Efficacy and Safety of Eltrombopag Combined with Cyclosporine As First-Line Therapy in Adults with Severe Acquired Aplastic Anemia: Results of the Interventional Phase 2 Single-Arm Soar Study

Background: Severe aplastic anemia (SAA) is a rare bone marrow failure disorder associated with significant morbidity and mortality. SAA is characterized by severe pancytopenia and a hypocellular (<25%) bone marrow. The standard of care treatment is hemopoietic stem cell transplant or immunosuppressive therapy (IST) for patients (pts) who are ineligible for transplant. IST usually comprises an antithymocyte globulin (ATG) derived from horse or rabbit, and cyclosporine A (CsA). Although IST can be an effective treatment, individual intolerance, insufficient response, relapse, and clonal evolution remain significant limitations. The lack of global availability of the more effective horse ATG also leaves many pts with limited treatment options and poorer outcomes. In addition, pts with SAA often require transfusions which can be burdensome and negatively impact their quality of life. Eltrombopag (ETB) is indicated for use in pts with SAA who have had an insufficient response to IST (FDA PI, 2014) or are refractory to IST (EMA SmPC, 2015). More recently in the USA, ETB may also be used in combination with IST as first-line (1L) treatment (FDA PI, 2018).