HLA-haploidentical Hematopoietic Stem Cell Transplantation Research Articles

Administration of BPX-501 Cells Following Αβ- T and B-Cell-Depleted HLA-Haploidentical HSCT in Children with Fanconi Anemia

Abstract Background Allogeneic hematopoietic stem cell transplantation (HSCT) has been shown to rescue trilineage cytopenias and to prevent occurrence of myeloid malignancies in patients with Fanconi Anemia (FA). HLA-identical family donor HSCT is a recommended treatment strategy with an ≥80% cure rate, and outcomes of HSCT from unrelated donors have progressively improved over time. However, HLA-partially matched (haplo) HSCTs have been historically associated with inferior results. Innovative approaches of graft manipulation, such as selective depletion of αβ-T and B cells, have recently been reported to improve the outcomes of haplo-HSCT in children with non-malignant disorders, however obstacles remain, such as delayed recovery of adaptive immunity with a risk of life-threatening infections. Novel strategies aimed at accelerating immune reconstitution are warranted to optimize the outcomes of patients transplanted from a HLA-haploidentical family donor. BPX-501 is an allogeneic product consisting of T cells modified to express the inducible caspase-9 (iC9) safety switch and truncated CD19 to allow monitoring and expansion of BPX-501 following transplant. The polyclonal nature of the BPX-501 provides broad virus and tumor-specific immunity, while the safety switch provides the unique ability to promptly and durably resolve graft-versus-host disease (GvHD) symptoms following the administration of rimiducid which induces dimerization and activation of iC9, inducing apoptosis of BPX-501. Aims To evaluate the safety and efficacy (acceleration of immune recovery and prevention of transplant-related mortality while maintaining low rates of acute and chronic GvHD) of BPX-501 administered after a αβ T and B-cell depleted haplo-HSCT in pediatric patients with FA. Methods This is a multicenter US (NCT03301168) and EU (NCT02065869), prospective trial utilizing αβ-T- and B-cell-depleted haplo-HSCT followed by infusion of donor lymphocytes genetically modified to express iC9 (BPX-501 T cells). BPX-501 cells were planned to be infused on day14±4 after the allograft per protocol. No post-transplant pharmacological GvHD prophylaxis was employed. Patients who develop GvHD resistant to conventional steroid therapy were eligible to receive ≥1 dose of dimerizing rimiducid activating iC9. The efficacy-evaluable population (EEP) was defined as any patient with FA who received HSCT, BPX-501 infusion and had at least one follow-up assessment. Results At the time of clinical cut-off (June 30th, 2018), 14 patients met the EEP definition. Nine and 5 patients were transplanted in the EU and US, respectively. The median follow-up was 23.5 mos (0.75 - 42 mos). Key baseline and transplant characteristics are detailed in Table 1. The median time for neutrophil and platelet engraftment was 14 (11-15) and 10 (8 - 11) days, respectively. One patient experienced primary graft failure (7.7% [95% CI: 0-22.2%]). Only one patient developed Grade I aGvHD (7.7% [95% CI: 0-22.2%]). Two patients developed cGvHD (19.2% [95% CI: 4-43.2%]), both cases being moderate. Rimiducid was not administered to any patient. One patient died after transplantation due to brain hemorrhage 25 days post HSCT. The event was unrelated to BPX-501 (TRM 7.1% [95% CI: 0-20.6%]). No patients died of infectious complications. The probability of both overall survival (OS) and disease-free survival (DFS) was 92.9% (95% CI: 79.4-100%). The median time from last red blood cell (RBC) transfusion was 23.6 mos (0.2 - 41.9 mos). CD3+ and CD3+CD4+ T cells above 500 cells/ml were achieved by 180 and 360 days, respectively. IgA and IgM levels achieved normal values by 30 and 180 days, respectively. The percentage of circulating and median absolute BPX-501 cells at Day 100 were 3.35% ± 2.94% (0 - 8.4%) and 29.09 ± 39.56 cells/ml (0 - 135 cells/ml), respectively. Conclusion These data indicate that the adoptive transfer of BPX-501 following αβ-T and B-cell depleted haplo-HSCT represents a novel and highly effective transplantation strategy for pediatric patients with FA. Further, despite the addition of BPX-501, low rates and severity of both acute and chronic GvHD was observed, a finding that could translate into significant long-term benefit, in terms of reduction of squamous cell carcinoma a well-known complication occurring in FA patients after HSCT. Disclosures Aldinger: Bellicum Pharmaceuticals, Inc.: Employment. Locatelli:Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Alpha/Beta T-Cell and B-Cell Depletion HLA-Haploidentical Hematopoietic Stem Cell Transplantation Is an Effective Treatment for Children/Young Adults with Acute Leukemia

