Transplants in Myelodysplastic Syndromes

Pretreatment CD34+/CD38- Cell Burden as Prognostic Factor in Myelodysplastic Syndrome Patients Receiving Allogeneic Stem Cell Transplantation

Myelodysplastic syndrome (MDS) is a highly heterogeneous clonal hematopoietic disorder. Allogeneic hematopoietic stem cell transplantation (HSCT) remains the only curative treatment and is of particular interest in patients at high risk for progression to acute myeloid leukemia (AML). In MDS, CD34⁺/CD38^- cells possess MDS stem cell potential, and secondary AML (sAML) clones originate from the MDS disease stage. However, the prognostic impact of the pretreatment stem cell population burden in MDS remains unknown. We retrospectively analyzed the prognostic impact of the pretreatment CD34⁺/CD38^- cell burden in 124 MDS patients who received allogeneic HSCT at our institution. A high pretreatment bone marrow CD34⁺/CD38^- cell burden (≥1%) was associated with worse genetic risk and a higher incidence of blast excess. Patients with a high CD34⁺/CD38^- cell burden had a significantly higher cumulative incidence of MDS relapse, a higher cumulative incidence of secondary AML, and a trend for shorter overall survival after allogeneic HSCT. In multivariable analyses this prognostic impact was shown to be independent of other clinical and cytogenetic risk factors in MDS. Patients suffering MDS relapse or progression to AML also had a higher pre-treatment CD34⁺/CD38^- cell burden as a continuous variable. The observed prognostic impact is likely mediated by MDS stem cells within the CD34⁺/CD38^- cell population initiating MDS relapse or progression to AML. New therapeutic strategies targeting MDS stem cells might improve outcomes.

Myelodysplastic syndromes and myelodysplastic/myeloproliferative neoplasms: an update on risk stratification, molecular genetics, and therapeutic approaches including allogeneic hematopoietic stem cell transplantation

Myelodysplastic syndromes are a heterogeneous group of clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis, peripheral cytopenias, and a variable propensity for leukemic transformation. In recent years there has been an explosion of information on the molecular genetic changes underlying these disorders. This information has substantial prognostic implications, and the influence on therapeutic approaches and the treatment of patients is evolving. Allogeneic hematopoietic stem cell transplantation (alloSCT) is the only known cure for these diseases, but appropriate patient selection is of utmost importance from a risk-benefit perspective. This review focuses on the factors influencing risk stratification in MDS and optimal choice of front-line therapy in the current era, including the interplay of clinical factors and molecular genetic factors, and factors that determine eligibility for alloSCT. The myelodysplastic/myeloproliferative diseases also will be discussed, including the increasing effort to understand the molecular genetics and natural history of these disorders and treatment approaches.