Recommendations for HLA-B*15:02 and HLA-A*31:01 genetic testing to reduce the risk of carbamazepine-induced hypersensitivity reactions

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Severe cutaneous adverse reactions

Severe cutaneous adverse reactions (SCARs), which include Stevens-Johnson syndrome and toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms (also known as drug-induced hypersensitivity syndrome), acute generalized exanthematous pustulosis, and generalized bullous fixed drug eruption, are life-threatening conditions. The pathogenesis of SCARs involves T cell receptors recognizing drug antigens presented by human leukocyte antigens, triggering the activation of distinct T cell subsets. These cells interact with keratinocytes and various immune cells, orchestrating cutaneous lesions and systemic manifestations. Genetic predisposition, impaired drug metabolism, viral reactivation or infections, and heterologous immunity influence SCAR development and clinical presentation. Specific genetic associations with distinct SCAR phenotypes have been identified, leading to the implementation of genetic screening before prescription in various countries to prevent SCARs. Whilst systemic corticosteroids and conventional immunomodulators have been the primary therapeutic agents, evolving strategies, including biologics and small molecules targeting tumour necrosis factor, different cytokines, or Janus kinase signalling pathways, signify a shift towards a precision management paradigm that considers individual clinical presentations.

Relationships between acute generalized eruptive pustulosis, age, sex, primary disease, and prescription medications: Further analysis of the Japanese Adverse Drug Event Report database

Background

Acute generalized eruptive pustulosis (AGEP) is a rare, but serious, drug-related adverse event. This study aimed to determine the relationships between AGEP and age, sex, primary disease, and prescription medications using a database of adverse drug events, namely, the Japanese Adverse Drug Event Report (JADER) database.

Methods

In this retrospective observational study, we analyzed AGEP reports extracted from the JADER database based on the preferred term for AGEP (code 10048799). We evaluated the effects of causative drugs, underlying diseases, age, and sex. The association between AGEP and prescription drugs was analyzed using the reporting odds ratio and adjusted for covariates using multiple logistic regression. Association rule mining was performed to evaluate the correlation between each combination of factors and AGEP.

Results

Between April 2004 and March 2023, 823,662 reports, including 869 reports on AGEP, were entered in the JADER database. The highest percentage of reports in each age group was in males aged <10 years, and clarithromycin was the most used drug in males aged <10 years. Nasopharyngitis was the most common reason for use, and Kawasaki disease was reported as a reason for use among males under 10 years of age, but not among females.

Conclusions

In boys aged <10 years, attention should be paid to the occurrence of AGEP when prescribing clarithromycin and treating Kawasaki disease.

Dutch Pharmacogenetics Working Group (DPWG) guideline for the gene-drug interaction of CYP2C9, HLA-A and HLA-B with anti-epileptic drugs

By developing evidence-based pharmacogenetics guidelines to optimize pharmacotherapy, the Dutch Pharmacogenetics Working Group (DPWG) aims to advance the implementation of pharmacogenetics (PGx). This guideline outlines the gene-drug interaction of CYP2C9 and HLA-B with phenytoin, HLA-A and HLA-B with carbamazepine and HLA-B with oxcarbazepine and lamotrigine. A systematic review was performed and pharmacotherapeutic recommendations were developed. For CYP2C9 intermediate and poor metabolisers, the DPWG recommends lowering the daily dose of phenytoin and adjust based on effect and serum concentration after 7-10 days. For HLA-B*15:02 carriers, the risk of severe cutaneous adverse events associated with phenytoin, carbamazepine, oxcarbazepine, and lamotrigine is strongly increased. For carbamazepine, this risk is also increased in HLA-B*15:11 and HLA-A*31:01 carriers. For HLA-B*15:02, HLA-B*15:11 and HLA-A*31:01 positive patients, the DPWG recommends choosing an alternative anti-epileptic drug. If not possible, it is recommended to advise the patient to report any rash while using carbamazepine, lamotrigine, oxcarbazepine or phenytoin immediately. Carbamazepine should not be used in an HLA-B*15:02 positive patient. DPWG considers CYP2C9 genotyping before the start of phenytoin "essential" for toxicity prevention. For patients with an ancestry in which the abovementioned HLA-alleles are prevalent, the DPWG considers HLA-B*15:02 genotyping before the start of carbamazepine, phenytoin, oxcarbazepine, and lamotrigine "beneficial", as well as genotyping for HLA-B*15:11 and HLA-A*31:01 before initiating carbamazepine.

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

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

Pharmacogenetics to prevent hypersensitivity reactions to antiepileptic drugs: is testing performed when indicated?

Extensive scientific evidence consistently demonstrates the clinical validity and utility of HLA-B*15:02 pre-screening in averting severe cutaneous adverse reactions (SCARs), namely Stevens-Johnson syndrome and toxic epidermal necrolysis, associated with carbamazepine or oxcarbazepine usage. Current practice guidelines and drug labeling actively advocate for pharmacogenetic pre-screening before initiating these antiepileptic drugs (AED), with particular emphasis on patients of Asian descent. However, there is a potential need to strengthen compliance with these recommendations. This retrospective study aimed to describe the pharmacogenetic pre-screening, documentation, and SCARs incidence for patients of Asian ancestry initiated on carbamazepine or oxcarbazepine at a large Northeastern USA healthcare system. Between 1 July 2016 and August 1, 2021, 27 patients with documented Asian heritage in the electronic health record (EHR) were included. The overall rate of HLA-B*15:02 pre-screening before carbamazepine or oxcarbazepine initiation was 4%. None who underwent pharmacogenetic pre-screening carried the associated HLA-B risk allele, and no SCARs were reported. Notably, pharmacogenetic results were not discretely entered into the EHR, and the results were only found as attached documents in the miscellaneous section of the EHR. There remains a significant opportunity for improving HLA-B*15:02 pre-screening for patients starting carbamazepine and oxcarbazepine to prevent SCARs in the USA.

Systematic Critical Review of Genetic Factors Associated with Cisplatin-induced Ototoxicity: Canadian Pharmacogenomics Network for Drug Safety 2022 Update

BACKGROUND

Cisplatin is commonly used to treat solid tumors; however, its use can be complicated by drug-induced hearing loss (ie, ototoxicity). The presence of certain genetic variants has been associated with the development/occurrence of cisplatin-induced ototoxicity, suggesting that genetic factors may be able to predict patients who are more likely to develop ototoxicity. The authors aimed to review genetic associations with cisplatin-induced ototoxicity and discuss their clinical relevance.

METHODS

An updated systematic review was conducted on behalf of the Canadian Pharmacogenomics Network for Drug Safety, based on the Preferred Reporting Items for Systematic reviews and Meta-Analyses 2020 statement. Pharmacogenomic studies that reported associations between genetic variation and cisplatin-induced ototoxicity were included. The evidence on genetic associations was summarized and evaluated, and knowledge gaps that can be used to inform future pharmacogenomic studies identified.

