Pharmacogenetic screening of carbamazepine-induced severe cutaneous allergic reactions

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.

Awareness of HLA-B* 15:02 screening in trigeminal neuralgia and the gene screening policy among dentists in Southern Thailand

OBJECTIVES

To determine the factors associated with public hospital dentists' awareness of HLA-B*15:02 screening in trigeminal neuralgia (TN) and the national gene screening policy in Thailand.

METHODS

Cross-sectional study. A validated questionnaire was distributed to public hospital dentists with at least 1 year of practice in Southern Thailand (n = 760) to assess their knowledge of TN, carbamazepine (CBZ) use, awareness of HLA-B*15:02 screening, and the gene screening policy.

RESULTS

A total of 385 dentists participated (50.7% response rate); 81.3% of respondents were aware of HLA-B*15:02 screening. However, 18.7% of dentists were not aware of the importance of gene testing. Furthermore, dentists who were aware of gene screening had significantly better knowledge of TN diagnosis and CBZ use than "unaware" dentists. Awareness of HLA-B*15:02 screening was also significantly associated with dental specialty. Moreover, 80.5% of respondents were not aware of the gene screening policy. The primary problems related to the policy were its inefficient publication, poor implementation, and lack of clinical practice guidelines (CPGs) to encourage dentists to follow the policy and prescribe gene tests.

CONCLUSION

While most hospital dentists were aware of the necessity of HLA-B*15:02 screening prior to prescribing CBZ in TN, the majority were unaware of the national gene screening policy. Dental specialty and knowledge were associated with awareness of HLA-B*15:02 screening.

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.

Genetic Markers for Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis in the Asian Indian Population: Implications on Prevention

This review attempts to collate all the studies performed in India or comprising a population originating from India and to find out if there is an association between the HLA (human leucocyte antigen) type of individual and development of Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) subsequent to medication use. The authors performed a PubMed search of all articles published in English from 2009 to 2019 for articles that studied HLA type in patients who developed SJS/TEN after intake of a specific drug in the Asian Indian population or in individuals of Asian Indian origin. The selection criteria were satisfied by a total of 11 studies that reported HLA associations with specific drugs, which induced SJS/TEN, mainly anti-epileptic drugs, and cold medicine/non-steroidal anti-inflammatory drugs. These studies involved a small number of patients, and hence, there is limited evidence to conclude if these associations can be extrapolated to a larger population of the same ethnicity. Similar multi-center studies need to be conducted with a larger sample size to confirm these associations. This would have implications in policy making and for understanding the potential of using genetic markers as a screening tool before prescribing a drug to a patient, which might make them susceptible to developing a potentially life-threatening disease such as SJS/TEN. This is possibly the only mode of primary prevention for this potentially fatal severe cutaneous adverse drug reaction.

Genetic susceptibilities and prediction modeling of carbamazepine and allopurinol-induced severe cutaneous adverse reactions in Vietnamese

Aims: To determine genetic susceptibility markers for carbamazepine (CBZ) and allopurinol-induced severe cutaneous adverse reactions (SCARs) in Vietnamese. Methods: A case-control study was performed involving 122 patients with CBZ or allopurinol-induced SCARs and 120 drug tolerant controls. Results: HLA-B*58:01 was strongly associated with allopurinol-induced SCARs and strongly correlated with SNP rs9263726. HLA-B*15:02 was associated with CBZ-induced Stevens-Johnson syndrome/toxic epidermal necrolysis but not with drug-induced hypersensitivity syndrome/drug rash with eosinophilia and systemic symptoms. No association was found between HLA-A*31:01 and CBZ-induced SCARs. HLA-B*58:01 and rs3909184 allele A with renal insufficiency were shown to increase the risk of allopurinol-induced SCARs. Conclusion: HLA-B*58:01 and HLA-B*15:02 confer susceptibility to allopurinol-induced SCARs and CBZ-induced SJS/TEN in Vietnamese. SNP rs9263726 can be used as a surrogate marker in identifying HLA-B*58:01.

