Relapse of acute myeloid leukemia (AML) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains one of the main causes of reduced long-term survival. Modern methods for predicting the risk of AML relapse after allo-HSCT take into account the data on the pre-transplant level of minimal residual disease (MRD) determined by flow cytometry and molecular biological studies of recurrent genetic abnormalities, which are currently widespread in clinical practice. Recent studies of the expression of genes characteristic of leukemic stem cells (LSCs) have shown prognostic significance for children with AML in relation to treatment response and the risk of relapse. The study of LSC persistence in order to predict the risk of recurrence after allo-HSCT in children with AML in addition to standard MRD detection methods may be of great importance. The aim of the work was to evaluate the impact of MRD status, both using classic methods and taking into account the genes characteristic of LSC, on the results of allo-HSCT in children with AML. The study was approved by the Independent Ethics Committee and the Scientific Council of the I.P. Pavlov First Saint Petersburg State Medical University of Ministry of Healthcare of the Russian Federation. To assess MRD using standard diagnostic methods, we analyzed the data of 95 children with AML in their 1 st –2 nd remission (cohort 1). MRD status was negative in 67 (70.6 %) patients; in 28 (29.4 %) children, MRD status was positive according to molecular genetic studies and / or immunophenotyping results. For pre-transplant evaluation of the expression of genes characteristic of LSC, we investigated bone marrow samples of 50 patients (cohort 2) using real-time polymerase chain reaction. The DNMT3B , GPR56 , CD34 , SOCS2 , SPINK2 , FAM30A , and ABL genes were studied by real-time polymerase chain reaction, followed by calculation of the pLSC6 value using the formula: DNMT3b × 0.189 + GPR56 × 0.054 + CD34 × 0.0171 + SOCS2 × 0.141 + SPINK2 × 0.109 + FAM30A × 0.0516. At the time of allo-HSCT, 37 (74 %) children with AML were in their 1 st or 2 nd remission of the disease, 13 (26 %) were out of the 1 st –2 nd remission. With a median follow-up of 5 years in the group of patients with a positive MRD status, determined by standard methods (cohort 1), overall survival (OS) was 67.9 % vs 73.1 % for patients with a negative MRD status (p = 0.83). The cumulative incidence of relapse was 50 % and 22 %, respectively; p = 0.012. When assessing the level of expression of genes characteristic of LSC (cohort 2), a pLSC6 level was above the median in 18/37 (49 %) patients. The results of linear regression showed that the pre-transplant level of expression of genes characteristic of LSC was not associated with the number of blasts/MRD (odds ratio 1.002; 95 % confidence interval 0.979–1.025). One-year OS rates did not differ significantly in children in the 1st–2nd remission of AML, depending on pLSC6 level: 84.2% in patients with low pLSC6 and 72.2 % – with high pLSC6 (p = 0.4), event-free survival in the corresponding groups – 68.4 % and 61.1 %, respectively (p = 0.34). The cumulative incidence of early relapse after allo-HSCT in the group of AML patients with a high pLSC6 score was significantly higher than in children with a low pLSC6 score before allo-HSCT (22 % and 0 %, respectively; p = 0.03). MRD does not have a statistically significant effect on OS. However, MRD positivity before allo-HSCT increases cumulative incidence of relapse. The level of expression of genes characteristic of LSC, determined before allo-HSCT, showed a prognostic significance in relation to the development of early AML relapse after allo-HSCT.

