Sequential vs Myeloablative vs Reduced Intensity Conditioning for Patients with Myelodysplastic Syndromes with an excess of blasts at time of allogeneic haematopoietic cell transplantation: A Retrospective Study by the Chronic Malignancies Working Party of the EBMT

Abstract

<title>Abstract</title> <p>The optimal conditioning for patients with higher risk MDS receiving potentially curative allogeneic haematopoietic stem cell transplant(allo-HCT) remains to be defined. This is particularly the case for patients with excess of blasts at time of allo-HCT. Sequential(Seq) conditioning, whereby chemotherapy is followed rapidly by transplant conditioning, offers an opportunity to decrease disease burden, potentially improving outcomes allo-HCT outcomes. Herein we present the only analysis comparing Seq to myeloablative(MAC) and reduced intensity conditioning(RIC) specifically focussed on MDS patients with excess of blasts at allo-HCT. 303 patients were identified in the EBMT registry, receiving RIC(n=158,) Seq(n=105,), and MAC(n=40, ). Median follow-up was 67.2 months and median age at allo-HCT was 59.5 years(IQR 53.5 - 65.6). For the entire cohort, 3yr overall survival(OS) was 50%(95% CI45-56%) and relapse free survival(RFS) 45%(95%CI 40-51%). No differences in outcomes were observed per protocol with respect to OS and RFS. On multivariable analysis, lower performance status, worse IPSS-R cytogenetics, sibling donor (compared to 8/8 MUD) and &gt;20% blasts at allo-HCT were associated with worse outcomes. In conclusion, the Seq protocol did little to influence the outcome in this high-risk group of patients, with outcomes mostly determined by baseline disease risk and patient characteristics such as performance status.</p>