Haplo Stem Cell Transplantation Research Articles

Alternative donor transplantation for severe aplastic anemia: a comparative study of the SAAWP EBMT

AbstractSelecting the most suitable alternative donor becomes challenging in severe aplastic anemia (SAA) when a matched sibling donor (MSD) is unavailable. We compared outcomes in patients with SAA undergoing stem cell transplantation (SCT) from matched unrelated donors (MUD) (n = 1106), mismatched unrelated donors (MMUD) (n = 340), and haploidentical donors (Haplo) (n = 206) registered in the European Society for Blood and Marrow Transplantation database (2012-2021). For Haplo SCT, only those receiving posttransplant cyclophosphamide for graft-versus-host disease (GVHD) prophylaxis were included. Median age was 20 years, and the median time from diagnosis to transplantation 8.7 months. Compared with MUD, MMUD (hazard ratio [HR], 2.93; 95% confidence interval [CI], 1.52-5.6) and Haplo (HR, 5.15; 95% CI, 2.5-10.58) showed significantly higher risks of primary graft failure. MUD had lower rates of acute GVHD compared with MMUD and Haplo (grade 2-4: 13%, 22%, and 19%, respectively; P < .001; grade 3-4: 5%, 9%, and 7%, respectively; P = .028). The 3-year nonrelapse mortality rate was 14% for MUD, 19% for MMUD, and 27% for Haplo (P < .001), whereas overall survival and GVHD and relapse-free survival (GRFS) rates were 81% and 73% for MUD, 74% and 65% for MMUD, and 63% and 54% for Haplo, respectively (P < .001). In addition to donor type, multivariable analysis identified other factors associated with GRFS such as patient age, performance status, and interval between diagnosis and transplantation. For patients with SAA lacking an MSD, our findings support MUDs as the preferable alternative donor option. However, selecting between an MMUD and Haplo donor remains uncertain and requires further exploration.

Safety and Efficacy of Orca-Q with Haploidentical Donors for the Treatment of Advanced Hematologic Malignancies without the Use of Post-Transplant Cyclophosphamide

Srour, Salhotra, Lowsky and Abedi contributed equally as authors BACKGROUND Allogeneic stem cell transplantation (SCT) can be curative for several high-risk hematologic malignancies, but access was previously limited to patients with a fully matched donor. The introduction of post-transplant cyclophosphamide (PTCy) GvHD prophylaxis has increased the use of haploidentical donors (haplo) for patients who lack an HLA-matched donor. However, clinical outcomes associated with PTCy-based regimens remain challenging due to increased relapse rates (particularly in the setting of reduced intensity conditioning) and the adverse event profile including higher incidence of mucositis, cytokine release syndrome (CRS), delayed engraftment &amp; T cell reconstitution, infections, early cardiotoxicity events and death from organ failure (Dulery 2021, Abboud 2021, Nagler 2022, Hoover 2022, Bolaños-Meade 2023). Additionally, the incidence of chronic GvHD after haplo SCT with PTCy is 24 - 33% at 1 year in various historical cohorts. Orca-Q -an investigational precision engineered cell therapy biologic- represents an alternative strategy which may be administered with single agent prophylaxis and does not require PTCy. The cellular composition of Orca-Q includes enriched CD34+ stem cells, combined with specific T-cell subsets, and is intended to reconstitute the blood and immune systems. METHODS Adult patients with high-risk hematologic malignancies eligible for MAC SCT were enrolled on the haplo donor dose expansion arm of a multicenter phase1 study of Orca-Q (NCT03802695). Haplo was defined as ≥ 4/8 but &amp;lt; 7/8 matched related donor at HLA-A, -B, -C, and -DRB1 typed using DNA-based high-resolution. Patients received MAC conditioning and single agent GVHD prophylaxis with tacrolimus (starting on day -1 and taper day +60). Orca-Q was manufactured centrally at Orca Bio Manufacturing Site in Sacramento, CA from G-CSF mobilized peripheral blood apheresis. RESULTS Orca-Q was successfully manufactured and delivered to all subjects with a vein-to-vein time (time between end of donor apheresis to start of recipient's Orca-T infusion) of &amp;lt; 72 hours. A total of 33 patients (21 AML, 10 ALL, 2 CML) were included. Median age was 43 (range, 21 - 63) years, 73% were male. Median follow-up was 375 (range, 73 - 1384) days. Sixteen patients received TBI-based MAC; 17 received busulfan-based MAC (Table). All patients engrafted with median time of 12.0 (range, 8 - 25) and 15.5 (range, 8 - 79) days for neutrophil and platelet engraftment, respectively. Two patients had secondary graft failure. Two patients had Grade 1 CRS; 1 patient had Grade 2 CRS. Grade 2+ aGvHD through Day 180+ occurred in 15% of patients. Grade 3-4 acute GvHD (aGvHD) was rare with only 1 event of grade 3 aGvHD and no grade 4 aGvHD. No patients had moderate-to-severe cGvHD. Estimated incidence of CTCAE grade 2 and &amp;gt; grade 3 infections were 9% and 15% at 1 year, respectively. 5 patients died (2 from relapsed disease) during the study period. NRM was 9% at 1 year. The 1-year relapse-free survival, GvHD-and-relapse free survival (Figure), and overall survival at 1 year was 82%. CONCLUSIONS Our findings reveal promising safety and efficacy outcomes using Orca-Q cell therapy for haplo-SCT despite the use of MAC with only single-agent tacrolimus, and without PTCy. With median follow-up of approximately 1 year, no patients experienced moderate or severe cGvHD, the low AE profile in the haplo setting remains favorable, and 1 year GvHD-free, relapse-free survival of 83% is very encouraging. This phase 1 study continues to enroll patients across the US. REFERENCES Abboud R, Wan F, Mariotti J, et al. Bone Marrow Transplant. 2021;56(11):2763-2770. Bolaños-Meade GM, Hamadani M, Wu J. N Engl J Med. 2023; 388(25):2338-2348. Duléry R, Mohty R, Labopin M, et al. JACC CardioOncol. 2021; 3(2):250-259. Hoover A, O'Leary D, Cao Q, et al. Blood. 2022; 140 (Supplement 1):282-283 Nagler A, Tsirigotis P. Bone Marrow Transplant. 2022; 57(11):1640-1641.

