Successful readministration of trastuzumab after severe immune reactions in two breast cancer patients

Summary Trastuzumab is a standard treatment in breast cancer overexpressing Her2 oncogene. However, its administration carries the risk of severe immune adverse events which often lead to the discontinuation of trastuzumab. There is no clear guideline on how patients experiencing trastuzumab-related reaction should be rechallenged with the monoclonal antibody. Here, we present two case reports of patients who have presented severe anaphylactic reactions during trastuzumab infusion. Both of them have been successfully rechallenged in intensive care units with premedication, lower rate of infusion and vitals monitoring. Thereafter, trastuzumab could be continued without any serious adverse reaction. Given the positive impact of trastuzumab on patients’ survival, treatment rechallenge should be carefully considered in patients who presented anaphylactic reactions.