TNFalpha promoter region gene polymorphisms in carbamazepine-hypersensitive patients

Drug Allergy Mimics

When approaching a case of apparent drug allergy, the consulting clinician should consider a broad differential diagnosis. This article presents a series of cases that could be commonly referred to an allergist for assessment as "drug allergy," however, a real diagnosis exists that mandates a different diagnostic and treatment strategy, including a case of inducible laryngeal obstruction, multiple drug intolerance syndrome, viral rash, seizure due to metastatic malignancy, and hemophagocytic lymphohistiocytosis initially diagnosed as drug reaction and eosinophilia with systemic symptoms. The initial misdiagnoses of these patients delayed or interfered with their medical care, emphasizing the importance of accurate diagnoses for the benefit of our patients.

HLA Allele-Restricted Immune-Mediated Adverse Drug Reactions: Framework for Genetic Prediction

Human leukocyte antigen (HLA) is a hallmark genetic marker for the prediction of certain immune-mediated adverse drug reactions (ADRs). Numerous basic and clinical research studies have provided the evidence base to push forward the clinical implementation of HLA testing for the prevention of such ADRs in susceptible patients. This review explores current translational progress in using HLA as a key susceptibility factor for immune ADRs and highlights gaps in our knowledge. Furthermore, relevant findings of HLA-mediated drug-specific T cell activation are covered, focusing on cellular approaches to link genetic associations to drug-HLA binding as a complementary approach to understand disease pathogenesis. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Successful mepolizumab treatment for DRESS-induced refractory eosinophilic myocarditis and concurrent thyroiditis

Drug reaction with eosinophilia and systemic symptoms (DRESS) is a potentially life-threatening adverse drug reaction with a mortality rate of 10%. Interstitial nephritis, pneumonitis, myocarditis, meningitis, thyroiditis and pancreatitis are major causes of morbidity and mortality in this syndrome. Cessation of offending medication is paramount. There is paucity in high quality prospective studies guiding the treatment of DRESS, and there are no published therapeutic clinical trials in the treatment of corticosteroid refractory hypersensitivity myocarditis. The authors present a unique case of ciprofloxacin-induced DRESS with concurrent thyroiditis and refractory eosinophilic myocarditis that required mepolizumab and multiple immunosuppressants for successful treatment.

Recognition and Management of Severe Cutaneous Adverse Drug Reactions (Including Drug Reaction with Eosinophilia and Systemic Symptoms, Stevens-Johnson Syndrome, and Toxic Epidermal Necrolysis)

Severe cutaneous adverse reactions to medications (SCARs) include drug reaction with eosinophilia and systemic symptoms, Stevens-Johnson syndrome, toxic epidermal necrolysis, and acute generalized exanthematous pustulosis. They are all non-immunoglobulin E mediated hypersensitivity reaction patterns, distinguished from simple cutaneous drug eruptions by immunologic pathogenesis and internal organ involvement. Herein the clinical features, diagnostic workup, and management considerations are presented for each of these major SCARs.

Genetic variants associated with T cell-mediated cutaneous adverse drug reactions: A PRISMA-compliant systematic review-An EAACI position paper

Drug hypersensitivity reactions (DHRs) are associated with high global morbidity and mortality. Cutaneous T cell-mediated reactions classically occur more than 6 hours after drug administration and include life-threatening conditions such as toxic epidermal necrolysis, Stevens-Johnson syndrome, and hypersensitivity syndrome. Over the last 20 years, significant advances have been made in our understanding of the pathogenesis of DHRs with the identification of human leukocyte antigens as predisposing factors. This has led to the development of pharmacogenetic screening tests, such as HLA-B*57:01 in abacavir therapy, which has successfully reduced the incidence of abacavir hypersensitivity reactions. We have completed a PRISMA-compliant systematic review to identify genetic associations that have been reported in DHRs. In total, 105 studies (5554 cases and 123 548 controls) have been included in the review reporting genetic associations with carbamazepine (n = 31), other aromatic antiepileptic drugs (n = 24), abacavir (n = 11), nevirapine (n = 14), trimethoprim-sulfamethoxazole (n = 11), dapsone (n = 4), allopurinol (n = 10), and other drugs (n = 5). The most commonly reported genetic variants associated with DHRs are located in human leukocyte antigen genes and genes involved in drug metabolism pathways. Increasing our understanding of genetic variants that contribute to DHRs will allow us to improve diagnosis, develop new treatments, and predict and prevent DHRs in the future.