Rashes and other hypersensitivity reactions associated with antiepileptic drugs: A review of current literature

This article provides an overview of the pathogenesis and risk factors associated with antiepileptic drug (AED) hypersensitivity reactions, provides prescribing guidelines that may minimize the risk of antiepileptic induced rashes, and discusses treatment options for rashes. Articles indexed in PubMed, Science Citation, and Google Scholar (January 1946-March 2019) were systematic searched using the following key terms: hypersensitivity, rash, antiepileptic, epilepsy, cross-sensitivity, desensitization, patch testing and supplemented with our clinical experiences. Additional references were identified from a review of literature citations. AEDs are associated with cutaneous adverse reactions. Aromatic AEDs and higher titration rates are associated with increased risk of hypersensitivity reaction. Patient characteristics, underlying health conditions, and genetic variations may increase the likelihood of a hypersensitivity reaction. Once a hypersensitivity reaction occurs, the likelihood of cross sensitivity to another AED increases, especially among other aromatic AEDs. Withdrawal of the causal agent and initiation of a lower risk agent usually leads to resolution of symptoms. Desensitization protocols may be an option for patients whose seizures only respond to the AED causing the rash.

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.

Drug-induced Stevens-Johnson syndrome and toxic epidermal necrolysis in vietnamese spontaneous adverse drug reaction database: A subgroup approach to disproportionality analysis

WHAT IS KNOWN AND OBJECTIVE

Despite the numerous studies investigating drug-induced Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), the understanding and quantitative data in developing countries remain limited. The study aimed to describe and quantify the drug-related risk of SJS/TEN in a resource-limited context using the Vietnamese spontaneous reporting database (VSRD) of adverse drug reactions.

METHODS

Spontaneous reports relating to medium- and late-onset severe cutaneous adverse reactions (MLOSCAR) and SJS/TEN recorded in the VSRD from 2010 to 2015 were retrospectively analysed. The demographic characteristics and drug information were described and compared between SJS/TEN and other MLOSCAR reports. The drug-induced SJS/TEN signals were estimated using subgrouped disproportionality analysis with calculation of the reporting odds ratio (ROR) and the respective 95% confidence interval (CI).

RESULTS

The VSRD received 2,849 MLOSCAR reports, 136 of which focus on SJS/TEN over a 6-year period. About 60% of SJS/TEN patients were male, and the majority of them were adults (mean age 42.5 ± 22.9). Up to 91.8% of drugs induced SJS/TEN within 1-28 days, and 45% SJS/TEN cases were evaluated as life-threatening. Positive signals were generated with carbamazepine (n = 25, ROR [95% CI] = 11.99 [7.07-19.92]), allopurinol (n = 15, ROR [95% CI] = 4.2 [2.20-7.59]), traditional/herbal medicines (n = 7, ROR [95% CI] = 2.76 [1.12-5.86]), colchicine (n = 4, ROR [95% CI] = 6.22 [1.69-18.72]), valproic acid (n = 3, ROR [95% CI] = 8.71 [1.89-30.19]) and meloxicam (n = 3, ROR [95% CI] = 7.09 [1.55-24.29]), which are well known for SJS/TEN. Cefixime (n = 5, ROR [95% CI] = 3.34 [1.13-8.00]) and paracetamol (n = 22, ROR [95% CI] = 5.23 [3.10-8.49]) also generated positive signals despite their popularity in Vietnam.

WHAT IS NEW AND CONCLUSION

This first Vietnamese population-based study has highlighted original characteristics and signals of drug-induced SJS/TEN, which are relatively consistent with other worldwide data and typical for a developing country.

