allo-HSCT In Children Research Articles

Progress of allogeneic hematopoietic stem cell transplantation in KMT2A-rearranged acute leukemia

KMT2A (lysine methyltransferase 2A) -rearranged acute leukemia is a class of leukemia with unique biological characteristics with moderate or poor prognosis. In recent years, allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been increasingly indicated for patients with KMT2A-rearranged acute leukemia. By reviewing the clinical studies of allo-HSCT in KMT2A-rearranged acute leukemia, the efficacy of allo-HSCT in children and adults with KMT2A-rearranged acute myeloid leukemia and acute lymphoblastic leukemia was assessed, the factors affecting the prognosis of allo-HSCT were summarized, and the methods that may improve the outcomes of allo-HSCT were explored.

Analysis of Safety and Efficacy of Avapritinib As Targeted Therapy for Pediatric Acute Myeloid Leukemia Patients with KIT Mutation after Transplantation

Objective: To investigate the safety and efficacy of Avapritinib in pediatric acute myeloid leukemia (AML) with KIT mutation after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods: The clinical data of 6 AML patients with KITmutation and RUNX1::RUNX1T1 fusion gene positive in Children's Hospital of Soochow University were retrospectively analyzed, including 2 cases of KIT:N822K, 3 cases of KIT: exon17 and 1 case of KIT: Asp816Tyr. After achieving complete remission in morphology, allo-HSCT was performed. The clinical outcomes of prophylactic therapy (2/6) and preemptive intervention (4/6) with Avapritinib after complete stem cell engraftment were observed, and the adverse events during treatment were recorded. Results: Adverse events occurred in 4 of the 6 patients, among whom neutropenia was the most common (4/6), followed by facial edema (2/6) and thrombocytopenia (1/6). 2 patients who received prophylactic treatment achieved morphological complete remission, and minimal residual disease (MRD), fusion gene and KIT mutations were all negative. 4 patients received preemptive intervention because of RUNX1::RUNX1T1 fusion gene turned positive after allo-HSCT, and 1 patient's RUNX1::RUNX1T1 turned negative after single-agent Avapritinib treatment for 2 months. 2 patients did not achieve continuous RUNX1::RUNX1T1 negative after preemptive therapy with Decitabine (DAC) and donor lymph infusion (DLI), and then was treated with Avapritinib, one's RUNX1::RUNX1T1 fusion achieved continuously negative after 1 month treatment of Avapritinib, the other's achieved continuous negative after 7 months treatment of Avapritinib. One patient was treated with Avapritinib after DAC and DLI as preemtive intervention, and RUNX1::RUNX1T1 fusion did not turn negative, but the relative value of RUNX1::RUNX1T1 fusion was lower than before and lived stable for more than 10 months. Conclusions: Avapritinib is safe and effective in the prophylactic and preemptive treatment of AML with KIT mutation after allo-HSCT in children, which provides a clinical drug for the prevention of relapse after transplantation.

Early Elevation of Absolute Eosinophil Count after Allogeneic Hematopoietic Stem Cell Transplantation Is Associated with Chronic Graft-Versus-Host Disease in Children

BACKGROUND Chronic graft-versus-host disease (cGVHD) is the most frequent late complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and is associated with non-relapse mortality. If recipients with cGVHD are not properly treated at the appropriate time, cGVHD can lead to severe complications. Therefore, early prediction of cGVHD is required to improve quality of life among the pediatric survivors who undergo allo-HSCT. The significance of eosinophilia in peripheral blood after allo-HSCT remains to be elucidated. Previous studies found that eosinophilia after allo-HSCT reduced the risk of relapse of malignancies or non-relapse mortality and was also associated with cGVHD. However, the subjects of these reports were mainly adults and there were limited data focused on eosinophilia after allo-HSCT in children. The aim of this study was to evaluate whether an early elevation of absolute eosinophil count after allo-HSCT was associated with the development of cGVHD in children. METHODS A total of 165 consecutive patients who received allo-HSCT in our institute were included. Patients who had previously received allo-HSCT, relapsed or died before day 100, and did not achieve engraftment, were excluded. Eosinophilia was defined as an eosinophil count of more than 500 /µL in peripheral blood within 60 days of stem cell infusion. The primary outcome of the present study was the development of cGVHD. RESULTS In our cohort, eosinophilia was detected in 67 patients (40.6%), with a median maximum eosinophil count of 1,050 /µL (range, 504 - 7,812 /µL) at a median of 40 days (range, 24 - 59 days), while median maximum eosinophil count in those without eosinophilia was 189 /µL (range, 0 - 495 /µL). There were no significant differences between the patients with or without eosinophilia in disease type, graft source, donor type, conditioning regimen, and GVHD prophylaxis and treatment. The median time from day 0 to the date of diagnosis of cGVHD was 120 days (range, 100 - 1,302 days). The cumulative incidence rate of cGVHD at 3 years in the entire cohort was 39.3% (95% confidence interval: 32.2 - 47.4). Patients with eosinophilia had a higher 3-year cumulative incidence rate of cGVHD, compared with those without eosinophilia (49.1% vs. 32.7%, P = 0.007). Cox proportional hazards model analysis with adjustments for the potential confounding factors of HLA mismatched donor, unrelated donor, aGVHD, use of ATG as conditioning regimen revealed that eosinophilia was associated with an increased risk of cGVHD (adjusted hazard ratio: 2.12; 95% confidence interval: 1.16-3.85, P = 0.014). In the 165 patients who underwent allo-HSCT, there was no significant difference in 5-year overall survival (OS) between the eosinophilia and the non-eosinophilia groups (80.1% vs. 80.5%, P=0.76). In the 121 patients with malignant diseases, there was no significant difference in 5-year OS between the eosinophilia and the non-eosinophilia groups (75.5% vs. 76.3%, P = 0.70). There was also no significant difference in 5-year disease-free survival between the eosinophilia and the non-eosinophilia groups (69.1% vs. 77.1%, P = 0.34). On the other hand, there was a significant difference in 5-year GVHD-free relapse-free survival between the eosinophilia and the non-eosinophilia groups (41.1% vs. 62.4%, P = 0.04). DISCUSSION & CONCLUSION In the present study, we revealed that an early elevation of absolute eosinophil count after allo-HSCT was associated with cGVHD in children. Because eosinophilia after allo-HSCT occurs before the development of cGVHD, early eosinophilia after allo-HSCT may predict the development of cGVHD in children.