Human leukocyte antigen-associated severe cutaneous adverse drug reactions: from bedside to bench and beyond

Despite their being uncommon, severe cutaneous adverse drug reactions (SCARs) result in a very great burden of disease. These reactions not only carry with them a high mortality (10%-50%) and high morbidity (60%) with severe ocular complications, alopecia, oral and dental complications and development of autoimmune diseases, but also create a substantial economic burden for patients' families and society. SCARs are, therefore, an important medical problem needing a solution in many countries, especially in Asia. The clinical spectrum of SCARs comprises Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS (drug rash with eosinophilia and systemic symptoms) (also known as drug hypersensitivity syndrome or drug-induced hypersensitivity syndrome) and acute generalised exanthematous pustulosis. Recent crucial advances in determining genetic susceptibility and understanding how T cells recognise certain medications or their metabolites via the major histocompatibility complex and the effects of cofactors, have led to the implementation of cost-effective screening programs enabling prevention in a number of countries, and to further understanding of the patho-mechanisms involved in SCARs and their significance. In this review, we document comprehensively the journey of SCARs from bedside to bench and outline future perspectives in SCARs research.

[Pathogenic Mechanism and Diagnostic Testing for Drug Allergies]

　Three stages of the pathogenic mechanism of drug allergies can be considered: antigen formation, immune reaction and inflammation/disorder reaction. Drugs are thought to form 4 types of antigens: drug only, polymers, drug-carrier conjugates, and metabolite-carrier complexes. Antigens are recognized by B cell receptors and T cell receptors. Helper T cells (Th) are differentiated into four subsets, namely, Th1, Th2, Th17 and regulatory T cells (Treg). Th1 produces interleukin (IL)-2 and interferon (IFN)-γ, and activates macrophages and cytotoxic T cells (Tc). Macrophages induce type IV allergies, and Tc lead to serious type IV allergies. On the other hand, Th2 produces IL-4, IL-5, and IL-6, etc., and activates B cells. B cells produce IgE antibodies, and the IgE antibody affects mast cells and induces type I allergies. Activated eosinophil leads to the chronic state of type I allergy. Diagnostic testing for allergenic drugs is necessary for patients with drug allergies. Because in vivo diagnostic tests for allergenic drugs are associated with a risk and burden to the patient, in vitro allergy tests are recommended to identify allergenic drugs. In allergy tests performed in vitro, cytological tests are more effective than serological tests, and the leukocyte migration test (LMT) presently has the highest efficacy. An LMT-chamber is better than LMT-agarose in terms of usability and sensitivity, and it can detect about 80% of allergenic drugs.

Pharmacogenetics of adverse reactions to antiepileptic drugs

INTRODUCTION

Adverse drug reactions (ADRs) are a major public health concern and a leading cause of morbidity and mortality in the world. In the case of antiepileptic drugs (AEDs), ADRs constitute a barrier to successful treatment since they decrease treatment adherence and impact patients' quality of life of patients. Pharmacogenetics aims to identify genetic polymorphisms associated with drug safety. This article presents a review of genes coding for drug metabolising enzymes and drug transporters, and HLA system genes that have been linked to AED-induced ADRs.

DEVELOPMENT

To date, several genetic variations associated with drug safety have been reported: CYP2C9*2 and *3 alleles, which code for enzymes with decreased activity, have been linked to phenytoin (PHT)-induced neurotoxicity; GSTM1 null alleles with hepatotoxicity induced by carbamazepine (CBZ) and valproic acid (VPA); EPHX1 polymorphisms with teratogenesis; ABCC2 genetic variations with CBZ- and VPA-induced neurological ADRs; and HLA alleles (e.g. HLA-B*15:02, -A*31:01, -B*15:11, -C*08:01) with cutaneous ADRs.

CONCLUSIONS

Published findings show that there are ADRs with a pharmacogenetic basis and a high interethnic variability, which indicates a need for future studies in different populations to gather more useful results for larger number of patients. The search for biomarkers that would allow predicting ADRs to AEDs could improve pharmacotherapy for epilepsy.

