Mismatched Family Donors Research Articles

Outcomes of hematopoietic stem cell transplantation in 813 pediatric patients with Fanconi anemia

AbstractAllogeneic hematopoietic stem cell transplantation (HSCT) is the only established curative option for Fanconi anemia (FA)–associated bone marrow failure (BMF)/aplastic anemia (AA) and acute myeloid leukemia (AML)/myelodysplastic syndrome (MDS). We performed a retrospective multicenter study on 813 children with FA undergoing first HSCT between 2010 and 2018. Median duration of follow-up was 3.7 years. Median age at transplant was 8.8 years (IQR, 6.5-18.1). Five-year overall survival (OS), event-free survival (EFS), and graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS) were 83% (95% confidence interval [CI], 80-86), 78% (95% CI, 75-81), and 70% (95% CI, 67-74), respectively. OS was comparable between matched family donor (MFD; n = 441, 88%) and matched unrelated donor (MUD; n = 162, 86%) and was superior to that of mismatched family donor (MMFD) or mismatched unrelated donor (MMUD; n = 144, 72%) and haploidentical donor (HID; n = 66, 70%; P < .001). In multivariable analysis, a transplant indication of AML/MDS (vs AA/BMF), use of MMFD/MMUD and HID (vs MFD), and fludarabine-cyclophosphamide (FluCy) plus other conditioning (vs FluCy) independently predicted inferior OS, whereas alemtuzumab vs antithymocyte globulin was associated with better OS. Age ≥10 years was associated with worse EFS and GRFS. Cumulative incidences (CINs) of primary and secondary graft failure were 2% and 3% respectively. CINs of grade 3 to 4 acute GVHD and chronic GVHD were 12% and 8% respectively. The 5-year CIN of secondary malignancy was 2%. These data suggest that HSCT should be offered to patients with FA with AA/BMF at a younger age in the presence of a well-matched donor.

CD3+TCRαβ/CD19+-Depleted Mismatched Family or Unrelated Donor Salvage Stem Cell Transplantation for Graft Dysfunction in Inborn Errors of Immunity

A minority of children experience significant graft dysfunction after an allogeneic hematopoietic stem cell transplant (HSCT) for inborn errors of immunity (IEI). The optimal approach to salvage HSCT is unclear with respect to conditioning regimen and stem cell source. This single-centre retrospective case series reports the outcomes of salvage CD3+TCRαβ/CD19 depleted mismatched family or unrelated donor stem cell transplantation (TCRαβ-SCT) between 2013 - 2022 for graft dysfunction in 12 children with IEI. Outcomes of interest were overall survival (OS), event free survival (EFS), graft-versus-host disease (GvHD)-free and event-free survival (GEFS), toxicities, GvHD, viremia and long-term graft function. A retrospective audit of patients who underwent second CD3+TCRαβ/CD19 depleted mismatched donor graft using Treosulfan-based reduced toxicity myeloablative conditioning. Median age at first HSCT was 8.76 months (range, 2.5 months - 6 years) and at second TCRαβ-SCT was 3.6 years (1.2 - 11 years). Median interval between first and second HSCT was 1.7 years (3 months - 9 years). The primary diagnoses were: severe combined immunodeficiency (SCID) (n=5) and non-SCID IEI (n=7). The indications for second HSCT were: primary aplasia (n=1), secondary autologous reconstitution (n=6), refractory aGVHD (n=3) and secondary leukemia (n=1). Donors were either haploidentical parental donors (n=10) or mismatched unrelated donors (n=2). All received TCRαβ/CD19-depleted-PBSC with a median CD34+ cell dose of 9.3 × 106/kg (2.8-32.3 × 106/kg) and a median TCRαβ+ cell dose of 4 × 104/kg (1.3-19.2 × 104/kg). All engrafted with median days to neutrophil and platelet recovery of 15 (12-24) and 12 (9-19). One developed secondary aplasia and one had secondary autologous reconstitution, but both underwent a successful third HSCT. Four (33%) had grade II aGvHD and none had grade III-IV aGvHD. None had cGvHD but one developed extensive cutaneous cGVHD after third HSCT using PBSC and ATG. Nine (75%) were noted to have at least one episode of blood viremia with HHV6 (n=6, 50%), adenovirus (n=6, 50%), EBV (n=3, 25%) or CMV (n=3; 25%). Median duration of follow-up was 2.3 years (range: 0.5 - 10 years) and the 2-year OS, EFS and GEFS were 100% (95% confidence interval, 0-100%), 73% (37-90%) and 73% (37%-90%) respectively. TCRαβ-SCT from mismatched family or unrelated donors, using a chemotherapy only regimen, is a safe alternative donor salvage transplant strategy for second HSCT in patients without a suitably matched donor.

Hypomorphic RAG deficiency: impact of disease burden on survival and thymic recovery argues for early diagnosis and HSCT

AbstractPatients with hypomorphic mutations in the RAG1 or RAG2 gene present with either Omenn syndrome or atypical combined immunodeficiency with a wide phenotypic range. Hematopoietic stem cell transplantation (HSCT) is potentially curative, but data are scarce. We report on a worldwide cohort of 60 patients with hypomorphic RAG variants who underwent HSCT, 78% of whom experienced infections (29% active at HSCT), 72% had autoimmunity, and 18% had granulomas pretransplant. These complications are frequently associated with organ damage. Eight individuals (13%) were diagnosed by newborn screening or family history. HSCT was performed at a median of 3.4 years (range 0.3-42.9 years) from matched unrelated donors, matched sibling or matched family donors, or mismatched donors in 48%, 22%, and 30% of the patients, respectively. Grafts were T-cell depleted in 15 cases (25%). Overall survival at 1 and 4 years was 77.5% and 67.5% (median follow-up of 39 months). Infection was the main cause of death. In univariable analysis, active infection, organ damage pre-HSCT, T-cell depletion of the graft, and transplant from a mismatched family donor were predictive of worse outcome, whereas organ damage and T-cell depletion remained significant in multivariable analysis (hazard ratio [HR] = 6.01, HR = 8.46, respectively). All patients diagnosed by newborn screening or family history survived. Cumulative incidences of acute and chronic graft-versus-host disease were 35% and 22%, respectively. Cumulative incidences of new-onset autoimmunity was 15%. Immune reconstitution, particularly recovery of naïve CD4+ T cells, was faster and more robust in patients transplanted before 3.5 years of age, and without organ damage. These findings support the indication for early transplantation.

