Peripheral Blood Stem Cell Recipients Research Articles

Differential clinical impact of letermovir prophylaxis according to graft sources: a KSGCT multicenter retrospective analysis

AbstractClinically significant cytomegalovirus infection (csCMVi) is frequently observed after allogeneic hematopoietic stem cell transplantation (HSCT) and prophylaxis with letermovir is commonly adopted. However, the clinical benefit of letermovir prophylaxis according to graft sources has not been sufficiently elucidated. We retrospectively analyzed 2194 recipients of HSCT who were CMV-seropositive (236 with letermovir prophylaxis and 1958 without prophylaxis against CMV). csCMVi was significantly less frequent in patients with letermovir prophylaxis than in those without (23.7% vs 58.7% at 100 days after HSCT, P < .001) and the same trend was seen when recipients of bone marrow (BM), peripheral blood stem cell (PBSC), or cord blood (CB) transplantation were separately analyzed. In recipients of BM, nonrelapse mortality (NRM) was significantly lower in the letermovir group at 6 months after HSCT (5.0% vs 14.9%, P = .018), and the same trend was observed in recipients of PBSCs (14.7% vs 24.8%, P = .062); however, there was no statistical significance at 1 year (BM, 21.1% vs 30.4%, P = .67; PBSCs, 21.2% vs 30.4%, P = .096). In contrast, NRM was comparable between recipients of CB with and without letermovir prophylaxis throughout the clinical course (6 months, 23.6% vs 24.3%, P =.92; 1 year, 29.3% vs 31.0%, P = .77), which was confirmed by multivariate analyses. In conclusion, the impact of letermovir prophylaxis on NRM and csCMVi should be separately considered according to graft sources.

Alemtuzumab, Dual Graft-versus-Host Disease Prophylaxis, and Lower CD3+ T Cell Doses Equalize Rates of Acute and Chronic Graft-versus-Host Disease in Pediatric Patients Receiving Allogeneic Hematopoietic Stem Cell Transplantation with Matched Unrelated Donor Peripheral Blood Stem Cells or Bone Marrow Grafts

Data comparing hematopoietic stem cell transplantation (HSCT) using bone marrow (BM) or peripheral blood stem cell (PBSC) grafts in children after alemtuzumab-based conditioning are lacking. We investigated whether in vivo T cell depletion using alemtuzumab could reduce the risk of severe acute graft-versus-host disease (aGVHD) and chronic GVHD (cGVHD) after HSCT with matched unrelated donor (MUD) BM or PBSCs. This retrospective multicenter study included 397 children (BM group, n = 202; PBSC group, n = 195) who underwent first MUD HSCT at 9 pediatric centers in the United Kingdom between 2015 and 2019. The median age at transplantation was 7.0 years (range, .1 to 19.3 years), and the median duration of follow-up was 3.1 years (range, .3 to 7.5 years). The 3-year overall survival was 81% for the entire cohort (BM group, 80%; PBSC group, 81%). The incidence of grade II-IV aGVHD was significantly higher in the PBSC group (31%) compared to the BM group (31% versus 19%; P = .003), with no difference in the incidence of grade III-IV aGVHD (BM, 7%; PBSC, 12%; P = .17). CD3+ T cell dose >5 × 108/kg and the use of PBSCs were independent predictors of grade II-IV aGVHD. When considering CD3+ T cell dose and GVHD prophylaxis, PBSC transplantation with a calcineurin inhibitor (CNI) and mycophenolate mofetil (MMF) and a CD3+ T cell dose ≤5 × 108/kg had a comparable grade II-IV aGVHD to BM transplantation plus a CNI (20% versus 18%; P = .52). PBSC transplantation was associated with a lower incidence of cGVHD compared to BM transplantation (6% versus 11%; P = .03). Within the limits of this study, we identified a potential strategy to reduce the risk of severe GVHD in pediatric PBSC recipients that includes a combination of in vivo T cell depletion using alemtuzumab and dual GVHD prophylaxis (with a CNI and MMF) and limiting the CD3+ T cell dose to ≤5 × 108/kg.

Outcomes after Bone Marrow Versus Peripheral Blood Stem Cell Matched Unrelated Donor Hematopoietic Stem Cell Transplantation

Background: Matched unrelated donors (MUD) have become an acceptable alternative donor for patients requiring potentially curative hematopoietic stem cell transplantation (HSCT) and lacking a matched sibling donor. Patients may undergo a bone marrow (BM) or peripheral blood stem cell (PBSC) graft, with previous studies showing similar survival outcomes. However, BM grafts have shown a lower incidence of chronic graft-versus-host disease (GVHD) but a higher relapse rate and slower engraftment. We aimed to compare the outcomes of BM versus PBSC in patients undergoing MUD HSCT. Methods: For this retrospective single-center study, we included all (n=276) adult MUD HSCT recipients at the University of Kansas Medical Center who had at least one year of follow-up (August 2016 to July 2021). We conducted a bivariate analysis using chi-squared and ANOVA tests. The Kaplan-Meier and regression analyses were also performed. Data analyses were conducted using SPSS version 28. Statistical significance was considered at p&amp;lt;0.05. Results: Our study included 276 MUD patients including 110 PBSC (40%) and 166 BM (60%) grafts. The median age was 55 (range 21-77) years, and 158 patients (57%) were males. Eighteen patients (6%) were ethnic minorities, and 89 (32%) patients had a Karnofsky performance status of ≥90%. 118 (43%) patients had a hematopoietic cell transplantation-specific comorbidity index of 3 or higher. Hematologic diseases included acute myeloid leukemia (n=119, 43%), myeloid disorders (n=77, 28%), acute lymphoblastic leukemia (ALL) (n=35, 13%), Lymphoma (n=15, 5%), and others (n=30, 11%). Sixty-two percent of patients were in complete remission at the time of transplantation, and patients not in remission included myelodysplastic syndrome, myelofibrosis, and lymphoma patients. Reduced-intensity conditioning (RIC, n=162, 58%) and myeloablative conditioning (MAC) (n=114, 41%) were used. The median follow-up was 55 (21-73) months. Overall survival (OS) was not reached in either BM or PBSC MUD HSCT group, while a median disease-free survival of 45 and 49 months was noted in PBSC and BM groups respectively (p=0.915). We observed similar rates of relapse (25% vs 27%, p=0.413), one-year overall survival (75% vs 72%, p=0.679), one-year disease-free survival (63% vs 62%, p=1.00), and one-year non-relapsed morality (NRM, 23% vs 21%, p=0.779) after PBSC or BM graft. Bone marrow graft recipients had delayed engraftment of neutrophils (20 days vs 16 days, p&amp;lt;0.001) and platelets (&amp;gt;20 K/uL: 24 days vs 16 days, p&amp;lt;0.001; &amp;gt;50 K/uL: 28 days vs 18 days, p=0.006) compared to PBSC recipients. Bone marrow graft recipients had similar rates of grade II-IV acute GVHD (50% vs 52%, p=0.714) and grade III-IV GVHD (12% vs 11%, p=0.847), but lower rates of 1-year chronic GVHD (39 % vs 55%, p=0.014) compared to PBSC recipients. In the subgroup analysis stratified by conditioning intensity, faster engraftment of neutrophils (median 16 vs 21 days, p&amp;lt;0.001) and platelets (&amp;gt;20 K/uL: 18 days vs 27 days, p&amp;lt;0.001; &amp;gt;50 K/uL: 18 days vs 33 days, p&amp;lt;0.001) was observed with PBSC as compared to BM graft in myeloablative transplant recipients, while there was no statistically significant association with the rates of acute or chronic GVHD, NRM, Relapse, DFS, and OS after a PBSC or BM graft. Among the RIC transplant recipients, faster neutrophil engraftment (mean 17 vs 20 days, p&amp;lt;0.001) and higher 1-year extensive chronic GVHD (52% vs 32%, p=0.015) were observed with PBSC compared to BM graft whereas no statistically significant difference was noted in platelet engraftment, acute GVHD, NRM, Relapse, DFS, and OS after a BM or PBSC graft. Conclusions: Allogeneic matched unrelated donor hematopoietic stem cell transplant recipients had similar rates of overall and disease-free survival, relapse, non-relapse mortality, and acute GVHD after a bone marrow or peripheral blood stem cell graft; however, delayed neutrophil and platelet engraftment with a lower incidence of chronic GVHD was noted after a bone marrow graft compared to peripheral blood stem cell graft.

