Clinical Utility of Basophil CD203c as a Biomarker for Predicting the Timing of Hypersensitivity Reaction in Carboplatin Rechallenge: Three Case Reports

PurposeDrug desensitization has been found to be an effective option for carboplatin rechallenge in patients at risk for severe hypersensitivity reaction. However, identifying such patients requires precise clinical tests. This study was performed to evaluate the clinical utility of basophil CD203c to predict the timing of carboplatin-induced severe hypersensitivity reaction.MethodsHere we report on 3 patients undergoing a carboplatin-desensitization protocol at Mie University Hospital. For all patients, ex vivo exposure to carboplatin resulted in increased levels of activated basophils in a previous occurrence of carboplatin-induced severe hypersensitivity reaction.FindingsBasophil activation test using carboplatin was returned to negative just before the first course of carboplatin-desensitization protocol in all patients, and they successfully received their first course of the protocol with no signs of anaphylaxis. However, for all of the patients, increased basophil activation was once again detected after subsequent readministration of carboplatin and grade 3 or 4 anaphylaxis developed. Basophil activation test coincided precisely with the timing of carboplatin-induced anaphylaxis in all patients.ImplicationsCD203c basophil activation testing might prove to be a reliable tool for risk stratification and clinical decision making for carboplatin desensitization in which severe hypersensitivity reaction is likely to occur.