The association of ABCB1 gene polymorphism with clinical response to carbamazepine monotherapy in patients with epilepsy

BACKGROUND

Epilepsy is a common neurological disease but around 30% of patients fail to respond to antiepileptic drug (AED) treatment. Genetic variation of the ATP-binding cassette subfamily B, member 1 (ABCB1) gene, a drug efflux transporter may infer treatment resistance by decreasing gastrointestinal absorption and preventing AED entry into the brain. This study examined the impact of ABCB1 genetic variants on carbamazepine responsiveness.

MATERIALS AND METHODS

Genomic DNA was extracted from whole blood of 104 epileptic patients. Genotyping of 3 ABCB1 variants (c.C3435T, c.G2677T/A and c.C1236T) was undertaken using validated TaqMan allelic discrimination assays. Plasma carbamazepine levels were measured at 3 and 6 months following the initial dose using high-performance liquid chromatography (HPLC) alongside clinical outcomes evaluation.

RESULTS

Nonresponse to carbamazepine (CBZ) was associated significantly with the ABCB1 variants c.C3435T, c.G2677T/A, c.C1236T and TTT, TTC haplotypes (P < 0.05). There was no significant association between variants and plasma CBZ level (P > 0.05).

CONCLUSIONS

Our results showed that variant alleles of the ABCB1 gene and TTT, TTC haplotypes were significantly associated with CBZ resistance without affecting the plasma level of carbamazepine. The findings of this study may help to predict patient's response to treatment ultimately it will improve the personalized and evidence based treatment choice of patients with epilepsy.

TNF-α induced extracellular release of keratinocyte high-mobility group box 1 in Stevens-Johnson syndrome/toxic epidermal necrolysis: Biomarker and putative mechanism of pathogenesis

Decreased epidermal high-mobility group box 1 (HMGB1) expression is an early marker of epidermal injury in Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). Etanercept, an anti-tumor necrosis factor therapeutic, is effective in the treatment of SJS/TEN. The objective was to characterize antitumor necrosis factor-alpha (TNF-α)-mediated HMGB1 keratinocyte/epidermal release and etanercept modulation. HMGB1 release from TNF-α treated (± etanercept), or doxycycline-inducible RIPK3 or Bak-expressing human keratinocyte cells (HaCaTs) was determined by western blot/ELISA. Healthy skin explants were treated with TNF-α or serum (1:10 dilution) from immune checkpoint inhibitor-tolerant, lichenoid dermatitis or SJS/TEN patients ± etanercept. Histological and immunohistochemical analysis of HMGB1 was undertaken. TNF-α induced HMGB1 release in vitro via both necroptosis and apoptosis. Exposure of skin explants to TNF-α or SJS/TEN serum resulted in significant epidermal toxicity/detachment with substantial HMGB1 release which was attenuated by etanercept. Whole-slide image analysis of biopsies demonstrated significantly lower epidermal HMGB1 in pre-blistered SJS/TEN versus control (P < 0.05). Keratinocyte HMGB1 release, predominantly caused by necroptosis, can be attenuated by etanercept. Although TNF-α is a key mediator of epidermal HMGB1 release, other cytokines/cytotoxic proteins also contribute. Skin explant models represent a potential model of SJS/TEN that could be utilized for further mechanistic studies and targeted therapy screening.

Corrigendum: CYP3A genetic variation and taxane-induced peripheral neuropathy: a systematic review, meta-analysis, and candidate gene study

[This corrects the article DOI: 10.3389/fphar.2023.1178421.].

CYP3A genetic variation and taxane-induced peripheral neuropathy: a systematic review, meta-analysis, and candidate gene study

Background: Taxane-induced peripheral neuropathy (TIPN) is an important cause of premature treatment cessation and dose-limitation in cancer therapy. It also reduces quality of life and survivorship in affected patients. Genetic polymorphisms in the CYP3A family have been investigated but the findings have been inconsistent and contradictory. Methods: A systematic review identified 12 pharmacogenetic studies investigating genetic variation in CYP3A4*22 and CYP3A5*3 and TIPN. In our candidate gene study, 288 eligible participants (211 taxane participants receiving docetaxel or paclitaxel, and 77 control participants receiving oxaliplatin) were successfully genotyped for CYP3A4*22 and CYP3A5*3. Genotyping data was transformed into a combined CYP3A metaboliser phenotype: Poor metabolisers, intermediate metabolisers and extensive metabolisers. Individual genotypes and combined CYP3A metaboliser phenotypes were assessed in relation to neurotoxicity, including by meta-analysis where possible. Results: In the systematic review, no significant association was found between CYP3A5*3 and TIPN in seven studies, with one study reporting a protective association. For CYP3A4*22, one study has reported an association with TIPN, while four other studies failed to show an association. Evaluation of our patient cohort showed that paclitaxel was found to be more neurotoxic than docetaxel (p < 0.001). Diabetes was also significantly associated with the development of TIPN. The candidate gene analysis showed no significant association between either SNP (CYP3A5*3 and CYP3A4*22) and the development of TIPN overall, or severe TIPN. Meta-analysis showed no association between these two variants and TIPN. Transformed into combined CYP3A metaboliser phenotypes, 30 taxane recipients were poor metabolisers, 159 were intermediate metabolisers, and 22 were extensive metabolisers. No significant association was observed between metaboliser status and case-control status. Summary: We have shown that the risk of peripheral neuropathy during taxane chemotherapy is greater in patients who have diabetes. CYP3A genotype or phenotype was not identified as a risk factor in either the candidate gene analysis or the systematic review/meta-analysis, although we cannot exclude the possibility of a minor contribution, which would require a larger sample size.

Transcobalamin receptor gene polymorphisms and mutation in an elderly population

BACKGROUND & AIMS

Cellular uptake of the essential nutrient vitamin B12 (cobalamin) occurs via the transcobalamin receptor (TCblR/CD320), a ubiquitous membrane receptor. Polymorphisms in the receptor exist, though the effect of such variants across patient populations is unknown.

METHODS

We determined CD320 genotype in 377 randomly selected elderly individuals.

RESULTS

Three polymorphisms and a codon deletion were identified in the exon 2 region. Haplotype variants had significantly higher holotranscobalamin (holo-TC) values and a higher holo-TC/total cobalamin ratio. TCblR haplotype explained 46% of the variability in holo-TC values.

CONCLUSIONS

This has significant implications for the clinical utility of the 'combined indicator' of B12 status since it is based on a standard rate of intracellular flux via the TC-Cbl receptor. Modification of the model may be required to account for CD320 haplotype.

Platelet-derived growth factor D expression in adrenal cells is modulated by corticosteroids: putative role in adrenal suppression

BACKGROUND

Adrenal suppression is a clinically concerning side effect of inhaled corticosteroid (ICS) treatment in patients with asthma. Increased susceptibility to ICS-induced adrenal suppression has previously been identified in those with the rs591118 polymorphism in platelet-derived growth factor D (PDGFD). The mechanism underpinning this relationship is not known.

METHODS

H295R cells were genotyped for rs591118 using a validated Taqman PCR allelic discrimination assay. H295R cell viability was determined after treatment with beclometasone and fluticasone (range 0-330 μM). Cortisol was measured in cell culture medium using competitive enzyme immunoassay.

RESULTS

PDGFD protein expression in H295R cells was confirmed using Western blotting. When ACTH and forskolin were added to H295R cells, a reduction in PDGFD expression was seen, which was then restored by incubation with prochloraz, a known inhibitor of steroidogenesis. A dose-dependent, decrease in PDGFD expression was observed with beclometasone (over a 24 h incubation period) but not with beclometasone incubations beyond 24 h nor with fluticasone (at 24 or 48 h).

CONCLUSIONS

H295R cells express PDGFD protein, which can be modulated by incubation with steroidogenesis agonists and antagonists and additionally with exogenous beclometasone.

IMPACT

PDGFD is expressed in the human adrenal cell line, H295R, and expression can be modulated by beclometasone as well as agonists/antagonists of steroidogenesis. This builds on previous research that identified a SNP in PDGFD (rs591118) as an independent risk factor for adrenal suppression in adults and children with obstructive airway disease treated with inhaled corticosteroids. First in vitro experiments to support a link between the PDGF and cortisol production pathways, supporting the hypothesis that PDGFD variants can affect an individual's sensitivity to corticosteroid-induced adrenal suppression.

TNF-α‒Mediated Keratinocyte Expression and Release of Matrix Metalloproteinase 9: Putative Mechanism of Pathogenesis in Stevens‒Johnson Syndrome/Toxic Epidermal Necrolysis

Stevens‒Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are severe cutaneous adverse drug reactions characterized by widespread keratinocyte cell death and epidermal detachment. At present, there is little understanding of how the detachment occurs or how it is abrogated by the TNF-α inhibitor etanercept, an effective SJS/TEN treatment. RNA sequencing was used to identify upregulated transcripts in formalin-fixed paraffin-embedded SJS/TEN skin biopsies. Epidermal matrix metalloproteinase 9 (MMP9) expression was assessed by immunohistochemistry in skin biopsies and cultured human skin explants exposed to serum from patients with cutaneous adverse drug reactions. TNF-α‒induced MMP9 expression and activity and its abrogation by etanercept were determined using the HaCaT immortalized keratinocyte cell line. Epidermal MMP9 expression was significantly higher in SJS/TEN skin (70.6%) than in healthy control skin (0%) (P = 0.0098) and nonbullous skin reactions (10.7%) (P = 0.0002). SJS/TEN serum induced significant MMP9 expression and collagenase activity in healthy skin explants, which was reduced by etanercept. Etanercept was also able to negate the TNF-α‒induced MMP9 expression in the HaCaT cell line. Data suggest that elevated epidermal MMP9 expression and collagenase activity are a putative pathogenic mechanism in SJS/TEN, which is limited by etanercept. Modulation of MMP9 expression and activity represents, to our knowledge, a previously unreported therapeutic target for the treatment of SJS/TEN.