Improved Outcomes of UM171-Expanded Cord Blood Transplantation Compared with Other Graft Sources: Real World Evidence

Background: Cord blood (CB) transplantation (CBT) has several advantages compared with other graft sources. CBT has low rates of chronic graft-versus-host disease (GVHD) and allows for several human leukocyte antigen (HLA) mismatches, thus expanding donor availability. However, CBT has fallen into disfavor because of its low cell dose and associated prolonged cytopenias, which result in prolonged hospitalization and higher risk of non-relapse mortality (NRM). Furthermore, the need for large CBs leads to selection of poorly HLA matched CBs, further increasing NRM. UM171 is a small molecule that expands hematopoietic stem cells. From 2016 to 2018, 22 patients with high-risk malignancies who lacked a donor were transplanted on a phase I-II clinical trial with a single UM171-expanded CB (Cohen S et al. Lancet Haematol 2019) after a myeloablative conditioning. The goal was to accelerate engraftment while selecting smaller, better HLA matched CBs to decrease NRM while preserving the benefits of CBT. Results demonstrated that indeed UM171-expanded CB has the potential to overcome slow neutrophil engraftment and diminish NRM. The aim of the current analysis was to examine outcomes after conventional single/double ≥ 4/6 HLA-matched CB and 8/8-matched unrelated donor (MUD) peripheral blood stem cell (PBSC) transplantation with UM171-expanded CBT. Methods: Data on UM171-expanded adult CBT recipients were drawn from the phase I-II trial. Data for adult recipients of myeloablative CB and PBSC transplants for hematologic malignancies (acute myeloid and lymphoblastic leukemia, chronic myeloid leukemia, non-Hodgkin and Hodgkin lymphoma) in the United States and Canada during 2014-2019 with a Karnofsky performance status (KPS) score ≥70 were obtained from the Center for International Blood and Marrow Transplant Research (CIBMTR) database. CB recipients who received anti-thymocyte globulin or alemtuzumab in the conditioning were excluded from the CIBMTR population. Patients were directly matched for the number of prior allogeneic transplants (alloHCT), refined disease risk index (for 1st alloHCT), disease status (for 2nd alloHCT), and acute myeloid leukemia cytogenetic risk. Patients were matched by propensity score for age, comorbidity index and KPS. CIBMTR attempted to identify 4 controls per UM171 patient. Clinical outcomes included engraftment, NRM, progression-free survival (PFS), overall survival (OS), relapse, GVHD-free, relapse-free survival (GRFS), acute GVHD grade III-IV, and chronic GVHD. PFS, OS, and GRFS were estimated by Kaplan-Meir method; other outcomes were calculated using cumulative incidence estimates; marginal Cox regression models were used for analyzing NRM and GRFS. Results: Overall, 137 CIBMTR (67 CB, 70 PBSC) and 22 UM171-expanded CBT patients participated. Univariate analysis and marginal Cox regression analysis results are shown in Tables 1 and 2, respectively. Median time to neutrophil engraftment was 18 days (range 10-30) for UM171-expanded CB recipients compared to 21 days (range 8-53) for CIBMTR CB recipients (p<0.01) (data not shown). Univariate analysis revealed less 1- and 2-year NRM, improved 2-year PFS, improved 1-year OS, and 1- and 2-year GRFS for UM171-expanded CBT compared to CIBMTR CB controls. The UM171 cases had less 1- and 2-year NRM, improved 2-year PFS, and improved 1- and 2-year GRFS compared to CIBMTR PBSC controls. Furthermore, UM171-expanded CB patients experienced less acute GVHD III-IV and chronic GVHD compared to PBSC recipients. In marginal Cox regression analysis, UM171-expanded CBT recipients were 87% and 63% less likely than CIBMTR CB controls to experience NRM and GRFS events, respectively, and 73% less likely to experience GRFS events than CIBMTR PBSC recipients. Conclusions: This real-word evidence suggests that UM171-expanded CB recipients have select improved outcomes compared to conventional CB and MUD PBSC recipients. While this study was limited by the small number of UM171 CB trial participants and inability to identify the planned number of controls for each case, UM171 expansion of CB appeared to achieve the desired outcome of maintaining CB's benefits while removing its disadvantages. Thus, prospective randomized studies of UM171-expanded CBT compared to MUD PBSC alloHCT are warranted to confirm these results. Study Support: This study was funded by ExCellThera. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

The Outcome of Allogeneic Hematopoietic Stem Cell Transplantation From Different Donors in Recipients With Mucopolysaccharidosis.