HLA-A*02:01:01/-B*35:01:01/-C*04:01:01 haplotype associated with lamotrigine-induced maculopapular exanthema in Mexican Mestizo patients

Aim: Several HLA alleles have been associated with antiepileptic drugs (AEDs)-induced cutaneous adverse drug reactions (cADRs) in different populations; however, this has not been investigated in Mexican Mestizos (MM). Thus, the purpose of this preliminary study was to determine the association of HLA class I alleles with AED-induced cADRs in MM patients. Materials & methods: This case–control association study included 21 MM patients with phenytoin (PHT)-, carbamazepine (CBZ)-, or lamotrigine (LTG)-induced maculopapular exanthema (MPE) or Stevens–Johnson syndrome (SJS); 31 MM patients tolerant to the same AEDs; and 225 unrelated, healthy MM volunteers. HLA class I genotyping was performed. Differences in HLA allele frequencies between AED-induced cADR patients and AED-tolerant patients were assessed. Frequencies of alleles possibly associated with AED-induced cADRs in MM patients were compared with those in MM population. Results: The frequency of HLA-C*08:01 allele in PHT-induced MPE was higher than that in the PHT-tolerant group (pc = 0.0179) or in the MM population (pc < 0.0001). For the first time, HLA-A*02:01:01/-B*35:01:01/-C*04:01:01 haplotype was associated with LTG-induced MPE (pc = 0.0048 for LTG-tolerant groups and pc < 0.0001 for MM population). Conclusion: Our data suggest the HLA-A*02:01:01/-B*35:01:01/-C*04:01:01 haplotype may be a biomarker for LTG-induced MPE and the HLA-C*08:01 allele for PHT-induced MPE. We also identified HLA-A*01:01:01 and -A*31:01:02 as candidates alleles associated with CBZ-induced MPE in MM patients. However, further investigations are necessary to confirm these findings.

Original submitted 28 March 2014; Revision submitted 15 September 2014

HLA alleles and hypersensitivity to carbamazepine: an updated systematic review with meta-analysis

OBJECTIVE

A considerable heterogeneity exists in the literature on the role of different HLA alleles in carbamazepine (CBZ)-induced cutaneous adverse drug reactions (cADRs) of varying severity among diverse ethnic groups. The aim of the present study was to understand and summarize this heterogeneity and evaluate the contribution of common HLA alleles to susceptibility to cADRs in patients treated with CBZ through a meta-analysis.

MATERIALS AND METHODS

A literature search of Embase, Medline, Web of Knowledge, and Cochrane database of systematic reviews was performed up to 28 September 2013.

RESULTS

A total of 20 reports were identified as eligible studies, which included 720 CBZ-intolerant [Stevens-Johnson syndrome and toxic epidermal necrolysis (bullous lesions): n=277; hypersensitivity syndrome/maculopapular exanthema (nonbullous lesions): n=359; others: n=84], 1512 CBZ-tolerant, and 1113 normal controls. We observed HLA-A*3101 and HLA-B*1502 as risk markers and HLA-B*4001 as a protective marker for susceptibility to cADRs when comparing intolerant with tolerant patients. Stratification by clinical outcome showed HLA-B*1502 and HLA-B*1511 as risk and HLA-A*2402 as protective markers for bullous lesions in the Asians [HLA-B*1502: odds ratio (OR)=80.70; 95% confidence interval (CI)=45.62-142.77; P=1.8×10(-51); I(2)=33%, HLA-B*1511: OR=17.43; 95% CI=3.12-97.40; P=1.1×10(-3); I(2)=0%, HLA-A*2402: OR=0.27; 95% CI=0.11-0.64; P=2.7×10(-3); I(2)=0%]. Furthermore, HLA-A*3101 was observed to be a universal risk marker, irrespective of cADR type [OR (bullous lesions)=5.65; 95% CI =2.70-11.78; P=4.03×10(-6); I(2)=49%, OR (nonbullous lesions)=8.58; 95% CI=5.55-13.28; P=4.46×10(-22); I(2)=0%]. Sensitivity analysis showed HLA-B*4001 as a protective marker in Chinese population for showing bullous lesions (OR=0.14; 95% CI=0.06-0.32; P=3.2×10(-6); I(2)=0%).

CONCLUSION

In summary, our meta-analysis showed the presence of HLA alleles contributing toward risk of as well as protection against various CBZ-induced cADRs.

Hypersensitivity to antiepileptic drugs

Adverse reactions to antiepileptic drugs (AEDs) may lead to treatment failure, morbidity, and mortality. Drug hypersensitivity reactions (DHRs) are potentially fatal. AED DHRs present with a variety of clinical manifestations. The pathogenesis of AED DHRs has not been fully elucidated. Bioactivation, detoxification, covalent adduct formation, presentation to the immune system, and consequent formation of antibody and T-cell immune effectors have been suggested. This article summarizes the epidemiology, pathogenic mechanisms, risk factors, clinical features, and management of allergic reactions to the aromatic AEDs carbamazepine, phenytoin, and lamotrigine.