RESULTS

Overall, 40 evaluated reports, considering 47 independent patient populations, captured associations involving 24 genes. Considering GRADE criteria, genetic variants in 2 genes were strongly (ie, odds ratios ≥3) and consistently (ie, replication in ≥3 independent populations) predictive of cisplatin-induced ototoxicity. Specifically, an ACYP2 variant has been associated with ototoxicity in both children and adults, whereas TPMT variants are relevant in children. Encouraging evidence for associations involving several other genes also exists; however, further research is necessary to determine potential clinical relevance.

CONCLUSIONS

Genetic variation in ACYP2 and TPMT may be helpful in predicting patients at the highest risk of developing cisplatin-induced ototoxicity. Further research (including replication studies considering diverse pediatric and adult patient populations) is required to determine whether genetic variation in additional genes may help further identify patients most at risk.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Assessment of Need for Improved Identification of a Culprit Drug in Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis

Importance

Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) is a severe hypersensitivity reaction. Identifying a culprit drug is critical for patient care, yet identification is based on clinical judgment. Data are limited on the accuracy in or approach to identifying a culprit drug.

Objective

To evaluate patient allergy list outcomes, current approaches in identifying culprit drugs, and potential methods of improving culprit drug identification.

Design, Setting, and Participants

This retrospective cohort study spanned 18 years (January 2000 to July 2018), was conducted at Brigham and Women's Hospital and Massachusetts General Hospital (Boston), and included patients with clinically and histologically confirmed cases of SJS/TEN overlap and TEN.

Main Outcomes and Measures

This study descriptively analyzed potential culprits to SJS/TEN, patients' allergy lists, and currently used approaches that led to those lists. It then tested the theoretical contribution of incorporating various parameters to allergy list outcomes.

Results

Of 48 patients (29 women [60.4%]; 4 Asian [8.3%], 6 Black [12.5%], 5 Hispanic [10.4%], and 25 White [52.1%] individuals; median age, 40 years [range, 1-82 years]), the mean (SD) number of drugs taken per patient at disease onset was 6.5 (4.7). Physicians labeled 17 patients as allergic to a single culprit drug. Comparatively, 104 drugs were added to allergy lists across all patients. Physicians' approaches relied largely on heuristic identification of high-notoriety drugs and the timing of drug exposure. Use of a vetted database for drug risk improved sensitivity. Algorithm for Drug Causality for Epidermal Necrolysis scoring was discordant in 28 cases, labeling an additional 9 drugs missed by physicians and clearing 43 drugs labeled as allergens by physicians. Human leukocyte antigen testing could have potentially affected 20 cases. Consideration of infection as a culprit was limited.

Conclusions and Relevance

The results of this cohort study suggest that currently used approaches to identify culprit drugs in SJS/TEN are associated with overlabeling patients allergic to likely nonculprit drugs and less commonly missed possible culprit drugs. Incorporation of a systematized unbiased approach could potentially improve culprit drug identification, although ultimately a diagnostic test is necessary.

PAnno: A pharmacogenomics annotation tool for clinical genomic testing

Introduction: Next-generation sequencing (NGS) technologies have been widely used in clinical genomic testing for drug response phenotypes. However, the inherent limitations of short reads make accurate inference of diplotypes still challenging, which may reduce the effectiveness of genotype-guided drug therapy. Methods: An automated Pharmacogenomics Annotation tool (PAnno) was implemented, which reports prescribing recommendations and phenotypes by parsing the germline variant call format (VCF) file from NGS and the population to which the individual belongs. Results: A ranking model dedicated to inferring diplotypes, developed based on the allele (haplotype) definition and population allele frequency, was introduced in PAnno. The predictive performance was validated in comparison with four similar tools using the consensus diplotype data of the Genetic Testing Reference Materials Coordination Program (GeT-RM) as ground truth. An annotation method was proposed to summarize prescribing recommendations and classify drugs into avoid use, use with caution, and routine use, following the recommendations of the Clinical Pharmacogenetics Implementation Consortium (CPIC), etc. It further predicts phenotypes of specific drugs in terms of toxicity, dosage, efficacy, and metabolism by integrating the high-confidence clinical annotations in the Pharmacogenomics Knowledgebase (PharmGKB). PAnno is available at https://github.com/PreMedKB/PAnno. Discussion: PAnno provides an end-to-end clinical pharmacogenomics decision support solution by resolving, annotating, and reporting germline variants.

Implementation of pharmacogenomics: Where are we now?

Pharmacogenomics (PGx), examining the effect of genetic variation on interpatient variation in drug disposition and response, has been widely studied for several decades. However, as cost, as well as turnaround time associated with PGx testing, has significantly improved, the use of PGx in the clinical setting has been gaining momentum. Nevertheless, challenges have emerged in the broader clinical implementation of PGx. In this review, we will outline current models of PGx delivery and methodologies of evaluation, and discuss clinically relevant PGx tests and associated medications. Additionally, we will describe our approach for the broad implementation of pre-emptive DPYD genotyping in patients taking fluoropyrimidines in Ontario, Canada, as an example of clinically actionable PGx testing with sufficient clinical evidence of patient benefit that can become a new standard of patient care. We will highlight challenges associated with PGx testing, including a lack of diversity in PGx studies as well as general limitations that impact the broad adoption of PGx testing. Lastly, we examine the future of PGx, discussing new clinical targets, methodologies and analysis approaches.

HLA pharmacogenetic markers of drug hypersensitivity from the perspective of the populations of the Greater Middle East

Specific HLA associations with drug hypersensitivity may vary between geographic regions and ethnic groups. There are little to no data related to HLA-drug hypersensitivity on populations who reside in the Greater Middle East (GME), a vast region spanning from Morocco in the west to Pakistan in the east. In this review, the authors intended to summarize the significant HLA alleles associated with hypersensitive drug reactions induced by different drugs, as have been found in different populations, and to summarize the prevalence of these alleles in the specific and diverse populations of the GME. For example, HLA-B*57:01 allele prevalence, associated with abacavir-induced hypersensitivity, ranges from 1% to 3%, and HLA-DPB1*03:01 prevalence, associated with aspirin-induced asthma, ranges from 10% to 14% in the GME population. Studying pharmacogenomic associations in the ethnic groups of the GME may allow the discovery of new associations, confirm ones found with a low evidence rate and enable cost-effectiveness analysis of allele screening before drug use.