Successful Use of Haploid Hematopoietic Stem Cell Transplantation for Severe Glanzmann's Thrombasthenia

Objective: Glanzmann's thrombasthenia (GT) is a rare autosomal recessive disorder, which characterized by the clinical manifestations from purpura to severe bleeding. It was caused by mutations of the ITGA2B or ITGB3 gene on chromosome 17, which lead to deficits or reduced expression of the platelet membrane glycoprotein GPIIb/IIIa. We report 5 pediatric patients with severe Glanzmann's thrombasthenia who underwent allogeneic hematopoietic stem cell transplant, to observe the outcomes of allo-HSCT in children with severe Glanzmann's thrombasthenia. Methods: We retrospectively summarized the clinical and genetic profiles of five patients with Glanzmann's thrombasthenia who underwent allo-HSCT from June 2021 to July 2023. All patients were reduced intensity conditioning (Bufulsan 3.2-6.4mg/kg, CTX 120mg/kg, FLU 180mg/m 2, ATG 10mg/kg). After conditioning chemotherapy, all the patients received stem cells collected via bone marrow harvest and/or peripheral blood apheresis (PBSC) with CD34 dose of 2.89-7.2×10 6/kg and received graft vs. host disease (GvHD) prophylaxis with cyclosporine (CSA) and methotrexate (MTX). Results: There were five children were involved in this observation, one patient suffered from recurrent epistaxis bleeding which was life-threatening; the second suffered from gastrointestinal bleeding and could only accept liquid diet to 10-years-old; other patients also suffered from epistaxis bleeding, gum bleeding or gastrointestinal bleeding. For all the patients, regular red cell transfusions were required, platelet transfusions and recombinant factor VIIa were also used in severe and life-threatening bleeding events. Two of the five developed antiplatelet antibodies before HSCT. All the patients were successfully treated with allo-HSCT. One case received non-relative matched donor of 10/10 HLA, one case with sibling matched donor, and 3 cases with haploid transplantation of HLA 5-6/10 matched. The mean time to neutrophil engraftment was 11 days (11-12 days), and the mean time to platelet engraftment was 16 days (15-18 days). One case had CMV reactivation, one case had HHV-6b infection, one case had grade II acute GVHD of the skin which was controlled rapidly. There was no evidence of chronic GVHD for all the patients. The platelet disorder was corrected to a normal level after allo-HSCT, with no significant complication related to the transplantation. Comparing with HLA matched donor, either from sibling or non-related, the patients receiving haploid transplantation with 5-6/10 HLA matched got similar outcome. Conclusions: We proposed haploid transplantation treated with the reduced intensity conditioning regimens produced similar outcomes as HLA matched did which could be recommended as an alternative donor for severe Glanzmann's thrombasthenia.

Risk factors for hemorrhagic cystitis in children with β-thalassemia major after allogeneic hematopoietic stem cell transplantation

To explore the risk factors for hemorrhagic cystitis (HC) in children with β-thalassemia major (TM) undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). A retrospective analysis was conducted on clinical data of 247 children with TM who underwent allo-HSCT at Shenzhen Children's Hospital from January 2021 to November 2022. The children were divided into an HC group (91 cases) and a non-HC group (156 cases) based on whether HC occurred after operation. Multivariable logistic regression analysis was used to explore the risk factors for HC, and the receiver operating characteristic curve was used to analyze the predictive efficacy of related factors for HC. Among the 247 TM patients who underwent allo-HSCT, the incidence of HC was 36.8% (91/247). Univariate analysis showed age, incompatible blood types between donors and recipients, occurrence of acute graft-versus-host disease (aGVHD), positive urine BK virus deoxyribonucleic acid (BKV-DNA), and ≥2 viral infections were associated with the development of HC after allo-HSCT (P<0.05). Multivariable analysis revealed that incompatible blood types between donors and recipients (OR=3.171, 95%CI: 1.538-6.539), occurrence of aGVHD (OR=2.581, 95%CI: 1.125-5.918), and positive urine BKV-DNA (OR=21.878, 95%CI: 9.633-49.687) were independent risk factors for HC in children with TM who underwent allo-HSCT. The receiver operating characteristic curve analysis showed that positive urine BKV-DNA alone or in combination with two other risk factors (occurrence of aGVHD, incompatible blood types between donors and recipients) had a certain accuracy in predicting the development of HC after allo-HSCT (area under the curve >0.8, P<0.05). Incompatible blood types between donors and recipients, occurrence of aGVHD, and positive urine BKV-DNA are risk factors for HC after allo-HSCT in children with TM. Regular monitoring of urine BKV-DNA has a positive significance for early diagnosis and treatment of HC.