Background. Due to changing views on pathogenesis, risk factors and therapy strategies in prognostically favorable CBF-positive acute myeloid leukemias[1] (AML), the expression monitoring of RUNX1/RUNX1T1 or CBFB/MYH11 fusion genes, as an additional evaluation of treatment outcomes, appears to be insufficient. This indicates the need to improve the monitoring of the CBF+ AML course by means of parallel measurements of BAALC expression levels which roughly correlate with the mass of BAALC-expressing leukemia hematopoietic stem cells (BAALC-e LHSC). Aim. To improve the quality of assessing treatment outcomes with due account for expression levels of RUNX1/RUNX1T1 or CBFB/MYH11 fusion genes and the mass of BAALC-e LHSC and on this basis to pave the way for personalized CBF+ AML treatment. Materials & Methods. This study enrolled 39 adult patients aged 20–81 years (median 32 years) and 8 children aged 2–18 years (median 12 years). Among them there were 20 females and 27 males. AML with inv(16)(p13;q22)/t(16;16) was identified in 19 patients, t(8;21)(q22;q22) was detected in 28 patients. BAALC, WT1, RUNX1/RUNX1T1, CBFB/MYH11 expression levels were measured by quantitative real-time PCR and related to the expression of the ABL1 expert gene. Results. In 23 patients, inv(16) and t(8;21) appeared to be isolated. Additional multidirectional chromosomal changes were observed in 24 patients with inv(16) and in 18 patients with t(8;21). All enrolled patients showed increased BAALC expression. In the course of therapy, it was decreasing to the threshold value in 16/18 (89 %) patients. The evaluation of the mean BAALC expression levels in the pooled groups of children and adults with isolated findings of either inv(16) or t(8;21) showed the decrease of the BAALC-e LHSC mass only in children (p = 0.049). The comparison of the mean WT1 expression levels in the pooled groups of children and adults with isolated and additional chromosomal abnormalities revealed their significant decrease in patients with complicated variants (p = 0.023). Conclusion. The case reports provided in this paper show that the molecular monitoring with serial measurements of fusion genes and BAALC gene expression levels in CBF+ AML patients can lay the basis for further improvement of personalized treatment strategies for these patients. In all likelihood, parallel measurements of the above gene expression levels will allow to establish the framework for decision-making concerning treatment extent and timely HSC transplantation.

Aсute myeloid leukemia (AML) in children aged 0–2 years and aсute lymphoid leukemia (ALL) up to 1 year (i.e., infants) frequently characterize high risk and poor prognosis. Аllogeneic hemopoietic stem cell transplantation (аllo-HCST) is a main curative but toxic option for these patients, and choice of allogeneic donor may be one of the important factor for long-term survival. Aim. To evaluate overall survival (OS), relapse free survival (RFS), transplant related mortality (TRM), "graft versus host" disease free/relapse free survival (GRFS) in infant with acute leukemia underwent allo-HCST from MUD vs haplodonor at 1st or 2nd remission. The study was approved by the Independent Ethics Committee and the Scientific Council of the I.P. Pavlov First Saint Petersburg State Medical University. 34 children with infant acute leukemia: 23 pts with AML (68%) and 11 – with ALL (32%) – underwent allo-HSCT from MUD vs haplo at 1st or 2nd remission between 2004–2018 were analyzed. Median age at allo-HCST – 22 months (6 months – 5 y.o.). HSCT was performed from MUD in 19 (56%) pts (group 1), haplo – 15 (44%) pts (group 2). Myeloablative conditioning received 29 (85%) pts. Reduced intensity conditioning received 5 (15%) pts. Posttransplant cyclophosphomyde (PtCy) was used in 10 (53%) pts in the group 1 and 14 (93%) pts. in the group 2 (p = 0.043). Engraftment was identified in 18 pts (95%) of group 1 and 12 pts (80%) of group 2 (p = 0.28). At the median follow up 3.5 years OS is 79% in the group 1 аnd 73% in the group 2 (p = 0.68). RFS is 79% in the group 1 аnd 67% in the group 2 (p = 0.41). GRFS is 39% in the group 1 аnd 47% in the group 2 (p = 0.5). TRM occurred in 2 pts (11%) of group 1 (due to infectious and toxicity) and no one of the group 2 (p = 0.2). Haplo-HSCT with PtCy is a good alternative to MUD with high efficacy and acceptable toxicity in children with infant acute leukemia at 1st or 2nd remission.

Treatment results of hematopoietic stem cells transplantation (HSCT) with myeloablative (MAC) and reduced intensity (RIC) conditioning regimen in children and adolescents with myelodysplastic syndrome (MDS). Fifty seven patients aged 1to18 years who received allo-HSCT from 1996 to 2016 (30 patients with MAC and 29 patients with RIC) are included in the study. Analysis of overall and event-free survival in both groups showed comparable efficacy. The use of RIC as alternative conditioning regimen in children and adolescents with MDS.