The Role of Donor Selection for a Second Allogeneic Stem Cell Transplantation in Patients with AML Relapsing after a First Transplant; A Study on Behalf of the Acute Leukemia Working Party of EBMT

Introduction Recurrent disease is the major cause of treatment failure after allogeneic stem cell transplantation (SCT) in patients with AML. Second SCT (SCT2) is a valid treatment option in this setting but outcome is relatively poor. Haplo-identical (haplo) SCT is increasingly used over the last decade due to the introduction of non T-depleted methods. Prior studies have shown similar outcome when using the same or different HLA-matched donor for SCT2. However, there is relatively limited data on the use of haplo-donors in this setting. Methods and Results The study included 556 patients with AML relapsing after a first allogeneic SCT (SCT1) given in CR1 from sibling (sib, n=294) or unrelated donor (UD, n=262) and given SCT2 during the years 2006-2016. The median age at SCT2 was 46 years (20-73). 247 patients were in CR2 (45%) and 309 had active leukemia (55%) at SCT2. The conditioning regimen for SCT1 was myeloablative (MAC, 66%) or reduced-intensity (RIC, 34%), and 41% and 59%, respectively for SCT2. Patients were divided into 3 groups based on the donor selected for SCT2; 1) same donor (n=163, sib/sib-112, UD/UD-51), 2) different matched donor (n=305, sib/different sib-44, sib/UD-93, UD/ different UD- 168), 3) haplo-donor (n=88, sib/haplo-45, UD/haplo-43). All haploSCT were non T-depleted. The 2-year leukemia-free survival (LFS) after SCT2 was 23.5%, 23.7% and 21.8%, respectively (unadjusted P=0.30). Multivariate analysis showed no effect of second donor type on subsequent relapse, hazard ratio (HR) 0.96 (P=0.83) and 1.20 (P=0.47) for different donor and haplo-donor compared to same donor, respectively. UD in SCT1, CR2 at SCT2 and chronic GVHD after SCT1 were associated with reduced relapse risk after SCT2, HR 0.70 (P=0.02), 0.60 (P=0.001) and 0.66 (P=0.03), respectively. Second donor type did predict for non-relapse mortality (NRM) after SCT2; HR 1.26 (P=0.41) and 2.18 (P=0.02) for different donor and haplo-donor compared to same donor, respectively. Advanced age and MAC in SCT1 also predicted for NRM, HR 1.40 (P Conclusions Second SCT with the same donor or different matched donor is associated with similar outcomes in patients with relapsed AML after a first SCT. However, SCT2 with a haplo-donor is associated with higher NRM and lower LFS, mostly in patients given MAC in SCT1. Second haplo donor does not provide better GVL effect in this setting.