Genome-Wide association between EYA1 and Aspirin-induced peptic ulceration

Background

Low-dose aspirin can cause gastric and duodenal ulceration, hereafter called peptic ulcer disease (PUD). Predisposition is thought to be related to clinical and genetic factors; our aim was to identify genetic risk factors associated with aspirin-induced PUD.

Methods

Patients (n=1478) were recruited from 15 UK hospitals. Cases (n=505) were defined as patients with endoscopically confirmed PUD within 2 weeks of using aspirin and non-aspirin Non-Steroidal Anti-Inflammatory Drugs (NSAIDs). They were compared to two control groups: patients with endoscopically confirmed PUD without any history of NSAID use within 3 months of diagnosis (n=495), and patients with no PUD on endoscopy (n=478). A genome-wide association study (GWAS) of aspirin-induced cases (n=247) was compared to 476 controls. The results were validated by replication in another 84 cases and 162 controls.

Findings

The GWAS identified one variant, rs12678747 (p=1·65×10⁻⁷) located in the last intron of EYA1 on chromosome 8. The association was replicated in another sample of 84 PUD patients receiving aspirin (p=0·002). Meta-analysis of discovery and replication cohort data for rs12678747, yielded a genome-wide significant association (p=3·12×10⁻¹¹; OR=2·03; 95% CI 1·65-2·50). Expression of EYA1 was lower at the gastric ulcer edge when compared with the antrum.

Interpretation

Genetic variation in an intron of the EYA1 gene increases the risk of endoscopically confirmed aspirin-induced PUD. Reduced EYA1 expression in the upper gastrointestinal epithelium may modulate risk, but the functional basis of this association will need mechanistic evaluation.

Funding

Department of Health Chair in Pharmacogenetics, MRC Centre for Drug Safety Science and the Barts Cardiovascular NIHR Biomedical Research Centre, British Heart Foundation (BHF)

Pharmacogenomics of NSAID-Induced Upper Gastrointestinal Toxicity

Non-steroidal anti-inflammatory drugs (NSAIDs) are a group of drugs which are widely used globally for the treatment of pain and inflammation, and in the case of aspirin, for secondary prevention of cardiovascular disease. Chronic non-steroidal anti-inflammatory drug use is associated with potentially serious upper gastrointestinal adverse drug reactions (ADRs) including peptic ulcer disease and gastrointestinal bleeding. A few clinical and genetic predisposing factors have been identified; however, genetic data are contradictory. Further research is needed to identify clinically relevant genetic and non-genetic markers predisposing to NSAID-induced peptic ulceration.

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

Aims

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

Methods

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

Results

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

Conclusion

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

Beta-lactam-induced immediate hypersensitivity reactions: A genome-wide association study of a deeply phenotyped cohort

BACKGROUND

β-lactam antibiotics are associated with a variety of immune-mediated or hypersensitivity reactions, including immediate (type I) reactions mediated by antigen-specific IgE.

OBJECTIVE

We sought to identify genetic predisposing factors for immediate reactions to β-lactam antibiotics.

METHODS

Patients with a clinical history of immediate hypersensitivity reactions to either penicillins or cephalosporins, which were immunologically confirmed, were recruited from allergy clinics. A genome-wide association study was conducted on 662 patients (the discovery cohort) with a diagnosis of immediate hypersensitivity and the main finding was replicated in a cohort of 98 Spanish cases, recruited using the same diagnostic criteria as the discovery cohort.

RESULTS

Genome-wide association study identified rs71542416 within the Class II HLA region as the top hit (P = 2 × 10^-14); this was in linkage disequilibrium with HLA-DRB1∗10:01 (odds ratio, 2.93; P = 5.4 × 10^-7) and HLA-DQA1∗01:05 (odds ratio, 2.93, P = 5.4 × 10^-7). Haplotype analysis identified that HLA-DRB1∗10:01 was a risk factor even without the HLA-DQA1∗01:05 allele. The association with HLA-DRB1∗10:01 was replicated in another cohort, with the meta-analysis of the discovery and replication cohorts showing that HLA-DRB1∗10:01 increased the risk of immediate hypersensitivity at a genome-wide level (odds ratio, 2.96; P = 4.1 × 10^-9). No association with HLA-DRB1∗10:01 was identified in 268 patients with delayed hypersensitivity reactions to β-lactams.

CONCLUSIONS

HLA-DRB1∗10:01 predisposed to immediate hypersensitivity reactions to penicillins. Further work to identify other predisposing HLA and non-HLA loci is required.

Pharmacogenomics of anticancer drugs: Personalising the choice and dose to manage drug response

The field of pharmacogenomics has made great strides in oncology over the last 20 years and indeed a significant number of pre-emptive genetic tests are now routinely undertaken prior to anticancer drug administration. Many of these gene-drug interactions are the fruits of candidate gene and genome-wide association studies, which have largely focused on common genetic variants (allele frequency>1%). Examples where there is clinical utility include genotyping or phenotyping for G6PD to prevent rasburicase-induced RBC haemolysis, and TPMT to prevent thiopurine-induced bone marrow suppression. Other associations such as CYP2D6 status in determining the efficacy of tamoxifen are more controversial because of contradictory evidence from different sources, which has led to variability in the implementation of testing. As genomic technology becomes ever cheaper and more accessible, we must look to the additional data our genome can provide to explain interindividual variability in anticancer drug response. Clearly genes do not act on their own and it is therefore important to investigate genetic factors in conjunction with clinical factors, interacting concomitant drug therapies and other factors such as the microbiome, which can all affect drug disposition. Taking account of all of these factors, in conjunction with the somatic genome, is more likely to provide better predictive accuracy in determining anticancer drug response, both efficacy and safety. This review summarises the existing knowledge related to the pharmacogenomics of anticancer drugs and discusses areas of opportunity for further advances in personalisation of therapy in order to improve both drug safety and efficacy.

Informatics investigations into anti-thyroid drug induced agranulocytosis associated with multiple HLA-B alleles

INTRODUCTION

Adverse drug reactions have been linked with HLA alleles in different studies. These HLA proteins play an essential role in the adaptive immune response for the presentation of self and non-self peptides. Anti-thyroid drugs methimazole and propylthiouracil have been associated with drug induced agranulocytosis (severe lower white blood cell count) in patients with B*27:05, B*38:02 and DRB1*08:03 alleles in different populations: Taiwanese, Vietnamese, Han Chinese and Caucasian.

METHODS

In this study, informatics methods were used to investigate if any sequence or structural similarities exist between the two associated HLA-B alleles, compared with a set of "control" alleles assumed not be associated, which could help explain the molecular basis of the adverse drug reaction. We demonstrated using MHC Motif Viewer and MHCcluster that the two alleles do not have a propensity to bind similar peptides, and thus at a gross level the structure of the antigen presentation region of the two alleles are not similar. We also performed multiple sequence alignment to identify polymorphisms shared by the risk but not by the control alleles and molecular docking to compare the predicted binding poses of the drug-allele combinations.

RESULTS

Two residues, Cys67 and Thr80, were identified from the multiple sequence alignments to be unique to these risk alleles alone. The molecular docking showed the poses of the risk alleles to favour the F-pocket of the peptide binding groove, close to the Thr80 residue, with the control alleles generally favouring a different pocket. The data are thus suggestive that Thr80 may be a critical residue in HLA-mediated anti-thyroid drug induced agranulocytosis, and thus can guide future research and risk assessment.

Genetic influence of ABCG2, UGT1A1 and NR1I2 on dolutegravir plasma pharmacokinetics

Objectives

Dolutegravir has replaced efavirenz as first-line treatment in universal HIV guidelines. We sought to ascertain the contributory effect of SNPs in four key genes linked to dolutegravir disposition (UGT1A1, ABCG2, CYP3A and NR1I2) on plasma dolutegravir pharmacokinetics.

Methods

Paired pharmacogenetic/pharmacokinetic data from 93 subjects were analysed for association using multivariate linear regression.

Results

Co-occurring UGT1*28 and NR1I2 c.63396C&gt;T homozygosity was associated with a 79% increase in AUC0–24 (P = 0.001; 27% if analysed individually), whilst combined ABCG2 c.421C&gt;A and NR1I2 c.63396C&gt;T variants were associated with a 43% increase in Cmax (P = 0.002) and a 39% increase in AUC0–24 (P = 0.002). When analysed individually, homozygosity for the NR1I2 c.63396C&gt;T variant alleles was associated with a 28% increase in Cmax (P = 0.033) and homozygosity for the ABCG2 c.421C&gt;A variant alleles was associated with a 28% increase in Cmax (P = 0.047). The UGT1A1*28 (rs8175347) poor metabolizer status (*28/*28; *28/*37; *37/*37) was individually associated with a 27% increase in AUC0–24 (P = 0.020). The combination of UGT1A1*28 poor metabolizer and UGT1A1*6 intermediate metabolizer statuses correlated with a 43% increase in AUC0–24 (P = 0.023).

Conclusions

This study showed a pharmacogenetic association between dolutegravir pharmacokinetics and variants in the ABCG2, UGT1A1 and NR1I2 genes, particularly when combined. Further research is warranted to confirm these associations in population-specific studies and to investigate their putative relationship with dolutegravir pharmacodynamics.

