ALBERT

Description: Introduction: Recently, theuse of high-dose post-transplant cyclophosphamide (PTCY) has contributed to reconsider T-replete haplo-identical allo-SCT because of the lower incidence of severe graft-versus-host disease (GVHD) observed in patients. However, the influence of PTCY on early outcomes has been poorly studied so far, especially in comparison to the standard use of anti-thymoglobulin (ATG) as GVHD prophylaxis. Patients and Methods: This retrospective study was conducted at the University Hospital of Nantes with the aim to compare the incidence of early outcomes (engraftment, neutrophils and platelets recovery, viral infections (HHV-6, CMV, EBV, BKv, ADV), acute GVHD, relapse or deaths and day+100 non-relapse mortality (NRM)) between patients receiving either PTCY (n=30) or ATG (n=46) as part of GVHD prophylaxis for a RIC allo-SCT. In the PTCY group, RIC was the Baltimore regimen (Luznic, BBMT 2008) in 17 patients while 9 patients received clofarabine instead of fludarabine because of a myeloid malignancy and 4 patients a sequential approach. In this group, 6 and 24 patients received 1 or 2 days of PTCY, respectively, while donors were matched (sibling n=2, unrelated n=5) in 7 cases and haplo-identical in 23, respectively. All patients received cyclosporine + MMF with PTCY as GVHD prophylaxis. In the ATG group (2 days of ATG for siblings and 10/10, 3 days for 9/10), 13, 11 and 22 patients received respectively a FB2, FB3 or CloB2 RIC regimen (Chevallier, Haematologica, 2014). Donors were siblings in 18, matched unrelated in 23 and mismatched unrelated (9/10) in 5. GVHD prophylaxis was cyclosporine alone in case of sibling donors and cyclosporine +MMF for all other cases. The characteristics of both groups (PTCY vs ATG) were similar in terms of gender (male: 63% vs 54%), type of disease (myeloid: 67% vs 63%) and disease status at transplant (complete remission: 43% vs 67%). PTCY patients were significantly younger (median age: 55.5 vs 63 years, p=0.01) and had been previously allografted in a significantly higher proportion (40% vs 4%, p=0.003). Patients were transplanted between March 2012 and April 2015 and were considered up to day+100 post-transplant. All patients received peripheral blood stem cells as stem cell source except one patient in the PTCY group who received bone marrow. Results: All patients engrafted except one in the ATG group. The median time of neutrophils recovery was similar between both groups (PTCY 18 days vs ATG 19 days, p=0.9). Conversely, median time of platelets recovery was significant higher for the PTCY group (27 vs 13 days, p

Description: HHV-6 reactivation and HHV-6 encephalitis have been identified as significant complications in the post allo-SCT setting, especially in patients receiving UCB as the stem cell source (Scheurer et al, BMT, 2012). It is known that HHV-6 reactivations occur mainly within the first month post-transplant and may persist few months after allo-SCT (Chevallier et al, BMT, 2010). At our knowledge, no study has evaluated the long-term persistence of HHV-6 infection and its consequences in patients after allo-SCT. Here we have compared long-term HHV-6 reactivation and immune reconstitution (T, B and NK cells, CD3+, CD4+ and CD8+ T cells, gammaglobulin) between two cohorts of patients who received either double UCB units (n=23) or PBSC (n=25) as stem cells source for allo-SCT between February 2006 and January 2012. Patients were collected prospectively between October 2012 and June 2013. The median time between the graft and the time of analysis were 4 years for the UCB group vs 3.8 years for the PBSC group (p=NS). All patients were fit and in persistent complete remission at time of analyses. There were no differences between UCB vs PBSC groups in term of sex (male: 56% vs 55%), type of disease (myeloid: 52% vs 55%), disease status at diagnosis (high-risk: 89% vs 71%), conditioning regimen (RIC: 83% vs 84%) or median year of transplant (2008 vs 2009). The use of ATG was significantly higher in the PBSC group: 93% of cases vs 10%, p

Description: Abstract 1931 Introduction: Cord Blood (CB) are increasingly used as an alternative stem cells source in adults for allogeneic Stem Cell Transplantation (allo-SCT). The risk of human herpes virus (HHV-6) reactivation is significantly higher after CB transplant vs unrelated peripheral blood stem cells (PBSC) allo-SCT (Chevallier et al, BMT 2010). Higher HHV-6 cell receptor CD46 expression on progenitor cells in CB may explain this difference (Thulke et al, Virol J 2006). Patients and Methods: We have prospectively compared the HHV-6 cell receptor CD46 expression on various cell subsets of three freshly harvested blood sources on one hand and of three graft sources on the other hand. 52 samples were used for the purpose of this study. They were issued from peripheral blood (PB, n=10), G-CSF mobilised PB (GCSF-PB, n=10), cord blood (CB, n=10), unmanipulated bone marrow (uBM, n=5), leukapheresis product (LP, n=10) and thawed CB graft (n=7). CD46 expression was assessed by FACS analysis using a FACS CANTO II (BD Biosciences, San Jose, CA, USA) on total lymphocytes, monocytes, NK cells, T and B cells subsets, plasmacytoid (pDCs) dendritic cells and stem cells. Results: As all cell subsets were found CD46 positive, CD46 mean fluorescence intensity (MFI) was then considered for comparison. When considering the three blood sources, CD46 MFI were found similar on T cells, CD4-/CD8+ and CD4-/CD8- T cells, NKT cells, Tregs, memory B lymphocytes, pDCs and CD34+ stem cells. CD46 MFI was significantly lower on CD4+/CD8- and CD4+/CD8+ T cells, transitional B cells, total and naïve B lymphocytes, and NK cells in CB while higher on monocytes. The highest CD46 MFI was observed on monocytes in CB and on CD4+/CD8+ T cells in GCSF-PB and PB. Also, highest CD46 MFI was detected on T cells compared to B lymphocytes and NK cells in all blood sources while CD46 MFI was higher on CD4+/CD8- T cells compared to CD8+/CD4- T cells. When considering the three graft sources, CD46 MFI was similar on CD4-/CD8- T cells and NKT cells. CD46 MFI was found significantly lower on all other sub-populations in thawed CB graft, except monocytes. The highest CD46 MFI was observed on monocytes in CB graft, on CD4+/CD8+ T cells in LP and on monocytes and on CD4+/CD8- T cells in uBM. Also, highest CD46 MFI was detected on T cells compared to B lymphocytes and NK cells in all graft sources while CD46 MFI was higher on CD4+/CD8- T cells compared to CD8+/CD4- T cells. Conclusion: This original study shows strong differences in term of quantitative CD46 expression between several blood and grafts samples. Our results suggest that other factors (such as another HHV-6 cell surface receptor) than the qualitative CD46 expression play a role in the higher HHV-6 reactivation observed after CB transplant in adults. Disclosures: No relevant conflicts of interest to declare.