Hematopoietic growth factors in the pathogenesis and for the treatment of aplastic anemia.

The production and release of hematopoietic growth factors from bone marrow stromas established in vitro from patients with aplastic anemia is normal or increased. Addition of hematopoietic growth factors to aplastic anemia bone marrow cells results in only modest increases in colony growth, with the exception of granulocyte colony-stimulating factor (G-CSF), which corrects their impaired cloning efficiency to normal. Most clinical data on the use of hematopoietic growth factors in aplastic anemia have derived from uncontrolled and small single-arm studies or case reports. Sustained trilineage hematologic responses have not been observed when hematopoietic growth factors have been used alone or in combination. Serious side effects have been reported for most of the hematopoietic growth factors in patients with aplastic anemia, with the exception of G-CSF. There is a major concern that they may further increase the risk of clonal disorders such as myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Hematopoietic growth factors should not be used alone in newly diagnosed patients as specific treatment for aplastic anemia, and their use in combination with immunosuppressive therapy should be confined to multicenter, prospective randomized studies.