Genomewide Association Study of Statin-Induced Myopathy in Patients Recruited Using the UK Clinical Practice Research Datalink

Statins can be associated with myopathy. We have undertaken a genomewide association study (GWAS) to discover and validate genetic risk factors for statin‐induced myopathy in a “real‐world” setting. One hundred thirty‐five patients with statin myopathy recruited via the UK Clinical Practice Research Datalink were genotyped using the Illumina OmniExpress Exome version 1.0 Bead Chip and compared with the Wellcome Trust Case‐Control Consortium (n = 2,501). Nominally statistically significant single nucleotide polymorphism (SNP) signals in the GWAS (P < 5 × 10⁻⁵) were further evaluated in several independent cohorts (comprising 332 cases and 449 drug‐tolerant controls). Only one (rs4149056/c.521C>T in the SLCO1B1 gene) SNP was genomewide significant in the severe myopathy (creatine kinase > 10 × upper limit of normal or rhabdomyolysis) group (P = 2.55 × 10⁻⁹; odds ratio 5.15; 95% confidence interval 3.13–8.45). The association with SLCO1B1 was present for several statins and replicated in the independent validation cohorts. The data highlight the role of SLCO1B1 c.521C>T SNP as a replicable genetic risk factor for statin myopathy. No other novel genetic risk factors with a similar effect size were identified.

Pharmacogenomics of statin-related myopathy: Meta-analysis of rare variants from whole-exome sequencing

AIMS

Statin-related myopathy (SRM), which includes rhabdomyolysis, is an uncommon but important adverse drug reaction because the number of people prescribed statins world-wide is large. Previous association studies of common genetic variants have had limited success in identifying a genetic basis for this adverse drug reaction. We conducted a multi-site whole-exome sequencing study to investigate whether rare coding variants confer an increased risk of SRM.

METHODS AND RESULTS

SRM 3-5 cases (N = 505) and statin treatment-tolerant controls (N = 2047) were recruited from multiple sites in North America and Europe. SRM 3-5 was defined as symptoms consistent with muscle injury and an elevated creatine phosphokinase level >4 times upper limit of normal without another likely cause of muscle injury. Whole-exome sequencing and variant calling was coordinated from two analysis centres, and results of single-variant and gene-based burden tests were meta-analysed. No genome-wide significant associations were identified. Given the large number of cases, we had 80% power to identify a variant with minor allele frequency of 0.01 that increases the risk of SRM 6-fold at genome-wide significance.

CONCLUSIONS

In this large whole-exome sequencing study of severe statin-related muscle injury conducted to date, we did not find evidence that rare coding variants are responsible for this adverse drug reaction. Larger sample sizes would be required to identify rare variants with small effects, but it is unclear whether such findings would be clinically actionable.

Serum and blister-fluid elevation and decreased epidermal content of high-mobility group box 1 protein in drug-induced Stevens-Johnson syndrome/toxic epidermal necrolysis

BACKGROUND

High-mobility group box 1 (HMGB1) is a damage-associated molecular-pattern protein. Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) are serious, immune-mediated skin-blistering conditions.

OBJECTIVES

To determine serum and/or blister-fluid total HMGB1 levels in SJS/TEN cohorts, and HMGB1 expression in formalin-fixed, paraffin-embedded (FFPE) SJS/TEN skin vs. healthy and maculopapular exanthema (MPE) skin. Methods Serum HMGB1 was quantified in Malawian nevirapine-induced hypersensitivity, Taiwanese SJS/TEN and Spanish SJS/TEN cohorts. FFPE skin (healthy skin, MPE, SJS/TEN) was stained and assessed for HMGB1 expression.

RESULTS

Serum total HMGB1 was not significantly elevated in patients with nevirapine-induced SJS/TEN (3·98 ± 2·17 ng mL^-1 ), MPE (3·92 ± 2·75 ng mL^-1 ) or drug reaction with eosinophilia and systemic symptoms (4·73 ± 3·00 ng mL^-1 ) vs. tolerant controls (2·97 ± 3·00 ng mL^-1 ). HMGB1 was significantly elevated in Taiwanese patients with SJS/TEN, highest during the acute phase (32·6 ± 26·6 ng mL^-1 ) vs. the maximal (19·7 ± 23·2 ng mL^-1 ; P = 0·007) and recovery (24·6 ± 25·3 ng mL^-1 ; P = 0·027) phases. In blister fluid from Spanish patients with SJS/TEN, HMGB1 (486·8 ± 687·9 ng mL^-1 ) was significantly higher than in serum (8·8 ± 7·6 ng mL^-1 ; P <0·001). Preblistered SJS/TEN skin showed decreased epidermal nuclear HMGB1 expression in upper epidermis vs. healthy or MPE skin but retained basal/suprabasal expression.

CONCLUSIONS

Epidermal HMGB1 expression was decreased in SJS/TEN skin. Retained basal/suprabasal epidermal HMGB1 expression may exacerbate localized injury in SJS/TEN.

Critical assessment of approaches for molecular docking to elucidate associations of HLA alleles with adverse drug reactions

•

All software assessed could dock Abacavir back into the risk allele structure but not always predict the exact binding mode.

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Most docking software assessed can distinguish between risk and control alleles.

•

Docking performance can be degraded by using a homology model.

•

Receptor flexibility can negatively affect the docking performance for complex HLA examples.

•

Using AutoDockFR cannot compensate for the added difficulty of docking to the unbound target.

Adverse drug reactions have been linked with genetic polymorphisms in HLA genes in numerous different studies. HLA proteins have an essential role in the presentation of self and non-self peptides, as part of the adaptive immune response. Amongst the associated drugs-allele combinations, anti-HIV drug Abacavir has been shown to be associated with the HLA-B*57:01 allele, and anti-epilepsy drug Carbamazepine with B*15:02, in both cases likely following the altered peptide repertoire model of interaction. Under this model, the drug binds directly to the antigen presentation region, causing different self peptides to be presented, which trigger an unwanted immune response. There is growing interest in searching for evidence supporting this model for other ADRs using bioinformatics techniques. In this study, in silico docking was used to assess the utility and reliability of well-known docking programs when addressing these challenging HLA-drug situations. The overall aim was to address the uncertainty of docking programs giving different results by completing a detailed comparative study of docking software, grounded in the MHC-ligand experimental structural data – for Abacavir and to a lesser extent Carbamazepine - in order to assess their performance. Four docking programs: SwissDock, ROSIE, AutoDock Vina and AutoDockFR, were used to investigate if each software could accurately dock the Abacavir back into the crystal structure for the protein arising from the known risk allele, and if they were able to distinguish between the HLA-associated and non-HLA-associated (control) alleles. The impact of using homology models on the docking performance and how using different parameters, such as including receptor flexibility, affected the docking performance were also investigated to simulate the approach where a crystal structure for a given HLA allele may be unavailable. The programs that were best able to predict the binding position of Abacavir were then used to recreate the docking seen for Carbamazepine with B*15:02 and controls alleles.

It was found that the programs investigated were sometimes able to correctly predict the binding mode of Abacavir with B*57:01 but not always. Each of the software packages that were assessed could predict the binding of Abacavir and Carbamazepine within the correct sub-pocket and, with the exception of ROSIE, was able to correctly distinguish between risk and control alleles. We found that docking to homology models could produce poorer quality predictions, especially when sequence differences impact the architecture of predicted binding pockets. Caution must therefore be used as inaccurate structures may lead to erroneous docking predictions. Incorporating receptor flexibility was found to negatively affect the docking performance for the examples investigated. Taken together, our findings help characterise the potential but also the limitations of computational prediction of drug-HLA interactions. These docking techniques should therefore always be used with care and alongside other methods of investigation, in order to be able to draw strong conclusions from the given results.

A Framework for Multi-Omic Prediction of Treatment Response to Biologic Therapy for Psoriasis

Biologic therapies have shown high efficacy in psoriasis, but individual response varies and is poorly understood. To inform biomarker discovery in the Psoriasis Stratification to Optimise Relevant Therapy (i.e., PSORT) study, we evaluated a comprehensive array of omics platforms across three time points and multiple tissues in a pilot investigation of 10 patients with severe psoriasis, treated with the tumor necrosis factor (TNF) inhibitor, etanercept. We used RNA sequencing to analyze mRNA and small RNA transcriptome in blood, lesional and nonlesional skin, and the SOMAscan platform to investigate the serum proteome. Using an integrative systems biology approach, we identified signals of treatment response in genes and pathways associated with TNF signaling, psoriasis pathology, and the major histocompatibility complex region. We found association between clinical response and TNF-regulated genes in blood and skin. Using a combination of differential expression testing, upstream regulator analysis, clustering techniques, and predictive modeling, we show that baseline samples are indicative of patient response to biologic therapies, including signals in blood, which have traditionally been considered unreliable for inference in dermatology. In conclusion, our pilot study provides both an analytical framework and empirical basis to estimate power for larger studies, specifically the ongoing PSORT study, which we show as powered for biomarker discovery and patient stratification.

Susceptibility to corticosteroid-induced adrenal suppression: a genome-wide association study

BACKGROUND

A serious adverse effect of corticosteroid therapy is adrenal suppression. Our aim was to identify genetic variants affecting susceptibility to corticosteroid-induced adrenal suppression.

METHODS

We enrolled children with asthma who used inhaled corticosteroids as part of their treatment from 25 sites across the UK (discovery cohort), as part of the Pharmacogenetics of Adrenal Suppression with Inhaled Steroids (PASS) study. We included two validation cohorts, one comprising children with asthma (PASS study) and the other consisting of adults with chronic obstructive pulmonary disorder (COPD) who were recruited from two UK centres for the Pharmacogenomics of Adrenal Suppression in COPD (PASIC) study. Participants underwent a low-dose short synacthen test. Adrenal suppression was defined as peak cortisol less than 350 nmol/L (in children) and less than 500 nmol/L (in adults). A case-control genome-wide association study was done with the control subset augmented by Wellcome Trust Case Control Consortium 2 (WTCCC2) participants. Single nucleotide polymorphisms (SNPs) that fulfilled criteria to be advanced to replication were tested by a random-effects inverse variance meta-analysis. This report presents the primary analysis. The PASS study is registered in the European Genome-phenome Archive (EGA). The PASS study is complete whereas the PASIC study is ongoing.

