HLA-B*5801 allele as a genetic marker for severe cutaneous adverse reactions caused by allopurinol

Drug hypersensitivity reactions: review of the state of the science for prediction and diagnosis

Drug hypersensitivity reactions (DHRs) are a type of adverse drug reaction that can occur with different classes of drugs and affect multiple organ systems and patient populations. DHRs can be classified as allergic or non-allergic based on the cellular mechanisms involved. Whereas nonallergic reactions rely mainly on the innate immune system, allergic reactions involve the generation of an adaptive immune response. Consequently, drug allergies are DHRs for which an immunological mechanism, with antibody and/or T cell, is demonstrated. Despite decades of research, methods to predict the potential for a new chemical entity to cause DHRs or to correctly attribute DHRs to a specific mechanism and a specific molecule are not well-established. This review will focus on allergic reactions induced by systemically administered low-molecular weight drugs with an emphasis on drug- and patient-specific factors that could influence the development of DHRs. Strategies for predicting and diagnosing DHRs, including potential tools based on the current state of the science, will also be discussed.

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

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

The association between HLA-B variants and amoxicillin-induced severe cutaneous adverse reactions in Chinese han population

Background

Amoxicillin (AMX) is among the most prescribed and the best tolerated antimicrobials worldwide. However, it can occasionally trigger severe cutaneous adverse reactions (SCAR) with a significant morbidity and mortality. The genetic factors that may be relevant to AMX-induced SCAR (AMX-SCAR) remain unclear. Identification of the genetic risk factor may prevent patients from the risk of AMX exposure and resume therapy with other falsely implicated drugs.

Methodology

Four patients with AMX-SCAR, 1,000 population control and 100 AMX-tolerant individuals were enrolled in this study. Both exome-wide and HLA-based association studies were conducted. Molecular docking analysis was employed to simulate the interactions between AMX and risk HLA proteins.

Results

Compared with AMX-tolerant controls, a significant association of HLA-B*15:01 with AMX-SCAR was validated [odds ratio (OR) = 22.9, 95% confidence interval (CI): 1.68-1275.67; p = 7.34 × 10-3]. Moreover, 75% carriers of HLA-B*15:01 in four patients with AMX-SCAR, and the carrier frequency of 10.7% in 1,000 control individuals and 11.0% in 100 AMX-tolerant controls, respectively. Within HLA-B protein, the S140 present in all cases and demonstrated the strongest association with AMX-SCAR [OR = 53.5, p = 5.18 × 10-4]. Molecular docking results also confirmed the interaction between AMX and S140 of the HLA-B protein, thus eliminating the false-positive results during in association analysis.

Conclusion

Our findings suggest that genetic susceptibility may be involved in the development of AMX-SCAR in Han Chinese. However, whether the HLA-B variants observed in this study can be used as an effective genetic marker of AMX-induced SCAR still needs to be further explored in larger cohort studies and other ethnic populations.

Phenomic landscape and pharmacogenomic implications for HLA region in a Taiwan Han Chinese population

BACKGROUND

The human leukocyte antigen (HLA) genes, exhibiting significant genetic diversity, are associated with susceptibility to various clinical diseases and diverse in drug responses. High costs of HLA sequencing and the population-specific architecture of this genetic region necessitate the establishment of a population-specific HLA imputation reference panel. Moreover, there is a lack of understanding about the genetic and phenotypic landscape of HLA variations within the Taiwanese population.

METHODS

We created models for a Taiwanese-specific HLA imputation reference panel. These models were trained with the array genotype data and HLA sequencing data from 845 Taiwanese subjects. HLA imputation was applied for 59,448 Taiwanese subjects to characterize the HLA allele and haplotype frequencies. Additionally, a phenome-wide association study (PheWAS) was conducted to identify the phenotypes associated with HLA variations. The association of the biallelic HLA variants with the binary and quantitative traits were evaluated with additive logistic and linear regression models, respectively. Furthermore, an omnibus test with likelihood-ratio test was applied for each HLA amino acid position in the multiallelic HLA amino acid polymorphisms to compare the difference between a fitted model and a null model following a χ2 distribution of n-1 degree of freedom at a position with n residues. Finally, we estimated the prevalence of adverse drug reactions (ADR)-related HLA alleles in the Taiwanese population.

RESULTS

In this study, the reference panel models displayed remarkable accuracy, with averages of 99.3%, 98.9%, and 99.1% for 2-, 4-, 6-digit alleles of the eight classical HLA genes, respectively. For PheWAS, a total of 18,136 significant associations with HLA variants across 26 phenotypes are identified (p < 5×10-8), highlighting the pleiotropy feature of the HLA region. Among the independent signals, 15 are novel, including the association of HLA-B pos 138 variation with ankylosing spondylitis (AS), and rs9266290 and rs9266292 with allergy. Through an analysis spanning the entire HLA region, we identified clusters of phenotype correlations. Finally, the carriers of pharmacogenomic related HLA alleles, including HLA-C*01:02 (35.86%), HLA-B*58:01 (20.9%), and HLA-B*15:02 (8.38%), were characterized in the Taiwanese general population.

CONCLUSIONS

We successfully delivered the HLA imputation for 59,448 Taiwanese subjects and characterized the genetic and phenotypic landscapes of the HLA variations. In addition, we quantified the estimated prevalence of the ADR-related HLA alleles in the Taiwanese population. The developed HLA imputation reference panel could be used for estimation of population HLA allele frequencies, which can facilitate further studies in the role of HLA variants in a wider range of phenotypes in the population.

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.

Influence of pharmacogenomic polymorphisms on allopurinol-induced cutaneous adverse drug reactions in Thai patients

BACKGROUND

Allopurinol has been causing substantial morbidity and mortality particularly in Asian population by producing cutaneous adverse drug reactions (cADRs). Nonetheless, there are no data describing whether other genetics are a valid marker for prediction of allopurinol-induced cADRs patients in addition to HLA-B*58:01 allele. The goal of this study was to identify suitable single nucleotide polymorphisms (SNPs) for allopurinol induced cADRs among Thai patients.

METHODS

We conducted a case-control association study after enrolling 57 Thai patients with allopurinol induced cADRs and 101 allopurinol-tolerant controls. The genetic biomarkers and associated SNPs located on chromosome 6p21 were examined by TaqMan® SNP genotyping assays in both the cases and the controls.

RESULTS

Out of fifteen SNPs in nine genes, we found four combined SNPs (rs3099844 of HCP5, rs9263726 of PSORS1C1, rs9263733 of POLR2LP, and rs9263745 of CCHCR1) were significantly associated with allopurinol-induced cADRs compared to the tolerant controls (OR 73.2; 95% CI 24.2-266.8; P = 1.9 × 10- 24). The overall sensitivity, specificity, positive predictive value and negative predictive value of these combinations were 84%, 94%, 9%, and 100%, respectively. However, the variant alleles of these SNP combinations were detected in 89.5% (51/57) of the cases. Moreover, the HLA-B*58:01 allele was observed in 86.0% of patients with allopurinol-induced cADRs, but only in 4.0% of tolerant controls (OR: 137.2; 95% CI: 38.3-670.5 and p-value = 1.7 × 10- 27).

CONCLUSIONS

Thus, this research confirms the association between the specific HLA-B*58:01 allele and all phenotypes of allopurinol-induced cADRs in Thais. Furthermore, there was found the combined four SNPs (rs3099844, rs9263726, rs9263733, and rs9263745) could be used as alternative novel biomarkers for predicting cADRs in patients taking allopurinol.

Clinical characteristics and genetic HLA marker for patients with oxaliplatin-induced adverse drug reactions

BACKGROUND

Oxaliplatin is commonly used to treat gastrointestinal malignancies. However, its applications are limited due to potential adverse drug reactions (ADRs), particularly severe anaphylactic shock. There is no method to predict or prevent ADRs caused by oxaliplatin. Therefore, we aimed to investigate the genetic HLA predisposition and immune mechanism of oxaliplatin-induced ADRs.

METHODS

A retrospective review was performed for 154 patients with ADRs induced by oxaliplatin during 2016-2021 recorded in our ADR notification system. HLA genotyping was conducted for 47 patients with oxaliplatin-induced ADRs, 1100 general population controls, and 34 oxaliplatin-tolerant controls in 2019-2023. The in vitro basophil activation test (BAT) was performed and oxaliplatin-specific IgE levels were determined.