Fever, rash, and systemic symptoms: understanding the role of virus and HLA in severe cutaneous drug allergy

Drug hypersensitivity syndromes such as abacavir hypersensitivity and the severe cutaneous adverse drug reactions have been associated with significant short- and long-term morbidity and mortality. More recently, these immunologically mediated and previously unpredictable diseases have been shown to be associated with primarily class I but also class II HLA alleles. The case of the association of HLA-B*57:01 and abacavir hypersensitivity has created a translational roadmap for how this knowledge can be used in the clinic to prevent severe reactions. Although many hurdles exist to the widespread translation of such HLA screening approaches, our understanding of how drugs interact with the major histocompatibility complex has contributed to the discovery of new models that have provided considerable insights into the immunopathogenesis of severe cutaneous adverse drug reactions and other T-cell-mediated drug hypersensitivity syndromes. Future translation of this knowledge will facilitate the development of preclinical toxicity screening to significantly improve efficacy and safety of drug development and design.

Drug-induced liver injury from antiepileptic drugs

Drug-induced liver injury is a potential complication of innumerable medications. Most cases do not occur in a predictable, dose-dependent manner, leading to delayed recognition of a drug's hepatotoxic potential until after its release into the market. The estimated occurrence is 1 in 10,000 to 100,000 patients. However, the rates are likely higher because many cases go unrecognized owing to lack of reporting or missed diagnosis. This article reviews the most commonly associated antiepileptic drugs.

Oxcarbazepine-induced Stevens Johnson syndrome: A rare case report

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

Drug reaction with Eosinophilia and Systemic Symptoms (DRESS) / Drug-induced Hypersensitivity Syndrome (DIHS): a review of current concepts

The Drug Reaction with Eosinophilia and Systemic Symptoms syndrome, also known as Drug Induced Hypersensitivity Syndrome presents clinically as an extensive mucocutaneous rash, accompanied by fever, lymphadenopathy, hepatitis, hematologic abnormalities with eosinophilia and atypical lymphocytes, and may involve other organs with eosinophilic infiltration, causing damage to several systems, especially to the kidneys, heart, lungs, and pancreas. Recognition of this syndrome is of paramount importance, since the mortality rate is about 10% to 20%, and a specific therapy may be necessary. The pathogenesis is related to specific drugs, especially the aromatic anticonvulsants, altered immune response, sequential reactivation of herpes virus and association with HLA alleles. Early recognition of the syndrome and withdrawal of the offending drug are the most important and essential steps in the treatment of affected patients. Corticosteroids are the basis of the treatment of the syndrome, which may be associated with intravenous immunoglobulin and, in selected cases, Ganciclovir. The article reviews the current concepts involving this important manifestation of adverse drug reaction.

TNF-α genetic polymorphism -308G/A and antituberculosis drug-induced hepatitis

BACKGROUND

While the mechanisms underlying the development of drug-induced liver injury are not clear, there is evidence to suggest that tumor necrosis factor-α (TNF-α) plays an important role in drug- or drug metabolite-induced immune responses. We hypothesized that polymorphisms in the TNF-α gene are associated with anti-tuberculosis drug (ATD)-induced hepatitis.

METHODS

Patients who suffered from ATD-induced hepatitis were enrolled in the study. ATD-induced hepatitis was defined as an increase in liver transaminase levels that were more than three times the upper limit of normal. ATD-tolerant patients were used as a control. Patients were treated with first line ATD therapies including isoniazid, rifampicin, ethambutol, and pyrazinamide. We compared the genotype frequencies of the TNF-α polymorphism -308G/A in 77 patients with ATD-induced hepatitis and 229 ATD-tolerant patients.

RESULTS

The frequency of carrying the variant allele (AG or AA) was significantly higher in patients with ATD-induced hepatitis compared with ATD-tolerant patients [26.0% vs. 15.3%, P = 0.034, OR (95% CI) = 1.94 (1.04–3.64)] and the frequency of the A allele was significantly different between the two groups [0.143 vs. 0.079, P = 0.018, OR (95% CI) = 1.95 (1.11–3.44)].

CONCLUSION

These results reveal that the TNF-α genetic polymorphism -308G/A is significantly associated with ATD-induced hepatitis. This genetic variant may be a risk factor for ATD-induced hepatitis in individuals from Korea.