Background: Allogeneic hematopoietic stem cell transplantation (HSCT) from an HLA-haploidentical relative (haplo-HSCT) is a suitable option for children/young adults with acute leukemia (AL) either relapsed or at high-risk of treatment failure and in urgent need of an allograft. A novel method of graft manipulation based on the selective, negative depletion of αβ T and B cells has been recently developed. We published the results of a prospective trial (ClinicalTrial.gov identifier: NCT01810120) enrolling 80 children with AL transplanted until September/2014 using this approach (Locatelli, Blood 2017). In the present analysis, we update those results, evaluating also additional patients given haplo-HSCT after that date.Patients and methods: Analyzed are 111 children with AL enrolled in the trial; median age is 10 years (range 0.9-22.2). Eighty-two (74%) and 29 (26%) patients had acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML), respectively; they were transplanted between 09/2011 and 05/2018. All children were transplanted in complete morphological remission and received a fully myeloablative preparative regimen. Details on patients' characteristics, as well as on the number of HSC and lymphocyte subsets infused, are shown in Table 1. The donor was mainly chosen according to immunological criteria, giving priority to NK-cell alloreactivity, evaluated according to the killer immunoglobulin-like receptor (KIR)/KIR-Ligand mismatch in graft-versus-host direction model, KIR B haplotype, higher B-content score and size of NK alloreactive subset. Anti-T lymphocyte globulin (ATLG Grafalon®, Neovii Biotech) was administered at a dose of 12 mg/Kg from day -5 to -3 for preventing graft rejection and graft-versus-host disease (GvHD). Moreover, to reduce the risk of EBV-related post-transplant lymphoproliferative disorder (PTLD), on day -1, patients received rituximab (200 mg/m2) for in vivo depletion of both donor and recipient B cells. No patient was given any post-transplantation pharmacological GvHD prophylaxis.Results: Median follow-up of surviving patients is 47 months (range: 2 months - 7.7 years). All patients but two successfully engrafted and the median time to neutrophil and platelet recovery was 13 (range 9-22) and 11 (range 8-20) days, respectively. Acute GvHD occurred in 28 patients; it was of grade I and grade II severity in 9 and 19 patients, respectively. Skin was the sole organ involved in all patients but one, who had gut involvement. The cumulative incidence of grade I-II acute GvHD was 25% (95% confidence interval, CI, 17-33). Four out of the 91 patients at risk developed chronic GvHD, in all cases of limited severity, the cumulative incidence of this complication being 5% (95% CI, 1-9). Six patients died for transplant-related complications, this resulting into a 5-year cumulative incidence of transplant-related mortality (TRM) of 6% (95% CI, 2-11). Twenty-three patients relapsed at a median time of 186 days (range 60-1012) after transplantation, the 5-year cumulative incidence of relapse being 24% (95% CI, 16-33). The 5-year probability of overall and leukemia free survival (LFS) were both above 70%, as shown in Figure 1A and 1B, respectively. The 5-year probability of LFS in children with ALL and AML was 69% (95% CI, 57-79) and 73% (95% CI, 52-86), respectively (Figure 1C). Use of total body irradiation (TBI) during the preparative regimen was associated with better patient's outcome (Figure 1D), since it protected against the risk of leukemia recurrence [18% (95% CI, 10-28) vs. 45% (95% CI, 22-66) in patients who did or did not receive TBI, respectively, p<0.01]. The correlation between use of TBI and better outcome remained significant in multivariable analysis, with a hazard ratio of 0.35 (95% CI, 0.16- 0.78, p=0.01) for LFS. The median CD3+ cell count on day +90, +180 and +360 were 247, 659 and 1380/mcl, respectively.Conclusions: This study, reporting long-term outcome of a large population of children/young adults with AL, confirms that αβ T- and B-cell depleted haplo-HSCT is an effective option for patients in need of an urgent allograft and lacking an HLA-identical donor. While TRM is impressively low, the main cause of treatment failure is leukemia recurrence, whose incidence can be lowered by the use of TBI during the conditioning regimen. The remarkably low risk of chronic GvHD renders the approach attractive also in terms of patient's quality of life. [Display omitted] DisclosuresLocatelli: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; bluebird bio: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria.