There is limited information regarding hematopoietic stem cell transplantation (HSCT) for mucopolysaccharidosis (MPS) IV and VI. This study examined the full donor chimerism, specific lysosomal enzyme levels, and the survival of different MPS children after HSCT from various donor sources and compared the prognosis. A total of 42 children with MPS underwent HSCT, 9 cases were type I, 14 were type II, 15 were type IV, and 4 were type VI. A total of 24 patients received peripheral blood stem cells (PBSC) and 18 patients received umbilical cord blood (UCB). Patients who received PBSC were conditioned with intravenous (IV) busulfan every 6 h for a total of 16 doses, IV cyclophosphamide (CY, 200 mg/kg), and antihuman thymocyte globulin (ATG, 10 mg/kg). While conditioning regimen of patients who received UCB was adjusted to ATG (preposed, pre-) + busulfan + fludarabine + Cy, which includes IV ATG (pre-, 6 mg/kg), IV busulfan every 6 h for a total of 16 doses, IV fludarabine (200 mg/m2) and CY (200 mg/kg). Also, 95.2% (40 of 42) of patients achieved full donor chimerism, and all patients’ specific lysosomal enzyme levels reached normal. The estimated overall survival (OS) at 1 year was 92.9%. There was no significant difference in 1-year OS between patients who received PBSC transplantation and those who received UCB grafts (87.5% vs. 100%, p = 0.0247). The incidence of acute and chronic GVHD did not differ between them. The incidences of pneumonia in PBSC recipients and UCB recipients were 45.8 and 33.3%, respectively, but there few patients suffering from respiratory failure (4.2 and 5.6%, respectively) due to pneumonia. The incidence of cytomegaloviremia was also high in both groups, 58.3 and 44.4% respectively, However, no patient developed CMV disease. All deaths (3 of 42) occurred in patients receiving PBSC grafts, and there was no death in patients receiving UCB grafts. There was no death after transplantation in patients with MPS IV and VI. In addition, respiratory and nervous system functions were improved, whereas valvular heart disease was improved in some patients but progressed in more patients after transplantation. In summary, HSCT is a good therapeutic option for MPS, not only for patients with MPS I or II but also for those with MPS IV or VI. The specific lysosomal enzyme levels can be completely restored to normal, which is the basis for patients to resolve a broad range of clinical outcomes. Moreover, UCB with suitable HLA (HLA-match above 7/10 and 4/6) is a suitable donor source for MPS. Patients who underwent UCB transplantation using the conditioning regimen ATG (pre-) + busulfan + fludarabine + Cy can achieve a higher proportion of full donor chimerism and survival with less severe complications. HSCT can improve organs function in patients with MPS, but it is still worth exploring.

Advantages of peripheral blood stem cells from unrelated donors versus bone marrow transplants in outcomes of adult acute myeloid leukemia patients

Background aimsIn allogeneic stem cell transplantation, unrelated donors are chosen in cases where appropriate related donors are not available. Peripheral blood stem cells (PBSCs) are more often selected as a graft source than bone marrow (BM). However, the prognostic benefits of PBSCs versus BM transplants from unrelated donors have not been carefully examined in patients with acute myeloid leukemia (AML). This study compared outcomes of adult AML patients who underwent unrelated PBSC and BM transplantation, evaluating post-transplant complications, including engraftment, graft-versus-host disease (GVHD) and infections, and determined subgroups of patients who are most likely to benefit from unrelated PBSCs compared with BM transplants. MethodsThe authors analyzed 2962 adult AML patients who underwent unrelated PBSC or BM transplants between 2011 and 2018 (221 PBSC and 2741 BM) using the Japanese nationwide registry database, in which graft source selection is not skewed toward PBSCs. ResultsIn 49.7% of patients, disease status at transplantation was first complete remission (CR1). In 57.1% of cases, HLA-matched donors were selected. Myeloablative conditioning was performed in 75.1% of cases, and anti-thymocyte globulin (ATG) was added to conditioning in 10.5%. Multivariate analyses showed a trend toward favorable non-relapse mortality (NRM) in PBSC recipients compared with BM recipients (hazard ratio [HR], 0.731, P = 0.096), whereas overall survival (OS) (HR, 0.959, P = 0.230) and disease-free survival (DFS) (HR, 0.868, P = 0.221) were comparable between PBSC and BM recipients. Although the rate of chronic GVHD (cGVHD) was significantly higher in PBSC patients (HR, 1.367, P = 0.016), NRM was not increased, mainly as a result of significantly reduced risk of bacterial infections (HR, 0.618, P = 0.010), reflecting more prompt engraftments in PBSC recipients. Subgroup analyses revealed that PBSC transplantation was advantageous in patients transplanted at CR1 and in those without ATG use. PBSC recipients experienced significantly better OS and/or DFS compared with BM recipients in this patient group. ConclusionsThe authors' results confirmed the overall safety of unrelated PBSC transplantation for adult AML patients and suggested an advantage of PBSCs, especially for those in CR1. Further optimization of the prophylactic strategy for cGVHD is required to improve the overall outcome in transplantation from unrelated PBSC donors.

MAIT and Vδ2 Unconventional T Cells Predict Favorable Outcome after Allogeneic HCT and Are Supported By a Diverse Intestinal Microbiome

MAIT and Vδ2 Unconventional T Cells Predict Favorable Outcome after Allogeneic HCT and Are Supported By a Diverse Intestinal Microbiome

CD34+ Stem Cell Selection and CD3+ T Cell Add-Back from Matched Unrelated Adult Donors in Children with Primary Immunodeficiencies and Hematological Diseases

Less than 25% of children who require hematopoietic stem cell transplantation (HSCT) for primary immunodeficiencies (PIDs) or genetic hematological diseases have an HLA-identical sibling. For them, a matched unrelated donor (MUD), although baring a greater risk of graft failure, delayed engraftment and immune reconstitution, and severe graft-versus-host disease (GvHD), represents a valid alternative. The stem cell source is also important, as unprocessed peripheral blood stem cells (PBSCs) contain 5 to 10 times more T cells than bone marrow (BM)-derived grafts, a major risk especially for small children with PID. A CD34+ positive selection can mitigate HLA compatibility issues, but the resulting CD3+ T cell depletion hampers engraftment and facilitates infections. To mitigate those problems, we decided to add back a certain number of T cells (30×106 cells/kg body weight [BW]) to the positive CD34+ selection derived from MUD BM or PBSCs and report the results in terms of time to engraftment and immune reconstitution, GvHD incidence, infections, and survival. Our aim was to show not only the feasibility and clinical efficacy of this addback but also that PBSC-derived CD34+ selected grafts with calibrated T cell addback would be equivalent to BM-derived grafts. We analyzed retrospectively our single-center cohort of 76 children (median age, 1.9 years) affected by PID (61) and hematological diseases (15) who received a total of 79 MUD HSCTs with CD34+ selection and addback of 30×106 CD3+ cells/kg BW between 2001 and 2019. We used descriptive and analytic statistics (chi-square, Student's t-test, Mann-Whitney U test, as appropriate) and constructed Kaplan-Meier curves using the log-rank test to compare patients grafted with BM or PBSC-derived inocula. The two groups showed no statistically significant differences in terms of age, sex, HLA-mismatch, or amount of CD3+ cells/kg BW added back to the CD34+ selection. However, the latter being higher in the PBSC group (P=.0001). Overall engraftment rate was 96% (73/76) and occurred faster in the PBSC group than in BM recipients: polymorphonuclear cells, 16 versus 21 days (P=.006); platelets, 15 versus 22 days (P=.001). GvHD incidence was low. No acute GvHD was diagnosed in 24 children, whereas grades I, II, III, and IV occurred in 19, 28, five, and three children, respectively (P not significant). Chronic GvHD was seen in only two children. The CD4+ count at six months after HSCT was higher in PBSC recipients as compared to those receiving BM (184 versus 88 CD4+ cells; P=.003). Overall survival for the whole cohort was 80% at 10 years, with no significant difference between the two stem cell sources (P not significant). Viral infections occurred among five of the PBSC grafted children and 14 in the BM group (P not significant), and no patient suffered from post-transplant lymphoproliferative disorder (PTLD). The results we present show that an addback of 30×106 donor CD3+ cells/kg recipient BW to a MUD BM or PBSC-derived CD34+ selection gives promising results in infants and young children undergoing HSCT for PID or hematological diseases. Furthermore, with this manipulation the inherent limits of PBSC-derived grafts can be overcome, allowing both swift engraftment and immune reconstitution without an increase in GvHD, infections, or PTLD.

