scholarly journals Early and Transient Microchimerism Associated with Complete Remission after Adoptively Transferred Haploidentical NK Cells Against High Risk Myelodysplastic Syndrome and Refractory Acute Myeloid Leukemia

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1120-1120
Author(s):  
Andreas T Björklund ◽  
Mattias Carlsten ◽  
Marie Schaffer ◽  
Lisa Liu ◽  
Sarah A. Cooley ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
High Risk ◽  
Nk Cells ◽  
Myeloid Leukemia ◽  
Progressive Disease ◽  
Nk Cell ◽  
Nk Cell Therapy ◽  
Acute Myeloid

Abstract Introduction: We here report from an ongoing phase I/II study of HLA-haploidentical NK cell therapy to patients with high-risk myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) not eligible for standard therapies. The preparative regimen consisted of intermediate doses of Cyklophosphamide (Cy), Fludarabin (Flu) and titrated doses of total lymphoid irradiation (TLI). The trial design excluded systemic IL-2 treatment to avoid expansion of regulatory T cells and to test if in vivo expansion could be obtained without IL-2 support. Patients:The first 12 patients were treated with Cy/Flu and an escalating dose of TLI (2 Gy and 4 Gy), followed by infusion of short-term IL-2 activated (16 hours) NK cells. Three patients received daily cyclosporine A after the conditioning. Three had relapsed, chemotherapy-refractory, primary AML, seven had secondary relapsed or refractory MDS-AML and two had high risk MDS with fibrosis. Results: The treatment was well tolerated and no severe non-infectious toxicity could be observed in the patients. The endpoint of expansion (>100 donor NK cells/ul at day 14) was not reached, but six patients had positive microchimerism, NK cells of donor origin detectable by RT-PCR at day 7-14, that thereafter became undetectable within 7-14 days. Four of these six patients achieved complete remission (CR) whereafter they become eligible for and could proceed to allogeneic stem cell transplantation. None of the patients with negative microchimerism obtained CR. Four patients died from progressive disease and three patients, with minor response and progressive disease, died in infections within three months of therapy. Discussion: Although the long-term efficacy needs to be evaluated, the results suggest that a combined regimen with mild conditioning followed by NK cell therapy may induce remission in patients with chemo-refractory disease and provide a bridge to allogeneic stem cell transplantation. Notably, clinical responses were observed after only a minimal in vivo NK cell expansion and were independent on KIR-ligand mismatch. Disclosures Blomberg: VECURA: Employment. Hellström-Lindberg:Celgene: Research Funding.

Successful transfer of alloreactive haploidentical KIR ligand-mismatched natural killer cells after infusion in elderly high risk acute myeloid leukemia patients

Blood ◽  
2011 ◽  
Vol 118 (12) ◽  
pp. 3273-3279 ◽  
Author(s):  
Antonio Curti ◽  
Loredana Ruggeri ◽  
Alessandra D'Addio ◽  
Andrea Bontadini ◽  
Elisa Dan ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
High Risk ◽  
Nk Cells ◽  
Natural Killer ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Median Number ◽  
Active Disease ◽  
Acute Myeloid

Abstract Thirteen patients with acute myeloid leukemia, 5 with active disease, 2 in molecular relapse, and 6 in morphologic complete remission (CR; median age, 62 years; range, 53-73 years) received highly purified CD56+CD3− natural killer (NK) cells from haploidentical killer immunoglobulin-like receptor–ligand mismatched donors after fludarabine/cyclophosphamide immunosuppressive chemotherapy, followed by IL-2. The median number of infused NK cells was 2.74 × 106/Kg. T cells were < 105/Kg. No NK cell–related toxicity, including GVHD, was observed. One of the 5 patients with active disease achieved transient CR, whereas 4 of 5 patients had no clinical benefit. Both patients in molecular relapse achieved CR that lasted for 9 and 4 months, respectively. Three of 6 patients in CR are disease free after 34, 32, and 18 months. After infusion, donor NK cells were found in the peripheral blood of all evaluable patients (peak value on day 10). They were also detected in BM in some cases. Donor-versus-recipient alloreactive NK cells were shown in vivo by the detection of donor-derived NK clones that killed recipient's targets. Adoptively transferred NK cells were alloreactive against recipient's cells, including leukemia. In conclusion, infusion of purified NK cells is feasible in elderly patients with high-risk acute myeloid leukemia. This trial was registered at www.clinicaltrial.gov as NCT00799799.

