Opportunities for the use of thrombopoietic growth factors

Highly lineage specific thrombopoietic factors are now available which can produce substantial increments in platelet counts and attenuate the severity of therapy induced thrombocytopenia in preclinical models and early trials in patients. These striking findings are not equivalent to proving clinical benefit to patients, however, and studies are now in progress in a variety of clinical settings. Methodologic issues which could influence the interpretation of studies using thrombopoietin to mitigate thrombocytopenia in patients treated for acute myeloid leukemia and following stem cell transplantation are discussed. Studies in thrombocytopenic patients with myelodysplasia, aplastic anemia, immune thrombocytopenic purpura, as well as selected platelet and stem cell donors, are also of interest. It is unclear, however, whether patients with impaired marrow function can benefit from further exogenous stimulation, and side effects must be very carefully monitored in studies with normal donors.