Megakaryocytic growth factors: is there a new approach for management of thrombocytopenia in patients with malignancies?

C-mpl ligand acts primarily as a lineage-specific hematopoietic growth fact or by promoting proliferation of megakaryocyte precursors and their differe ntiation into megakaryocytes and platelets. In addition to the ability of c -mpl ligand to support megakaryocytic development from CD34(+) precursor ce lls, several lines of evidence also point to a stimulatory effect on hemato poietic stem cells. When recombinant thrombopoietin or pegylated megakaryoc yte growth and development factor is administered to normal animals or huma ns, there is a dose-dependent increase in the platelet count When administe red following chemotherapy in animal models or humans, c-mpl ligands reduce the duration and sometimes the degree of thrombocytopenia. The issue of wh ether clinically relevant thrombocytopenia can be ameliorated has so far be en more difficult to resolve. Because severe thrombocytopenia is not common ly seen with standard chemotherapy regimens, clinical studies examining c-m pl ligands for their ability to ameliorate chemotherapy-induced thrombocyto penia will focus on treatment of acute leukemias and bone marrow transplant ation. The potential utility of c-mpl ligands for treatment of myelodysplas tic syndromes, aplastic anemias, or in HIV infection, will have to be evalu ated in the future. Possibly the greatest potential of thrombopopietic grow th factors in the near future may be In transfusion medicine, to collect an d to store platelets from healthy donors or in autologous settings.