Chun-Bing Chen

Risk and association of HLA with oxcarbazepine-induced cutaneous adverse reactions in Asians

Objective: To investigate the risk and genetic association of oxcarbazepine-induced cutaneous adverse reactions (OXC-cADRs), including Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), in Asian populations (Chinese and Thai). Methods: We prospectively enrolled patients with OXC-cADRs in Taiwan and Thailand from 2006 to 2014, and analyzed the clinical course, latent period, drug dosage, organ involvement, complications, and mortality. We also investigated the carrier rate of HLA-B*15:02 and HLA-A*31:01 of patients with OXC-cADRs and compared to OXC-tolerant controls. The incidence of OXC-SJS/TEN was compared with carbamazepine (CBZ)–induced SJS/TEN according to the nationwide population dataset from the Taiwan National Health Insurance Research Database. Results: We enrolled 50 patients with OXC-cADRs, including 20 OXC-SJS/TEN and 6 u2009drug reaction with eosinophilia and systemic symptoms, of Chinese patients from Taiwan and Thai patients from Thailand. OXC-cADRs presented with less clinical severity including limited skin detachment (all ≦5%) and no mortality. There was a significant association between HLA-B*15:02 and OXC-SJS (p = 1.87 × 10−10; odds ratio 27.90; 95% confidence interval [CI] 7.84–99.23) in Chinese and this significant association was also observed in Thai patients. The positive and negative predictive values of HLA-B*15:02 for OXC-SJS/TEN were 0.73% and 99.97%, respectively. HLA-A*31:01 was not associated with OXC-cADRs. The incidence and mortality of OXC-SJS/TEN was lower than CBZ-STS/TEN in new users (p = 0.003; relative risk 0.212; 95% CI 0.077–0.584). Conclusions: Our findings suggest that HLA-B*15:02 is significantly associated with OXC-SJS in Asian populations (Chinese and Thai). However, the severity and incidence of OXC-SJS/TEN are less than that of CBZ-SJS/TEN. The need for preemptive HLA-B*15:02 screening should be evaluated further.

Interleukin-15 Is Associated with Severity and Mortality in Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis

Early diagnosis and prognosis monitoring for Stevens-Johnson syndrome/toxic epidermal necrolysis (TEN) still remain a challenge. This study aims to explore any cytokine/chemokine with prognostic potential in Stevens-Johnson syndrome/TEN. Through screening a panel of 28 serological factors, IL-6, IL-8, IL-15, tumor necrosis factor-α, and granulysin were upregulated in patients with Stevens-Johnson syndrome/TEN and selected for the further validation in total 155 patients with Stevens-Johnson syndrome/TEN, including 77 from Taiwan and 78 from the Registry of Severe Cutaneous Adverse Reactions. Among these factors evaluated, the levels of IL-15 (rxa0= 0.401; Pxa0< 0.001) and granulysin (rxa0= 0.223; Pxa0= 0.026) were significantly correlated with the disease severity in 112 samples after excluding patients with insufficient data to calculate the score of TEN. In addition, IL-15 was also associated with mortality (Pxa0= 0.002; odds ratio, 1.09; 95% confidence interval, 1.03-1.14; Pxa0= 0.001; adjusted odds ratio, 1.10; 95% confidence interval, 1.04-1.16). Consistent results were obtained after the exclusion of Taiwanese patients with sepsis to rule out possible confounders. Moreover, IL-15 was shown to enhance cytotoxicity of cultured natural killer cells and blister cells from patients with TEN. Our findings highlight a usefulness of IL-15 in prognosis monitoring and therapeutic intervention of this devastating condition.

Randomized, controlled trial of TNF-α antagonist in CTL-mediated severe cutaneous adverse reactions

BACKGROUND. Cytotoxic T lymphocyte–mediated (CTL-mediated) severe cutaneous adverse reactions (SCARs), including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), are rare but life-threatening adverse reactions commonly induced by drugs. Although high levels of CTL-associated cytokines, chemokines, or cytotoxic proteins, including TNF-&agr; and granulysin, were observed in SJS-TEN patients in recent studies, the optimal treatment for these diseases remains controversial. We aimed to evaluate the efficacy, safety, and therapeutic mechanism of a TNF-&agr; antagonist in CTL-mediated SCARs. METHODS. We enrolled 96 patients with SJS-TEN in a randomized trial to compare the effects of the TNF-&agr; antagonist etanercept versus traditional corticosteroids. RESULTS. Etanercept improved clinical outcomes in patients with SJS-TEN. Etanercept decreased the SCORTEN-based predicted mortality rate (predicted and observed rates, 17.7% and 8.3%, respectively). Compared with corticosteroids, etanercept further reduced the skin-healing time in moderate-to-severe SJS-TEN patients (median time for skin healing was 14 and 19 days for etanercept and corticosteroids, respectively; P = 0.010), with a lower incidence of gastrointestinal hemorrhage in all SJS-TEN patients (2.6% for etanercept and 18.2% for corticosteroids; P = 0.03). In the therapeutic mechanism study, etanercept decreased the TNF-&agr; and granulysin secretions in blister fluids and plasma (45.7%–62.5% decrease after treatment; all P < 0.05) and increased the Treg population (2-fold percentage increase after treatment; P = 0.002), which was related to mortality in severe SJS-TEN. CONCLUSIONS. The anti–TNF-&agr; biologic agent etanercept serves as an effective alternative for the treatment of CTL-mediated SCARs. TRIAL REGISTRATION. ClinicalTrials.gov NCT01276314. FUNDING. Ministry of Science and Technology of Taiwan.

