Human leukocyte antigen genotypes and trial of desensitization in patients with oxcarbazepine-induced skin rash: a pilot study

Pharmacogenetics and Oxcarbazepine in Children and Adolescents: Beyond HLA-B*15:02

Background: Oxcarbazepine is thought to be better-tolerated and less susceptible to drug-drug interactions than its predecessor, carbamazepine. Genetic testing for HLA-B*15:02 is recommended in specific populations to identify those at high risk of severe hypersensitivity reactions; however, other pharmacologic and pharmacogenetic factors that can impact drug disposition may be involved. Methods: We present a case of an 8-year-old boy treated with oxcarbazepine who developed drug reaction with eosinophilia and systemic symptoms (DRESS) with Stevens-Johnsons syndrome overlap and was negative for HLA-B*15:02. We review the extant literature related to oxcarbazepine disposition, and potential pharmacogenetic variants in aldoketoreductase 1C (AKR1C)2-4 that may contribute to this risk. Results: Genetic variability in oxcarbazepine disposition pathways may contribute to tolerability and toxicity, including the development of hypersensitivity reactions. Conclusions: While preemptive genetic testing for HLA-B*15:02 in individuals of Asian ancestry is recommended to prevent severe hypersensitivity reactions to oxcarbazepine, oxcarbazepine concentrations and AKR1C variation may contribute to the risk of severe adverse reactions. We provide recommendations for future study to elucidate whether these individual factors are important for reducing the risk of severe adverse events.

Use of Rapid Drug Desensitization in Delayed Hypersensitivity Reactions to Chemotherapy and Monoclonal Antibodies

Background:

Rapid drug desensitization (RDD) allows first-line therapies in patients with immediate drug hypersensitivity reactions (DHR) to chemotherapeutic drugs (ChD) and monoclonal antibodies (mAb). Desensitization in delayed drug reactions has traditionally used slow protocols extending up to several weeks; RDD protocols have been scarcely reported.

Patients and Method:

We retrospectively analyzed the patients referred to the Allergy Department, who had experienced a delayed DHR (> 6 h) related to a ChD or mAb and underwent an RDD protocol. The rate of successful administration of the offending drug and the presence of adverse reactions were evaluated.

Results:

A total of 93 RDDs were performed in 11 patients (including 6 men and 5 women, with a median age of 61 years). The primary DHR were maculopapular exanthema (MPE) (8), generalized delayed urticaria (1), MPE with pustulosis and facial edema (1), and facial edema with desquamative eczema (1). The meantime for the onset of symptoms was 3 days (range 1–16 days). RDD was performed using a protocol involving 8–13 steps, with temozolomide (25), bendamustine (4), rituximab (9), infliximab (24), gemcitabine (23), and docetaxel (8), within 4.6–6.5 h. Sixteen breakthrough reactions were reported during the RDD (17.2 %) in 5 patients; all were mild reactions including 11 delayed and 5 immediate reactions. All patients completed their treatment.

Conclusions:

RDD is a potentially safe and effective procedure in patients suffering from delayed reactions to ChD and mAb. It allows them to receive full treatment in a short period, thereby reducing time and hospital visits.

Reintroduction of oxcarbazepine after allergic reaction in two pediatric patients with epilepsy

Allergic reactions are common reasons for withdrawal of oxcarbazepine treatment in patients with epilepsy. However, some patients are not responsive to other antiseizure medications. Herein, two pediatric patients with epilepsy and allergic to oxcarbazepine to whom oxcarbazepine therapy was successfully reintroduced are described. The reintroduction strategy used in this study was simple, feasible, and suitable for the reintroduction of oxcarbazepine in pediatric patients with epilepsy.

A new rapid titration protocol for lamotrigine that reduces the risk of skin rash

Objective

Lamotrigine is one of the most widely used antiepileptic drugs, but it has a critical issue of a skin rash if the starting dose is too high or the escalation rate is too rapid. We investigated the efficacy and safety of a novel and rapid titration protocol for lamotrigine that takes only 11 days to reach a daily dose of 200 mg.

Methods

We prospectively enrolled 33 adult patients (age 18‐85) who were diagnosed with epilepsy and started lamotrigine administration for the first time at a single tertiary hospital. Our new protocol starts with a subthreshold dose of the drug and then administers a stepwise‐incremental dose until reaching the full therapeutic dose within 11 days.

Results

Of 29 patients analyzed, only two (6.9%) experienced idiosyncratic skin rash before the first follow‐up visit at 2 weeks (±3 days). In addition, a therapeutic concentration was reached in more than 75% of studied patients after 2 weeks of lamotrigine administration.