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

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

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

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

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

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 Reaction with Eosinophilia and Systemic Symptoms (DReSS)/Drug-Induced Hypersensitivity Syndrome (DiHS)—Readdressing the DReSS

Drug reaction with eosinophilia and systemic symptoms (DReSS), also known as drug-induced hypersensitivity syndrome (DiHS), is a severe, systemic, T cell mediated drug reaction with combinations of cutaneous, hematologic, and internal organ involvement. Pathogenesis of DReSS is multi-factorial, involving drug-exposure, genetic predisposition through specific human leukocyte antigen (HLA) alleles and metabolism defects, viral reactivation, and immune dysregulation. Clinical features of this condition are delayed, stepwise, and heterogenous, making this syndrome challenging to recognize and diagnose. Two sets of validated diagnostic criteria exist that can be employed to diagnose DReSS/DiHS. Methods to improve early recognition of DReSS and predict disease severity has been a recent area of research focus. In vitro and in vivo tests can be employed to confirm the diagnosis and help identify culprit drugs. The mainstay treatment of DReSS is prompt withdrawal of the culprit drug, supportive treatment, and immunosuppression depending on the severity of disease. We present a comprehensive review on the most recent research and literature on DReSS, with emphasis on pathogenesis, clinical features, diagnosis, confirmatory testing modalities, and treatment. Additionally, this summary aims to highlight the differing viewpoints on this severe disease and broaden our perspective on the condition known as DReSS.

Evolution of HLA-B Pharmacogenomics and the Importance of PGx Data Integration in Health Care System: A 10 Years Retrospective Study in Thailand

Background: The HLA-B is the most polymorphic gene, play a crucial role in drug-induced hypersensitivity reactions. There is a lot of evidence associating several risk alleles to life-threatening adverse drug reactions, and a few of them have been approved as valid biomarkers for predicting life-threatening hypersensitivity reactions.

Objectives: The objective of this present study is to present the progression of HLA-B pharmacogenomics (PGx) testing in the Thai population during a 10‐year period, from 2011 to 2020.

Methods: This was a retrospective observational cohort study conducted at the Faculty of Medicine Ramathibodi Hospital. Overall, 13,985 eligible patients who were tested for HLA-B risk alleles between periods of 2011–2020 at the study site were included in this study.

Results: The HLA PGx testing has been increasing year by year tremendously, 94 HLA-B testing was done in 2011; this has been raised to 2,880 in 2020. Carbamazepine (n = 4,069, 33%), allopurinol (n = 4,675, 38%), and abacavir (n = 3,246, 26%) were the most common drugs for which the HLA-B genotyping was performed. HLA-B*13:01, HLA-B*15:02 and HLA-B*58:01 are highly frequent, HLA-B*51:01 and HLA-B*57:01 are moderately frequent alleles that are being associated with drug induced hypersensitivity. HLA-B*59:01 and HLA-B*38:01 theses alleles are rare but has been reported with drug induced toxicity. Most of the samples were from state hospital (50%), 36% from private clinical laboratories and 14% from private hospitals.

Conclusion: According to this study, HLA-B PGx testing is increasing substantially in Thailand year after year. The advancement of research in this field, increased physician awareness of PGx, and government and insurance scheme reimbursement assistance could all be factors. Incorporating PGx data, along with other clinical and non-clinical data, into clinical decision support systems (CDS) and national formularies, on the other hand, would assist prescribers in prioritizing therapy for their patients. This will also aid in the prediction and prevention of serious adverse drug reactions.

Single Nucleotide Variants as Proxies for HLA-A*31:01 in Native American Populations

Carbamazepine triggers dermatologic hypersensitivity reactions, associated with specific human leukocyte antigens (HLAs), especially HLA-B*15:02 and HLA-A*31:01. Previous efforts to identify single nucleotide variants (SNVs) with high predictive value as HLA proxies, revealed that rs1061235 and rs17179220 fulfill these requirements for HLA-A*31:01 in some but not all populations. Herein we explored the predictive performance of rs1061235 and rs17179220 as HLA-A*31:01 tags in populations of Native American ancestry, which are largely underrepresented in pharmacogenomic studies. The study cohorts comprised the overall Admixed American superpopulation of the 1000 Genomes Project (1 KG_AMR), a subcohort of individuals with predominant Native American ancestry (1 KG_NAT), the Native American population of the Human Genome Diversity Project (HGDP), plus Kaingang (KRC) and Guarani (GRC and GKW) adults from indigenous reservation areas in Brazil. The diversity of cohorts is reflected in the range of frequencies of HLA-A*31:01 (0.02–0.65), rs1061235 (0.03–0.13) and rs17179220 (0.12–0.66), as well as in the predictive performance of these SNVs as HLA-A*31:01 proxies. NPV (negative predictive value), the metric of primary interest for pharmacogenetic-informed carbamazepine prescription was maximal (NPV = 1.0) for both SNVs in 1 KG_AMR and 1 KG_NAT, for rs17179220, but not rs1061235 (NPV = 0.91) in HGDP, and for rs17179220 in GWK, but not GRC (NPV = 0.88) or KRC (NPV = 0.80). Collectively, the data support the notion that rs1061235 and rs17179220 are not optimal proxies for HLA-A*31:01 across populations of Native American ancestry.

Factors not considered in the study of drug-resistant epilepsy: Drug-resistant epilepsy: assessment of neuroinflammation

More than one‐third of people with epilepsy develop drug‐resistant epilepsy (DRE). Different hypotheses have been proposed to explain the origin of DRE. Accumulating evidence suggests the contribution of neuroinflammation, modifications in the integrity of the blood‐brain barrier (BBB), and altered immune responses in the pathophysiology of DRE. The inflammatory response is mainly due to the increase of cytokines and related molecules; these molecules have neuromodulatory effects that contribute to hyperexcitability in neural networks that cause seizure generation. Some patients with DRE display the presence of autoantibodies in the serum and mainly cerebrospinal fluid. These patients are refractory to the different treatments with standard antiseizure medications (ASMs), and they could be responding well to immunomodulatory therapies. This observation emphasizes that the etiopathogenesis of DRE is involved with immunology responses and associated long‐term events and chronic inflammation processes. Furthermore, multiple studies have shown that functional polymorphisms as risk factors are involved in inflammation processes. Several relevant polymorphisms could be considered risk factors involved in inflammation‐related DRE such as receptor for advanced glycation end products (RAGE) and interleukin 1β (IL‐1β). All these evidences sustained the hypothesis that the chronic inflammation process is associated with the DRE. However, the effect of the chronic inflammation process should be investigated in further clinical studies to promote the development of novel therapeutics useful in treatment of DRE.

The use of pharmacogenetic testing in psychiatry

ABSTRACT

Psychiatric pharmacogenetic testing is commonly used by providers in primary care and mental health settings. The purpose of this article is to describe the extent to which psychiatric pharmacogenetic testing supports clinical practice. human leukocyte antigen (HLA)-A and HLA-B should be tested before initiating carbamazepine and oxcarbazepine due to risk of serious skin reactions. For psychotropic medications metabolized through the liver, limited evidence suggests testing for variation in metabolism through CYP2D6 and CYP2D19. For specific medication and genotype-phenotype variations, guidance through the Clinical Pharmacogenetics Implementation Consortium (CPIC) or the International Society of Psychiatric Genetics (ISPG) should be reviewed. Commercial tests interpret this information differently and should not be used for broad guidance. Clinicians should follow current guidelines from professional bodies such as CPIC or ISPG and test for HLA-A or HLA-B before initiating carbamazepine or oxcarbazepine. Evidence is limited for psychiatric pharmacogenetic testing. Clinicians should continue to follow best practice and clinical practice guidelines.