scholarly journals 852 Trifunctional NKp46/CD16a-NK cell engager targeting CD123 overcomes acute myeloid leukemia resistance to ADCC

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A893-A893
Author(s):  
Laurent Gauthier ◽  
Angela Virone-Oddos ◽  
Angela Virone-Oddos ◽  
Jochen Beninga ◽  
Benjamin Rossi ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Antitumor Activity ◽  
Nk Cells ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Ex Vivo ◽  
Activating Receptors ◽  
Acute Myeloid

BackgroundThere is a clear need for targeted therapies to treat acute myeloid leukemia (AML), the most common acute leukemia in adults. CD123 (IL-3 receptor alpha chain) is an attractive target for AML treatment.1 However, cytotoxic antibody targeting CD123 proved insufficiently effective in a combination setting in phase II/III clinical trials.2 T-cell engagers targeting CD123 displayed some clinical efficacy but were often associated with cytokine release syndrome and neurotoxicity.3 Interest in the use of NK cells for therapeutic interventions has increased in recent years, as a potential safer alternative to T cells. Several NK-cell activating receptors, such as CD16a, NKG2D, and the natural cytotoxicity receptors NKp30 and NKp46, can be targeted to induce antitumor immunity. We previously reported the development of trifunctional NK-cell engagers (NKCEs) targeting a tumor antigen on cancer cells and co-engaging NKp46 and CD16a on NK cells.4MethodsWe report here the design, characterization and preclinical development of a novel trifunctional NK cell engager (NKCE) targeting CD123 on AML cells and engaging the activating receptors NKp46 and CD16a on NK cells. The CD123 NKCE therapeutic molecule was engineered with humanized antibodies targeting NKp464 and CD123.5 We compared CD123-NKCE and a cytotoxic ADCC-enhanced antibody (Ab) targeting CD123, in terms of antitumor activity in vitro, ex vivo and in vivo. Pharmacokinetic, pharmacodynamic and safety profile of CD123-NKCE were evaluated in non-human primate (NHP) studies.ResultsThe expression of the high affinity Fc gamma receptor CD64 on patient-derived AML cells inhibited the ADCC of the Ab targeting CD123 in vitro and ex vivo, but not the antitumor activity of CD123-NKCE. CD123-NKCE had potent antitumor activity against primary AML blasts and AML cell lines, promoted strong NK-cell activation and induced cytokine secretion only in the presence of AML target cells. Its antitumor activity in mouse model was greater than that of the comparator antibody. Moreover, CD123-NKCE had strong and prolonged pharmacodynamic effects in NHP when used at very low doses, was well-tolerated up to high 3 mg/kg dose and triggered only minor cytokine release.ConclusionsThe data for activity, safety, pharmacokinetics, and pharmacodynamics provided here demonstrate the superiority of CD123-NKCE over comparator cytotoxic antibody, in terms of antitumor activity in vitro, ex vivo, in vivo, and its favorable safety profile, as compared to T-cell therapies. These results constitute proof-of-principle for the efficacy of CD123-NKCE for controlling AML tumors in vivo, and provide consistent support for their clinical development.ReferencesEhninger A, Kramer M, Rollig C, et al. Distribution and levels of cell surface expression of CD33 and CD123 in acute myeloid leukemia. Blood Cancer J 2014;4:e218.Montesinos P, Gail J Roboz GJ, et al. Safety and efficacy of talacotuzumab plus decitabine or decitabine alone in patients with acute myeloid leukemia not eligible for chemotherapy: results from a multicenter, randomized, phase 2/3 study. Leukemia 2021;35(1):62–74.Uy GL, Aldoss I, Foster MC, et al. Flotetuzumab as salvage immunotherapy for refractory acute myeloid leukemia. Blood 2021;137(6):751–762.Gauthier L, Morel A, Anceriz N, et al. Multifunctional natural killer cell engagers targeting NKp46 trigger protective tumor immunity. Cell 2019;177(7):1701–13.Jin L, Lee EM, Ramshaw HS, et al. Monoclonal antibody-mediated targeting of CD123, IL-3 receptor alpha chain, eliminates human acute myeloid leukemic stem cells. Cell Stem Cell 2009;5:31–42.