Thrombospondin-1, Platelet Factor 4, and Galectin-1 Are Associated with Engraftment in Patients with Sickle Cell Disease Who Underwent Haploidentical HSCT

BackgroundSickle cell disease (SCD) is an inherited red blood cell disorder which leads to significant morbidity and early mortality. The most widely available curative approach remains hematopoietic stem cell transplantation (HSCT). However, <15% SCD patients have human leukocyte antigen (HLA)- matched sibling donors. HLA-haploidentical (haplo) HSCT expands the donor pool considerably and is a practical alternative for these patients, but with an increased risk of allograft rejection. Biomarkers in patient plasma could potentially be helpful in predicting HSCT outcome and allow treatment at an early stage so that graft rejection could be reversed or prevented.ObjectiveThe purpose of the study was to detect variations in the plasma proteomes of engrafted patients as compared to those who rejected their grafts and elucidate mechanisms associated with engraftment.MethodsPatients were conditioned with alemtuzumab, 400cGy total body irradiation, and a dose escalation of post-transplant cyclophosphamide ranging from 0-100mg/kg (Fitzhugh CD et al. Blood Advances, 2017). Tandem Mass Tag (isobaric tags for relative quantification) was performed on plasma samples from engrafted (N=9) and rejected patients (N=10) who underwent haplo HSCT. Proteins with p-values <0.05, relative difference in protein concentration between groups >25%, and total number identified peptide sequences >2 were considered statistically significant. Bioinformatics tools (DAVID, GeneMANIA, STRING and LENS) were used to analyze the identified proteins. Biologically relevant proteins were further evaluated by ELISA to verify their association with the allograft status.ResultsThe proteomics analysis revealed 44 differentially expressed proteins between engrafted and rejected groups. Seven candidate proteins, namely thrombospondin-1 (TSP-1), platelet factor 4 (PF4), talin-1, moesin, cell division control protein 42 homolog, galectin-1 (GAL-1), and CD9 were selected for further analysis. Pathway enrichment analysis revealed that the differentially expressed proteins were mostly related to focal adhesion, rap1 signaling pathway, regulation of actin cytoskeleton platelet activation, and leukocyte transendothelial migration. The interaction network of the identified proteins indicated that the proteins were partially biologically connected.ELISA results of the 7 proteins revealed that TSP-1, PF4, and GAL-1 were significantly higher in the engrafted group as compared with the rejected group, African-American healthy volunteer group, and SCD group who had not been transplanted (see Figure 1). TSP-1 has been found to promote the survival of corneal transplants and is a major activator of transforming growth factor (TGF)-b signaling pathway (Saban DR et al. J Immunol, 2010), an important player in the initiation of immunological tolerance. PF4 has been observed to be associated with improved outcome in cardiac and kidney transplants (Shi G et al. J Clin Invest, 2014 and Zhang L et al. Inflammation, 2015), to enhance proliferation of regulatory T-cells, and to decrease Th17 differentiation (Shi G et al. J Clin Invest, 2014). Lastly, GAL-1 has been found to induce regulatory T- and regulatory B-cell function (Alhabbab R et al. Sci Rep, 2018).ConclusionsWe have shown for the first time that TSP-1, PF4,and GAL-1 are associated with engraftment in patients with SCD who undergo haplo HSCT. The study warrants further validation in a larger sample size as well as in vitro and in vivo analyses to evaluate whether our candidate proteins are associated with tolerance induction. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Human γδ T-Cells: From Surface Receptors to the Therapy of High-Risk Leukemias.

γδ T lymphocytes are potent effector cells, capable of efficiently killing tumor and leukemia cells. Their activation is mediated by γδ T-cell receptor (TCR) and by activating receptors shared with NK cells (e.g., NKG2D and DNAM-1). γδ T-cell triggering occurs upon interaction with specific ligands, including phosphoantigens (for Vγ9Vδ2 TCR), MICA-B and UL16 binding protein (for NKG2D), and PVR and Nectin-2 (for DNAM-1). They also respond to cytokines undergoing proliferation and release of cytokines/chemokines. Although at the genomic level γδ T-cells have the potential of an extraordinary TCR diversification, in tissues they display a restricted repertoire. Recent studies have identified various γδ TCR rearrangements following either hematopoietic stem cell transplantation (HSCT) or cytomegalovirus infection, accounting for their “adaptive” potential. In humans, peripheral blood γδ T-cells are primarily composed of Vγ9Vδ2 chains, while a minor proportion express Vδ1. They do not recognize antigens in the context of MHC molecules, thus bypassing tumor escape based on MHC class I downregulation. In view of their potent antileukemia activity and absence of any relevant graft-versus-host disease-inducing effect, γδ T-cells may play an important role in the successful clinical outcome of patients undergoing HLA-haploidentical HSCT depleted of TCR αβ T/CD19+ B lymphocytes to cure high-risk acute leukemias. In this setting, high numbers of both γδ T-cells (Vδ1 and Vδ2) and NK cells are infused together with CD34+ HSC and may contribute to rapid control of infections and leukemia relapse. Notably, zoledronic acid potentiates the cytolytic activity of γδ T-cells in vitro and its infusion in patients strongly promotes γδ T-cell differentiation and cytolytic activity; thus, treatment with this agent may contribute to further improve the patient clinical outcome after HLA-haploidentical HSCT depleted of TCR αβ T/CD19+ B lymphocytes.

