Treatment for Myelodysplastic Syndromes
One decision model found that the likelihood of responding to growth factors was higher in patients with a low serum erythropoietin level (defined as a level <500/µL) and low transfusion needs (defined as <2 units of packed red blood cells every month), but growth factors were rarely effective in patients with a high erythropoietin level and high transfusion needs. Some patients with poor response to erythropoietin alone may have improved response with the addition of low doses of granulocyte colony-stimulating factor (G-CSF) (0.5–1.0 µg/kg/day).[9,10,11] Rates of response to the combination treatment vary with classification, with responses more likely in patients with refractory anemia and ring sideroblasts (RARS) and less likely in patients with excess blasts. Patients with RARS are unlikely to respond to erythropoietin alone.
The availability of the oral iron-chelating agent deferasirox has led to its widespread use in MDS patients. While some consensus panels advocate prophylactic iron chelation in patients with ongoing transfusion needs and substantial transfusion history, the impact of iron chelation on survival and disease progression is unknown.
Lower-risk patients (conventionally defined as International Prognostic Scoring System (IPSS) low-risk and intermediate-1–risk groups) who have failed to respond or have ceased responding to ESAs may be treated with one of several disease-modifying agents. The impact of this practice on survival in lower-risk patients is unknown. Whether these drugs should be used following an ESA failure or as up-front therapy has never been determined. In contrast, in higher-risk patients, azacitidine has been shown to improve survival. (Refer to the DNA methyltransferase inhibitors section of this summary for more information.)
Lenalidomide is FDA-approved for the treatment of lower-risk, transfusion-dependent MDS patients who harbor a del(5q) cytogenic abnormality. In a phase II registration study of 148 transfusion-dependent low-risk and intermediate-1–risk patients with del(5q) chromosomal abnormalities (alone, or associated with other abnormalities), lenalidomide induced transfusion independence in 67%, with a median time to response of 4 to 5 weeks. The median duration of transfusion independence had not been reached after a median of 104 weeks of follow-up. Of 62 evaluable patients, 38 patients developed complete cytogenetic remission.