Analysis and Modeling of Risk Factors for Children with Intestinal Acute Graft-Versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation

To analyze factors associated with intestinal acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation(allo-HSCT) in children and to develop a prediction model for intestinal aGVHD after allo-HSCT in children. The clinical data of 62 children who underwent allo-HSCT at the Department of Hematology of the People's Hospital of Xinjiang Uygur Autonomous Region from February 2018 to September 2021 were retrospectively analyzed. Intestinal aGVHD was evaluated according to the Mount Sinai Acute GVHD International Consortium (MAGIC) grading criteria, the variables were screened by LASSO (least absolute shrinkage and selection operator) regression analysis with 10-fold cross-validation, and developed a model for predicting intestinal aGVHD after allo-HSCT in children. A total of 33 (53.2%) of the 62 children developed intestinal aGVHD, of which 25 were degree II and 8 were degree III-IV. The results of screening variables by 10-fold cross-validated LASSO regression showed that the significant variables included ethnic minorities (OR =7.229; 95%CI: 2.337-22.354), platelet (PLT) (OR =0.971; 95%CI: 0.932-0.993), uric acid (UA) (OR =0.971; 95%CI: 0.935-0.988), C-reactive protein (CRP) (OR =1.217; 95%CI: 1.053-1.545), and viral infection (OR =10; 95%CI: 3.021-32.668), and these variables were independently associated with intestinal aGVHD in children (all P <0.05). A prediction model was constructed based on above variables. The area under the receiver operating characteristic (ROC) curve (AUC) of the model was calculated, and the AUC value was 0.985 (0.966-1), the Brier score was 0.055. The evaluation showed that the model has a high degree of discrimination and calibration. Ethnic minorities, low PLT, low UA, high CRP, and viral infections are independently associated with intestinal aGVHD in children, and early attention should be paid to these high-risk children.

Effect of Plasmacytoid Dendritic Cell Dose in Grafts on CMV Infection after Allogeneic Hematopoietic Stem Cell Transplantation

To investigate the correlation between plasmacytoid dendritic cell (pDC) dose in grafts and the occurrence of cytomegalovirus (CMV) infection after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The clinical data of 80 children who received allo-HSCT in Children's Hospital of Soochow University from August 20, 2020 to June 11, 2021 were retrospectively analyzed. Proportions of DC subsets and T-cell subsets in grafts were detected by flow cytometry in order to calculate infused cell dose of each cell. Weekly monitoring of CMV-DNA copies in peripheral blood for each child were performed after transplantation. The last follow-up date was December 31, 2021. All the children gained hematopoietic reconstitution. CMV infection was observed in 51 children (63.8%±5.4%) within the first 100 days after transplantation, including 2 cases developing CMV disease. Univariate analysis indicated that infused doses of DC and pDC were significantly associated with CMV infection within 100 days after allo-HSCT (P <0.05). Multivariate analysis indicated that a high dose infusion of pDC was an independent protective factor for CMV infection within 100 days after allo-HSCT (P <0.05). By the end of follow-up, 7 children died of transplantation-related complications, including 2 deaths from CMV disease, 2 deaths from extensive chronic graft-versus-host disease, and 3 deaths from capillary leak syndrome. The overall survival rate was 91.2%. The pDC in grafts may be associated with early infection of CMV after allo-HSCT, while a high infused pDC dose may serve as a protective factor for CMV infection after transplantation.

Molecular genetic and cytofluorimetric prognostic factors in the development of acute myeloid leukemia relapse in children after allogeneic hematopoietic stem cell transplantation

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 1st–2nd 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 1st or 2nd remission of the disease, 13 (26 %) were out of the 1st–2nd 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.

Results of hematopoietic stem cell transplantation in children with acute leukemia: a single-center experience