The Role of Donor Selection for a Second Allogeneic Stem Cell Transplantation in Patients with AML Relapsing after a First Transplant; A Study on Behalf of the Acute Leukemia Working Party of EBMT

Introduction. Recurrent disease is the major cause of treatment failure after allogeneic stem cell transplantation (SCT) in patients with AML. Second SCT (SCT2) is a valid treatment option in this setting but outcome is relatively poor. Haplo-identical (haplo) SCT is increasingly used over the last decade due to the introduction of non T-depleted methods. Prior studies have shown similar outcome when using the same or different HLA-matched donor for SCT2. However, there is relatively limited data on the use of haplo-donors.Methods and Results. The study included 556 patients with AML relapsing after a first allogeneic SCT (SCT1) given in CR1 from an HLA-matched sibling (sib, n= 294) or a matched unrelated donor (MUD, n=262) and given SCT2 during the years 2006-2016. The median age at SCT2 was 46 years (20-73). 247 patients were in CR2 (44%) and 309 had active leukemia (55%) at the time of SCT2. The conditioning regimen was myeloablative (MAC, 66%) or reduced-intensity (RIC, 34%) for SCT1, and 41% and 59%, respectively for SCT2. 19% of all patients had acute GVHD grade II-IV and 20% had chronic GVHD after SCT1 and before relapse. Patients were divided into 3 groups based on the donor selected for SCT2; 1) same donor (n=163, sib/sib-112, MUD/MUD-51), 2) different HLA-matched donor (n=305, sib/different sib-44, sib/MUD-93, MUD/ different MUD- 168), 3) haplo-donor (n=88, sib/haplo-45, MUD/haplo-43). All haploSCT were non T-depleted. There were some differences between the 3 groups in the timing of relapse and SCT2. The median time from SCT1 to relapse was similar; 10.6, 12.5 and 9.3 months, respectively (P=0.14). However, the median time from relapse to SCT2 was shorter for the same donor group; 2.8, 3.7 and 3.5 months, respectively (P<0.001) and the median time between SCT1 and SCT2 was longer for the different donor group; 14.3, 17.5 and 13.8 months, respectively (P=0.03). There were no difference between the groups in patient age, gender, disease status at SCT2 or conditioning regimen intensity for SCT1 or SCT2. The 2-year leukemia-free survival (LFS) after SCT2 was 23.5%, 23.7% and 21.8%, respectively (unadjusted P=0.30). Multivariate analysis of factors predicting relapse after SCT2 showed no effect of the second donor type, hazard ratio (HR) 0.96 (P=0.83) and 1.20 (P=0.47) for different matched donor and haplo-donor compared to the same donor, respectively. MUD donor in SCT1, CR2 compared to active disease and chronic GVHD after SCT1 were associated with reduced relapse risk after SCT2, HR 0.70 (P=0.02), 0.60 (P=0.001) and 0.66 (P=0.03), respectively. Age, gender, conditioning regimen used for SCT1 or SCT2 and time to first relapse or to SCT2 did not predict relapse rate after SCT2. The second donor type did predict for non-relapse mortality (NRM) after SCT2; HR 1.26 (P=0.41) and 2.18 (P=0.02) for different matched donor and haplo-donor compared to same donor, respectively. Advanced age and MAC in SCT1 also predicted for NRM, HR 1.40 (P<0.001) and 0.61 (P=0.04), respectively. The second donor also predicted for LFS after SCT2; HR 1.05 (P=0.77) and 1.55 (P=0.03), respectively. Advanced age and SCT2 in CR2 also predicted for LFS; HR 1.11 (P=0.06) and 0.66 (P=0.002), respectively. In all, there were no differences between same or different matched donors in SCT2 outcomes, but haploSCT2 was associated with higher NRM and lower LFS. Significant interaction was detected between second donor type and conditioning for SCT1. The inferior outcome after SCT2 with a haplo-donor was limited to patients given MAC in SCT1. In this setting it was associated with higher relapse and NRM rates and lower LFS, HR 1.86 (P=0.05), 3.40 (P=0.005) and 2.25 (P=0.001), respectively. However, there was no difference in any of these outcomes in patients given RIC in SCT1. Unadjusted analysis showed that in patients with no chronic GVHD after SCT1, haploSCT2 was associated with lower LFS, due to higher NRM. However, LFS was similar in patients with prior chronic GVHD. Multivariate analysis was not feasible due to low patient numbers.Conclusions. Second SCT with the same donor or different matched donor is associated with similar outcomes in patients with relapsed AML after a first SCT. However, SCT2 with a haplo-donor is associated with higher NRM and lower LFS, mostly in patients given MAC in SCT1. Prior chronic GVHD after SCT1 is associated with lower relapse rate after SCT2. The role of prior chronic GVHD in donor selection should be further investigated. DisclosuresFinke:Medac: Consultancy, Honoraria, Other: travel grants, Research Funding; Neovii: Consultancy, Honoraria, Other: travel grants, Research Funding; Novartis: Consultancy, Honoraria, Other: travel grants, Research Funding; Riemser: Consultancy, Honoraria, Research Funding. Gramatzki:Affimed: Research Funding. Stelljes:Novartis: Honoraria; Amgen: Honoraria; JAZZ: Honoraria; MSD: Consultancy; Pfizer: Consultancy, Honoraria, Research Funding. Stoelzel:Neovii: Speakers Bureau. Mohty:MaaT Pharma: Consultancy, Honoraria.

