Practical Advances in Drug Hypersensitivity

Abstract

With the increase in new and better medications to treat cancer, chronic inflammatory diseases, and infections in the 21st century, a parallel increase in drug allergy and hypersensitivity has been seen. Patients are treated with repeated and multiple courses of sensitizing medications and with new targeted therapies that include small molecules and mAbs with immunogenic and allergenic capacity. Drug reactions prevent patients from receiving first-line therapy, and health care providers have few guidelines on how to diagnose and address these reactions, some of which can be life threatening. Identifying patients with a drug allergy protects them from reexposure to culprit medications and permits access to desensitization procedures when needed. Identifying patients who have lost their allergenic sensitivity helps avoid second-line therapies, increased costs, and resources utilization. Multiple studies have provided clear evidence that more than 90% of patients with a history of penicillin allergy are negative on skin testing and do not react during challenge, or during further courses of penicillin, but standardized US Food andDrug Administration approved reagents are lacking for the diagnosis of allergy to themajority of antibiotics and other drugs. Central to the evaluation of patients with drug hypersensitivity is the understanding of the pathophysiology of the reactions. For example, an increase in serum tryptase levels during the acute symptoms of anaphylaxis provides evidence of mast cell and/or basophil participation through IgE or non-IgE mechanisms. This issue of JACI: In Practice is devoted to advances and further understanding of the epidemiology of drug hypersensitivity and its diagnosis and treatment for the key central mechanisms of drug hypersensitivity: IgE and/or mast cell sensitization, HLA specificity, and viral reactivation. In this issue of the journal, Banerji et al start to unravel the epidemiology of drug-induced hypersensitivity by identifying 716 patients who presented with drug-induced anaphylaxis in a large emergency department database by using International Classification of Diseases, Ninth Edition codes. The majority of patients (71%)were female patients, only 8% received epinephrine, 23%of the hospitalized patients presented cardiovascular failure, and only