Adoptive Immunotherapy with Haploidentical Kir Ligand-Mismatched Natural Killer Cells In Elderly High Risk Acute Myeloid Leukemia Patients: Biological and Clinical Results of A Pilot Study

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4287-4287
Author(s):  
Antonio Curti ◽  
Loredana Ruggeri ◽  
Alessandra D'Addio ◽  
Andrea Bontadini ◽  
Valeria Giudice ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
High Risk ◽  
Nk Cells ◽  
Natural Killer ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Interleukin 2 ◽  
Active Disease ◽  
Acute Myeloid

Abstract Abstract 4287 Purpose: To evaluate safety, feasibility and anti-leukemia potential of haploidentical KIR-L mismatched natural killer (NK) cell infusion in elderly high risk acute myeloid leukemia (AML) patients. Patients and Methods: Thirteen patients (5 active disease, 2 molecular relapse and 6 complete remissions) with median age 62 years (range 53–73) received NK cell infusion after immunosuppressive chemotherapy (fludarabine/cyclophosphamide), followed by interleukin-2. Highly purified CD56+CD3- NK cells from haploidentical KIR-L mismatched donors were used. The median number of infused NK cells was 2.74 × 106/Kg. T cells were less than 105/Kg. NK cell chimerism, phenotyping, and functional assays were performed. Results: No significant toxicity, including graft versus host disease, related to NK cell infusion was observed. Among patients with active disease, 1/5 obtained transient complete remission (CR), whereas 4/5 patients had no clinical benefit. Both patients in molecular relapse obtained CR, which lasted 9 and 4 months. Three/6 patients in morphologic CR are disease-free after 34, 32 and 18 months. Donor NK cells were demonstrated in the peripheral blood (PB) of all evaluable patients with a peak at day 10 after infusion and, in some cases, also in the bone marrow (BM). NK alloreactivity was demonstrated in vivo by the detection of donor-derived postinfusion NK clones capable of killing recipient targets. Conclusion: Infusion of purified CD56+CD3- NK cells is feasible and safe in elderly high risk AML patients. Adoptively transferred NK cells, which can be detected in PB and BM after infusion, are alloreactive against recipient cells and may induce an anti-leukemic activity. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Acute Myeloid Leukemia Epigenetic Immune Escape From Nature Killer Cells by ICAM-1

2021 ◽  
Vol 11 ◽  
Author(s):  
Yang Xiao ◽  
Jinghong Chen ◽  
Jia Wang ◽  
Wei Guan ◽  
Mengzhen Wang ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Nk Cells ◽  
Myeloid Leukemia ◽  
Immune Escape ◽  
Nk Cell ◽  
Epigenetic Modification ◽  
Intercellular Adhesion Molecule ◽  
Intercellular Adhesion Molecule 1 ◽  
Acute Myeloid

Acute myeloid leukemia (AML), a malignant disorder of hemopoietic stem cells. AML can escape immunosurveillance of natural killer (NK) by gene mutation, fusions, and epigenetic modification, while the mechanism is not clearly understood. Here we show that the expression of Intercellular adhesion molecule‐1 (ICAM‐1, CD54) is silenced in AML cells. Decitabine could upregulate ICAM-1 expression, which contributes to the NK-AML cell conjugates and helps NK cells kill AML cells. We also show that ICAM-1 high expression can reverse the AML immune evasion and activate NK cells function in vivo. This study suggests that a combination of the hypomethylating agent and NK cell infusion could be a new strategy to cure AML.

scholarly journals CD38 knockout natural killer cells expressing an affinity optimized CD38 chimeric antigen receptor successfully target acute myeloid leukemia with reduced effector cell fratricide.

