Response: Decitabine response with chromosome 7 abnormality in MDS, and decitabine optimal schedule

The observation of Rüter et al regarding the favorable response of patients with myelodysplastic syndrome (MDS) and chromosome 7 abnormalities to decitabine is interesting. We had previously analyzed the prognostic factors associated with decitabine therapy in our patients with higher risk MDS.¹  We did not find an association between pretreatment cytogenetic abnormalities and response, but found, by multivariate analysis, that the presence of chromosome 5 or 7 abnormalities was associated with poor survival.¹  Since this study classified the cytogenetic abnormalities slightly differently and correlated cytogenetic studies with complete cytogenetic response, we reanalyzed the data as reported by Ruter et al. This is summarized in Table 1. We could not confirm the positive effect of the presence of chromosome 7 abnormality with cytogenetic response on decitabine therapy. This may be due to differences in the study groups, the decitabine dose schedules, or the small number of patients involved in each of the 2 analyses.

We agree with Dr Giagounidis' comments. The Bayesian randomization design allows for studies with smaller numbers of patients, but can be associated with higher rates of false-positive and false-negative results, depending on the operating characteristics of the design. In our study, we can firmly conclude that the decitabine 10-day intravenous schedule is unlikely to be more active, is definitely more cumbersome, and is likely associated with more toxicities.²  However, as stated in our discussion, the decitabine 5-day subcutaneous schedule may still be as effective as the decitabine 5-day intravenous schedule, and would offer an alternative delivery route. The concluding statement of Dr Giagounidis' letter sums it up well: a comparison of the decitabine (100 mg/m² per course) 5-day intravenous versus 5-day subcutaneous schedule is needed but will require a larger comparative trial.