Reduced intensity conditioning equals myeloablation for MDS survival
medwireNews: A reduced-intensity conditioning (RIC) regimen offers at least equivalent 2-year relapse-free and overall survival to a myeloablative conditioning (MAC) regimen before allogeneic transplantation in patients with myelodysplastic syndrome (MDS), RICMAC researchers report.
The randomized, multicenter, phase III study compared a RIC regimen consisting of busulfan (8 mg/kg orally or 6.4 mg/kg intravenously) and fludarabine (150 mg/m2) with a MAC regimen consisting of busulfan (16 mg/kg orally or 12.8 mg/kg intravenously) and cyclophosphamide (120 mg/kg) in 129 patients with MDS or secondary acute myeloid leukemia and less than 20% blast cells.
As reported in the Journal of Clinical Oncology, there were no significant differences between RIC and MAC in the cumulative incidence of acute graft-versus-host disease II–IV (32.3 vs 37.5%) or chronic graft-versus-host disease at 2 years (61.6 vs 64.7%).
There were also no differences in nonrelapse mortality after 1 year, at 16.9% after RIC and 25.3% after MAC, and relapse at 2 years, at 17.0% and 14.8%, respectively.
This gave 2-year relapse-free survival and overall survival rates of 62.4% and 76.3%, respectively, after RIC, and 58.3% and 63.2%, respectively, after MAC, again with no significant differences between the two conditioning regimens.
However, multivariate analysis showed that overall survival was significantly better with RIC than with MAC, at a hazard ratio 0.41.
The researchers say this “might be a result of lower mortality after relapse” because six of nine patients who experienced relapse in the MAC arm died, compared with only two of 11 in the RIC arm.
Nicolaus Kröger (University Medical Center Hamburg-Eppendorf, Germany) and co-authors conclude that their findings indicate that RIC “can be offered as an alternative to a myeloablative regimen” in patients with MDS.
However, in an editorial that accompanies the research, Michael Pulsipher, (Children’s Hospital Los Angeles, California, USA) questions whether “RIC [is] worth the gamble,” particularly in “patients with MDS who are well and who are candidates for MAC approaches.”
He points out that the MAC regimen used in the current study “has been shown to be inferior to myeloablative busulfan/fludarabine because of higher [transplant-related mortality].”
Therefore “[m]ore data from the use of the safer MAC approach of higher-dose busulfan/ fludarabine compared with busulfan/fludarabine RIC or compared with fludarabine/melphalan RIC are needed to make a more compelling argument for use of RIC for MDS, especially for advanced MDS,” he concludes.
By Laura Cowen
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