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GR, complete remission, PR, partial remission.

GR, complete remission, PR, partial remission.

paucity of available treatments for MDS, patients should be referred for appropriate clinical trials whenever possible.Low-intensity therapies, such as histone deacetylase inhibitors, farnesyl transferase inhibitors, and tyrosine kinase inhibitors, are being tested in advanced MDS and AML, but may be evaluated in lower risk MDS as well. In Chapter X, such novel approaches to treating MDS will be discussed in detail.

HIGH-INTENSITY THERAPY: CHEMOTHERAPY OR STEM CELL TRANSPLANTATION

Intensive chemotherapy treatment for MDS has generally produced complete remission rates of 40-50%, which is lower than the response rates seen in the younger patients with de novo AML. Furthermore, remission durations are generally brief (5-15 months), and given the treatment-related mortality of —25-50% and the time required to recover to baseline function for survivors of such therapy, the use of AML-like therapies has been limited. Although some patients have achieved complete hematologic and cytogenetic remissions, no survival benefit has yet been shown for intensive chemotherapy. Several new combinations have been studied for advanced MDS, which include the topoisomerase I inhibitor topotecan.59 60 These combinations are unlikely to produce a significant improvement in survival unless followed by allo-geneic stem cell transplants. In general, these treatments should be reserved for higher risk patients enrolled in clinical trials, given the uncertain risk-benefit ratio.

Allogeneic stem cell transplant is the only potentially curable treatment for MDS. Although it appears that the associated short-term and long-term risks of transplant are generally acceptable for high-risk MDS patients, the optimal timing for transplanting patients

(1) anemia: Consider rHuEPO +/— G-CSF, 5-azacytidine, ATG, (ce-5013 if FDA-approved), or Thalidomide

(in a clinical trial);

(2) severe neutropenia or thrombocytopenia: Consider stem cell transplantation early. Alternatively (or pretransplant), consider 5-azacytidine (or decitabine, if available), ATG, or AML-like regimens;

(3) points 1 or 2 and/or increased blasts (at risk for leukemic progression): Consider Stem cell transplant, 5-azacytidine (or possibly decitabine).

Considerations for stem cell transplant candidates: patients with fewest precent blasts do best; not known if pre-stem cell transplant treatment is of benefit.

with low-risk disease is not established. Furthermore, it is not clear how pretransplant therapies or the degree of pretransplant cytoreduction impacts on the disease-free survival of MDS patients.

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