The results of ten years’ experience in allogeneic hematopoietic stem cell transplantation at the Russian Children’s Clinical Hospital

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a common treatment for a large number of pediatric diseases. Treatment planning is based on a careful selection of patients and donors, taking into account factors contributing to a successful outcome. The aim of our study was to analyze the results of 10 years’ experience in allo-HSCT gained at the Department of Bone Marrow Transplantation of the Russian Children's Clinical Hospital of the N.I. Pirogov Russian National Research Medical University. We retrospectively analyzed 506 patients who had undergone their first allo-HSCTs between January 2010 and December 2020. The study was approved by the Independent Ethics Committee and the Scientific Council of the N.I. Pirogov Russian National Research Medical University of Ministry of Healthcare of the Russian Federation. We included 243 patients who had received allo-HSCT before December 2015 and 263 patients who had received allo-HSCT after January 2016. The gender distribution was 60.1% male (n = 304) and 39.9% female (n = 202). The median age was 7.13 years. Allo-HSCT recipients were divided into two groups: 236 children with non-malignant disease, 270 children with malignant disease. In the malignant group, 89 patients were in first complete remission (CR1), 92 were in second complete remission (CR2), and 20 were in third complete remission (CR3) and beyond; 63 patients had active disease (AD); 6 patients received no prior treatment. Two hundred and twenty patients underwent allo-HSCT from a fully matched family donor (MFD), 172 from a matched unrelated donor (MUD), 33 from a mismatched unrelated donor (MMUD) and 81 from a haploidentical (mismatched) family donor (MMFD). Two hundred and eighty-eight patients received bone marrow as a stem cell source, 208 received peripheral blood stem cells; 10 transplants were performed using umbilical cord blood stem cells. The 5-year overall survival (OS) in the entire cohort was 71.34 %. The 5-year OS in the patients who had undergone allo-HSCT between 2016 and 2020 was higher (p = 0.0014). After 2015, the rates of primary graft failure, the incidence of grade III–IV acute “graft-versus-host” disease (GVHD), and recurrence rates were significantly lower. No difference in the incidence of grade III–IV acute GVHD (p = 0.494) and OS rates (p = 0.138) was seen between different sources of hematopoietic stem cells in the patients who received an HLA-compatible transplant (MFD, MUD). Chronic GVHD was significantly dependent on the severity of acute GVHD and donor type. The 3-year OS rate for the patients in CR1, CR2, ≥ CR3, and AD was 84.4 %, 60.5 %, 56.8 %, and 46 % (p = 0.0034), respectively. The relapse rate of the patients in any remission was lower than of those in active disease (p = 0.015). The transplantation-related mortality in the first 100 days after allo-HSCT was 6.92% (n = 35). The patients who had undergone allo-HSCT after 2015 had lower rates of primary graft failure, a decreased incidence of severe GVHD, improved OS and relapse-free survival rates. The frequency of grade III–IV acute GVHD strongly correlated with HLA compatibility. Chronic GVHD was less frequent in MFD recipients. The risk of chronic GVHD increased with the severity of acute GVHD. The HLA mismatch between a donor and a recipient was associated with a decrease in OS. With each subsequent remission, the OS rate decreased. The risk of recurrence was higher in the patients transplanted in active disease. The results of this study can be used in clinical practice to plan therapy, choose an optimal donor, and develop strategies for the prevention and treatment of complications.

Hematopoietic stem cell transplantation for Wiskott-Aldrich syndrome: an EBMT Inborn Errors Working Party analysis

AbstractAllogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative treatment for patients affected by Wiskott-Aldrich syndrome (WAS). Reported HSCT outcomes have improved over time with respect to overall survival, but some studies have identified older age and HSCT from alternative donors as risk factors predicting poorer outcome. We analyzed 197 patients undergoing transplant at European Society for Blood and Marrow Transplantation centers between 2006 and 2017 who received conditioning as recommended by the Inborn Errors Working Party (IEWP): either busulfan (n = 103) or treosulfan (n = 94) combined with fludarabine ± thiotepa. After a median follow-up post-HSCT of 44.9 months, 176 patients were alive, resulting in a 3-year overall survival of 88.7% and chronic graft-versus-host disease (GVHD)-free survival (events include death, graft failure, and severe chronic GVHD) of 81.7%. Overall survival and chronic GVHD-free survival were not significantly affected by conditioning regimen (busulfan- vs treosulfan-based), donor type (matched sibling donor/matched family donor vs matched unrelated donor/mismatched unrelated donor vs mismatched family donor), or period of HSCT (2006-2013 vs 2014-2017). Patients aged <5 years at HSCT had a significantly better overall survival. The overall cumulative incidences of grade III to IV acute GVHD and extensive/moderate/severe chronic GVHD were 6.6% and 2.1%, respectively. Patients receiving treosulfan-based conditioning had a higher incidence of graft failure and mixed donor chimerism and more frequently underwent secondary procedures (second HSCT, unconditioned stem cell boost, donor lymphocyte infusion, or splenectomy). In summary, HSCT for WAS with conditioning regimens currently recommended by IEWP results in excellent survival and low rates of GVHD, regardless of donor or stem cell source, but age ≥5 years remains a risk factor for overall survival.

Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation from HLA-Identical Siblings Versus Unmanipulated Haploidentical Donors in Relapsing or Refractory Acute Myeloid Leukemia: A Retrospective Study from the ALWP of the EBMT

▪Introduction: Primary refractory or relapsing acute myeloid leukemia (R/R-AML) has very poor prognosis. Allogeneic hematopoietic stem cell transplantation (HSCT) may be the only chance of cure. Therefore a suitable donor should be rapidly searched for, in this setting. In those patients (pts) lacking an HLA-matched sibling donor (MSD), mismatched family donor (haploidentical, Haplo) may represent a valid and rapidly available option.Methods: Herein, we compared the outcomes of pts with R/R-AML undergoing first HSCT from either a MSD (n=1654) or Haplo (n=389) in the period 2007-2015. The Haplo group included pts receiving a T-repleted graft with post-transplant cyclophosphamide (PTCY, n=278), in vivo T-cell depletion (TCD, n=95), or both (n=16).Results: Median age at HSCT was 52 (range 18-74) years. Median follow-up was 16 and 22 months for MSD and Haplo recipients, respectively (p=0.11). At time of HSCT, 41% and 56% presented a primary refractory AML in Haplo and MSD groups, respectively (p<0.01). Compared to MSD, Haplo HSCT were performed more recently (median year 2013 versus 2011, p<0.01) with a higher number of pts having a poor Karnofsky performance status (22% versus 16%, p<0.01) and a positive serology for CMV (83% versus 71%, p<0.001) at time of HSCT, respectively. The latter also had more frequently undergone a previous autologous HSCT (8% vs 3%, p<0.01), had a longer interval from diagnosis to HSCT (7 versus 5 months, p<0.01), received more frequently bone marrow as stem cell source (47% vs 8%, p<0.01), a reduced intensity conditioning regimen (50% vs 43%, p<0.03), and a graft from a male donor (59% versus 53%, p<0.03) as compared to MSD recipients. Compared to Haplo, cumulative incidence (CI) of neutrophil engraftment was higher (93% versus 83%, p<0.01) and associated to a shorter median time to engraftment (15 versus 18 days, p<0.01) in MSD recipients. According to donor type, no differences were found in univariate analysis for the CI of grade II-IV acute graft-versus host disease (aGVHD)(28% versus 27%, p=0.37), while a lower CI of chronic GVHD (cGVHD) (27% versus 42%, p<0.01) and extensive cGVHD (12% and 19%, p<0.01) was observed in HSCT from Haplo compared to MSD, respectively. At two years, overall survival (OS) was 25% and 32% (p<0.01), leukemia-free survival (LFS) 19% and 27% (p<0.01) and GVHD/relapse-free survival (GRFS) 18% and 26% (p<0.01) in HSCT from Haplo and MSD, respectively. Relapse incidence (RI) was similar following HSCT from Haplo and MSD (50% vs 51%, p=0.60), while non-relapse mortality (NRM) was higher for Haplo transplants (31% vs 22% in HSCT from MSD, p<0.001), respectively. In a multivariate analysis adjusted for the differences between the two groups, Haplo HSCT was associated with lower OS (HR 1.19, p<0.04), LFS (HR 1.17, p<0.05) and GRFS (HR 1.22, p<0.02). Higher grade II-IV aGVHD was observed in Haplo recipients. Neither cGVHD (any grade) nor RI differed according to donor type (p=ns). Compared to MSD, Haplo recipients experienced a higher NRM (HR 1.4, p<0.02) mainly related to a higher incidence of infections (41% versus 25%, p<0.01). Regardless of donor type, age as a continuous variable was associated with lower RI (HR 0.99, p<0.01), lower OS (HR 1.01, p<0.01) and higher NRM (HR 1.02, p<0.01). The use of peripheral blood as stem cell source was independently associated with a higher risk of cGVHD (HR 1.64, p<0.01).Conclusions: Our results indicate that for pts with R/R-AML outcome is better with HSCT from a MSD compared to unmanipulated Haplo donor, mainly due to the higher NRM associated with transplants from Haplo and most probably related to a higher incidence of infections and grade II-IV aGVHD. Chronic GVHD as well as RI are similar, indicating once again that despite the broader HLA disparities with Haplo HSCT the graft versus leukemia effect is probably not stronger than after HSCT from MSD (Ringden O, on behalf of the ALWP; Leukemia 2016). In the absence of a MSD, Haplo HSCT may represent a valid alternative, with nearly one quarter of the R/R-AML pts surviving at 2 years from transplant. Future goals in the Haplo setting should be to reduce NRM and rate of infections in order to further improve outcomes. DisclosuresCiceri:GSK: Other: B-thalassemia gene therapy was developed by Fondazione Telethon and Ospedale San Raffaele and has been inlicenced by GSK that provides funding for the clinical trial, Research Funding. Mohty:Sanofi: Honoraria, Speakers Bureau.

