Unrelated Donor Hematopoietic Stem Cell Research Articles

Pilot study using post-transplant cyclophosphamide (PTCy), tacrolimus and mycophenolate GVHD prophylaxis for older patients receiving 10/10 HLA-matched unrelated donor hematopoietic stem cell transplantation.

Allogeneic SCT for older patients remains challenging at least in part due to graft-versus-host disease (GVHD) and higher non-relapse mortality (NRM). We conducted a prospective pilot study primarily for older patients undergoing matched unrelated donor (MUD) SCT using a reduced-intensity (RIC) melphalan-based conditioning and post-transplant cyclophosphamide (PTCy)-based GVHD prophylaxis with tacrolimus and mycophenolate mofetil. Twenty-two patients (median age 64, IQR 58, 66) underwent RIC MUD SCT for high-risk hematological malignancies including AML/MDS (73%), CML/MPD (18%), and other (10%). Two (9%) patients had early death; the rest (100%) engrafted. After a median follow-up of 17 months, 11 patients were alive and disease-free with an estimated 2-year progression-free (PFS) and overall (OS) survival of 48%. The cumulative incidences of grades 2-4 and 3-4 acute GVHD (aGVHD) at day + 100 and 2-years were 32 and 4%, and 59 and 24%, respectively. No cases of chronic GVHD (cGVHD) were noted. However, late acute GVHD was observed in 6 (27%) patients. In conclusion, RIC MUD SCT with melphalan-based conditioning and PTCy-based GVHD-based prophylaxis for older patients appears effective in controlling relapse. While cGVHD was not seen and early aGVHD appears controllable, a significant proportion developed late aGVHD responsible for higher NRM seen in these patients.

CD3+/CD19+ Depleted Matched and Mismatched Unrelated Donor Hematopoietic Stem Cell Transplant with Targeted T Cell Addback Is Associated with Excellent Outcomes in Pediatric Patients with Nonmalignant Hematologic Disorders

Unrelated donor hematopoietic stem cell transplantation (HSCT) is increasingly being used to cure nonmalignant hematologic diseases (NMHD) in patients who lack HLA matched related donors. Both graft rejection and graft-versus-host disease (GVHD) remain major barriers to safe and effective transplant for these patients requiring unrelated donors. Partial T cell depletion combined with peripheral stem cell transplantation (pTCD-PSCT) has the potential advantages of providing a high stem cell dose to facilitate rapid engraftment, maintaining cells that may facilitate engraftment, and decreasing GVHD risk compared with T cell–replete HSCT. Here, we report a single-institution, retrospective experience of unrelated donor pTCD-PSCT for pediatric patients with NMHD. From 2014 to 2017, 12 pediatric patients with transfusion-dependent NMHD underwent matched unrelated donor (MUD) or mismatched unrelated donor (MMUD) pTCD HSCT in our center using disease-specific conditioning. Donor PSCs underwent CD3+ T cell and CD19+ B cell depletion using CliniMACS, followed by a targeted addback of 1 × 105 CD3+ T cells/kg to the graft before infusion. All 12 patients demonstrated rapid trilinear engraftment. At a median follow-up of 740days (range, 279 to 1466), all patients were alive with over 92% total peripheral blood donor chimerism and without transfusion dependence or recurrence of their underlying hematologic disease. Immune reconstitution was rapid and comparable with T cell–replete HSCT. No patients developed severe acute GVHD (grades III to IV) or chronic extensive GVHD, and all patients had discontinued systemic immune suppression. Viral reactivations were common, but no patient developed symptoms of life-threatening infectious disease. Our data indicate that MUD and MMUD pTCD-PSCTs are safe and effective approaches that enable rapid engraftment and immune reconstitution, prevent severe GVHD, and expand availability of HSCT to any patients with NMHD who have closely MUDs.