FINDINGS

Between November, 2008, and September, 2011, 499 children were enrolled to the discovery cohort. Between October, 2011, and December, 2012, 81 children were enrolled to the paediatric validation cohort, and from February, 2010, to June, 2015, 78 adults were enrolled to the adult validation cohort. Adrenal suppression was present in 35 (7%) children in the discovery cohort and six (7%) children and 17 (22%) adults in the validation cohorts. In the discovery cohort, 40 SNPs were found to be associated with adrenal suppression (genome-wide significance p<1 × 10-6), including an intronic SNP within the PDGFD gene locus (rs591118; odds ratio [OR] 7·32, 95% CI 3·15-16·99; p=5·8 × 10-8). This finding for rs591118 was validated successfully in both the paediatric asthma (OR 3·86, 95% CI 1·19-12·50; p=0·02) and adult COPD (2·41, 1·10-5·28; p=0·03) cohorts. The proportions of patients with adrenal suppression by rs591118 genotype were six (3%) of 214 patients with the GG genotype, 15 (6%) of 244 with the AG genotype, and 22 (25%) of 87 with the AA genotype. Meta-analysis of the paediatric cohorts (discovery and validation) and all three cohorts showed genome-wide significance of rs591118 (respectively, OR 5·89, 95% CI 2·97-11·68; p=4·3 × 10-9; and 4·05, 2·00-8·21; p=3·5 × 10-10).

INTERPRETATION

Our findings suggest that genetic variation in the PDGFD gene locus increases the risk of adrenal suppression in children and adults who use corticosteroids to treat asthma and COPD, respectively.

FUNDING

Department of Health Chair in Pharmacogenetics.

Biomarkers of adverse drug reactions

Adverse drug reactions can be caused by a wide range of therapeutics. Adverse drug reactions affect many bodily organ systems and vary widely in severity. Milder adverse drug reactions often resolve quickly following withdrawal of the casual drug or sometimes after dose reduction. Some adverse drug reactions are severe and lead to significant organ/tissue injury which can be fatal. Adverse drug reactions also represent a financial burden to both healthcare providers and the pharmaceutical industry. Thus, a number of stakeholders would benefit from development of new, robust biomarkers for the prediction, diagnosis, and prognostication of adverse drug reactions. There has been significant recent progress in identifying predictive genomic biomarkers with the potential to be used in clinical settings to reduce the burden of adverse drug reactions. These have included biomarkers that can be used to alter drug dose (for example, Thiopurine methyltransferase (TPMT) and azathioprine dose) and drug choice. The latter have in particular included human leukocyte antigen (HLA) biomarkers which identify susceptibility to immune-mediated injuries to major organs such as skin, liver, and bone marrow from a variety of drugs. This review covers both the current state of the art with regard to genomic adverse drug reaction biomarkers. We also review circulating biomarkers that have the potential to be used for both diagnosis and prognosis, and have the added advantage of providing mechanistic information. In the future, we will not be relying on single biomarkers (genomic/non-genomic), but on multiple biomarker panels, integrated through the application of different omics technologies, which will provide information on predisposition, early diagnosis, prognosis, and mechanisms. Impact statement • Genetic and circulating biomarkers present significant opportunities to personalize patient therapy to minimize the risk of adverse drug reactions. ADRs are a significant heath issue and represent a significant burden to patients, healthcare providers, and the pharmaceutical industry. • This review details the current state of the art in biomarkers of ADRs (both genetic and circulating). There is still significant variability in patient response which cannot be explained by current knowledge of genetic risk factors for ADRs; however, we discussed how specific advances in genomics have the potential to yield better and more predictive models. • Many current clinically utilized circulating biomarkers of tissue injury are valid biomarkers for a number of ADRs. However, they often give little insight into the specific cell or tissue subtype which may be affected. Emerging circulating biomarkers with potential to provide greater information on the etiology/pathophysiology of ADRs are described.

Genome-wide association study of nevirapine hypersensitivity in a sub-Saharan African HIV-infected population

Background

The antiretroviral nevirapine is associated with hypersensitivity reactions in 6%-10% of patients, including hepatotoxicity, maculopapular exanthema, Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN).

Objectives

To undertake a genome-wide association study (GWAS) to identify genetic predisposing factors for the different clinical phenotypes associated with nevirapine hypersensitivity.

Methods

A GWAS was undertaken in a discovery cohort of 151 nevirapine-hypersensitive and 182 tolerant, HIV-infected Malawian adults. Replication of signals was determined in a cohort of 116 cases and 68 controls obtained from Malawi, Uganda and Mozambique. Interaction with ERAP genes was determined in patients positive for HLA-C*04:01 . In silico docking studies were also performed for HLA-C*04:01 .

Results

Fifteen SNPs demonstrated nominal significance ( P  <   1 × 10 -5 ) with one or more of the hypersensitivity phenotypes. The most promising signal was seen in SJS/TEN, where rs5010528 ( HLA-C locus) approached genome-wide significance ( P  <   8.5 × 10 -8 ) and was below HLA -wide significance ( P  <   2.5 × 10 -4 ) in the meta-analysis of discovery and replication cohorts [OR 4.84 (95% CI 2.71-8.61)]. rs5010528 is a strong proxy for HLA-C*04:01 carriage: in silico docking showed that two residues (33 and 123) in the B pocket were the most likely nevirapine interactors. There was no interaction between HLA-C*04:01 and ERAP1 , but there is a potential protective effect with ERAP2 [ P  =   0.019, OR 0.43 (95% CI 0.21-0.87)].

Conclusions

HLA-C*04:01 predisposes to nevirapine-induced SJS/TEN in sub-Saharan Africans, but not to other hypersensitivity phenotypes. This is likely to be mediated via binding to the B pocket of the HLA-C peptide. Whether this risk is modulated by ERAP2 variants requires further study.

The molecular genetics of chemotherapy-induced peripheral neuropathy: A systematic review and meta-analysis

Chemotherapy-induced peripheral neuropathy (CIPN) can adversely affect completion of systemic anti-cancer treatment and cause long-term morbidity. Increasingly pharmacogenetic studies have been performed to explore susceptibility to this important adverse effect. A systematic review was conducted to identify pharmacogenetic studies, assess their quality and findings and undertake meta-analysis where possible. 93 studies were included. Notable methodological issues included lack of standardisation and detail in phenotype definition and acknowledgement of potential confounding factors. Insufficient data was presented in many studies meaning only a minority could be included in meta-analysis showing mainly non-significant effects. Nonetheless, SNPs in CYP2C8, CYP3A4, ARHGEF10, EPHA and TUBB2A genes (taxanes), FARS2, ACYP2 and TAC1 (oxaliplatin), and CEP75 and CYP3A5 (vincristine) are of potential interest. These require exploration in large cohort studies with robust methodology and well-defined phenotypes. Seeking standardisation of phenotype, collaboration and subsequently, individual-patient-data meta-analysis may facilitate identifying contributory SNPs which could be combined in a polygenic risk score to predict those most at risk of CIPN.

Advances in the Pharmacogenomics of Adverse Drug Reactions

Rapid developments in pharmacogenomics have been noticeable in recent years, and much of this knowledge has improved understanding of adverse drug reactions. This improved knowledge has largely been the result of improved sequencing technologies and falling costs in this area, as well as improved statistical techniques to analyse the data derived from studies. While the genetic reasons behind adverse drug reactions are becoming better understood, translation of this knowledge, particularly in terms of biomarkers that might be clinically applicable at the bedside, has been more difficult. Understanding of the technologies and their application is limited among practising clinicians. The cost of some of the technologies available may also be prohibitive in stretched healthcare economies. As education about the potential for applying pharmacogenomics improves and costs fall, understanding of adverse drug reactions and application of this knowledge in a clinical setting should improve.

7th drug hypersensitivity meeting: part one

Oral Abstracts

O1 Functionally distinct HMGB1 isoforms correlate with physiological processes in drug-induced SJS/TEN

Daniel F. Carr, Wen-Hung Chung, Rosalind E. Jenkiins, Mas Chaponda, Gospel Nwikue, Elena M. Cornejo Castro, Daniel J. Antoine, Munir Pirmohamed

O2 Hypersensitivity reactions to beta-lactams, does the t cell recognition pattern influence the clinical picture?

Natascha Wuillemin, Dolores Dina, Klara K. Eriksson, Daniel Yerly

O3 Specific binding characteristics of HLA alleles associated with nevirapine hypersensitivity

Rebecca Pavlos, Elizabeth Mckinnin, David Ostrov, Bjoern Peters, Soren Buus, David Koelle, Abha Chopra, Craig Rive, Alec Redwood, Susana Restrepo, Austin Bracey, Jing Yuan, Silvana Gaudieri, Mary Carrington, David Haas, Simon Mallal, Elizabeth Phillips

O4 Do we need to measure total ige for the interpretation of analytical results of ImmunoCAP dnd 3gAllergy specific IgE?

Douwe De Boer, Paul Menheere, Chris Nieuwhof, Judith Bons

O5 Neutrophil activation in systemic anaphylaxis: results from the multicentric NASA study

Friederike Jonsson, Luc De Chaisemartin, Vanessa Granger, Caitlin Gillis, Aurelie Gouel, Catherine Neukirch, Fadia Dib, Pascale Roland Nicaise, Dan Longrois, Florence Tubach, Sylvie Martin, Pierre Bruhns, NASA Study Group

O6 Purpuric drug eruptions due to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) for non-small-cell lung cancer (NSCLC): a clinic-pathological study of 32 cases

Kai-Lung Chen, Shu-Ling Liao, Yi-Shuan Sheen, Yung-Tsu Cho, Che-Wen Yang, Jau-Yu Liau, Chia-Yu Chu

Poster presentations: Poster Walk 1—Anaphylaxis (P01–P09)

P1 Anaphylactic reactions during anaesthesia and the perioperative period

Rita Aguiar, Anabela Lopes, Natália Fernandes, Leonor Viegas, M. A. Pereira-Barbosa

P2 Anaphylaxis to chlorhexidine: is there a cross-reactivity to alexidine?