Drug hypersensitivity and human leukocyte antigens of the major histocompatibility complex

The human leukocyte antigen (HLA) genes are the most polymorphic in the human genome and are critical in regulating specific immunity, hence their historical discovery as "immune response" genes. HLA allotypes are also implicated in unwanted immune reactions, including drug hypersensitivity syndrome, in which small therapeutic drugs interact with antigenic peptides to drive T cell responses restricted by host HLA. Abacavir, allo-purinol, and carbamazepine are three commonly used drugs that cause a T cell-mediated hypersensitivity that is HLA linked, with each drug exhibiting striking specificity for presentation by defined HLA allotypes. Recent findings have begun to unearth the mechanistic basis for these HLA associations, and here we review recent advances in the field of HLA-associated drug hypersensitivities.

Pharmacogenetic screening of carbamazepine-induced severe cutaneous allergic reactions

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

HLA-A*3101 and carbamazepine-induced hypersensitivity reactions in Europeans

BACKGROUND

Carbamazepine causes various forms of hypersensitivity reactions, ranging from maculopapular exanthema to severe blistering reactions. The HLA-B*1502 allele has been shown to be strongly correlated with carbamazepine-induced Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS-TEN) in the Han Chinese and other Asian populations but not in European populations.

METHODS

We performed a genomewide association study of samples obtained from 22 subjects with carbamazepine-induced hypersensitivity syndrome, 43 subjects with carbamazepine-induced maculopapular exanthema, and 3987 control subjects, all of European descent. We tested for an association between disease and HLA alleles through proxy single-nucleotide polymorphisms and imputation, confirming associations by high-resolution sequence-based HLA typing. We replicated the associations in samples from 145 subjects with carbamazepine-induced hypersensitivity reactions.

RESULTS

The HLA-A*3101 allele, which has a prevalence of 2 to 5% in Northern European populations, was significantly associated with the hypersensitivity syndrome (P=3.5×10(-8)). An independent genomewide association study of samples from subjects with maculopapular exanthema also showed an association with the HLA-A*3101 allele (P=1.1×10(-6)). Follow-up genotyping confirmed the variant as a risk factor for the hypersensitivity syndrome (odds ratio, 12.41; 95% confidence interval [CI], 1.27 to 121.03), maculopapular exanthema (odds ratio, 8.33; 95% CI, 3.59 to 19.36), and SJS-TEN (odds ratio, 25.93; 95% CI, 4.93 to 116.18).

CONCLUSIONS

The presence of the HLA-A*3101 allele was associated with carbamazepine-induced hypersensitivity reactions among subjects of Northern European ancestry. The presence of the allele increased the risk from 5.0% to 26.0%, whereas its absence reduced the risk from 5.0% to 3.8%. (Funded by the U.K. Department of Health and others.).

Cutaneous drug hypersensitivity: immunological and genetic perspective

Drug hypersensitivity is an unpredictable, immunologically mediated adverse reaction, clustered in a genetically predisposed individual. The role of "hapten concept" in immune sensitization has recently been contested by the "pharmacological interaction" hypothesis. After completion of the "human genome project" and with the availability of high-resolution genotyping, genetic susceptibility to hypersensitivity for certain drugs has been proved beyond doubt though the trend is ethnicity and phenotype dependent. Application of this newly acquired knowledge may reduce or abolish the morbidity and mortality associated with cutaneous drug hypersensitivity.

Pharmacogenetics of drug hypersensitivity

Drug hypersensitivity reactions and severe cutaneous adverse drug reactions, such as Stevens-Johnson syndrome and toxic epidermal necrolysis, are examples of serious adverse drug reactions mediated through a combination of metabolic and immunological mechanisms that could traditionally not have been predicted based on the pharmacological characteristics of the drug alone. The discovery of new associations between these syndromes and specific HLA has created the promise that risk for these reactions could be predicted through pharmacogenetic screening, thereby avoiding serious morbidity and mortality associated with these types of drug reactions. Despite this, several hurdles exist in the translation of these associations into pharmacogenetic tests that could be routinely used in the clinical setting. HLA-B*5701 screening to prevent abacavir hypersensitivity syndrome is an example of a test now in widespread routine clinical use in the developed world.

