Optimized strategy to mitigate daratumumab interference in blood bank testing: Reducing cost and time

Drug interference with pretransfusion testing in patients with multiple myeloma (MM) treated with daratumumab (DARA) is well recognized. Current guidelines recommend that these patients should have a red blood cell (RBC) phenotype or genotype before DARA initiation; however, there are no other standards for pretransfusion testing. While prior publications report mitigation strategies and low RBC alloimmunization risk, they do not propose a cost-effective strategy for pretransfusion testing. This study aims to assess the RBC alloimmunization risk in patients treated with DARA and propose a cost-effective algorithm for pretransfusion testing.

This is a retrospective study of patients treated with DARA and receiving RBC transfusions over 9.4 years (October 1, 2015, to January 30, 2025). Demographic data; a complete serologic profile, including blood typing, antibody screen (Ab screen), and antibody identification (Ab ID); RBC phenotype/genotype; and crossmatch data were collected for each patient. The clinically significant antibody formation incidence was recorded pre- and post-DARA and compared with a control group, with statistical significance defined as P < .05. The mitigation strategy initially used for pretransfusion testing and its optimized version are described along with their cost.

Of the 850 patients with MM on DARA therapy who were identified, 172 (20%) received at least 1 RBC transfusion. Ab screens were performed on all patients pre- and post-DARA therapy. Following drug administration, all patients showed a panagglutinin, and no patients formed new clinically significant alloantibodies. The turnaround time (TAT) and cost significantly decreased when the pretransfusion strategy with optimizing pretransfusion strategy.

This is the most extensive study on patients treated with DARA and transfused, demonstrating no increased alloimmunization risk. DARA-related transfusion interference may be successfully mitigated by the novel strategy proposed here.