alleles were analyzed.

Data Extraction and Synthesis

Two independent authors extracted data on study characteristics and outcome data. The Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guideline and the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guidelines were followed. The Newcastle-Ottawa Scale for case-control studies was used to assess study quality. Odds ratios (ORs) were calculated using a random-effects model for meta-analysis.

Main Outcomes and Measures

The prespecified outcome was the OR comparing SMX/CTX-induced SCARs with healthy or SMX/CTX-tolerant controls based on different HLA alleles.

Results

Six studies involving 322 patients with SCAR were included, including 236 patients with Stevens-Johnson syndrome/toxic epidermal necrolysis, 86 with drug reaction with eosinophilia and systemic symptoms, 8448 healthy controls, and 229 tolerant controls. Significant associations were found in HLA-A*11:01 (OR, 2.10; 95% CI, 1.11-4.00), HLA-B*13:01 (OR, 5.96; 95% CI, 1.58-22.56), HLA-B*15:02 (OR, 2.23; 95% CI, 1.20-4.14), HLA-B*38:02 (OR, 3.47; 95% CI, 1.42-8.48), and HLA-C*08:01 (OR, 2.63; 95% CI, 1.07-6.44) compared with tolerant controls. In the Stevens-Johnson syndrome/toxic epidermal necrolysis subgroup, significant associations were found in HLA-B*15:02 (OR, 3.01; 95% CI, 1.56-5.80) and HLA-B*38:02 (OR, 5.13; 95% CI, 1.96-13.47). In the drug reaction with eosinophilia and systemic symptoms subgroup, significant associations were found in HLA-A*68:01 (OR, 12.86; 95% CI, 1.09-151.34), HLA-B*13:01 (OR, 23.09; 95% CI, 3.31-161.00), HLA-B*39:01 (OR, 4.56; 95% CI, 1.31-15.82).

Conclusions and Relevance

The results of this systematic review and meta-analysis suggest that multiple HLA alleles (HLA-A*11:01, HLA-B*13:01, HLA-B*15:02, HLA-B*38:02, and HLA-C*0801) are associated with SMX/CTX-induced SCARs.

Drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms. Part I. Epidemiology, pathogenesis, clinicopathological features, and prognosis

Drug-induced hypersensitivity syndrome (DiHS), also known as drug reaction with eosinophilia and systemic symptoms (DRESS), is a severe cutaneous adverse reaction (SCAR) characterized by an exanthem, fever, and hematologic and visceral organ involvement. Anticonvulsants, antibiotics, and allopurinol are the most common triggers. The pathogenesis involves a complex interplay between drugs, viruses, and the immune system primarily mediated by T-cells. DiHS/DRESS typically presents with a morbilliform eruption 2-6 weeks after drug exposure, and is associated with significant morbidity, mortality, and risk of relapse. Long-term sequelae primarily relate to organ dysfunction and autoimmune diseases. Part I of this continuing medical education activity on DiHS/DRESS provides an update on epidemiology, novel insights into pathogenesis, and a description of clinicopathological features and prognosis.

Risk of Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis Associated With Antibiotic Use: A Case-Crossover Study

BACKGROUND

Evidence is lacking on the association between antibiotic use and risk of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) in Asians.

OBJECTIVE

We assessed the risk of SJS/TEN associated with different antibiotic classes in Japanese.

METHODS

We conducted a case-crossover study using a claims database. Firth conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of SJS/TEN associated with antibiotic use in a 56-day hazard period versus 3 control periods. We created 18 cohorts for each antibiotic class and calculated 56-day cumulative incidence per 100,000 new users. The association between antibiotic class and SJS/TEN was also evaluated in each case using the ALgorithm of Drug causality for Epidermal Necrolysis (ALDEN).

RESULTS

Our case-crossover study included 170 SJS/TEN cases. Increased ORs were observed for lincomycins (OR, 33.00 [95% CI, 3.74-4332.05]), trimethoprim-sulfamethoxazole (21.20 [6.73-105.98]), penicillins (14.39 [6.95-34.21]), glycopeptides (14.37 [3.17-136.10]), cephalosporins (7.06 [4.25-12.21]), aminoglycosides (6.55 [1.97-26.84]), quinolones (5.98 [3.34-11.20]), fosfomycin (5.40 [1.20-30.97]), carbapenems (5.09 [1.85-15.64]), tetracyclines (4.95 [1.78-15.27]), and macrolides (3.78 [2.13-6.83]). Cumulative incidence of SJS/TEN was 67.4 for trimethoprim-sulfamethoxazole, 86.2 for glycopeptides, and below 10.0 for the others. Despite the high incidence, only 2 cases had a probable causal relationship with glycopeptides.