Haematologica ◽  
2020 ◽  
Author(s):  
Mark Gurney ◽  
Arwen Stikvoort ◽  
Emma Nolan ◽  
Lucy Kirkham-McCarthy ◽  
Stanislav Khoruzhenko ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Cell Therapy ◽  
Nk Cells ◽  
Natural Killer ◽  
Chimeric Antigen Receptor ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Cd38 Expression ◽  
Nk Cell Therapy ◽  
Acute Myeloid

There is a strong biological rationale for the augmentation of allogeneic natural killer (NK) cell therapies with a chimeric antigen receptor (CAR) to enhance acute myeloid leukemia (AML) targeting. CD38 is an established immunotherapeutic target in multiple myeloma and under investigation as a target antigen in AML. CD38 expression on NK cells and its further induction during ex vivo NK cell expansion represents a barrier to the development of a CD38 CAR-NK cell therapy. We set out to develop a CD38 CAR-NK cell therapy for AML, first by using an NK cell line which has low baseline CD38 expression and subsequently healthy donor expanded NK cells. To overcome anticipated fratricide due to NK cell CD38 expression when using primary expanded NK cells, we applied CRISPR/Cas9 genome editing to disrupt the CD38 gene during expansion achieving a mean knockdown efficiency of 84%. The resulting CD38 KD expanded NK cells, after expression of an affinity optimized CD38 CAR, showed reduced NK cell fratricide and an enhanced ability to target primary AML blasts. Furthermore, the cytotoxic potential of CD38 CAR-NK cells was augmented by pre-treatment of the AML cells with all-trans retinoic acid which drove enhanced CD38 expression offering a rational combination therapy. These findings support the further investigation of CD38 KD - CD38 CAR-NK cells as a viable immunotherapeutic approach to the treatment of AML.

scholarly journals Role of Polymorphisms of NKG2D Receptor and Its Ligands in Acute Myeloid Leukemia and Human Stem Cell Transplantation

2021 ◽  
Vol 12 ◽  
Author(s):  
Alena Machuldova ◽  
Monika Holubova ◽  
Valentina S. Caputo ◽  
Miroslava Cedikova ◽  
Pavel Jindra ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Stem Cell Transplantation ◽  
Nk Cells ◽  
Cell Transplantation ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Nkg2d Receptor ◽  
Acute Myeloid

Natural killer cells possess key regulatory function in various malignant diseases, including acute myeloid leukemia. NK cell activity is driven by signals received through ligands binding activating or inhibitory receptors. Their activity towards elimination of transformed or virally infected cells can be mediated through MICA, MICB and ULBP ligands binding the activating receptor NKG2D. Given the efficiency of NK cells, potential target cells developed multiple protecting mechanisms to overcome NK cells killing on various levels of biogenesis of NKG2D ligands. Targeted cells can degrade ligand transcripts via microRNAs or modify them at protein level to prevent their presence at cell surface via shedding, with added benefit of shed ligands to desensitize NKG2D receptor and avert the threat of destruction via NK cells. NK cells and their activity are also indispensable during hematopoietic stem cell transplantation, crucial treatment option for patients with malignant disease, including acute myeloid leukemia. Function of both NKG2D and its ligands is strongly affected by polymorphisms and particular allelic variants, as different alleles can play variable roles in ligand-receptor interaction, influencing NK cell function and HSCT outcome differently. For example, role of amino acid exchange at position 129 in MICA or at position 98 in MICB, as well as the role of other polymorphisms leading to different shedding of ligands, was described. Finally, match or mismatch between patient and donor in NKG2D ligands affect HSCT outcome. Having the information beyond standard HLA typing prior HSCT could be instrumental to find the best donor for the patient and to optimize effects of treatment by more precise patient-donor match. Here, we review recent research on the NKG2D/NKG2D ligand biology, their regulation, description of their polymorphisms across the populations of patients with AML and the influence of particular polymorphisms on HSCT outcome.