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

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

Genetic Variations Associated with Long-Term Treatment Response in Bipolar Depression

Several pharmacogenetic-based decision support tools for psychoactive medication selection are available. However, the scientific evidence of the gene-drug pairs analyzed is mainly based on pharmacogenetic studies in patients with major depression or schizophrenia, and their clinical utility is mostly assessed in major depression. This study aimed at evaluating the impact of individual genes, with pharmacogenetic relevance in other psychiatric conditions, in the response to treatment in bipolar depression. Seventy-six patients diagnosed with bipolar disorder and an index major depressive episode were included in an observational retrospective study. Sociodemographic and clinical data were collected, and all patients were genotyped using a commercial multigene pharmacogenomic-based tool (Neuropharmagen^®, AB-Biotics S.A., Barcelona, Spain). Multiple linear regression was used to identify pharmacogenetic and clinical predictors of efficacy and tolerability of medications. The pharmacogenetic variables response to serotonin-norepinephrine reuptake inhibitors (SNRIs) (ABCB1) and reduced metabolism of quetiapine (CYP3A4) predicted patient response to these medications, respectively. ABCB1 was also linked to the tolerability of SNRIs. An mTOR-related multigenic predictor was also associated with a lower number of adverse effects when including switch and autolytical ideation. Our results suggest that the predictors identified could be useful to guide the pharmacological treatment in bipolar disorder. Additional clinical studies are necessary to confirm these findings.

Validation of Single Nucleotide Variant Assays for Human Leukocyte Antigen Haplotypes HLA-B*15:02 and HLA-A*31:01 Across Diverse Ancestral Backgrounds

The human leukocyte antigen haplotypes HLA-B*15:02 and HLA-A*31:01 have been linked to life-threatening adverse drug reactions to the anticonvulsants carbamazepine and oxcarbazepine. Identification of these haplotypes via pharmacogenetic techniques facilitates implementation of precision medicine to prevent such reactions. Using reference samples from diverse ancestral origins, we investigated the test analytical validity (i.e., ability to detect whether or not the haplotypes were present or absent) of TaqMan assays for single nucleotide variants previously identified as potentially being able to "tag" these haplotypes. A TaqMan custom assay for rs10484555 and an inventoried assay for rs17179220 and were able to identify with 100% sensitivity and 100% specificity HLA-B*15:02 and HLA-A*31:01 respectively. A custom assay for rs144012689 that takes into account a neighboring single nucleotide variant with manual calling was also able to identify HLA-B*15:02 with 100% sensitivity and 100% specificity. A custom assay for rs106235 identified HLA-A*31:01 with 100% sensitivity and 95% specificity. The slight reduction in specificity for the latter was owing to another haplotype (HLA-A*33:03) also being detected. While any positive call using the rs106235 assay could therefore be further investigated, as the presence of the HLA-A*31:01 haplotype confers adverse drug reaction risk, the absence of false negatives (indexed by sensitivity) is more important than false positives. In summary, we present validated TaqMan assay methodology for efficient detection of HLA haplotypes HLA-B*15:02 and HLA-A*31:01. Our data are relevant for other genotyping technologies that identify, or have the potential to identify, these haplotypes using single nucleotide variants.

Genotyping HLA alleles to predict the development of Severe cutaneous adverse drug reactions (SCARs): state-of-the-art

Introduction: Pharmacogenomics has great potential in reducing drug-induced severe cutaneous adverse drug reactions (SCARs). Pharmacogenomic studies have revealed an association between HLA genes and SCARs including acute generalized exanthematous pustulosis (AGEP), drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN).Areas covered: Pharmacogenomics-guided therapy could prevent severe drug hypersensitivity reactions. The US Food and Drug Administration (FDA), Clinical Pharmacogenetics Implementation Consortium (CPIC), and Dutch Pharmacogenetics Working Group (DPWG) provided guidelines in the translation of clinically relevant and evidence-based SCARs pharmacogenomics research into clinical practice. In this review, we intended to summarize the significant HLA alleles associated with SCARs induced by different drugs in different populations. We also summarize the SCARs associated with genetic and non-genetic factors and the cost-effectiveness of screening tests.Expert opinion: The effectiveness of HLA screening on a wider scale in clinical practice requires significant resources, including state-of-the-art laboratory; multidisciplinary team approach and health care provider education and engagement; clinical decision support alert system via electronic medical record (EMR); laboratory standards and quality assurance; evidence of cost-effectiveness; and cost of pharmacogenomics tests and reimbursement.

Efficacy of Carbamazepine and Its Derivatives in the Treatment of Bipolar Disorder

Background and Objectives: This review is dedicated to the use of carbamazepine and its derivatives oxcarbazepine and eslicarbazepine in bipolar disorder and their relative strengths in treating and preventing new depressive or manic episodes. This paper will discuss the evidence of their efficacy relative to the polarity of relapse from controlled acute and maintenance/relapse prevention studies in bipolar patients. Materials and Methods: A Medline search was conducted for controlled acute and maintenance studies with carbamazepine, oxcarbazepine, and eslicarbazepine in bipolar disorder. In addition, abstracts reporting on controlled studies with these medications from key conferences were taken into consideration. Results: Information was extracted from 84 articles on the acute and prophylactic efficacy of the medications under consideration. They all appear to have stronger efficacy in treating acute mania than depression, which also translates to better protection against manic than depressive relapses for carbamazepine. Still, there is a paucity of controlled acute studies on bipolar depression for all and, with the exception of carbamazepine, a lack of long-term monotherapy maintenance data. For eslicarbazepine, the efficacy in bipolar disorder remains largely unknown. Especially with carbamazepine, tolerability issues and drug-drug interactions need to be kept in mind. Conclusions: Two of the medications discussed in this review, carbamazepine and oxcarbazepine, match Class A criteria according to the criteria proposed by Ketter and Calabrese, meaning acute antimanic efficacy, prevention of manic relapses, and not causing or worsening depression.

Severe cutaneous adverse reaction associated with antiseizure medications: Diagnosis, management, and prevention

Severe cutaneous adverse reactions (SCARs) are potentially life-threatening, with considerable morbidity and mortality. They are nonimmediate hypersensitivity reactions that occur in specifically predisposed patients with delayed T-cell-mediated hypersensitivity reaction. Antiseizure medications (ASMs) are among the drugs that can induce SCAR. Increased awareness of SCAR among clinicians treating patients with ASMs is critically important for early recognition of symptoms, prompt identification and removal of the causal drug, and early intervention to reduce SCAR-related acute and long-term morbidity and mortality. The diagnosis, management, and prevention of Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS) are reviewed, along with the current understanding of the pathomechanisms and role of genetics in SCAR development. Supportive care and immunomodulating treatments for SCAR are discussed.