Aim. To evaluate the impact of additional chromosomal aberrations on outcomes of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with acute myeloid leukemia (AML) with t(8;21)(q22;q22)/RUNX1-RUNX1T1 translocation. Methods. Twenty-five AML patients with t(8;21)(q22;q22)/RUNX1-RUNX1T1 translocation (10 women and 15 men, aged from 2 to 58 years; median 20.2) were examined. Analysis of overall (OS) and event-free survival (EFS) predictors after allo-HSCT in patients with different clinical, transplant and cytogenetic characteristics was performed. Results. The additional cytogenetic abnormalities were found in 13 (52 %) patients before the transplantation, at that, complex karyotype with three or more chromosomal abnormalities were registered in 9 (69 %) patients. The univariate analysis showed that OS and EFS after allo-HSCT differed in patients with different characteristics such as age (p = 0.03; p = 0.0006), clinical status at transplantation (p = 0.0002; p = 0,006), donor type (p = 0.0003; p = 0.002), the interval from diagnosis of leukemia to allo-HSCT (p = 0,008, for OS only), additional cytogenetic abnormalities (p = 0.03; p = 0.009) and complex karyotype (p = 0.004; p = 0.0003), respectively. In multivariate analysis, independent predictors of OS were donor type (p = 0.01), the interval from diagnosis of leukemia to allo-HSCT (p = 0.01), and additional cytogenetic abnormalities in karyotype (p = 0.04), as well as donor type (p = 0.04) and patient’s age (p = 0.004) for EFS. Conclusion. AML with t(8;21)(q22;q22)/RUNX1-RUNX1T1 translocation is a heterogeneous disease. The prognosis in patients with the additional cytogenetic abnormalities, especially in those with the complex karyotype, is worse both after the standard chemotherapy (i.e. before allo-HSCT), and after allo-HSCT.

Aim. To evaluate the prognostic impact of the different cytogenetic characteristics, including the modal number, the number of chromosomal aberrations in a complex karyotype, and adverse chromosomal abnormalities (ACA) (-7/7q-, -5/5q-, -17/17p-, t(6; 9)(p22; q34)) on the results of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with hyperdiploid acute myeloid leukemia (H-AML). Methods. Forty seven H-AML patients (21 women and 26 men, aged from 1 to 58 years, median - 23.9 years) were examined. The analysis of overall (OS) and event-free survival (EFS) predictors after allo-HSCT in patients with different clinical, transplant and cytogenetic characteristics was performed. Results. The modal number of chromosomes (MN) of 4748 was the most common one in the karyotype which was observed in 31 (66 %) patients. High hyperdiploidy with the modal number of 49-65 was identified in 13 (28 %) patients, near-triploid and near-tetraploid karyotypes were found in 3 (6 %) patients. Quantitative chromosomal abnormalities were nonrandom. Chromosome 8 (50 %), 21 (32 %), 13 (16 %) and 22 (16 %) trisomy was the most common one. Structural chromosomal abnormalities were detected in 22 (47 %) patients, at that, ACA were found in 7 (19 %) patients. In univariate analysis, the OS and EFS after allo-HSCT differed in patients with different clinical status (remission vs. active disease; p = 0.003 and p = 0.002, respectively), different chromosomal abnormalities in hyperdiploid karyotype (ACA- vs. ACA+; p = 0.001 and p = 0.03, respectively). An additional analysis of selected patients group with a structurally complex karyotype (n = 19) showed, that patients without ACA had a higher OS than patients with ACA (p = 0.03). In multivariate analysis, the disease status (relapse) at allo-HSCT was an independent predictor of decreased OS and EFS (p = 0.004 и p = 0.006, respectively), as well as the presence of the ACA (p = 0.002 only for OS). Conclusion. ACA were high-risk factors in H-AML patients received allo-HSCT. Therefore, the patients with formal criteria of a complex karyotype should not be automatically included in the cytogenetic unfavorable risk group.