RESULTS

The incidence of oxaliplatin-induced ADRs and anaphylactic shock in our cohort was 7.1% and 0.15%, respectively. Of the 154 patients, 67.5% suffered rash/eruption; 26.0% of the patients who could not undergo oxaliplatin rechallenge were considered to show oxaliplatin-induced immune-mediated hypersensitivity reactions (HRs). The genetic study found that the HLA-DRB∗12:01 allele was associated with oxaliplatin-induced HRs compared to the general population controls (sensitivity = 42.9%; odds ratio [OR] = 3.4; 95% CI = 1.4-8.2; P = 0.008) and tolerant controls (OR = 12; 95% CI = 2.3-63.7; P = 0.001). The in vitro BAT showed higher activation of CD63+ basophils in patients with oxaliplatin-induced HRs compared to the tolerant controls (P < 0.05). Only four patients (8.5%) with oxaliplatin-induced ADRs were positive for oxaliplatin-specific IgE.

CONCLUSIONS

This study found that 26.0% of patients with oxaliplatin-induced ADRs could not undergo oxaliplatin rechallenge. HLA-DRB∗12:01 is regarded as a genetic marker for oxaliplatin-induced hypersensitivity.

HLA-B*57:01-dependent intracellular stress in keratinocytes triggers dermal hypersensitivity reactions to abacavir

Specific human leukocyte antigen (HLA) polymorphisms combined with certain drug administration strongly correlate with skin eruption. Abacavir hypersensitivity (AHS), which is strongly associated with HLA-B*57:01, is one of the most representative examples. Conventionally, HLA transmits immunological signals via interactions with T cell receptors on the cell surface. This study focused on HLA-mediated intracellular reactions in keratinocytes that might determine the onset of skin immunotoxicity by drug treatments. Abacavir exposure resulted in keratinocytes expressing HLA-B*57:01 exhibiting endoplasmic reticulum (ER) stress responses, such as immediate calcium release into the cytosol and enhanced HSP70 expression. In contrast, keratinocytes expressing HLA-B*57:03 (closely related to HLA-B*57:01) did not show these changes. This indicated that HLA-B*57:01 has a specific intracellular response to abacavir in keratinocytes in the absence of lymphocytes. Furthermore, abacavir exposure in HLA-B*57:01-expressing keratinocytes elevated the expression of cytokines/chemokines such as interferon-γ, interleukin-1β, and CCL27, and induced T lymphoblast migration. These effects were suppressed by ER stress relief using 4-phenylbutyrate (4-PB). HLA-B*57:01-transgenic mice also exhibited ER stress in epidermal areas following abacavir administration, and abacavir-induced skin toxicity was attenuated by the administration of 4-PB. Moreover, abacavir bound to HLA-B*57:01 within cells and its exposure led to HLA-B*57:01 protein aggregation and interaction with molecular chaperones in the ER of keratinocytes. Our results underscore the importance of HLA-mediated intracellular stress responses in understanding the onset of HLA-B*57:01-mediated AHS. We provide the possibility that the intracellular behavior of HLA is crucial for determining the onset of drug eruptions.

Frequencies of HLA-B alleles in Indonesian Malay Ethnic

Background

The HLA-B alleles have been used as a marker to predict drug-induced adverse reactions and as a major contributor to hypersensitivity reactions. We examined the feasibility of HLA-B alleles as pharmacogenomic markers of drug-induced hypersensitivity in an Indonesian Malay Ethnic.

Methods

Fifty-eight Indonesian individuals of Malay ethnicity were enrolled in this study. HLA-B alleles were determined using reverse sequence-specific oligonucleotide probe coupled with xMAP technology.

Results

HLA-B*15:02 (15.52%), HLA-B*35:05 (9.48%), and HLA-B*07:05 (7.76%) were frequent alleles in the Indonesian Malay ethnic populations. We discovered at least eight pharmacogenomics markers of drug-induced hypersensitivity: HLA-B*15:02, HLA-B*15:21, HLA-B*13:01, HLA-B*35:05, HLA-B*38:02, HLA-B*51:01, HLA-B*57:01, and HLA-B*58:01. HLA-B*15:02 was in the same serotype group with HLA-B*15:21, which is a B-75 serotype associated with genetic predisposition for carbamazepine-induced Stevens-Johnson syndrome and toxic epidermal necrolysis. The Indonesian population, represented by Malay, Javanese, and Sundanese ethnicities, was similar to South East Asian, Han Chinese, and Taiwanese populations based on HLA-B*15:02 frequency as the most common allele found in Malay ethnics.

Conclusion

We provided valuable information on the frequency of drug hypersensitivity-associated HLA-B alleles in Indonesian Malay ethnic population, which can improve treatment safety.

Cutaneous adverse drug reactions

Cutaneous adverse drug reactions (ADRs) represent a heterogeneous field including various clinical patterns without specific features suggesting drug causality. Maculopapular exanthema and urticaria are the most common types of cutaneous ADR. Serious cutaneous ADRs, which may cause permanent sequelae or have fatal outcome, may represent 2% of all cutaneous ADR and must be quickly identified to guide their management. These serious reactions include bullous manifestations (epidermal necrolysis i.e. Stevens-Johnson syndrome and toxic epidermal necrolysis), drug reaction with eosinophilia and systemic symptoms (DRESS) and acute generalized exanthematous pustulosis (AGEP). Some risk factors for developing cutaneous ADRs have been identified, including immunosuppression, autoimmunity or genetic variants. All drugs can cause cutaneous ADRs, the most commonly implicated being antibiotics (especially aminopenicillins and sulfonamides), anticonvulsants, allopurinol, antineoplastic drugs, non-steroidal anti-inflammatory drugs and iodinated contrast media. Pathophysiology is related to immediate or delayed "idiosyncratic" immunologic mechanisms, i.e., usually not related to dose, and pharmacologic/toxic mechanisms, commonly dose-dependent and/or time-dependent. If an immuno-allergic mechanism is suspected, allergological explorations (including epicutaneous patch testing and/or intradermal test) are often possible to clarify drug causality, however these have a variable sensitivity according to the drug and to the ADR type. No in vivo or in vitro test can consistently confirm the drug causality. To determine the origin of a rash, a logical approach based on clinical characteristics, chronologic factors and elimination of differential diagnosis (especially infectious etiologies) is required, completed with a literature search. Reporting to pharmacovigilance system is therefore essential both to analyze drug causality at individual level, and to contribute to knowledge of the drug at population level, especially for serious cutaneous ADRs or in cases involving newly marketed drugs.

DRESS Syndrome: Renal Involvement in Two Cases - A Comprehensive Analysis and Literature Review of Improved Diagnosis and Treatment

BACKGROUND Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a rare hypersensitivity reaction involving the skin and various visceral organs; the kidneys are the second most affected organ. Many drugs are reported to be associated with DRESS, particularly antiepileptic agents and allopurinol. Certain human leukocyte antigen (HLA) haplotypes, in combination with a particular drug, can further contribute to an increased risk of DRESS. Symptoms often develop 2 to 8 weeks after drug initiation. If diagnosis is delayed, DRESS can be a life-threatening condition. CASE REPORT We present cases of 2 patients. The first patient was an 86-year-old Polish woman who developed acute kidney injury and skin lesions with accompanying leucocytosis and eosinophilia during long-term antibiotic therapy with piperacillin/tazobactam and ciprofloxacin. The second patient was a 37-year-old Asian woman with predialysis chronic renal disease stage V in the course of IgA nephropathy. Two weeks after starting allopurinol in a standard dose, she presented with maculopapular rash, facial edema, fever, liver injury, and eosinophilia. Renal function started to deteriorate, but she did not require dialysis. In both cases, the discontinuation of the above-mentioned drugs and the introduction of steroid therapy and intravenous immunoglobulins allowed for clinical improvement and recovery. In the second case, the extended 4-locus HLA typing was performed retrospectively, and allele HLA-B*5801 was found. CONCLUSIONS Due to the rare occurrence and heterogeneous manifestation of DRESS, its diagnosis can pose many difficulties. In-depth analysis of symptoms, medicines taken, and laboratory findings enable the implementation of appropriate treatment and recovery.

Implementing HLA-B*58:01 testing prior to allopurinol initiation in Malaysian primary care setting: A qualitative study from doctors' and patients' perspective

INTRODUCTION

Allopurinol, the first-line treatment for chronic gout, is a common causative drug for severe cutaneous adverse reactions (SCAR). HLA-B*58:01 allele was strongly associated with allopurinol-induced SCAR in Asian countries such as Taiwan, Japan, Thailand and Malaysia. HLA-B*58:01 screening before allopurinol initiation is conditionally recommended in the Southeast-Asian population, but the uptake of this screening is slow in primary care settings, including Malaysia. This study aimed to explore the views and experiences of primary care doctors and patients with gout on implementing HLA-B*58:01 testing in Malaysia as part of a more extensive study exploring the feasibility of implementing it routinely.

