Epidemiology of hypersensitivity drug reactions

Granulysin is a key mediator for disseminated keratinocyte death in Stevens-Johnson syndrome and toxic epidermal necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening adverse drug reactions characterized by massive epidermal necrosis, in which the specific danger signals involved remain unclear. Here we show that blister cells from skin lesions of SJS-TEN primarily consist of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, and both blister fluids and cells were cytotoxic. Gene expression profiling identified granulysin as the most highly expressed cytotoxic molecule, confirmed by quantitative PCR and immunohistochemistry. Granulysin concentrations in the blister fluids were two to four orders of magnitude higher than perforin, granzyme B or soluble Fas ligand concentrations, and depleting granulysin reduced the cytotoxicity. Granulysin in the blister fluids was a 15-kDa secretory form, and injection of it into mouse skin resulted in features mimicking SJS-TEN. Our findings demonstrate that secretory granulysin is a key molecule responsible for the disseminated keratinocyte death in SJS-TEN and highlight a mechanism for CTL- or NK cell--mediated cytotoxicity that does not require direct cellular contact.

Questionnaire-based survey of lifetime-prevalence and character of allergic drug reactions in German children

Data on the epidemiology of adverse drug reactions (ADR), especially allergic drug reactions, in children are rare. The reported prevalence of ADR in pediatric populations varies a lot, depending on type of the study and the country where the data were collected. In order to assess the prevalence of ADR and allergic drug reactions in a population of German children, we conducted a study in a German pediatric university hospital. A questionnaire concerning occurrence and character of ADR was distributed to all parents presenting their children in the hospital for planned admissions or in the emergency department from May 2004 to November 2004. Additional telephone interviews were conducted to specify the reported symptoms in ambiguous cases. One thousand four hundred forty-seven questionnaires were collected. The reported life-time prevalence of ADR according to the information given by the parents was 7.5% (108/1447). Six of the reactions were severe, three children had experienced anaphylactic reactions. In 4.2% (61/1447), the history was suspicious for a potential allergic mechanism because of an immediate or late phase cutaneous drug reaction. In this group, the suspected drugs were antibiotics in 85% (32.7% aminopenicillins, 29.5% other penicillins, 11.5% cefaclor, 8.2% macrolides and 18% others), antiphlogistic and respiratory drugs in 4.9% each and vaccines and contrast media in 3.3% each. There was a higher percentage of children under the age of four suffering from ADR. This trend was not significant when analyzing only the allergic reactions. Forty-four percent of the parents stated, their children suffer from drug allergy, although a clear non-allergic reaction was described. Both, ADR and allergic drug reactions are frequent phenomena in children. It is important to monitor drug therapy for any adverse reaction in order to inform the parents about the character of the adverse reaction, the necessary consequences and to initiate further diagnostic procedures.

Cytokine Profiling in Abacavir Hypersensitivity Patients

Background

Abacavir hypersensitivity in genetically susceptible individuals implicates an abacavir-specific T-cell response to either the parent drug or a metabolite generated in vivo. We have analysed the cytokine profile in antigen-presenting cells and the T-lymphocytes that are involved in the pathological immune response to abacavir.

Methods

In this study, we compared abacavir-specific cytokine responses in cultured peripheral blood mononuclear cells (PBMCs) from HIV-infected abacavir hypersensitive, tolerant and naive individuals. Cells were cultured in the presence or absence of abacavir. Cytokine expression was determined by microarray analysis, enzyme-linked immunosorbent assays and flow cytometry.

Results

We demonstrated using in vitro models of immune activation that the production of interferon-γwas specifically induced by abacavir treatment in PBMCs obtained from hypersensitive patients carrying the HLA-B*5701 allele (median 123.86 compared with -30.83 for tolerant controls, P=0.001).

Conclusion

These results provide further insight into the immunological and metabolic basis of abacavir hypersensitivity syndrome. In vitro assays could assist in the identification of susceptible loci by providing a surrogate marker for the hypersensitivity reaction. Such a marker could be studied in unexposed individuals to shed further light on the immunopathogenesis of the abacavir hypersensitivity syndrome.

Management and preparedness for infusion and hypersensitivity reactions

BACKGROUND

Like nearly all systemic cancer therapies, monoclonal antibodies are associated with hypersensitivity reactions. This article reviews the characteristics and management of hypersensitivity reactions to monoclonal antibodies and commonly used chemotherapy agents.

METHODS

MEDLINE was searched for recent studies and reviews pertaining to hypersensitivity reactions with monoclonal antibodies (cetuximab, rituximab, trastuzumab, panitumumab, bevacizumab), platinum compounds (carboplatin, oxaliplatin), and taxanes (paclitaxel, docetaxel). Emphasis was placed on articles that provided practical information on hypersensitivity reaction management. Data found in the literature were supplemented with information from the package insert for each agent.