Currently, allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective treatment option for relapsed / refractory (R / R) acute leukemia (AL) and high-risk AL. In this article, we present our own experience of allo-HSCT in children with R / R AL. The study was approved by the Independent Ethics Committee and the Scientific Council of the N. N. Blokhin National Medical Research Center of Oncology. Fifty-one patients with R / R AL were included in the study: 32 patients had acute lymphoblastic leukemia (ALL), 17 patients had acute myeloid leukemia (AML) and 2 patients had biphenotypic leukemia (BL). All patients underwent allo-HSCT from January 2021 to October 2022. The median age was 8.7 years (5 months – 17 years). At the time of allo-HSCT, 26 patients were in the second (and further) remission, the rest were in the first clinical and hematologic remission (high-risk AML and refractory ALL). Twenty-one (41.2 %) patients received allo-HSCT from a haploidentical donor, 19 (37.2 %) patients underwent allo-HSCT from an HLA-matched related donor and 11 (21.6 %) patients – from an HLA-matched unrelated donor. Pre-transplant conditioning in ALL: 27 patients received regimens based on total body irradiation at a dose of 12 Gy, 4 patients received busulfan-based conditioning regimens, and in 1 patient we used treosulfan. In AML and BL, we used conditioning regimens based on treosulfan/thiotepa (n = 10), treosulfan/melphalan (n = 8) or busulfan / melphalan (n = 1). Bone marrow (in 14 patients) and peripheral blood stem cells (in 37 patients) were used as a source of hematopoietic stem cells. In haploidentical allo-HSCTs in order to prevent graft-versus-host disease (GVHD) we performed TCRab/CD19 depletion followed by additional administration of abatacept / tocilizumab / rituximab on day –1 in 15 patients, 6 patients received post-transplant cyclophosphamide. In transplantations from HLA-matched related and unrelated donors, patients received combined immunosuppressive therapy with abatacept and rituximab on day –1, and calcineurin inhibitors were used as basic immunosuppressive therapy. All patients engrafted with a median time to engraftment of 13 (range, 9 to 24) days after allo-HSCT. Eight (15.7 %) patients developed a relapse of AL at different times after HSCT (five of them are alive). At the median follow-up of 9 (5–25) months, the overall and disease-free survival survival rates were 76.4 % and 68.8 %, respectively, for patients with AL. Acute GVHD was observed in 72.5 % of children, grade 3–4 GVHD was observed in 5.3 % of patients, and 13.7 % of children developed chronic GVHD. Most patients developed infectious complications in the early post-transplant period: febrile neutropenia (96.0 %), reactivation of viremia (47.3 %,) oropharyngeal mucositis (78.4 %), acute cystitis (12.3 %). The overall mortality rate was 17.6 %. Late mortality was associated with a relapse of AL.

The frequencies of lymphocyte subsets on “day 30″ correlate with the clinical outcome of pediatric hematopoietic stem cell transplantation

We aimed to determine the relationship between lymphocyte subsets on day 30 (D30) and prognosis after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in children. We retrospectively examined the clinical outcomes and lymphocyte subsets on D30 after allo-HSCT in 115 pediatric patients at the Children's Hospital of Soochow University between January 2016 and June 2019. Measurements were performed using flow cytometry on D30. Lymphocyte subsets were compared among the umbilical cord blood (UCB) (n = 22), HLA-matched sibling donor (MSD) (n = 14), haploidentical donor transplantation (HID) (n = 57), and unrelated donor transplantation (UD) (n = 22) groups. The relationships between the frequencies and counts of lymphocyte subsets and clinical outcomes were analyzed. T and B cell counts were the highest in the MSD group compared to the other groups, and natural killer cell counts were the highest in the UCB group. Lymphocyte subsets on D30 after allo-HSCT were correlated with the occurrence of acute (aGVHD) and chronic graft versus host disease (cGVHD). A high frequency of B cells (≥4.65%) was associated with the development of severe aGVHD. High frequencies of CD4+T (≥10.25%) were correlated with extensive cGVHD. Moreover, a high frequency of CD4+T cells (≥9.80%) was correlated with GVHD-free and failure-free survival (GFFS) after allo-HSCT. However, on D30, there were no statistically significant correlations between viral infections and lymphocyte subsets. The frequencies of lymphocyte subsets on D30 after allo-HSCT are good indicators of prognosis after allo-HSCT in children.

Relationship between Iron deposition and T lymphocytes in children with β-thalassemia with haematopoietic stem cell transplantation.

β-Thalassemia cellular immunity is associated with iron overload. However, the relationship between varying degrees of iron deposition and T cell immune recovery after allogeneic haematopoietic stem cell transplantation(allo-HSCT) in children remain unclear. A retrospective analysis was performed on 84 children with β-Thalassemia undergoing sibling allo-HSCT. According to the degrees of hepatic iron deposition, patients were divided into four classes. T lymphocyte counts were measured. Hepatic iron deposition was assessed by T2* MRI. Epstein-Barr virus and cytomegalovirus infection rates and graft-vs.-host disease incidence were recorded. Immune recovery after allo-HSCT was compared between the two groups. Normal vs. mild group: CD4 cells were higher at 1, 3, and 6 months (P < 0.05), CD3 and CD8 cells were higher at 3 and 6 months, and 1 year in normal group (P < 0.05). Normal vs. moderate group: CD3 and CD4 cells were higher at 1, 3 and 6 months, and 1 year (P < 0.05), CD8 cells were higher at 1 and 3 months, and 1 year in normal group (P < 0.05). Normal vs. severe group: CD3, CD4 and CD8 cell at 1, 3 and 6 months, and 1 year in normal group (P < 0.05). Mild vs. moderate group: CD3, CD4 and CD8 cells were higher at 1 month in mild group (P < 0.05). Mild vs. severe group: CD4 cells were higher at 1, 3 and 6 month, and 1 year (P < 0.05), CD3 and CD8 cells were higher at 1 month in mild group (P < 0.05). Moderate vs. severe group: CD4 cells were higher at 3 months (P < 0.05), CD8 cells were higher at 6 months in moderate group (P < 0.05). The hepatic T2* values were positively correlated with CD3, CD4 and CD8 cells. The infection rates of Epstein-Barr virus and cytomegalovirus were significantly different among the groups (P < 0.05). Iron deposition affects immune recovery of T lymphocytes after allo-HSCT in children with β-thalassemia. The lower the levels of iron deposition, the greater the CD4 cell count.

