Complex Karyotype Predicts Outcome Better Than Monosomal Karyotype In Patients with MDS/Secondary Acute Leukemia Treated with Allogeneic Hematopoietic Stem Cell Transplantation (HSCT): a Retrospective Survey on Behalf of the Chronic Leukemia Working Party of the European Group for Blood and Marrow Transplantation (EBMT)
Authors: Brands-Nijenhuis Angelique .M. , van Gelder Michel , de Witte Theo M. , Schetelig Johannes , van Biezen Anja , Kroeger Nicolaus 
Published: October 2019

Abstract
Abstract 578

Introduction
Monosomal Karyotype (MK) has been shown to be associated with a very poor prognosis in AML patients. Last year at ASH, we presented data from the EBMT on patients diagnosed with MDS and chromosome 7 abnormalities, showing that MK predicts better than complex karyotype (CK) for a dismal outcome after allogeneic HSCT (abstract #293). We now performed a retrospective analysis on data from the registry in the complete cohort of patients with MDS and secondary AL (sAL) to determine the effect of MK on outcome after allogeneic HSCT.

Methods
A total of 1689 patients from 172 centres in 23 countries with diagnosis MDS or secondary acute leukemia (sAL) with known cytogenetic abnormalities (karyotype only) at diagnosis or later in the disease course were assessed. 1437 were included in the analysis; 226 were excluded because of insufficient data. Kaplan-Meier survival curves were used and log rank test to determine statistical significance.

Results
1041 patients were diagnosed with MDS and 396 with sAL. Median follow up for sAL patients was 7.5 months (range 0–253) and MDS 8.0 months (range 0–276). 201 patients fulfilled criteria for MK and 279 patients for complex karyotype (CK). MK outcome was worse than no MK: overall survival 32 months versus 97 months (p=0.002). CK outcome was worse than no CK: overall survival 26 months versus 100 months (p&lt;0.0001). No difference in outcome between MK and CK existed: overall survival of 32 months and 26 months respectively (p= 0.274).
There was considerable overlap between MK and CK (i.e. patients fulfilling criteria both for MK and CK). To see how we could further differentiate, we analyzed three subgroups: MK but not CK (43 patients; MK+CK−), no MK but CK (98 patients; MK−CK+) and MK and CK (150 patients; MK+CK+). The survival of patients in each of these groups was compared with the group having no MK and no CK (n=1050). Overall survival was not different for patients with MK+CK− (median 13 vs 19 months, p=0.983), but for patients with MK-CK+ or MK+CK+ a significant difference in survival was observed with a median of 8 months (p=0.008) and 7 months (p&lt; 0.0001) respectively. MK−CK+ and MK+CK+ did not differ statistically (p=0.42) from each other. See figure.
These results differ from the results presented at ASH last year. Since this cohort consists of patients with and without chromosome 7 abnormalities, we suspect that presence of this specific chromosomal aberration is the main reason for the observed difference. Multivariate analysis will be performed the coming months.

Conclusion
These results indicate that CK is a better predictor for poor outcome than MK after allogeneic HSCT in this cohort of MDS and sAL patients with and without chromosome 7 abnormalities.

Disclosures:
No relevant conflicts of interest to declare.