P058 The importance of complete HLA-DQB1 sequences when typing beyond exon 2

Aim This study examined the variation observed when typing exons 2 + 3 of HLA-DQB1 using reverse sequence specific oligonucleotides (rSSO) as compared to typing exon 2 alone in volunteers from an unrelated hematopoietic stem cell donor program. New alleles and those with incomplete sequences were characterized with next generation sequencing (NGS) to update the IPD-IMGT/HLA database. Methods Samples were typed for HLA-DQB1 using One Lambda’s SSO LabType with additional phasing probes for exon 2 ( ∼ 50,000 donors) or for exons 2 + 3 ( ∼ 15,000). Full-length HLA-DQB1 sequences (40) were obtained using an Illumina platform and in-house protocol. Results Overall, 38 incomplete DQB1 alleles were identified and sequenced with NGS, including 6 that could only be detected by rSSO with exon 3 probes. The majority of these alleles appear only 1–2 times in the sample set and were not listed as common or well-documented in Mack et al. 2013. The addition of exon 3 in rSSO typing complicated analysis since many alleles lack sequence data for exon 3, and the software assumes no probe binding if there is no known sequence. An example is DQB1*06:08 ( ∼ 10), which binds to one of the exon 3 probes and therefore is not assigned (i.e., false positive). Two alleles showed discrepant results between rSSO and NGS due to novel sequences. The full-length sequences obtained for all alleles sequenced demonstrate high conservation of the regions outside of exon 2. Conclusions There are advantages and disadvantages from screening exons 2 + 3 of HLA-DQB1. It elucidates greater variation not identified from screening exon 2 alone but has a more complicated analysis due to incomplete DNA sequences. Updating the IPD-IMGT/HLA database is critical for improved accuracy. C. Masaberg: 7. Other (Identify); Company/Organization; Intellectual property typing workflow, One Lambda licensing. C.K. Hurley: 7. Other (Identify); Company/Organization; Intellectual property typing workflow, One Lambda licensing.

Motives for joining an unrelated HSC donor registry: description, categorization, and association with donor availability.

A challenge for registries of unrelated hematopoietic stem cell (HSC) donors is to recruit and retain sufficient donors for patients needing transplants. Many registered HSC donors opt-out when called as a potential match for a patient. Anecdotal evidence suggests that motives for joining a registry may be linked to the donation decision. The primary goals of this investigation were to describe the range of motives for joining a registry and to examine donor availability by motive type. A diverse sample of 357 potential HSC donors from the Anthony Nolan registry in the UK was asked about their motives for joining and their decision to continue or opt-out after matching a patient was recorded. Motives for joining (N = 557) were first coded and categorized into 17 specific motive types and then arranged along a spectrum from internal to external. Internal values-based motives were most prevalent and availability was highest among potential donors expressing these motives (92%) and lowest among those expressing external motives (pressure, incentives; 0%). Although further research is needed to confirm these findings, they suggest that registries should assess donors' motives for joining at recruitment in order to conduct follow-up to ensure commitment among those potential members expressing external motives.

Chromosomal Aberrations and Survival after Unrelated Donor Hematopoietic Stem Cell Transplant in Patients with Fanconi Anemia

Studies of chromosomal aberrations in blood or bone marrow of patients with Fanconi anemia (FA) have focused on their associations with leukemic transformation. The role of such abnormalities on outcomes after hematopoietic cell transplantation (HCT) is unclear. We used genome-wide single nucleotide polymorphism arrays to identify chromosomal aberrations in pre-HCT blood samples from 73 patients with FA who received unrelated donor HCT for severe aplastic anemia between 1991 and 2007. Outcome data and blood samples were available through the Center for International Blood and Marrow Transplant Research. For survival analyses, we used the Kaplan-Meier estimator to calculate the survival probabilities and the exact log-rank test to compare the survival differences across groups. Chromosomal aberrations were detected in 16 (22%) patients; most frequent were clonal copy loss in chromosome 7 (9.6%), clonal copy gains in the long arm (q) of chromosome 1 (chr1q+) (8.2%), and clonal or complete copy gains in the q arm of chromosome 3 (chr3q+) (8.2%). Seven (9.6%) patients had alterations in 3 or more chromosomes. Poor post-HCT overall survival (OS) was noted in patients with chr3q+ (P = .04), or those with abnormalities in ≥3 chromosomes (P = .03). The 1-year OS was 0% versus 45% in patients with either alteration versus its absence. No statistically significant differences in OS were noted in patients carrying deletions in chr7 (1-year OS = 29% versus 42%; log-rank P = .74). The study is limited by the small sample size. A larger, prospective study is warranted to validate our findings in light of recent improvement in transplant modalities and outcomes.