Pharmacogenomics in Pain Management: A Review of Relevant Gene-Drug Associations and Clinical Considerations

OBJECTIVE

To provide an overview of clinical recommendations regarding genomic medicine relating to pain management and opioid use disorder.

DATA SOURCES

A literature review was conducted using the search terms pain management, pharmacogenomics, pharmacogenetics, pharmacokinetics, pharmacodynamics, and opioids on PubMed (inception to February 1, 2021), CINAHL (2016 through February 1, 2021), and EMBASE (inception through February 1, 2021).

STUDY SELECTION AND DATA EXTRACTION

All relevant clinical trials, review articles, package inserts, and guidelines evaluating applicable pharmacogenotypes were considered for inclusion.

DATA SYNTHESIS

More than 300 Food and Drug Administration-approved medications contain pharmacogenomic information in their labeling. Genetic variability may alter the therapeutic effects of commonly prescribed pain medications. Pharmacogenomic-guided therapy continues to gain traction in clinical practice, but a multitude of barriers to widespread pharmacogenomic implementation exist.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Pain is notoriously difficult to treat given the need to balance safety and efficacy when selecting pharmacotherapy. Pharmacogenomic data can help optimize outcomes for patients with pain. With improved technological advances, more affordable testing, and a better understanding of genomic variants resulting in treatment disparities, pharmacogenomics continues to gain popularity. Unfortunately, despite these and other advancements, pharmacogenomic testing and implementation remain underutilized and misunderstood in clinical care, in part because of a lack of health care professionals trained in assessing and implementing test results.

CONCLUSIONS

A one-size-fits-all approach to pain management is inadequate and outdated. With increasing genomic data and pharmacogenomic understanding, patient-specific genomic testing offers a comprehensive and personalized treatment alternative worthy of additional research and consideration.

PharmaKU: A Web-Based Tool Aimed at Improving Outreach and Clinical Utility of Pharmacogenomics

With the tremendous advancements in genome sequencing technology in the field of pharmacogenomics, data have to be made accessible to be more efficiently utilized by broader clinical disciplines. Physicians who require the drug–genome interactome information, have been challenged by the complicated pharmacogenomic star-based classification system. We present here an end-to-end web-based pharmacogenomics tool, PharmaKU, which has a comprehensive easy-to-use interface. PharmaKU can help to overcome several hurdles posed by previous pharmacogenomics tools, including input in hg38 format only, while hg19/GRCh37 is now the most popular reference genome assembly among clinicians and geneticists, as well as the lack of clinical recommendations and other pertinent dosage-related information. This tool extracts genetic variants from nine well-annotated pharmacogenes (for which diplotype to phenotype information is available) from whole genome variant files and uses Stargazer software to assign diplotypes and apply prescribing recommendations from pharmacogenomic resources. The tool is wrapped with a user-friendly web interface, which allows for choosing hg19 or hg38 as the reference genome version and reports results as a comprehensive PDF document. PharmaKU is anticipated to enable bench to bedside implementation of pharmacogenomics knowledge by bringing precision medicine closer to a clinical reality.

Access to precision medicine in Thailand: a comparative study

Purpose

This study explored health insurance coverage of genetic testing and potential factors associated with precision medicine (PM) reimbursement in Thailand.

Design/methodology/approach

The study employed a targeted review method. Thirteen PMs were selected to represent four PM categories: targeted cancer therapy candidate, prediction of adverse drug reactions (ADRs), dose adjustment and cancer risk prediction. Content analysis was performed to compare access to PMs among three health insurance schemes in Thailand. The primary outcome of the study was evaluating PM test reimbursement status. Secondary outcomes included clinical practice guidelines, PMs statement in FDA-approved leaflet and economic evaluation.

Findings

Civil Servant Medical Benefits Scheme (CSMBS) provided more generous access to PM than Universal Coverage Scheme (UCS) and Social Security Scheme (SSS). Evidence of economic evaluations likely impacted the reimbursement decisions of SSS and UCS, while the information provided in FDA-approved leaflets seemed to impact the reimbursement decisions of CSMBS. Three health insurance schemes provided adequate access to PM tests for some cancer-targeted therapies, while gaps existed for access to PM tests for serious ADRs prevention, dose adjustment and cancer risk prediction.

Originality/value

This was the first study to explore the situation of access to PMs in Thailand. The evidence alerts public health insurance schemes to reconsider access to PMs. Development of health technology assessment guidelines for PM test reimbursement decisions should be prioritized.

Whole-Exome Sequencing in Patients Affected by Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis Reveals New Variants Potentially Contributing to the Phenotype

Background

Adverse drug reactions (ADRs) are frequent occurring events that can essentially be defined as harmful or unpleasant symptoms secondary to the use of a medicinal product. ADRs involve a wide spectrum of clinical manifestations ranging from minor itching and rash to life-threatening reactions. Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare ADRs. SJS-TEN may be considered a polygenic pathology due to additive/epistatic effects caused by sequence variants in numerous genes. Next-generation sequencing (NGS) represents a potentially interesting exploration tool in such scenario as it facilitates the simultaneous analysis of large genomic regions and genes at affordable cost.

Methods

The present study has involved using whole-exome sequencing (WES) for the first time on SJS-TEN patients. It involved robust and innovative multistep bioinformatics analysis focusing on 313 candidate genes potentially participating in the disease’s aetiology, specific drugs’ metabolism and gene regulation.

Results

We identified combinations of frequently occurring and rare variants that may contribute to the disease’s pathogenesis. Depending on the specific drug being taken, different variants (and alleles) in NAT2, CYP2D8, CYP2B6, ABCC2, UGT2B7 and TCF3 were identified as coherent candidates representing potential future markers for SJS-TEN.

Conclusion

The present study proposed and has described (for the first time) a large-scale genomic analysis of patients affected by SJS-TEN. The genes and variants identified represent relevant candidates potentially participating in the disease’s pathogenesis. Corroborating that proposed by others, we found that complex combinations of frequently occurring and rare variants participating in particular drug metabolism molecular cascades could be associated with the phenotype. TCF3 TF may be considered a coherent candidate for SJS-TEN that should be analysed in new cohorts of patients having ADRs.

Synthesis of major pharmacogenomics pretest counseling themes: a multisite comparison

The accessibility of pharmacogenomic (PGx) testing has grown substantially over the last decade and with it has arisen a demand for patients to be counseled on the use of these tests. While guidelines exist for the use of PGx results; objective determinants for who should receive PGx testing remain incomplete. PGx clinical services have been created to meet these screening and education needs and significant variability exists between these programs. This article describes the practices of four PGx clinics during pretest counseling sessions. A description of the major tenets of the benefits, limitations and risks of testing are compiled. Additional tools are provided to serve as a foundation for those wishing to begin or expand their own counseling service.