The effect of decitabine-combined minimally myelosuppressive regimen bridged allo-HSCT on the outcomes of pediatric MDS from 10 years’ experience of a single center

BackgroundMyelodysplastic syndrome (MDS) is a rare disease in children and the treatment option before the allogeneic hematopoietic stem cell transplantation (allo-HSCT) is rarely reported. Our main objective was to report our single-center experience with the DNA-hypomethylating agent, decitabine-combined minimally myelosuppressive regimen (DAC + MMR) bridged allo-HSCT in children with MDS.MethodsTwenty-eight children with de novo MDS who underwent allo-HSCT between 2011 and 2020 were enrolled. Patients were divided into subgroups (refractory cytopenia of childhood [RCC] and advanced MDS [aMDS]) and treated by HSCT alone or pre-transplant combination treatment based on risk stratification. The patients’ clinical characteristics, treatment strategies and outcomes were retrospectively evaluated.ResultsTwenty patients with aMDS had received pre-transplant treatment (three were treated with decitabine alone, thirteen with DAC + MMR, and four with acute myeloid leukemia type [AML-type] induction therapy). DAC + MMR was well tolerated and the most common adverse events were myelosuppression and gastrointestinal reaction. DAC + MMR had shown an improved marrow complete remission (mCR) compared with AML-type chemotherapy (13/13, 100% versus 2/4, 50%, P = 0.044). The median follow-up for total cohort was 53.0 months (range, 2.3-127.0 months) and the 4-year overall survival (OS) was 71.4 ± 8.5%. In the subgroup of aMDS, pretreatment of DAC + MMR resulted in a much better survival rate than AML-type chemotherapy (84.6 ± 10.0% versus 0.0 ± 0.0%, P < 0.001).ConclusionsThe DAC + MMR bridged allo-HSCT may be recommended as a novel and effective approach.

Metagenomic Next-Generation Sequencing vs. Traditional Pathogen Detection in the Diagnosis of Infection After Allogeneic Hematopoietic Stem Cell Transplantation in Children.

Infection is a severe complication of allo-HSCT in children, however, the accurate detection of the infection is hard. In this study, we traced the records of 101 pediatric recipients with allo-HSCT to investigate the pathogens of infection, and collected 54 bronchoalveolar lavage fluid, 32 blood, and 15 cerebrospinal fluid samples. In these samples, 87 was with post-transplant infection and 14 without infection. Using the metagenomic next-generation sequencing (mNGS) and traditional pathogen detection, we compared their sensitivity and specificity to detect pathogens of infection. Our results showed that mNGS was more sensitive (89.7%) than conventional pathogen detection (21.8%), with a difference of 67.9% (P < 0.001), However, mNGS was less specific (78.5%) than traditional methods (92.9%), with a difference of 14.4% (P = 0.596). The sensitivity of mNGS for diagnosing pulmonary infections, bloodstream infections or viremia, and CNS infections post-transplant were 91.7, 85.7, and 90.9%, respectively. In contrast, the sensitivity of conventional testing for diagnosing pulmonary infections, bloodstream infections or viremia, and CNS infections post-transplant were 22.9, 21.4, and 18.2%, respectively. There were significant differences in the sensitivity of mNGS and conventional testing in BALF, blood, and CSF samples, with P values of 0.000, 0.000, and 0.002 respectively. Among the patients with pulmonary infection, 11 pathogens were both identified by mNGS and conventional testing, and 33 by mNGS only. The percentage with the mNGS-positive result was 44/48 (91.7%), including viruses (n = 12), bacteria (n = 17), fungi (n = 9) and mixed infections (n = 6). Among the patients diagnosed with fungal pneumonia (n = 9), the most prevalent pathogenic fungi were Pneumocystis jiroveci (n = 6), which were also detected in 4 patients with mixed infectious pneumonia. In the 28 blood specimens of patients with bloodstream infections or viremia, five patients were positive by both mNGS and conventional testing, 19 were positive by mNGS, and 1 was positive by traditional testing only. The percentage with the mNGS-positive results was 24/28 (85.7%), including viruses (n = 12), bacteria (n = 4), fungi (n = 3), and mixed infections (n = 5). Of the 15 CSF specimens enrolled, 11 patients were eventually diagnosed with CNS infections. Ten pathogens were identified by mNGS in the 11 patients, including viruses (n = 8), bacteria (n = 1), and fungi (n = 1). These results suggest that mNGS is more sensitive than conventional pathogen detection for diagnosing infections post HSCT in children which may help the clinic diagnosis. Pneumocystis jiroveci was the most frequent pathogen of pulmonary infections post-transplant, while viruses were the most common pathogens of CNS infections in allo-HSCT recipients.