Optimal donor for severe aplastic anemia patient requiring allogeneic hematopoietic stem cell transplantation: A large-sample study from China

HLA-haploidentical hematopoietic stem cell transplantation (HSCT) may be an option for severe aplastic anemia (SAA) patients. However, to date, no large-sample studies have been performed to determine which types of SAA patients are suitable for HLA-haploidentical HSCT. We retrospectively studied 189 consecutive patients with SAA who underwent HLA-identical or HLA-haploidentical HSCT at seven transplant centers in China. Propensity score matching (PSM) was applied in this study to reduce the influence of potential confounders. The 5-year overall survival (OS) rate was 72.0% in the HLA-haploidentical group and 76.5% in the HLA-identical group. The median time to achieve engraftment and the incidence of acute GVHD/chronic GVHD were not significantly different between the two groups. In the subgroup analysis, the outcome of patients older than 40 years in the HLA-haploidentical group was significantly poorer than that of patients younger than 40 years in the same group and that of patients older than 40 years in the HLA-identical group. Based on the above results, we suggest that HLA-haploidentical relative HSCT should be considered as a valid alternative option for patients younger than 40 years with SAA for whom no matched sibling donor is available.

Outcomes of Children with Hemophagocytic Lymphohistiocytosis Given Allogeneic Hematopoietic Stem Cell Transplantation in Italy

We report on 109 patients with hemophagocytic lymphohistiocytosis (HLH) undergoing 126 procedures of allogeneic hematopoietic stem cell transplantation (HSCT) between 2000 and 2014 in centers associated with the Italian Pediatric Hematology Oncology Association. Genetic diagnosis was FHL2 (32%), FHL3 (33%), or other defined disorders known to cause HLH (15%); in the remaining patients no genetic abnormality was found. Donor for first transplant was an HLA-matched sibling for 25 patients (23%), an unrelated donor for 73 (67%), and an HLA-partially matched family donor for 11 children (10%). Conditioning regimen was busulfan-based for 61 patients (56%), treosulfan-based for 21 (20%), and fludarabine-based for 26 children (24%). The 5-year probabilities of overall survival (OS) and event-free survival (EFS) were 71% and 60%, respectively. Twenty-six patients (24%) died due to transplant-related causes, whereas 14 (13%) and 10 (9%) patients experienced graft rejection and/or relapse, respectively. Twelve of 14 children given a second HSCT after graft failure/relapse are alive and disease-free. Use of HLA-partially matched family donors was associated with higher risk of graft failure and thus with lower EFS (but not with lower OS) in multivariable analysis. Active disease at transplantation did not significantly affect prognosis. These data confirm that HSCT can cure most HLH patients, active disease not precluding successful transplantation. Because in HLH patients HLA-haploidentical HSCT performed through CD34+ cell positive selection was found to be associated with poor sustained engraftment of donor cells, innovative approaches able to guarantee a more robust engraftment are warranted in patients given this type of allograft.

Влияние аллореактивности естественных киллерных клеток на эффективность аллогенной трансплантации гемопоэтических стволовых клеток с деплецией α/β TCR/CD19+ лимфоцитов у педиатрических пациентов с острыми лейкозами

Natural killer (NK) cells constitute the first lymphocyte population to recover after an allogeneic hematopoietic stem cell transplantation (HSCT). It is believed that NK cell alloreactivity is regulated by the difference between activating and inhibitory signals from activating and inhibitory killer cell immunoglobulin-like receptors (KIRs). Human Leukocyte Antigen (HLA) molecules serve as ligands for KIR receptors. NK cell alloreactivity is determined by a KIR-HLA mismatch between donor and patient as well as the presence of specific activating KIR genes. Numerous recent studies show that several factors influence the effectiveness of the graft-versus-leukemia reaction. In particular, these factors include donor’s KIR genotype and the transplant protocol. The aim of the study is to evaluate the influence of KIR genotype of both HLA-haploidentical related donors and HLA-identical unrelated donors on the relapse risk and survival of acute leukemia patients after allogeneic HSCT. The study includes 142 patients (the median age 11) with acute myeloid leukemia (n = 70) and acute lymphoid leukemia (ALL) (n = 72) received first HLA-identical unrelated (n = 64) and HLA-haploidentical (n = 78) with α/βTCR-depleted allogeneic HSCT. All patients were in complete hematologic remission at the moment of HSCT. Peripheral blood mononuclear cells were collected after the administration of granulocyte colony-stimulating factor and used as the source of hematopoietic stem cells. Results of the study are consistent with the conception that potential NK alloreactivity depends on the transplant protocol – conditioning regimen, transplant processing and post-transplant graft-versus-host-disease prophylaxis. The key finding of this study is that more number of activating KIR genes in donor’s KIR genotype is associated with better overall survival of ALL patients (0,67 (95% CI: 0,53–0,81) vs 0,31 (95% CI: 0,07–0,55); р = 0,016). A similar effect was observed for the event-free survival. We failed to find a beneficial effect of NK alloreactivity based on the «ligand-ligand» model in the HLA-haploidentical related HSCT. NK alloreactivity for the same patient group, based on receptor-ligand» model also showed no significant beneficial effect, however there was a tendency for better overall survival for patients transplanted from potentially NK alloreactive donors (0,76 (95% CI: 0,63–0,88) vs 0,56 (95% CI: 0,32–0,81); р = 0,486). In summary, it is recommended to consider donor’s KIR genotype as additional criteria for donor selection prior to allogeneic HSCT for all patients.

