Dose reductions and delays: limitations of myelosuppressive chemotherapy.

Thrombocytopenia occurs at various grades of severity in patients with nonmyeloid malignancies undergoing chemotherapy with myelosuppressive agents. Frequently, it is the major dose-limiting hematologic toxicity, especially in the treatment of potentially curable malignancies such as leukemia, lymphomas, and pediatric cancers. This is becoming increasingly important given the recent trend toward the use of dose-intensive combination chemotherapy regimens facilitated by supportive hematopoietic colony-stimulating factors to prevent chemotherapy-induced febrile neutropenia. The standard preventive measure against chemotherapy-induced depression of platelets in subsequent treatment cycles has been dose reduction and/or dose delay. However, follow-up data from studies in various populations of patients with cancer suggest a correlation between delivery of lower than intended doses and poor outcomes, including reduced disease-free periods and overall survival. Other consequences of thrombocytopenia include the need for platelet transfusions and subsequent exposure to the risk of numerous complications, including bacterial and viral infections; febrile, nonhemolytic transfusion reactions; and transfusion-induced immunosuppression. Furthermore, a large proportion of multitransfused patients become refractory to subsequent infusions. Refractoriness to platelet transfusions is quickly becoming more prominent. The availability of a platelet growth factor--recombinant human interleukin-11(rhIL-11, also known as oprelvekin [Neumega])--provides an effective means of preventing chemotherapy-induced thrombocytopenia and accelerating platelet recovery, thereby facilitating the administration of full doses of chemotherapy during subsequent cycles and avoiding the need for rescue with platelet transfusions.