Antonia Bünter, Nisha Gupta, Tatjana Pecaric Petkovic, Nicole Wirth, Werner J. Pichler, Oliver Hausmann

P3 Cefotaxime-induced severe anaphylaxis in a neonate

Mehtap Yazicioglu, Pinar G. Ozdemir, Gokce Ciplak, Ozkan Kaya

P4 Clinical features and diagnosis of anaphylaxis resulting from exposure to chlorhexidine

Peter John Cooke

P5 Drug-induced anaphylaxis: five-year single-center survey

Inês Mota, Ângela Gaspar, Filipe Benito-Garcia, Marta Chambel, Mário Morais-Almeida

P6 Intraoperative severe anaphylactic reaction due to patent blue v dye

Luis Marques, Eva Alcoceba, Silvia Lara

P7 Kounis syndrome in the setting of anaphylaxis to diclofenac

Leonor Carneiro-Leão, Carmen Botelho, Eunice Dias-Castro, Josefina Cernadas

P8 Perioperative anaphylaxis audit: Royal Melbourne Hospital

Katherine Nicholls, William Lay, Olivia Smith, Christine Collins, Gary Unglik, Kymble Spriggs, Priscilla Auyeung, Jeremy McComish, Jo A. Douglass

P9 Recurrent peri-operative anaphylaxis: a perfect storm

Jonny G. Peter, Paul Potter

Poster Walk 2: DH regions and patient groups (P10–P19)

P10 A rare presentation of amoxicillin allergy in a young child

Fabrícia Carolino, Eunice Dias De Castro, Josefina R. Cernadas

P11 Adverse drug reactions in children: antibiotics or virus?

Ana Sofia Moreira, Carmo Abreu, Eva Gomes

P12 Allergic reactions in invasive medical procedures

Bárbara Kong Cardoso, Elza Tomaz, Sara Correia, Filipe Inácio

P13 Antibiotic allergy in children: room for improvement

Annabelle Arnold, Natasha Bear, Kristina Rueter, Grace Gong, Michael O’Sullivan, Saravanan Muthusamy, Valerie Noble, Michaela Lucas

P14 Drug hypersensitivity reactions in children and results of diagnostic evaluation

Neringa Buterleviciute, Odilija Rudzeviciene

P15 Nonimmediate cutaneous drug reactions in children: are skin tests required?

Ana Sofia Moreira, Carmo Abreu, Eva Gomes

P16 Pediatric patients with a history of penicillin allergy and a positive penicillin skin test may not be at an increased risk for multiple drug allergies

Sara May, Thanai Pongdee, Miguel Park

P17 Proved hypersensitivity to drugs according data of Vilnius University Hospital Santariskiu Klinikos

Linas Griguola, Arturas Vinikovas, Simona Kašinskaite, Violeta Kvedariene

P18 Self-reported prevalence of drug hypersensitivity reactions among students in Celal Bayar University, Turkey

Ayse Aktas, Suheyla Rahman, Huseyin Elbi, Beyhan Cengiz Ozyurt

P19 Severe drug hypersensitivity reactions in pediatric age

Ozlem Cavkaytar, Betul Karaatmaca, Pinar Gur Cetinkaya, Saliha Esenboga, Umit M. Sahiner, Bulent E. Sekerel, Ozge Soyer

Poster Walk 3: Desensitisation (P20–P28)

P20 A protocol for desensitisation to valaciclovir

Celia Zubrinich, Bianca Tong, Mittal Patel, Michelle Giles, Robyn O’Hehir, Robert Puy

P21 A rare case of desensitization to modafinil

Josefina Cernadas, Luís Amaral, Fabrícia Carolino

P22 A sixteen-day desensitization protocol in delayed type hypersensitivity reactions to oral drugs

Semra Demir, Asli Gelincik, Muge Olgac, Raif Caskun, Derya Unal, Bahauddin Colakoglu, Suna Buyukozturk

P23 Desensitization to intravenous etoposide using a 12 and a 13-step protocol. Two cases report

Olga Vega Matute, Amalia Bernad, Gabriel Gastaminza, Roselle Madamba, Carlos Lacasa, M. J. Goikoetxea, Carmen D’Amelio, Jose Rifón, Nicolas Martínez, Marta Ferrer

P24 Drug desensitisation in oncology: the experience of an immunoallergology department for 5 years

Carmelita Ribeiro, Emília Faria, Cristina Frutuoso, Anabela Barros, Rosário Lebre, Alice Pego, Ana Todo Bom

P25 Filgrastim anaphylaxis: a successful desensitization protocol

Luis Amaral, Josefina Cernadas

P26 Galsulfase hypersensitivity and desensitization of a mucopolysaccharidosis VI patient

Luis Felipe Ensina, Carolina Aranda, Ines Camelo Nunes, Ana Maria Martins, Dirceu Solé

P27 Rapid drug desensitization with biologicals: one-center experience with four biologicals

Sevim Bavbek, Resat Kendirlinan, Pamir Çerçi, Seda Tutluer, Sadan Soyyigit, Zeynep Çelebi Sözener, Ömür Aydin, Reyhan Gümüsburun

P28 Successful desensitization to a high dose of methotrexate in a delayed type hypersensitivity reaction

Josefina Cernadas, Leonor Carneiro-Leão, Fabrícia Carolino, Marta Almeida

Poster Walk 4: SJS (P29–P38)

P29 Assessment of impact of infection on drug-induced severe cutaneous adverse reactions and rhabdomyolysis using the Japanese adverse drug event report database

Kimie Sai, Takuya Imatoh, Ryosuke Nakamura, Chisato Fukazawa, Yasushi Hinomura, Yoshiro Saito

P30 Characterization of erythema multiforme and severe cutaneous adverse reactions hospitalizations

Bernardo Sousa-Pinto, Cláudia Correia, Lídia Gomes, Sara Gil-Mata, Luís Araújo, Luís Delgado

P31 Effects of infection on incidence/severity of SJS/TEN and myopathy in Japanese cases analyzed by voluntary case reports

Ryosuke Nakamura, Kimie Sai, Takuya Imatoh, Yoshimi Okamoto-Uchida, Koji Kajinami, Kayoko Matsunaga, Michiko Aihara, Yoshiro Saito

P32 Efficacy of tumor necrosis factor—a antagonists in Stevens–Johnson syndrome and toxic epidermal necrolysis: a randomized controlled trial and immunosuppressive effects evaluation

Chuang-Wei Wang, Shih-Chi Su, Shuen-Iu Hung, Hsin-Chun Ho, Chih-Hsun Yang, Wen-Hung Chung

P33 Evolution of drug causality in Stevens–Johnson syndrome and toxic epidermal necrolysis in Europe: analysis of 10 years RegiSCAR-Study

Maren Paulmann, Ariane Dunant, Maja Mockenhaupt, Peggy Sekula, Martin Schumacher, Sylvia Kardaun, Luigi Naldi, Teresa Bellón, Daniel Creamer, Cynthia Haddad, Bruno Sassolas, Bénédicte Lebrun-Vignes, Laurence Valeyrie-Allanore, Jean-Claude Roujeau

P34 Long-term sequelae in patients with Stevens–Johnson syndrome and toxic epidermal necrolysis: a 5-year analysis

Maren Paulmann, Carmen Kremmler, Peggy Sekula, Laurence Valeyrie-Allanore, Luigi Naldi, Sylvia Kardaun, Maja Mockenhaupt

P35 Major emotional complications and decreased health related quality of life among survivors of Stevens–Johnson syndrome and toxic epidermal necrolysis

Roni P. Dodiuk-Gad, Cristina Olteanu, Anthony Feinstein, Rena Hashimoto, Raed Alhusayen, Sonia Whyte-Croasdaile, Yaron Finkelstein, Marjorie Burnett, Shachar Sade, Robert Cartotto, Marc Jeschke, Neil H. Shear

P36 Retrospective analysis of Stevens–Johnson syndrome and toxic epidermal necrolysis in Japanese patients: treatment and outcome

Naoko Takamura, Yumiko Yamane, Setsuko Matsukura, Kazuko Nakamura, Yuko Watanabe, Yukie Yamaguchi, Takeshi Kambara, Zenro Ikezawa, Michiko Aihara

P37 Severe physical complications among survivors of Stevens–Johnson syndrome and toxic epidermal necrolysis

Roni P. Dodiuk-Gad, Cristina Olteanu, Rena Hashimoto, Hall Chew, Raed Alhusayen, Sonia Whyte-Croasdaile, Yaron Finkelstein, Marjorie Burnett, Shachar Sade, Robert Cartotto, Marc Jeschke, Neil H. Shear

P38 Stevens–Johnson syndrome/toxic epidermal necrolysis combined with haemophagocytic lymphohistiocytosis: a case report

Brittany Knezevic, Una Nic Ionmhain, Allison Barraclough, Michaela Lucas, Matthew Anstey

Poster Walk 5: Other organs/unexpected immune reactions (P39–P47)

P39 A case report of patient with anti-tuberculosis drug-related severe liver failure

Toru Usui, Xiaoli Meng, John Farrell, Paul Whitaker, John Watson, Neil French, Kevin Park, Dean Naisbitt

P40 Acute interstitial nephritis induced by ibuprofen

Ana Castro Neves, Susana Cadinha, Ana Moreira, J. P. Moreira Da Silva

P41 Cetuximab induced acneiform rash—two case reports

Daniela Ledic Drvar, Sandra Jerkovic Gulin, Suzana Ljubojevic Hadzavdic, Romana Ceovic

P42 Enteropathy associated with losartan

Ana Montoro De Francisco, Talía De Vicente Jiménez, Amelia García Luque, Natalia Rosado David, José Mª Mateos Galván

P43 Granuloma annulare after therapy with canakinumab

Razvigor Darlenski

P44 Hypersensitivity eosinophilic myocarditis or acute coronary syndrome? Case report