METHODS

This qualitative study used in-depth interviews and focus group discussions to obtain information from patients with gout under follow-up in primary care and doctors who cared for them. Patients and doctors shared their gout management experiences and views on implementing HLA-B*58:01 screening in primary care. Data were coded and analysed using thematic analysis.

RESULTS

18 patients and 18 doctors from three different healthcare settings (university hospital, public health clinics, private general practitioner clinics) participated. The acceptability to HLA-B*58:01 screening was good among the doctors and patients. We discovered inadequate disclosure of severe side effects of allopurinol by doctors due to concerns about medication refusal by patients, which could potentially be improved by introducing HLA-B*58:01 testing. Barriers to implementation included out-of-pocket costs for patients, the cost-effectiveness of this implementation, lack of established alternative treatment pathway besides allopurinol, counselling burden and concern about genetic data security. Our participants preferred targeted screening for high-risk populations instead of universal screening.

CONCLUSION

Implementing HLA-B*58:01 testing in primary care is potentially feasible if a cost-effective, targeted screening policy on high-risk groups can be developed. A clear treatment pathway for patients who test positive should be made available.

The expanding role of HLA gene tests for predicting drug side effects

Adverse drug reactions can be either dose-dependent (Type A) or idiosyncratic (Type B). Type B adverse drug reactions tend to be extremely rare and difficult to predict. They are usually immune-mediated. Examples include severe skin reactions and drug-induced liver injury. For many commonly prescribed drugs (such as antibiotics), the risk of developing an idiosyncratic adverse drug reaction is influenced by variability in the human leukocyte antigen (HLA) genes. Because these HLA-mediated adverse drug reactions can be lethal, there is growing interest in defining which specific drug-gene relationships might benefit from pre-emptive HLA genotyping and automated clinical decision support. This review summarizes the literature for HLA-mediated adverse reactions linked to common drugs.

Osimertinib-induced Keratitis and Secondary Toxic Epidermal Necrotic Drug Eruption- A Case Report and Literature Review

BACKGROUND

Osimertinib is a third-generation Tyrosine Kinase inhibitor, mainly used in non-small cell lung cancer with EGFR mutation. Its efficacy and safety have been confirmed by clinical practice. Toxic epidermolysis necrotizing disease (TEN) is a severe drug eruption that is rare in clinics and has a high mortality rate. Toxic epidermal necrotic drug rash caused by Osimeritinib is even rarer.

OBJECTIVE

To investigate the rare side effects of Osimertinib through a case of toxic Epidermal necrosis.

CASE PRESENTATION

A 63-year-old female patient was diagnosed with lung adenocarcinoma with brain metastases, and genetic testing revealed an EGFR21 exon mutation. The disease progressed 24 days after the administration of gefitinib, then the patient switched to Osimertinib (80 mg QD) and, resulting in keratitis and secondary systemic toxic epidermolysis necrotizing disease (TEN). Finally, the patient died.

CONCLUSION

Although the clinical use of osimertinib is becoming widespread, the side effects may not be fully understood. Clinicians should pay more attention to the occurrence of the side reaction and deal with it in time.

Clinical variables and genetic variants associated with perioperative anaphylaxis in Chinese Han population: A pilot study

Background

Perioperative anaphylaxis (POA) can lead to severe consequences. Identifying clinical risk factors and genetic loci associated with POA through pre-prescription screening may help reduce its incidence.

Methods

Using univariate regression and covariate-adjusted multivariate regression, we retrospectively analyzed the association between clinical characteristics and POA in 72 POA patients and 72 non-POA individuals. The discovery study of whole-exome association relied on whole-exome sequencing of 73 POA cases and 1339 healthy individuals. A replication study involving an independent set of 16 POA cases and 1339 healthy individuals confirmed this association. The accurate typing of human leucocyte antigen through exome sequencing (ATHLATES) algorithm and the whole-exome sequencing data were used for genotyping the human leucocyte antigen G (HLA-G) of 73 POA patients. The HLA-G of 16 POA cases and 122 non-POA patients were genotyped through Sanger sequencing. We used Fisher's exact probability method to compare the allele and carrier frequencies between POA patients and healthy individuals or non-POA patients. A Pc (P/Bonferroni correction coefficient) < 0.05 represents statistical significance.

Results

Regression analysis identified female sex, an unconfirmed food allergy label, and a history of prior surgery as clinical variables associated with POA. The whole-exome association discovery study identified a strong signal in the major histocompatibility complex region on chromosome 6, with the rs1130356 being the most significant locus (P = 1.5E-10, OR = 3.4, 95% CI = 2.4-4.9). The replication study verified the association between the rs1130356-T allele and POA cases (P = 1.0E-6, OR = 6.3, 95% CI = 3.1-12.7). Compared with non-POA patients, HLA-G∗01:01 (Pc = 2.4E-4, OR = 2.4, 95% CI = 1.6-3.6) was significantly enriched, while HLA-G∗01:04 (Pc = 1.2E-6, OR = 0.3, 95% CI = 0.2-0.5) was lessened in POA patients.

Conclusion

Our study suggested an association between POA and the risk factors of female sex, an unconfirmed food allergy label, and prior surgery. HLA-G, located in the human leucocyte antigen (HLA) region, may act as a surrogate genetic marker for POA. This suggests a causal relationship between this specific genomic region and POA. Our findings shed light on the contribution of human exome genetic variants to the susceptibility to POA.

Comparison of Class-Specific Side Effects Across Preventative Pharmacologic Therapies for Kidney Stone Disease

INTRODUCTION

Clinical guidelines recommend monitoring for metabolic derangements while on preventive pharmacologic therapy for kidney stone disease. The study objective was to compare the frequency of side effects among patients receiving alkali citrate, thiazides, and allopurinol.

METHODS

Using claims data from working-age adults with kidney stone disease (2008-2019), we identified those with a new prescription for alkali citrate, thiazide, or allopurinol within 12 months after their index stone-related diagnosis or procedure. We fit multivariable logistic regression models, adjusting for cohort characteristics like comorbid illness and medication adherence, to estimate 2-year measured frequencies of claims-based outcomes of acute kidney injury, falls/hip fracture, gastritis, abnormal liver function tests/hepatitis, hypercalcemia, hyperglycemia/diabetes, hyperkalemia, hypokalemia, hyponatremia, and hypotension.

RESULTS

Our cohort consisted of 1776 (34%), 2767 (53%), and 677 (13%) patients prescribed alkali citrate, thiazides, or allopurinol, respectively. Comparing unadjusted rates of incident diagnoses, thiazides compared to alkali citrate and allopurinol were associated with the highest rates of hypercalcemia (2.3% vs 1.5% and 1.0%, respectively, P = .04), hypokalemia (6% vs 3% and 2%, respectively, P < .01), and hyperglycemia/diabetes (17% vs 11% and 16%, respectively, P < .01). No other differences with the other outcomes were significant. In adjusted analyses, compared to alkali citrate, thiazides were associated with a higher odds of hypokalemia (OR=2.01, 95% CI 1.44-2.81) and hyperglycemia/diabetes (OR=1.52, 95% CI 1.26-1.83), while allopurinol was associated with a higher odds of hyperglycemia/diabetes (OR=1.34, 95% CI 1.02-1.75).

CONCLUSIONS

These data provide evidence to support clinical guidelines that recommend periodic serum testing to assess for adverse effects from preventive pharmacologic therapy.

Elucidating the Mechanisms Underlying Interindividual Differences in the Onset of Adverse Drug Reactions

Idiosyncratic drug toxicities (IDTs) pose a significant challenge; they are marked by life-threatening adverse reactions that emerge aftermarket release and are influenced by intricate genetic and environmental variations. Recent genome-wide association studies have highlighted a strong correlation between specific human leukocyte antigen (HLA) polymorphisms and IDT onset. This review provides an overview of current research on HLA-mediated drug toxicities. In the last six years, HLA-transgenic (Tg) mice have been instrumental in advancing our understanding of these underlying mechanisms, uncovering systemic immune reactions that replicate human drug-induced immune stimulation. Additionally, the potential role of immune tolerance in shaping individual differences in adverse effects highlights its relevance to the interplay between HLA polymorphisms and IDTs. Although HLA-Tg mice offer valuable insights into systemic immune reactions, further exploration is essential to decipher the intricate interactions that lead to organ-specific adverse effects, especially in organs such as the skin or liver. Navigating the intricate interplay of HLA, which may potentially trigger intracellular immune responses, this review emphasizes the need for a holistic approach that integrates findings from both animal models and molecular/cellular investigations. The overarching goal is to enhance our comprehensive understanding of HLA-mediated IDTs and identify factors shaping individual variations in drug reactions. This review aims to facilitate the development of strategies to prevent severe adverse effects, address existing knowledge gaps, and provide guidance for future research initiatives in the field of HLA-mediated IDTs.