Pharmacogenetics Guidelines: Overview and Comparison of the DPWG, CPIC, CPNDS, and RNPGx Guidelines

Many studies have shown that the efficacy and risk of side effects of drug treatment is influenced by genetic variants. Evidence based guidelines are essential for implementing pharmacogenetic knowledge in daily clinical practice to optimize pharmacotherapy of individual patients. A literature search was performed to select committees developing guidelines with recommendations being published in English. The Dutch Pharmacogenetics Working Group (DPWG), the Clinical Pharmacogenetics Implementation Consortium (CPIC), the Canadian Pharmacogenomics Network for Drug Safety (CPNDS), and the French National Network (Réseau) of Pharmacogenetics (RNPGx) were selected. Their guidelines were compared with regard to the methodology of development, translation of genotypes to predicted phenotypes, pharmacotherapeutic recommendations and recommendations on genotyping. A detailed overview of all recommendations for gene-drug combinations is given. The committees have similar methodologies of guideline development. However, the objectives differed at the start of their projects, which have led to unique profiles and strengths of their guidelines. DPWG and CPIC have a main focus on pharmacotherapeutic recommendations for a large number of drugs in combination with a patient’s genotype or predicted phenotype. DPWG, CPNDS and RNPGx also recommend on performing genetic testing in daily clinical practice, with RNPGx even describing specific clinical settings or medical conditions for which genotyping is recommended. Discordances exist, however committees also initiated harmonizing projects. The outcome of a consensus project was to rename “extensive metabolizer (EM)” to “normal metabolizer (NM)”. It was decided to translate a CYP2D6 genotype with one nonfunctional allele (activity score 1.0) into the predicted phenotype of intermediate metabolizer (IM). Differences in recommendations are the result of the methodologies used, such as assessment of dose adjustments of tricyclic antidepressants. In some cases, indication or dose specific recommendations are given for example for clopidogrel, codeine, irinotecan. The following drugs have recommendations on genetic testing with the highest level: abacavir (HLA), clopidogrel (CYP2C19), fluoropyrimidines (DPYD), thiopurines (TPMT), irinotecan (UGT1A1), codeine (CYP2D6), and cisplatin (TPMT). The guidelines cover many drugs and genes, genotypes, or predicted phenotypes. Because of this and their unique features, considering the totality of guidelines are of added value. In conclusion, many evidence based pharmacogenetics guidelines with clear recommendations are available for clinical decision making by healthcare professionals, patients and other stakeholders.

Retrospective Study of Patients With SJS/TEN Treated at a Tertiary Burn Unit in Canada: Overview of 17 Years of Treatment

BACKGROUND

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are adverse drug reactions.

OBJECTIVES

To learn about the clinical characteristics of patients with SJS/TEN including treatments provided, outcomes, and mortality.

METHODS

We conducted a retrospective chart review of patients who were hospitalized with the diagnosis of SJS/TEN at the Ross Tilley Burn Center between the years 1999 and 2015.

RESULTS

A total of 43 patients were identified with a mean age of 54 ± 19 (58, 18-85). The most common offending medications were allopurinol and carbamazepine. The overall mortality rate in our study is 21% with the most common causes of death being multiorgan failure and sepsis. The majority of our patients had oral (84%), ocular (79%), and genital (60%) involvement during hospitalization. Our data revealed that combination treatment involving oral corticosteroids with intravenous immunoglobulin (IVIG) had the highest mortality rate in our study since 55% (6/11) of patients who were treated in this manner passed away compared to 11% (2/18) of patients passing away who were treated with solely IVIG and 33% (1/3) who were treated with only supportive care. Our study also demonstrates the addition of etanercept and cyclosporine treatment in the second time period we studied: 2008-2015 versus the earlier time period of 1999-2007. None of the patients in our study who were treated with therapies including cyclosporine and/or etanercept passed away.

CONCLUSIONS

Our study sheds light on a possible beneficial role of cyclosporine and etanercept for the treatment of SJS and TEN and reinforces the necessity of a multidisciplinary care team for patients.

The hepatotoxicity of Polygonum multiflorum: The emerging role of the immune-mediated liver injury

Herbal and dietary supplements (HDS)-induced liver injury has been a great concern all over the world. Polygonum multiflorum Thunb., a well-known Chinese herbal medicine, is recently drawn increasing attention because of its hepatotoxicity. According to the clinical and experimental studies, P. multiflorum-induced liver injury (PM-DILI) is considered to be immune-mediated idiosyncratic liver injury, but the role of immune response and the underlying mechanisms are not completely elucidated. Previous studies focused on the direct toxicity of PM-DILI by using animal models with intrinsic drug-induced liver injury (DILI). However, most epidemiological and clinical evidence demonstrate that PM-DILI is immune-mediated idiosyncratic liver injury. The aim of this review is to assess current epidemiological, clinical and experimental evidence about the possible role of innate and adaptive immunity in the idiosyncratic hepatotoxicity of P. multiflorum. The potential effects of factors associated with immune tolerance, including immune checkpoint molecules and regulatory immune cells on the individual's susceptibility to PM-DILI are also discussed. We conclude by giving our hypothesis of possible immune mechanisms of PM-DILI and providing suggestions for future studies on valuable biomarkers identification and proper immune models establishment.

Frequencies of Genetic Polymorphisms of Clinically Relevant Gene-Drug Pairs in a German Psychiatric Inpatient Population

INTRODUCTION

Genetic variation is known to affect enzymatic activities allowing differentiating various metabolizer types (e. g., slow or rapid metabolizers), in particular CYP2C19 and CYP2D6.

METHODS

PGx-testing was conducted in adult major depressive disorder inpatients admitted to the Vitos Klinik Eichberg between 11/2016 and 7/2017 (n=108, 57% female). We conducted a two-sided Z-Test (p=0.05) to analyze and compare frequencies of CYP2D6, CYP2C19, CYP3A4, CYP3A5 and CYP2C9 metabolizer groups with other European and psychiatric inpatient cohorts. The HLA-A and -B genes were also analyzed.

RESULTS

Non-normal metabolizer status of CYP2D6 were present in 47%. More specifically, 35 % were intermediate, 7% poor and 4% ultra-rapid metabolizers. 68% were CYP2C19 non-normal metabolizers. 8% were ultra-rapid and 31% rapid metabolizers. Notably, only 13% were NM for CYP2C19 and NM for CYP2D6 (activity score of 1 or more). For CYP2C9 we found 16% to be intermediate metabolizers, 1.0% poor metabolizer. CYP3A4 and CYP3A5 genetic polymorphisms were present in 25% and 19% respectively. HLA-B TAG- SNPs for *15:01 was positive in 25 patients, showing the need for different Tag-SNPs in Caucasians. HLA-B *57:01 TAG-SNP was positive in 8% of the patients, HLA-A TAG-SNP for *31:01 in Caucasians was positive in 9%. Z-Test showed statistical significance for our results.