High-dose chemotherapy and autologous peripheral blood stem cell transplantation with BCVAC regimen followed by maintenance chemotherapy for children with very high risk acute lymphoblastic leukemia.

Allogeneic hematopoietic stem cell transplantation (HSCT) is the recommended treatment for children with very high risk acute lymphoblastic leukemia (ALL), but it requires adequate institutional infrastructure, experience, and expertise, especially for alternative donor HSCT. We review our experience with high-dose chemotherapy (HDCT) and autologous peripheral blood stem cell transplantation (APBSCT), followed by post-APBSCT maintenance chemotherapy for children with very high risk ALL.Between August 1997 and November 2012, our institute was not successful with HLA-haploidentical HSCT. Thus, if patients lacked HLA-matched allogeneic donors or cord blood donors, we treated them with HDCT and APBSCT with carmustine, etoposide, cytarabine, and cyclophosphamide, followed by post-APBSCT maintenance chemotherapy with vincristine, oral prednisolone, methotrexate, and 6-mercaptopurine.Ten patients underwent HDCT and APBSCT due to relapse, biphenotype leukemia, Philadelphia translocation, MLL rearrangement, hypodiploidy, and initial white blood cell count above 20.0×109/L. At a median 7.4years from HDCT to APBSCT, overall survival (OS) was 70.0%±14.5% and event-free survival (EFS) was 70.0%±14.5%. Adverse events were tolerable, without treatment-related mortality.This historical analysis may be a useful reference when allogeneic HSCT including alternative donor HSCT cannot be performed for children with very high risk ALL.

Outcome of children with acute leukemia given HLA-haploidentical HSCT after αβ T-cell and B-cell depletion

AbstractAllogeneic hematopoietic stem cell transplantation (HSCT) from an HLA-haploidentical relative (haplo-HSCT) is a suitable option for children with acute leukemia (AL) either relapsed or at high-risk of treatment failure. We developed a novel method of graft manipulation based on negative depletion of αβ T and B cells and conducted a prospective trial evaluating the outcome of children with AL transplanted with this approach. Eighty AL children, transplanted between September 2011 and September 2014, were enrolled in the trial. All children were given a fully myeloablative preparative regimen. Anti–T-lymphocyte globulin from day −5 to −3 was used for preventing graft rejection and graft-versus-host disease (GVHD); no patient received any posttransplantation GVHD prophylaxis. Two children experienced primary graft failure. The cumulative incidence of skin-only, grade 1-2 acute GVHD was 30%; no patient developed extensive chronic GVHD. Four patients died, the cumulative incidence of nonrelapse mortality being 5%, whereas 19 relapsed, resulting in a 24% cumulative incidence of relapse. With a median follow-up of 46 months for surviving patients, the 5-year probability of chronic GVHD-free, relapse-free survival (GRFS) is 71%. Total body irradiation–containing preparative regimen was the only variable favorably influencing relapse incidence and GRFS. The outcomes of these 80 patients are comparable to those of 41 and 51 children given transplantation from an HLA-identical sibling or a 10/10 allelic-matched unrelated donor in the same period. These data indicate that haplo-HSCT after αβ T- and B-cell depletion represents a competitive alternative for children with AL in need of urgent allograft. This trial was registered at www.clinicaltrials.gov as #NCT01810120.

