Risk of Anaphylaxis with Repeated Courses of Rasburicase: A Research on Adverse Drug Events and Reports (RADAR) Project

Background Rasburicase, a recombinant urate oxidase, is used to rapidly metabolize uric acid in patients with hyperuricaemia. Rasburicase is an immunogenic therapeutic protein, which has been shown to elicit antibody response in 64% of healthy volunteers within 1-6 weeks after the initial course, with persistent antibodies for over 1 year. Drug labelling indicates that anaphylaxis rarely occurs (in <1% of patients) after a single course of therapy with rasburicase, but there are no data available on the incidence of anaphylaxis in patients receiving a subsequent rasburicase course. Objective The objective of this study was to determine the incidence of anaphylaxis after multiple treatment courses of rasburicase. Methods A retrospective chart review was performed on 97 consecutively treated patients who received repeated courses of rasburicase for hyperuricaemia. Results None of the 97 patients who were reviewed experienced anaphylaxis during the first rasburicase course; however, six patients (6.2%) experienced anaphylaxis during a subsequent rasburicase treatment course (p = 0.03). Conclusion Anaphylaxis after a second course of rasburicase appears to occur more frequently than described in the US Food and Drug Administration-approved package insert for initial treatment courses. Given the serious nature of anaphylactic events, caution is advised when administering repeated courses of rasburicase.