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.

Cold reacting anti-M causing delayed hemolytic disease of the newborn.

BACKGROUND: Hemolytic disease of the fetus and newborn (HDFN) is due to passively transferred maternal antibodies directed against fetal red blood cell (RBC) antigens and can lead to severe morbidity and mortality. Anti-M is usually a naturally occurring antibody of low clinical significance, although occasionally severe cases of HDFN are seen. CASE REPORTS: Two M+ sisters are presented, each developing hemolysis during the first 2 weeks of life due to maternal anti-M, resulting in severe anemia and requiring blood transfusion. RBC agglutination was observed in peripheral blood samples of both infants at room temperature with dissociation at 37°C. Maternal anti-M detected by column indirect agglutination technique, was of low titer (1:16) and demonstrated low thermal amplitude, reacting in saline at 4°C but was not detectable in saline at 37°C. CONCLUSIONS: Anti-M of low thermal amplitude may cause hemolytic disease of the newborn with laboratory features resembling cold agglutinin disease.