RESULTS

Severe hypersensitivity reactions are rare, with an incidence of < or =5%, provided patients receive proper premedication, close monitoring, and prompt intervention when symptoms occur. Hypersensitivity reactions to platinum compounds are generally consistent with type 1 hypersensitivity, occurring after multiple cycles of therapy. Reactions to taxanes and monoclonal antibodies produce similar symptoms, but are generally immediate, occurring during the first few minutes of the first or second infusion. However, 10%-30% of reactions to monoclonal antibodies are delayed, and may occur in later infusions, indicating the importance of close observation of the patient following administration. Mild-to-moderate reactions can be managed by temporary infusion interruption, reduction of the infusion rate, and symptom management. Rechallenge should be considered after complete resolution of all symptoms. Severe reactions may require treatment discontinuation.

CONCLUSION

Hypersensitivity or infusion reactions to platinum compounds are acquired; reactions to taxanes and monoclonal antibodies are immediate and typically occur during the first few minutes of the first infusion. The different time of onset should be considered when developing strategies for preventing and managing hypersensitivity reactions. The decision to rechallenge or discontinue treatment after a reaction occurs depends on the severity of the reaction and other clinical factors.

Drug allergy claims in children: from self-reporting to confirmed diagnosis

BACKGROUND

Poorly documented self-reported drug allergy (DAll) is a frequent problem in daily clinical practice and has a considerable impact on prescription choices. The diagnostic work-up of drug hypersensitivity (DHs) allows a better classification of the reactions and provides patients with more reliable information and recommendations for future treatments.

OBJECTIVE

To assess the prevalence of self-reported adverse drug reactions (ADRs) and DAll in a paediatric population and to investigate children reporting suspected DAll in order to achieve a firm diagnosis.

DESIGN

The first phase was based on a cross-sectional survey assessing the life occurrence of ADRs and self-reported DAll carried out at the outpatient clinic of a paediatric hospital. The second phase was based on the diagnostic work-up in children with parent-reported DAll, including detailed anamnesis and in vitro and in vivo investigations (skin and provocation tests). Participants One thousand four hundred and twenty-six parents responded to the initial survey. Sixty of the 67 patients with reported DAll were evaluated at the allergy clinic.

RESULTS

The prevalences of self-reported ADRs and DAll were 10.2% and 6.0%, respectively. Most of the suspected allergic reactions were non-immediate cutaneous events attributable to beta-lactam antibiotics and occurred in very young children. Thirty-nine of the 60 patients consulting for evaluation had a plausible clinical history and were recommended further investigation. DHs was diagnosed in three children only, based on positive responses in skin (n=1) and oral provocation (n=2) tests.

CONCLUSION

ADRs are frequently reported in children, and many children are classified as having a DAll. After complete evaluation, only a few of these reactions can be attributed to DHs and DAll. Most of the patients (94% in this study) could actually tolerate the initially suspected drug.

Oral challenges are needed in the diagnosis of beta-lactam hypersensitivity

BACKGROUND

beta-lactams continue to remain the most commonly involved drug family in allergic drug reactions. They are often essential and there is a cost-effective and favourable risk-benefit ratio for the exploration of all suspicions of beta-lactam allergy. A firm diagnosis is always based on skin tests and sometimes on provocation tests. Recommendations have been published by allergy societies and distinguished scientists but they are not always concordant and can lead to some confusion for the practicing allergologist. The situation has even worsened since the world wide withdrawal of these penicillin determinants and since the predominance of amoxicillin and cephalosporin prescriptions in most countries. OBJECTIVE - METHOD: In a recent article, it was stated that patients with a penicillin allergy history and negative skin tests to major and minor penicillin determinants are at a low risk of relapse (0-5%) when receiving a beta-lactam. In this paper, our Drug Allergy and Hypersensitivity Database, a cohort database, was used to demonstrate that this statement is false. Standardized European Network for Drug Allergy questionnaires, skin test and challenge procedures were followed.

RESULTS

One-thousand two-hundred and eighteen subjects, 69.8% of female, 51.7% of atopics, were included. 21.1% had a true beta-lactam allergy confirmed by skin tests (178, 69.3%) or by drug provocation (79, 30.7%). 17.4% of the patients with negative skin tests to major and minor penicillin determinants were positive for a beta-lactam.

CONCLUSION

In the diagnosis of beta-lactams allergy, if all skin tests are negative, skin tests with other determinants and provocation tests under strict surveillance are mandatory.

Human leukocyte antigens and drug hypersensitivity

PURPOSE OF REVIEW

The present article reviews the recent literature on the identification of human leukocyte antigen (HLA) alleles as major susceptible genes for drug hypersensitivity and discusses the clinical implications.