Clinical Study of Intestinal Acute Graft-Versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation in Children

To observe the clinical characteristics, treatment and prognosis of intestinal acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in children and futher evaluate the occurring risk factors. The clinical data of 136 patients undergoing allo-HSCT in Wuhan Children's Hospital Affiliated to Tongji Medical College from August 2016 to August 2020 were retrospectively analyzed, clinical characteristics of children with intestinal aGVHD were observed. The risk factors of intestinal aGVHD were assessed by logistic regression while cumulative survival were analyzed by Kaplan-Meier method. Among 136 patients intestinal aGVHD occurred in 24 (17.6%) cases, with 4 cases of grade II, 20 cases of grade III-IV, and the median occurrence time was 28(10-63) days. The clinical manifestations were diarrhea with intermittent abdominal pain, 17 cases with nausea and vomiting, 11 cases with fresh bloody stool, and 8 cases with skin rash before intestinal aGVHD. The average time for treatment was 33(11-100) days. 18 cases received electronic colonoscopy and histopathology examination. 20 out of 24 cases achieved remission after treatment, and the total effective rate was 83.3%. Finally, 9 out of 24 cases died during the follow-up time. Survival analysis showed that the cumulative survival rate of patients with intestinal aGVHD (15/24, 62.5%) were significantly lower than those without intestinal aGVHD (101/112, 90.2%) (Log-rank test, P=0.001). Univariate analysis showed that recipient age, sex, primary disease, donor age, donor sex, donor-recipient blood type, conditioning regimen, prophylaxis of GVHD, dosage of ATG, engraft time of blood platelet and neutrophils, and number of MNC/CD34+ were not risk factors for intestinal aGVHD (P>0.05). Only the type of HSCT (χ2=16.020, P=0.001) and matched degree of HLA (χ2=15.502, P=0.001) had statistical significance with intestinal aGVHD (P<0.05). Multivariate analysis showed that only HLA-mismatched unrelated donor was the risk factor for intestinal aGVHD for children (P=0.014，OR=16，95%CI 1.735-147.543). Intestinal aGVHD is a risk factor for cumulative survial of patients who received allo-HSCT in children and HLA-mismatched unrelated donor is its independent risk factor.

Superior Overall Survival with Blinatumomab Versus Chemotherapy As Pre-Transplant Consolidation Treatment in Children with High-Risk First-Relapse B-Cell Precursor Acute Lymphoblastic Leukemia (B-ALL): Longer Follow-up (FU) of a Phase 3 Randomized Controlled Trial (RCT)

Superior Overall Survival with Blinatumomab Versus Chemotherapy As Pre-Transplant Consolidation Treatment in Children with High-Risk First-Relapse B-Cell Precursor Acute Lymphoblastic Leukemia (B-ALL): Longer Follow-up (FU) of a Phase 3 Randomized Controlled Trial (RCT)

The Relationship between Plasma sST2/Reg3α Levels and Acute Graft-Versus-Host Disease in Children After Allogeneic Hematopoietic Stem Cell Transplantation

To explore the relationship between plasma sST2/Reg3α levels and acute graft-versus-host disease (aGVHD) in children after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The clinical data of 29 pediatric patients received allo-HSCT treatment in Department of Hematology and Oncology of Wuhan Children's Hospital from January 2019 to January 2020 were collected. Peripheral blood samples were collected at 14 and 28 day after allo-HSCT. The plasma concentrations of sST2 and Reg3α were detected by Luminex assay. Among 29 patients there were 15 males and 14 females with a median age of 53 (29-117) months. After allo-HSCT, 18 patients developed grade 0-I aGVHD; while 11 patients developed grade II-IV aGVHD. These included skin aGVHD in 6 cases, gastrointestinal aGVHD (GI-aGVHD) in 3 cases and gastrointestinal/skin aGVHD in 5 cases. Plasma sST2 level in II-IV aGVHD group showed significantly higher than that in 0-I aGVHD group at 28 days after allo-HSCT [101.81 (73.94-150.77) ng/ml vs 48.97 (28.82-56.69) ng/ml, P=0.021]. Also, the plasma sST2 level was significantly higher in GI-aGVHD group than that in no-aGVHD group at 28 days after allo-HSCT [118.74 (87.00-243.36) ng/ml vs 48.97 (23.55-61.40) ng/ml, P=0.004]. Plasma sST2 level ≥65.34 ng/ml at 28 days after allo-HSCT showed a sensitivity of 85.7% and a specificity of 87.5% in predicting II-IV aGVHD. And the patients with a plasma sST2 level ≥65.34 ng/ml showed a significantly higher incidence of II-IV aGVHD than those with plasma sST2 level of < 65.34 ng/ml after allo-HSCT (P=0.021). There was no significant difference in plasma Reg3α level between the patients with II-IV aGVHD and the non-aGVHD ones. The increasing plasma sST2 level after allo-HSCT in children indicates the development of II-IV aGVHD, so sST2 is promising as a biomarker for predicting II-IV aGVHD.

Allogeneic hematopoietic stem cell transplantation in children with lymphoblastic lymphoma