Impact of Cryopreservation of Donor Grafts on Outcomes of Allogeneic Hematopoietic Cell Transplant (HCT)

Introduction: Cryopreservation of peripheral blood stem cell (PBSC) or bone marrow (BM) grafts is rarely performed, thus information about the effect of cryopreservation on graft characteristics and HCT outcomes is limited. Given the global pandemic leading to changing practices for donor graft collection and increasing utilization of cryopreservation, we evaluated the outcomes of HCT recipients who received either fresh or cryopreserved allogeneic BM or PBSC grafts. The primary endpoint was engraftment. Secondary endpoints were incidence of acute graft-vs.-host disease (aGVHD), relapse, transplant related mortality (TRM), disease free survival (DFS), and overall survival (OS). Methods: We included 7397 patients transplanted between 2013 and 2018. 1883 cryopreserved graft recipients were divided into three cohorts based on graft source and donor type: matched related (MRD) PBSC (n=1,051), matched unrelated (MUD) PBSC (n=678), and matched related or unrelated bone marrow donors (n=154). All patients received conventional calcineurin-based GVHD prophylaxis strategies. Patients who received cryopreserved grafts were matched with 5514 patients who received fresh adjusting for graft type (BM vs. PB), donor source (MRD vs. 8/8 MUD), Disease Risk Index (DRI, low risk vs. intermediate risk vs. high risk), recipient age (within 5-years) and propensity score (within 1 standard deviation from pooled sample). The propensity score was based on age, Karnofsky score, diagnosis, disease risk index, HCT-comorbidity index, and conditioning intensity. The level of statistical significance for the main analyses was p&amp;lt;0.01 due to multiple comparisons. The reason for cryopreservation was available on a subset of URD product recipients. Results: Baseline characteristics for all cohorts are shown in Table 1. CD34+ doses reflect enumeration at infusion. In univariate analyses, rates of graft failure and neutrophil recovery at day 28 were similar for cryopreserved and fresh grafts for BM or related PBSC recipients but differed in cryopreserved vs. fresh MUD PBSC (5% vs 2%, p&amp;lt;0.001 and 87 vs 94%, p&amp;lt;0.001, respectively). Rates of platelet recovery within 28 days were similar in marrow cohorts, but lower with cryopreserved related (92% vs 96%, p&amp;lt;0.001) and MUD PBSC (87 vs 94%, p&amp;lt;0.001) grafts. In matched pair multivariable analyses, there were no significant differences in any outcomes with cryopreserved vs fresh BM grafts, irrespective of donor type. With related donor PBSC, cryopreservation was associated with decreased platelet recovery (HR=0.73, CI=0.68-0.78, p&amp;lt;0.001) and an increased risk of both grade II-IV (HR=1.27, CI=1.09-1.48, p=0.002) and grade III-IV (HR=1.48, CI=1.19-1.84, p&amp;lt;0.001) aGVHD, but had no impact on other outcomes. In contrast, with MUD PBSC grafts, cryopreservation was associated with delayed engraftment of neutrophils (HR=0.77, CI=0.71-0.84, p&amp;lt;0.001) and platelets (HR=0.61, CI=0.56-0.66, p&amp;lt;0.001), an increased risk of TRM (HR=1.4, CI=1.18-1.66, p&amp;lt;0.001) and relapse (HR=1.32, CI=1.11-1.58, p=0.002), and decreased DFS (HR=1.36, CI=1.20-1.55, p&amp;lt;0.001) and OS (HR=1.38, CI=1.22-1.58, p&amp;lt;0.001) but did not affect the incidence of aGVHD. In a subset analysis of 299 URD recipients, the most common reason for cryopreservation was delays due to patient-related events, eg., additional chemotherapy, infection. These recipients had decreased OS compared to products cryopreserved for non-patient reasons (HR=0.65, CI=0.44-0.96, p=0.029). Conclusions: The retrospective nature of this analysis, and the fact that cryopreservation is likely to have been performed in recipients with a different (higher) risk profile compared to those receiving fresh products limits our ability to draw firm confusions. Despite these limitations, we conclude that cryopreservation in some patient populations may have a negative impact on engraftment and transplant outcomes. The decision to cryopreserve donor grafts, particularly PBSC grafts, should be carefully considered and highlights the need for further investigation of the effect of cryopreservation of allogeneic grafts where patient factors can be controlled for. Disclosures Farhadfar: CSL Behring: Research Funding; Incyte pharmaceutical: Other: Member of GVHD advisory forum. Frey:Kite Pharma: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Syntax: Consultancy, Honoraria. Devine:Magenta Therapeutics: Consultancy. Shaw:Orca Bio: Consultancy. Wingard:Shire: Other: Personal Fees - serve on data monitoring committee for clinical trial; Ansun: Other: Personal Fees - serve on data monitoring committee for clinical trial; Merck: Other: Personal Fees - serve on data monitoring committee for clinical trial; Cidara: Other: Personal Fees - serve on data monitoring committee for clinical trial; ReViral: Other: Personal Fees - serve on data monitoring committee for clinical trial.

IFNL4 and donor selection for matched unrelated donor haematopoietic stem-cell transplantation

IFNL4 and donor selection for matched unrelated donor haematopoietic stem-cell transplantation

Results of Allogenic Hematopoietic Stem Cell Transplantation in Fanconi Anemia Caused by Bone Marrow Failure: Single-Regimen, Single-Center Experience of 14 Years.

