Haploidentical Stem Cell Grafts Research Articles

Haploidentical Cord Blood Transplantation with 8 mg/kg Antithymocyte Globulin as Graft-versus-Host Disease Prophylaxis Compared to Haploidentical Transplantation with 10 mg/kg Antithymocyte Globulin in the Treatment of Acute Leukemia

Clinical outcomes of the transplantation strategy combined with a haploidentical stem cell graft and an unrelated umbilical cord blood unit (haplo-cord HSCT) with low-dose antithymocyte globulin (ATG) as graft-versus-host disease (GVHD) prophylaxis for the treatment of acute leukemia remains unclear. This study aimed to explore the clinical outcomes of haplo-cord HSCT in acute leukemia patients with the GVHD prevention strategy of 8 mg/kg ATG compared with haploidentical transplantation with 10 mg/kg ATG. A total of 130 patients with acute leukemia who underwent allogeneic HSCT between January 2016 and December 2020 were included in this study, including 70 patients who received haploidentical stem cell grafts and unrelated umbilical cord blood units (haplo-cord HSCT) with 8 mg/kg ATG (haplo-cord-ATG8 group) and haploidentical HSCT with 10 mg/kg ATG (haplo-ATG10 group) in 60 patients. Clinical data were collected and analyzed retrospectively. Patients in the haplo-cord-ATG8 group were significantly older compared with the haplo-ATG10 group (P=.000). Haplo-cord HSCT with reduced ATG to 8 mg/kg results in more rapid neutrophil recovery (P=.036). No between-group differences were observed in platelet recovery or the incidences of Epstein-Barr virus viremia, bloodstream infection, or hemorrhagic cystitis. The rate of grade II-IV acute GVHD by day 100 post-transplantation was higher in the haplo-ATG10 group (27.16% versus 11.48%; P=.033), as was the rate of chronic GVHD at 1 year (14.60% versus 3.36%; P=.048). The rate of cytomegalovirus reaction was higher in the haplo-ATG10 group (48.31% versus 26.30%; P=.022). With a median follow-up of 27.4 months for the haplo-cord-ATG8 group and 27.5 months for the haplo-ATG10 group, overall survival (OS) at 2 years was 79.4% versus 62.8% (P=.005), event-free survival (EFS) was 76.3% versus 55.9% (P=.001), the cumulative incidence of relapse was 10.11% versus 25.97% (P=.164), and nonrelapse mortality (NRM) was 14.33% versus 24.43% (P=.0040). Multivariate analysis identified Center for International Blood and Marrow Transplant Research Disease Risk Index was the sole significant predictor of relapse, NRM, OS, and EFS. Haplo-cord HSCT supported by cord blood with 8 mg/kg ATG as GVHD prophylaxis results in better outcomes compared with haplo-HSCT with 10 mg/kg ATG.

The Two-Step Allogeneic Stem Cell Transplantation Approach Results in Rapid Engraftment and Excellent Outcomes in Patients with Lymphoid Malignancies

The 2-step graft engineering approach has been the main platform for allogeneic hematopoietic cell transplantation (allo-HCT) at Thomas Jefferson University since 2005. We have previously described separating donor lymphocyte infusion followed by cyclophosphamide for bidirectional tolerization from CD34-selected hematopoietic grafts in haploidentical and matched related donors. Here we analyzed 60 patients with high-risk lymphoid malignancies who underwent a 2-step allo-HCT between 2008 and 2020. The majority of patients received haploidentical stem cell grafts (82%), and 20% of patients received matched related donor stem cell grafts. The patients underwent allo-HCT for diffuse large C cell lymphoma (n=17; 28%), chronic lymphoblastic leukemia (n=10; 17%), follicular lymphoma (n=8; 13%), and Hodgkin lymphoma (n=7; 12%). Eight patients (13%) had received prior high-dose chemotherapy. Thirty patients (50%) had a Hematopoietic Cell Transplantation Comorbidity Index ≥3, and 20 patients (33%) had a Center for International Blood & Marrow Transplant Research Revised Disease Risk Index of high risk or very high risk. The median patient age was 56 years (range, 24 to 75 years). Neutrophils engrafted at a median of 11 days (range, 9 to 16 days), and platelets engrafted at a median of 16 days (range, 13 to 37 days). With a median follow-up of 6 years, the 3-year probability of overall survival was 62.9% (95% confidence interval [CI], 49.3% to 73.8%), and that of disease-free survival was 60.2% (95% CI, 46.4% to 71.6%). The cumulative incidence of relapse at 3 years was 11.9% (95% CI, 5.2% to 21.6%). The cumulative incidence of nonrelapse mortality at 3 years was 30.1% (95% CI, 1.91% to 42.0%). The cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) at 1 year was 45% (95% CI, 32.2% to 57.0%), and that of grade III-IV acute GVHD at 1 year was 5% (95% CI, 1.3% to 12.6%). The cumulative incidence of cGVHD at 3 years was 15.2% (95% CI, 7.5% to 25.4%). The 2-step approach achieved excellent outcomes in high-risk lymphoid malignancies, with rapid neutrophil and platelet recovery.