Donor EBV-Positive Serostatus Increases the Risk of Chronic GVHD in Patients with Myeloid and Lymphoid Malignancies Other Than Acute Leukemia: Infectious Diseases Working Party EBMT Study

BACKGROUND: In patients with acute leukemia (AL), donor EBV (Epstein-Barr Virus) seropositive status significantly increases the risk of development of acute and chronic GVHD after allo-HSCT, while it has no influence on other transplant outcomes (OS, RFS, RI, NRM) (Styczynski et al , J Clin Oncol, 2016). No data are available on the impact of EBV serostatus on transplant outcomes in patients with other hematological malignancies.OBJECTIVE: We analyzed the influence of the recipient's (R) and donor's (D) EBV serostatus on transplant outcomes (overall survival, OS; relapse-free survival, RFS; relapse incidence, RI; non-relapse mortality, NRM; acute graft-versus-host disease, aGVHD; chronic graft-versus-host disease, cGVHD) in patients with myeloid and lymphoid malignancies other than AL undergoing allo-HSCT.PATIENTS AND METHODS: 12,931 allo-HSCTs performed between 1997 and 2016 for myeloid (58.1%) or lymphoid malignancies (41.9%), other than AL, with PB (76%) or BM±PB (24%) as a stem cell source were included in this retrospective Registry megafile IDWP EBMT study.RESULTS:DEMOGRAPHICS : 48% had HSCT from a matched family donor, 4.2% from a mismatched family donor, and 47.8 from an unrelated donor. T-cell depletion was performed in vivo in 58.4%, and ex vivo in 7.9% patients. Conditioning regimen was myeloablative in 41.3%, RIC in 58.7%. Median follow-up was 4.7 years. TRANSPLANT OUTCOMES : EBV-seropositive patients receiving grafts from EBV-seropositive donors (EBV R+/D+ transplants) had worse transplant outcomes in comparison to EBV-seronegative patients receiving grafts from EBV-seronegative donors (EBV R-/D-): lower OS (59.6% vs 65.9%), lower RFS (51.1% vs 57.5%), higher incidence of chronic GVHD (49.5% vs 41.8%), and higher incidence of de novo chronic GVHD (30.5% vs 24.0%). No significant differences were found for: RI, NRM, and acute GVHD (Table 1). MULTIVARIATE ANALYSIS : Allo-HSCT from EBV-seropositive donors had higher risk of development of cGVHD (HR=1.13; p=0.0096). When 4 subgroups (R-/D-, R-/D+, R+/D-, R+/D+ EBV serology) were analyzed, the risk of cGVHD was higher for EBV R-/D+ (HR=1.22; p=0.0395), R+/D- (HR=1.21; p=0.0375), and for R+/D+ (HR=1.28; p=0.0013) when compared to R-/D- transplants. On the other hand, R/D EBV serostatus had no significant impact on OS, RFS, RI, NRM and development of acute GVHD. Finally, since the R-/D- combination patients were more likely to be children than R+/D+, this could explain the effect in univariate analysis on OS and RFS while the chronic GVHD effect was independent of age.CONCLUSIONS: Allo-HSCT from EBV-seropositive donors are at 13% higher risk of chronic GVHD in patients with myeloid and lymphoid malignancies other than AL. [Display omitted] DisclosuresPetersen:Sanofi: Membership on an entity's Board of Directors or advisory committees. Leblond:SERVIER: Honoraria, Membership on an entity's Board of Directors or advisory committees; GILEAD: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; JANSSEN: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; ABBVIE: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; ROCHE: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Honoraria; NOVARTIS: Honoraria, Membership on an entity's Board of Directors or advisory committees. Michallet:medac GmbH, Wedel, Germany: Honoraria, Other: Travel grants. Kröger:Janssen Global Services, LLC: Speakers Bureau; Amgen Inc.: Speakers Bureau; Novartis AG: Research Funding; RIEMSER Pharma: Research Funding; Neovii Pharmaceuticals AG: Speakers Bureau; Novartis AG: Speakers Bureau; Sanofi: Speakers Bureau.

Long Term Follow-Up of the Patients with Severe Combined Immunodeficiency After Hematopoietic Stem Cell Transplantation: A Single-Center Study

ABSTRACT Background We aimed to evaluate hematopoietic stem cell transplantation (HSCT) related outcomes of patients with severe combined immunodeficiency (SCID). Methods We retrospectively collected data from SCID patients who were diagnosed, followed up and survived at least 2 years after HSCT. Results Forty four SCID patients were included in the study. Median age of HSCT and follow-up period after HSCT were 7.1 months and 8.7 years, respectively. Human leukocyte antigen (HLA) identical donors were used in 77.3% (n = 34) of the patients (23 siblings, six fathers, two mothers, three extended family donors), HLA 1–2 mismatched family donors in 11.3% (n = 5), and haploidentical family donors in 11.3% (n = 5). CD3 and CD19 counts were normal in more than 90% and in 45.4% at last follow-up, respectively. Intravenous immunoglobulin (IVIG) could be stopped in 72.7% (n = 32) after HSCT. B+ SCID patients had better CD19 counts than B- (p < .001). T cell numbers, lymphocyte proliferation, IVIG need, immunoglobulin levels, antibody responses did not differ among B- and B+ immunophenotypes. Acute graft-versus-host disease (GVHD) was less in bone marrow transplanted patients (19.4%) than peripheral stem cell (58.3%) transplanted ones (p = .024). There was no correlation between age at transplantation and immune reconstitution. At the last follow-up, 70.2% and 78.3% of the patients had body weight and height above 3rd percentile, respectively. Conclusion The immune reconstitution and the growth were normal in the majority of SCID patients after HSCT. It may be rational to use bone marrow instead of peripheral stem cell, as acute GVHD was less in bone marrow transplanted patients.