The significance of peri-transplantation minimal residual disease assessed by multiparameter flow cytometry on outcomes for adult AML patients receiving haploidentical allografts.

A retrospective study (n = 460) was performed to assess the relationship between minimal residual disease (MRD) and transplant outcomes in a haplo-stem cell transplantation (SCT) setting. Patients from the pre-MRDneg group and the pre-MRDpos group had comparable outcomes. Compared to post-MRDneg patients, post-MRDpos patients had a higher incidence of relapse (100.0% vs. 8.3%, p < 0.001), lower incidences of overall survival (OS) (16.9% vs. 78.2%, p < 0.001) and leukemia-free survival (LFS) (0% vs. 76.5%, p < 0.001), and comparable probability of NRM (13.4% vs. 16.9%, p = 0.560). In a second set of analyses, all adult AML patients undergoing haplo-SCT were classified into the MRDneg/MRDneg group, the MRD decreasing group, and the MRD increasing group according to MRD dynamics by flow cytometry peri-SCT. Compared to the other two groups, patients from the MRD increasing group had higher cumulative incidences of relapse (MRD increasing, 100.0%; MRDneg/MRDneg, 9.6%; MRD decreasing, 19.2%; p < 0.001) and worse probabilities of OS (MRD increasing, 28.5%; MRDneg/MRDneg, 76.3%; MRD decreasing, 76.0%; p < 0.001) and LFS (MRD increasing, 0.0%; MRDneg/MRDneg, 73.9%; MRD decreasing, 74.0%; p < 0.001). The results indicated that haploidentical allografts might have a beneficial anti-leukemia effect in eradicating pretransplantation MRD, and MRD assessment peri-SCT is useful for risk stratification from a practical perspective.

The importance of natural killer cell killer immunoglobulin-like receptor-mismatch in transplant outcomes.

In recent years, the rules of engagement between natural killer (NK) cells and their targets have become better defined with the identification of an array of NK surface molecules, notably the killer immunoglobulin-like (KIR) receptors and their ligands on target cells through which signals of activation or suppression of NK function are mediated. After allogeneic stem cell transplantation (SCT), the opportunity for NK cell activation can occur both in human leucocyte antigen (HLA) matched and HLA mismatched pairs. Although less well explored in HLA identical transplants, many studies confirm the importance of NK KIR mismatching in the graft-versus-leukemia effect in haploidentical (haplo) SCT and this has stimulated recent research to better define the role of NK mismatching on transplant outcome. In this review, we describe recent progress in identifying favorable and unfavorable NK matching in SCT. Recent studies focus less on KIR-HLA mismatching and more on KIR genes as tools to predict alloreactivity via NK licensing and activating KIR. Current results show that transplant outcomes could be improved by judicious selection of favorable donors.

Differences in Natural Killer(NK) Reconstitution Between Unmanipulated Haploidentical and HLA Identical Stem Cell Transplantation and Relationship with Citomegalovirus and Graft Versus Host Disease (GVHD). Experience in One Centre in 22 Patients.