CONCLUSION

Some antibiotic classes, including lincomycins, glycopeptides, aminoglycosides, fosfomycin, and carbapenems, were newly suggested to be associated with risk of SJS/TEN; considered together with the high incidence for trimethoprim-sulfamethoxazole and glycopeptides, these findings warrant caution in clinical practice.

Genotypic and Phenotypic Characteristics of Co-Trimoxazole-Induced Cutaneous Adverse Reactions

BACKGROUND

Co-trimoxazole has been reported as a common culprit drug for various cutaneous adverse drug reactions (CADRs). However, information on genotypic and phenotypic characteristics is still limited. We aimed to study clinical characteristics, genetic suitability, laboratory findings, and treatment outcomes in patients with co-trimoxazole-induced CADR and determine variables associated with severe cutaneous adverse reactions (SCARs).

METHODS

The medical records of all patients diagnosed with co-trimoxazole-induced CADR during October 2015 and October 2021 were reviewed. Clinical characteristics and laboratory investigation with an emphasis on human leukocyte antigen (HLA) class I and HLA-DRB1 results linked to subtypes of cutaneous adverse reactions were evaluated.

RESULTS

Seventy-two patients diagnosed with co-trimoxazole-induced CADR were included in the study. Mean age at diagnosis was 38.0 ± 14.6 years old, and 72% were female. Subtypes of reactions included maculopapular eruption (MPE; 56.9%), drug reaction with eosinophilia and systemic symptoms (DRESS; 23.6%), Stevens-Johnson syndrome (SJS; 12.5%), fixed drug eruption (4.2%), and urticaria (2.8%). Characteristics that were significantly associated with SCARs included male gender (OR = 3.01, 95% CI: 1.04-8.75), HIV infection (OR = 3.48, 95% CI: 1.13-10.75), prophylactic use of co-trimoxazole (OR = 4.89, 95% CI: 1.54-15.57), and co-trimoxazole administration longer than 10 days (OR = 7.65, 95% CI: 2.57-22.78). HLA-B*38:02 was associated with co-trimoxazole-induced SJS, while HLA-A*11:01, HLA-B*13:01, and HLA-DRB1*12:01 were associated with co-trimoxazole-induced DRESS. HLA-B*52:01 was associated with co-trimoxazole-induced MPE.

CONCLUSIONS

Co-trimoxazole could induce various phenotypes of CADRs. Genotypic and phenotypic factors that may potentially predict co-trimoxazole-induced SCARs include male gender, HIV infection, prophylactic and prolonged drug use, as well as the presence of HLA-A*11:01, HLA-B*13:01, HLA-B*38:02, or HLA-DRB1*12:01 alleles.

Advances in understanding of the pathogenesis and therapeutic implications of drug reaction with eosinophilia and systemic symptoms: an updated review

Drug reaction with eosinophilia and systemic symptoms or drug-induced hypersensitivity syndrome (DRESS/DIHS) is one type of severe cutaneous adverse reaction (SCAR). It is featured by fever, widespread skin lesions, protracted clinical course, internal organ involvement, and possibly long-term autoimmune sequelae. The presence of high-risk human leukocyte antigen (HLA) alleles, hypersensitivity reaction after culprit drug ingestion, and human herpesvirus reactivation may all contribute to its complex clinical manifestations. Some recent studies focusing on the roles of involved cytokines/chemokines and T cells co-signaling pathways in DRESS/DIHS were conducted. In addition, some predictors of disease severity and prognosis were also reported. In this review, we provided an update on the current understanding of the pathogenesis, potential biomarkers, and the relevant therapeutic rationales of DRESS/DIHS.

