A 24-year-old man from Ecuador presents to your clinic with dyspnea on exertion, bruising, and petechiae. He is noted to be pancytopenic with ANC 430, hemoglobin 7.4 g/dL (reticulocyte count 0.9%), and platelets 18 000. His BM biopsy is hypocellular for age. Ultimately, he is diagnosed with severe aplastic anemia. He is the only child of 2 South American parents without any matches in the unrelated donor registry, including cord blood. He is red cell- and platelet transfusion-dependent. He has been recommended therapy with antithymocyte globulin and cyclosporine but declined it. He seeks recommendations about new alternatives to this regimen to improve his chance of response.