Clinical Outcomes of B Cell Acute Lymphoblastic Leukemia Patients Treated with Haploidentical Stem Cells Combined with Umbilical Cord Blood Transplantation

Clinical outcomes of hematopoietic stem cell transplantation (HSCT) using a haploidentical stem cell graft and an unrelated umbilical cord blood unit (haplo-cord HSCT) for the treatment of B cell acute lymphoblastic leukemia (B-ALL) remain unclear. This study was conducted to explore the clinical outcomes of haplo-cord HSCT in patients with B-ALL. A total of 112 B-ALL patients who underwent haplo-cord HSCT and 64 B-ALL patients who underwent haploidentical HSCT (haplo-HSCT) at our center between 2010 and 2020 were retrospectively included in this study, and clinical outcomes and prognostic factors were further analyzed. Of the 112 haplo-cord HSCT recipients, 106 (94.6%) achieved complete haploidentical chimerism and 6 (5.4%) had mixed cord blood chimerism. No differences in neutrophil and platelet recovery or in the incidences of graft-versus-host disease, cytomegalovirus/Epstein-Barr virus viremia, bloodstream infection, or hemorrhagic cystitis were observed between the haplo-cord HSCT and haplo-HSCT groups. Compared with the haplo-HSCT group, the haplo-cord HSCT group had a higher absolute number of CD3+ cells (P=.029) and a lower ratio of CD3+CD4+ /CD3+CD8+ cells (P=.049) at 1 month post-transplantation. Moreover, the haplo-cord HSCT group had lower minimal residual disease (MRD) levels at 1 month (P=.020) and 100 days (P=.038) post-transplantation and a better 3-year prognosis (overall survival, P=.016; disease-free survival, P=.041; cumulative incidence of relapse [CIR], P=.016). The CIRs in patients with adverse genomic features (P=.040) or flow cytometry-based MRD (FCM-MRD) ≥1×10-4 (P=.033) were improved by haplo-cord HSCT. Multivariate analysis revealed that haplo-cord HSCT could independently improve the 3-year OS, DFS, and CIR of B-ALL patients (OS, P=.029; DFS, P=.024; CIR, P=.024). In addition, allo-HSCT at first complete remission was an independent parameter associated with 3-year OS for B-ALL patients (P=.014). An FCM-MRD ≥1×10-4 pre-HSCT could independently predict unfavorable 3-year DFS and CIR (DFS, P=.020; CIR, P=.036) in B-ALL patients. Our data suggest that the use of haplo-cord HSCT can independently improve survival in patients with B-ALL.

Rapid and Safe T Cell Immune Reconstitution By T Cell Progenitor Injection Following Haploidentical Transplantation for Severe Combined Immunodeficiency (SCID)

Severe Combined Immunodeficiencies (SCID) are defined by a complete absence of T lymphocytes in the blood and lymphoid organs, with variable defects in other WBC subsets depending on the gene defect. From a clinical perspective SCIDs are characterized by early development of life-threatening infections accounting for early death if untreated. The treatment of choice is allogeneic HSCT with very high success rates if a HLA identical sibling (MRD) or unrelated donor (MUD) is used. However, due to the scarcity of matched-related donors, SCID can benefit from haploidentical HSCT. In contrast to the continuous improvement of HLA compatible donor transplantations, no significant improvements have been obtained over the last twenty years for haploidentical HSCT. The profound immunodeficiency during the first months following haploidentical HSCT exposes patients to opportunistic viral, bacterial and fungal infections, which account for approximately 30-40% of the transplant related mortality (TRM). The rapid restoration of the T-cell compartment is the main aim of stem cell therapy in this setting. To this end we have recently set up a phase I/II clinical trial (ClinicalTrials.gov Identifier: NCT03879876) aiming to accelerate the immune reconstitution by injection of ex vivo generated Human T lymphoid progenitors (ProTcell TM) following haploidentical HSCT. T cell progenitors in this trial are generated in vitro within 7 days from mobilized peripheral blood (mPB) CD34 + hematopoietic stem and precursor cells (HSPCs) using our Notch ligand Delta-like 4 GMP culture platform so called SMART Immune's SMART101 product.This open-label, non-randomized study evaluates safety and efficacy of the SMART101 injection following CD34 + selected, haploidentical HSCT in SCID patients and is designed as a dose-escalation study comprising 6 doses of the SMART101 product obtained from the patient's haploidentical stem cell graft. The aim of this protocol is to define the highest efficacy dose without any toxicity.The conditioning regimen is based on Busulfan and Fludarabine according to IE-WP/EBMT guidelines with upfront administration of ATG to prevent graft rejection. Tight monitoring of ATG serum levels is applied in order to assure injection of SMART101 when ATG is below the lymphotoxicity threshold.Here we report the results of the first two SCID patients. P1 presented a homozygous Artemis deficiency. At diagnosis he had an ALC of 341/µl, with complete absence of T cells (CD3 + < 4/µl, CD4 + < 1/µl, CD8 + < 2/µl) and B cells (CD19 + 0/µl). NK cells were present in the normal range for age (CD16 +CD56 + 331/µl).In the absence of an HLA compatible donor, the patient's father was chosen as haploidentical stem cell donor.P1 received upfront ATG (5 mg /kg total dose), Busulfan (AUC of 16058 microM.min) and Fludarabine (160 mg/m²). He received Defibrotide prophylaxis from D0 until D+21, as well as Ursodeoxycholic acid until D+80. The CD34 + immunoselected graft contained 1.04 x 10 8 nucleated cells/kg with 24.15 x10 6 CD34 + cells/kg and 4000 CD3 + cells/kg on D0. After ATG monitoring 0.12x10 6 Smart101 cells were administered at D+14 post- HSCT.In the follow-up P1 didn't develop any acute or chronic SAEs, no acute or chronic GVHD, and no infection. He was discharged at D+121 post HSCT.The day +100 post transplantation CD4 + cell count/microliter exceeded 10 times the CD4 + count of our historical cohort of RAG1/2 or Artemis deficient patients transplanted with haploidentical HSCT alone following the same conditioning regimen.At 6 months post HSCT this difference remains important (851 versus 300 CD4 + cells/µl); Ig replacement therapy could be stopped as early as 9 months post transplantation and vaccinations have been started. At last follow up; almost 14 months post HSCT P1 is alive and well.P2 had an undefined molecular SCID diagnosis. She has been treated with the same conditioning regimen and received the second dose of 0.2x10 6 CD7 + cells, but unfortunately died from severe VOD emphasizing the need to replace chemotherapy with less toxic myeloablative agents.The preliminary results obtained after injection of Human T lymphoid progenitors in P1 are encouraging. While deserving confirmation in larger numbers of patients they could represent an important step forward in improving the outcome of haploidentical HSCT for SCID. DisclosuresCavazzana: Smart Immune: Other: co-founder.