Dario Gulin, Jozica Sikic, Jasna Cerkez Habek, Sandra Jerkovic Gulin, Edvard Galic

P45 Piperacillin-induced immune haemolytic anaemia: a severe and frequent complication of antibiotic treatment in patients with cystic fibrosis

Philip Specht, Doris Staab, Beate Mayer, Jobst Roehmel

P46 Progesterone triggered pemphigus foliaceus: case report

Sandra Jerkovic Gulin, Caius Solovan, Anca Chiriac

P47 Ramipril: triggered generalized pustular psoriasis

Paola Djurinec, Kresimir Kostovic, Mirna Bradamante, Sandra Jerkovic Gulin, Romana Ceovic

Poster Walk 6: NSAIDs (P48–P56)

P48 Aspirin desensitization in cardiovascular disease—Portuguese experience

Jose Pedro Almeida, Joana Caiado, Elisa Pedro, Pedro Canas Da Silva, Manuel Pereira Barbosa

P49 Asthma and/or rhinitis to NSAIDs with good tolerance to ASA

Gador Bogas, Natalia Blanca-López, Diana Pérez-Alzate, Inmaculada Doña, José Augusto Agúndez, Elena García-Martín, José Antonio Cornejo-García, Cristobalina Mayorga, María José Torres, Gabriela Canto, Miguel Blanca

P50 Clinical characteristics of 196 patients with non-steroidal anti-inflammatory drug (NSAIDs) hypersensitivity

Sengül Aksakal, Aytül Zerrin Sin, Zeynep Peker Koç, Fatma Düsünür Günsen, Ömür Ardeniz, Emine Nihal Mete Gökmen, Okan Gülbahar, Ali Kokuludag

P51 Development of immediate hypersensitivity to several NSAIDs maintaining good tolerance to ASA

Natalia Pérez-Sánchez, Natalia Blanca-López, Diana Pérez-Alzate, Gador Bogas, Inmaculada Doña, María Salas, María José Torres, Miguel Blanca, Gabriela Canto

P52 Diagnosis of hypersensitivity reactions to paracetamol in a large series of cases

Inmaculada Doña, Maria Salas, Francisca Gomez, Natalia Blanca-Lopez, Diana Perez-Alzate, Gador Bogas, Esther Barrionuevo, Maria Jose Torres, Inmaculada Andreu, Miguel Ángel Miranda, Gabriela Canto, Miguel Blanca

P53 Hypersensitivity to paracetamol according to the new classification of hypersensitivity to NSAIDs

Gabija Didžiokaite, Olesia Gaidej, Simona Kašinskaite, Violeta Kvedariene

P54 Ibuprofen and other aryl propionic derivates can induce immediate selective hypersensitivity responses

Diana Perez-Alzate, Natalia Blanca-López, Maria Isabel Garcimartin, Inmaculada Doña, Maria Luisa Somoza, Cristobalina Mayorga, Maria Jose Torres, Gador Bojas, Jose Antonio Cornejo-Garcia, Maria Gabriela Canto, Miguel Blanca

P55 Subjects developing immediate responses to several NSAIDs can be selective with good tolerance to ASA

Natalia Blanca-Lopez, Diana Pérez-Alzate, Francisco Javier Ruano Perez, Inmaculada Doña, Maria Luisa Somoza, Inmaculada Andreu, Miguel Angel Miranda, Cristobalina Mayorga, Maria Jose Torres, Jose Antonio Cornejo-Garcia, Miguel Blanca, Maria Gabriela Canto

P56 Utility of low-dose oral aspirin challenges for diagnosis of aspirin exacerbated respiratory disease

Elina Jerschow, Teresa Pelletier, Zhen Ren, Golda Hudes, Marek Sanak, Esperanza Morales, Victor Schuster, Simon D. Spivack, David Rosenstreich

Poster Walk 7: NSAID 2 (P57–P65)

P57 Alternate regulation of cyclooxygenase-2 (COX-2) MRNA expression may predispose patients to aspirin-induced exacerbations

Renato Erzen, Mira Silar, Nissera Bajrovic, Matija Rijavec, Mihaela Zidarn, Peter Korosec

P58 Anaphylaxis to diclofenac: what about the underlying mechanism?

Leonor Carneiro-Leão, Fabrícia Carolino, Luís Amaral, Carmen Botelho, Eunice Dias-Castro, Josefina Cernadas

P59 COX-2 inhibitors: are they always a safe alternative in hypersensitivity to nonsteroidal anti-inflammatory drugs?

Luis Amaral, Fabricia Carolino, Eunice Castro, Josefina Cernadas

P60 Management of patients with history of NSAIDs reactions prior to coronary angioplasty

Mona Al-Ahmad, Tito Rodriguez

P61 Oral drug challenge with non-steroidal anti-inflammatory drug under spirometric control: clinical series of 110 patients

João Pedro Azevedo, Emília Faria, Beatriz Tavares, Frederico Regateiro, Ana Todo-Bom

P62 Prevalence and incidence of analgesic hypersensitivity reactions in Colombia

Pablo Andrés Miranda, Bautista De La Cruz Hoyos

P63 Recent endoscopic sinus surgery lessens reactions during aspirin challenge in patients with aspirin exacerbated respiratory disease

Teresa Pelletier, Waleed Abuzeid, Nadeem Akbar, Marc Gibber, Marvin Fried, Weiguo Han, Taha Keskin, Robert Tamayev, Golda Hudes, Simon D. Spivack, David Rosenstreich, Elina Jerschow

P64 Safe use of imidazole salycilate in a case of multiple NSAIDs induced urticaria-angioedema

Elisa Boni, Marina Russello, Marina Mauro

P65 Selective hypersensitivity reactions to ibuprofen—seven years experience

Marta Ferreira Neto

Poster Walk 8: Epidemiological methods (P66–P72)

P66 Allopurinol hypersensitivity: a 7-year review

Lise Brosseron, Daniela Malheiro, Susana Cadinha, Patrícia Barreira, J. P. Moreira Da Silva

P67 Antibiotic allergy labelling is associated with increased hospital readmission rates in Australia

Brittany Knezevic, Dustin Sprigg, Michelle Trevenen, Jason Seet, Jason Trubiano, William Smith, Yogesh Jeelall, Sandra Vale, Richard Loh, Andrew Mclean-Tooke, Michaela Lucas

P68 Experts’ opinions on severe cutaneous adverse drug reactions-report of a survey from the 9th international congress on cutaneous adverse drug reactions 2015

Roni P. Dodiuk-Gad, Cristina Olteanu, Wen-Hung Chung, Neil H. Shear

P69 HLA-A*31-positive AGEP with carbamazepine use and other severe cutaneous adverse drug reactions (SCARs) detected by electronic medical records screening

Sabine Müller, Ursula Amstutz, Lukas Jörg, Nikhil Yawalkar, Stephan Krähenbühl

P70 Patients with suspected drug allergy: a specific psychological profile?

Eunice Dias-Castro, Ana Leblanc, Laura Ribeiro, Josefina R. Cernadas

P71 Use of an electronic device and a computerized mathematic algorithm to detect the allergic drug reactions through the analysis of heart rate variability

Arantza Vega, Raquel Gutierrez Rivas, Ana Alonso, Juan Maria Beitia, Belén Mateo, Remedios Cárdenas, Juan Jesus Garcia-Dominguez

P72 Variation in ERAP influences risk for HLA-B*57:01 positive abacavir hypersensitivity

Rebecca Pavlos, Kaija Strautins, Ian James, Simon Mallal, Alec Redwood, Elizabeth Phillips

Poster Walk 9: DRESS/AGEP (P73–P81)

P73 A clinical case of DRESS syndrome in a child after administration of amoxicillin-clavulanic acid

Rita Aguiar, Anabela Lopes, Ana Neves, Maria Do Céu Machado, M. A. Pereira-Barbosa

P74 Acute generalized exanthematous pustulosis (AGEP) induced by mesalazine, reliable and oftenly used drug to treat inflammatory bowel disease

Ceyda Tunakan Dalgiç, Emine Nihal Mete Gökmen, Fatma Düsünür Günsen, Gökten Bulut, Fatma Ömür Ardeniz, Okan Gülbahar, Ali Kokuludag, Aytül Zerrin Sin

P75 Changes of blood plasmacytoid dendritic cells, myeloid dendritic cells, and basophils during the acute stage of drug reaction with eosinophilia and systemic symptoms (DRESS) and other drug eruptions

Shao-Hsuan Hsu, Yung-Tsu Cho, Che-Wen Yang, Kai-Lung Chen, Chia-Yu Chu

P76 Characterization of isoniazid/rifampicin-specific t-cell responses in patients with DRESS syndrome

Young-Min Ye, Gyu-Young Hur, Hae-Sim Park, Seung-Hyun Kim

P77 DRESS syndrome secondary to sulfasalazine with delayed TEN: a case presentation

Syed Ali, Michaela Lucas, Peter N. Hollingsworth, Andrew P. C. Mclean-Tooke

P78 Drug rash with eosinophilia and systemic symptoms (DRESS) features according to the culprit drug

Zohra Chadly, Nadia Ben Fredj, Karim Aouam, Haifa Ben Romdhane, Naceur A. Boughattas, Amel Chaabane

P79 Drug reaction with eosinophilia and systemic symptoms induced by allopurinol: not always easy to diagnose

Marina Lluncor Salazar, Beatriz Pola, Ana Fiandor, Teresa Bellón, Elena Ramírez, Javier Domínguez Ortega, Santiago Quirce, Rosario Cabañas

P80 Drug reaction with eosinophilia and systemic symptoms syndrome induced by two drugs simultaneously: a case report

Krasimira Baynova, Marina Labella, Manuel Prados

P81 The drug reaction with eosinophilia and systemic symptoms (DRESS) induced by the second-line antituberculosis drugs and Epstein–Barr virus infection

Agne Ramonaite, Ieva Bajoriuniene, Brigita Sitkauskiene, Raimundas Sakalauskas

Poster Walk 10: Miscellaneous drug hypersensitivity (P82–P91)

P82 A case of cycloserine-induced lichenoid drug eruption confirmed with a lymphocatye transformation test

Jae-Woo Kwon, Shinyoung Park

P83 Allergic reaction to topical eye drops: 5 years’ retrospective study in a drug allergy unit

Diana Silva, Leonor Carneiro Leão, Fabricia Carolino, Eunice Castro, Josefina Cernadas

P84 Allergy to heparins

Diana Perez-Alzate, Natalia Blanca-López, Maria Luisa Somoza Alvarez, Maria Garcimartin, Maria Vazquez De La Torre, Francisco Javier Ruano Pérez, Elisa Haroun, Gabriela Canto Diez

P85 Allopurinol-induced adverse drug reactions

Katinka Ónodi-Nagy, Ágnes Kinyó, Lajos Kemény, Zsuzsanna Bata-Csörgo

P86 Analysis of a population with immediate hypersensitivity to corticosteroids: an 11 year review

Joana Sofia Pita, Emília Faria, Rosa Anita Fernandes, Ana Moura, Nuno Sousa, Carmelita Ribeiro, Carlos Loureiro, Ana Todo Bom

P87 Anaphylaxis against mivacurium in a 12-months old boy at first-time exposure

Wolfgang Pfützner

P88 Antihistamine-exacerbated chronic spontaneous urticaria: a paradox?

