Alloimmunisation rate of patients on Daratumumab: A retrospective cohort study of patients in England

Whilst small-scale studies on rates of alloimmunisation of patients on Daratumumab have been undertaken, no large-scale study has been performed to date on this cohort of patients.Patients with multiple myeloma (MM) who are relapsed or refractory to standard treatment are treated with the anti-CD38 therapeutic monoclonal antibody, Daratumumab. Due to the complexity of pre-transfusion compatibility testing, many MM patients in England are referred to Red Cell Immunohaematology (RCI) laboratories for investigation and provision of Red Blood Cell (RBC) components.Over a 4-month period, patients due to commence, or currently on anti-CD38 therapy were identified and flagged on the RCI Laboratory Information Management System (LIMS). Data was identified and extracted for further analysis. Interrogation of data was performed independently by two subject matter experts, with discrepancies resolved through further enquiry.Of 734 English MM patients, we report an alloimmunisation rate of 0.4% whilst on an anti-CD38 TMAb. This is in line with other smaller cohort studies.Given the low rate of RBC alloimmunisation, consideration should be given to revising the pre-transfusion testing regimen in this cohort. This may improve testing costs, turn-around times and evidence-based patient care.