Significance

These findings demonstrate the value of the novel tolerance induction protocol for lamotrigine, which could widen the available application of lamotrigine in various situations. However, this study is a preliminary study limited by a small number of patients and its nonrandomized and open‐label design, so the current protocol needs more rigorous clinical evaluations before the application to the real clinical setting.

Desensitization to Oxcarbazepine: Long-Term Efficacy and Tolerability

BACKGROUND AND PURPOSE

Antiepileptic drug (AED)-associated cutaneous adverse drug reactions can lead to the discontinuation of medications. The aim of this study was to determine the long-term efficacy and safety of performing desensitization to oxcarbazepine.

METHODS

This study involved 20 patients who exhibited cutaneous adverse drug reactions associated with oxcarbazepine use between July 2009 and March 2016 at Samsung Medical Center. All of the participants had to discontinue oxcarbazepine despite presenting initially positive responses. Human leukocyte antigen genotyping was performed to detect the genetic predisposition to Stevens-Johnson syndrome. The desensitization to oxcarbazepine was performed with a starting dosage of 0.1 mg/day. Efficacy was evaluated by comparing the frequency of seizures before and at 1 and 3 years after desensitization. Adverse events occurring during desensitization and the retention rate after desensitization were also investigated.

RESULTS

Nineteen patients (95%) safely completed the desensitization protocol. One withdrew owing to emotional problems that appeared to be associated with oxcarbazepine. The follow-up period was 4.6±1.2 years (mean±SD), and oxcarbazepine was maintained for more than 3 years after desensitization in 15 patients (83.3%). The response rates were 84.2% and 77.8% at 1 and 3 years after desensitization, respectively. Eight patients remained seizure-free for 3 years, and two discontinued all AEDs. Transient adverse reactions such as mild rash and itching were reported by five patients during desensitization.

CONCLUSIONS

This study has demonstrated the long-term efficacy and safety of desensitization to oxcarbazepine in patients exhibiting cutaneous adverse drug reactions. This favorable outcome should encourage the implementation of desensitization in patients presenting with hypersensitivity to oxcarbazepine as an alternative strategy in clinical practice.

HLA-B*40:02 and DRB1*04:03 are risk factors for oxcarbazepine-induced maculopapular eruption

OBJECTIVE

Oxcarbazepine (OXC) is a widely used antiepileptic drug for the treatment of partial seizures that was developed through structural variation of carbamazepine. Although OXC has a lower risk of cutaneous adverse drug reactions (cADRs) than carbamazepine, cADRs ranging from maculopapular eruption (MPE) to the more severe Stevens-Johnson syndrome and toxic epidermal necrolysis still limit the use of OXC in some patients. A few human leukocyte antigen (HLA)-related genetic risk factors for carbamazepine-induced cADRs have been identified. However, the HLA-related genetic risk factors associated with OXC-induced cADRs are unknown.

METHODS

A total of 40 patients who experienced OXC-induced MPE and 70 patients who were tolerant to OXC treatment were included in the study. Genomic DNA was extracted from the peripheral blood of these patients, and high-resolution HLA genotyping was performed.

RESULTS

The HLA-B*40:02 and HLA-DRB1*04:03 alleles were significantly associated with OXC-induced MPE compared with the OXC-tolerant group (odds ratio [OR] 4.33, p = 0.018 and OR 14.64, p = 0.003, respectively) and the general Korean population (OR 4.04, p = 0.001 and OR 3.11, p = 0.019, respectively). The HLA-B*15:01 genetic frequency was significantly lower in the OXC-MPE group compared to the OXC-tolerant group (OR 0.18, p = 0.016) and the Korean population (OR 0.22, p = 0.030). The allele frequencies of well-known HLA-related risk factors for carbamazepine-induced cADRs (HLA-B*15:02, A*31:01 and B*15:11) were not different among the three groups.

SIGNIFICANCE

This study is the first to demonstrate an association of HLA-B*40:02 and HLA-DRB1*04:03 with OXC hypersensitivity using a large cohort of patients with OXC-induced MPE. These findings should be confirmed in future studies in different ethnic groups.

Valproic acid hypersensitivity and desensitization

Rash, a hypersensitivity reaction, is a common cause of withdrawal from an effective antiepileptic drug (AED) in patients with epilepsy. We present a case of successful desensitization to valproic acid in a 12-year-old male with childhood absence epilepsy and a hypersensitivity reaction, whose epilepsy did not respond to other AEDs. Desensitization is a practical therapeutic solution for patients who develop a non-life-threatening hypersensitivity reaction to an AED for which there may be no substitute.