Management of Myelosuppression
Leukemia Insights - Fall 2008
During the course of treatment with imatinib and other tyrosine kinase inhibitors, 30% to 50% of patients develop grade 3 or 4 anemia, thrombocytopenia or neutropenia. Cytopenias most frequently occur during the first 2 to 3 months of therapy and in many instances they do not recur. This early myelosuppression is managed with a temporary treatment interruption if there is grade 3 or greater neutropenia (absolute neutrophil count <1 x 109/L) or thrombocytopenia (platelets <50 x 109/L). Upon recovery, the tyrosine kinase is restarted at the same dose if counts recover within 2 weeks or at a lower dose if recovery takes more than 2 weeks.10 For the occasional patient with prolonged and recurrent grade 3 or higher myelosuppression, hematopoietic growth factors have been used. Filgrastim (G-CSF) has been reported to improve the neutropenia, allowing uninterrupted therapy with imatinib, and frequently improving response to therapy.11 Erythropoietin and darbepoetin have also been reported to improve anemia associated with tyrosine kinase therapy but the impact on survival is uncertain.12 These are all investigational uses of these growth factors.