Personalized medicine for HLA-associated drug-hypersensitivity reactions

Multiple genetic and nongenetic factors can modify the action of a drug, resulting in varied responses to a particular drug across different individuals. Personalized medicine incorporates the comprehensive knowledge of these factors to facilitate the selection of optimal therapy, reduce adverse drug reactions, increase patient compliance and increase the efficiency of therapy. Pharmacogenomics, which integrates the knowledge of an individual’s genetic make-up for diagnostic decisions or therapeutic interventions is closely linked to personalized medicine, and is being increasingly used to prevent adverse drug reactions. There are various reports on genetic associations between particular HLA allotypes and drug hypersensitivities and the strongest associations reported thus far, are with the reverse transcriptase inhibitor, abacavir and HLA-B*5701, the gout prophylactic allopurinol and HLA-B*5801 and the antiepileptic carbamazepine and B*1502, providing a defined disease trigger and suggesting a general mechanism for these associations. Recognizing the strong HLA association, the US FDA has recommended genetic testing before starting abacavir and carbamazepine therapies. To incorporate HLA testing for other drug hypersensitivities and life-threatening reactions it is essential first to establish clear HLA associations, and second, to understand the immune-mechanism by which these drugs induce HLA-linked hypersensitivity. The latter will provide insight into the pathologic mechanisms of drug allergy allowing rational immunotherapy for these life-threatening reactions and the development of alternative drug therapies for hypersensitive patients.

Gene polymorphisms and their role in epilepsy treatment and prognosis

The human genome carries an enormous number of genetic variants, many of them of functional consequence. In epilepsy, they are likely to be involved in drug-specific treatment efficacy, unwanted or even toxic drug reactions, teratogenic risks in pregnancy as well as in the long-term prognosis of patients with epilepsy. As in many other disorders with a complex genetic background, the associated genetic variants that could be verified successfully in replication studies are still only a few. However, new techniques and improved research strategies are likely to increase their number in the foreseeable future, although at a much slower pace as initially expected.

Association between HLA-B*1502 and carbamazepine-induced severe cutaneous adverse drug reactions in a Thai population

Carbamazepine (CBZ) has been reported as the most common culprit drug for Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) in several Asian countries including Thailand. A strong association between HLA-B*1502 and CBZ-induced SJS/TEN has been reported in Han Chinese but not in Caucasian and Japanese populations. A case-control study was conducted to determine whether HLA-B*1502 is a valid pharmacogenetic test for SJS/TEN caused by CBZ in a Thai population. Among 42 CBZ-induced patients with SJS/TEN, 37 (88.10%) patients carried the HLA-B*1502 while only 5 (11.90%) of the CBZ-tolerant controls had this allele. The risk of CBZ-induced SJS/TEN was significantly higher in the patients with HLA-B*1502, with an odds ratio (OR) of 54.76 [95% confidence interval (CI) 14.62-205.13, p = 2.89 x 10(-12)]. The sensitivity and specificity of HLA-B*1502 for prediction of CBZ-induced SJS/TEN were 88.10%. By assuming a 0.27% as a prevalence rate of CBZ-induced SJS/TEN in a Thai population, the positive predictive value (PPV) and negative predictive value (NPV) of the HLA-B*1502 were 1.92% and 99.96%. Results from this study suggest that HLA-B*1502 may be a useful pharmacogenetic test for screening Thai individuals who may be at risk for CBZ-induced SJS and TEN.

The role of cytokines in the mechanism of adverse drug reactions

Cytokines are thought to play a role in acute and/or immune-mediated adverse drug reactions (ADRs) due to their ability to regulate the innate and adaptive immune systems. This role is highly complex owing to the pluripotent nature of cytokines, which enables the same cytokine to play multiple roles depending on target organ(s) involved. As a result, the discussion of cytokine involvement in ADRs is organized according to target organ(s); specifically, ADRs targeting skin and liver, as well as ADRs targeting multiple organs, such as drug-induced autoimmunity and infusion-related reactions. In addition to discussing the mechanism(s) by which cytokines contribute to the initiation, propagation, and resolution of ADRs, we also discuss the usefulness and limitations of current methodologies available to conduct such mechanistic studies. While animal models appear to hold the most promise for uncovering additional mechanisms, this field is plagued by a lack of good animal models and, as a result, the mechanism of cytokine involvement in ADRs is often studied using less informative in vitro studies. The recent formation of the Drug-Induced Liver Injury Network, whose goal is collect thousands of samples from drug-induced liver injury patients, has enormous potential to advance knowledge in this field, by enabling large-scale cytokine polymorphism studies. In conclusion, we discuss how further advances in this field could be of significant benefit to patients in terms of preventing, predicting, and treating ADRs.