Naive T-cell depletion in stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (HCT) is curative in many patients with advanced hematopoietic malignancies. Donor T cells not only facilitate engraftment and protect against opportunistic pathogens and residual disease, but can also cause graft-versus-host disease (GVHD), with significant morbidity and mortality. Complete T-cell depletion can not only substantially reduce GVHD rates but can also delay immune reconstitution and increase rates of opportunistic infections and relapse. Murine models have shown that naive T cells (TNs) consistently cause severe GVHD, whereas memory T cells cause milder or no GVHD and have critical graft-versus-tumor function. Informed by experiments performed in murine models of HCT, clinical trials are being conducted to evaluate TN-depleted peripheral blood stem cell (PBSC) grafts. These trials are showing very low rates of chronic GVHD and of serious acute GVHD in the HLA-matched HCT setting, with lower frequencies of opportunistic infections than after fully T-cell-depleted HCT and no apparent increase in relapse rates. Randomized clinical trials are ongoing, comparing standard unselected HCT with TN-depleted PBSCs and other promising GVHD-reduction strategies. Correlative laboratory studies will clarify how antitumor function is retained in TN-depleted HCT and inform strategies to further augment graft-versus-leukemia in patients at a high risk of relapse. TN depletion of donor lymphocyte infusions and of haploidentical stem cell grafts is also being investigated.

Complementary Transplantation with Haploidentical Stem Cells and Unrelated Cord Blood for Leukemia and Thalassemia

