D1.233 - Pembrolizumab IgE mediated drug hypersensitivity reaction and successful desensitisation
Case report
Introduction: Pembrolizumab is a humanized monoclonal IgG4 antibody that targets programmed cell death protein 1 (PD1).It has been approved for the treatment of several types of cancer including non small cell lung carcinoma (NSCLC). Pembrolizumab can be used either as monotherapy or as a combination treatment with chemotherapy. Hypersensitivity reactions are rare. There are several reports of severe cutaneous adverse reactions (SCARS) mainly Stevens-Johnson and TEN. Immediate IgE mediated immune reactions are rare.
Purpose: We report a case of an IgE mediated hypersensitivity reaction to pembrolizumab and successful desensitization.
Background: A 64 year old woman was diagnosed with NSCLC in May 2023.She started a combination treatment of chemotherapy (Carboplatin-Pemetrexed) and immunotherapy (pembrolizumab) on 22nd of June 2023. After completing three cycles she continued immunotherapy with pembrolizumab as a maintenance therapy without presenting any complications except from the last two cycles. In the penultimate cycle, fifteen minutes after the end of the infusion, the patient reported a sense of pruritus in the palms and erythema but she did not receive any treatment. Ten minutes later she developed urticarial rash on the forearms and the trunk and hoarse voice so she was treated with per os antihistamines and corticosteroids. 21 days later she returned for the next cycle of treatment. After the end of the infusion, the patient reported blurred vision, dizziness, chest tightness and difficulty in breathing. She received intravenous treatment and the symptoms resolved in about 15 minutes.
Methods: The patient was referred to our Allergy Department for evaluation. One month after the reaction Skin Prick Tests (SPTs) and Intradermal Tests (IDs) were performed to pembrolizumab. Both SPTs dilutions (2.5 mg/ml and 25mg/ml) were negative. Then we proceeded with ID tests which came out positive in the lowest dilution 0.025mg/ml (control negative).Since pembrolizumab treatment was vital for the patient’s health it was decided to continue with desensitization procedure using a protocol of 3 bags and 14 steps. (Table 1). The patient managed to receive 6 cycles of desensitisation successfully.
Conclusion: Immediate IgE mediated hypesensitivity reactions to pembrolizumab are rare and paradoxically they happen after the patient has already received the medication many times without complications. However, even in these situations, the patients can continue their treatment with safety via desensitization.