Pharmacogenetics of idiosyncratic adverse drug reactions

Idiosyncratic adverse drug reactions are unpredictable and thought to have an underlying genetic etiology. With the completion of the human genome and HapMap projects, together with the rapid advances in genotyping technologies, we have unprecedented capabilities in identifying genetic predisposing factors for these relatively rare, but serious, reactions. The main roadblock to this is the lack of sufficient numbers of well-characterized samples from patients with such reactions. This is now beginning to be solved through the formation of international consortia, including developing novel ways of identifying and recruiting patients affected by these reactions, both prospectively and retrospectively. This has been led by the research on abacavir hypersensitivity - its association with HLA-B*5701 forms the gold standard of how we need to identify associations and implement them in clinical practice. Strong genetic predisposing factors have also been identified for hypersensitivity reactions such as are associated with carbamazepine, allopurinol, flucloxacillin, and statin-induced myopathy. However, for most other idiosyncratic adverse drug reactions, the genetic effect sizes have been low to moderate, although this may partly be due to the fact that only small numbers have been investigated and limited genotyping strategies have been utilized. It may also indicate that genetic predisposition will be dependent on multiple genes, with complex interactions with environmental factors. Irrespective of the strength of the genetic associations identified with individual idiosyncratic adverse drug reactions, it is important to undertake functional investigations to provide insights into the mechanism(s) of how the drug interacts with the gene variant to lead to a phenotype, which can take a multitude of clinical forms with variable severity. Such investigations will be essential in preventing the burden caused by idiosyncratic reactions, both in healthcare and in industry.

TNF, LTA, HSPA1L and HLA-DR gene polymorphisms in HIV-positive patients with hypersensitivity to cotrimoxazole

AIMS

Sulfamethoxazole in combination with trimethoprim (cotrimoxazole) is used for prophylaxis and treatment of several opportunistic infections in HIV-infected patients. It is associated with a high incidence of hypersensitivity reactions, which is thought to have an immune basis. Genetic polymorphisms in MHC are known to predispose to hypersensitivity reactions to a structurally diverse group of drugs in HIV-positive patients. The aim of the study was to determine whether functional polymorphisms in TNF, LTA, HSPA1L and HLA-DRB1 genes influence the risk of cotrimoxazole hypersensitivity in HIV-infected patients.

METHODS

We genotyped 136 HIV-positive patients with (n = 53) and without (n = 83) cotrimoxazole hypersensitivity using a combination of PCR-based techniques, including PCR-restriction fragment length polymorphisms, PCR-sequence specific oligonucleotides and real-time PCR. Genotypes and the haplotype frequencies were analyzed using the chi(2) test in the Haploview and CLUMP programs.

RESULTS

No statistically significant difference in SNP or haplotype frequencies were found in HIV-infected sulfamethoxazole hypersensitive patients compared with controls.

CONCLUSION

Our data show that MHC polymorphisms are not major predisposing factors for cotrimoxazole hypersensitivity, although we cannot exclude a minor contribution. An environmental factor (i.e., HIV infection) seems to predominate over any of the genetic factors so far investigated in increasing the risk of cotrimoxazole hypersensitivity.

Oxcarbazepine-induced Stevens-Johnson syndrome: a case report

Although carbamazepine (CBZ) is the most common cause of Stevens-Johnson syndrome (SJS), a new anticonvulsant, oxcarbazepine, which is structurally related to carbamazepine, has been shown to induce SJS, although extremely rarely. Recently, a strong association was found between human leukocyte antigen (HLA) B*1502 and CBZ-induced SJS/TEN in a Han Chinese population. Here, we report a case with SJS, which was induced by oxcarbazepine. HLA genotyping in the patient showed HLA-B*1518/B*4001. HLA-B*1518 is a HLA-B15 variant. The genetic significance of HLA-B*1518 in association with oxcarbazepine-induced SJS needs to be further studied.

Drug-induced hypersensitivity syndrome: clinical and biologic disease patterns in 24 patients

