Successful desensitization for cytarabine-induced anaphylaxis: The first documented case report in Vietnam

The chemotherapeutic agent cytarabine is an uncommon cause of anaphylaxis. According to the World Allergy Organization, the diagnosis of anaphylaxis is primarily based on clinical symptoms, while biomarkers play a supporting role. However, in some cases, the underlying factors are complex and challenging to identify, especially in countries that lack the laboratory capacity to perform specialized tests. Drug desensitization – the temporary induction of tolerance to a sensitized drug – is the optimal approach when no alternative drug is available; however, desensitization is not always successful. Adjusting the desensitization protocol by extending the duration of each step or intensifying premedication drugs is the proposed solution to address this problem. To date, there have been few reports about cytarabine desensitization. We report the case of a 31-year-old male with acute myeloid leukemia (AML-M2) who developed severe anaphylaxis during his fourth course of high-dose cytarabine. An initial 13-step desensitization protocol failed at step 12. Consequently, a revised protocol was implemented, featuring intensified anaphylaxis premedication – including hydrocortisone, montelukast, and levocetirizine administered 3 days before and during the procedure. This modified approach successfully induced temporary tolerance, allowing the patient to complete the required 3,000 mg/day dose without further adverse reactions. This is the first reported case of successful cytarabine desensitization following anaphylaxis in Vietnam. Our findings highlight that anaphylaxis premedication is essential for the success of rapid desensitization protocols, especially in high-risk patients or after initial failure.