Introduction: It´s well known that NK cells exert an important role in postransplant immune reconstitution. Their maturation process through the contact with recipient´s bone marrow stromal cells is crucial for the development of their functional capacities. Previous studies showed the relevance of NK alloreactivity in relapse prevention and the influence of NK subpopulations and expression of activating receptors on CMV infection control, antitumor effects, and graft versus host disease (GVHD). Unmanipulated Haploidentical (Haplo) transplantation with postrasplant cyclophosphamide (Cy) is an emerging alternative for patients (pts) with no identical sibling donor with encouraging results. We previously reported preliminary data of NK cell reconstitution in 7 pts in Haplo setting. Our aim is to contrast our previous data in 22 pts comparing with conventional HLA-identical (HLAid) Stem Cell Transplantation (SCT) and to analyse the relationship between NK reconstitution and CMV reactivation and GVHD.Methods: 22 pts received an Haplo SCT and 7 pts an HLAid SCT in Gregorio Marañon Hospital between January 2013 and April 2014. Peripheral blood was used in all cases. Conditioning regimen comprised fludarabine (Flu), Cy and busulfan (Bux) for Haplo and Flu/Bux or Flu/Melphalan for HLAid SCT. Prophylaxis for GVHD consisted of high dose Cy on +3, +4, cyclosporine (CsA) A and mycophenolatemofetil for Haplo and CsA/Methotrexate for HLAid. Table1 show patients characteristics. For analysis of NK reconstitution and receptor expression multi-colour flow cytometry on FC500 and Navios Beckman Coulter® was used. Total NK cells, CD56 intensity and expression of NKG2A, NKp30, Nkp46 and NKG2D was studied at +15, +30, +60, and +90. For comparison between the two groups Mann–Whitney U-test was used.Results: Median NK cells/mm3 on +15 and +30 were significantly lower on Haplo than HLAid group ( 0 (0-5.5) and 28.5 (12.2-96.5) vs 69.5 (55-134) and 276 (151-422); p<0.05), being similar on + 60 and +90 (86 (49.5-158) and 147 (85-204.5) for Haplo vs 105 (39.2-162.5) and 117 (82-197) for HLAid; p ns). In Haplo pts NK cells reached normal levels on +60, while only 6/22 (27%) on +30. As previously reported NK high percentages of immature CD56bright (CD56b) cells and high expression of immature receptor NKG2A appears on +30, decreasing on +60 and +90 (CD56b 80% (72.5-88.5), NKG2A 88% (80-94) on +30, 39% (25-49) and 73% (62.2-86.7) on +60, 34% (23-43) and 69% (54.7-77.5) on +90. Compared with HLAid patients, the percentage of NKb cells was significantly higher (p<0.05) on Haplo group on +30, +60 and +90 and expression of NKG2A was also higher on +15, +30 and +60 (p<0.05). Interestingly, expression of activating receptors NKP46 and NKG2D linked to NK maturation are only significantly decreased in Haplo group comparing with HLAid on +15 (p<0.05), with appropriate expression and no differences on +30, +60 and +90. In fact, expression of NKP46 tended to be higher in Haplo on +30 (81% (62.5-90) vs 61% (42-71)), with no statistical significance (p 0.06). NKP30 had a low expression, similar in the 2 groups. In Haplo pts, no differences were found in total NK cell between pts with and without CMV reactivation at any time. Patients with acute GVHD had lower NK cells/mm3 at +30 (21.5 (10.7-35) vs 122 (21.7-260.7) and +60 (75(46-137) vs 156 (51-258); p 0.1), but statistical significance was not reached. Proportion of CD56b and NKG2A expression did not show any difference in pts regarding presence of CMV reactivation or GVHD.Conclusions: After Haplo SCT with postransplant Cy NK cell reconstitution seem to be delayed comparing with HLAid sibling SCT, reaching normal levels at +60. As previously reported, we confirm in our series that NK maturation also show a different pattern. In Haplo setting NK cells remains in an immature phenotype with high proportion of NK CD56b and expression of NKG2A much longer than in HLAid pts. Interestingly activating receptors expression, normally linked to maturation is only lower in Haplo pts in +15, but it is similar in both SCT types by day +30 and later, what should translate in appropriate cytotoxic capacity. In Haplo group, those patients with and without CMV reactivation had similar NK cell reconstitution. Patients with GVHD seem to have an impaired early NK reconstitution, but this fact needs to be contrasted.Acknowledgments: Fundación Mutua Madrileña. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Early Evaluation Of Natural Killer Cell Reconstitution Following Unmanipulated Haploidentical Transplantation Compared With HLA-Identical Sibling Transplantation