Allogeneic hematopoietic stem cell transplantation from family members other than HLA-identical siblings over the last decade (1991-2000)

AbstractThe reported outcome of hematopoietic stem cell transplantation (HSCT) from HLA-mismatched family members has been inconsistent. The object of this study was to evaluate the true impact of HLA-mismatch by using recent data from a homogenous population, excluding HSCT procedures that used graft manipulations, and by considering genotypic matching. Clinical data of 2947 patients who underwent allogeneic HSCT for leukemia or myelodysplastic syndrome were extracted from the database of the Japan Society for Hematopoietic Cell Transplantation. The main outcome measures were survival and the incidence of graft-versus-host disease (GVHD). The presence of serologic HLA-mismatch, higher age, and high-risk disease were identified as independent risk factors for both shorter survival and the development of grade III to IV acute GVHD. The impact of HLA-mismatch on survival was more relevant in standard-risk patients. These findings persisted when we used genotypic HLA matching. Survival after one-locus–mismatched HSCT was equivalent to that after HLA-matched unrelated HSCT. We concluded that when a one-locus–mismatched family donor is available for high-risk patients, immediate HSCT using this donor is warranted. In standard-risk patients, however, survival after one-locus–mismatched HSCT is significantly shorter than that after HLA-matched HSCT, and the indications for HSCT should be considered carefully.

Prognostic impact of Epstein-Barr virus serostatus in patients with nonmalignant hematological disorders undergoing allogeneic hematopoietic cell transplantation: the study of Infectious Diseases Working Party of the European Society for Blood and Marrow Transplantation

AbstractBackgroundIn patients with acute leukemia, lymphoma and chronic malignancies, donor and/or recipient Epstein-Barr virus (EBV) seropositive status increases the risk of development of chronic graft-versus-host disease (cGVHD) after allo-hematopoietic cell transplantation (allo-HCT), while it has no influence on other transplant outcomes. No data are available on the impact of EBV serostatus on transplant outcomes in patients with nonmalignant hematological disorders.ObjectiveWe analyzed the influence of the recipient's (R) and donor's (D) EBV serostatus on transplant outcomes (overall survival (OS); relapse-free survival (RFS); relapse incidence (RI); nonrelapse mortality (NRM); acute graft-versus-host disease (aGVHD); cGVHD) in patients with nonmalignant hematological disorders undergoing allo-HCT.Patients and MethodsA total of 2,355 allo-HCTs performed between 1997 and 2016 for acquired bone marrow failure or hemoglobinopathies were included in this retrospective Registry megafile Infectious Diseases Working Party of the European Society of Blood and Marrow Transplantation (IDWP-EBMT) study.ResultsDemographics: The median age of recipient was 17.7 years (range: 0–77), and 50.8% were children. 79.0% of recipients and 75.4% of donors were EBV-seropositive. 67.8% had HCT from a matched family donor, 4.6% from a mismatched family donor, and 27.6% from an unrelated donor (UD). T-cell depletion was performed in vivo and ex vivo in 82.2% and 6.6% of patients, respectively. Conditioning regimen was myeloablative in 63.7% and reduced intensity conditioning (RIC) in 36.3% of patients. The median follow-up was 4.7 years. Transplant outcomes: EBV-seropositive recipients in comparison with EBV-seronegative recipients had lower OS (85.4% vs. 88.4%, p = 0.035) and higher NRM (10.0% vs. 6.4%, p = 0.018). No other significant differences were found for: RI, RFS, and aGVHD or cGVHD with respect to EBV pretransplant serostatus donor and/or recipient. Multivariate analysis: A trend toward higher risk of development of cGVHD (HR = 1.31; p = 0.081) and better survival (HR = 0.78; p = 0.087) in allo-HCT from EBV-seropositive donors was found. Allo-HCT in EBV-seropositive recipients had a trend toward lower risk of development of cGVHD (HR = 0.75; p = 0.065). When four subgroups (R−/D−, R−/D+, R+/D−, R+/D+ EBV serology) were analyzed, the EBV serostatus had no significant impact on OS, RFS, RI, NRM and development of aGVHD or cGVHD.ConclusionsAllo-HCT from EBV-seropositive versus EBV-seronegative donors are at 31% higher risk of cGVHD in patients with nonmalignant hematological disorders undergoing allo-HCT; however this difference is nonsignificant in multivariate analysis.

Outcome of Allogeneic Hematopoietic Stem Cell Transplantation in Children and Adolescents with GATA2-Related Myelodysplastic Syndrome

Background GATA2 deficiency is an inherited immunodeficiency and predisposition syndrome with a high risk of developing myelodysplastic syndrome (MDS) early in life. Allogeneic hematopoietic stem cell transplantation (HSCT) is presently the only curative therapy for affected patients (pts), but to date there has been no larger study examining in detail outcomes after HSCT for GATA2-related pediatric MDS. Here we report the results of an analysis of pts with a germline GATA2 mutation undergoing HSCT for a diagnosis of MDS enrolled in the registry of the European Working Group of MDS in Childhood (EWOG-MDS). Patients and transplantation procedure Of the 87 pts with GATA2 deficiency registered before the age of 18 years, 66 underwent HSCT between 01/1997 and 11/2018. One pt had to be excluded from the analysis due to lack of data. The 65 remaining pts (34 males/31 females) were transplanted at a median age of 13.5 (4.6-19.9) years. Twenty-seven pts were transplanted for refractory cytopenia of childhood (RCC), while 38 pts had advanced disease. The highest bone marrow (BM) blast percentage prior to HSCT was 5-19% (n=23), 20-29% (n= 9) or &gt;30% blasts (n=5); in one pt with myelofibrotic MDS a blast count was not attainable. Karyotypes included monosomy 7 (n=44), der (1;7) (n=4), trisomy 8 (n=4), random aberration (n=1) or a normal karyotype (n=12). Five of the 38 pts with an increased blast percentage had received intensive AML-type therapy prior to HSCT. Pts were grafted from a matched sibling donor (MSD; n=17), unrelated donor (UD; n=40) or a mismatched family donor (MMFD; n=8). The stem cell source was BM (n=37), peripheral blood (n=27) or cord blood (n=1). Pts were prepared with a busulfan-based (n=35), treosulfan-based (n=21), total body irradiation-based (n=5) or an alternative conditioning regimen (n=4). Results At 5 years the probability of overall survival (pOS) and disease-free survival (DFS) was 0.74 [0.62-0.86] and 0.69 [0.57-0.81], respectively, non-relapse mortality was 0.15 [0.08-0.27] and the cumulative incidence of relapse was 0.16 [0.09-0.29]. All pts engrafted initially. The cumulative incidence of acute graft versus host disease (GVHD) grade II-IV and III-IV was 0.34 [0.24-0.48] and 0.12 [0.06-0.24], respectively, and of overall and extensive chronic GVHD 0.25 [0.16-0.39] and 0.08 [0.03-0.20]. The most common post-transplant infections were viral (39 of the 43 pts with infections) with one pt each with EBV-related post-transplant lymphoproliferative disease and primary CMV disease. There were no mycobacterial infections. The most common non-infectious complications were hepatobiliary (13 pts, including 3 with veno-occlusive disease) and pulmonary (10 pts, 5 of whom had been prepared with a busulfan-based conditioning regimen). Pts with &gt;20% BM blasts showed a trend towards a poorer DFS (0.52 [0.24-0.80]) compared to pts with 5-19% blasts (0.72 [0.53-0.91]) or pts with RCC (0.80 [0.64-0.96]; p=0.15). Examining the influence of karyotype in pts with RCC, there were a total of 2 relapses and 3 deaths (1 after relapse) among the 12 pts with monosomy 7, while there was one event among the 15 RCC pts with a normal karyotype (n=10, 1 death), trisomy 8 (n=3), der (1;7) (n=1) or random aberration (n=1). Limiting the analysis to 9/10 or 10/10 HLA matched-donors, DFS was comparable for pts transplanted from an UD (0.73 [0.55-0.91]) versus a MSD (0.82 [0.64-1.00]). Of the 8 pts transplanted from a MMFD, one patient died after secondary graft failure. No major difference in outcome was seen according to age at HSCT, gender, time from diagnosis to HSCT or stem cell source. Of the five pts who had received AML-type therapy prior to HSCT, three died of a transplant-related cause or relapse. Conclusions and perspectives In summary, HSCT resulted in a pOS of 0.74 in this cohort of children and adolescents with GATA2 deficiency and MDS. Pts with increased blasts had a tendency towards poorer outcomes. The high risk of developing advanced MDS and the better outcome in early stages of the disease indicates that HSCT should be performed early in the clinical course of children diagnosed with GATA2 deficiency and MDS. Of note, there was no indication of excessive toxicity, disease-associated comorbidities or an increased risk of GVHD. The HSCT outcomes of children and adolescents with MDS and GATA2 deficiency are similar to what has been previously published for pts transplanted for MDS in the absence of GATA2 germline disease. Disclosures Bader: Amgen (Brasil), Novartis: Consultancy, Speakers Bureau; Celgene: Consultancy; Medac: Patents &amp; Royalties, Research Funding; Riemser, Neovii: Research Funding. Locatelli:Miltenyi: Honoraria; bluebird bio: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees. Niemeyer:Celgene: Consultancy.