Genetic Susceptibility of HLA Alleles to Non-Steroidal Anti-Inflammatory Drug Hypersensitivity in the Taiwanese Population

BACKGROUND

Human leukocyte antigen (HLA) genes are important in many immune processes and contribute to many adverse drug reactions. Whether genetic variations in the HLA region are associated with non-steroid anti-inflammatory drug (NSAID) hypersensitivity remains uncertain. Therefore, the aim of our study was to identify HLA genetic variations in patients with NSAID hypersensitivity in the Taiwanese population.

METHODS

This hospital-based, retrospective case-control study enrolled 37,156 participants with NSAID exposure from the Taiwan Precision Medicine Initiative (TPMI), who were all genotyped and imputed to fine map HLA typing. Our study assigned 1217 cases to the NSAID allergy group and 12,170 controls to a matched group. Logistic regression analyses were utilized to explore associations between HLA alleles and NSAID hypersensitivity.

RESULTS

Overall, 13,387 patients were genotyped for eight major HLA alleles. Allele frequencies were different between the two groups. In the NSAID allergy group, the genotype frequencies of HLA-A*02:01, HLA-A*34:01, and HLA-DQA1*06:01 were found to be markedly elevated compared to the control group, a significance that persisted even after applying the Bonferroni correction. Furthermore, the risk of NSAID allergy demonstrated a significant association with HLA-A*02:01 (OR = 1.29, p < 0.001) and HLA-A*34:01 (OR = 9.90, p = 0.001), in comparison to their respective counterparts. Notably, the genotype frequency of HLA-B*46:01 exhibited a significant increase in the severe allergy group when compared with the mild allergy group.

CONCLUSIONS

We identified HLA genotypes linked to the onset and severity of NSAID hypersensitivity. Our findings establish a basis for precision prescription in future clinical applications.

Impact of Pharmacogenomics in Clinical Practice

Polymorphisms of genes encoding drug metabolizing enzymes and transporters can significantly modify pharmacokinetics, and this can be associated with significant differences in drug efficacy, safety, and tolerability. Moreover, genetic variants of some components of the immune system can explain clinically relevant drug-related adverse events. However, the implementation of drug dose individualization based on pharmacogenomics remains scarce. In this narrative review, the impact of genetic variations on the disposition, safety, and tolerability of the most commonly prescribed drugs is reported. Moreover, reasons for poor implementation of pharmacogenomics in everyday clinical settings are discussed. The literature analysis showed that knowledge of how genetic variations can modify the effectiveness, safety, and tolerability of a drug can lead to the adjustment of usually recommended drug dosages, improve effectiveness, and reduce drug-related adverse events. Despite some efforts to introduce pharmacogenomics in clinical practice, presently very few centers routinely use genetic tests as a guide for drug prescription. The education of health care professionals seems critical to keep pace with the rapidly evolving field of pharmacogenomics. Moreover, multimodal algorithms that incorporate both clinical and genetic factors in drug prescribing could significantly help in this regard. Obviously, further studies which definitively establish which genetic variations play a role in conditioning drug effectiveness and safety are needed. Many problems must be solved, but the advantages for human health fully justify all the efforts.

The allopurinol metabolite, oxypurinol, drives oligoclonal expansions of drug-reactive T cells in resolved hypersensitivity cases and drug-naïve healthy donors

Allopurinol (ALP) is a successful drug used in the treatment of gout. However, this drug has been implicated in hypersensitivity reactions that can cause severe to life-threatening reactions such as Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Individuals who carry the human leukocyte antigen (HLA)-B*58:01 allotype are at higher risk of experiencing a hypersensitivity reaction (odds ratios ranging from 5.62 to 580.3 for mild to severe reactions, respectively). In addition to the parent drug, the metabolite oxypurinol (OXP) is implicated in triggering T cell-mediated immunopathology via a labile interaction with HLA-B*58:01. To date, there has been limited information regarding the T-cell receptor (TCR) repertoire usage of reactive T cells in patients with ALP-induced SJS or TEN and, in particular, there are no reports examining paired αβTCRs. Here, using in vitro drug-treated PBMCs isolated from both resolved ALP-induced SJS/TEN cases and drug-naïve healthy donors, we show that OXP is the driver of CD8+ T cell-mediated responses and that drug-exposed memory T cells can exhibit a proinflammatory immunophenotype similar to T cells described during active disease. Furthermore, this response supported the pharmacological interaction with immune receptors (p-i) concept by showcasing (i) the labile metabolite interaction with peptide/HLA complexes, (ii) immunogenic complex formation at the cell surface, and (iii) lack of requirement for antigen processing to elicit drug-induced T cell responsiveness. Examination of paired OXP-induced αβTCR repertoires highlighted an oligoclonal and private clonotypic profile in both resolved ALP-induced SJS/TEN cases and drug-naïve healthy donors.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Structural analysis and attenuates hyperuricemic nephropathy of dextran from the Imperata cylindrica Beauv. var. major (Nees) C. E. Hubb

ICPC-a was from the Imperata cylindrica with a molecular weight of 45 kDa, which was composed of α-D-1,3-Glcp and α-D-1,6-Glcp. The ICPC-a showed thermal stability, maintaining its structural integrity up to 220°C. X-ray diffraction analysis confirmed its amorphous nature, while scanning electron microscopy revealed a layered morphology. ICPC-a significantly ameliorated uric acid stimulation-induced HK-2 cell injury and apoptosis and reduced uric acid levels in mice with hyperuricemic nephropathy. ICPC-a protected against renal injury by inhibiting lipid peroxidation levels, increasing antioxidant damage and defense levels, inhibiting secretion of pro-inflammatory factors, regulating purine metabolism, PI3K-Akt signaling pathway, NF-κB signaling pathway, inflammatory bowel disease, mTOR signaling pathway, and MAPK signaling pathway. These findings indicate that ICPC-a is a promising natural substance with multiple targets, multiple pathways of action, and without toxicity, making it a valuable subject for further research and development.

Population pharmacokinetics, pharmacodynamics and pharmacogenetics modelling of oxypurinol in Hmong adults with gout and/or hyperuricemia

AIMS

The aim of this study was to quantify identifiable sources of variability, including key pharmacogenetic variants in oxypurinol pharmacokinetics and their pharmacodynamic effect on serum urate (SU).

METHODS

Hmong participants (n = 34) received 100 mg allopurinol twice daily for 7 days followed by 150 mg allopurinol twice daily for 7 days. A sequential population pharmacokinetic pharmacodynamics (PKPD) analysis with non-linear mixed effects modelling was performed. Allopurinol maintenance dose to achieve target SU was simulated based on the final PKPD model.

RESULTS

A one-compartment model with first-order absorption and elimination best described the oxypurinol concentration-time data. Inhibition of SU by oxypurinol was described with a direct inhibitory Emax model using steady-state oxypurinol concentrations. Fat-free body mass, estimated creatinine clearance and SLC22A12 rs505802 genotype (0.32 per T allele, 95% CI 0.13, 0.55) were found to predict differences in oxypurinol clearance. Oxypurinol concentration required to inhibit 50% of xanthine dehydrogenase activity was affected by PDZK1 rs12129861 genotype (-0.27 per A allele, 95% CI -0.38, -0.13). Most individuals with both PDZK1 rs12129861 AA and SLC22A12 rs505802 CC genotypes achieve target SU (with at least 75% success rate) with allopurinol below the maximum dose, regardless of renal function and body mass. In contrast, individuals with both PDZK1 rs12129861 GG and SLC22A12 rs505802 TT genotypes would require more than the maximum dose, thus requiring selection of alternative medications.

CONCLUSIONS

The proposed allopurinol dosing guide uses individuals' fat-free mass, renal function and SLC22A12 rs505802 and PDZK1 rs12129861 genotypes to achieve target SU.

Cardiovascular Safety Evaluation of Febuxostat and Allopurinol: Findings from the FDA Adverse Event Reporting System

BACKGROUND

Febuxostat and allopurinol are the most commonly used uric acid-lowering medications, and their safety is of great concern, especially the cardiovascular adverse reactions associated with febuxostat. We propose to study the cardiovascular toxicity of febuxostat and allopurinol using the FDA Adverse Event Reporting System (FAERS) database.