Sirolimus in treatment of acute graft-versus-host disease after HLA-haploidentical hematopoietic stem cell transplantation: report of one case and review of literature

目的 观察西罗莫司治疗单倍体造血干细胞移植后激素难治性急性移植物抗宿主病（aGVHD）疗效及并发症。 方法 报道1例男性21岁高白细胞型急性淋巴细胞白血病患者临床资料，并进行国内外相关文献复习。该患者造血干细胞移植后皮肤aGVHD经激素及FK506治疗无效，换西罗莫司治疗。 结果 患者移植后+63天出现皮肤aGVHD（Ⅱ度），给予甲泼尼龙治疗后加重，+74天合并血小板减少，将环孢素换为他克莫司，症状未缓解，并继发糖尿病、高血钾、房颤等，+100天将他克莫司替换为西罗莫司，皮疹消失、血钾及血糖恢复正常。+130天血象示三系重度减低，停用西罗莫司9 d后血象恢复正常并出院随访至截稿日。 结论 西罗莫司治疗造血干细胞移植后aGVHD有效，其与伏立康唑合用时需减量90%，即使密切监测血药浓度，仍须警惕其致重度骨髓抑制的可能。

Low incidence of acute graft-versus-host disease with short-term tacrolimus in haploidentical hematopoietic stem cell transplantation

Although tacrolimus (Tac) has immunosuppressive properties and exhibits promising efficacy against graft-versus-host disease (GVHD), little is known about Tac in the prophylaxis of GVHD after HLA-haploidentical hematopoietic stem cell transplantation (haplo-HSCT). In a multicenter randomized controlled trial, 174 patients received haplo-HSCT with GVHD prophylaxis involving short-term Tac (from −8days to +30days) or cyclosporine (CsA). The 100day cumulative incidences of acute GVHD (aGVHD) and grade III–IV aGVHD with the short-term Tac regimen and CsA regimen were 29.1 (19.5–38.7)% vs. 50.0(39.6–60.4)% (p=0.005) and 3.6(0.0–7.5)% vs. 13.5(6.1–20.9)% (p=0.027), respectively. There were no significant differences in the incidences of chronic GVHD (cGVHD), relapse and cytomegalovirus infection. Lymphocyte subset analysis showed that T cells decreased to lower levels on the short-term Tac regimen within 3 months of transplantation. The disease-free survival and overall survival on the short-term Tac and CsA regimens were 59.3 (48.9–69.7)% vs. 55.7 (45.3–66.1)% (p=0.696) and 65.1 (55.1–75.1)% vs. 61.4 (51.2–71.6)% (p=0.075), respectively. Our findings indicate that the short-term Tac regimen for GVHD prophylaxis in patients undergoing haplo-HSCT is associated with a low incidence and slight severity of aGVHD and did not increase the incidence of relapse and cytomegalovirus infection.

136 - LONG TERM Outcomes of Pediatric Patients with Malignant and NON-Malignant Disorders Receiving Α/Β T-CELL Depleted HLA-Haploidentical Hematopoietic STEM CELL Transplantation (HSCT) Followed by Infusion of BPX-501 T CELLS (DONOR T CELLS Transduced with IC9

136 - LONG TERM Outcomes of Pediatric Patients with Malignant and NON-Malignant Disorders Receiving Α/Β T-CELL Depleted HLA-Haploidentical Hematopoietic STEM CELL Transplantation (HSCT) Followed by Infusion of BPX-501 T CELLS (DONOR T CELLS Transduced with IC9

Alternative Donor Transplantation Using Intensified Conditioning, T-Cell-Replete HLA-Haploidentical Grafts and Post-Transplantation Cyclophosphamide in the Treatment of High-Risk and Advanced ALL: Feasibility and Outcome

Unmanipulated, T-cell-replete (TCR) HLA-haploidentical hematopoietic stem cell transplantation (haplo-HSCT) using post-transplantation cyclophosphamide (PTCY) for selective in vivo T-cell depletion of allo-reactive T-cells has become a valuable treatment alternative in patients with various hematologic disorders who lack a conventional donor or need timely transplant due to aggressive disease. However, as of yet few data are available for the treatment of ALL with this approach, particularly in relapsed and refractory disease.To evaluate the outcome of TCR haplo-HSCT utilizing PTCY in the context of intensified conditioning in patients with high-risk, relapsed and refractory ALL, we retrospectively analysed 29 patients (B-ALL n=27, T-ALL n=2; 12 male; median age 42 years: range 8-68) transplanted between 2010 and 2015 in five German transplant centers including one pediatric. Disease was active (relapsed/refractory) in 14 patients (48%) while others were in first (35%) or subsequent remission (17%). Eleven patients (38%) had relapsed after a previous allogeneic transplantation. Patients not in CR received cytoreductive chemotherapy prior to the conditioning regimen, according to the "sequential therapy" concept (Schmid C et al., JCO 2005; Tischer J et al, Ann Hematol 2013). Conditioning was TBI-based in 15 adults consisting of fludarabine and +/- cyclophosphamide plus either 12 Gy TBI or 8 Gy TBI applied in patients older than 55 years; children (n=3) received 10-12 Gy TBI plus etoposide. In adults with relapse after a first allogeneic transplantation conditioning was drug-based replacing TBI with treosulfan (3 x 10-12 g/m2) and etoposide. Post-grafting immunosuppression was high-dose cyclophosphamide, tacrolimus or cyclosporine A (n=4) and MMF in all patients. 27/29 patients engrafted, while 2 patients died early in aplasia. No primary graft rejection was observed. Acute GvHD grade II-IV occurred in 7 patients (24%); no patient developed grade IV acute GvHD. Mostly mild to moderate chronic GvHD was observed in 6 patients (21%), and CI of chronic GvHD at 2 years was 25%. No patient died due to GvHD. Severe toxicity (grade III-IV) was observed in 12 patients (41%), most commonly mucositis (n=34%), diarrhoea (31%), hyperbilirubinemia and transient elevation of transaminases (28%) and hemorrhagic cystitis (21%). CMV reactivated in 11/23 patients at risk and EBV in 3 while no patient developed CMV disease or PTLD. Proven invasive aspergillosis was diagnosed in 2, probable invasive aspergillosis in 5 patients. One-year non-relapse mortality (NRM) was 10%. Patients grafted with active disease experienced a one-year NRM of 14%. One-year relapse incidence was 35%. After a median follow up of 31 months (range 7.1-53.6), estimated one-year and three-year overall and relapse-free survival was 72/49% and 55/41%, respectively.In summary, intensification of the preparative regimen is well tolerated in the setting of TCR haplo-HSCT using PTCY as GvHD prophylaxis with low GVHD rates and NRM in patients with high-risk, relapsed and refractory ALL, while providing effective anti-leukemic activity. Results are at least comparable to HLA-matched transplantation. Thus, we suggest that the donor pool can be safely expanded in patients with high-risk and advanced ALL who lack a conventional donor, and that unrelated donor transplantation might be challenged in patients suffering from aggressive disease in the future. DisclosuresAlbert:GSK: Research Funding.