Continuous Mononuclear Cell Collection (cMNC) protocol impact on hematopoietic stem cell collections in donors with negative collection predictors

BackgroundRecently, novel protocol utilizing Continuous Mononuclear Cell Collection (cMNC) have been introduced for leukapheresis. We compared the efficacy of cMNC with an older protocol – mononuclear cell collection (MNC) for CD34+ cell collection in unrelated donors with negative stem cell collection predictors. Material and methodsRetrospective data from a series of 258 consecutive unrelated hematopoietic stem cell donors was included in this single-center study (80 donors collected with cMNC and 178 with MNC). The donors with poor predictors for collection such as low number of circulating CD34+ cells and/or weight disproportion were assigned to the cMNC arm. ResultsThe cMNC protocol yielded a higher number of CD34 + cells per donor body weight (7.63 × 106/kg vs 6.82 × 106/kg, p = 0.027). One apheresis was sufficient for collection of target cell number in 89% individuals from both groups despite negative predictors in the cMNC group. In donors with CD34 + cell count <100/μL and a body weight disproportion between donor and recipient one apheresis was sufficient in 83% of donors in cMNC group and in 58% in MNC group (p = 0.0345) with collection efficiency CE2% values of 61% for cMNC and 62% for MNC (p = 0.77). ConclusioncMNC protocol is more efficient in donors with low pre-apheresis CD34+ cell count and weight disproportion between donor and recipient. This suggests that the use of cMNC in unrelated donors could possibly further improve the results of HSC collections.

Anti-CD36 Mediated Platelet Transfusion Refractoriness and Related Cases After Stem Cell Transplantation

To analyse the cases of platelet transfusion refractoriness after received HLA-matched unrelated donor hematopoietic stem cell transplantation, to analyze and identify the phenotype and genotype of CD36 in both the patient and stem cell donor, as well as the characteristic of antibody induced platelet transfusion refractoriness, and to analyse the efficacy of matched CD36-deficiency platelets transfusions. The CD36 expression on platelet and monocyte was analyzed by flow cytometry (FCM) in both patient and donor. Polymerase chain reaction sequence-based typing (PCR-SBT) was used to analyze the exons sequence of CD36 and HPA. Fast monoclonal antibody-specific immobilization of platelet antigen (F-MAIPA) and FCM were used to identify platelet antibodies in the patient. Short tandem repeat polymerase chain reaction (STR-PCR) was applied to monitor engraftment evidence. The platelet level was monitored. CD36- deficiency donor's platelets were selected from CD36- deficiency donor blood bank. The donor was CD36 positive and the patient was typed I CD36 deficiency. The anti-CD36 antibody was identified in patient's serum (after transplantation), while the HLA and HPA-related antibodies were excluded. Sequence analysis of CD36 exon in the patient showed Exon 6 -1G>C(Change in splicing site) homozygote, which was a novel CD36 mutation. STR, HPA and CD36 of the patient (complete chimerism) were conversed to that of donor gene types on day 18 after allo-HSCT. The positive CD36 expression on platelet and monocyte in the patient was observed on day 96 after allo-HSCT. The patient showed the platelet transfusion refractoriness which was significantly improved after platelets transfusions from CD36 deficiency donors. Stem cell transplants resulted in anti-CD36 and caused platelet transfusion refractoriness, that was first reported in China. To ensure the efficacy of platelet transfusion, the CD36-deficiency patient should receive CD36 deficiency platelets for transfusion.

Bone marrow harvest from unrelated donors-up-to-date methodology.

Bone marrow harvesting is one of the essential sources of stem cells for hematopoietic stem cell transplantation. We describe here the current "up-to-date" standard of the bone marrow harvest in unrelated stem cell donors. We analyzed medical data of 187 unrelated hematopoietic stem cell donors who underwent bone marrow harvest without previous peripheral blood stem collection at the center between 2011 and 2015. The methodology of marrow collection includes multiple cells aimed at safety of the procedure, for example, educational movie, modified skin disinfection protocol, cell enumeration during the procedure, reduction of the contamination surfaces, and ongoing monitoring of the quality of work of the doctors. The total nucleated cell count over 2×108 per kg of recipient has been reached in 93.6% of harvests. All of the donors harvested more than 1×108 per kg of the recipient. There were no donors who required transfusions or had serious adverse events during and after the harvest. We describe here the current up-to-date standard of bone marrow harvest, which leads to excellent results in majority of donors without causing significant complications during the donation.