METHODS

A total of 64 quarters of FAERS data were downloaded from 2004 to 2019. Febuxostat- and allopurinol-related cardiovascular adverse events were extracted after data cleaning. Signal detection was conducted by reporting odds ratio (ROR) and proportional reporting ratio (PRR).

RESULTS

There were 2939 and 25,219 reports of febuxostat- and allopurinol-related cardiovascular adverse events (CVAEs), respectively. The most frequent CVAEs with febuxostat and allopurinol were edema peripheral (14.38%) and peripheral swelling (8.76%), respectively. In elderly gout patients, febuxostat is associated with an increased risk of heart failure, ischemic heart disease, hypertension, and cardiomyopathy. Febuxostat in combination with acetic acid derivatives nonsteroidal anti-inflammatory drug (NSAIDS) also increases the risk of cardiovascular adverse events.

CONCLUSIONS

Compared with allopurinol, febuxostat may increase cardiovascular toxicity in patients with gout.

Association between HLA alleles and beta-lactam antibiotics-related severe cutaneous adverse reactions

Introduction: Beta-lactam antibiotics are one of the most common causes of antibiotics-related severe cutaneous adverse reactions (SCARs) including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reactions with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP). Recent evidence demonstrated that the human leukocyte antigen (HLA) polymorphisms play important roles in the development of drug-related SCARs. This study aimed to extensively characterize the associations between HLA genetic polymorphisms and several phenotypes of SCARs related to beta-lactam antibiotics. Methods: Thirty-one Thai patients with beta-lactam antibiotics-related SCARs were enrolled in the study. A total of 183 unrelated native Thai subjects without any evidence of drug allergy were recruited as the control group. Genotyping of HLA class I and class II alleles was performed. Results: Six HLA alleles including HLA-A*01:01, HLA-B*50:01, HLA-C*06:02, HLA-DRB1*15:01, HLA-DQA1*03:01, and HLA-DQB1*03:02, were significantly associated with beta-lactam antibiotics-related SCARs. The highest risk of SCARs was observed in patients with the HLA-B*50:01 allele (OR = 12.6, 95% CI = 1.1-142.9, p = 0.042), followed by the HLA-DQB1*03:02 allele (OR = 5.8, 95% CI = 1.5-22.0, p = 0.012) and the HLA-C*06:02 allele (OR = 5.7, 95% CI = 1.6-19.9, p = 0.011). According to the phenotypes of SCARs related to beta-lactam antibiotics, the higher risk of SJS/TEN was observed in patients with HLA-A*03:02, HLA-B*46:02 (OR = 17.5, 95% CI = 1.5-201.6, p = 0.033), HLA-A*02:06, HLA-B*57:01 (OR = 9.5, 95% CI = 1.3-71.5, p = 0.028), HLA-DQB1*03:02 (OR = 7.5, 95% CI = 1.8-30.9, p = 0.008), or HLA-C*06:02 (OR = 4.9, 95% CI = 1.1-21.4, p = 0.008). While eight HLA alleles including HLA-A*02:05, HLA-A*02:11, HLA-B*37:01, HLA-B*38:01, HLA-B*50:01, HLA-C*06:02, HLA-C*03:09, and HLA-DRB1*15:01 were associated with AGEP, the highest risk of AGEP was observed in patients with the HLA-B*50:01 allele (OR = 60.7, 95% CI = 4.8-765.00, p = 0.005). Among the four HLA alleles associated with DRESS including HLA-C*04:06, HLA-DRB1*04:05, HLA-DRB1*11:01, and HLA-DQB1*04:01, the HLA-C*04:06 allele had the highest risk of beta-lactam antibiotics-related DRESS (OR = 60.0, 95% CI = 3.0-1202.1, p = 0.043). However, these associations did not achieve statistical significance after Bonferroni's correction. Apart from the HLA risk alleles, the HLA-A*02:07 allele appeared to be a protective factor against beta-lactam antibiotic-related SCARs (OR = 0.1, 95% CI = 0.0-0.5, p = 3.7 × 10-4, Pc = 0.012). Conclusion: This study demonstrated the candidate HLA alleles that are significantly associated with several phenotypes of beta-lactam antibiotics-related SCARs. However, whether the HLA alleles observed in this study can be used as valid genetic markers for SCARs related to beta-lactam antibiotics needs to be further explored in other ethnicities and larger cohort studies.

An association study of HLA with levofloxacin-induced severe cutaneous adverse drug reactions in Han Chinese

Levofloxacin-induced severe cutaneous adverse drug reactions (LEV-SCARs) remain unexplored. An association study of human leukocyte antigen (HLA) alleles with LEV-SCARs among 12 patients, 806 healthy subjects, and 100 levofloxacin-tolerant individuals was performed. The carrier frequencies of HLA-B∗13:01 (odds ratio [OR]: 4.50; 95% confidence interval [CI]: 1.15-17.65; p = 0.043), HLA-B∗13:02 (OR: 6.14; 95% CI: 1.73-21.76; p = 0.0072), and serotype B13 (OR: 17.73; 95% CI: 3.61-86.95; p = 4.85 × 10-5) in patients with LEV-SCARs were significantly higher than those of levofloxacin-tolerant individuals. Molecular docking analysis suggested that levofloxacin formed more stable binding models with HLA-B∗13:01 and HLA-B∗13:02 than with non-risk HLA-B∗46:01. Mass spectrometry revealed that nonapeptides bound to HLA-B∗13:02 shifted at several positions after exposure to levofloxacin. Prospective screening for serotype B13 (sensitivity: 83%, specificity: 78%) and alternative drug treatment for carriers may significantly decrease the incidence of LEV-SCARs.

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.

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

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

Severe ocular complications of SJS/TEN and associations among pre-onset, acute, and chronic factors: a report from the international ophthalmology collaborative group

We formed an international research collaboration that included Japan, South Korea, Brazil, Thailand, Taiwan, the UK, and the US (682 patients from 13 hospitals between 2005 and 2020), to better evaluate the role of race, ethnicity, and other risk factors in the pathophysiology of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Ophthalmologists often see SJS/TEN patients with severe ocular complications (SOC; frequency 50% SJS/TEN patients) when the patients are referred to them in the chronic stage after the acute stage has passed. Global data were collected using a Clinical Report Form, capturing pre-onset factors, as well as acute and chronic ocular findings. Key conclusions of this retrospective observational cohort study were as follows: (1) Ingestion of cold medications [acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs)] was significantly and positively correlated with trichiasis, symblepharon, and/or conjunctivalization of the cornea in the chronic stage; (2) common cold symptoms prior to onset of SJS/TEN were significantly and positively correlated with acute conjunctivitis and ocular surface erosions in the acute stage and with trichiasis and symblepharon and/or conjunctivalization of the cornea in the chronic stage; (3) patients with SJS/TEN who presented with SOC tended to be female; (4) patients less than 30 years of age are more likely to develop SOC in the acute and chronic stages of SJS/TEN; (5) patients with acute severe conjunctivitis with ocular surface erosion and pseudomembrane formation in the acute stage are more likely to develop ocular sequelae in the chronic stage; and (6) onychopathy in the acute stage was positively correlated with ocular sequelae in the chronic stage. Our findings show that the ingestion of cold medications, common cold symptoms prior to the onset of SJS/TEN, and a young age might strongly contribute to developing the SOC of SJS/TEN.

Allopurinol non-covalently facilitates binding of unconventional peptides to HLA-B*58:01

Allopurinol, widely used in gout treatment, is the most common cause of severe cutaneous adverse drug reactions. The risk of developing such life-threatening reactions is increased particularly for HLA-B*58:01 positive individuals. However the mechanism of action between allopurinol and HLA remains unknown. We demonstrate here that a Lamin A/C peptide KAGQVVTI which is unable to bind HLA-B*58:01 on its own, is enabled to form a stable peptide-HLA complex only in the presence of allopurinol. Crystal structure analysis reveal that allopurinol non-covalently facilitated KAGQVVTI to adopt an unusual binding conformation, whereby the C-terminal isoleucine does not engage as a PΩ that typically fit deeply in the binding F-pocket. A similar observation, though to a lesser degree was seen with oxypurinol. Presentation of unconventional peptides by HLA-B*58:01 aided by allopurinol contributes to our fundamental understanding of drug-HLA interactions. The binding of peptides from endogenously available proteins such as self-protein lamin A/C and viral protein EBNA3B suggest that aberrant loading of unconventional peptides in the presence of allopurinol or oxypurinol may be able to trigger anti-self reactions that can lead to Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) and Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS).

