Immunophenotypic characteristics of multipotent mesenchymal stromal cells that affect the efficacy of their use in the prevention of acute graft vs host disease

Introduction. Over the past 5 years, signifi cant progress has been achieved in the treatment of patients with Ph-negative acute lymphoblastic leukemia (ALL). Treatment results were compared between two protocols of the Russian multicenter studies «ALL-2009» and «ALL-2016», in which multicomponent high-dose consolidation was not used. The principle of continuity of treatment was observed with modifi cation of doses of cytostatic drugs depending on the depth of cytopenia.Aim – to compare the 5-year results of two studies and to determine the factors of unfavorable prognosis in the treatment of patients with ALL.Materials and methods. The studies were performed from April 2009 to April 2016 (ALL-2009) and from April 2016 to September 2021 (ALL-2016), and 596 patients were included: 330 in ALL-2009 and 266 in ALL-2016. The analysis was performed in March 2022. The median age of patients in ALL-2009 was 28 years (15–55), in ALL-2016 – 32.5 years (18–55). Cytogenetic studies were performed in 242 patients in ALL-2009 (73.3 %) and 236 patients in ALL-2016 (88.7 %). Patients in the ALL-2016 protocol underwent a centralized assessment of minimal residual disease (MRD) by fl ow cytometry on protocol +70 day (after completion of two induction phases), +133 and +190 days. Transplantation of allogeneic stem hematopoietic cells was performed in 7 % of patients in ALL-2009 and in 9 % in ALL-2016.Results. Overall, relapse-free survival (OS, RFS) and the probability of relapse for a period of 3 years from the moment of inclusion of patients in a particular study were 59 %, 63 % and 23 % for ALL-2009, and for ALL-2016 – 64 %, 59 % and 22 %, respectively. For patients with B-cell precursor ALL, two cytogenetic risk groups were formed, in which long-term survival rates differed signifi cantly: the standard group (hyperploid set of chromosomes and normal karyotype) – OS 63 %, RFS 70 %, and high cytogenetic risk (any abnormal karyotype, except for hyperploidy) – OS 49 %, RFS 52 % (р = 0.001, р = 0.0014). In T-ALL, cytogenetic markers had no prognostic value, but the immunophenotype of early T-cell precursor turned out to be an important predictor of poor prognosis (the probability of relapse was 52 % compared with 15 % for all other immunophenotypic variants). According to the results of centralized monitoring of MRD, it was determined that for B-cell precursor ALL, the signifi cant negative factors are the high cytogenetic risk group and positive MRD status at +70 day, and for T-cells, the early immunophenotype and positive MRD status at +133 day.

Multipotent mesenchymal stromal cells (MSCs) are currently under intensive investigation for the treatment and prevention of graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT), owing to their substantial immunomodulatory properties. The responses of recipients to MSC infusion following allo-HSCT are not yet well understood. T cells are central to the adaptive immune system, protecting the organism from infection and malignant cells. Memory T cells with different phenotypes, gene expression profiles, and functional properties are critical for immune processes regulation. The aim of this study was to study the dynamics of memory T cell subpopulations and cytokines in the blood of allo-HSCT recipients after MSC administration. In clinical trial NCT01941394, patients after allo-HSCT were randomized into 2 groups, one receiving standard GVHD prophylaxis and the other also receiving MSC infusion on the day of leukocyte recovery to 1000 cells/μL (engraftment, day E0). Blood samples of patients from both groups were analyzed on days E0, E+3, and E+30. T cell subpopulations were studied by flow cytometry, and cytokine concentrations were evaluated by the Bio-Plex Pro Human Cytokine Panel. Administration of MSCs to patients on day E0 did not affect the overall dynamics of restoration of absolute numbers and proportions of T and B lymphocytes after 3 and 30 days. At 3 days after MSC injection, only the numbers of CD8⁺ effector cells (CD8⁺_TE, CD8⁺_TM, and CD8⁺_EM) were found to increase significantly. A significant increase in the number of CD4⁺ cells after 30 days compared to day E0 was observed only in patients who received MSCs, indicating faster recovery of the CD4⁺ cell population following MSC injection. An increase in CD8⁺ cell number by day E+30 was significant regardless of MSC administration. To characterize the immune status of patients following allo-HSCT in more detail, changes in the cytokine concentration in the peripheral blood of patients on days E0, E+3, and E+30 after MSC administration were investigated. On day E+30, significant increases in the numbers of CD4⁺_CM and activated CD4⁺CD25⁺ cells were observed. The concentrations of proinflammatory and anti-inflammatory cytokines IL-6, IL-8, IL-17, TNF-α, and IFN-γ were increased significantly in patients injected with MSCs. Analysis of growth factor levels showed that in the group of patients who received MSCs, the concentrations of G-CSF, GM-CSF, PDGFbb, FGFb, and IL-5 increased by day E+30. Among the cytokines involved in regulation of the immune response, concentrations of IL-9, eotaxin, IP-10, MCP-1, and MIP-1a were increased after 30 days irrespective of MSC administration. The administration of MSCs exerts a positive effect on the restoration of T cell subpopulations and immune system recovery in patients after allo-HSCT.

Introduction. The Russian multicentre trial on treatment of Acute Lymphoblastic Leukaemia (ALL) in adults (RALL-2016) regulates a centralised detection of minimal residual disease (MRD) on days 70 (end of induction II), 133 (end of consolidation III) and 190 (end of consolidation V).Aim — the assessment of tumour cell clearance and normal B-cell precursor, mature B-cell and plasma cell dynamics.Materials and methods. The study period of December 2016 — August 2019 covered 59 B-ALL patients; the control cohort included four allogeneic blood stem cell donors. The MRD detection was performed with bone marrow samples in flow cytometry.Results. The patient majority have reached MRD-negativity at control timepoints, 60.4, 75.6 and 91.2% on days 70, 133 and 190, respectively. No correlation was observed between MRD values and tumour cell immunophenotype. B-cell precursors were undetected in 54.4, 38.8 and 59.4% patients on days 70, 133 and 190, respectively. Mature B-cells were fewer compared to donors’ on days 133 and 190. The relative plasma cell count did not differ significantly over therapy and between patients and donors.Conclusion. The RALL-2016 protocol facilitates MRD-negativity in the patient majority despite reduced cytostatic intensity.