BackgroundThe main functions of Natural Killer (NK) cells are early protection against viruses or tumour cells and production of cytokines that regulate immune functions. NK cells are the first lymphoid cells to repopulate the marrow after Stem Cell Transplantation (SCT) and reach normal levels within 1 month after transplant. Acquisition of both, inhibiting and activating receptors on developing NK cells is an important step in their functional maturation. Previous studies showed the beneficial effect of NK alloreactivity in prevention of relapse, especially in the setting of haploidentical SCT. The aim of this study is to compare the reconstitution of the NK cell compartment during the first 3 months after unmanipulated haploidentical peripheral blood SCT (Haplo) and HLA-identical sibling peripheral blood SCT (HLA-id). Patients and Methods11 adult patients received SCT (7 Haplo and 4 HLA-id) at Gregorio Marañón Hospital (Madrid-Spain) from November 2012 to April 2013. Conditioning regimen comprised fludarabine, cyclophosphamide and busulfan for Haplo SCT and fludarabine and busulfan or fludaribine and melphalan for HLA-id SCT. Prophylaxis for acute graft-versus-host disease consisted of high dose cyclophosphamide on days +3 and +4, cyclosporine A and mycophenolate mofetil for Haplo and Cyclosporine A and methotrexate for HLA-id. Patient´s characteristics and transplant outcomes are shown in table 1. We analysed reconstitution patterns and phenotype of NK at day +15, +30, +60, and +90 after transplantation by multi-color flow cytometry on FC500 Beckman Coulter® cytometer using the following anti-human monoclonal antibodies: CD3 FITC, CD56 ECD, CD45 PC7, NKG2A PC7, NKp30 PC5, NKp44 PE, Nkp46 PC5, and NKG2D PE (Beckman Coulter®). For comparison between the two groups Mann–Whitney U-test was used. Results2/7 patients who received Haplo SCT died early in the post-transplantation period (day +50 and +66), and were excluded of the analysis because NK cells were not recovered by those days. NK cells reached normal levels by day +30: median 71 cells/µl (21-1089)) after Haplo; median 213.5 cells/µl (113-499) after HLA-id, and remained at high levels through follow up, with no significant differences between the two groups. Similarly to previous studies, a large percentage of NKbrightcells was observed at day +30 after Haplo (median 89% of NK cells (55-97%)), a percentage that tended to decrease at day +60 (30% (7-38%)) and +90 (35% (10-45%)). Interestingly the percentage of NKbright cells after HLA-id SCT at day +30 (median 14.5% of NK cells (6-30%)) compared with Haplo, was significantly lower (p=0.016). This was accompanied by a significantly lower expression of inhibitory receptor NKG2A after HLA-id SCT than after Haplo: 59.5% (50-62%) versus 92.5% (50-62%) at day +30; 54% (38-61%) versus 86% (70-88%) versus at day +60 (p=0.016). Activating receptors NKp44 and NKp30 showed a low expression after both types of SCT throughout the first 3 months after transplantation. By contrast, activating receptor NKp46 levels were significantly higher at day +30 after Haplo than after HLA-id SCT (93% (87-98%) versus 50% (37-51%)) (p=0.016). Finally, high and similar proportions of activating receptor NKG2D were observed in both types of SCT. Figure 1 illustrates the recovery of the NK cell receptor phenotype for each type of SCT. [Display omitted] [Display omitted] ConclusionsOur data showed an early and fast recovery of NK cells after Haplo and HLA-id SCT. However, phenotypic maturation of NK cells appears to be different for each type of transplant. NK cells generated after Haplo exhibit a more immature phenotype, characterized by a higher proportion of NKbright cells, and a higher expression of NKG2A at day +30. Interestingly expression of NKp46 was significantly higher after Haplo than after HLA-id SCT. Other authors have reported cytotoxic activity of these NK cells with high expression of NKp46, suggesting that cytotoxicity may be preserved in these immature NK cells. NKp30, NKG2D and NKp44 expression is less affected by the type of SCT. AcknowledgmentsThis work has been partially supported by Project “Evaluación de la reconstitución inmune después del trasplante haploidéntico de progenitores hemopoyéticos sin depleción T” from Fundación Mutua Madrileña. Disclosures:No relevant conflicts of interest to declare.