Nadine Marrouche, Clive Grattan

P89 Anti-osteoporotic agents-induced cutaneous adverse drug reactions in Asians

Yu-En Chen, Chun-Bing Chen, Wen-Hung Chung, Yu-Ping Hsiao, Chia-Yu Chu

P90 Diagnosis of allergic reactions to eye drops

Maria Vazquez De La Torre, Natalia Blanca-Lopez, Diana Perez-Alzate, Maria Isabel Garcimartin, Francisco Javier Ruano, Maria Luisa Somoza, Elisa Haroun, Gabriela Canto

P91 Diagnostic approach in suspected hypersensitivity reactions to corticosteroids

Fabrícia Carolino, Eunice Dias De Castro, Josefina R. Cernadas

Efavirenz and Metabolites in Cerebrospinal Fluid: Relationship with CYP2B6 c.516G→T Genotype and Perturbed Blood-Brain Barrier Due to Tuberculous Meningitis

Efavirenz (EFZ) has been associated with neuropsychiatric side effects. Recently, the 8-hydroxy-EFZ (8OH-EFZ) metabolite has been shown to be a potent neurotoxin in vitro, inducing neuronal damage at concentrations of 3.3 ng/ml. EFZ induced similar neuronal damage at concentrations of 31.6 ng/ml. We investigated the effect of genotype and blood-brain barrier integrity on EFZ metabolite concentrations in cerebrospinal fluid (CSF). We measured CSF drug concentrations in subjects from two separate study populations: 47 subjects with tuberculous meningitis (TBM) coinfection in Vietnam receiving 800 mg EFZ with standard antituberculous treatment and 25 subjects from the PARTITION study in the United Kingdom without central nervous system infection receiving 600 mg EFZ. EFZ and metabolite concentrations in CSF and plasma were measured and compared with estimates of effectiveness and neurotoxicity from available published in vitro and in vivo data. The effect of the CYP2B6 c.516G→T genotype (GG genotype, fast EFV metabolizer status; GT genotype, intermediate EFV metabolizer status; TT genotype, slow EFV metabolizer status) was examined. The mean CSF concentrations of EFZ and 8OH-EFZ in the TBM group were 60.3 and 39.3 ng/ml, respectively, and those in the no-TBM group were 15.0 and 5.9 ng/ml, respectively. Plasma EFZ and 8OH-EFZ concentrations were similar between the two groups. CSF EFZ concentrations were above the in vitro toxic concentration in 76% of samples (GG genotype, 61%; GT genotype, 90%; TT genotype, 100%) in the TBM group and 13% of samples (GG genotype, 0%; GT genotype, 18%; TT genotype, 50%) in the no-TBM group. CSF 8OH-EFZ concentrations were above the in vitro toxic concentration in 98% of the TBM group and 87% of the no-TBM group; levels were independent of genotype but correlated with the CSF/plasma albumin ratio. Potentially neurotoxic concentrations of 8OH-EFZ are frequently observed in CSF independently of the CYP2B6 genotype, particularly in those with impaired blood-brain barrier integrity.

Predictors and outcomes of increases in creatine phosphokinase concentrations or rhabdomyolysis risk during statin treatment

AIM

The aim was to evaluate clinical risk factors associated with myotoxicity in statin users.

METHODS

This was a cohort study of patients prescribed a statin in UK primary care practices contributing to the Clinical Practice Research Datalink. Outcomes of interest were creatine phosphokinase (CPK) concentrations and clinical records of rhabdomyolysis.

RESULTS

The cohort comprised 641,703 statin users. Simvastatin was most frequently prescribed (66.3%), followed by atorvastatin (24.4%). CPK was measured in 127,209 patients: 81.4% within normal range and 0.7% above <four times the upper limit of normal (ULN). Rhabdomyolysis was recorded in 59 patients. Patients with concomitant prescribing of CYP3A4-interacting drugs had an increased odds ratio (OR) of rhabdomyolysis compared with controls (OR 3.71, 95% CI 1.18, 11.61) and >four times ULN CPK compared with normal CPK (OR 1.28, 95% CI 1.01, 1.60). Rosuvastatin users had higher risk of >four times ULN CPK (OR 1.62, 95% CI 1.22, 2.15) as did patients with larger daily doses of other statin types. A recent clinical record of myalgia was associated with an increased OR of >four times ULN CPK (OR 1.73, 95% CI 1.37, 2.18). In patients who were rechallenged to statins and had repeat CPK measurements after >four times ULN CPK abnormalities, 54.8% of the repeat CPK values were within normal range, 32.1% between one to three times and 13.0% >four times ULN.

CONCLUSIONS

The frequencies of substantive CPK increases and rhabdomyolysis during statin treatment were low, with highest risks seen in those on large daily doses or interacting drugs and on rosuvastatin. CPK measurements appeared to have been done in a haphazard manner and better guidance is needed.

Electronic health records for biological sample collection: feasibility study of statin-induced myopathy using the Clinical Practice Research Datalink

AIMS

Electronic healthcare records (EHRs) are increasingly used to store clinical information. A secondary benefit of EHRs is their use, in an anonymized form, for observational research. The Clinical Practice Research Datalink (CPRD) contains EHRs from primary care in the UK and, despite 1083 peer-reviewed research publications, has never been used to obtain pharmacogenetic samples. Using a statin-induced myopathy paradigm, we evaluated using the CPRD to obtain patient samples for a pharmacogenetic study targeting 250 cases and 500 controls from UK general practitioner (GP) practices.

METHODS

The CPRD identified potential patients fitting specific case-definition criteria (active rhabdomyolysis or creatine phosphokinase > four times the upper limit of normal), and corresponding GP practices were asked to invite patient participation. Consenting patients were requested to provide either saliva or blood samples and to complete an ethnicity questionnaire. Control subjects were recruited from the same GP practice (saliva) or a small number of practices (blood). Samples were forwarded for DNA extraction.

RESULTS

Thirty-six months of recruitment yielded DNA samples from 149 statin-induced myopathy cases and 587 tolerant controls. Data show that contacting patients through their GP is a reliable method for obtaining samples without compromising anonymity. Saliva collection directly from patients was considerably less effective than blood sampling. After 10 months of recruitment, saliva sampling was suspended in favour of blood sampling.

CONCLUSIONS

We demonstrate the potential of EHRs for identifying accurately phenotyped cases and controls for pharmacogenetic studies. Recruitment was successful only because of the willingness of GP practices to participate and the existence of strong doctor–patient relationships. The present study provides a model that can be implemented in future genetic analyses using EHRs.

Phenotype standardization for statin-induced myotoxicity

Statins are widely used lipid-lowering drugs that are effective in reducing cardiovascular disease risk. Although they are generally well tolerated, they can cause muscle toxicity, which can lead to severe rhabdomyolysis. Research in this area has been hampered to some extent by the lack of standardized nomenclature and phenotypic definitions. We have used numerical and descriptive classifications and developed an algorithm to define statin-related myotoxicity phenotypes, including myalgia, myopathy, rhabdomyolysis, and necrotizing autoimmune myopathy.

CYP2B6 c.983T>C polymorphism is associated with nevirapine hypersensitivity in Malawian and Ugandan HIV populations

Background

Nevirapine, an NNRTI used in HIV treatment, can cause hypersensitivity reactions in 6%–10% of patients. In the most serious cases (1.3%) this can manifest as Stevens–Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN).

Methods

DNA samples were obtained and analysed from a total of 209 adult patients with nevirapine hypersensitivity (57 from a prospective cohort and 152 routine clinic patients) and compared with 463 control patients on nevirapine without any hypersensitivity. The case group included 70 patients with SJS/TEN. All individuals were genotyped for two SNPs in the CYP2B6 gene [c.516G>T (CYP2B6*9) and c.983T>C (CYP2B6*18)] using the TaqMan real-time genotyping platform. The replication cohort comprised 29 controls and 55 nevirapine hypersensitive patients, including 8 SJS/TEN cases.

Results

An association between the CYP2B6 c.983T>C polymorphism and nevirapine-induced SJS/TEN was observed. In the SJS/TEN group, 30% of individuals possessed at least one c.983T>C versus 16% in the tolerant group [P = 0.006; OR (95% CI) 2.24 (1.27–3.94)]. This association was not significant in the replication cohort [P = 0.075; OR (95% CI) 4.33 (0.80–23.57)]. Combined analysis resulted in an OR of 2.52 (95% CI 1.48–4.20; P = 0.0005) for the association of c.983T>C with SJS/TEN. No association was observed for c.983T>C with other hypersensitivity phenotypes and for CYP2B6 c.516G>T with any hypersensitivity phenotypes.

