The myelodysplastic syndromes: a personal recollection of four decades of classification and prognostic scoring systems

Myeloblasts transition to megakaryoblastic immunophenotypes over time in some patients with myelodysplastic syndromes

OBJECTIVES

In myelodysplastic syndromes (MDS), neoplastic myeloblast (CD34+CD13+CD33+ cells) numbers often increase over time, leading to secondary acute myeloid leukemia (AML). In recent studies, blasts in some MDS patients have been found to express a megakaryocyte-lineage molecule, CD41, and such patients show extremely poor prognosis. This is the first study to evaluate whether myeloblasts transition to CD41+ blasts over time and to investigate the detailed immunophenotypic features of CD41+ blasts in MDS.

METHODS

We performed a retrospective cohort study, in which time-dependent changes in blast immunophenotypes were analyzed using multidimensional flow cytometry (MDF) in 74 patients with MDS and AML (which progressed from MDS).

RESULTS

CD41+ blasts (at least 20% of CD34+ blasts expressing CD41) were detected in 12 patients. In five of these 12 patients, blasts were CD41+ from the first MDF analysis. In the other seven patients, myeloblasts (CD34+CD33+CD41- cells) transitioned to megakaryoblasts (CD34+CD41+ cells) over time, which was often accompanied by disease progression (including leukemic transformation). These CD41+ patients were more frequently observed among patients with monosomal and complex karyotypes. CD41+ blasts were negative for the erythroid antigen, CD235a, and positive for CD33 in all cases, but CD33 expression levels were lower in three cases when compared with CD34+CD41- blasts. Among the five CD41+ patients who underwent extensive immunophenotyping, CD41+ blasts all expressed CD61, but two cases had reduced CD42b expression, three had reduced/absent CD13 expression, and three also expressed CD7.

CONCLUSIONS

Myeloblasts become megakaryoblastic over time in some MDS patients, and examining the megakaryocyte lineage (not only as a diagnostic work-up but also as follow-up) is needed to detect CD41+ MDS. The immunophenotypic features revealed in this study may have diagnostic relevance for CD41+ MDS patients.

Can bone marrow cellularity help in predicting prognosis in myelodysplastic syndromes?

OBJECTIVES

To ascertain the relevance of bone marrow cellularity (BMC) to the interpretation of blast percentage (blast%) in MDS prognostication.

METHODS

We compared survival prediction based on blast% adjusted to different levels of cellularity, compared to the survival based on the original IPSS-R blast% grouping.

RESULTS

We analyzed 355 consecutive MDS patients. Cellularity, in and of itself or its interaction with blast%, was not associated with overall survival (OS). In a small subset of patients with a hypercellular marrow (15%; n = 26), dismal prognosis was observed at lower levels of blast%. For these cases OS was similar to higher IPSS-R blast groups. For example, within the Intermediate group (blast% 5%-10%), those with a hypercellular marrow and >6% blasts had an OS of 10 m similar to 16 m in the High (blast% 10%-19%) blast group. These changes did not translate into a significant improvement in overall prognostic power of a cellularity-adjusted IPSS-R (C index 0.71 vs. 0.70).

CONCLUSION

Adjusting blast% to cellularity did not improve prognostication. However, within IPSS-R-defined blast groups, a small subset of patients with relatively higher blast% and hypercellularity may have a worse prognosis than expected.

There's risk, and then there's risk: The latest clinical prognostic risk stratification models in myelodysplastic syndromes

Myelodysplastic syndromes (MDS) include a diverse group of clonal hematopoietic disorders characterized by progressive cytopenias and propensity for leukemic progression. The biologic heterogeneity that underlies MDS translates clinically in wide variations of clinical outcomes. Several prognostic schemes were developed to predict the natural course of MDS, counsel patients, and allow evidence-based, risk-adaptive implementation of therapeutic strategies. The prognostic schemes divide patients into subgroups with similar prognosis, but the extent to which the prognostic prediction applies to any individual patient is more variable. None of these instruments was designed to predict the clinical benefit in relation to any specific MDS therapy. The prognostic impact of molecular mutations is being more recognized and attempts at incorporating it into the current prognostic schemes are ongoing.