Hematopoietic stem cell transplantation (HSCT) is the only curative treatment for bone marrow failure (BMF) in patients with Fanconi anemia (FA). We retrospectively analyzed the records of patients with FA who underwent HSCT with a radiation-free, reduced-intensity conditioning regimen (fludarabine, cyclophosphamide, and antithymocyte globulin) along with an unmanipulated graft infusion between 2004 and 2018. A total of 44 patients underwent HSCT during the study period. Median age at transplantation was 121 months. Regarding the donor source, 22 transplants (50%) were collected from matched related donors (MRDs), and 22 transplants (50%) were collected from alternative donors (ADs). The median infused CD34+ cell dose was 4.7 × 106/kg (range, 0.8 to 23) in bone marrow or peripheral blood stem cell recipients and 1.2 × 105/kg (range, 1.1 to 3.6) in umbilical cord blood recipients. All but 2 patients achieved primary neutrophil engraftment (95%). In a median follow-up of 36 months (range, 1 to 159), 3-year overall survival was 70.5% in the entire group and 91% in the MRD recipients. Primary causes of death were infections (n = 5), acute grade 3 to 4 graft-versus-host disease (n = 4), and hemorrhagic cystitis (n = 3). All surviving patients have full (n = 29) and acceptable mixed (n = 2) donor chimerism and good clinical status. Our results showed an excellent outcome with unmanipulated grafts using a fludarabine-based, radiation-free preparative regimen for MRD recipients. Even though primary neutrophil engraftment rates were good in AD recipients, intervening complications increased mortality in these patients. In clinics where T cell depletion is not feasible, more effort is warranted to improve outcomes for AD recipients.

Unmanipulated haploidentical transplantation for adult patients with hematological malignancies.

Unmanipulated haploidentical transplantation for adult patients with hematological malignancies.

Kinetics of neutrophil engraftment in allogeneic stem cell transplantation.

Primary graft failure is a lethal complication that occurs after allogeneic stem cell transplantation (allo-SCT) and requires retransplantation. We retrospectively assessed 1,355 patients who underwent allo-SCT at our institute. Following allo-SCT, the cumulative incidence of subsequent neutrophil engraftment was calculated each day after day 5 among patients with white blood cell (WBC) count<100 cells/μL on the respective day. The number of patients with WBC count<100 cells/μL at days 14, 21, and 28 were 372, 55, and 21, respectively. In patients with WBC count<100 cells/μL on day 14, the cumulative incidence of engraftment was lower in recipients of peripheral blood stem cells (PBSCs) and cord blood (CB) compared with recipients of bone marrow (BM) (BM vs. PBSCs vs. CB, 93% vs. 79% vs. 77%, P<0.01). In patients with WBC count<100 cells/μL after day 14, the cumulative incidence of engraftment in recipients of PBSCs became progressively lower (25% at day 21 and 0% at day 28). In patients with WBC count<100 cells/μL on day 28, the cumulative incidence of engraftment was 100% in patients with donor chimerism≥95%, while it was only 13% in those with chimerism<95% (P<0.01). These data provide important information that could be useful in deciding the appropriate time for performing tests in patients with donor chimerism and in those that require retransplantation.

5 Year Health Care Burden after Allogeneic Hematopoietic Stem Cell Transplantation (HSCT): Impact of Graft Source

BACKGROUND: Recipients of allogeneic HSCT experience significant short- and long-term healthcare burdens with differing general patterns of late effects between graft sources. For example, recipients of peripheral blood stem cell (PBSC) grafts benefit from more rapid engraftment after transplant as compared to bone marrow (BM) or umbilical cord blood (UCB), but experience a greater risk of chronic graft-versus-host disease (cGVHD) at later time points after HSCT. Little data exist regarding healthcare burden beyond first year of allogeneic HSCT, limiting our understanding of the long-term impact for each graft source.METHODS: To estimate the healthcare burden in adult allogeneic HSCT recipients over time, we analyzed clinical data from 1077 consecutive allogeneic HSCT recipients at the University of Minnesota Medical Center (UMMC) transplanted between 2000-2016. In order to understand changes in healthcare burden over time, we assessed the raw number of visits (both face-to-face and non-face-to-face care coordination visits), procedures, laboratory studies, medications, and relative value units (RVUs) over 3 time periods: (1) Day 0 to day 100, (2) 101 - 365 days, and (3) >1 year - 5 years after HSCT. We analyzed the counts of these healthcare elements both individually and as a composite score of all these elements (visits, procedures, labs, medications, RVUs). We then compared the estimated healthcare burden by graft source over each time period. We included only patients undergoing their first allogeneic HSCT in this analysis, and we included all clinical data from transplant to death or 5 years, whichever came first. We retained data from patients experiencing post-HSCT relapse in this analysis.RESULTS: Of the 1077 HSCT recipients, 102 received BM, 458 received PBSC, and 517 received UCB (84.7% double). The majority of BM donors were matched but unrelated to the recipient (57%), and the majority of PBSC donors were matched siblings (88%). The median age was 52.2 years (range 18.1 - 75.1 years), and 41.4% of the patients were female. The median distance from the patients' address to the transplant center was <30 miles, with no significant difference between the graft sources at any of the 3 time periods (p=0.12, p=0.10, p=0.09, respectively). The majority of patients had acute myeloid leukemia (40.8%), acute lymphoblastic leukemia (13.7%), non-Hodgkin lymphoma (13%), and myelodysplastic syndrome (12.8%). There was no significant difference in the proportions of patients with death (p=0.50) or relapse/progression (p=0.22) between graft sources over these time periods. As expected from previous data, recipients of PBSC had the lowest median composite healthcare burden in the first 100 days (p<0.01, Figure). During this earliest time period, the median number of laboratory studies (2,213 vs 2,448.0 vs 2,960, p<0.01), medications (132 vs 232 vs 203, p<0.01), and RVUs billed (423.2 vs 480.7 vs 466.7, p<0.01) were significantly lower for recipients of PBSC vs BM vs UCB respectively, with no difference in number of visits (p=0.07). From day 101 - 365, UCB had the lowest composite score (p=0.02) due to the fewest labs and visits performed (p<0.01 for each). There was no difference between medications (p=0.16) or RVUs (p=0.06) between graft sources in this second time period. Beyond 1 year, UCB continued to have the lowest composite score (p=0.02), with the lowest number of visits (p<0.01), labs (p<0.01), procedures (p=0.03), medications (p<0.01), and RVUs (p=0.02) with this graft source compared to BM and PBSC.CONCLUSION: Adult recipients of UCBT appear to experience a lower long-term healthcare burden compared to other graft sources. After the first year post-HSCT, recipients of UCBT have fewer clinic visits, laboratory tests, procedures, and medications. This study is the first step in analysis of complex, long-term healthcare burden data in allogeneic HSCT recipients within a single healthcare system. Despite the absence of cost data and details of care outside of Fairview, these data support the hypothesis that healthcare burden varies by graft source with favorable outcomes in long-term survivors after UCBT compared recipients of BM and PBSC. [Display omitted] DisclosuresBrunstein:Gamidacell: Research Funding. MacMillan:Angiocrine: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Consultancy; Equillium: Consultancy. Wagner:Novartis: Research Funding; Magenta Therapeutics: Consultancy, Research Funding. Weisdorf:SL Behring: Consultancy; Seattle Genetics: Consultancy; Pharmacyclics: Consultancy; FATE: Consultancy; Equillium: Consultancy. Holtan:Incyte: Consultancy.