BackgroundUnrelated Cord Blood (UCB) Transplantation is a potentially curative therapy for leukemia and thalassemia; however, engraftment failure and slow immune reconstitution remain key clinical issues. We hypothesized that complementary transplantation (CT) of UCB with haploidentical stem cell graft (hap-SC) tolerized with post-transplant cyclophosphamide would result in rapid engraftment and low relapse rate without additional risk of graft-versus-host disease (GVHD). Therefore, we developed a novel complementary transplant approach.Patients and MethodSixty-six patients received CT between December 2012 and June 2016. Of them, 30 patients had malignance diseases (MD), including 11 lymphoid and 19 myeloid diseases, and 36 had thalassemia major (TM). Median age was 12 (range; 2-13) and 8 (3-17) years in the MD and TM group, respectively. Median follow-up time was 13 (7-32) and 19 (2-25) months, respectively. Conditioning (Regimen CT-13) included Cyclophosphamide on day-8 to -7, Busulfan on day-6 to -4, Fludarabine on day-6 to -2 and Thiotepa on day-3. Hap-SC was infused on day 0. GVHD prophylaxis consisted of Cyclophosphamide on day+3 to +4. UCB was infused on Day+6. Mycophenolate mofetil and Tacrolimuswas started on day+6 for GVHD prophylaxis. For 26 TM patients transplanted since 2014, they received identical regimen except with the additional Thymoglobulin on day -11 to -9 (Regimen CT-14).ResultsThe chimerism status at last follow-up was Hap-SC, UCB, mixed stem cells (MSC) and rejection in 20, 9, 1 and 0 patient in the MD group; and 16, 14, 3 and 3 patients in the TM group. Interesting, the initial chimerism on day+28 in the TM group was Hap-SC, UCB and MSC engrafted in 15, 7 and 12 patients, respectively. Thus, the MSC was not stable in TM patients; UCB typically became dominant overtime instead of the initial majority from hap-SC (Fig. 1).In the MD group, the time to neutrophil >= 0.5x109/L, platelet >=20 x109/L and hemoglobin >=80 g/L was day+18 (14-36), +10.0 (6-51) and +7 (1-20) in the final hap-SC engrafted group; and+30 (22-35), +25 (1-64) and +7 (3-28) in the final UCB engrafted group. Overall survive (OS), disease-free survive (DFS), relapse incidence (RI) and non-relapse mortality (NRM) were 75.6%, 64.3%, 24.7£¥ and 13.7%, respectively, in all 30 MD patients; and 79.3%,73.8%,15.5% and 12.3% (Fig.2), respectively, in the 25 cases with complete remission (CR) at the time of transplantation. The corresponding data were 89% vs. 88.9%£¬65.0% vs. 77.8%£¬31.1 % vs.12.5% and 10.3% vs.11.1%£¨p>0.05 in all pairs), respectively, in hap-SC and UCB engrafted groups. Donor carrying KIR centromeric B motif was associated with reduced RI (10 % vs. 33.9%).In TM group, OS, thalassemia free survive (TFS), rejection and transplant-related mortality were 91.2%, 85.7%, 5.6% and 8.8%, respectively in all 36 patients. Impressively, all of the 26 patients who received the newer CT-14 protocol were alive without TM (Fig. 2). 7/10 UCB carrying KIR centromeric B motif engrafted.In the MD group, 23.3% had grade II-IV and10.0% had III-IV acute GVHD. Grade II, III and IV acute GVHD occurred in 3 patients, respectively, in TM group. One MD patient had severe chronic GVHD (lung) after DLI for relapse. No moderate chronic GVHD occurred in TM groups.SummaryThe CT-13 regimen resulted in high OS and DFS, especially in CR patients in the MD group. The CT-14 leaded to 100% TFS in thalassemia patients. Acute and chronic GVHD were acceptable. Donor carrying centromeric B motif promoted engraftment and reduced RI. A multicenter study should be developed in the future based on our favorable results. [Display omitted] [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Decentralized Manufacture of TCR-Alpha/Beta and CD19 Depleted Haploidentical Stem Cell Grafts for Children within a Multicenter Phase I/II Clinical Trial

Several single center experiences have shown favorable outcomes using in-vitro depletion of T cell receptor (TCR)-alpha/beta cells and B cells.For the first time we show the manufacturing results of stem cell grafts from haploidentical family donors for 30 pediatric patients with various hematological and non-hematological malignancies and non-malignant diseases within a prospective, multi-center phase I/II clinical trial utilizing the CliniMACS plus System (Miltenyi Biotec, Germany) in combination with a reduced conditioning (www.clinicaltrialsregister.org; 2011-005562-38). The in-vitro T cell depletions of the grafts were performed by four different laboratories under fixed conditions. The grafts were sent to six treatment centers.Methods: Donors received G-CSF for mobilization of stem cells according to local hospital routine followed by leukaphereses that were depleted from TCRab+ and CD19+ cells according to manufacturer's instructions (CliniMACS plus System, Miltenyi Biotec) and as approved by local authorities. For quality purposes the sponsor performed regularly round robin tests to ensure provision of comparable results regarding the residual number of TCRab+ cells in the grafts.The transplants should be composed of a maximum of 7.5 x 108 nucleated cells/mL with targeted ≥ 4 x 106 CD34+ cells/kg, ≤ 25 x 103 TCRab+ cells/kg, ≤ 1 x 105 CD20+ cells/kg and a CD34+ cell viability of ≥ 95%. In case the targeted value for CD34+ cells/kg was not reached, the number of TCRab+ cells/kg was allowed to exceed by up to the four-fold until 4 x 106 CD34+ cells/kg per transplant have been isolated. One transplant could consist of up to three single aphereses depleted of TCRab+ and CD19+ cells. These products were to be infused directly after separation or following cryopreservation. Pooling of aphereses from a single donor was not allowed.Results: 30 pediatric patients, median age 7 years (range, 1 - 17 years) received a total of 43 TCRab/CD19 depleted haploidentical stem cell products. 17 patients got one infusion, 11 two and one patient three infusions. The stem cell products contained in median 9.46 x 106/kg (range, 1.35 - 54.9) CD34+ cells, 8.4 x 103/kg (range, 0.62 - 40.6) TCRab+ cells and 0.32 x 105/kg (range, 0.037 - 1.7) CD20+ cells. Log depletion for TCRab+ cells and B cells was 4.75 (range, 1.2 - 5.33) and 3.43 (range, 0 - 3.93), respectively. In addition significant numbers of NK and TCRgd+ cells/kg were preserved: 3.9 x 107 (median; range, 0.11 - 18.2), 0.67 x 107 (median; range, 0.05 - 4.0), respectively, summing up to a median number of 6.99 x 106(range, 0.42 - 39.7) total CD3+ cells/kg. Viability of CD34+ cells was 97.9% (median, range 91.5 - 100).All patients received transplants (consisting of up to three single consecutive products) with the targeted CD34+ cell dose - median 14.6 x 106 cells/kg (range, 4 - 54.9) and with less than the maximal allowed number of 1x105 TCRab+ cells/kg. Three single products exceeded targeted TCRab cell numbers but remained within the defined limit of the transplant of 1 x 105 cells/kg in order to meet the specification of ≥ 4 x 106 CD34+ cells/kg. In six single products the B cell numbers were above the specified targeted limit (max. 1.7 x 105/kg). Four products had a viability of CD34+ cells between 91.5 and 95%.Of 30 treated patients no patient experienced acute GVHD°III-IV. Only one patient had acute GVHD°II. The transplant of this patient fulfilled the targeted specifications for total CD34+, TCRab+ and CD20+ cells/kg.Round robin tests were performed prior to study start and during the enrollment period. The identified issues were addressed prior to study start and subsequent tests revealed a uniform performance of the manufacturing centers.Conclusion: 43 stem cell products were manufactured and released by 4 manufacturing laboratories for 30 pediatric patients in 6 hospitals within a clinical study investigating TCR alpha/beta and CD19 depleted haploidentical stem cell transplantation after reduced intensity conditioning. A highly effective depletion of TCRab + cells and B cells with comparable results was shown in all laboratories as controlled by frequent evaluation in round robin tests. Limited exceedances of the targeted release criteria of TCRa/b+ cells were acceptable to the physicians and had no clinical impact. DisclosuresBönig:Miltenyi Biotec: Consultancy, Honoraria, Research Funding. Bader:Riemser: Research Funding; Neovii Biotech: Research Funding; Servier: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Medac: Consultancy, Research Funding. Aktas:Miltenyi Biotec: Employment. Dresing:Miltenyi Biotec: Employment. Karitzky:Miltenyi Biotec: Employment. Holtkamp:Miltenyi Biotec: Employment. Handgretinger:Miltenyi Biotec: Patents & Royalties: Co-Patentholder of TcRalpha/beta depletion technology.