DISCUSSION

Our results suggest that our psychiatric inpatients were enriched with genotypes consistent with non-normal drug metabolism compared to reference populations. We therefore conclude that pharmacogenetic testing should be implemented in clinical practice to guide drug therapy.

Trigeminal Neuralgia: Basic and Clinical Aspects

The trigeminal nerve is the largest of all cranial nerves. It has three branches that provide the main sensory innervation of the anterior two-thirds of the head and face. Trigeminal neuralgia (TN) is characterized by sudden, severe, brief, and stabbing recurrent episodes of facial pain in one or more branches of the trigeminal nerve. Pain attacks can occur spontaneously or can be triggered by non-noxious stimuli, such as talking, eating, washing the face, brushing teeth, shaving, a light touch or even a cool breeze. In addition to pain attacks, a proportion of the patients also experience persistent background pain, which along with autonomic signs and prolonged disease duration, represent predictors of worse treatment outcomes. It is now widely accepted that the presence of a neurovascular compression at the trigeminal root entry zone is an anatomic abnormality with a high correlation with classical TN. However, TN may be related to other etiologies, thus presenting different and/or additional features. Since the 1960s, the anticonvulsant carbamazepine is the drug of choice for TN treatment. Although anti-epileptic drugs are commonly used to treat neuropathic pain in general, the efficacy of carbamazepine has been largely limited to TN. Carbamazepine, however, is associated with dose-limiting side-effects, particularly with prolonged usage. Thus, a better understanding and new treatment options are urgently warranted for this rare, but excruciating disease.

Challenges and Opportunities in Implementing Pharmacogenetic Testing in Clinical Settings

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

Human Leukocyte Antigen Gene Testing and Carbamazepine-Induced Toxic Epidermal Necrolysis: A Study of Pediatric Practice

BACKGROUND

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening drug-induced dermatologic conditions. SJS/TEN occurs in 1-10 per 10 000 patients taking carbamazepine (CBZ) (Pratt VM, McLeod HL, Rubinstein WS et al. Medical Genetics Summaries. National Center for Biotechnology Information US; 2018: 1-527). The development of SJS/TEN is associated with variable drug metabolism and presence of an at-risk HLA haplotype. HLA-B*15:02 and HLA-A*31:01 haplotypes can produce a hyperimmune response in the setting of CBZ use in patients of Asian and European descent, respectively (Schneider JA, Cohen PR. Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis: A concise review with a comprehensive summary of therapeutic interventions emphasizing supportive measures. Adv Ther. 2017; 34:1235-1244).

OBJECTIVE

The US Food and Drug Administration (FDA) and the Canadian pharmacogenomics Network for Drug Safety (CPNDS) recommend that patients with high-risk ethnic backgrounds should be genetic tested before initiating CBZ (Sukasem C, Chaichan C, Nakkrut T et al. Association between HLA-B Alleles and Carbamazepine-induced maculopapular exanthema and severe cutaneous reactions in Thai patients. Journal of Immunology Research. 2018; 1-11).We sought out to assess the awareness of this in prescribing practitioners and their standard of practice.

METHODS

We created a 15-question survey and distributed to pediatric neurologists and pediatricians at the University of Alberta. We hypothesized that there was a discordance between the standard of practice and the recommendation by the FDA and CPNDS.

RESULTS

The survey results indicated a lack of awareness of the at-risk ethnicities for CBZ-induced SJS/TEN. HLA gene testing was rarely done prior to initiation of CBZ in high-risk patients. In addition, there was a lack of awareness for standard of care for genetic testing in Canada and worldwide.

CONCLUSIONS

Our results demonstrate an evident gap between current prescriber practices and existing FDA and CPNDS recommendations to screen for HLA genotypes. We hope that this study captures the realistic potential to improve patient outcomes.

Pediatric drug eruptions

Drug eruptions in children are common but in general less studied than their adult counterparts. Aside from having significant impact on the child's health and quality of life, these reactions can limit what medications the patient can receive in the future. Familiarity with pediatric drug eruptions is important for accurate diagnosis and to prevent future recurrence or ineffective therapy. Our current understanding of how drug reactions differ mechanistically between children and adults is poor. There are multiple factors that could be contributing to the differing incidence, presentation, and treatment modalities offered to pediatric versus adult patients. For many of these cutaneous drug reactions, the treatment regime is not standardized, being based primarily on case reports. Although not comprehensive, this review highlights common pediatric drug eruption patterns and discuss diagnostic mimickers. Five cutaneous adverse drug reactions in the pediatric population are presented: morbilliform (exanthematous) eruptions, urticarial eruptions, serum sickness-like reactions, fixed drug eruptions, and DRESS syndrome. Clinical features, diagnostic workup, and management are discussed with an emphasis on the pediatric population.

Recent advances in managing and understanding Stevens-Johnson syndrome and toxic epidermal necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening diseases characterized by detachment of the epidermis and mucous membrane. SJS/TEN are considered to be on the same spectrum of diseases with different severities. They are classified by the percentage of skin detachment area. SJS/TEN can also cause several complications in the liver, kidneys, and respiratory tract. The pathogenesis of SJS/TEN is still unclear. Although it is difficult to diagnose early stage SJS/TEN, biomarkers for diagnosis or severity prediction have not been well established. Furthermore, optimal therapeutic options for SJS/TEN are still controversial.

Several drugs, such as carbamazepine and allopurinol, are reported to have a strong relationship with a specific human leukocyte antigen (HLA) type. This relationship differs between different ethnicities. Recently, the usefulness of HLA screening before administering specific drugs to decrease the incidence of SJS/TEN has been investigated.

Skin detachment in SJS/TEN skin lesions is caused by extensive epidermal cell death, which has been considered to be apoptosis via the Fas-FasL pathway or perforin/granzyme pathway. We reported that necroptosis, i.e. programmed necrosis, also contributes to epidermal cell death. Annexin A1, released from monocytes, and its interaction with the formyl peptide receptor 1 induce necroptosis. Several diagnostic or prognostic biomarkers for SJS/TEN have been reported, such as CCL-27, IL-15, galectin-7, and RIP3.

Supportive care is recommended for the treatment of SJS/TEN. However, optimal therapeutic options such as systemic corticosteroids, intravenous immunoglobulin, cyclosporine, and TNF-α antagonists are still controversial. Recently, the beneficial effects of cyclosporine and TNF-α antagonists have been explored. In this review, we discuss recent advances in the pathophysiology and management of SJS/TEN.