Lymphoblastic lymphoma (LBL) in children is curable in most cases, but there is still a significant proportion of patients in whom standard therapy is ineffective. Thus, patients develop a relapse or a primary refractory disease in about 10% of cases (R/R). In this case, the main treatment method is allogeneic hematopoietic stem cell transplantation (allo-HSCT). The choice in favor of transplantation is predominantly based on the experience in adult patients. A small number of pediatric patients accounts for the limited data in pediatrics. The prognosis of these patients is always extremely poor. It has been shown that the survival of patients after allo-HSCT is higher only if remission is achieved prior to the transplantation. In order to provide more evidence in support of allo-HSCT, randomized clinical trials are needed. However, such studies in the field of allo-HSCT are quite difficult to conduct, and this necessitates the search for alternative methods of evidence-based medicine in this area. Probably, the achievement of high survival rates could be considered a sufficient argument in favor of this method. This study was approved by the Independent Ethics Committee and the Scientific Council of the I.P. Pavlov First Saint-Petersburg State Medical University of the Ministry of Healthcare of Russia. In this work, we summarize the experience in allo-HSCT in children with R/R LBL obtained at the R.M. Gorbacheva Research Institute for Pediatric Oncology, Hematology and Transplantation, I.P. Pavlov First Saint-Petersburg State Medical University. This work is one of the few ones devoted exclusively to the role of alloHSCT in the treatment of pediatric R/R LBL. From 2006 to 2020, at the R.M. Gorbacheva Research Institute for Pediatric Oncology, Hematology and Transplantation, I.P. Pavlov First Saint-Petersburg State Medical University, allo-HSCT was performed in 13 children and adolescents with R/R LBL (2 patients underwent 2 transplantations). Repeated transplantations were performed due to progression and primary graft failure. The median number of prior lines of therapy was 2.5 (2–4). Remission prior to alloHSCT was observed in 7 cases. The graft sources were a fully HLA-matched related donor (n = 3), a fully HLA-matched unrelated donor (n = 4), and a haploidentical donor (n = 8). The following schedules were used as a conditioning regimen: fludarabine 150 mg/m2 + busulfan 8–14 mg/kg (n = 8), fludarabine 150 mg/m2 + melphalan 140 mg/m2 (n = 5), fludarabine 150 mg/m2 + treosulfan 30 mg/m2 (n = 2). In most cases, the prevention of “graft versus host” disease (GVHD) was based on post-transplant cyclophosphamide (n = 11). Cyclophosphamide alone was used in fully matched related transplantation (n = 2), in combination with tacrolimus and cellsept – in unrelated transplantation (n = 1), and in combination with sirolimus and tacrolimus – in haploidentical transplantation (n = 8). A combination of ATGAM, methotrexate and cyclosporin A was used three times in alloHSCT from an unrelated donor for the prevention of GVHD. In one allo-HSCT from a fully matched related donor, cyclosporin A alone was used for the prevention of GVHD. The graft sources were bone marrow (n = 9) and peripheral blood stem cells (n = 4). The median CD34+ cells/kg was 3.8 (1.1–10.0). At the median follow-up of 651 (106–3034) days, the 3-year event-free survival rate was 52% (95% CI: 25–74), the incidence of relapse/progression was 48% (95% CI: 26–76). Five out of thirteen patients died during the study period. The cause of death was the underlying disease in all cases. The cumulative incidence of acute and chronic GVHD was 28% (95% CI: 11–58%) and 24% (95% CI: 5–48), respectively. This work is one of the largest in terms of the number of transplanted children with R/R LBL. Our results are superior to those obtained in case of using only chemotherapy in comparison with the historical control and are comparable with the few previously published data on allo-HSCT in children. In this study, we included patients who underwent allo-HSCT. Among them, there were also children out of remission of LBL which implies that there was no selection of patients, and thus our study settings were close to the so-called real clinical settings. The drawbacks of this work include the following: the study was carried out at a single transplant center, there was no comparison group, the number of patients was low. Nevertheless, considering the complexity of conducting randomized trials in the field of allo-HSCT, the presented data serve as an important confirmation of the effectiveness of transplantation in R/R LBL.

Hb-adjusted DLCO with GLI reference predicts long-term survival after HSCT in children.

This study aimed to evaluate the pretransplant diffusing capacity as a predictor of outcomes in pediatric allogeneic hematopoietic stem cell transplantation (allo-HSCT). Retrospective cohort study of 176 children followed outcomes for 5 years after allo-HSCT. We conducted an analysis of PFTs include spirometry, body plethysmography, and diffusing capacity prior to allo-HSCT. We analyzed the probabilities of overall survival (OS), disease-related mortality (DRM), and non-relapse mortality (NRM). Of all carbon monoxide diffusing capacity (DLCO) parameters obtained using the Global Lung Function Initiative (GLI)-2017, univariate analysis showed that the grade 3, 4 of DLCOadj and Category III, IV of LFS significantly increase NRM (p = 0.003 and p = 0.008). Multivariate analysis indicated that a significant increase in the risk of NRM is associated with grades 3, 4 DLCOadj (hazard ratio [HR] = 4.90, p = 0.020). Kaplan-Meier analyses showed that a significant stepwise increase in NRM was observed with both worse pretransplant DLCOadj grades and LFS categories (p < 0.001 and p = 0.003). A compromised pretransplant diffusing capacity and a high LFS significantly increase the risk of NRM. Especially, DLCOadj before transplantation can be used as an important predictor of NRM after allo-HSCT in children with malignancy.

Eltrombopag for treatment of thrombocytopenia after allogeneic hematopoietic cell transplantation in children: Single-centre experience.