TCR-Alpha/Beta and CD19 Depleted Haploidentical Stem Cell Transplantation Following Reduced Intensity Conditioning in Children: First Results of a Prospective Multicenter Phase I/II Clinical Trial

We report the first prospective, multi-center, open-label, single-arm phase I/II clinical trial that assesses the safety and feasibility of stem cell transplantation with TCRalpha/beta and CD19-depleted haploidentical grafts generated with the CliniMACS plus System (Miltenyi Biotec, Germany) in combination with a reduced-intensity conditioning in pediatric patients suffering from various malignant and non-malignant diseases (www.clinicaltrialsregister.org; 2011-005562-38). All patients received single agent MMF as short-term GVHD prophylaxis (40mg/kg/day for 30 days). The speed of immune reconstitution was measured in two core labs using standardized methods and the MACSQuant flow cytometry device (Miltenyi Biotec, Germany).Results: Thirty patients from six hospitals were treated (13 female, 17 male; median age 7 years, range 1 - 17 years). Of the 30 recipients, 10 had ALL, 8 had AML, 6 had solid tumors (soft tissue sarcomas and neuroblastomas), 3 had MDS/MPS, and 1 each with lysosomal storage disorder, SCID, and Wiskott Aldrich syndrome. Disease status in acute leukemias/MDS was: CR1 (n=4), relapsed/refractory (n=17). 5/6 patients with solid tumors had relapsed metastatic disease. The conditioning regimen consisted of 15 or 30 mg ATG (Fresenius/Grafalon) or 7 Gy total nodal irradiation, 160 mg/m2 fludarabine, 10 mg/kg thiotepa, and 140 mg/m2 melphalan. The median number of CD34+ cells, TCRalpha/beta+ cells and CD20+ cells infused was 14.6 x 106 (range, 4 - 54.9), 14 x 103 (range, 0.62 - 40.6) and 0.55 x 105 (range, 0.04 - 1.85), respectively. In addition, significant numbers of NK and TCRgd+ cells/kg were infused - 6.67 x 107 (median; range, 0.68 - 18.2) and 1.58 x 107 (median; range, 0.13 - 4.7), respectively. All 30 patients tolerated the infusion of haploidentical stem cell grafts well. Twenty-five patients had primary engraftment of ANC > 500 cells/µL at a median of 12 days (range, 10 - 18) and PLT > 20,000 cells/µL at a median of 15 days (range, 11 - 27). Peripheral T-cell chimerism at the time of engraftment was completely donor in 19/25 patients (76%), mixed in 3 (12%), and not measured in three. Five patients experienced primary graft failure and 2 had secondary graft failure. All except of one were successfully re-transplanted.None of the recipients developed severe acute GVHD grades III - IV. Only 1 patient had acute GVHD grade II that started on day 22. The vast majority of patients (96.7%) experienced no or only grade I acute GVHD despite minimal GVHD prophylaxis after transplantation.Samples from 24/25 patients with primary engraftment were evaluable for immune reconstitution (Figure 1). On day 28, the majority of WBC were NK cells (median 309 cells/µL; range, 64 - 1026). The second main type of cells were CD3+ cells (median 151 cells/µL; range, 9 - 953), mostly TCRgd+ (median 87 cells/µL; range, 7 - 891). At day 100, TCRab+ cells equalled TCgd+ cells (median 108 vs. 116 cells/µL). B cells recovered more slowly, with a median of 255.5 cells/µL (range, 1 - 1218) on day 63.ADV reactivation contributed most to infectious complications following transplantation. In total, 16/30 patients had ADV DNAemia or were positive in stool. Additionally, seven patients were tested positive for CMV (blood or urine). BK virus was present in 5 patients with 3 patients experiencing cystitis. No EBV reactivation was observed. Two patients had bacterial sepsis, 1 moderate, 1 fatal (due to non-engraftment).No fatal viral infection occurred within 100 days.One molecular relapse was observed within 100 days post transplantation that was treated with blinatumomab. Two of the 30 transplanted patients died within 100 days after transplantation: 1 patient due to sepsis following graft failure (non-relapse mortality) and 1 due to relapse. On day 100, chimerism was completely donor in 20 patients and mixed in two.Conclusions: The CliniMACS depletion system of TCRab+ and CD19+ cells yielded a large number of CD34+ cells, NK cells and TCRgd+ cells, that could be infused safely into pediatric patients with minimal risk of severe acute GVHD. The immune reconstitution was rapid and there was no TRM associated with viral or fungal infections. Coupled with a reduced-intensity regimen, the overall TRM was low. Longer follow up will provide essential information on chronic GVHD and survival outcomes. [Display omitted] DisclosuresBader:Riemser: Research Funding; Neovii Biotech: Research Funding; Servier: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Medac: Consultancy, Research Funding. Karitzky:Miltenyi Biotec: Employment. Holtkamp:Miltenyi Biotec: Employment. Siewert:Miltenyi Biotec: Employment. Bönig:Miltenyi Biotec: Consultancy, Honoraria, Research Funding. Handgretinger:Miltenyi Biotec: Patents & Royalties: Co-Patentholder of TcRalpha/beta depletion technology.