RECENT FINDINGS

Several recent studies have reported strong genetic associations between HLA alleles and susceptibility to drug hypersensitivity. The genetic associations can be drug specific, such as HLA-B*1502 being associated with carbamazepine-induced Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN), HLA-B*5701 with abacavir hypersensitivity and HLA-B*5801 with allopurinol-induced severe cutaneous adverse reactions. A genetic association can also be phenotype-specific, as B*1502 is associated solely with carbamazepine-SJS/TEN, and not with either maculopapular eruption or hypersensitivity syndrome. Furthermore, a genetic association can also be ethnicity specific; carbamazepine-SJS/TEN associated with B*1502 is seen in south-east Asians but not in whites, which may be explained by the different allele frequencies.

SUMMARY

The strong genetic association suggests a direct involvement of HLA in the pathogenesis of drug hypersensitivity when the HLA molecule presents an antigenic drug for T cell activation. The high sensitivity/specificity of some markers provides a plausible basis for developing tests to identify individuals at risk for drug hypersensitivity. Application of HLA-B*1502 genotyping as a screening tool before prescribing carbamazepine could be a valuable tool in preventing carbamazepine-induced SJS/TEN in south-east Asian countries.

Methods of evaluating immunotoxicity

Immunotoxicology is an important aspect of the safety evaluation of drugs and chemicals. Immunosuppression, (unspecific) immunostimulation, hypersensitivity and autoimmunity are the four types of immune-mediated adverse effects. However, the nonclinical assessment of immunotoxicity is at present often restricted to animal models and assays to predict unexpected immunosuppression. There is, however, no general consensus that a variety of assays can be considered depending on the compound to be tested. A major issue is whether histological examination of the thymus, spleen, lymphoid organs and Peyer's patches is a reliable predictor of immunosuppression or whether immune function should also be assessed. A T-dependent antibody response assay, either the plaque-forming cell assay or anti-keyhole limpet haemocyanin enzyme-linked immunosorbant assay, is recommended as a first-line assay. A variety of assays, including lymphocyte subset analysis, natural killer-cell activity, lymphocyte proliferation, delayed-type hypersensitivity, cytotoxic T-lymphocyte activity and macrophage/neutrophil function assays, can also be used. In certain circumstances, host resistance assays can be considered. With the exception of contact sensitisation, very few animal models and assays can reliably predict the potential for (unspecific) immunostimulation, hypersensitivity or autoimmunity. A major limitation of immunotoxicity risk assessment is the lack of human data. Immunological end points and clinical criteria to be included in clinical trials and epidemiological studies have to be carefully standardised and validated.

Adverse cutaneous drug eruptions and HIV: a clinician's global perspective

Adverse drug reactions (ADRs) are common and mostly avoidable. Some ADRs cannot as yet be predicted, but at-risk populations/patients and high-risk drugs are identifiable. HIV-infected patients are at risk of developing cutaneous ADRs, especially Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug hypersensitivity syndrome. Multiple factors of causation variably present in patients with HIV infection best explain the pathogenesis of these cutaneous ADRs. When no effective alternate therapy is available, drug rechallenge in HIV-infected patients can be attempted with little morbidity or mortality if done according to rationalized protocols.

Pharmacogenetics and the concept of individualized medicine

Adverse drug reaction in patients causes more than 2 million hospitalizations including 100,000 deaths per year in the United States. This adverse drug reaction could be due to multiple factors such as disease determinants, environmental and genetic factors. In order to improve the efficacy and safety and to understand the disposition and clinical consequences of drugs, two rapidly developing fields--pharmacogenetics (focus is on single genes) and pharmacogenomics (focus is on many genes)--have undertaken studies on the genetic personalization of drug response. This is because many drug responses appear to be genetically determined and the relationship between genotype and drug response may have a very valuable diagnostic value. Identification and characterization of a large number of genetic polymorphisms (biomarkers) in drug metabolizing enzymes and drug transporters in an ethnically diverse group of individuals may provide substantial knowledge about the mechanisms of inter-individual differences in drug response. However, progress in understanding complex diseases, its negative psychosocial consequences, violation of privacy or discrimination, associated cost and availability and its complexity (extensive geographic variations in genes) may become potential barriers in incorporating this pharmacogenetic data in risk assessment and treatment decisions. In addition, it requires increased enthusiasm and education in the clinical community and an understanding of pharmacogenetics itself by the lay public. Although individualized medications remain as a challenge for the future, the pharmacogenetic approach in drug development should be still continued. If it becomes a reality, it delivers benefits to improve public health and allow genetically subgroup diseases thereby avoiding adverse drug reactions (by knowing in advance who should be treated with what drug and how).