T-cell-rich HLA-haploidentical hematopoietic stem cell transplantation for relapsed/refractory pediatric Philadelphia chromosome-positive acute lymphoblastic leukemia without posttransplant tyrosine kinase inhibitor therapy.

Intensive chemotherapy with tyrosine kinase inhibitor (TKI) improves the prognosis of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph-ALL). However, the prognosis of cases of relapsed or refractory Ph-ALL remains poor. Here, we aimed to assess the efficacy of T-cell-rich HLA-haploidentical hematopoietic stem cell transplantation (TCR-haplo-HSCT) in eight patients with relapsed or refractory pediatric Ph-ALL. Transplant-related mortality was observed in two patients. All patients discontinued TKI after receiving TCR-haplo-HSCT. The 3-year probability of overall survival and event-free survival was 75.0 and 62.5%, respectively. These results indicate the efficacy of TCR-haplo-HSCT for relapsed/refractory pediatric Ph-ALL.

Human Herpesvirus 6 replication predicts Cytomegalovirus reactivation after allogeneic stem cell transplantation from haploidentical donor

Background and objectivesSince HHV-6 reactivation after transplant has been reported to increase the risk of CMV infection, we tested this hypothesis in the HLA-haploidentical hematopoietic stem cell transplantation setting. Study designFrom February 2011 to October 2015, 75 patients received hematopoietic stem cell transplantation using a T-cell replete graft from a HLA-haploidentical donor at our Institution. ResultsInterestingly, 87% of HHV-6 reactivations were followed by a CMV reactivation, at a median of 15days between the two viruses. Incidence of CMV reactivation was 14.5-fold higher in those patients with prior HHV-6 reactivation vs. those without it (p-value<0.001). ConclusionThe present results suggest that HHV-6 can be considered as a predicting indicator of cellular immunosuppression preceding the onset of CMV infection.

Selective Depletion of αβ T Cells and B Cells for Human Leukocyte Antigen–Haploidentical Hematopoietic Stem Cell Transplantation. A Three-Year Follow-Up of Procedure Efficiency

HLA-haploidentical family donors represent a valuable option for children requiring allogeneic hematopoietic stem cell transplantation (HSCT). Because graft-versus-host diseases (GVHD) is a major complication of HLA-haploidentical HSCT because of alloreactive T cells in the graft, different methods have been used for ex vivo T cell depletion. Removal of donor αβ T cells, the subset responsible for GVHD, and of B cells, responsible for post-transplantation lymphoproliferative disorders, have been recently developed for HLA-haploidentical HSCT. This manipulation preserves, in addition to CD34+ progenitors, natural killer, γδ T, and monocytes/dendritic cells, contributing to anti-leukemia activity and protection against infections. We analyzed depletion efficiency and cell yield in 200 procedures performed in the last 3 years at our center. Donors underwent CD34+ hematopoietic stem cell (HSC) peripheral blood mobilization with granulocyte colony–stimulating factor (G-CSF). Poor CD34+ cell mobilizers (48 of 189, 25%) received plerixafor in addition to G-CSF. Aphereses containing a median of 52.5 × 109 nucleated cells and 494 × 106 CD34+ HSC were manipulated using the CliniMACS device. In comparison to the initial product, αβ T cell depletion produced a median 4.1-log reduction (range, 3.1 to 5.5) and B cell depletion led to a median 3.4-log reduction (range, 2.0 to 4.7). Graft products contained a median of 18.5 × 106 CD34+ HSC/kg recipient body weight, with median values of residual αβ T cells and B cells of 29 × 103/kg and 33 × 103/kg, respectively. Depletion efficiency monitored at 6-month intervals demonstrated steady performance, while improved recovery of CD34+ cells was observed after the first year (P = .0005). These data indicate that αβ T cell and B cell depletion of HSC grafts from HLA-haploidentical donors was efficient and reproducible.