scholarly journals Natural Killer Immunotherapy for Minimal Residual Disease Eradication Following Allogeneic Hematopoietic Stem Cell Transplantation in Acute Myeloid Leukemia

2019 ◽  
Vol 20 (9) ◽  
pp. 2057 ◽  
Author(s):  
Norimichi Hattori ◽  
Tsuyoshi Nakamaki
Keyword(s):  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Hematopoietic Stem Cell Transplantation ◽  
Stem Cell Transplantation ◽  
Nk Cells ◽  
Natural Killer ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Hematopoietic Stem ◽  
Acute Myeloid

The most common cause of death in patients with acute myeloid leukemia (AML) who receive allogeneic hematopoietic stem cell transplantation (allo-HSCT) is AML relapse. Therefore, additive therapies post allo-HSCT have significant potential to prevent relapse. Natural killer (NK)-cell-based immunotherapies can be incorporated into the therapeutic armamentarium for the eradication of AML cells post allo-HSCT. In recent studies, NK cell-based immunotherapies, the use of adoptive NK cells, NK cells in combination with cytokines, immune checkpoint inhibitors, bispecific and trispecific killer cell engagers, and chimeric antigen receptor-engineered NK cells have all shown antitumor activity in AML patients. In this review, we will discuss the current strategies with these NK cell-based immunotherapies as possible therapies to cure AML patients post allo-HSCT. Additionally, we will discuss various means of immune escape in order to further understand the mechanism of NK cell-based immunotherapies against AML.

scholarly journals Adoptively Transferred Donor-Derived Cytokine Induced Memory-like NK Cells Persist and Induce Remission in Pediatric Patient with Relapsed Acute Myeloid Leukemia after Hematopoietic Cell Transplantation

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3307-3307
Author(s):  
Jeffrey J. Bednarski ◽  
Clare Zimmerman ◽  
Amanda F Cashen ◽  
Sweta Desai ◽  
Mark Foster ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Nk Cells ◽  
Myeloid Leukemia ◽  
Hematopoietic Cell Transplantation ◽  
Nk Cell ◽  
Ex Vivo ◽  
Salvage Chemotherapy ◽  
Acute Myeloid ◽  
Refractory Aml