Conclusions

Our data show an association between the c.983T>C polymorphism and nevirapine-induced SJS/TEN. CYP2B6 c.983T>C has a frequency of 5%–10% in a variety of African populations, but is not observed in Caucasians, thus representing an ethnic-specific predisposing factor.

Hepatic activation of irinotecan predicts tumour response in patients with colorectal liver metastases treated with DEBIRI: exploratory findings from a phase II study

PURPOSE

The response of colorectal liver metastases to the cytotoxic agent irinotecan varies widely. Attempts to correlate tumour metabolism with response have been mixed. This study investigated the hepatic metabolism of irinotecan as a potential predictor of tumour response to irinotecan-eluting beads (DEBIRI).

METHODS

Ten patients with colorectal liver metastases were treated with 200 mg irinotecan (as DEBIRI) as part of the PARAGON II study. Hepatic expression of key metabolising enzymes was measured using mass spectrometry-based proteomics. Serum drug concentrations and hepatic irinotecan metabolism were characterised and correlated with tumour response.

RESULTS

Serum concentrations of irinotecan metabolites did not correlate with hepatic metabolism or pathological response. There was a strong correlation between hepatic CES-2 expression and activation of irinotecan (r (2) = 0.96, p < 0.001). Patients with a UGT1A1*28 6/7 SNP showed no difference in drug metabolism or pathological response. Hepatic CES-2 mediated activation of irinotecan clearly correlated with tumour replacement by fibrosis (r (2) = 0.54, p = 0.01).

CONCLUSION

This study provides the first evidence that hepatic activation of irinotecan predicts tumour response. Delivery of liver-targeted irinotecan to normal liver tissue rather than tumour may be a more rational approach to maximise response.

Institutional Profile: The Wolfson Centre for Personalised Medicine, University of Liverpool, Liverpool, UK

The Wolfson Centre for Personalised Medicine is part of the Institute of Translational Medicine at the University of Liverpool (Liverpool, UK). It houses a multidisciplinary team of personalized medicine researchers engaged in collaborative research with partners across the globe. The primary focus of the centre is the identification of predictive biomarkers of drug safety and efficacy with the aim of translation from ‘bench-to-bedside’. Studies utilizing the latest genotyping and phenotyping, and point-of-care technologies, are undertaken with the ultimate aim of developing easy access for patients to truly personalized medicine. In addition to translation into clinical practice, the Centre puts significant emphasis into education of clinicians and scientists alike, as well as public engagement activities to promote personalized medicine.

Association of human leukocyte antigen alleles and nevirapine hypersensitivity in a Malawian HIV-infected population

Human leukocyte antigen genotyping of 272 Malawian HIV patients receiving nevirapine-containing regimens (of whom 117 had nevirapine hypersensitivity) has shown that HLA-C*04:01 increases the risk of Stevens-Johnson syndrome/toxic epidermal necrolysis, with an odds ratio of 5.17 (95% confidence interval, 2.39–11.18).

Background. The nonnucleoside reverse transcriptase inhibitor nevirapine is the cornerstone of treatment for human immunodeficiency virus (HIV) in many sub-Saharan African countries. However, nevirapine is associated with a 6%–10% risk of developing a hypersensitivity reaction, with different phenotypes, including the blistering conditions Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Our aim was to identify predictive human leukocyte antigen (HLA) markers that are associated with nevirapine hypersensitivity.

Methods. We identified 117 HIV-infected Malawian adults with nevirapine hypersensitivity (15 drug-induced liver injury [DILI], 33 SJS/TEN, 20 hypersensitivity syndrome, and 46 nevirapine-induced rash plus 3 with both DILI and SJS phenotype) and 155 age-, sex- and ethnicity-matched nevirapine-exposed controls. HLA typing for 5 loci (A, B, C, DRB1, and DQB1) was undertaken using a sequence-based high-resolution protocol. Logistic regression analysis included CD4⁺ cell count as a covariate.

Results. HLA-C*04:01 was found to markedly increase the risk for SJS (odds ratio [OR] = 17.52; 95% confidence interval, 3.31–92.80) and all hypersensitivity phenotypes (OR = 2.64; 95% CI, 1.13–6.18) when compared to the baseline rare allele group in a binary logistic regression model. The OR for absolute risk of SJS/TEN associated with carriage of HLA-C*04:01 was 5.17 (95% CI, 2.39–11.18). Positive predictive value was 2.6% and negative predictive value was 99.2%. In addition, a number of alleles within the HLA-DQB1 loci protected against nevirapine-induced hypersensitivity phenotypes.

Conclusions. Our study has identified HLA-C*04:01 carriage as a risk factor for nevirapine-induced SJS/TEN in a Malawian HIV cohort. Validation of these findings in a larger cohort of patients and mechanistic investigation of the pathogenesis are required.

Conference Scene: Report on the 8th Annual Cold Spring Harbor/Wellcome Trust meeting on Pharmacogenomics and Personalized Medicine

The joint Cold Spring Harbor/Wellcome Trust Conference on pharmacogenomics, held in the USA and the UK in alternate years, focuses on the growing contribution of genomic technologies to the study of variable human responses to therapeutic agents. The meeting brings together researchers from academic, medical, regulatory and industrial sectors who discuss the current issues for the clinical implementation of pharmacogenomics, and to offer a look into the future advancements of technologies and the biostatistic and bioinformatic methodologies used to analyze arising complexity.

The IL1RN promoter rs4251961 correlates with IL-1 receptor antagonist concentrations in human infection and is differentially regulated by GATA-1

IL-1R antagonist (IL-1Ra) is required for adequate host defense in invasive pneumococcal disease (IPD). The minor allele of an IL1RN gene (C/T) promoter polymorphism (rs4251961) has been shown to be associated with decreased IL-1Ra production in healthy adults. We genotyped 299 children with IPD, and examined 19 IL1RN haplotype-tagging single-nucleotide polymorphisms. Human embryonic kidney HEK293(T) cells were transfected with the promoter reporter plasmid pGL3p containing either allelic variant C (pGL3pCC) or T (pGL3pTT) with or without cotransfection with an expression construct overexpressing the globin transcription factor GATA-1. Plasma IL-1Ra concentrations were significantly higher in nonsurvivors compared with survivors (p < 0.0005), and the C allele of rs4251961 was associated with a significant increase in plasma IL-1Ra concentrations (p = 0.01) during the acute illness of IPD. These findings were validated in a cohort of 276 treatment-naive HIV-infected adults, with borderline significance (p = 0.058). Functional analyses demonstrated that the activity of the promoter constructs containing the T allele increased ~6-fold as compared with basal activity, and that containing the C allele by ~9-fold (p < 0.001) in the presence of GATA-1. Our findings suggest that the IL-1Ra single-nucleotide polymorphism rs4251961 plays a key role in the pathophysiology of IPD and in other human infections.

Haplotype structure of CYP2B6 and association with plasma efavirenz concentrations in a Chilean HIV cohort

OBJECTIVES

Efavirenz is extensively metabolized by CYP2B6, and associations between CYP2B6 polymorphisms and plasma efavirenz exposure have been reported. The objective of this study was to investigate CYP2B6 haplotype structure and functional consequences in a Latin American population.

PATIENTS AND METHODS

Two hundred and nineteen patients were recruited at Fundación Arriarán, Chile, between September and December 2008. Plasma efavirenz concentrations were determined using liquid chromatography with mass spectrometry. Genotyping for 30 single nucleotide polymorphisms (SNPs) with a minor allele frequency of >0.05 in the HapMap CEU population at intervals of approximately 1 kb across the CYP2B6 locus was conducted using Sequenom iPLEX MALDI-TOF.

RESULTS

Thirteen SNPs passed quality control and, of these, statistically significant associations (P < 0.001) with plasma efavirenz concentrations were observed for 11. Pairwise tagging SNP analysis (R(2) > 0.8) identified 3 SNPs (rs10403955, rs2279345 and rs8192719) representative of the 11 associated SNPs. A composite genetic model of these three alleles was constructed, and an association between carriers of four to six of these alleles and the risk of efavirenz plasma concentrations >4 microg/mL was identified with an odds ratio of 48.1 (95% confidence interval: 13.5-207.7). This represents a positive predictive value of 80.9% and a negative predictive value of 91.8%, with sensitivity of 57.9% and specificity of 97.2%.

CONCLUSIONS

A composite genetic model of CYP2B6 SNPs in a Chilean HIV-positive cohort may have value in predicting concentrations of efavirenz associated with a higher likelihood of CNS toxicity. Further investigation of the functional basis of these associations is now required.

Investigation of inter-individual variability of the one-carbon folate pathway: a bioinformatic and genetic review

Genetic polymorphisms in the one-carbon folate pathway have been widely studied in association with a number of conditions. Most of the research has focused on the 677C>T polymorphism in the coding region of the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene. However, there are a total of 25 genes in this pathway coding for enzymes, transporters and receptors, which can be investigated using 267 tagging single nucleotide polymorphisms (SNPs); using SNP database (dbSNP), 38 non-synonymous SNPs with a minor allele frequency of >5% are present in these genes. Most of these variants have not been investigated in relation to disease or drug response phenotypes. In addition, their functional consequences are largely unknown. Prediction of the functional effect using six publicly available programs (PolyPhen, SIFT BLink, PMut, SNPs3D, I-Mutant2.0 and LS-SNP) was limited to functionally well-characterized SNPs such as MTHFR c.677C>T and c.1298A>C ranking low. Epigenetic modifications may also be important with some of these genes. In summary, to date, investigation of the one-carbon folate pathway genes has been limited. Future studies should aim for a more comprehensive assessment of this pathway, while further research is also required in determining the functional effects of these genetic variants.