P227 Determination of HLA -A, -B and - DRB1 alleles and HLA-A -B haplotype frequencies in Egyptians based on family study

Knowledge of allele and haplotype frequencies in human populations guides the search for an HLA- matched unrelated hematopoietic stem cell donor. A new algorithm developed by the National Marrow Donor program uses this information to predict the likelihood that a volunteer of a particular ethnicity will carry specific HLA alleles when typed at high resolution. In the present study, we determined the HLA-A,-B and -DRB1 alleles and HLA-A-B haplotype frequencies in Egyptians and compared them to various populations. Specificities of HLA-A, -B and -DRB1 loci were determined in 286 matched related donors of allogeneic hematopoeitic stem cell transplantation (AHSCT). Typing was performed using serologic and low resolution PCR- reverse sequence-specific oligonucleotide (rSSO) techniques. HLA-A-B haplotypes were defined by segregation analysis. The most frequent alleles for HLA class I HLA-A were: HLA-A2 (19.2%), A1 (15.8%), A30 (9.2%) and A24 (8.8%), for HLA-B, B41 (10.9%), B35 (10.2%), B44 (6%) and B50 (5.4%) and for DRB1∗13 (18.7%), ∗04 (15%) ,∗11(14.7%) and ∗03 (13.2%). The most frequent HLA-A-B haplotypes were: A24-B35 (3.8%), A2-B41 (3.4%), A1- B35 (3.4%) and A33-B14 (3.4%). This study report HLA allele and HLA-A-B haplotype patterns in Egyptians. These patterns were close to Jordanians and Lebanese and different from Saudi Arabians, Europeans, Americans and Asians. These data explain the difficulty of finding donors in world registries for Egyptian patients in need of a stem-cell transplant and highlight the need to for planning an Egyptian national unrelated donor registry to meet the demands of these patients.

Epitopic analysis suggests a new conformational DPαβ epitope in a patient searching for an unrelated hematopoietic stem cell donor

The best available unrelated donor (URD) for a patient with acute lymphoblastic leukemia in need of hematopoietic stem cell transplant was HLA 11/12 with a DPB1*04:01 mismatch. Search for donor-specific HLA antibodies (DSA) by solid phase assay with isolated HLA molecules (SAB) on a first panel (manufacturer 1) identified a DSA against DPB1*04:01 (MFI = 3090). Epitope analysis using HLA Fusion and HLAMatchmaker was not conclusive due to an atypical 85GPM epitope pattern, showing positive reactions with DPB1*04:01 (MFI = 3090), DP2 (MFI = 1655), DPB1*04:02 (MFI = 4571), DP23 (MFI = 1549) and DP28 (MFI = 1409, 1324, 1256), but lack of reactivity with DP15 and DP18, which also express 85GPM. The DP α 31 M + β 85GPM + β 96 R configuration, obtained with the HLA Epitopia Map, justified the observed pattern because it is present in the DP4, DP2, DP23 and DP28 heterodimers that reacted positively, but absent in DP15 ( α 31 Q + β 85GPM + β 96 K ) and DP18 ( α 31 Q + β 85GPM + β 96 K and α 31 M + β 85GPM + β 96 K ) whose reactions were negative. To validate this α / β epitope predicted in silico , the serum was tested with an SAB panel which included five distinct DP4 heterodimers (manufacturer 2) composed of DPB1*04:01 combined to different alpha chains. The result showed that only heterodimers with α 31 M + β 85GPM + β 96 R configuration were reactive: DPA1*01:03/DPB1*04:01 (MFI = 3609), DPA1*03:01/DPB1*04:01 (MFI = 3778) and DPA1*04:01/DPB1*04:01 (MFI = 3750). The α 31 Q + β 85GPM + β 96 R heterodimers showed negative reactions (DPA1*02:01/DPB1*04:01, MFI = 298; DPA1*02:02/DPB1*04:01, MFI = 94) (Table). Patient was transplanted with this URD without previous desensitization due to the weak reactivity of this antibody. This DP αβ DSA did not show clinical relevance in the rejection vector, since there was hematological engraftment on day +26 and chimerism with 100% donor cells on day +30. This report suggests the presence of a new conformational DP αβ epitope and shows that HLA Epitopia Map tool contributes to the elucidation of atypical reactivity patterns in SAB solid phase assays.

P068 Impact of anti-HLA antibodies on early complications and outcome in unrelated hematopoietic stem cell transplantation