PF636 NATURAL KILLER CELL ALLOREACTIVE HAPLOIDENTICAL STEM CELL TRANSPLANTATION FOR MULTIPLE MYELOMA PATIENTS

Background:Notwithstanding the progress made over the past years in survival of Multiple Myeloma (MM) patients, MM remains incurable. Haploidentical bone marrow transplantation (Haplo‐BMT) is a treatment option with curative potential. Haplo‐BMT already has shown clinical results however, only in a minority of MM patients. We hypothesize that this observation might be due to differences in natural killer (NK) cell alloreactivity and in this study we set out to prospectively investigate if NK cell mismatch is relevant for the outcome of haplo‐BMT.Aims:The aim of this prospective phase 2 study is to evaluate if KIR‐ligand mismatched haplo‐BMT with post‐transplant cyclophosphamide will improve progression free survival in poor risk MM patients.Methods:Poor risk MM patients, aged &lt; 66 years were enrolled if they were responsive to their last line of therapy. Poor risk was defined as high‐risk cytogenetics, relapse within a year after autologous SCT, or treatment with threeor more previous lines of therapy. A prerequisite of enrolment was the possibility of an NK cell mismatch and availability of a mismatched family donor. Patients were excluded if donor‐specific HLA‐antibodies were present. Patients receive a haplo‐BMT with a non‐myeloablative conditioning regimen and post‐transplant cyclophosphamide. Primary endpoint is PFS at 1,5 years. Secondary endpoints are engraftment, bone marrow reconstitution, NK cell reconstitution, graft versus host disease (GvHD), infections and non‐relapse mortality (NRM).Results:In total 12 poor risk patients were included in the study of which 10 could be evaluated for the primary end point. Graft failure (1/12) and disease progression before transplant (1/12) rendered the remaining two patients not evaluable. At this interim analysis, 5 patients have reached 1,5 years follow up. Off all included patients mortality was 4/12 (33%), only 2 patients were in remission at death (NRM 17%). Of the 8 ‐ for the primary endpoint evaluable‐ patients 7 patients relapsed within 1,5 years. The last included patient is still in a stringent very good partial response at day 120. Average time of relapse is 141 days (30–360 days). Though relapsed, only 4/7 patients had to start anti‐myeloma treatment (time to next treatment 188 days). Of the 11 engrafted patients, average time to neutrophil recovery was 18 days (12–30 days) and average time to platelet recovery was 31 days (23–49 days). At day 30, all of the 9 analyses patients showed NK cell recovery, though with an immature phenotype (NKG2A+, KIR−). At day 60 in both the peripheral blood as well as bone marrow, mature NK cells (KIR+) could be identified. Of the engrafted patients 7 developed aGvHD, 55% grade I‐II and 9% grade II‐IV. Four patients developed cGvHD, all 36% grade I‐II. Treatment related mortality was 25%, which was in all cases due to infections. Infections were common post‐transplant and 45% of patients suffered from severe infections.Summary/Conclusion:The majority of patients showed early disease progression after mismatched haplo‐BMT. We predefined that with a PFS of 25% at 1,5 years we would qualify this treatment option successful. With only one patient still in remission this goal will not be achieved and we hypothesize that the late reconstitution of functional mature NK cells is responsible for the lack of response. Though, not yet successful, we show that mismatched haplo‐BMT in MM patients is feasible, in terms of engraftment and late NK cell reconstitution, save and forms a possible platform for future immunotherapeutic strategies.

Prophylaxis of Chemotherapy-Induced Nausea and Vomiting with Fosaprepitant and Granisetron in Pediatric Patients after Allogeneic HSCT

