Drug Desensitization Update: Key Concepts and Mechanisms

Purpose of Review Drug allergy is a worldwide healthcare problem, which prevents the use of first-line therapies and associates with increased morbidity and costs. The availability of new drugs, including biologicals, the extended use of old and new drugs, and the increased longevity of patients have favored sensitization and promoted the appearance of new phenotypes of drug allergy. While penicillin anaphylaxis was the first drug allergy described over 70 years ago, in the last 20 years patients with chemotherapy drugs and targeted therapies reactions have increased around the world. Recent Findings Drug-allergic patients are a disadvantaged population which has been addressed with avoidance of culprit drugs, but alternative therapies are not universally available, may be more costly, and may not provide similar therapeutic value. Drug desensitization was initiated to allow patients to be re-exposed safely to drugs which they had reacted. Summary Drug desensitization is a novel immunotherapy modality, delivered through multi-step protocols, which takes advantage of immune cells inhibitory mechanisms and addresses acute and delayed reactions. Its use has been expanding in the last 10 years due to unprecedented safety and efficacy. We describe here the mechanisms and principles of drug desensitization, which are applicable to all drug classes and to selected classical and new drug allergy phenotypes.