Mobilization of healthy donors with plerixafor affects the cellular composition of T-cell receptor (TCR)-αβ/CD19-depleted haploidentical stem cell grafts.

BackgroundHLA-haploidentical hematopoietic stem cell transplantation (HSCT) is suitable for patients lacking related or unrelated HLA-matched donors. Herein, we investigated whether plerixafor (MZ), as an adjunct to G-CSF, facilitated the collection of mega-doses of hematopoietic stem cells (HSC) for TCR-αβ/CD19-depleted haploidentical HSCT, and how this agent affects the cellular graft composition.MethodsNinety healthy donors were evaluated. Single-dose MZ was given to 30 ‘poor mobilizers’ (PM) failing to attain ≥40 CD34+ HSCs/μL after 4 daily G-CSF doses and/or with predicted apheresis yields ≤12.0x106 CD34+ cells/kg recipient’s body weight.ResultsMZ significantly increased CD34+ counts in PM. Naïve/memory T and B cells, as well as natural killer (NK) cells, myeloid/plasmacytoid dendritic cells (DCs), were unchanged compared with baseline. MZ did not further promote the G-CSF-induced mobilization of CD16+ monocytes and the down-regulation of IFN-γ production by T cells. HSC grafts harvested after G-CSF + MZ were enriched in myeloid and plasmacytoid DCs, but contained low numbers of pro-inflammatory 6-sulfo-LacNAc+ (Slan)-DCs. Finally, children transplanted with G-CSF + MZ-mobilized grafts received greater numbers of monocytes, myeloid and plasmacytoid DCs, but lower numbers of NK cells, NK-like T cells and Slan-DCs.ConclusionsMZ facilitates the collection of mega-doses of CD34+ HSCs for haploidentical HSCT, while affecting graft composition.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-014-0240-z) contains supplementary material, which is available to authorized users.

Combination of a haploidentical SCT with an unrelated cord blood unit: a single-arm prospective study

We conducted a single-arm prospective study in 50 patients who received the combination of an haploidentical stem cell graft and an unrelated umbilical cord blood unit for the treatment of hematological malignancies. The median time for neutrophil engraftment was 13 days (11-20 days), and for platelets was 15 days (11-180 days). All surviving patients attained complete haploidentical engraftment except three patients who presented a mixed engraftment with increasing cord blood and decreasing haplo mismatch chimerism during the first 4 months after transplantation. The cumulative incidence of grade II-IV acute GVHD was 20%±0.327% at day+100, and the incidence of chronic GVHD was 19.26%±1.0% at 1 year. The 1-year cumulative incidence of relapse was 19.78%±1%, and the TRM was 16.2%±0.54%. At 1 year, overall survival was 78.6%±7.6% and PFS 64.0%±11.0%. The BU/CY-based conditional regimen showed a significant superiority over TBI/CY on PFS (relative risk=5.012, 95% confidence interval, 1.146-21.927, P=0.032). In conclusion, the co-infusion of an unrelated cord blood unit may potentially improve the outcome of haploidentical allogeneic hematopoietic SCT.