Epilepsy in Asia: Disease burden, management barriers, and challenges

This article reviews the burden of epilepsy in Asia, the challenges faced by people with epilepsy, and the management of epilepsy. Comparison is made with other parts of the world. For this narrative review, data were collected using specified search criteria. Articles investigating the epidemiology of epilepsy, diagnosis, comorbidities and associated mortality, stigmatization, and treatment were included. Epilepsy is a global health care issue affecting up to 70 million people worldwide. Nearly 80% of people with epilepsy live in low- and middle-income countries with limited resources. People with epilepsy are prone to physical and psychological comorbidities, including anxiety and depression, which can negatively impact their quality of life. Furthermore, people with epilepsy are at higher risk of premature death than people without epilepsy. Discrimination or stigmatization of people with epilepsy is common in Asia and can affect their education, work, and marriage opportunities. Access to epilepsy treatment varies throughout Asia. Although highly advanced treatment is available in some countries, up to 90% of people with epilepsy are not adequately treated or are not treated with conventional antiepileptic therapy in resource-limited countries. People in remote areas often do not receive any epilepsy care. First-generation antiepileptic drugs (AEDs) are available, but usually only in urban areas, and second-generation AEDs are not available in all countries. Newer AEDs tend to have more favorable safety profiles than first-generation AEDs and provide options to tailor therapy for individual patients, especially those with comorbidities. Active epilepsy surgery centers are present in some countries, although epilepsy surgery is often underutilized given the number of patients who could benefit. Further epidemiologic research is needed to provide accurate epilepsy data across the Asian region. Coordinated action is warranted to improve access to treatment and care.

Drug-Induced Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis Call for Optimum Patient Stratification and Theranostics via Pharmacogenomics

The Global Genomic Medicine Collaborative, a multinational coalition of genomic and policy experts working to implement genomics in clinical care, considers pharmacogenomics to be among the first areas in genomic medicine that can provide guidance in routine clinical practice, by linking genetic variation and drug response. Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe life-threatening reactions to medications with a high incidence worldwide. Genomic screening prior to drug administration is a key opportunity and potential paradigm for using genomic medicine to reduce morbidity and mortality and ultimately eliminate one of the most devastating adverse drug reactions. This review focuses on the current understanding of the surveillance, pathogenesis, and treatment of SJS/TEN, including the role of genomics and pharmacogenomics in the etiology, treatment, and eradication of preventable causes of drug-induced SJS/TEN. Gaps, unmet needs, and priorities for future research have been identified for the optimal management of drug-induced SJS/TEN in various ethnic populations. Pharmacogenomics holds great promise for optimal patient stratification and theranostics, yet its clinical implementation needs to be cost-effective and sustainable.

Canadian Network for Mood and Anxiety Treatments (CANMAT) and International Society for Bipolar Disorders (ISBD) 2018 guidelines for the management of patients with bipolar disorder

The Canadian Network for Mood and Anxiety Treatments (CANMAT) previously published treatment guidelines for bipolar disorder in 2005, along with international commentaries and subsequent updates in 2007, 2009, and 2013. The last two updates were published in collaboration with the International Society for Bipolar Disorders (ISBD). These 2018 CANMAT and ISBD Bipolar Treatment Guidelines represent the significant advances in the field since the last full edition was published in 2005, including updates to diagnosis and management as well as new research into pharmacological and psychological treatments. These advances have been translated into clear and easy to use recommendations for first, second, and third- line treatments, with consideration given to levels of evidence for efficacy, clinical support based on experience, and consensus ratings of safety, tolerability, and treatment-emergent switch risk. New to these guidelines, hierarchical rankings were created for first and second- line treatments recommended for acute mania, acute depression, and maintenance treatment in bipolar I disorder. Created by considering the impact of each treatment across all phases of illness, this hierarchy will further assist clinicians in making evidence-based treatment decisions. Lithium, quetiapine, divalproex, asenapine, aripiprazole, paliperidone, risperidone, and cariprazine alone or in combination are recommended as first-line treatments for acute mania. First-line options for bipolar I depression include quetiapine, lurasidone plus lithium or divalproex, lithium, lamotrigine, lurasidone, or adjunctive lamotrigine. While medications that have been shown to be effective for the acute phase should generally be continued for the maintenance phase in bipolar I disorder, there are some exceptions (such as with antidepressants); and available data suggest that lithium, quetiapine, divalproex, lamotrigine, asenapine, and aripiprazole monotherapy or combination treatments should be considered first-line for those initiating or switching treatment during the maintenance phase. In addition to addressing issues in bipolar I disorder, these guidelines also provide an overview of, and recommendations for, clinical management of bipolar II disorder, as well as advice on specific populations, such as women at various stages of the reproductive cycle, children and adolescents, and older adults. There are also discussions on the impact of specific psychiatric and medical comorbidities such as substance use, anxiety, and metabolic disorders. Finally, an overview of issues related to safety and monitoring is provided. The CANMAT and ISBD groups hope that these guidelines become a valuable tool for practitioners across the globe.