Delayed recovery of thrombocytopenia is a well-known complication after allogeneic HSCT. Eltrombopag (ELT), a thrombopoietin receptor agonist (TRAs), induces platelet maturation and release. Mostly conducted in adults, some of the previous studies have shown that ELT seems to enhance platelet recovery for post-allogeneic HSCT thrombocytopenia, appears efficacious, and offers transfusion independence. To evaluate the safety and efficacy of ELT in pediatric patients with prolonged isolated thrombocytopenia (PIT) or secondary failure of platelet recovery (SFPR) after alloHSCT. Retrospective analysis of childhood patients who received treatment with ELT for persistent thrombocytopenia after alloHSCT between May 2016 and August 2019. We evaluated the safety and efficacy of ELT in 18 childhood patients with PIT or SFPR after alloHSCT. Eltrombopag (50mg/d) treatment was started in all patients, above 6years of age and 20kg weight, who had thrombocytopenia despite neutrophil engraftment on the 30th day of HSCT. Our objective was to decrease the need for platelet transfusion and have a platelet count of more than 50000/µL. The overall response rate was 77.7%. The median time to achieve a platelet level above 30000/µL and 50000/µL was 21 and 44days, respectively. In four patients, platelet count never reached 30000/mm3 . In two patients, the treatment was discontinued due to grade 3 hepatotoxicity. Our study supports the efficacy and relative safety of ELT use for the treatment of PIT and SFPR seen after alloHSCT in children.

Risk Factors for Overall Survival in Children with High Risk Acute Myeloid Leukemia (HR AML) after Allogeneic Hematopoietic Stem Cell Transplantation (allo-HSCT) with Different Intensity of Conditioning Regimens

Background: Traditionally, children with AML undergo аllo-HSCT with myeloablative conditioning (MAC). It is known that MAC is associated with significant transplant-related morbidity and mortality. Reduced-intensity conditioning (RIC) is used in patients not eligible for conventional conditioning therapy due to poor performance status and severe toxic complications after previous chemotherapy. RIC is a well-established treatment strategy in adult patients with comorbidities. But there is no conclusive evidence to support efficacy of RIC allo-HSCT in children suffering from different malignant diseases including AML. The aim: To compare efficacy of different intensity conditioning regimens in children with high risk (HR) AML (according to AML-BFM protocols 1998 and 2004) and to identify factors which have a prognostic significance for overall survival (OS). Patients and methods: Retrospective analysis was performed in 192 patients (pts) with AML (median age of 10 years (0.5-18 y.o.), who received allo-HSCT at R.M. Gorbacheva Research Institute between 08/2000 and 09/2019. MAC (busulfan- or treosulfan-based) were used in 109 pts: 1st CR - 46 pts (MRD+ n=11), 2nd CR - 18 pts, 3rd CR - 1 pt, relapse - 44 pts. Allo-HSCT with RIC were performed in 83 pts: 1st CR - 32 pts (MRD+ n=13), 2nd CR -19 pts, 3rd CR - 4 pts, relapse -28 pts (p=0,674). RIC consisted of fludarabine (30 mg/m2/d x 5 days) + melphalan (70 mg/m2/d x 2 days) or fludarabine (30 mg/m2/d x 5 days) + busulfan (4 mg/kg/d x 2 days). Indication for RIC allo-HSCT was poor performance status (Lansky/Karnofsky score ≤70%), or organ dysfunction due to previous therapy, or infectious complications at the moment of allo-HSCT. Allo-HSCT from matched related donor was performed in 30 pts (16%), from matched unrelated donor - in 98 pts (51%), haploidentical - in 64 pts (33%) and the donor distribution was not different between groups (p=0,878). Post-transplant Cy was included in GVHD prophylaxis regimens in 102 pts (53%). OS were estimated using Kaplan-Meier curves. Univariate analyses were performed using the log rank test for OS, Grey test for cumulative incidences. Multivariate analyses were performed using the Cox proportional-hazard model. Results: Median follow-up was 5 years for МАС, 4.5 years for RIC. In both groups the median time to neutrophil engraftment &amp;gt;=0,5x109/l was D+16 (range D+8-52). Engraftment was observed in 67 pts (81%) after RIC and 94 pts (86%) after MAC (p=0,231). OS after RIC allo-HSCT in the 1st CR was 76% and after MAC - 68% (p=0,014), in 2nd CR 50% after RIC and 54% after MAC (p=0,058), in advanced disease 14% after RIC and 16% after MAC (p=0,394). The transplant-related mortality rate was 19% after RIC and 22% after MAC (p=0,546). Risk of relapse was 28% after RIC and 26% after MAC (p=0,456). Factors influencing OS after MAC were: 1) Remission status at the moment of allo-HSCT (р=0.001); 2) Presence of aGVHD grade I-II (р=0,005); 3) Relapse or MRD+ status after allo-HSCT (р=0.012); 4) Lansky score &amp;gt;70% (р=0,024). Factors influencing OS after RIC were: 1) Remission status at the moment of allo-HSCT (1st remission) (p=0,001); 2) Lansky score &amp;gt;70% (р=0,004). Conclusion: The effectiveness of RIC and MAC is comparable in children with HR AML, but RIC demonstrated better results in 1st CR. The presence of I-II grade aGVHD had positive effect in MAC. Factors influencing OS in both groups were disease status at the moment of allo-HSCT and performance status before allo-HSCT The use of RIC can be effective in patients, especially those who have undergone allo-HSCT in the 1st remission, while minimizing regimen-related toxicity in children who have undergone previous intensive treatment. Multicenter studies are warranted, especially for patients in the first CR, where long-term complications are of most importance. Disclosures No relevant conflicts of interest to declare.