1. BackgroundChemotherapy-induced nausea and vomiting (CINV) is a feared and burdensome complication after emetogenic chemotherapy (EC), especially in pediatric patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). Antiemetic prophylaxis (AEP) is thus a substantial factor in the transplantation management. Guidelines recommend a comprehensive AEP with NK1R-antagonists (neurokinin-1 receptor), 5-HT3R-antagonists (5-hydroxytryptamine-3 receptor), and corticosteroids. The water-soluble aprepitant derivative fosaprepitant (NK1R-antagonist) was shown to be highly effective in adult patients with moderately to highly EC when combined with granisetron (5-HT3R-antagonist). There is very little experience with fosaprepitant in pediatric patients.2. Patients and MethodsIn this single-center retrospective study, 80 pediatric patients during allogeneic HSCT who received AEP either with intravenous fosaprepitant and granisetron (fosaprepitant group; FG) or a standard prophylaxis regimen with granisetron two times per day(historical control group; CG) were analyzed for safety and efficacy of the prophylaxis regimen. Efficacy of the two AEP regimen was evaluated comparing the vomiting frequency, percentages of patients vomiting and the need for rescue medication (dimenhydrinate) during the acute (<24h) and the delayed (24-120h) CINV phase in both groups. Safety was evaluated comparing drug-related clinical and laboratory-chemical side-effects (exanthema, gastrointestinal symptoms, sweating, liver and kidney parameters, and electrolytes). Exclusion criteria were vomiting or receiving antiemetic medication within 48 hours before the start of antiemetic prophylaxis.3. ResultsA total of 80 pediatric patients with a median age of 9 years (range 2-17 years) who underwent allogeneic HSCT between 2015 and 2018 were consecutively enrolled and analyzed. Patients were transplanted for the treatment of acute leukemia (acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), ALL-relapse, AML-relapse; total: 36.5% of the patients), myelodysplastic syndromes (4.8% of the patients) solid tumors and lymphoma (neuroblastoma, brain tumor, non-Hodgkin's lymphoma, Hodgkin's lymphoma; 44.9% of the patients), and non-malignant hematopoietic diseases (thalassemia major, sickle cell anemia; 13.8% of the patients). The patients received allogeneic grafts from matched unrelated donors (48.4%), matched family donors (16.2%) and mismatched family donors (35.5%). Distribution of the patient characteristics was not significantly different in both study groups (p>0.05).The patients of the FG (n=40; HSCT between 2017 and 2018) received a single dose of fosaprepitant (3.5-4 mg per kg bodyweight (mg/kg); maximum 150 mg; intravenous (IV) infusion) directly before starting the myeloablative conditioning and as PRN (pro re nata) medication every five days after HSCT (same dosage; IV infusion), as well as granisetron (2x20 µg/kg per day; starting on the first day of the conditioning; max. 3 mg; IV infusion <30 min.). The patients of the historical CG (n=40; patients transplanted between 2013 and 2014) received granisetron only at the same dosages. Discontinuation of the antiemetic medication was not necessary for any of the patients (CG and FG). Clinical side-effects and laboratory-chemical changes were not significantly different in both study groups (p>0.05). When compared to the patients of the CG, significantly less patients of the FG experienced vomiting in both, the acute (p<0.001) and the delayed CINV phase (p<0.0001); accordingly, significantly less vomiting events (p<0.0001) were observed during both CINV phases in the FG. Furthermore, the FG received significantly fewer doses of dimenhydrinate in comparison to the CG (p<0.001).4. ConclusionsThe prophylaxis regimen with fosaprepitant in combination with granisetron was safe and more effective in comparison to the standard prophylaxis regimen with granisetron only in pediatric patients undergoing allogeneic HSCT with a myeloablative conditioning. However, larger prospective trials are needed to evaluate these findings.5. KeywordsChemotherapy-induced nausea and vomiting; antiemetic prophylaxis; fosaprepitant; pediatric patients6. AcknowledgmentsThis study was supported by the Stefan-Morsch-Stiftung, Birkenfeld, Germany. DisclosuresSchlegel:Miltenyi Biotec: Patents & Royalties, Research Funding. Seitz:Miltenyi Biotec: Patents & Royalties, Research Funding. Lang:Miltenyi Biotec: Patents & Royalties, Research Funding. Handgretinger:Miltenyi Biotec: Patents & Royalties: Co-patent holder of TcR alpha/beta depletion technologies, Research Funding.

Busulfan/Fludarabine- or Treosulfan/Fludarabine-Based Conditioning Regimen in Patients with Wiskott-Aldrich Syndrome Given Allogeneic Hematopoietic Cell Transplantation — an EBMT Inborn Errors Working Party and Scetide Retrospective Analysis

PV and AL contributed equallyMultiple studies from the EBMT registry and others have shown excellent survival rates after allogeneic haematopoietic stem cell transplantation (HSCT)for Wiskott-Aldrich syndrome (WAS) patients (Ozsahin et al, Blood 2008). The importance of myeloid engraftment for full disease correction has also been demonstrated (Moratto et al, Blood 2011). However, the vast majority of HSCTs in these studies were performed with (oral) busulfan/cyclophosphamide-based conditioning and in the early 2000 years or before. In 2005, the inborn errors working party (IEWP) of EBMT and ESID first recommended busulfan/fludarabine (BuFlu) or treosulfan/fludarabine (TreoFlu) based conditioning for primary immunodeficiencies such as WAS, with some centers deciding to add thiotepa (TT) to the conditioning.We performed a retrospective analysis via the EBMT and SCETIDE registries of WAS patients transplanted between 01/01/20006 and 12/31/2016 with these two regimens. The primary objective was to compare the overall (OS) and event-free survival (EFS) after HSCT with either BuFlu±TT or TreoFlu±TT conditioning. Secondary objectives included the influence of either conditioning regimen on acute and chronic GVHD, the degree of donor chimerism, incidence of secondary procedures after HSCT (2nd HSCT, stem cell boost, DLI, gene therapy or splenectomy) and rates of disease-specific complications after HSCT.At the time of this interim analysis, 174 patients were included, 92 (53%) with BuFlu±TT and 82 (47%) with TreoFlu±TT conditioning with a median age of 1.57 years (range 0.21-29.96) at HSCT and a median follow-up of 32.9 months (range 1.5-128.9). The donor was an HLA-matched sibling (MSD) in 30, a matched related donor (MRD) in 5, a matched unrelated donor (MUD, 9/10 or 10/10) in 105, a mismatched unrelated donor (MMUD, <9/10) in 9 and a mismatched family donor (MMFD) in 25 (18 with ex-vivo T-cell depletion). Stem cell source was bone marrow in 93 (53%), peripheral blood in 62 (36%) and cord blood in 18 (10%). Two year overall survival (OS) of the entire cohort was 88.6% (95% confidence interval 83.5%-93.6%). There was no significant difference in OS between patients treated with BuFlu±TT or TreoFlu±TT conditioning (2-year OS 88.1% vs. 89.5%; log-rank test p=0.7). Patients aged >5 years had a worse OS as compared to those 5 years or younger at HSCT (74.9% vs. 90.8%; log-rank test p=0.005). The type of donor had no influence on OS: 96.4% for MSD/MFD, 86.8% for MUD/MMUD and 87.7% for MMFD (log-rank test p=0.4). Whole blood chimerism was complete (>90% donor) in 60/75 evaluable patients (80%) at last follow-up or before secondary procedure (if a patient had one), 39/40 (98%) in the BuFlu±TT group and 21/35 (60%) in the TreoFlu±TT group. Twenty-six patients required a secondary procedure: stem cell boost in 4 patients, donor lymphocyte infusion in 9, 2nd HSCT in 15 and splenectomy in 1. Twenty-two of these 26 (84.6%) are alive and 14 of 16 with available chimerism data have a complete donor chimerism (>90%donor) at last follow-up. The 2-year cumulative incidence (CI) of secondary procedures was higher at 33.9% in the TreoFlu±TT versus 12.8% in the BuFlu±TT group (Gray's test p=0.017), and 2-year EFS (secondary procedure or death as event) was 61.4% in the TreoFlu±TT and 75.0% in the BuFlu±TT group (log-rank test p=0.2). Grade II-IV acute GVHD had the same incidence in both groups (100 day CI 24.4% vs. 26.3%; Gray's test p=0.849) and chronic GVHD of any grade was borderline more frequent in the TreoFlu±TT group (2 year CI 17.2% vs 6.7%; Gray's test p=0.054). The cumulative incidence of disease-specific complications occurring more than 6 months post HSCT (severe infections, bleeding, autoimmunity) was not different between the two groups (6.5% vs. 6.4%; Gray's test p=0.92). There was no malignancy reported after HSCT except for one EBV-post-transplant lymphoproliferative disorder (PTLD) 2.7 months after HSCT.In summary, HSCT with either BuFlu±TT or TreoFlu±TT conditioning reliably cures almost 90% of patients with WAS regardless of donor type. WAS-related complications are very rare events more than 6 months post HSCT. More patients required secondary procedures after treosulfan-based than busulfan-based conditioning. These data confirm the feasibility and efficacy of the regimens currently recommended by the IEWP. [Display omitted] DisclosuresSlatter:Medac: Other: Travel assistance. Chiesa:Gilead: Consultancy; Bluebird Bio: Consultancy. Kalwak:Sanofi: Other: travel grants; medac: Other: travel grants. Locatelli:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria. Sykora:Aventis-Behring: Research Funding; medac: Research Funding. Zecca:Chimerix: Honoraria. Veys:Pfizer: Honoraria; Servier: Research Funding; Novartis: Honoraria.