An Updated Review of the Molecular Mechanisms in Drug Hypersensitivity

Drug hypersensitivity may manifest ranging from milder skin reactions (e.g., maculopapular exanthema and urticaria) to severe systemic reactions, such as anaphylaxis, drug reactions with eosinophilia and systemic symptoms (DRESS)/drug-induced hypersensitivity syndrome (DIHS), or Stevens–Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN). Current pharmacogenomic studies have made important strides in the prevention of some drug hypersensitivity through the identification of relevant genetic variants, particularly for genes encoding drug-metabolizing enzymes and human leukocyte antigens (HLAs). The associations identified by these studies are usually drug, phenotype, and ethnic specific. The drug presentation models that explain how small drug antigens might interact with HLA and T cell receptor (TCR) molecules in drug hypersensitivity include the hapten theory, the p-i concept, the altered peptide repertoire model, and the altered TCR repertoire model. The broad spectrum of clinical manifestations of drug hypersensitivity involving different drugs, as well as the various pathomechanisms involved, makes the diagnosis and management of it more challenging. This review highlights recent advances in our understanding of the predisposing factors, immune mechanisms, pathogenesis, diagnostic tools, and therapeutic approaches for drug hypersensitivity.

Chromoblastomycosis in Taiwan: A report of 30 cases and a review of the literature

Chromoblastomycosis (CBM) is an implantation mycosis characterized by the presence of pigmented muriform cells in tissue. CBM is endemic in Taiwan, but only three formal cases have been reported to date because of underreporting. To describe and update its epidemiologic features, we report a series of 30 cases between 2003 and 2016 at a single medical center. Patients were predominately male (2.75:1). The mean age of onset was 65.9 years, and disease duration ranged from 2 months to 20 years. Diabetes was the most common comorbidity, and extremities were the most frequent sites of involvement. The lesions presented as papuloplaque, verrucous, cicatricial, targetoid, or mixed types. The dermoscopic features were variable, including red dots, white vague areas, black globules, and sand-like patterns. Among 10 Fonsecaea isolates further identified by sequencing the ITS regions of ribosomal DNA, nine were F. monophora and one was F. nubica. All but one patient received either systemic antifungal agents, surgical excision, or both. Surgical excision achieved a higher complete remission rate than the other forms of treatment did.

The Medication Risk of Stevens–Johnson Syndrome and Toxic Epidermal Necrolysis in Asians: The Major Drug Causality and Comparison With the US FDA Label

Specific ethnic genetic backgrounds are associated with the risk of Stevens–Johnson syndrome / toxic epidermal necrolysis (SJS/TEN) especially in Asians. However, there have been no large cohort, multiple‐country epidemiological studies of medication risk related to SJS/TEN in Asian populations. Thus, we analyzed the registration databases from multiple Asian countries who were treated during 1998–2017. A total 1,028 SJS/TEN cases were identified with the algorithm of drug causality for epidermal necrolysis. Furthermore, those medications labeled by the US Food and Drug Administration (FDA) as carrying a risk of SJS/TEN were also compared with the common causes of SJS/TEN in Asian countries. Oxcarbazepine, sulfasalazine, COX‐II inhibitors, and strontium ranelate were identified as new potential causes. In addition to sulfa drugs and beta‐lactam antibiotics, quinolones were also a common cause. Only one acetaminophen‐induced SJS was identified, while several medications (e.g., oseltamivir, terbinafine, isotretinoin, and sorafenib) labeled as carrying a risk of SJS/TEN by the FDA were not found to have caused any of the cases in the Asian countries investigated in this study.

Pharmacogenomics and Cutaneous Adverse Drug Reactions

Cutaneous adverse drug reactions (cADRs) are unpredictable and may range from mild maculopapular exanthema (MPE) to life-threatening severe cutaneous adverse drug reactions (SCARs), including drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens–Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). Increasing pharmacogenomic studies showed specific HLA alleles are strongly associated with cADRs. The pathogenic checkpoints of cADRs include genetic polymorphisms affecting the immune synapse of HLA/drugs/T cell receptor interactions, specific HLA loci, T cell-mediated responses, and drug metabolism. Recently, pharmacogenomic screening for specific HLA alleles or high-risk genes prior to drug prescriptions to prevent cADRs has been widely implemented in clinical practice.