EBV-induced post transplant lymphoproliferative disorders: a persisting challenge in allogeneic hematopoetic SCT

EBV-induced post transplantation lymphoproliferative disorder (EBV-PTLD) is a life-threatening complication after allogeneic hematopoietic cell transplantation. Profound T-cell depletion of the allograft represents a major risk factor for EBV-PTLD. With regard to the increasing use of alternative stem cell sources such as cord blood or purified haploidentical stem cell grafts both associated with impaired immune reconstitution, the frequent occurrence of EBV-PTLD demands particular vigilance on laboratory changes and early symptoms. Here we have summarized today's knowledge about EBV-PTLD in a comprehensive review explaining the underlying mechanisms of EBV-based transformation, EBV-PTLD development, clinical presentation, incidence, diagnosis, screening, therapy and prognosis. In this context, we emphasize on the necessity of regularly applied screening tools and pre-emptive treatment strategies including anti-CD20 Abs particularly in high-risk patients to avoid disease progression to malignant lymphoma. Although EBV-PTLD has always been associated with a high mortality rate, novel immunotherapeutic approaches such as the transfer of EBV-specific T cells nowadays offer improved chances of disease control even at late stages.

Development of gammadelta T-cell receptor repertoire after TCRab/CD19 depleted haploidentical stem cell transplantation in children (P2190)

Abstract Recent advances in stem cell manipulation techniques have allowed to optimize cellular composition of HLA-mismatched haploidentical stem cell grafts. We analyzed immune and haematopoietic reconstitution in 4 children transplanted with TCRab/CD19-depleted haploidentical stem cell grafts with a special emphasis on gammadelta-T-cell reconstitution. Grafts consisted of 8.5x10e6 CD34/kg, 8.8x10e4 CD3TCRab+/kg, 8.8x10e6 CD3TCRgd+/kg, and 17.5x10e6 CD16+CD56+/kg BW. Haematopoietic reconstitution was rapid in all patients. T-cell counts reached &amp;gt;100/µl after a median of 34 days, 75% of these expressing the gd-TCR. The predominance of gd-T-cells decreased and by day +100 50% of T-cells were positive for the gd-TCR and 46% for the ab-TCR. Gd-TCR Immunoscope analysis revealed the molecular composition of the gd-population: the Vg9-chain was expressed by a median of 54%, Vg2 by 17.6% of gd-T-cells, the remaining Vg-chains by less than 10%, respectively. Vd4-expressing subclones made up 53% of the whole gd-TCR-repertoire, followed by 33.4% Vd2+ subclones. Distribution of gd-subclones was relatively stable over time, so that the contraction of the gd-T-cell population could not be attributed to the disappearance of specific Vg- or Vd families. These data provide new insight into the T-cell reconstitution kinetics after TCRab/CD19-depleted transplantation.

Improved T Cell Recovery After Transplantation Of CD3/CD19 Depleted Haploidentical Stem Cell Grafts In Pediatric Patients

Improved T Cell Recovery After Transplantation Of CD3/CD19 Depleted Haploidentical Stem Cell Grafts In Pediatric Patients

Improved T Cell Recovery After Transplantation of CD3/CD19 depleted Haploidentical Stem Cell Grafts in Pediatric Patients.

Abstract 4652Profound depletion of T and B cells is a fundamental prerequisite for haploidentical transplantation and allows to minimize GvHD despite HLA incompatibility. However, posttransplant recovery of donor derived T cells is delayed after various graft manipulation procedures and may result in severe infections. Methods to improve this recovery are of great importance. Here we present immune reconstitution data in patients who received CD3/CD19 depleted stem cells in combination with melphalan based or standard conditioning regimens.32 patients with ALL (n=14), AML/MDS (n=17), CML (n=1) were included. T and B cells were directly depleted using antiCD3/antiCD19 coated magnetic microbeads and the CliniMACSTM device.The patients received either TBI or Bu i.v. and OKT3 (n=9) or a reduced intensity conditioning (“RIC”: Mel 140mg/m2, Flud 160mg/m2, TT 10mg/kg, OKT3, n= 23).Absolute numbers of lymphocyte subsets per microliter on day 90 were compared within these both groups and with a historical control group (patients with leukemias who received CD34 selected grafts and TBI or Bu based standard conditioning regimen in combination with ATG, n=28).CD3+4+, CD3+8+ and total numbers of CD3+ of patients after CD3/CD19 depletion were significantly higher in the RIC-group than in the TBI/Bu-group (mean numbers: 85.83 vs. 38.84; 133.46 vs. 19.69; 270.27 vs. 63.99; p<0.05, unpaired t-test).Comparison with the whole CD34 historical group showed a faster recovery of CD3+4+ in patients with CD3/19 depletion and RIC (104.26 vs. 54.22; p= 0,034) but no significant difference in CD3+8+ and CD3+. Furthermore, subgroups of the CD34 historical population were compared: patients with CD3/19 depletion and RIC had a significantly faster recovery of CD3+4+, CD3+8+ and CD3+ than CD34 patients with TBI (104.26vs. 25.48; 133.46vs. 43.17; 270.27 vs. 65.86; p<0.05) but had no advantage over CD34 patients with non-TBI conditioning.Conclusions: the type of graft manipulation appeared to have an influence on the speed of CD4+ recovery (CD3/19 depletion > CD34 selection). Moreover, the use of TBI had a clear negative impact on all T cell subsets: patients with TBI had a slower recovery than patients with non-TBI conditioning, independent from graft manipulation procedures and probably due to thymic damage. Thus, the use of RIC-protocols in combination with CD3/CD19 depletion may help to speed up the immune recovery after haploidentical transplantation. Further studies are warranted to evaluate the risk of relapse. Disclosures:No relevant conflicts of interest to declare.