Proinflammatory Cytokine and Adipokine Levels in Adult Unrelated Marrow Donors Are Not Associated with Hematopoietic Cell Transplantation Outcomes

Graft-versus-host disease (GVHD) is a frequent cause of morbidity and mortality after allogeneic hematopoietic cell transplantation (allo-HCT). GVHD occurs when donor lymphocytes are activated by inflammatory cytokines and alloantigens. The role of donor biologic characteristics, such as basal inflammation, has not been investigated as a risk factor for GVHD but is theoretically transferrable to the recipient. We evaluated donor serum and plasma concentrations of cytokines and adipokines (IL-1β, IL-6, tumor necrosis factor [TNF]-α, leptin, suppression of tumorigenicity-2, and adiponectin) from test (n = 210) and replication (n = 250) cohorts of matched, unrelated transplant peripheral blood stem cell recipients identified through the Center for International Blood and Marrow Transplantation Research between 2000 and 2011 for hematologic malignancies. Hazard ratios were estimated for acute (grades II to IV and III to IV) and chronic GVHD, overall survival, disease-free survival, transplant-related mortality, and relapse for each cytokine or adipokine, adjusting for significant covariates. The lowest cytokine quartile was considered as the reference group for each model. To account for multiple testing P < .01 was considered the threshold for significance. In the test cohort a borderline significant association was identified between donor serum IL-1β concentrations and grades III to IV acute GVHD in the recipient (P = .01), and a significant inverse association was identified between donor TNF-α concentrations and chronic GVHD (P = .006). These findings were not validated in the replication cohort. Although the initial associations between cytokine levels and allo-HCT outcomes were not validated, the idea that donor characteristics may be transferable to the recipient remains an exciting area for future research.

Effect of nonpermissive HLA-DPB1 mismatches after unrelated allogeneic transplantation with in vivo T-cell depletion

AbstractWe investigated the impact of donor-recipient HLA-DPB1 matching on outcomes of allogeneic hematopoietic stem cell transplantation with in vivo T-cell depletion using antithymocyte globulin (ATG) for patients with hematological malignancies. All donor-recipient pairs had high-resolution typing for HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DQB1, HLA-DPB1, and HLA-DRB3/4/5 and were matched at HLA-A, HLA-B, HLA-C, and HLA-DRB1. HLA-DPB1 mismatches were categorized by immunogenicity of the DPB1 matching using the DPB T-cell epitope tool. Of 1004 donor-recipient pairs, 210 (21%) were DPB1 matched, 443 (44%) had permissive mismatches, 184 (18%) had nonpermissive mismatches, in graft-versus-host (GVH) direction, and 167 (17%) had nonpermissive mismatches in host-versus-graft (HVG) direction. Compared with HLA-DPB1 permissive mismatched pairs, nonpermissive GVH mismatched pairs had the highest risk for grade II to IV acute graft-versus-host disease (aGVHD) (hazard ratio [HR], 1.4; P = .01) whereas matched pairs had the lowest risk (HR, 0.5; P < .001). Grade III to IV aGVHD was only increased with HLA-DPB1 nonpermissive GVH mismatched pairs (HR, 2.3; P = .005). The risk for disease progression was lower with any HLA-DPB1 mismatches, permissive or nonpermissive. However, the favorable prognosis of HLA-DPB1 mismatches on disease progression was observed only in peripheral blood stem cell recipients who were in the intermediate-risk group by the Disease Risk Index (HR, 0.4; P = .001) but no other risk groups. Our results suggest avoidance of nonpermissive GVH HLA-DPB1 mismatches for lowering the risk for grade II to IV and III to IV aGVHD. Permissive or nonpermissive HVG HLA-DPB1 mismatches may be preferred over HLA-DPB1 matches in the intermediate-risk patients to decrease the risk for disease progression.

NaïVe T Cell Depletion of PBSC Grafts Results in Very Low Rates of Chronic Gvhd and High Survival

BackgroundGraft-versus-host disease (GVHD) frequently causes morbidity and mortality after allogeneic hematopoietic cell transplantation (HCT) as a result of organ damage and infections. In HLA-identical HCT, GVHD results from recognition by donor T cells of minor histocompatibility (H) antigens on recipient tissues. Complete T cell depletion (TCD) of donor hematopoietic cell products is more effective than pharmacologic immunosuppression for preventing GVHD, but is complicated by delayed immune reconstitution and consequent life-threatening infections.Approaches to HCT which preferentially deplete the T cells that primarily cause GVHD and preserve pathogen-specific T cells may improve HCT outcomes.Mature CD3+ CD8+ and CD3+ CD4+ T cells can be classified into CD45RA+ CD62L+ naïve (TN) and CD45RO+ memory (TM) subsets, the latter of which includes effector memory (TEM) and central memory (TCM) cells. Murine studies in which allogeneic TCD bone marrow (BM) is transplanted with purified T cells from individual T cell subsets to irradiated minor H antigen disparate recipients have demonstrated that the most severe GVHD results from transplanting T cells of the TN subset. Purified TCM causes mild GVHD and TEM do not cause detectable GVHD and can transfer immunity to pathogens.In vitro studies have similarly demonstrated that human donor CD8+ T cells specific for recipient minor H antigens are found predominantly within the TN cell subset, suggesting selective TN cell depletion may alter the GVHD incidence and/or severity in human HCT.Methods and resultsWe developed an effective process for engineering human peripheral blood stem cell (PBSC) grafts that depletes CD45RA+ TN cells and retains CD34+ stem cells and functional CD45RO+ TM cells specific for a broad range of opportunistic pathogens (Bleakley BBMT 2014). We are conducting clinical trials to evaluate the selective depletion of TN cells from HLA-matched allogeneic PBSC grafts for the prevention of GVHD in patients with acute leukemia, the first of which has been published (Bleakley JCI 2015, N=35). Seventy patients have now been treated on three consecutive phase II trials. The median age was 34 years (1-56 years), 56% of patients had a diagnosis of ALL, 46% had previously relapsed or had detectable disease (MRD or relapse) at the time of HCT, and 23% had unrelated donor (URD) grafts. Intensive myeloablative, TBI-containing (13.2Gy) conditioning was used for 63 patients, whilst 7 patients received a medium intensity ’midi’ preparative regimen, including 4Gy of TBI. The TN-depletion procedure was successfully performed on URD PBSC products shipped overnight from donor centers throughout the US, as well as on MRD PBSC collected at our centers. Reliable engraftment with high-level donor chimerism was observed in recipients of ’midi’ as well as intensive myeloablative conditioning. The 2-year estimates of overall survival, disease-free survival, survival free of relapse and chronic GVHD (CRFS) and survival free of relapse, grade II-IV acute GVHD, and chronic GVHD (GRFS) are 79%, 73%, 69% and 63% respectively. Median follow-up among survivors is 26 months. The frequency and severity of chronic GVHD is remarkably low (5%) compared to historical rates of 40-60% chronic GVHD in HLA-matched PBSC transplantation with conventional calcineurin inhibitor-based immunosuppression. Relapse and non-relapse mortality (NRM) are acceptably low at 19% and 8%, respectively. No NRM occurred in patients <40 years. Updated results will be presented.ConclusionsThe outcomes of recipients of TN-depleted PBSC grafts compare very favorably to published results of HCT for patients with acute leukemia. For example, the 69% incidence of CRFS at 2 years in TN-depleted recipients compares with reported 2-year GRFS rates of 37% and 17% in recipients of allogeneic PBSC from HLA-matched related donors with or without ATG (Kroger et al. NEJM 2016). Our results suggest that TN-depletion of PBSC grafts may reduce the risk of chronic GVHD without negatively impacting other important HCT outcomes. DisclosuresRiddell:Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding; Cell Medica: Consultancy, Honoraria; Adaptive Biotechnologies: Consultancy, Honoraria.