The function of HLA-B*13:01 involved in the pathomechanism of dapsone-induced severe cutaneous adverse reactions

Dapsone-induced hypersensitivity reactions may cause severe cutaneous adverse reactions, such as drug reaction with eosinophilia and systemic symptoms (DRESS). It has been reported that HLA-B*13:01 is strongly associated with dapsone-induced hypersensitivity reactions among leprosy patients. However, the phenotype specificity and detailed immune mechanism of HLA-B*13:01 remain unclear. We investigated the genetic predisposition, HLA-B*13:01 function, and cytotoxic T cells involved in the pathogenesis of dapsone-induced severe cutaneous adverse reactions. We enrolled patients from Taiwan and Malaysia with DRESS and maculopapular eruption with chronic inflammatory dermatoses. Our results showed that the HLA-B*13:01 allele was present in 85.7% (6/7) of patients with dapsone DRESS (odds ratioxa0= 49.64, 95% confidence intervalxa0= 5.89-418.13; corrected Pxa0= 2.92xa0× 10-4) but in only 10.8% (73/677) of general population control individuals in Taiwan. The level of granulysin, the severe cutaneous adverse reaction-specific cytotoxic protein released from cytotoxic T cells, was increased in both the plasma of DRESS patients (36.14 ± 9.02 ng/ml, P < 0.05) and inxa0vitro lymphocyte activation test (71.4%, 5/7 patients) compared with healthy control individuals. Furthermore, dapsone-specific cytotoxic T cells were significantly activated when co-cultured with HLA-B*13:01-expressing antigen presenting cells in the presence of dapsone (3.9-fold increase, compared with cells with no HLA-B*13:01 expression; P < 0.01). This study indicates that HLA-B*13:01 is strongly associated with dapsone DRESS and describes a functional role for the HLA-restricted immune mechanism induced by dapsone.

The effect of levamisole in the treatment of recalcitrant recurrent erythema multiforme major: An observational study

BACKGROUNDnErythema multiforme major (EMM) is an immune-mediated mucocutaneous eruption mostly triggered by herpes simplex virus (HSV) infection. A vicious circle of recurrence may be developed due to HSV reactivation and prolonged use of systemic corticosteroids to control EMM. Levamisole is an immunomodulator and has been applied to prevent relapses of recurrent HSV infection.nnnOBJECTIVEnTo evaluate the clinical efficacy and safety of levamisole in patients with recalcitrant recurrent EMM.nnnMETHODSnWe enrolled 23 patients with recurrent EMM treated with levamisole and 24 controls, and analyzed the demographics, treatments and outcomes.nnnRESULTSnPatients with recurrent EMM for years (mean 3.99u2009±u20092.71) showed significantly reduced recurrences after various durations of levamisole treatment (recurrences after and before treatment: 3.98u2009±u20091.04 vs 6.75u2009±u20091.45 times per year, pu2009=u20091.33x10-8). The recurrences of EMM also significantly reduced after levamisole treatment comparing to that of patients without levamisole treatment (pu2009=u20093.77x10-9). No patient was reported to have severe side effects during or after levamisole treatment.nnnCONCLUSIONSnLevamisole was effective in reducing recurrences of recalcitrant recurrent EMM and can thus be considered an alternative or add-on therapy for this disorder.

HLA Alleles and CYP2C9*3 as Predictors of Phenytoin Hypersensitivity in East Asians

To develop a pre‐emptive genetic test that comprises multiple predisposing alleles for the prevention of phenytoin‐related severe cutaneous adverse reactions (SCARs), three sets of patients with phenytoin‐SCAR and drug‐tolerant controls from Taiwan, Thailand, and Japan, were enrolled for this study. In addition to cytochrome P450 (CYP)2C9*3, we found that HLA‐B*13:01, HLA‐B*15:02, and HLA‐B*51:01 were significantly associated with phenytoin hypersensitivity with distinct phenotypic specificities. Strikingly, we showed an increase in predictive sensitivity of concurrently testing CYP2C9*3/HLA‐B*13:01/HLA‐B*15:02/HLA‐B*51:01 from 30.5–71.9% for selecting the individuals with the risk of developing phenytoin‐SCAR in Taiwanese cohorts, accompanied by a specificity of 77.7% (combined sensitivity, 64.7%; specificity, 71.9% for three Asian populations). Meta‐analysis of the four combined risk alleles showed significant associations with phenytoin‐SCAR in three Asian populations. In conclusion, combining the assessment of risk alleles of HLA and CYP2C9 potentiated the usefulness of predictive genetic tests to prevent phenytoin hypersensitivity in Asians.