Cytotoxic T lymphocyte therapy with donor T cells prevents and treats adenovirus and Epstein-Barr virus infections after haploidentical and matched unrelated stem cell transplantation

AbstractViral infection or reactivation remains a major cause of morbidity and mortality after allogeneic stem cell transplantation. We now show that infusions of single cytotoxic T lymphocyte (CTL) lines (5 × 106-1.35 × 108 cells/m2) with specificity for 2 commonly detected viruses, Epstein-Barr virus (EBV) and adenovirus, can be safely administered to pediatric transplantation recipients receiving partially human leukocyte antigen–matched and haploidentical stem cell grafts (n = 13), without inducing graft-versus-host disease. The EBV-specific component of the CTLs expanded in vivo and persisted for more than 12 weeks, but the adenovirus-specific component only expanded in vivo in the presence of concomitant adenoviral infection. Nevertheless, adenovirus-specific T cells could be detected for at least 8 weeks in peripheral blood, even in CTL recipients without viral infection, provided the adenovirus-specific component of their circulating lymphocytes was first expanded by exposure to adenoviral antigens ex vivo. After infusion, none of these 13 high-risk recipients developed EBV-associated lymphoproliferative disease, while 2 of the subjects had resolution of their adenoviral disease. Hence, bispecific CTLs containing both EBV- and adenovirus-specific T cells can safely reconstitute an antigen responsive “memory” population of CTLs after human leukocyte antigen–mismatched stem cell transplantation and may provide antiviral activity. This trial was registered at www.clinicaltrials.gov as #NCT00590083.

Rapid Immune Reconstitution after a Reduced-Intensity Conditioning Regimen and a CD3-Depleted Haploidentical Stem Cell Graft for Pediatric Refractory Hematologic Malignancies.

Haploidentical hematopoietic stem cell transplantation (HaploHSCT) from a mismatched family member (MMFM) donor offers an alternative option for patients who lack an HLA-matched donor. The main obstacles to successful haploidentical hematopoietic stem cell transplantation from a mismatched family member donor are delayed immune reconstitution, vulnerability to infections, and severe graft-versus-host disease (GvHD).Method: We designed a reduced-intensity conditioning regimen that excluded total body irradiation and anti-thymocyte globulin. The graft was immunomagnetically depleted of CD3+ T-cells (CD3 negative selection) and contained a large number of both CD34+ and CD34− stem cells and most other immune cells especailly NK cells. This protocol was used to treat 22 pediatric patients with refractory hematologic malignancies.Results and Discussion: After transplantation, 91% of the patients achieved full donor chimerism. They also showed rapid recovery of CD3+ T-cells, T-cell receptor excision circle counts, TCRβ repertoire diversity and NK-cells during first four months post-transplantation. The incidence and extent of viremia were limited and no lethal infection was seen. Only 9% of patients had grade 3 acute GvHD, while 27% patients had grade 1 and another 27% had grade 2 acute GvHD. This well-tolerated regimen appears to accelerate immune recovery and shorten the duration of early post-transplant immunodeficiency, thereby reducing susceptibility to viral infections. Rapid T-cell reconstitution, retention of NK-cells in the graft, and induction of low grade GvHD may also enhance the potential anti-cancer immune effect.

Rapid immune reconstitution after a reduced‐intensity conditioning regimen and a CD3‐depleted haploidentical stem cell graft for paediatric refractory haematological malignancies

The main obstacles to successful haploidentical haematopoietic stem cell transplantation from a mismatched family member donor are delayed immune reconstitution, vulnerability to infections and severe graft-versus-host disease (GvHD). We designed a reduced-intensity conditioning regimen that excluded total body irradiation and anti-thymocyte globulin in order to expedite immune reconstitution after a CD3-depleted haploidentical stem cell transplant. This protocol was used to treat 22 paediatric patients with refractory haematological malignancies. After transplantation, 91% of the patients achieved full donor chimaerism. They also showed rapid recovery of CD3(+) T-cells, T-cell receptor (TCR) excision circle counts, TCRbeta repertoire diversity and natural killer (NK)-cells during the first 4 months post-transplantation, compared with those results from a group of patients treated with a myeloablative conditioning regimen. The incidence and extent of viremia were limited and no lethal infection was seen. Only 9% of patients had grade 3 acute GvHD, while 27% patients had grade 1 and another 27% had grade 2 acute GvHD. This well-tolerated regimen appears to accelerate immune recovery and shorten the duration of early post-transplant immunodeficiency, thereby reducing susceptibility to viral infections. Rapid T-cell reconstitution, retention of NK-cells in the graft and induction of low grade GvHD may also enhance the potential anti-cancer immune effect.