Frank Stinchfield Award: Identification of the At-risk Genotype for Development of Pseudotumors Around Metal-on-metal THAs

BACKGROUND

Once touted as the future of hip arthroplasty, metal-on-metal (MoM) bearing surfaces have fallen sharply from favor with the emergence of a strong body of evidence demonstrating unacceptably high premature implant failure rates. The previously unpredictable development of adverse local tissue reactions (ALTRs) has been a substantive contributor to this. Although the underlying pathophysiology of these so-called "pseudotumors" is now well understood, the fundamental predisposing patient risk factors have remained elusive.

QUESTIONS/PURPOSES

The aim of this research, as a clinical-genotype correlation analysis, was to identify specific alleles (genes) associated with the development of ALTRs in patients with in situ MoM THAs.

METHODS

A case-control study of patients who received a large-head, primary MoM THA between 2005 and 2008 was performed with a minimum followup of 5 years. Twenty-six patients who had undergone revision of a primary MoM THA secondary to symptomatic ALTRs were recruited. The mean timeframe from primary MoM THA to symptomatic revision was 5.5 years (range, 1-10 years). Twenty-eight control subjects were randomly selected asymptomatic patients with no evidence of ALTRs on protocol-specific screening. Baseline demographics and high-resolution genotype (human leukocyte antigen [HLA] Class II) were collected for all patients. Cohorts were similar with respect to age at the time of primary MoM THA (mean, 54.8 versus 54.9 years, p = 0.95) and serum cobalt (mean, 5.5 versus 8.5 μg/L, p = 0.09) and chromium concentrations (mean, 2.9 versus 4.2 μg/L, p = 0.27). The association between genotype and revision surgery secondary to ALTRs was determined with gender as a covariate.

RESULTS

The prevalence of the risk genotype was 30% (16 of 54) among the entire cohort. Adjusting for sex, the odds of revision were 6.1 times greater among patients with the risk genotype present than among patients without (95% confidence interval [CI], 1.5-25.4; p = 0.01). Among females, the specificity of the risk genotype was 1.0 (95% CIexact, 0.5-1.0; pexact = 0.03), and for males, it was 0.8 (95% CIexact, 0.6-0.9; pexact < 0.01).

CONCLUSIONS

The findings of this study suggest that, among patients with a primary MoM THA, allelic variation within the HLA Class II loci may be a strong, independent risk factor associated with the need for subsequent revision surgery secondary to pseudotumor formation.

CLINICAL RELEVANCE

Given the hypothesis-generating nature of this novel undertaking, confirmatory prospective clinical studies are required to further elucidate this correlation and to explore the clinical utility of targeted genetic screening in this specific population. This research may, however, represent a key missing piece in the puzzle that is metal ion-induced pseudotumor formation.

Lessons Learned From Past Gene-Environment Interaction Successes

Genetic and environmental factors are both known to contribute to susceptibility to complex diseases. Therefore, the study of gene-environment interaction (G×E) has been a focus of research for several years. In this article, select examples of G×E from the literature are described to highlight different approaches and underlying principles related to the success of these studies. These examples can be broadly categorized as studies of single metabolism genes, genes in complex metabolism pathways, ranges of exposure levels, functional approaches and model systems, and pharmacogenomics. Some studies illustrated the success of studying exposure metabolism for which candidate genes can be identified. Moreover, some G×E successes depended on the availability of high-quality exposure assessment and longitudinal measures, study populations with a wide range of exposure levels, and the inclusion of ethnically and geographically diverse populations. In several examples, large population sizes were required to detect G×Es. Other examples illustrated the impact of accurately defining scale of the interactions (i.e., additive or multiplicative). Last, model systems and functional approaches provided insights into G×E in several examples. Future studies may benefit from these lessons learned.

