Introduction : Etoposide phosphate is a chemotherapeutic agent used to treat various malignant neoplasms. Hypersensitivity reactions may occur with its use, and in rare cases, an anaphylactic reaction can manifest. Available options for patients experiencing hypersensitivity reactions include premedication, changing treatment, or undergoing desensitization. Various pediatric desensitization protocols have been described, ranging from six to fifteen steps, while published adult cases are rare.

Case Report : We report the case of a 61-year-old woman with small-cell lung cancer and brain metastases. In November 2019, she underwent the second cycle of cisplatin and etoposide phosphate treatment. While receiving etoposide phosphate, she experienced dyspnea and suffered a cardiorespiratory arrest, leading to cardiopulmonary resuscitation and subsequent admission to the Intensive Care Unit. Her acute tryptase levels were notably elevated at 18 µg/L (compared to a baseline tryptase level of 6,6 µg/L) during the reaction.

Case Management : We implemented a 16-step desensitization protocol (without premedication) under close monitoring in an intermediate care unit. The protocol was successfully executed over three cycles until tumor progression mandated a modification in systemic treatment.

Discussion : To our knowledge, this is the first documented case of successful desensitization to etoposide phosphate in a patient who experienced cardiac arrest during a hypersensitivity reaction. Although protocols of varying lengths have been published, we emphasize the importance of individualizing each protocol to fit the severity of the reaction and the resources and experience of each unit.