Aim To evaluate the clinical significance of anti-HLA antibodies (Abs) on early complications and outcome of unrelated donor hematopoietic stem cell transplantation (UD-HSCT). Methods From June 1, 2014 to March 20, 2016, 90 adult patients, who reached 6-month follow-up after their first UD-HSCT or died within this period, were recruited into this study. All donor-patient pairs were 10/10 or 9/10 matched at HLA-A, -B, -C, -DRB1, and -DQB1 loci. Additionally, HLA-DRB3,4,5 and -DPB1 loci were typed. Patients’ sera sample collection was scheduled before the start of conditioning treatment and at 1, 2, 3, and 6 months after UD-HSCT. Anti-HLA Abs were screened and identified by solid-phase immunoassays on the Luminex platform. HLAMatchmaker programs were used to perform structural HLA class I and class II matching at the eplet level. Results Patient’s median age was 56 years (range 19–74) and 47 of 90 patients (52.2%) were men. Seventy-four donor - patient pairs (82.2%) were 10/10 matched. Eighty-nine of 90 patients (98.8%) received peripheral blood stem cell graft. All patients achieved neutrophil engraftment and four patients (4.4%) had secondary graft failure. The overall prevalence of preformed anti-HLA Abs (no donor-specific antibodies were found) was 41.1% and 32 of 37 patients retained anti-HLA Abs after UD-HSCT. The presence of preformed anti-HLA Abs was found to be associated with the development of early grades III and IV acute graft-versus-host disease (aGVHD) post-transplant complications ( p = 0.0446), higher transplant-related mortality ( p = 0.011), and shorter overall survival ( p = 0.021). The preformed anti-HLA Abs did not affect engraftment, incidence of relapse, graft failure, event free survival or development of non-aGVHD complications. Anti-HLA Abs detected after UD-HSCT (retained and de novo) had no impact on development of early complications and outcome of UD-HSCT. Nine patients developed de novo anti-HLA Abs after UD-HSCT. In the only case they were donor-specific and directed against mismatched DQA1*/DQB1* antigens. Conclusions Preformed anti-HLA Abs have impact on development of severe aGVHD, higher transplant related mortality and reduced overall survival after UD-HSCT. Therefore, routine testing for anti-HLA Abs may be considered in pre-transplant work-up of the recipients.

Short-term side effects and attitudes towards second donation: A comparison of related and unrelated haematopoietic stem cell donors.

The Nordic Register of Haematopoietic Stem Cell Donors (NRHSD) has registered related and unrelated donors from 10 transplant centres in Sweden, Norway, Finland and Denmark since 1998. We present a prospective, observational study of 1,957 donors, focusing mainly on the differences between related and unrelated donors. Related donors are reported to have more comorbidities, but similar side effects compared with unrelated donors. Side effects after BM or PBSC donation are generally of short duration and in this study no deaths, myocardial infarctions, splenic ruptures, or thromboembolic events are reported. Interestingly, related donors express more hesitancy towards donating again when asked 1 month after donation.

Biosimilar G-CSF versus filgrastim and lenograstim in healthy unrelated volunteer hematopoietic stem cell donors

The World Marrow Donor Organization recommends original granulocyte-colony stimulating factor (G-CSF) for the mobilization of stem cells in healthy unrelated hematopoietic stem cell donors. We report the comparison of a biosimilar G-CSF (Zarzio) with two original G-CSFs (filgrastim and lenograstim) in mobilization in unrelated donors. We included data of 313 consecutive donors who were mobilized during the period from October 2014 to March 2016 at the Medical University of Warsaw. The primary endpoints of this study were the efficiency of CD34+ cell mobilization to the circulation and results of the first apheresis. The mean daily dose of G-CSF was 9.1 μg/kg for lenograstim, 9.8 μg/kg for biosimilar filgrastim, and 9.3 μg/kg for filgrastim (p < 0.001). The mean CD34+ cell number per microliter in the blood before the first apheresis was 111 for lenograstim, 119 for biosimilar filgrastim, and 124 for filgrastim (p = 0.354); the mean difference was even less significant when comparing CD34+ number per dose of G-CSF per kilogram (p = 0.787). Target doses of CD34+ cells were reached with one apheresis in 87% donors mobilized with lenograstim and in 93% donors mobilized with original and biosimilar filgrastim (p = 0.005). The mobilized apheresis outcomes (mean number of CD34+ cells/kg of donor collected during the first apheresis) was similar with lenograstim, biosimilar filgrastim, and filgrastim: 6.2 × 106, 7.6 × 106, and 7.3 × 106, respectively, p = 0.06. There was no mobilization failure in any of the donors. Biosimilar G-CSF is as effective in the mobilization of hematopoietic stem cells in unrelated donors as original G-CSFs. Small and clinically irrelevant differences seen in the study can be attributed to differences in G-CSF dose and collection-related factors. Active safety surveillance concurrent to clinical use and reporting to donor outcome registry (e.g., EBMT donor outcome registry or WMDA SEAR/SPEAR) might help to evaluate the possible short- and long-term complications of biosimilar G-CSF.