Drug-induced hypersensitivity syndrome (DIHS), also called drug rash with eosinophilia and systemic symptoms (DRESS), is a severe reaction usually characterized by fever, rash, and multiorgan failure, occurring 1-8 weeks after drug introduction. It is an immune-mediated reaction involving macrophage and T-lymphocyte activation and cytokine release, although no consensus has been reached as to its etiology. The skin, hematopoietic system, and liver are frequently involved. DIHS can mimic severe sepsis, viral infection, adult-onset Still disease (AOSD), or lymphoproliferation.We describe 24 consecutive patients with DIHS who were hospitalized between September 2004 and March 2008. Criteria for inclusion in this observational study were suspected drug reaction, eosinophilia >or=500/microL and/or atypical lymphocytes, involvement of at least 2 organs (skin being 1 of them), with suggestive chronology and exclusion of other diagnoses. Our cohort of 12 women and 12 men had a median age of 49 years (range, 22-82 yr), and 11 had skin phototype V or VI. Patients with mild or no rash were immunocompromised (7/24)- defined as treatment with prednisone (>or=10 mg/d) and another immunosuppressant drug, or human immunodeficiency virus infection. All patients were febrile (>38 degrees C), 14 had localized or generalized edema, 7 had pharyngitis, 8 had lymphadenopathy, 22 had hepatitis, 4 had nephritis, 2 had noninfectious and nonlithiasic angiocholitis or cholecystitis. Ten patients were hypotensive, 5 of whom had associated laboratory signs and/or imaging findings suggestive of acute myocardial dysfunction. Half of the patients had hemogram abnormalities, including eosinophilia. Nine DIHS patients fulfilled the Fautrel criteria for AOSD diagnosis, including glycosylated ferritin <20% in 4/11, with or without laboratory characteristics of hemophagocytosis. Twenty DIHS episodes occurred during the less sunny months of October to March.We determined 25-hydroxyvitamin D3 (25[OH]D3) levels in 18 patients and found that 9 patients had vitamin D deficiency (<25 nmol/L or <10 microg/L) and 5 had vitamin D insufficiency (25-50 nmol/L). Moreover, 25(OH)D3 levels were inversely correlated with ferritin values. After culprit-drug withdrawal, outcomes were favorable for all patients, including those with cardiac abnormalities under slow tapering of glucocorticoids.We recommend looking for the frequent but underdiagnosed hypersensitivity myocarditis with noninvasive diagnostic tools, such as N-terminal probrain natriuretic peptide, and promptly withdrawing the culprit drug and starting glucocorticoids. Vitamin D deficiency might be a DIHS risk or severity factor, especially for patients with high skin phototype and during the winter. Because DIHS clinical and laboratory patterns share similarities with AOSD and hemophagocytosis, DIHS should be included in their differential diagnoses.

Association between TNFA-308 G/A polymorphism and sensitization to para-phenylenediamine: a case-control study

BACKGROUND

Para-phenylenediamine (PPD) and related chemicals are common contact sensitizers, frequently causing allergic contact dermatitis (ACD). The cytokine tumor necrosis factor-alpha (TNF-alpha) plays a key role in contact sensitization.

METHODS

In this case-control study, we evaluated the distribution of variations in the regulatory region of the gene for TNF-alpha (TNFA-308 G/A) in 181 Caucasian individuals with a history of ACD and sensitization to PPD and 161 individuals with no history of sensitization to PPD.

RESULTS

The frequency of GA or AA TNFA genotypes was significantly higher in individuals sensitized to PPD than in age- and gender-matched controls giving an odds ratio (OR) of 2.16 (95% confidence interval, CI: 1.35-3.47; P = 0.0016). This relation was even more pronounced when restricting cases to females over 45 years (OR = 3.71; 95% CI: 1.65-8.31; P = 0.0017) vs younger females (less than or equal to 45 years; OR = 2.41; 95% CI: 1.03-5.65; P = 0.044) or males (OR = 1.05; 95% CI: 0.449-2.47; P = 1.0). In addition, a logistic regression model revealed a significant effect for TNFA-308 AA and AG vs GG genotype (point estimate = 2.152; 95% Wald CI: 1.332-3.477).

CONCLUSIONS

These findings suggest a possible role for the TNFA-308 genetic polymorphism as a susceptibility factor for chemically induced ACD.

Pharmacogenetics in epilepsy treatment: sense or nonsense?

Epilepsy is the most common serious chronic neurological disorder. Treatment consists mainly of antiepileptic drugs (AEDs), with more than 15 different molecules available. However, AED treatment is often problematic because of unpredictability of drug response, adverse drug reactions and optimal dosing in individual patients. Moreover, up to one in three patients with epilepsy are refractory to currently available AEDs. Pharmacogenetic studies explore the contribution of genetic variants to interindividual differences in drug response. An increasing number of pharmacogenetic association studies in epilepsy are being reported. Nevertheless, at present only one association is firmly established, namely that of the HLA-B*1502 allele with severe cutaneous adverse drug reactions on carbamazepine therapy in the Han Chinese population. It is likely that large collaborations looking at multiple genes encoding entire drug pathways, or even the entire human genome, together with new pharmacogenetic strategies will result in the discovery of other genetic variants involved in AED response. Although several challenges remain, it is hoped that, ultimately, these findings will lead to the development of predictive tests, resulting in a more efficacious and safer AED treatment, and to the development of new AEDs with novel mechanisms of action, particularly aimed at patients with drug-refractory epilepsy.