Systemic Versus Topical Corticosteroids in the Treatment of DRESS: A Retrospective Cohort Study Followed by a Meta-Analysis

BACKGROUND

Drug reaction with eosinophilia and systemic symptoms (DRESS) is a severe systemic drug hypersensitivity syndrome with significant risks of mortality and long-term sequelae. Management is challenging; whilst systemic corticosteroids are generally regarded as standard of care, there is a suggestion that topical corticosteroids may be a safe alternative.

OBJECTIVE

We aimed to compare the clinical outcomes of patients with DRESS treated with systemic corticosteroids and topical corticosteroids in an academic medical center.

METHODS

The medical records of patients diagnosed with DRESS at the Singapore General Hospital between 2009 and 2017 were retrospectively reviewed. A secondary systematic review and meta-analysis were performed to further clarify the outcomes.

RESULTS

Out of 94 patients with DRESS, 41 (44%) were treated with topical corticosteroids and 53 (56%) were treated with systemic corticosteroids. Patients receiving systemic corticosteroids were more likely to develop infective complications (32.1 vs 12.2%, p = 0.02). One-month and 12-month mortality, length of hospital stay, flares of DRESS, and viral reactivation were similar between the two groups. In our meta-analysis (six studies, n = 292), there were no significant differences in mortality or length of stay between patients treated with systemic or topical corticosteroids.

LIMITATIONS

This study was a non-controlled retrospective cohort study and the allocation of treatment may have been influenced by the severity of disease. Results of the secondary meta-analysis are limited by the quality of included studies.

CONCLUSIONS

Topical corticosteroids may be a safe and efficacious alternative to systemic corticosteroids in the treatment of mild-to-moderate DRESS.

CLINICAL TRIAL REGISTRATION

PROSPERO registration CRD42021285691.

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

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

A consensual machine-learning-assisted QSAR model for effective bioactivity prediction of xanthine oxidase inhibitors using molecular fingerprints

Xanthine oxidase inhibitors (XOIs) have been widely studied due to the promising potential as safe and effective therapeutics in hyperuricemia and gout. Currently, available XOI molecules have been developed from different experiments but they are with the wide structure diversity and significant varying bioactivities. So it is of great practical significance to present a consensual QSAR model for effective bioactivity prediction of XOIs based on a systematic compiling of these XOIs across different experiments. In this work, 249 XOIs belonging to 16 scaffolds were collected and were integrated into a consensual dataset by introducing the concept of IC₅₀ values relative to allopurinol (RIC₅₀). Here, extended connectivity fingerprints (ECFPs) were employed to represent XOI molecules. By performing effective feature selection by machine-learning method, 54 crucial fingerprints were indicated to be valuable for predicting the inhibitory potency (IP) of XOIs. The optimal predictor yields the promising performance by different cross-validation tests. Besides, an external validation of 43 XOIs and a case study on febuxostat also provide satisfactory results, indicating the powerful generalization of our predictor. Here, the predictor was interpreted by shapely additive explanation (SHAP) method which revealed several important substructures by mapping the featured fingerprints to molecular structures. Then, 15 new molecules were designed and predicted by our predictor to show superior IP than febuxostat. Finally, molecular docking simulation was performed to gain a deep insight into molecular binding mode with xanthine oxidase (XO) enzyme, showing that molecules with selenazole moiety, cyano group and isopropyl group tended to yield higher IP. The absorption, distribution, metabolism, excretion and toxicity (ADMET) prediction results further enhanced the potential of these novel XOIs as drug candidates. Overall, this work presents a QSAR model for accurate prediction of IP of XOIs, and is expected to provide new insights for further structure-guided design of novel XOIs.

Validation of a genotyping technique for a surrogate marker of HLA-B∗58:01 for allopurinol-induced Stevens-Johnson syndrome and toxic epidermal necrolysis in the Japanese population

Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are rare but severe cutaneous adverse drug reactions. Certain human leukocyte antigen (HLA) types have been associated with SJS/TEN onset, e.g., HLA-B^∗58:01 with allopurinol-induced SJS/TEN, but HLA typing is time-consuming and expensive; thus, it is not commonly used in clinical situations. In the previous work, we demonstrated that the single-nucleotide polymorphisms (SNP) rs9263726 was in absolute linkage disequilibrium with HLA-B^∗58:01 in the Japanese population, and can be used as a surrogate marker for the HLA. Here, we developed a new genotyping method for the surrogate SNP using the single-stranded tag hybridization chromatographic printed-array strip (STH-PAS) technique and performed an analytical validation. The results of genotyping rs9263726 using STH-PAS correlated well with those obtained using the TaqMan SNP Genotyping Assay for 15 HLA-B^∗58:01-positive and 13 HLA-B^∗58:01-negative patients (analytical sensitivity and specificity were both 100%). Additionally, at least 1.11 ng of genomic DNA was sufficient to digitally and manually detect positive signals on the strip. Robustness studies showed that the annealing temperature (66 °C) was the most important condition related to reliable results. Collectively, we developed an STH-PAS method that can rapidly and easily detect rs9263726 for predicting SJS/TEN onset.

Effect of febuxostat on adverse events and mortality in gout in Taiwan: An interrupted time series analysis

OBJECTIVES

To evaluate the influence of febuxostat on adverse events and mortality in gout.

METHODS

We retrospectively enrolled patients with newly diagnosed gout and prescribed urate-lowering therapy between 2006 and 2017 from the Taiwan National Health Insurance Database. These patients were divided into 2 groups: with and without comorbidities (n = 294 847 and 194 539). An interrupted time series analysis with adjustments for demographics, comorbidities, and comedication by propensity score-based stabilized weights was used to compare the trend of adverse events and mortality before vs after febuxostat was introduced in 2012.

RESULTS

The proportion of febuxostat use gradually increased from 0% in 2012 to 30% in those with comorbidities and 10% in those without comorbidities in 2017. Allopurinol use decreased from 30% in 2012 to 10% in 2017. The slope of the 1-year incidence rate of Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN) (per 10 000 patients) significantly reduced after 2012 in those with and without comorbidities (-0.375 per quarter, P = .015 and -.253 per quarter, P = .049). The slope of the 3-year incidence rate of acute myocardial infarction (AMI) (per 1000 patients), percutaneous coronary intervention (PCI) (per 1000 patients), and all-cause mortality (per 100 patients) significantly increased after 2012 in those with comorbidities (+0.207 per quarter, P = .013; +.389 per quarter, P = .002; +.103 per quarter, P = .001).

CONCLUSIONS

Febuxostat may reduce SJS and TEN in all gout patients but increase AMI, PCI, and all-cause mortality in gout patients with comorbidities.

HIV-Associated Immune Dysregulation in the Skin: A Crucible for Exaggerated Inflammation and Hypersensitivity

Skin diseases are hallmarks of progressive HIV-related immunosuppression, with severe noninfectious inflammatory and hypersensitivity conditions as common as opportunistic infections. Conditions such as papular pruritic eruption are AIDS defining, whereas delayed immune-mediated adverse reactions, mostly cutaneous, occur up to 100-fold more during HIV infection. The skin, constantly in contact with the external environment, has a complex immunity. A dense, tightly junctioned barrier with basal keratinocytes and epidermal Langerhans cells with antimicrobial, innate-activating, and antigen-presenting functions form the frontline. Resident dermal dendritic, mast, macrophage, and innate lymphoid cells play pivotal roles in directing and polarizing appropriate adaptive immune responses and directing effector immune cell trafficking. Sustained viral replication leads to progressive declines in CD4 T cells, whereas Langerhans and dermal dendritic cells serve as viral reservoirs and points of first viral contact in the mucosa. Cutaneous cytokine responses and diminished lymphoid populations create a crucible for exaggerated inflammation and hypersensitivity. However, beyond histopathological description, these manifestations are poorly characterized. This review details normal skin immunology, changes associated with progressive HIV-related immunosuppression, and the characteristic conditions of immune dysregulation increased with HIV. We highlight the main research gaps and several novel tissue-directed strategies to define mechanisms that will provide targeted approaches to prevention or treatment.

DNA methylation of ITGB2 contributes to allopurinol hypersensitivity

BACKGROUNDS

HLA-B*58:01 allele was strongly associated with allopurinol induced severe cutaneous adverse drug reaction (SCAR). However, HLA-B genotype is not sufficient to predict the occurrence of allopurinol-induced SCAR.

OBJECTIVE

To discover DNA methylation markers for allopurinol-induced SCAR which may improve the prediction accuracy of genetic testing.

