Impact of antithymocyte globulin (ATG)-containing conditioning regimens on patients undergoing allogeneic stem cell transplantation (allo-CST) for poor risk cytogenetic IPSS myelodysplastic syndrome (PRC-MDS): A report from the French Society of Stem Cell Transplantation and Cell Therapy (SFGM-TC).

Abstract

6542 Background: Due to a risk of relapse of underlying disease in patients with PRC-MDS, the use of ATG, incorporated within the conditioning regimen prior to allo-SCT, is still controversial. Methods: Inclusion criteria included patients aged over 18 (n=101) who received allo-SCT transplanted between 1999 and 2009 from either a sibling (n=68) or HLA-allele-MUD (10/10) (n=33) for PRC-MDS. HLA matching was double-checked by the national Bone Marrow Donor Registry. Results: According to the FAB/WHO classification at diagnosis, 22 pts had RA/RARS/RCMD, 40 RAEB1, 30 REAB2 and 9 RAEB-t/AML. 34 pts had progressed to a more advanced disease before allo-SCT. At diagnosis, 89 patients had an IPSS int-2 or higher. At transplant, 36 pts were responders (CR, PR, CRm) and 62 with progressive disease (relapsed/refractory, untreated or stable disease without hematological improvement). Median age at transplantation was 54 years (range, 22-69). Pts received myeloablative conditioning (n=46) and nonmyeloablative (n=55). In this series, 48 patients received ATG as part of conditioning ('ATG' group), whereas 53 did not ('no-ATG’ group). As of April 1st 2011, 44 patients died of relapse and 22 of TRM. 3-year relapse, overall and event-free survival rates were not significantly different between the two groups. In contrast, the cumulative incidence of grade 2-4 acute GVHD was 48% in the no-ATG group and 30% ATG group (P <.005). Although the cumulative incidence of chronic GVHD was similar in the no-ATG and ATG groups, a trend for a lower TRM was observed in the ATG group (p=.06). In multivariate analysis, the absence of use of ATG was associated with an increased risk of acute grade 2-4 [HR = 1.92, p=.044]. Conclusions: The addition of ATG to the conditioning regimen resulted in a decreased incidence of acute GVHD without increasing relapse rates and compromising survival of patients undergoing allo-SCT for poor risk cytogenetic MDS.