Canada’s First Joint Oncology-Allergy Clinic: Successful Desensitization to Trastuzumab Following Severe Anaphylactic Reaction in Which Epinephrine Was Inappropriately Withheld

Background: Recognition of anaphylaxis and differentiation from other infusion reactions in an oncology setting is imperative; epinephrine is the recommended treatment for anaphylaxis and should be administered immediately to patients in whom anaphylaxis is suspected. Trastuzumab has a potentially tremendous oncological benefit, and when hypersensitivity reactions occur, rechallenge with desensitization protocols has become more common. Oncology presents a unique situation in which repeat drug exposure after a serious adverse reaction is often warranted due to the mortality risk of untreated cancer—allergists can assist with both symptom assessment and risk mitigation. Case presentation: This case showcases successful desensitization in a 43-year-old female with locally advanced HER2-positive breast cancer following a severe anaphylactic reaction to trastuzumab, in which epinephrine was not administered. We report the establishment of the Medical Oncology and Allergy Clinic: Canada’s first multidisciplinary clinic aimed at expediting the assessment and management of oncology patients with adverse drug reactions (including chemotherapy, contrast media, antimicrobials) and those with