Comparison of Peripheral Blood Stem Cells (PBSC) to Bone Marrow (BM) for T-Replete HLA-Haploidentical Donor Transplantation Using Post-Transplant Cyclophosphamide

T cell-replete haploidentical donor transplants (HAPLO-HCT) using post-transplant cyclophosphamide for control of alloreactivity is now being increasingly utilized. HAPLO-HCTs were originally performed using BM grafts. However, recently, a few single center studies have reported good outcomes using G-CSF mobilized PBSC grafts for HAPLO-HCT. No prospective randomized comparisons of BM to PBSC grafts for HAPLO-HCT have been performed. Therefore, we analyzed outcomes for 687 adults (496 BM, 191 PBSC) who received HAPLO-HCT for hematologic malignancies using post-transplant cyclophosphamide + mycophenolate + calcineurin inhibitor for GVHD prophylaxis between 2009 and 2014 in the United States. The primary outcome was overall survival. The characteristics of recipients of BM and PBSC were similar except BM recipients were older, more likely to have a performance score ≥90, HCT-CI index ≤2, be CMV seronegative, have a lymphoid malignancy and receive reduced-intensity conditioning. Most PBSC transplants occurred between 2012 and 2014. The median follow-up was 35 and 20 months for recipients of BM and PBSC grafts, respectively. Cox regression models were built to study the effect of graft type adjusted for other significant factors on overall mortality, non-relapse mortality, relapse and graft-versus-host disease (GVHD) and outcomes censored at 2-years to accommodate differential follow-up between treatment groups (Table 1). After adjusting for age, CMV serostatus, disease risk index (disease type/disease status for myeloid and lymphoid malignancy and cytogenetic risk for acute leukemia and myelodysplastic syndrome) and transplant conditioning regimen there were no significant differences in risks for overall mortality (HR 1.00, p= 0.98; 2-year overall survival: 54% and 57%) or non-relapse mortality (HR 0.92, p=0.74; 2-year non-relapse mortality: 17% and 16%) after transplantation of BM compared to PBSC, respectively. However, relapse risks were higher after transplantation of BM compared to PBSC (HR 1.49, p=0.009; 2-year relapse: 45% and 28%). Subset analyses explored the effect of graft type separately for myeloablative and reduced intensity conditioning regimen adjusting for age, CMV serostatus and disease risk index. Consistent with the main analysis there were no differences in overall or non-relapse mortality risks and relapse risks were higher with BM compared to PBSC with myeloablative regimens (Table 1). Although this may in part be explained by lower chronic GVHD risks with transplantation of BM grafts, chronic GVHD was not significantly predictive of relapse risk when modeled as a time-dependent covariate (HR= 0.73, p=0.49). Grade II-IV acute GVHD risks (HR 0.45, p<0.001; 22% and 37%), adjusted for conditioning regimen were lower after transplantation of BM compared to PBSC. Chronic GVHD risks adjusted for age and performance score were also lower after transplantation of BM compared to PBSC (HR 0.35, p<0.001; 20% and 41%) but rates of moderate and severe chronic GVHD were not significantly different (28% and 32%). There were no differences in incidence of hematopoietic recovery by graft type. In conclusion, compared to BM grafts HAPLO-HCT with PBSC are associated with similar overall survival and non-relapse mortality risks but lower relapse risks with myeloablative conditioning regimens. Longer follow up is needed to ascertain whether survival differences may occur later. The observed adverse effect of BM grafts on relapse with myeloablative regimens must be studied further in the setting of carefully controlled trials. [Display omitted] DisclosuresCiurea:Cyto-Sen Therapeutics: Equity Ownership; Spectrum Pharmaceuticals: Other: Advisory Board. Hamadani:Takeda: Research Funding. Soiffer:Kiadis: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Juno: Membership on an entity's Board of Directors or advisory committees. Wingard:Ansun: Consultancy; Gilead: Consultancy; Astellas: Consultancy; Fate Therapeutics: Consultancy; Merck: Consultancy.

Infections after Transplantation of Bone Marrow or Peripheral Blood Stem Cells from Unrelated Donors.