Efficacy and Toxicity of Donor Lymphocyte Infusions in the Management of Mixed Donor-Recipient Chimerism Following Allogeneic Stem Cell Transplantation for Lymphoid Malignancies:- a Study of the LWP-EBMT

Efficacy and Toxicity of Donor Lymphocyte Infusions in the Management of Mixed Donor-Recipient Chimerism Following Allogeneic Stem Cell Transplantation for Lymphoid Malignancies:- a Study of the LWP-EBMT

Reticular dysgenesis: international survey on clinical presentation, transplantation, and outcome

AbstractReticular dysgenesis (RD) is a rare congenital disorder defined clinically by the combination of severe combined immunodeficiency (SCID), agranulocytosis, and sensorineural deafness. Mutations in the gene encoding adenylate kinase 2 were identified to cause the disorder. Hematopoietic stem cell transplantation (HSCT) is the only option to cure this otherwise fatal disease. Retrospective data on clinical presentation, genetics, and outcome of HSCT were collected from centers in Europe, Asia, and North America for a total of 32 patients born between 1982 and 2011. Age at presentation was <4 weeks in 30 of 32 patients (94%). Grafts originated from mismatched family donors in 17 patients (55%), from matched family donors in 6 patients (19%), and from unrelated marrow or umbilical cord blood donors in 8 patients (26%). Thirteen patients received secondary or tertiary transplants. After transplantation, 21 of 31 patients were reported alive at a mean follow-up of 7.9 years (range: 0.6-23.6 years). All patients who died beyond 6 months after HSCT had persistent or recurrent agranulocytosis due to failure of donor myeloid engraftment. In the absence of conditioning, HSCT was ineffective to overcome agranulocytosis, and inclusion of myeloablative components in the conditioning regimens was required to achieve stable lymphomyeloid engraftment. In comparison with other SCID entities, considerable differences were noted regarding age at presentation, onset, and type of infectious complications, as well as the requirement of conditioning prior to HSCT. Although long-term survival is possible in the presence of mixed chimerism, high-level donor myeloid engraftment should be targeted to avoid posttransplant neutropenia.

Family Mismatched Donor Transplantation for Myelofibrosis: A Retrospective Analysis of the EBMT Chronic Leukaemia Working Party

Background: Allogeneic stem cell transplantation is a treatment option for patients with advanced myelofibrosis. Problems encountered include an increased risk of delayed or poor engraftment and in the mismatched unrelated donor setting a higher rate of GVHD and particularly poor outcomes. As for other indications for allogeneic stem cell transplants, patients for whom either a matched sibling or matched unrelated donor is not available are considered for either a double umbilical cord blood, a mismatched unrelated donor or haploidentical stem cell transplant. Data on the latter option are limited and we reviewed registry data on all family mismatched donor transplants performed between 2001 and 2015 and reported to the EBMT registry.Results: Records retrieved 69 patients with myelofibrosis transplanted between November 2001 and November 2015. 44 (64%) were male. 50 (74%) had primary myelofibrosis,18 (27%) had secondary myelofibrosis (6 from ET, 5 from PRV and 7 others) and unknown 1(2%). Of 25 patients for whom the JAK2 V617F mutation status was known, 15 (22%) harboured the mutation. Patient Karnofsky performance status was > 70% in 98%.Of the mismatched family donors, 47 (68%) were male and 22 (31%) female. Donors were HLA mismatched at 1 locus in 12 (17%) and 2 or more loci in 48 (69%). Donor-recipient serology combinations were CMV -/- in 8 (12%), +/- in 4 (6%), -/+ in 15 (22%) and +/+ in 34 (49%) missing 8 (12%).Bone marrow was the stem cell source in 34 (49%) and peripheral blood in 35 (51%). The median total nucleated cell count (TNC) infused was 7.5x108/kg (range 2.3-21x108/kg) from data available in 17 patients. The median CD34+ cell dose was 6.9x106/kg (range 1.9-18.18x106/kg) from data available in 19 patients.Conditioning was myeloablative in 48 (70%) and RIC in 21 (30%) The conditioning regimes were varied but the predominant ones were Fludarabine, Busulphan, ATG (FBATG) and Thiotepa, Busulphan, Fludarabine (TBF). TBI was administered in 8 (12%) and in vivo T cell depletion in 22 (32%), ex-vivo T cell depletion in 5 (7%) patients. GVHD prophylaxis varied with post transplant Cyclophosphamide administered in 34/67 (49%) and ATG in 19/67 patients (28%).Neutrophil engraftment was established in 53 (82%) at a median of 20 days (range 11-83). Primary graft failure occurred in 8 (12%) and secondary graft failure in 4 (6%). This occurred at a median of 12 months (range 4.5-35 months). Eleven of these patients had a second allograft at a mean interval of 6.4 months. Responses to the first allograft (censoring for patients who had a second allograft) with data available in 45 patients, showed that complete remission was achieved in 35 patients (78%), 6 (13%) were never in CR and 4 (9%) were not evaluable.The cumulative incidence of grade II-IV acute GvHD at 100 days was 12% (95% CI 4-21%) and for grade III-IV acute GvHD at 100 days it was 5% (95% CI 3-11%). Data for chronic GVHD was valid in 49 patients. The cumulative incidence of chronic GvHD at 2 years was 62% (95% CI 47-76%). The cumulative incidence of limited cGvHD was 45% (95% CI 31-59%) whereas the cumulative incidence of extensive cGvHD was 10% (95% CI 2-19%).The median follow up was 24 months (95% CI 13-35 months). The 2-year OS was 51% (95% CI 37-76%) and the 5-year OS was 38% (95% CI 21-55%). The 2-year RFS was 44% (95% CI 30-59%) and the 5-year RFS was 31% (95% CI 15-48%). The 2 year cumulative incidence of relapse was 14% (95% CI 5-24%). The 2 year NRM was 41% (95% CI 28-55%), which increased to 54% (95% CI 37-72%) at 5 years.The main causes of death were infection (16, 24%), GVHD (7, 10%) organ damage or failure (3, 5%), relapse/disease progression (1, 2%) and secondary malignancy or PTLD (1, 2%). On univariate analysis there was no significant effect of recipient gender, donor gender, degree of HLA mismatch 1 vs >1 Ag MM, CMV matching between donor and recipient, primary or secondary MF, disease stage at transplant (chronic versus advanced phase), conditioning intensity, conditioning regimen, GVHD prophylaxis with ATG or post transplant cyclophosphamide or stem cell source on overall survival.Conclusion: Concerns regarding engraftment and secondary graft failure have excluded patients with myelofibrosis from clinical trials of mismatched related donor transplant. The data suggest that engraftment is feasible, and PFS and OS can be attained with limited severe chronic GVHD with family mismatched donors in this setting. DisclosuresCiceri:MolMed SpA: Consultancy.