Acute myeloid leukemia (AML) accounts for 18% of pediatric leukemias. For high-risk AML, standard treatment includes multi-agent chemotherapy followed allogeneic hematopoietic cell transplantation (HCT). Despite a high remission rate, 50% of patients relapse and have a poor prognosis with < 20% of patients surviving more than 3 years. Salvage chemotherapy alone or combined with donor lymphocyte infusions (DLI) have little curative potential, and new treatment strategies are needed for relapsed-refractory AML. Previous studies have shown that natural killer (NK) cells can be stimulated ex vivo with IL-12/15/18 to generate a memory-like phenotype with enhanced anti-leukemia effect. In adults with relapsed-refractory AML, adoptive transfer of MHC-haploidentical cytokine-induced memory-like (CIML or ML) NK cells induced remission in 54% of patients (PMID27655849). The infused donor ML NK cells expand in vivo but are rapidly eliminated following recovery of recipient T cells, providing a window of therapeutic activity of 2-3 weeks. We sought to test the safety and efficacy of ML NK cells for treatment of pediatric/young adult patients with post-HCT relapsed AML. We hypothesized that ML NK cells derived from the HCT donor would be well-tolerated, exhibit anti-leukemia activity, and expand with prolonged persistence following transfer into pediatric AML patients. Here, we report the results of the first pediatric patient treated on a phase I clinical trial using ML NK cell therapy for relapsed AML after allogeneic HCT (NCT03068819). Briefly, patients are treated with FLAG (fludarabine, cytarabine and granulocyte colony stimulating factor) salvage chemotherapy to reduce the bulk of AML and provide lymphodepletion for ML NK cell expansion. Two weeks after chemotherapy, a non-mobilized leukapheresis product is collected from the original HCT donor and processed into a T cell-based DLI and ML NK cells. The T cell DLI (1 x 106 T cells/kg) is immediately infused, and the ML NK cells are generated by stimulation with IL-12/15/18 ex vivo for 12-16 hours and then infused (10x106/kg). An 18-month-old male with infant AML had relapse of his leukemia 3 months after MHC-haploidentical HCT. Treatment with chemotherapy, including mitoxantrone and daunorubicin-cytarabine liposome, failed to induce remission. At the time of enrollment on the phase I trial, he had AML blasts in his bone marrow (Table 1). He was treated with FLAG chemotherapy followed by infusion of DLI and ML NK cells from the original haploidentical HCT donor. Assessment at 30 days, 3 months and 6 months post NK cell infusion showed complete remission with no evidence of leukemia and full donor engraftment. Remarkably, donor-derived ML NK cells expanded to 77% of donor lymphocytes on day 28 and still comprised 24% percent of lymphocytes at 6 months post infusion (Figure 1A-C). The expanded donor NK cell phenotype was consistent with ML NK cells (e.g., NKG2A+KIR+) utilizing CyTOF multidimensional analysis previously confirmed to identify ML NK cells (Figure 1D). The ML NK cells were functional as demonstrated by leukemia-triggered IFN-γ production immediately ex vivo from day 7-28 samples (Figure 1E-F). The patient's clinical course was complicated by mild gastrointestinal graft-versus-host disease that resolved with low-dose steroids and tociluzimab. These early results demonstrate proof-of-principle that adoptive transfer of donor-derived ML NK cells in combination with DLI is feasible and offers a novel immunotherapy option for patients with relapsed AML after HCT. Moreover, in this T and NK cell compatible immune environment post-HCT, donor ML NK cells expand and persist robustly in vivo for > 6 months without exogenous cytokine support and have potent anti-leukemic activity. Thus, ML NK cells are a cellular therapy platform to treat AML that has relapsed after allogeneic HCT. Disclosures Cashen: Celgene: Other: Speaker's Bureau; Seattle Genetics: Other: Speaker's Bureau; Novartis: Other: Speaker's Bureau. Fehniger:Horizon Pharma PLC: Other: Consultancy (Spouse); Cyto-Sen Therapeutics: Consultancy.

scholarly journals Haploidentical T-Repleted Stem Cell Transplantation (SCT) Has Comparable Survival to 10/10 and 9/10 Unrelated SCT in Poor-Cytogenetics Risk Acute Myeloid Leukemia in First Complete Remission: A Study on Behalf of the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT)

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 852-852
Author(s):  
Francesca Lorentino ◽  
Myriam Labopin ◽  
Fabio Ciceri ◽  
Massimo Bernardi ◽  
Jordi Esteve ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
High Risk ◽  
Complete Remission ◽  
Stem Cell Transplantation ◽  
Myeloid Leukemia ◽  
First Complete Remission ◽  
Risk Of Relapse ◽  
Acute Myeloid