Epidemiology and Risk Factors for Severe Delayed Drug Hypersensitivity Reactions

Severe delayed drug hypersensitivity reactions comprise different clinical entities and can involve different immune-mediated mechanisms. Common examples are severe cutaneous adverse reactions and druginduced internal organ injuries. The incidence of such reactions is overall low but seems to be on the rise reaching numbers as high as 9 per million individuals-years in the case of SJS/TEN and DRESS. Such conditions carry an important associated morbidity, and mortality can attain 40% in SJS/TEN patients, making these hypersensitivity reactions important targets when implementing preventive measures. Several risk factors have been identified for reaction severity; some are transverse, such as older age and underlying chronic diseases. The recent advances in pharmacogenetics allowed the identification of specific populations with higher risk and permitted strategic avoidance of certain drugs being HLA-B*57:01 screening in patients initiating abacavir the best successful example. In this work, we reviewed the epidemiology of SCARs and liver/kidney/lung drug-induced immune-mediated reactions. We focus on particular aspects such as prevalence and incidence, drugs involved, mortality and risk factors.

Current challenges and possible future developments in personalized psychiatry with an emphasis on psychotic disorders

A personalized medicine approach seems to be particularly applicable to psychiatry. Indeed, considering mental illness as deregulation, unique to each patient, of molecular pathways, governing the development and functioning of the brain, seems to be the most justified way to understand and treat disorders of this medical category. In order to extract correct information about the implicated molecular pathways, data can be drawn from sampling phenotypic and genetic biomarkers and then analyzed by a machine learning algorithm. This review describes current difficulties in the field of personalized psychiatry and gives several examples of possibly actionable biomarkers of psychotic and other psychiatric disorders, including several examples of genetic studies relevant to personalized psychiatry. Most of these biomarkers are not yet ready to be introduced in clinical practice. In a next step, a perspective on the path personalized psychiatry may take in the future is given, paying particular attention to machine learning algorithms that can be used with the goal of handling multidimensional datasets.

Integration analysis of metabolites and single nucleotide polymorphisms improves the prediction of drug response of celecoxib

INTRODUCTION

Pharmacogenetics and pharmacometabolomics are the common methods for personalized medicine, either genetic or metabolic biomarkers have limited predictive power for drug response.

OBJECTIVES

In order to better predict drug response, the study attempted to integrate genetic and metabolic biomarkers for drug pharmacokinetics prediction.

METHODS

The study chose celecoxib as study object, the pharmacokinetic behavior of celecoxib was assessed in 48 healthy volunteers based on UPLC-MS/MS platform, and celecoxib related single nucleotide polymorphisms (SNPs) were also detected. Three mathematic models were constructed for celecoxib pharmacokinetics prediction, the first one was mainly based on celecoxib-related SNPs; the second was based on the metabolites selected from a pharmacometabolomic analysis by using GC-MS/MS method, the last model was based on the combination of the celecoxib-related SNPs and metabolites above.

RESULTS

The result proved that the last model showed an improved prediction power, the integration model could explain 71.0% AUC variation and predict 62.3% AUC variation. To facilitate clinical application, ten potential celecoxib-related biomarkers were further screened, which could explain 68.3% and predict 54.6% AUC variation, the predicted AUC was well correlated with the measured values (r = 0.838).

CONCLUSION

This study provides a new route for personalized medicine, the integration of genetic and metabolic biomarkers can predict drug response with a higher accuracy.

Association of HLA genotypes with phenytoin induced severe cutaneous adverse drug reactions in Thai children

PURPOSE

Phenytoin (PHT) is a common causative drug for severe cutaneous adverse drug reactions (SCARs) in children. SCARs, including drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), are associated with a variation in HLA genotypes. Blood screening for specific HLA allele before PHT prescription would help in the reduction of the incidence of PHT induced SCARs. This study was to investigate the association between variations of HLA genotypes and PHT induced SCARs in Thai children.

METHODS

Cases were Thai children aged between 0-18 years diagnosed with SCARs from PHT. Control groups were Thai children of corresponding age who had taken PHT for a least 12 weeks without any hypersensitivity reaction and healthy population controls. Blood samples from both groups were collected for HLA genotyping using a reverse-sequence specific oligonucleotide (SSO) probes method. Carrier rates of HLA alleles were compared between 22 cases (17 DRESS and 5 SJS-TEN), 60 tolerant controls and 649 population controls.

RESULTS

Two HLA alleles includingHLA-B*51:01 and HLA-C*14:02 were significantly associated with PHT induced DRESS (OR 5.83; 95 % CI 1.36-25.00, p = 0.022 and OR 5.85; 95 % CI 1.16-29.35, p = 0.039). HLA-B*38:02 was significantly associated with PHT induced SJS-TEN (OR12.67; 95 % CI 1.50-106.89, p = 0.044). Haplotype analysis demonstrated the association of HLA haplotype A*11:01-B*51:01-C*14:02 and PHT induced DRESS compared to tolerant controls and the healthy population control group (OR 8.92; 95 % CI 1.47-54.02, p = 0.019, and OR 10.2; 95 % CI 3.04-34.21, p = 0.002). HLA haplotype B*38:02-C*07:01 in PHT induced SJS-TEN was significantly higher than those in tolerant controls and the healthy population control group (40 % vs 3.3 % vs 0.3 %; OR 19.33; 95 % CI 1.98-188.59, p = 0.027 and OR 215.67; 95 % CI 22.40-2076.04, p = 0.0003. HLA-B*15:02 was not associated with PHT induced SCARs.

SIGNIFICANCE

An association betweenHLA-B*51:01 and HLA-C*14:02 and PHT induced DRESS and HLA-B*38:02 and PHT induced SJS-TEN has been demonstrated in Thai children.

SJS/TEN 2019: From science to translation

Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are potentially life-threatening, immune-mediated adverse reactions characterized by widespread erythema, epidermal necrosis, and detachment of skin and mucosa. Efforts to grow and develop functional international collaborations and a multidisciplinary interactive network focusing on SJS/TEN as an uncommon but high burden disease will be necessary to improve efforts in prevention, early diagnosis and improved acute and long-term management. SJS/TEN 2019: From Science to Translation was a 1.5-day scientific program held April 26-27, 2019, in Vancouver, Canada. The meeting successfully engaged clinicians, researchers, and patients and conducted many productive discussions on research and patient care needs.

The genetics of bipolar disorder

Bipolar disorder (BD) is one of the most heritable mental illnesses, but the elucidation of its genetic basis has proven to be a very challenging endeavor. Genome-Wide Association Studies (GWAS) have transformed our understanding of BD, providing the first reproducible evidence of specific genetic markers and a highly polygenic architecture that overlaps with that of schizophrenia, major depression, and other disorders. Individual GWAS markers appear to confer little risk, but common variants together account for about 25% of the heritability of BD. A few higher-risk associations have also been identified, such as a rare copy number variant on chromosome 16p11.2. Large scale next-generation sequencing studies are actively searching for other alleles that confer substantial risk. As our understanding of the genetics of BD improves, there is growing optimism that some clear biological pathways will emerge, providing a basis for future studies aimed at molecular diagnosis and novel therapeutics.