Infection is a major complication of hematopoietic cell transplantation. Prolonged neutropenia and graft-versus-host disease are the 2 major complications with an associated risk for infection, and these complications differ according to the graft source. A phase 3, multicenter, randomized trial (Blood and Marrow Transplant Clinical Trials Network [BMT CTN] 0201) of transplantation of bone marrow (BM) versus peripheral blood stem cells (PBSC) from unrelated donors showed no significant differences in 2-year survival between these graft sources. In an effort to provide data regarding whether BM or PBSC could be used as a preferential graft source for transplantation, we report a detailed analysis of the infectious complications for 2years after transplantation from the BMT CTN 0201 trial. A total of 499 patients in this study had full audits of infection data. A total of 1347 infection episodes of moderate or greater severity were documented in 384 (77%) patients; 201 of 249 (81%) of the evaluable patients had received a BM graft and 183 of 250 (73%) had received a PBSC graft. Of 1347 infection episodes, 373 were severe and 123 were life-threatening and/or fatal; 710 (53%) of these episodes occurred on the BM arm and 637 (47%) on the PBSC arm, resulting in a 2-year cumulative incidence 84.7% (95% confidence interval [CI], 79.6 to 89.8) for BM versus 79.7% (95% CI, 73.9 to 85.5) for PBSC, P=.013. The majority of these episodes, 810 (60%), were due to bacteria, with a 2-year cumulative incidence of 72.1% and 62.9% in BM versus PBSC recipients, respectively (P= .003). The cumulative incidence of bloodstream bacterial infections during the first 100days was 44.8% (95% CI, 38.5 to 51.1) for BM versus 35.0% (95% CI, 28.9 to 41.1) for PBSC (P= .027). The total infection density (number of infection events/100 patient days at risk) was .67 for BM and .60 for PBSC. The overall infection density for bacterial infections was .4 in both arms; for viral infections, it was .2in both arms; and for fungal/parasitic infections, it was .04 and .05 for BM and PBSC, respectively. The cumulative incidence of infection before engraftment was 47.9% (95% CI, 41.5 to 53.9) for BM versus 32.8% (95% CI, 27.1 to 38.7) for PBSC (P= .002), possibly related to quicker neutrophil engraftment using PBSC.Infections remain frequent after unrelated donor hematopoietic cell transplantation, particularly after BM grafts.

Peripheral Blood Stem Cells Vs Bone Marrow: Stem Cell Source Comparison for Patients Acute Myeloid Leukemia and Myelodysplastic Syndrome Receiving an Allogeneic Stem Cell Transplantation from a 10/10 Matched Donor. Study from the French Society of Bone Marrow Transplantation and Cell Therapies (SFGM-TC)

Introduction: Peripheral blood stem cells (PBSC) are increasingly used for unrelated donor (UD) hematopoietic stem cell transplantation (HSCT). A recent randomized prospective trial did not detect significant survival differences between PBSC and bone marrow (BM) transplantation from a UD. The use of PBSC reduced the risk of graft failure, whereas BM reduced the risk of chronic graft versus host disease (GVHD) (Anasetti & al, NEJM 2012). However, HLA matching was based on HLA-A, HLA-B, HLA-C &HLA-DRB1 (8/8 but also 7/8), some of the patients (pts) received a reduced intensity conditioning regimen (22%) and diseases consisted of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), but also other hematological malignancies. We thus conducted this study to compare mobilized PBSC with BM for matched 10/10 UD HSCT after standard conditioning regimen (MAC) in pts with AML and MDS only.Patients and methods: We included all consecutive pts in France who received a first HSCT for AML or MDS with PBSC or BM from a matched 10/10 UD after a MAC (fractionated total body irradiation (TBI)-Cyclophosphamide(Cy), n=165 or Endoxan-Cy, n=203) between 2000 and 2013. Clinical data were prospectively collected using ProMISe (Project Manager Internet Server), an internet-based data registry system shared by all centers of the French Society of Bone Marrow Transplantation and Cell Therapies (SFGM-TC). HLA typing data were collected from the SFHI (French Society of Histocompatibility and Immunogenetic) and the ABM (French Biomedical Agency). This study is in accordance with Helsinki declaration for clinical research.Results: We included368 adults pts (221 [60%] received BM; 147 [40%] received PBSC). Median follow-up was of 16.5 months [0-156]. The BM and PBSC groups were well balanced with respect to age, diagnosis, disease risk, use of antithymocyte globulins (ATG) (67 [30%] BM and 52 [35%] PBSC recipients,) and cytomegalovirus (CMV) recipient and donor status. PBSC recipients were more likely to be male and received less TBI-based regimen. GVHD prophylaxis mainly combined cyclosporine A (CSA) and methotrexate (MTX) (82%).The median number of nucleated cell dose infused was higher in the PBSC group compared with the BM group: CD34+ cells, 6.96 x10⁶/kg [1.2-37.8] vs 2,78 x10⁶/kg [0.6-89] p<0.01) and total nucleated cells, 9.8 x10⁸/kg [1.3-663] vs 2.3 x10⁸/kg [0.3-305.3] p<0.01).Two hundred and seven (90%) pts engrafted after BM and 144 (99.3%) after PBSC HSCT (p=0.1). Among pts who received PBSC as compared with those who received BM, the median time to neutrophils engraftment (> 0.5 x 109 /L) was 6 days shorter and 8 days shorter to platelets engraftment (>20x109 /L) (p<0.01).The cumulative incidence (CI) for severe acute GVHD III-IV was 21.1% and 16.3% in the PBSC and the BM group, respectively (p=0.18).CI of chronic GVHD was higher after PBSC (47.1% vs 34.3% for BM, p=0.05). By multivariate analysis, the absence of ATG in the conditioning regimen (HR 0.4 95%CI [0.22-0.72] p<0.01) and PBSC as stem cells source (HR 0.6 95%CI [0.34-0.97] p=0.04) were associated with an increased chronic GVHD.At 2-years, the CI of non relapse related mortality (NRM), relapse as well as disease free survival (DFS) and overall survival (OS) were similar between the 2 groups (Table 1).In multivariate analysis, better OS was associated with complete remission (CR) disease status (HR 0.5 95%CI [0.32-0.69] p<0.01) and pts’s age<38.1 years (HR 0.67 95%CI [0.48-0.93] p=0.02) at time of HSCT, and the use of CSA-MTX as GVHD prophylaxis (HR 0.6 95%CI [0.41-0.95] p=0.03).Conclusion: OS, NRM and relapse rates are similar with PBSC and BM after HLA 10/10 matched UD for AML or MDS using MAC, but engraftment is better with PBSC and the CI of chronic GVHD is lower with BM. Better results are obtained for pts <38 years old with a disease in CR at time of HSCT using CSA-MTX as GVHD prophylaxis. The absence of ATG with PBSC was associated with chronic GVHD. This study thus favors the use of ATG in the setting of matched 10/10 PBSC. However, the role of ATG in the context of BM after HLA 10/10 matched UD MAC HSCT remains unclear and warrants further investigation.Table 1:2-year CI of NRM*, relapse, DFS** and OS***ParametersBM % (95% CI)PBSC % (95%CI)p valueNRM23 (20-26)18 (15-21)0.8Relapse30 (27-33)28 (25-31)0.83DFS47.1 (44-51)54.4 (50-58)0.2OS54 .4 (50.8-57.9)60.2 (55.7-64.6)0.31*NRM: non-relapse mortality**DFS: disease free survival***OS: overall survival DisclosuresNo relevant conflicts of interest to declare.