Current understanding of genetic associations with delayed hypersensitivity reactions induced by antibiotics and anti-osteoporotic drugs

Drug-induced delayed hypersensitivity reactions (DHRs) is still a clinical and healthcare burden in every country. Increasing reports of DHRs have caught our attention to explore the genetic relationship, especially life-threatening severe cutaneous adverse drug reactions (SCARs), including acute generalized exanthematous pustulosis (AGEP), drug reactions with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). In recent years, many studies have investigated the immune mechanism and genetic markers of DHRs. Besides, several studies have stated the associations between antibiotics-as well as anti-osteoporotic drugs (AOD)-induced SCARs and specific human leukocyte antigens (HLA) alleles. Strong associations between drugs and HLA alleles such as co-trimoxazole-induced DRESS and HLA-B*13:01 (Odds ratio (OR) = 45), dapsone-DRESS and HLA-B*13:01 (OR = 122.1), vancomycin-DRESS and HLA-A*32:01 (OR = 403), clindamycin-DHRs and HLA-B*15:27 (OR = 55.6), and strontium ranelate (SR)-SJS/TEN and HLA-A*33:03 (OR = 25.97) are listed. We summarized the immune mechanism of SCARs, update the latest knowledge of pharmacogenomics of antibiotics- and AOD-induced SCARs, and indicate the potential clinical use of these genetic markers for SCARs prevention in this mini review article.

Worldwide Prevalence of Antibiotic-Associated Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis: A Systematic Review and Meta-analysis

Importance

Antibiotics are an important risk for Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN), which are the most severe types of drug hypersensitivity reaction with a mortality rate up to 50%. To our knowledge, no global systematic review has described antibiotic-associated SJS/TEN.

Objective

To evaluate the prevalence of antibiotics associated with SJS/TEN worldwide.

Data Sources

The MEDLINE and Embase databases were searched for experimental and observational studies that described SJS/TEN risks since database inception to February 22, 2022.

Study Selection

Included studies adequately described SJS/TEN origins and specified the antibiotics associated with SJS/TEN.

Data Extraction and Synthesis

Two reviewers (E.Y.L. and C.K.) independently selected the studies, extracted the data, and assessed the risk of bias. A meta-analysis using a random-effects model was performed in the studies that described patient-level associations. Subgroup analyses were performed to explore the heterogeneity. The risk of bias was assessed using the Joanna Briggs Institute checklist, and the certainty of evidence was rated using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach.

Main Outcomes and Measures

Prevalence of antibiotic-associated SJS/TEN was presented as pooled proportions with 95% CIs.

Results

Among the 64 studies included in the systematic review, there were 38 studies that described patient-level associations; the meta-analysis included these 38 studies with 2917 patients to determine the prevalence of single antibiotics associated with SJS/TEN. The pooled proportion of antibiotics associated with SJS/TEN was 28% (95% CI, 24%-33%), with moderate certainty of evidence. Among antibiotic-associated SJS/TEN, the sulfonamide class was associated with 32% (95% CI, 22%-44%) of cases, followed by penicillins (22%; 95% CI, 17%-28%), cephalosporins (11%; 95% CI, 6%-17%), fluoroquinolones (4%; 95% CI, 1%-7%), and macrolides (2%; 95% CI, 1%-5%). There was a statistically significant heterogeneity in the meta-analysis, which could be partially explained in the subgroup analysis by continents. The overall risk of bias was low using the Joanna Briggs Institute checklist for case series.

Conclusion and Relevance

In this systematic review and meta-analysis of all case series, antibiotics were associated with more than one-quarter of SJS/TEN cases described worldwide, and sulfonamide antibiotics remained the most important association. These findings highlight the importance of antibiotic stewardship, clinician education and awareness, and weighing the risk-benefit assessment of antibiotic choice and duration.

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.

Significant association between HLA-B*35:01 and onset of drug-induced liver injury caused by Kampo medicines in Japanese patients

AIM

Drug-induced liver injury (DILI) is a severe and life-threatening immune-mediated adverse effect, occurring rarely among treated patients. We examined genomic biomarkers in the Japanese population that predict the onset of DILI after using a certain class of drugs, such as Kampo products (Japanese traditional medicines).

METHODS

A total of 287 patients diagnosed as DILI by hepatology specialists were recruited after written informed consent was obtained. A genome-wide association analysis and human leukocyte antigen (HLA) typing in four digits were performed.

RESULTS

We found a significant association (p = 9.41 × 10^-10 ) of rs146644517 (G > A) with Kampo product-related DILI. As this polymorphism is located in the HLA region, we evaluated the association of HLA types and found that 12 (63.2%) of 19 Kampo-DILI patients contained HLA-B*35:01, whereas only 15.2% were positive for this HLA among healthy volunteers. The odds ratio was 9.56 (95% confidence interval 3.75-24.46; p = 2.98 × 10^-6 , corrected p = 4.17 × 10^-5 ), and it increased to 13.55 compared with the DILI patients not exposed to Kampo products. The individual crude drug components in the Kampo products, including Scutellaria root (ougon in Japanese), rhubarb (daiou), Gardenia fruit (sanshishi), and Glycyrrhiza (kanzou), were significantly associated with HLA-B*35:01.