Stevens-Johnson Syndrome following Failure of Genetic Screening prior to Carbamazepine Prescription

Failure to screen susceptible individuals for human leucocyte allele B∗1502 leads to the onset of Stevens-Johnson syndrome (SJS). We report a case of a 27-year-old Malay female who was treated with carbamazepine following the diagnosis of trigeminal neuralgia without a genetic screening. She was prescribed 150 mg of carbamazepine initially and the dose was increased to 300 mg following the initial dose. A sudden development of skin and mucous membrane ulcers was observed and this warranted immediate hospitalization. A diagnosis of SJS was made and she was treated immediately with intravenous corticosteroids. Genetic screening prior to carbamazepine prescription is essential especially in susceptible populations.

Clinical and regulatory considerations in pharmacogenetic testing

PURPOSE

Both regulatory science and clinical practice rely on best available scientific data to guide decision-making. However, changes in clinical practice may be driven by numerous other factors such as cost. In this review, we reexamine noteworthy examples where pharmacogenetic testing information was added to drug labeling to explore how the available evidence, potential public health impact, and predictive utility of each pharmacogenetic biomarker impacts clinical uptake.

SUMMARY

Advances in the field of pharmacogenetics have led to new discoveries about the genetic basis for variability in drug response. The Food and Drug Administration recognizes the value of pharmacogenetic testing strategies and has been proactive about incorporating pharmacogenetic information into the labeling of both new drugs and drugs already on the market. Although some examples have readily translated to routine clinical practice, clinical uptake of genetic testing for many drugs has been limited.

CONCLUSION

Both regulatory science and clinical practice rely on data-driven approaches to guide decision making; however, additional factors are also important in clinical practice that do not impact regulatory decision making, and these considerations may result in heterogeneity in clinical uptake of pharmacogenetic testing.

Facile and phase-defined determination of HLA alleles with morpholino-functionalized nanoparticle probes

A number of human leukocyte antigen (HLA) gene alleles have been found to be genetic risk markers for immunologically mediated drug hypersensitivity. Clinical adoption of HLA pharmacogenomics requires facile and accurate allele screening assays. As HLA genes are highly polymorphic, currently available methods are usually labor-intensive and liable to generate false positives. Herein we report a general strategy for screening HLA alleles with nanoparticle probes. Specific HLA alleles can be identified by gauging three to five sequence variants. Single-polymerase chain reaction (PCR) and dual-PCR methods have been proposed to achieve phase-defined determination of the sequence variants. Morpholino-functionalized gold nanoparticle probes allow for colorimetric and highly specific detection. Assays for HLA-B*58:01 and HLA-B*15:02 have been developed and validated with 49 selected human genomic DNA samples. The facile nanoparticle probe-based assays can be implemented easily in molecular diagnostic laboratories for accurate and cost-effective screening of HLA alleles.

Pharmaceutical Management of Trigeminal Neuralgia in the Elderly

Classical trigeminal neuralgia (CTN) is a severe neuropathic pain in the distribution of one or more branches of the trigeminal nerve, which occurs in recurrent episodes, causing deterioration in quality of life, affecting everyday habits and inducing severe disability. The aim of this review is to give an overview of the current literature on pharmaceutical treatment options for CTN in the elderly. The first-line treatment for the management of CTN in adults is an antiepileptic—carbamazepine or oxcarbazepine. There is a lack of research on the use of antiepileptics in the elderly. This is a deficiency, as the use of antiepileptics raises a number of problems due to the polypharmacotherapy common in older patients. This can induce drug interactions due to co-morbidities and changes in pharmacokinetics and pharmacodynamics. Furthermore, the side effects of carbamazepine include central nervous system disturbances, such as a lack of balance, dizziness, somnolence, renal dysfunction and cardiac arrhythmias, which are poorly tolerated by the elderly. Unfortunately, the efficacy and safety of alternative treatment options have not been systematically evaluated. On the basis of the current literature, it is not possible to give an evidence-based recommendation for first-line pharmaceutical management of CTN specifically for the elderly.

Diagnosis and management of bipolar disorder in primary care: a DSM-5 update

This review discusses the diagnosis and detection of bipolar disorder in the primary care population with recent changes introduced by Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition and the pharmacotherapy and psychosocial management of this psychiatric condition.

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.