STUDY DESIGN

The study was designed as a retrospective case-control clinical study in multicenter hospitals across Taiwan, Mainland China, Malaysia and Canada. 125 cases of allopurinol-induced SCAR patients and 139 cases of allopurinol tolerant controls were enrolled in this study during 2005 to 2021.

RESULTS

The results of genome-wide DNA methylation assay of 62 patients revealed that ITGB2 showed strong discriminative ability of allopurinol-induced SCAR in both HLA-B*58:01 positive and negative patients with AUC value of 0.9364 (95% CI 0.8682-1.000). In validation study, significant hypermethylation of ITGB2 were further validated in allopurinol-induced SCAR patients compared to tolerant controls, especially in those without HLA-B*58:01(AUC value of 0.8814 (95% CI 0.7121-1.000)). Additionally, the methylation levels of 2 sites on ITGB2 were associated with SCAR phenotypes. Combination of HLA-B*58:01 genotyping and ITGB2 methylation status could improve the prediction accuracy of allopurinol-induced SCAR with the AUC value up to 0.9387 (95% CI 0.9089-0.9684), while the AUC value of HLA-B*58:01 genotyping alone was 0.8557 (95% CI 0.8030-0.9083).

CONCLUSIONS

Our study uncovers differentially methylated genes between allopurinol-induced SCAR patients and tolerant controls with positive or negative HLA-B*58:01 allele and provides the novel epigenetic marker that improves the prediction accuracy of genetic testing for prevention of allopurinol-induced SCAR.

DRESS syndrome: A literature review and treatment algorithm

Drug reaction with eosinophilia and systemic symptoms, known by its acronym in English as DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms), clinically manifests with fever, facial edema, lymphadenopathy, a morbilliform rash, and organ involvement. Laboratory results reveal leukocytosis, atypical lymphocytes, eosinophilia, and alterations of liver and kidney function tests. The actual incidence of DRESS is unknown, because it may vary depending on the type of medication and the immune status of each patient; also, because many cases remain undiagnosed or untreated. The drugs most associated with DRESS include antiepileptics, antibiotics, antituberculosis, and non-steroidal anti-inflammatory agents (NSAIDs). Its diagnosis is sometimes made late and can become a challenge. The diagnostic criteria proposed by the international Registry of Severe Cutaneous Adverse Reactions (RegiSCAR) help to establish the diagnosis through a score system based on clinical and laboratory findings. The first step to identify the culprit is a thorough clinical history that includes all suspects, emphasizing those most known to cause DRESS syndrome according to the context and the literature. A skin biopsy may also be helpful in the diagnostic process. Patch testing is the test of choice to search for the culprit in cases of DRESS. Regarding prognosis, the estimated mortality due to DRESS is 3.8%. The main causes of mortality include fulminant hepatitis and liver necrosis. Several indicators of poor prognosis have been identified and these include an eosinophil count above 6000 × 10³/μL, thrombocytopenia, pancytopenia, leukocytosis and coagulopathy. This article aims to review the evidence available regarding the epidemiology, pathophysiology, clinical and laboratory findings, diagnosis, and treatment of DRESS.

A lifetime economic research of universal HLA-B*58:01 genotyping or febuxostat initiation therapy in Chinese gout patients with mild to moderate chronic kidney disease

OBJECTIVE

To evaluate Chinese long-term economic impact of universal human leukocyte antigen B (HLA-B)*58:01 genotyping-guided urate-lowering therapy or febuxostat initiation therapy for gout patients with mild to moderate chronic kidney disease (CKD) from perspective of healthcare system.

METHODS

A Markov model embedded in a decision tree was structured including four mutually exclusive health states (uncontrolled-on-therapy, controlled-on-therapy, uncontrolled-off-therapy, and death). Mainly based on Chinese real-world data, the incremental costs per quality-adjusted life years (QALYs) gained were evaluated from three groups (universal HLA-B*58:01 testing strategy, and no genotyping prior to allopurinol or febuxostat initiation therapy) at 25-year time horizon. All costs were adjusted to 2021 levels based on Chinese Consumer Price Index and were discounted by 5% annually. One-way and probability sensitivity analysis were performed.

RESULTS

Among these three groups, universal HLA-B*58:01 genotyping was the most cost-effective strategy in base-case analysis according to Chinese average willingness-to-pay threshold of $37 654.50 per QALY. The based incremental cost-effectiveness ratio was $31784.55 per QALY, associated with 0.046 additional QALYs and $1463.81 increment costs per patient at a 25-year time horizon compared with no genotyping prior to allopurinol initiation strategy. Sensitivity analysis showed 64.3% robustness of these results.

CONCLUSION

From Chinese perspective of healthcare system, HLA-B*58:01 genotyping strategy was cost-effective for gout patients with mild to moderate CKD in mainland China, especially in the most developed area, such as Beijing and Shanghai. Therefore, we suggest China's health authorities choose the genotyping strategy and make different recommendations according to the differences of local conditions.

A Drug-Drug Interaction Study of a Novel Selective Urate Reabsorption Inhibitor, SHR4640, and Xanthine Oxidase Inhibitor, Febuxostat, in Patients With Primary Hyperuricemia

SHR4640 is a novel, selective urate reabsorption inhibitor. As the mode of action of SHR4640 differs from that of a xanthine oxidase inhibitor, such as febuxostat, coadministration of these drugs may be a treatment option for patients with primary hyperuricemia. We assessed the potential drug-drug interaction between SHR4640 and febuxostat. In this single-center, open-label, randomized, drug-drug interaction study, subjects received 80 mg febuxostat or 10 mg SHR4640 alone daily in the first week, whereas during the second week a combination of SHR4640 and febuxostat was administered daily to all subjects. Plasma concentrations of SHR4640 and febuxostat were analyzed. We compared their pharmacokinetic and pharmacodynamic parameters and assessed both safety and tolerability. Compared with febuxostat alone, the geometric mean ratios (90%CIs) of the maximum concentration (C_max ) and the area under the plasma concentration-time curve over the dosing interval τ (AUC_0-τ ) for febuxostat after coadministration were 1.284 (1.016 to 1.621) and 0.984 (0.876 to 1.106), respectively. The geometric mean ratios (90%CIs) of C_max and AUC_0-τ for SHR4640 after coadministration compared with SHR4640 alone were 0.910 (0.839 to 0.988) and 0.929 (0.893 to 0.966), respectively. Febuxostat had no effect on SHR4640 pharmacokinetic parameters, as the 90%CIs of the geometric mean ratios were all within the range of 0.80 to 1.25. The coadministration of febuxostat and SHR4640 was well tolerated. The coadministration of SHR4640 with febuxostat was not associated with any clinically relevant pharmacokinetic drug interactions. SHR4640 combined with febuxostat had a synergistic effect on reducing uric acid in the pharmacodynamics, with the AUC decreasing from 7440 to 3170 h μmol/L compared with febuxostat alone and from 5730 to 2960 h μmol/L compared with SHR4640 alone.

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS): Focus on the Pathophysiological and Diagnostic Role of Viruses

Drug reaction with eosinophilia and systemic symptoms (DRESS) is a heterogeneous, multiorgan and potentially life-threatening drug-hypersensitivity reaction (DHR) that occurs several days or weeks after drug initiation or discontinuation. DHRs constitute an emerging issue for public health, due to population aging, growing multi-organ morbidity, and subsequent enhanced drug prescriptions. DRESS has more consistently been associated with anticonvulsants, allopurinol and antibiotics, such as sulphonamides and vancomycin, although new drugs are increasingly reported as culprit agents. Reactivation of latent infectious agents such as viruses (especially Herpesviridae) plays a key role in prompting and sustaining aberrant T-cell and eosinophil responses to drugs and pathogens, ultimately causing organ damage. However, the boundaries of the impact of viral agents in the pathophysiology of DRESS are still ill-defined. Along with growing awareness of the multifaceted aspects of immune perturbation caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the ongoing SARS-CoV-2-related disease (COVID-19) pandemic, novel interest has been sparked towards DRESS and the potential interactions among antiviral and anti-drug inflammatory responses. In this review, we summarised the most recent evidence on pathophysiological mechanisms, diagnostic approaches, and clinical management of DRESS with the aim of increasing awareness on this syndrome and possibly suggesting clues for future research in this field.

Pharmacogenomics: current status and future perspectives

Inter-individual variability in drug response, be it efficacy or safety, is common and likely to become an increasing problem globally given the growing elderly population requiring treatment. Reasons for this inter-individual variability include genomic factors, an area of study called pharmacogenomics. With genotyping technologies now widely available and decreasing in cost, implementing pharmacogenomics into clinical practice - widely regarded as one of the initial steps in mainstreaming genomic medicine - is currently a focus in many countries worldwide. However, major challenges of implementation lie at the point of delivery into health-care systems, including the modification of current clinical pathways coupled with a massive knowledge gap in pharmacogenomics in the health-care workforce. Pharmacogenomics can also be used in a broader sense for drug discovery and development, with increasing evidence suggesting that genomically defined targets have an increased success rate during clinical development.

