Hypersensitivity Reactions to Rituximab: 53 Successful Desensitizations in 7 Patients with Severe, Near-Fatal Reactions

Rationale: Rituximab is a chimeric mouse-human monoclonal antibody with a paramount role in some hematological malignancies. Hypersensitivity reactions (HSRs) to rituximab are common; and vary from mild urticaria to severe, life-threatening events. While in most patients, the Boston 12-step desensitization procedure will suffice, patients who have endured severe reactions may warrant pre-medication prior to the desensitization protocol. We describe our experience with the modified protocol in patients who underwent severe, life-threatening reactions following previous rituximab administrations.   

Methods: A total of seven hematological patients were included. All had experienced severe anaphylactic or immunocytotoxic reactions during rituximab administration.  Four patients had suffered a cardiovascular collapse, of which one sustained a cardiac arrest and two required prolonged intensive care unit hospitalizations. The seven patients were treated with pharmacologic prophylaxis prior to a 12-step desensitization protocol. Prophylaxis included three doses of prednisone, high doses of H1 blockers, and an H2 blocker. Montelukast was added in two patients. We describe the patient demographics, the severity and characteristic of the initial HSRs and the outcomes of subsequent rituximab administration utilizing the modified protocol.  

Results: Fifty-three modified desensitization protocols were successfully completed (with a 100% success rate). Mild HSRs appeared in only three of the procedures. Six of the patients are currently in remission of their hematological disorder. 

Conclusions: A modified protocol including pharmacologic prophylaxis prior to the standard 12-step desensitization procedure is reliable and safe even among patients who had experienced near-fatal HSRs. This protocol should be considered in patients who mandate rituximab administration despite a severe previous reaction.