Reduced Intensity Conditioning Regimen Prior to Unrelated Cord Blood Transplantation In Patients with Acute Myeloid leukemia : Preliminary Analysis of a Prospective Phase II Multicentric Trial on Behalf of Societe Française De Greffe De Moelle Osseuse Et Therapie Cellulaire (SFGM-TC) and Eurocord

Abstract 911

Unrelated cord blood transplantation (UCBT) after reduced intensity conditioning regimen (RIC) has extended the use of CB in elderly patients(pts) and those with co-morbidities without an HLA identical donor. To evaluate RIC-UCBT in pts with Acute Myeloid Leukemia (AML), we conducted a prospective phase II multicentric trial in France, whose primary objective was to show a reduction in non-relapse mortality (NRM) from 40% (based on registry data) to 20%. We calculated that at least 76 pts should be enrolled (for controlling type I and type II error rates both at 5%). Inclusion criteria were: 1) de novo and secondary AML, 2) lack of HLA identical unrelated donor (10/10 or 9/10), 3) cord blood units (CBU) with less than 3/6 HLA disparities, 4) a nucleated cell dose before freezing of more than 3×10⁷/Kg within 1 or 2 CBU. The conditioning regimen consisted of cyclophosphamide (50mg/kg) +fludarabine (200mg/m2)+ TBI(2Gy), CsA +MMF as GVHD prophylaxis and GCSF from day +1. Supportive care and infections prophylaxis were given according to the EBMT recommendations. Patients were enrolled in 23 centers from Oct. 2007 to Sept. 2009. This preliminary results include 65 pts, 55% female, median age at diagnosis of 49.7 years (range, 13–65), mostly with de novo AML, extramedullary leukemic involvement of AML in 8%. Cytogenetics was normal in 33 pts (52%), of those 10/33 were FLT3 positive, and abnormal in 48%, including 36% with a complex karyotype and/or abnormality of chr 5, 7, 11 and inv 3. Nine (14%) pts had been previously transplanted. 57% of the pts were transplanted in 1st complete remission (CR1), 40% in CR2 and 3% in non-remission. Median time from diagnosis to transplant was 6.6 months (range, 3.7–24) in pts transplanted in CR1 and was 21 months (range, 5.1–93) for pts transplanted in CR2. Median age was 51 years (14-65), median weight was 65 kg (49-105), 51% were CMV-seropositive. The median follow-up for survivors was 20 months (range 9–30). 51% of the pts had no comorbidity. The Sorror score was 1 in 17%, 2 in 8 and 3 or more in 24%. 60% of the pts received 2 CBU. The median number of nucleated cells (NC) and CD34 infused after thawing were 3.4 x10⁷/kg (0.5-6) and 1.1 x10⁵/kg (0.10-3.1), respectively. Patients transplanted with a single CBU received a median of 2.92 NC x10⁷/kg and of 0.92 CD34 x10⁵/kg. Those transplanted with 2 CBU received 3.5 x10⁷/kg and 1.1 x10⁵/kg, respectively; 3% of the units were HLA matched, 23% 5/6 and 74% 4/6 (HLA defined as low resolution for HLA-A and B and high resolution for HLA-DRB1; the highest HLA disparity between CB and pts was taken into consideration in double CBT). ABO major incompatibility was observed in 40% of the pts (in double CB, the highest incompatibility was considered).