Delayed Drug Hypersensitivity Reactions: Molecular Recognition, Genetic Susceptibility, and Immune Mediators

Drug hypersensitivity reactions are classified into immediate and delayed types, according to the onset time. In contrast to the immediate type, delayed drug hypersensitivity mainly involves T lymphocyte recognition of the drug antigens and cell activation. The clinical presentations of such hypersensitivity are various and range from mild reactions (e.g., maculopapular exanthema (MPE) and fixed drug eruption (FDE)), to drug-induced liver injury (DILI) and severe cutaneous adverse reactions (SCARs) (e.g., Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP)). The common culprits of delayed drug hypersensitivity include anti-epileptics, antibiotics, anti-gout agents, anti-viral drugs, etc. Delayed drug hypersensitivity is proposed to be initiated by different models of molecular recognition, composed of drug/metabolite antigen and endogenous peptide, HLA presentation, and T cell receptor (TCR) interaction. Increasing the genetic variants of HLA loci and drug metabolic enzymes has been identified to be responsible for delayed drug hypersensitivity. Furthermore, preferential TCR clonotypes, and the activation of cytotoxic proteins/cytokines/chemokines, are also involved in the pathogenesis of delayed drug hypersensitivity. This review provides a summary of the current understanding of the molecular recognition, genetic susceptibility, and immune mediators of delayed drug hypersensitivity.

The immediate adverse drug reactions induced by ShenMai Injection are mediated by thymus-derived T cells and associated with RhoA/ROCK signaling pathway

Introduction

The mechanism of the immediate adverse drug reactions (ADRs) induced by ShenMai injection (SMI) has not been completely elucidated. Within 30 minutes, the ears and lungs of mice injected with SMI for the first time showed edema and exudation reactions. These reactions were different from the IV hypersensitivity. The theory of pharmacological interaction with immune receptor (p-i) offered a new insight into the mechanisms of immediate ADRs induced by SMI.

Methods

In this study, we determined that the ADRs were mediated by thymus-derived T cells through the different reactions of BALB/c mice (thymus-derived T cell normal) and BALB/c nude mice (thymus-derived T cell deficient) after injecting SMI. The flow cytometric analysis, cytokine bead array (CBA) assay and untargeted metabolomics were used to explain the mechanisms of the immediate ADRs. Moreover, the activation of the RhoA/ROCK signaling pathway was detected by western blot analysis.

Results

In BALB/c mice, the vascular leakage and histopathology results showed the occurrence of the immediate ADRs induced by SMI. The flow cytometric analysis revealed that CD4⁺ T cell subsets (Th1/Th2, Th17/Treg) were imbalanced. And the levels of cytokines such as IL-2, IL-4, IL12P70 and INF-γ increased significantly. However, in BALB/c nude mice, all the indicators mentioned above have not changed significantly. The metabolic profile of both BALB/c mice and BALB/c nude mice was significantly changed after injecting SMI, and the notable increase in lysolecithin level might have a greater association with the immediate ADRs induced by SMI. The Spearman correlation analysis revealed that LysoPC (18:3(6Z,9Z,12Z)/0:0) showed a significant positive correlation with cytokines. After injecting SMI, the levels of RhoA/ROCK signaling pathway-related protein increased significantly in BALB/c mice. Protein-protein interaction (PPI) showed that the increased lysolecithin levels might be related to the activation of the RhoA/ROCK signaling pathway.

Discussion

Together, the results of our study revealed that the immediate ADRs induced by SMI were mediated by thymus-derived T cells, and elucidated the mechanisms of such ADRs. This study provided new insights into the underlying mechanism of immediate ADRs induced by SMI.

Cost-effectiveness analysis of HLA-B*13:01 screening for the prevention of co-trimoxazole-induced severe cutaneous adverse reactions among HIV-infected patients in Thailand

Studies found a strong association between HLA-B*13:01 allele and co-trimoxazole-induced severe cutaneous adverse reactions (SCARs). Genetic screening before initiation of co-trimoxazole may decrease the incidence of co-trimoxazole-induced SCARs. This study aims to evaluate the cost-effectiveness of HLA-B*13:01 screening before co-trimoxazole initiation in HIV-infected patients in Thailand. A combination of a decision tree model and a Markov model was used to estimate lifetime costs and outcomes of two strategies including 1) HLA-B*13:01 screening before co-trimoxazole initiation and 2) usual practice from a societal perspective. Alternative drugs are not considered because dapsone (the second-line drug) also presents a genetic risk. Input parameters were obtained from literature, government documents, and part of the TREAT Asia HIV Observational Database (TAHOD). One-way sensitivity analyses and probabilistic analyses were performed to determine robustness of the findings. HLA-B*13:01 screening resulted in 0.0061 quality-adjusted life years (QALYs) loss with an additional cost of 370 THB ($11.84). At the cost-effectiveness threshold of 160,000 THB ($5,112.85), the probability of the genetic screening strategy being cost-effective is 9.54%. This analysis demonstrated that HLA-B*13:01 allele screening before initiation of co-trimoxazole among HIV-infected patients is unlikely to be cost-effective in Thailand. Our findings will help policymakers make an evidence-informed decision making.

Pulmonary sarcoidosis: A novel sequelae of drug reaction with eosinophilia and systemic symptoms: A case report

BACKGROUND

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is an uncommon yet serious adverse drug hypersensitivity reaction with the presentations including rash, fever, lymphadenopathy, and internal organ involvement. Sarcoidosis is a systematic granulomatous disease with unknown etiology. We herein report a case of pulmonary sarcoidosis secondary to allopurinol-induced DRESS.

CASE SUMMARY

A 37-year-old man with a history of hyperuricemia was treated with allopurinol for three weeks at a total dose of 7000 milligrams before developing symptoms including anorexia, fever, erythematous rash, and elevated transaminase. The patient was diagnosed with DRESS and was treated with prednisone for 6 mo until all the symptoms completely resolved. Three months later, the patient presented again because of a progressively worsening dry cough. His chest computed tomography images showed bilateral lung parenchyma involvement with lymph node enlargement, which was confirmed to be nonnecrotizing granuloma by pathological examination. Based on radiologic and pathological findings, he was diagnosed with sarcoidosis and was restarted on treatment with prednisone, which was continued for another 6 mo. Reexamination of chest imaging revealed complete resolution of parenchymal lung lesions and a significant reduction in the size of the mediastinal and hilar lymph nodes. Following a 6-month follow-up of completion of treatment, the patient's clinical condition remained stable with no clinical evidence of relapse.

CONCLUSION

This is the first case in which pulmonary sarcoidosis developed as a late complication of allopurinol-induced DRESS. The case indicated that the autoimmune reaction of DRESS may play an important role in the pathogenesis of sarcoidosis.

Pathophysiology of drug hypersensitivity

Drug hypersensitivity reactions (DHRs) are type B adverse drug reactions (ADRs) traditionally defined as unpredictable, dose independent and not related to the drug pharmacology. DHRs, also called drug allergy if the immune system involvement is confirmed, represent around one-sixth of all ADRs and can cause major clinical problems due to their vague clinical presentation and irregular time course. Understanding the underlying pathophysiology of DHRs is very important for their diagnosis and management. Multiple layers of evidence exist pointing to the involvement of the immune system in DHRs. Recent data have led to a paradigm shift in our understanding of the exact pathophysiology of these reactions. Numerous hypotheses proposing explanation on how a low molecular weight drug molecule can elicit an immune reaction have been proposed. In addition to the classical "hapten" hypothesis, the reactive metabolite hypothesis, the pharmacological interaction with the immune system (p-i) concept, the danger/injury hypothesis and the altered peptide repertoire hypothesis have been proposed. We here introduce the inflammasome activation hypothesis and the cross-reactivity hypothesis as additional models explaining the pathophysiology of DHRs. Available data supporting these hypotheses are briefly summarized and discussed. We also introduced the cross-reactivity model, which may provide a platform to appreciate the potential role played by other factors leading to the activation of the immune system. We believe that although the drug in question could be the trigger of the reaction, the components of the immune system mediating the reaction do not act in isolation but rather are affected by the proinflammatory milieu occurring at the time of the reaction. This review attempts to summarize the available evidence to further illustrate the pathophysiology of DHRs.