Aim. To evaluate the prognostic significance of the complex karyotype including del(5q), -7, del(7q) abnormalities in acute myeloid leukemia (AML) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Materials & Methods. Forty-four AML patients with chromosome 5 and/or 7 abnormalities (22 women and 22 men, aged from 1.2 to 67 years, median 31.2 years) were examined. Analysis of overall (OS) and event-free survival (EFS) predictors after allo-HSCT in patients with different clinical, transplant and cytogenetic characteristics was performed. Results. Prior to allo-HSCT, the complex karyotype (with three or more chromosomal abnormalities) was observed in 19 (43 %) patients, the monosomal karyotype was in 8 (18 %) patients. Univariate analysis demonstrated that OS and EFS differed in patients from different age groups (> 18 vs. < 18 years; p = 0.01 and p = 0.05, respectively), with different disease status at transplantation (1 remission vs. other clinical status; p = 0.1 and p = 0.008, respectively), with and without complex karyotype (СК- vs. CK+; p = 0.05 and p = 0.002, respectively), with and without monosomal karyotype (МК- vs. MK+; p = 0.009, only for EFS), and with different stem cells source (bone marrow vs. other source; p = 0.03 only for OS). Multivariate analysis confirmed that age of 18 years and more (p = 0.02 and p = 0.01, respectively), active disease at allo-HSCT (p = 0.04 and p = 0.005, respectively), complex karyotype (p = 0.04 и p = 0.0008, respectively) and stem cell source other than bone marrow (p = 0.02 only for OS) were independent predictors of OS and EFS deterioration. Conclusion. The study demonstrates that chromosome 5 and/or 7 abnormalities as a part of the complex karyotype is high-risk factor in AML patients undergoing allo-HSCT (unlike the monosomal karyotype), that requires the special therapeutic approach.

Background. Hurler syndrome is the most severe type of mucopolysaccharidosis with central nervous system, cardio-vascular system and musculoskeletal system involvement. A unique method of radical therapy is allogenic stem cell transplantation (allo-HSCT). A question on high toxicity of HSCT is still unsolved for these patients. Aim – to estimate effectiveness and toxicity of conditioning regimen with reduce intensity in patients with Hurler syndrome. Materials and methods. Eight patients were enrolled to the investigation. Follow-up median was 20 (1–60) months. 6 patients received allo-HSCT from full HLA-matched unrelated donors, 2 patients received HSCT from partially HLA-matched unrelated donors with mismatch in A locus. The following conditioning regimens with reduce intensity were used as preparative therapy: Fludarabine – 150 mg/m2, Melphalan – 140 mg/m2, Antithymocyte Immunoglobulin (ATGAM) – 60 mg/kg. For graft-versus-host disease (GvHD) prevention Cyclosporine A in dose 1.5 mg/kg2 time per day with a combination with Methotrexate (10 mg/m2 in days +1, +3, +6) or Mycophenolate mofetil (MMF) (15 mg/kg 2 times per day during 30 days) was used. The most common transplant source were peripheral blood stem cells (PBSC) – 6 (75 %) patients, in 2 cases bone marrow was used. Due to high level of T-cells in PBSC at 3 patients, the immunomagnetic CD3/CD19-depletion or CD34+-cells depletion with the help CliniMACs device was performed. The following transplantation of CD3/CD19+-cells in dose 1.0 × 107/ kg of recipients weight in case of full-matched unrelated donor or 1.0 × 106/ kg of recipients weight in case of mismatched unrelated donor was performed. Results. Six patients are alive on a moment of analysis (median follow-up 20 (1–60) months). Overall survival of patients with Hurler syndrome after allo-HSCT is 75 %. All patients engrafted with complete donors chimerism on day +30. Alpha-L-iduronidase activity in leukocytes achieved normal level (average 61.3 nM/mg/18 h) on day +30. Activity was normal till day +100 – 77.6 nM/mg/18 h (normal indicator –61.0–175.5 nM/mg/18 h). Mixed donor’s chimerism was revealed on days +60 and +180 at two patients. No incidence of severe mucosytis III–IV gr. revealed. Two patients died due to transplant related causes. Causes of deaths: 1st patient – acute intestinal GvHD IV gr., III gr. skin GvHD, II gr. liver GvHD on day +69 from allo-HSCT, 2nd patient – TRALI-syndrome after packed red cells transfusion on day +45after allo-HSCT. Conclusion. Allo-HSCT with reduced intensity conditioning regimen for the patients with Hurler syndrome is effective method of treatment without severe toxic complication. Immunoadoptive therapy can be used for rejection prevention in case of mixed donor’s chimerism.