Introduction. Syngeneic hematopoietic stem cell transplantation is a type of allogeneic stem cell transplantation when the donor of stem cells is a genetically identical (monozygotic) twin of the recipient. After this type of transplantation, there is no immunological conflict as the graft versus host disease, but at the same time, there is no positive effect of the graft-versus-leukemia effect. Aim: to assess the overall survival, event-free survival, probability of relapse, and transplant-related mortality rates associated with syngeneic stem cell transplantation. Patients and methods. In the National Research Center for Hematology from January 1988 to December 2018 we performed 654 allo-HSCT: 17 (2.5%) of them from a syngeneic donor. We performed a «paired analysis» with patients after allo-HSCT from a HLA-identical sibling donor. We included patients after allo-HSCT from an HLA-identical related donor (n = 28) in Group 1 and patients after syngeneic stem cell transplantation in group 2 (n = 14). Patients with aplastic anemia (n = 3) were excluded from the «paired analysis». Results. Patients after syngeneic stem cell transplantation did not develop a graft-versus-host disease. The relapse developed in 50% of cases (n = 7). Five patients (35.7%) died: 4 of them due to the relapse of the disease, and 1 - due to the graft failure. The relapse probability in patients after syngeneic HSCT was higher and amounted to 18.4% versus 54.2% (p = 0.047) for allo-HSCT from HLA-identical sibling donor and a syngeneic donor, respectively. Overall and event-free survival in patients after syngeneic HSCT is comparable to those in patients after allo-HSCT from an HLA-identical sibling donor. Conclusion. Syngeneic hematopoietic stem cell transplantation is justified in the absence of another related or unrelated donor of hematopoietic stem cells. The use of myeloablative conditioning regimens, peripheral blood stem cells as a source of stem cells, or high doses of nucleated cells/kg in the case of using bone marrow will improve post-transplant parameters in patients after syngeneic hematopoietic stem cell transplantation.

Background. Bloodstream infections (BSI) are common after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The objective of study was to analyze pre- and post-engraftment BSI.Materials and methods. From January 2018 till May 2021242 patients after first allo-HSCT were enrolled in the study. Median age was 35 (17–65) years. The majority of transplants were done for acute leukemias (71.9 %) in remission (91.7 %) with reduced-intensity conditioning regimens (71.5 %) and peripheral blood stem cells (74.4 %) as a graft source.Results. Of 242 patients 95 (39.2 %) developed BSI: 79 (83.2 %) developed 1 BSI episode, 16 (16.8 %) – 2 or more. Overall 113 BSI episodes were registered: 94 (82.7 %) were caused by single microorganism, 19 (17.3 %) were polymicrobial. Probability of pre-engraftment BSI was 31.0 %, post-engraftment – 11.8 %. In total 134 microorganisms were identified: 61.2 % – gram-negative and 38.8 % – gram-positive bacteria. Gram-negative BSI rate was significantly higher during post-engraftment compared to pre-engraftment phase (57.7 % vs. 70.3 %; р = 0.008). Major risk factor for pre-engraftment BSI was mismatched unrelated allo-HSCTs (hazard ratio (HR) 2.55; 95 % confidence interval (CI) 1.32–4.91; р = 0.03), for post-engraftment BSI – secondary poor graft function (HR 21.70; 95 % CI 7.95–59.24; р <0.0001) and graft failure (HR 21.55; 95 % CI 6.27–74.08; р <0.0001), and gut graft-versus-host disease (HR 12.90; 95 % CI 5.77–28.80; р <0.0001). Thirty-day survival after each BSI episode was 90.3 % and was significantly lower in patients with post-engraftment BSI compared to pre-engraftment (71.9 % vs. 97.5 %; р <0.0001).Conclusion. Gram-negative bacteria prevailed in the etiology of BSI. The main risk factors for pre-engraftment BSI was allo-HSCT from mismatched unrelated donors, for post-engraftment BSI – secondary poor graft function and graft failure. Post-engraftment BSI is associated with worse prognosis.

Introduction. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a standard treatment for many patients with hematological malignancies. Over the past 20 years, an increase in transplantation activity has been noted throughout the world. About 50 % of all allo-HSCT are transplanted from unrelated donors. Aim: to present the dynamics and stages of the development of unrelated donation using the example of one transplant center. Materials and methods. This study analyzed Allo-HSCT performed from 2009 to March 2019 at the National Research Center for Hematology (NRCH). The work of the unrelated donor recruiting group and the tissue typing laboratory was analyzed for this period. 107 patient requests for unrelated donor search were dissected to identify search failures. The parameters of 206 unrelated donors were estimated depending on the register (Russian Federation/foreign). Results. The number of allo-HSCTs did not exceed more than 20 per year, in 2009–2011. Since 2012, the number of alloHSCT signifi cantly increased when the possibility for searching for unrelated donors abroad as well as in the Russian Federation (RF) databases appeared. During this time an increase by more than 50 % was noted in the number of allo-HSCTs. Allo-HSCs from unrelated donors of the Russian Federation make up 30–40 % of all unrelated allo-HSCs. 16 % of potential donors of hematopoietic stem cells included in the NRCH registry are donors of the human blood components. Despite the increasing number of unrelated donors in international and RF databases, 12 % of patients did not fi nd a compatible donor in any of the registers, due to a rare combination of HLA genes. It was revealed that among donors from the RF from whom alloHSCT was performed, there was not a signifi cant prevalence of men, compared to the foreign registry, 50.7 % and 66.7 %, respectively, despite the preference of donor-male by doctors. The 5-year overall survival in patients with acute leukemia in the fi rst complete remission, depending on the performance of allo-HSCT from a donor from the RF or foreign registers, are comparable, 40 % and 39.5 %, respectively. Conclusion. The number of allo-HSCT has increased 5 times over the past 10 years largely due to the development of unrelated donation: 30–40 % of allo-HSC transplants received from unrelated donors were performed from donors from the United database of the Russian Federation. The 5-year overall survival of these patients is comparable with the results of the overall survival patients who received transplants from donors from foreign registers.

Aim. To assess the rehospitalization data of patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT), to determine possible risk factors for rehospitalization, and to work out a strategy of post-transplantation follow-up for this category of patients. Materials & Methods. From 2009 to 2019 at the National Research Center for Hematology 418 patients received allo-HSCT. The final analysis included 374 patients who were discharged from hospital after allo-HSCT. The reasons for rehospitalizations of patients with allo-HSCT within 30 days after their hospital discharge were subjected to analysis. Independent risk factors for rehospitalizations were identified by the Cox model. Risk density was visually estimated within 365 days after hospital discharge with the purpose of working out the optimal strategy of post-transplantation follow-up for this category of patients. Results. The probability of rehospitalization within 30 days after hospital discharge was 30.7 % for all patients with allo-HSCT. The data assessment showed that the majority of rehospitalizations (55.7 %) were associated with infectious complications. Acute graft-versus-host disease (GVHD) during the first hospitalization, i.e. immediately after allo-HSCT during the hospital stay, proved to enhance the probability of rehospitalizations within 30 days after hospital discharge by 1.7 times compared with the patients without acute GVHD. Conclusion. The leading cause of rehospitalizations of patients with allo-HSCT within 30 days after hospital discharge was acute GVHD which occurred before, i.e. during the first hospital stay. The data obtained demonstrate the necessity of close monitoring of a patient’s status within the first 120 days after discharge from the hospital where allo-HSCT was performed.