Mother Donors Improve Outcomes after HLA Haploidentical Hematopoietic Transplantation: A Retrospective Study By the Cell Therapy and Immunobiology Working Party of the EBMT

▪IntroductionTrans-placental trafficking of maternal and fetal cells during pregnancy establishes long-term, reciprocal micro-chimerism in both mother and child (Maloney et al., J Clin Invest, 104:41, 1999). As a consequence, the immune system of the mother may become sensitized to paternal histocompatibility antigens. In fact, antibodies directed against paternal HLA-antigens (van Rood JJ et al., Nature 181:1735, 1958) and T lymphocytes directed against paternal major and minor histocompatibility antigens (van Kampen CA et al., Hum Immunol 62:201, 2001; Verdijk RM et al., Blood 103:1961, 2004) were detected in multiparous women. More recently, it was hypothesized that mother's "exposure" to paternal HLA haplotype antigens during pregnancy may affect transplantation outcomes when the mother acts as donor for the child. Indeed, survival after T cell-depleted HLA haploidentical haematopoietic transplantation was improved using the mother as donor (vs all other family members) (Stern et al., Blood 112:2990, 2008; Kruchen et al., BMT 50:1367 2015). However, maternal donors were associated with increased incidence of GvHD and decreased survival after un-manipulated HLA haploidentical blood and marrow grafts (Wang Y et al., Blood 124:843, 2014).Patients and MethodsA retrospective EBMT registry-based study was performed in a combined series of adult (n=333) and pediatric (n=105) patients with acute leukemia (AML=268, ALL=160, Mixed phenotype=10) who received transplant from one MHC mismatched family donor. Forty-four percent (233) of patients were in I or II complete remission (CR) at the time of transplant, 193 were in chemo-resistant relapse or in CR > 2. Median age was 32.7 (range: 0.67-70). Seventy-one percent of patients received ex-vivo T cell depleted transplants. Twenty-two patients were given bone marrow and peripheral blood stem cells, the others were given peripheral blood cells only. The mother was used as donor in 98 patients.ResultsEighty patients developed acute GvHD ≥ grade II. At a median follow up of 58.7 months, 130 patients are alive without disease, 146 relapsed and 152 died of non-relapse mortality (NRM). Univariate analyses of factors influencing relapse-free survival (RFS) showed age, disease status at transplant, Karnofsky score and ex-vivo T cell depletion impacted significantly. As transplantation outcomes from family members other than mothers did not differ from one another, such transplants were combined for analyses. When compared with transplantation from all other family members (n=330), transplantation from mother donors (n=98) was associated with lower relapse incidence (RI) (28% vs 39%, P=0.06) and non-relapse mortality (NRM) (30% vs 40%, P=0.09) and, consequently, better relapse-free survival (RFS) (43% vs 21%, P < 0.001). Multivariate analyses showed transplantation from mother donors was an independent factor predicting better RFS (other donors vs mothers: HR: 1.42; CI: 1.01-2.00; P=0.04) and lower RI (other donors vs mothers: HR: 1.93; CI: 1.16-3.22; P = 0.01). In addition, transplantation in relapse (vs remission) predicted worse RFS (HR: 2.33, CI: 1.80-3.00, P < 0.001) such as ≥18 (vs < 18) adversely impacted on RFS (HR: 1.40, CI: 1.00-1.96, P=0.04).DiscussionOur retrospective analyses in 438 HLA haploidentical hematopoietic transplants for acute leukemia patients (pediatric and adult) show that transplantation from mother donors, when compared with transplantation from any other family member, is an independent factor predicting better outcomes, i.e., better RFS and lower RI. Mothers should therefore be preferred when selecting an HLA haploidentical family donor. Further clinical and preclinical studies are needed to unveil the mysteries underlying mother-to-child immune interaction during pregnancy and its bearing on the reproductive success of the human species. DisclosuresCiceri:MolMed SpA: Consultancy. Bonini:TxCell: Membership on an entity's Board of Directors or advisory committees; Molmed SpA: Consultancy.

Effect of stem cell source on long-term chimerism and event-free survival in children with primary immunodeficiency disorders after fludarabine and melphalan conditioning regimen

Reduced-intensity conditioning (RIC) regimens are increasingly being used in the transplantation of patients with primary immunodeficiency disorders (PIDs), but there are no large studies looking at long-term lineage-specific chimerism. We sought to analyze long-term chimerism and event-free survival in children undergoing transplantation for PIDs using RIC with fludarabine and melphalan (Flu/Melph) and to study the effect of donor type and stem cell source. One hundred forty-two children underwent transplantation with RIC by using Flu/Melph and for PIDs by using bone marrow (n=93) or peripheral blood stem cells (PBSCs; n=49). Donors were matched unrelated donors (n=72), mismatched unrelated donors (n=37), matched sibling donors (n=14), matched family donors (n=12), and mismatched family donors (n=7). Overall survival at a median follow-up of 7.5years was 78%, irrespective of stem cell source or donor type. When bone marrow was used as the stem cell source, 26% of patients ended up with very low levels of donor chimerism (<10% donor), especially in the myeloid lineage. Event-free survival in this group was significantly lower compared with that in the rest of the group (25% vs 70%, P<.001). With the use of PBSCs, more than 90% of patients achieved complete donor chimerism or high-level mixed chimerism (>50% donor chimerism) in all lineages. On the basis of our experience, we would suggest that PBSCs should be the stem cell source of choice in children with PIDs undergoing transplantation with Flu/Melph RIC from a matched donor source. This is most likely to ensure sustained high-level donor chimerism.

Effects of anti-NKG2A antibody administration on leukemia and normal hematopoietic cells.

Natural killer cells are key cells of the innate immune system. Natural killer cell receptor repertoires are diversified by a stochastic expression of killer-cell-immunoglobulin-like receptors and lectin-like receptors such as NKG2 receptors. All individuals harbor a subset of natural killer cells expressing NKG2A, the inhibitory checkpoint receptor for HLA-E. Most neoplastic and normal hematopoietic cells express HLA-E, the inhibitory ligand of NKG2A. A novel anti-human NKG2A antibody induced tumor cell death, suggesting that the antibody could be useful in the treatment of cancers expressing HLA-E. We found that immunodeficient mice, co-infused with human primary leukemia or Epstein-Barr virus cell lines and NKG2A(+) natural killer cells, pre-treated with anti-human NKG2A, were rescued from disease progression. Human NKG2A(+) natural killer cells reconstituted in immunodeficient mice after transplantation of human CD34(+) cells. These natural killer cells are able to kill engrafted human primary leukemia or Epstein-Barr virus cell lines by lysis after intraperitoneal administration of anti-human NKG2A. Thus, this anti-NKG2A may exploit the anti-leukemic action of the wave of NKG2A(+) natural killer cells recovering after hematopoietic stem cell transplants or adoptive therapy with natural killer cell infusions from matched or mismatched family donors after chemotherapy for acute leukemia, without the need to search for a natural killer cell alloreactive donor.