Fostamatinib, A Spleen Tyrosine Kinase (Syk) Inhibitor, For The Treatment Of Warm Antibody Autoimmune Hemolytic Anemia (Waiha): Final Results Of The Phase 2, Multicenter, Open-Label Study

Introduction. wAIHA is a rare and often serious disease in which red blood cells (RBCs) coated with autoantibodies bind to Fcγ receptor-bearing macrophages, triggering a spleen tyrosine kinase (SYK) dependent signaling pathway that leads to RBC phagocytosis. Fostamatinib is a potent SYK inhibitor administered orally that was approved by the US FDA for the treatment of chronic ITP in adults. A phase 2, multicenter, open-label study (the SOAR study; NCT02612558) evaluated the response to fostamatinib in adult patients with wAIHA. We report the final results of the initial 24-week treatment period and the extension period of the phase 2 study.