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
Authors: Rio Bernard , Chevret Sylvie , Vigouroux Stephane , Chevallier Patrice , Furst Sabine , Sirvent Anne , Bay Jacques-Olivier , Socie Gerard , Ceballos Patrice , Huynh Anne , Cornillon Jérôme , Francois Sylvie , Legrand Faezeh , Yakoub-Agha Ibrahim , Michel Gerard , Maillard Natacha , Margueritte Genevieve , Maury Sebastien , Uzunov Madalina , Bulabois Claude Eric , Michallet Mauricette , Clement Laurence , Dauriac Charles , Bilger Karin , Simon Tabassome , Gluckman Eliane , Milpied Noel , Rocha Vanderson 
Published: October 2019

Abstract
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).

Results:
Median time to cell recovery was 15 days (95CI: 11–20) for neutrophils and 43 days for platelets. Cumulative incidence (Cum Inc) of neutrophil recovery at day 60 was 86% (95CI: 78–95%); 85% (95CI: 69–99) after 1 CBU and 87% (95CI: 76–98) after 2 CBU (p=ns). Twenty-three pts developed grade II-IV acute(a) GVHD (grade II: n=8; grade III n=14; grade IV n=1); Cum Inc of aGVHD (II-IV) at day 100 was 37% (95CI: 24–47%)(38% (95CI: 20–57) for 1 and 34% (95CI: 19–49) for 2 CBT (p=ns)). At 1 year post-transplant, Cum Inc of chronic GVHD was 13% (95CI: 3–23%) and Cum Inc of NRM was 18% (95CI: 8–28%), with variations according to patient status (20% for pts transplanted in CR1 and 13% for pts transplanted in CR2) or number of CBU (21% for 1 CBU and 16% for 2 CBU). At 1 year, Cum Inc of relapse was 30% (95CI : 19–42%); it was 37% for patients transplanted in CR1 and 19% for patients transplanted in CR2 (p=ns), 32% for those transplanted with one CBU and 29% for those transplanted with 2 CBU (p=ns). At 1 year, overall survival was 60% (95CI: 48–74%) and LFS was 52% (95CI: 41–66%). LFS was 43% (95CI: 29–63%) for pts transplanted in CR1, 68% (95CI: 52–89%) for those transplanted in CR2 (p=0.05). According to number of graft, LFS was 48% (95CI: 31–73%) for those transplanted with 1 CBU and 55% (95CI: 41–74%) for those transplanted with 2 CBU (p=ns).
In conclusion, the preliminary results of this prospective trial show the interest of RIC-UCBT in patients with AML without a HLA identical donor. A decreased NRM was observed, based on data with a median follow-up of 20 months. We have observed better LFS in patients transplanted in CR2, probably related to the very high risk group of patients transplanted in CR1. These results will be confirmed in the whole enrolled cohort.

Disclosures:
No relevant conflicts of interest to declare.