Guidance for transfusion management in patients receiving magrolimab therapy (anti‐CD47 monoclonal antibody)

Magrolimab (Hu5F9‐G4) is a first‐in‐class anti‐CD47 IgG4 monoclonal antibody, with potential applications in several malignancies including myelodysplastic syndrome. CD47 blockade in malignancy has been shown to promote antitumour effects. However, the ubiquity of CD47 on red blood cells can result in interference in pretransfusion immunohaematology investigations and hinder timely provision of red blood cell units, with potential to mask clinically significant alloantibodies. We reviewed the literature for pretransfusion interference seen with magrolimab and methods to circumvent potential issues, and sought to provide clinical and laboratory recommendations for safe local transfusion practices. These recommendations are based on expert opinion and available literature, including the Victorian Senior Transfusion Scientist working group and professional societies and organisations (Australian & New Zealand Society of Blood Transfusion and Lifeblood representatives), to establish consensus recommendations. Interference in the ABO group and antibody screen can occur, and baseline immunohaematology testing prior to magrolimab therapy is critical. Antibody screening using an antihuman globulin reagent that does not detect human IgG4 subclass may distinguish magrolimab interference from an underlying alloantibody in patient plasma. Clear and consistent protocols for laboratories and close communication with clinicians are paramount to facilitate timely and safe transfusion support for patients receiving magrolimab therapy. As local transfusion laboratories gain experience with magrolimab, this will assist in our understanding and comfort in managing these patients.