Phase II Multicenter, Randomized, Double-Blind Controlled Study of Efficacy and Safety of Umbilical Cord–Derived Mesenchymal Stromal Cells in the Prophylaxis of Chronic Graft-Versus-Host Disease After HLA-Haploidentical Stem-Cell Transplantation

Although mesenchymal stromal cells (MSCs) possess immunomodulatory properties and exhibit promising efficacy against chronic graft-versus-host disease (cGVHD), little is known about the efficacy of MSCs in the prophylaxis of cGVHD after HLA-haploidentical hematopoietic stem-cell transplantation (HLA-haplo HSCT). In this multicenter, double-blind, randomized controlled trial, we investigated the incidence and severity of cGVHD among patients, and the changes in T, B, and natural killer (NK) cells after the repeated infusion of MSCs. The 2-year cumulative incidence of cGVHD in the MSCs group was 27.4% (95% CI, 16.2% to 38.6%), compared with 49.0% (95% CI, 36.5% to 61.5%) in the non-MSCs control group (P = .021). Seven patients in the non-MSCs control group had severe lung cGVHD, but no patients in the MSCs group developed typical lung cGVHD (P = .047). After the MSC infusions, increasing memory B lymphocytes and regulatory T cells, as well as the ratio of type 1 T helper to type 2 T helper cells, were observed, whereas the number of NK cells decreased. Our findings suggest that the repeated infusion of MSCs might inhibit cGVHD symptoms in patients after HLA-haplo HSCT, accompanied by changes in the numbers and subtypes of T, B, and NK cells, leading to the acquisition of immune tolerance.

HLA-haploidentical hematopoietic stem cell transplantation: current status and future perspectives

HLA-haploidentical hematopoietic stem cell transplantation from related donors has gained attention as an alternative treatment for patients who do not have HLA-identical siblings and lack the time to search for HLA-matched unrelated donors due to availability for nearly all individuals. As a key factor in the success of this approach is depletion of donor T cells, HLA-haploidentical transplantation has rapidly gained acceptance worldwide with the development of three platforms: 1) CD34-positive cell selection using CliniMACS®; 2) the conditioning regimen with anti-thymocyte globulin; and 3) a recently-developed, post-transplant cyclophosphamide regimen. Since the high efficacy of T-cell-depletion provides both sufficient suppression of GVHD and a high risk of opportunistic infection, there is an urgent need to strengthen the prevention of viral infections. On the other hand, conditioning with ATG and the post-transplant cyclophosphamide regimen are becoming the strategies mainly used in haploidentical transplantation because of high practicability and low risk of infection, though these platforms necessitate other drugs for GVHD prophylaxis due to the low efficacy of T cell depletion. Together with progress in these platforms, outcomes of haploidentical transplantation are comparable to outcomes of HLA-matched transplants. Currently, HLA-haploidentical transplantation is increasingly being recognized as a novel breakthrough in hematopoietic stem cell transplantation.

Clinical Outcome and Immune Recovery after Adoptive Infusion of BPX-501 Cells (donor iC9-transduced T cells) in Children with Wiskott-Aldrich Syndrome (WAS) Given Alfa/Beta T-Cell Depleted HLA-Haploidentical Hematopoietic Stem Cell Transplantation (HSCT)

Clinical Outcome and Immune Recovery after Adoptive Infusion of BPX-501 Cells (donor iC9-transduced T cells) in Children with Wiskott-Aldrich Syndrome (WAS) Given Alfa/Beta T-Cell Depleted HLA-Haploidentical Hematopoietic Stem Cell Transplantation (HSCT)

GVHD Prophylaxis with Short Course MTX and Tacrolimus in HLA-Haploidentical Hematopoietic Stem Cell Transplantation Using Post-Transplant High Dose Cyclophosphamide

GVHD Prophylaxis with Short Course MTX and Tacrolimus in HLA-Haploidentical Hematopoietic Stem Cell Transplantation Using Post-Transplant High Dose Cyclophosphamide