Abstract Background: Allogeneic stem cell transplantation (SCT) is the most powerful therapy to prevent relapse in poor-cytogenetics risk acute myeloid leukemia (poorAML) patients (pts) in first complete remission (CR1). For pts who lack a matched related donor (MRD), SCT from an unrelated (UD) or alternative donor is indicated. Pts with poorAML and thus at high risk of relapse can theoretically benefit the most from SCT from haploidentical donors (HaploSCT), which is an attractive option as the time required to find a well-matched UD could be inacceptable. Several recent reports show comparable outcomes between HaploSCT and transplants from UD (Piemontese S, JHO 2017; Versluis J, Blood Advances 2017). Comparative studies able to include sufficient numbers of pts with poorAML in CR1 are limited; this prompted us to compare the outcomes of HaploSCT to those of 10/10 and 9/10 HLA-matched UD in this disease category. Methods: We retrospectively selected denovo poorAML pts in CR1 receiving T-repleted haplo (n=74), 10/10 UD (n=433) and 9/10 UD SCT (n=123) from 2007 to 2015 who were reported to the ALWP of EBMT Registry. PoorAML was defined as the presence of: complex karyotype (at least 3 structural abnormalities per clone); monosomal karyotype (1 autosomal monosomy plus 1 monosomy or structural abnormality); inv(3)/t(3;3); -5 or del(5q); -7 or abn(7q); t(v;11)(v;q23); abn(17p); t(6;9); t(9;22). Primary endpoints were leukemia-free survival (LFS) and overall survival (OS). Secondary endpoints were acute and chronic GVHD (aGVHD and cGVHD), relapse and nonrelapse mortality (NRM). Results: Main population characteristics are depicted in Table 1. Recipients of haplo-, 10/10 UD- and 9/10 UD-SCT were comparable concerning time from diagnosis to SCT and time from CR1 to SCT. HaploSCT more likely received bone marrow as stem cell source. In-vivo T cell depletion (TCD) with ATG was most likely adopted in UD-SCT, with a conversely increased use of high-dose post-transplant Cyclophosphamide as GvHD prophylaxis backbone in HaploSCT (65% Vs 3% for 10/10 UD and 2% for 9/10 UD, p&lt;10¯³). LFS and OS at 2 years were not significantly different between haploSCT, 10/10 UD SCT and 9/10 UD SCT (53±12% and 59±12%, 43±5% and 50±6%, 44±9% and 50±9%, respectively, p=0.5 and p=0.5, respectively). In Haplo-SCT, the 100-day cumulative incidence (CI) of grade≥2 aGvHD was in line with the one reported for 10/10 and 9/10 UD (33±11% for haplo, 30±4% for 10/10 UD and 34±9% for 9/10 UD, p=0.6). Likewise, the 2-y CI of cGvHD (35±12%) of HaploSCT was similar to those of 10/10 UD (36±4%) and 9/10 UD (36±9%), p=0.8. The 2-y CI of NRM was 19±8% after haploSCT, 18±4% after 10/10 UD SCT and 18±6% after 9/10 UD SCT (p=0.9). Relapse incidence was not significantly affected by donor source, with a 2-y CI of 27±9% for haploSCT, 39±5% for 10/10 UD SCT and 37±9% for 9/10 UD SCT (p=0.3). After adjustment for centre effect, pts age, time from diagnosis to SCT, conditioning intensity, in-vivo TCD, donor/pts gender and CMV serostatus, the multivariable model showed that haploSCT recipients didn't experience worse outcomes compared to 10/10 and 9/10 UD. Indeed, compared to haploSCT (reference) the hazard ratio (HR) for LFS was 1.2 for 10/10 UD (p=0.3) and 1.2 for 9/10 UD (p=0.4). The hazards for OS in 10/10 and 9/10 UD did not differ from haplo-SCT (1.3, p 0.3 and 1.2, p 0.4, respectively). Moreover, compared to haplo, SCT from 10/10 and 9/10 UD was not associated with lower hazards for relapse (HR: 1.4, p=0.2 and 1.4, p=0.3, respectively), NRM (HR: 1, p=0.9 and 1, p=0.9, respectively), grade≥2 aGvHD (HR: 1.2, p=0.6 and 1.4, p=0.3, respectively) and cGvHD (HR: 1.2, p=0.5 and 1.3, p=0.4, respectively). The only factor associated with worse LFS and OS was pts age (for each 10-year interval: HR 1.1, p=0.02 and 1.2, p=0.001, respectively). Conclusions: In the present series of poorAML pts transplanted in CR1, haploSCT recipients experienced comparable outcomes with respect to 10/10 and 9/10 HLA-matched UDs. This suggests that the immunotherapeutic effect of allogeneic SCT is exerted similarly across these different donor sources in this peculiar population. Therefore, in the absence of a MRD, pts with poor risk cytogenetics who have a very high risk of relapse could be allocated to haploSCT in their first remission, especially in the context of the recent improvements, which fostered an abatement of GvHD and NRM rates, historically the main detrimental factors for Haploidentical transplants. Disclosures Ciceri: 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.

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