CONCLUSIONS

HLA-B*35:01 is a genetic risk factor and a potential predictive biomarker for Kampo-induced DILI in the Japanese population.

Clinical Manifestations and Genetic Influences in Sulfonamide-Induced Hypersensitivity

Drug hypersensitivity is an inflammatory or immune reaction induced by drugs. It can be fatal if not appropriately treated and cause the risk of long-term complications. Sulfonamides are classified as antimicrobial drugs with a broad spectrum effective for gram-positive and gram-negative bacteria. This antibacterial agent works by competitively inhibiting folic acid synthesis, which prevents the growth and proliferation of microorganisms. In its use as antibiotics, sulfonamides can also cause adverse reactions in specific individuals. It has been widely reported that sulfonamide antimicrobials cause hypersensitivity reactions mediated by IgE or T cells. This review identifies symptoms or signs that can appear, as well as genes associated with sulfonamide hypersensitivity reactions, as sulfonamide may cause hypersensitivity in the form of uveitis, skin rash, Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN), parotitis, angioedema, drug reaction with eosinophilia and systemic symptoms (DRESS), and pruritus. In addition, several genes were found to be associated with sulfonamide hypersensitivity, including HLA-A29, HLA-B12, HLA-DR7, HLA-B44, and HLA A*11:01.

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 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.

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.

Implementation of Pharmacogenomic Information on Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

Drug-related Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are rare but severe adverse drug reactions, termed as idiosyncratic reactions; however, predicting their onset remains challenging. Pharmacogenomic information associated with SJS/TEN has accumulated on several drugs in the last 15 years, with clinically useful information now included on drug labels in several countries/regions or guidelines of the Clinical Pharmacogenetics Implementation Consortium (CPIC) for implementation. However, label information might be different among countries. This mini-review summarizes pharmacogenomic information on drug labels of five drugs in six countries and compared descriptions of drug labels and CPIC guidelines. Finally, we discuss future perspectives of this issue. Pharmacogenomic information on drug labels is not well-harmonized across countries/regions, but CPIC guidelines are a scientifically sound goal for future pharmacogenomic implementation.

Whole genome sequencing identifies genetic variants associated with co-trimoxazole hypersensitivity in Asians

BACKGROUND

Co-trimoxazole, a sulfonamide antibiotic, is used to treat a variety of infections worldwide, and it remains a common first-line medicine for prophylaxis against Pneumocystis jiroveci pneumonia. However, it can cause severe cutaneous adverse reaction (SCAR), including Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reaction with eosinophilia and systemic symptoms. The pathomechanism of co-trimoxazole-induced SCAR remains unclear.

OBJECTIVE

We aimed to investigate the genetic predisposition of co-trimoxazole-induced SCAR.

METHODS

We conducted a multicountry case-control association study that included 151 patients with of co-trimoxazole-induced SCAR and 4631 population controls from Taiwan, Thailand, and Malaysia, as well as 138 tolerant controls from Taiwan. Whole-genome sequencing was performed for the patients and population controls from Taiwan; it further validated the results from Thailand and Malaysia.

RESULTS

The whole-genome sequencing study (43 case patients vs 507 controls) discovered that the single-nucleotide polymorphism rs41554616, which is located between the HLA-B and MICA loci, had the strongest association with co-trimoxazole-induced SCAR (P = 8.2 × 10^-9; odds ratio [OR] = 7.7). There were weak associations of variants in co-trimoxazole-related metabolizing enzymes (CYP2D6, GSTP1, GCLC, N-acetyltransferase [NAT2], and CYP2C8). A replication study using HLA genotyping revealed that HLA-B∗13:01 was strongly associated with co-trimoxazole-induced SCAR (the combined sample comprised 91 case patients vs 2545 controls [P = 7.2 × 10^-21; OR = 8.7]). A strong HLA association was also observed in the case patients from Thailand (P = 3.2 × 10^-5; OR = 3.6) and Malaysia (P = .002; OR = 12.8), respectively. A meta-analysis and phenotype stratification study further indicated a strong association between HLA-B∗13:01 and co-trimoxazole-induced drug reaction with eosinophilia and systemic symptoms (P = 4.2 × 10^-23; OR = 40.1).

CONCLUSION

This study identified HLA-B∗13:01 as an important genetic factor associated with co-trimoxazole-induced SCAR in Asians.