Real-world efficiency of pharmacogenetic screening for carbamazepine-induced severe cutaneous adverse reactions

Objectives

We evaluated the cost and efficiency of routine HLA-B*15∶02 screening to prevent carbamazepine-induced Stevens-Johnson syndrome and toxic epidermal necrolysis (CBZ-SJS/TEN) in Hong Kong.

Methods

Data were extracted from patients who commenced CBZ as the first-ever AED treatment or tested for HLA-B*15∶02 allele in three years before policy implementation (pre-policy: 16 September 2005 to 15 September 2008) and three years after (post-policy: 16 September 2008 to 15 September 2011). Using published unit costs, we estimated the cost of screening by comparing the costs to prevent and treat CBZ-SJS/TEN. We compared the number of person-tests needed and the cost to prevent resultant death with cancer screening programs.

Results

The number of screening tests needed to prevent one case of CBZ-SJS/TEN was 442, and to prevent one resultant death was 1,474 to 8,840. The screening cost was $332 per person, of which 42% was attributed to an additional consultation to review result and prescribe appropriate medication. HLA-B*15∶02 screening expended $146,749 to prevent a case of CBZ-SJS/TEN, and $489,386– $2,934,986 to prevent a resultant death. The corresponding numbers of tests and costs for mammography and Pap smear to prevent death due to breast and cervical cancers were 7,150 and 7,000, and $614,900 and $273,000, respectively. Comparing to the SJS/TEN treatment cost, HLA-B*15∶02 screening would become cost saving if a point-of-care test of less than $37 was available.

Conclusions

HLA-B*15∶02 screening is as efficient as mammography and Pap smear in preventing death. Development of point-of-care testing will vastly improve efficiency.

The search for circulating epilepsy biomarkers

Few would experience greater benefit from the development of biomarkers than those who suffer from epilepsy. Both the timing of individual seizures and the overall course of the disease are highly unpredictable, and the associated morbidity is considerable. Thus, there is an urgent need to develop biomarkers that can predict the progression of epilepsy and treatment response. Doing so may also shed light on the mechanisms of epileptogenesis and pharmacoresistance, which remain elusive despite decades of study. However, recent advances suggest the possible identification of circulating epilepsy biomarkers – accessible in blood, cerebrospinal fluid or urine. In this review, we focus on advances in several areas: neuroimmunology and inflammation; neurological viral infection; exemplary pediatric syndromes; and the genetics of pharmacoresistance, as relevant to epilepsy. These are fertile areas of study with great potential to yield accessible epilepsy biomarkers.

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

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

HLA and pharmacogenetics of drug hypersensitivity

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

The success of pharmacogenomics in moving genetic association studies from bench to bedside: study design and implementation of precision medicine in the post-GWAS era

Pharmacogenomics is emerging as a popular type of study for human genetics in recent years. This is primarily due to the many success stories and high potential for translation to clinical practice. In this review, the strengths and limitations of pharmacogenomics are discussed as well as the primary epidemiologic, clinical trial, and in vitro study designs implemented. A brief discussion of molecular and analytic approaches will be reviewed. Finally, several examples of bench-to-bedside clinical implementations of pharmacogenetic traits will be described. Pharmacogenomics continues to grow in popularity because of the important genetic associations identified that drive the possibility of precision medicine.

Biomarkers for antiepileptic drug response

The identification and validation of genetic factors ('biomarkers') that reliably predict the efficacy and toxicity of specific pharmacological agents for individual patients would significantly improve the current treatment of patients with epilepsy. A pharmacogenetic biomarker classification has been proposed that identifies three biomarker types involved in drug response: 'known valid biomarkers', 'probable valid biomarkers' and 'exploratory or research biomarkers'. The only known valid antiepileptic drug biomarker is HLA-B*1502 (Stevens-Johnson syndrome in patients of specific Asian backgrounds taking carbamazepine). Probable valid antiepileptic drug biomarkers include polymorphisms in one drug transporter gene, two drug metabolizing genes, three sodium channel genes and one HLA allele. Current methodological challenges to identifying new antiepileptic medication biomarkers can only be overcome with large-scale collaborative research efforts.