Hapl-o-Mat: open-source software for HLA haplotype frequency estimation from ambiguous and heterogeneous data

BackgroundKnowledge of HLA haplotypes is helpful in many settings as disease association studies, population genetics, or hematopoietic stem cell transplantation. Regarding the recruitment of unrelated hematopoietic stem cell donors, HLA haplotype frequencies of specific populations are used to optimize both donor searches for individual patients and strategic donor registry planning. However, the estimation of haplotype frequencies from HLA genotyping data is challenged by the large amount of genotype data, the complex HLA nomenclature, and the heterogeneous and ambiguous nature of typing records.ResultsTo meet these challenges, we have developed the open-source software Hapl-o-Mat. It estimates haplotype frequencies from population data including an arbitrary number of loci using an expectation-maximization algorithm. Its key features are the processing of different HLA typing resolutions within a given population sample and the handling of ambiguities recorded via multiple allele codes or genotype list strings. Implemented in C++, Hapl-o-Mat facilitates efficient haplotype frequency estimation from large amounts of genotype data. We demonstrate its accuracy and performance on the basis of artificial and real genotype data.ConclusionsHapl-o-Mat is a versatile and efficient software for HLA haplotype frequency estimation. Its capability of processing various forms of HLA genotype data allows for a straightforward haplotype frequency estimation from typing records usually found in stem cell donor registries.

The novel HLA-DRB1*15:140 allele discovered in a Taiwanese unrelated hematopoietic stem cell donor.

One nucleotide substitution at residue 91 of HLA-DRB1*15:02:01:01 results in a new allele, HLA-DRB1*15:140.

200 - Analysis of Predicted Indirectly Recognizable HLA Epitopes (PIRCHE) in Mismatched Unrelated Donor Hematopoietic Stem Cell Transplants (HCT): A Center for International Blood and Marrow Transplant Research (CIBMTR) Cohort Study

200 - Analysis of Predicted Indirectly Recognizable HLA Epitopes (PIRCHE) in Mismatched Unrelated Donor Hematopoietic Stem Cell Transplants (HCT): A Center for International Blood and Marrow Transplant Research (CIBMTR) Cohort Study

135 - Outcomes of Unrelated Donor Hematopoietic Stem Cell Transplantation for Pediatric Patients: The First Report From Iran

135 - Outcomes of Unrelated Donor Hematopoietic Stem Cell Transplantation for Pediatric Patients: The First Report From Iran

85 - Impact of ABO-Mismatching Following HLA- Mismatched Unrelated Donor Hematopoietic Stem Cell Transplantation for AML—a Report From the ALWP of the EBMT

85 - Impact of ABO-Mismatching Following HLA- Mismatched Unrelated Donor Hematopoietic Stem Cell Transplantation for AML—a Report From the ALWP of the EBMT

Does MHC Class I Chain-Related Gene A Matter?

In this issue of Biology of Blood and Marrow Transplantation, Askar et al. evaluate the association of MHC class I chain–related gene A (MICA) polymorphisms with the development of graft-versus host-disease (GVHD) after unrelated donor hematopoietic stem cell transplantation (HCT) [1]. Prior reports have provided conflicting results, leaving the effect of MICA donor-recipient mismatch in HCT unanswered.

Matched unrelated donor hematopoietic stem cell transplantation - our results

Introduction. Allogeneic stem-cell transplantation is only potentially curative therapy for variety of hematology malignancies, such as acute and chronic leukemia, myelodisplastic syndrome and aplastic anemia, but also promising treatment option for other disorders. If we know that only 25% of patients have an human leukocyte antigen identical sibling donor, it is obvious that matched unrelated donor hematopoietic stem cell transplantation is an alternative for the rest of the patients. Material and Methods. Since 2013, matched unrelated donor hematopoietic stem cell transplantation has been performed routinely in the Military Medical Academy. Results. We hereby present the outcome after 77 procedures in 75 patients. Considering primary diseases, 35 patients had acute myeloid leukemia, 25 patients had acute lymphoid leukemia, 5 patients had chronic myeloid leukemia, 9 patients had myelodisplastic syndrome and we performed the transplant on 1 patient with chronic lymphocyte leukemia, 1 patient with aplastic anemia and 1 patient with T lymphoblastic lymphoma. Conclusion. It is difficult to make clear conclusions based on this heterogeneous group of patients, but it seems that these results are encouraging. Future research will be performed to evaluate matched unrelated donor and identical sibling hematopoietic stem cell transplantation in the homogenous groups with respect to primary diseases.