Pediatric acute myeloid leukemia with t(8;21) and KIT mutation treatment with avapritinib post-stem cell transplantation: a report of four cases.

Acute myeloid leukemia (AML) with t(8;21) (q22;q22), which forms RUNX1::RUNX1T1 fusion gene, is classified as a favorable-risk group. However, the presence of mutations in KIT exon 17 results in an adverse prognosis in this group. Avapritinib, a novel tyrosine kinase inhibitor, was designed to target KIT mutation. We report a retrospective study of four pediatric patients with AML with t(8:21) and KIT exon 17 mutation who were treated with avapritinib, three of them failed to demethylate drugs and donor lymphocyte infusion targeting RUNX1::RUNX1T1-positivity after allogeneic hematopoietic stem cell transplantation (allo-HSCT). So far, all patients with RUNX1::RUNX1T1 positivity had turned negative after 1, 9, 7, 2 months of avapritinib treatment. The common adverse effect of avapritinib is neutropenia, which is well-tolerated. This case series indicates that avapritinib may be effective and safe for preemptive treatment of children with AML with t(8;21) and KIT mutation after allo-HSCT, providing a treatment option for preventing relapse after allo-HSCT.

Infectious complications in pediatric patients undergoing CD19+CD22+ chimeric antigen receptor T-cell therapy for relapsed/refractory B-lymphoblastic leukemia.

Chimeric antigen receptor T-cell (CAR-T) therapy is effective in the treatment of relapsed/refractory acute B-lymphoblastic leukemia (R/R B-ALL); however, patients who receive CAR-T therapy are predisposed to infections, with considerable detrimental effects on long-term survival rates and the quality of life of patients. This study retrospectively analyzed infectious complications in 79 pediatric patients with R/R B-ALL treated with CAR-T cells at our institution. Overall, 53 patients developed 88 infections. Nine patients experienced nine infections during lymphodepletion chemotherapy, 35 experienced 41 infections during the early phase (days 0-+ 30 after infusion), and 29 experienced 38 infections during the late phase (day + 31-+ 90 after infusion). Pathogens were identified in 31 infections, including 23 bacteria, seven viruses, and one fungus. Four patients were admitted to the intensive care unit for infection and one died. In a univariate analysis, there were ten factors associated with infection, including tumor load, lymphodepleting chemotherapy, neutrophil deficiency and lymphocyte reduction, cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), etc. In a multivariate analysis, CRS ≥ grade 3 was identified as a risk factor for infection (hazard ratio = 2.41, 95% confidence interval: 1.08-5.36, P = 0.031). Therefore, actively reducing the CRS grade may decrease the risk of infection and improve the long-term quality of life of these patients.

[Clinical Analysis of Philadelphia Chromosome-Like Acute Lymphoblastic Leukemia in Children].

OBJECTIVE: To explore the clinical characteristics, molecular characteristics, treatment and prognosis of pediatric Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) with a therapeutic target. METHODS: A total of 27 patients of Ph-like ALL with targeted drug target were initially diagnosed in Children's Hospital of Soochow University from December 2017 to June 2021. The data of age, gender, white blood cell (WBC) count at initial diagnosis, genetic characteristics, molecular biological changes, chemotherapy regimen, different targeted drugs were given, and minimal residual disease (MRD) on day 19, MRD on day 46, whether hematopoietic stem cell transplantation (HSCT) were retrospective analyed, and the clinical characteristics and treatment effect were summarized. Survival analysis was performed by Kaplan-Meier method. RESULTS: The intensity of chemotherapy was adjusted according to the MRD level during induced remission therapy in 27 patients, 10 patients were treated with targeted drugs during treatment, and 3 patients were bridged with HSCT, 1 patient died and 2 patients survived. Among the 24 patients who did not receive HSCT, 1 patient developed relapse, and achieved complete remission (CR) after treatment with chimeric antigen receptors T cells (CAR-T). The 3-year overall survival, 3-year relapse-free survival and 3-year event-free survival rate of 27 patients were (95.5±4.4)%, (95.0±4.9)% and (90.7±6.3)% respectively. CONCLUSION: Risk stratification chemotherapy based on MRD monitoring can improve the prognosis of Ph-like ALL in children, combined with targeted drugs can achieve complete remission as soon as possible in children whose chemotherapy response is poor, and sequential CAR-T and HSCT can significantly improve the therapeutic effect of Ph-like ALL in children whose MRD is continuously positive during induced remission therapy.

Prognostic implications of CD9 in childhood acute lymphoblastic leukemia: insights from a nationwide multicenter study in China.

The outcomes of children with acute lymphoblastic leukemia (ALL) have been incrementally improved with risk-directed chemotherapy but therapy responses remain heterogeneous. Parameters with added prognostic values are warranted to refine the current risk stratification system and inform appropriate therapies. CD9, implicated by our prior single-center study, holds promise as one such parameter. To determine its precise prognostic significance, we analyzed a nationwide, multicenter, uniformly treated cohort of childhood ALL cases, where CD9 status was defined by flow cytometry on diagnostic samples of 3781 subjects. CD9 was expressed in 88.5% of B-ALL and 27.9% of T-ALL cases. It conferred a lower 5-year EFS and a higher CIR in B-ALL but not in T-ALL patients. The prognostic impact of CD9 was most pronounced in the intermediate/high-risk arms and those with minimal residual diseases, particularly at day 19 of remission induction. The adverse impact of CD9 was confined to specific cytogenetics, notably BCR::ABL1+ rather than KMT2A-rearranged leukemia. Multivariate analyses confirmed CD9 as an independent predictor of both events and relapse. The measurement of CD9 offers insights into patients necessitating intervention, warranting its seamless integration into the diagnostic marker panel to inform risk level and timely introduction of therapeutic intervention for childhood ALL.

Congenital dyserythropoietic anemia type II in a newborn with a novel compound heterozygous mutation in the SEC23B: a case report and review of the literature.

Congenital dyserythropoietic anemia type II (CDA II) refers to a group of extremely rare heterozygous disorders characterized by ineffective erythropoiesis and morphological abnormalities of erythrocytes and bone marrow erythroblasts. Six types of CDA with differing heterogenous genetic mutations have been identified to date. Due to the genetic and clinical heterogeneity of CDA, accurate diagnosis can be very challenging, especially with the clinical overlap observed between CDA and other dyserythropoietic diseases. A 1-month-old infant girl, born to a non-consanguineous family, presented with severe normocytic anemia that required transfusions every 2 to 3 weeks since birth, as well as jaundice. Whole exome sequencing revealed a novel compound heterozygosity in the SEC23B gene, thus establishing the diagnosis of CDA II. Analysis by multiple bioinformatics tools predicted that the mutant proteins were deleterious. Here, we report a novel variation in SEC23B that extends the mutation spectrum of SEC23B in the diagnosis of CDA II.

The influence of methotrexate-related transporter and metabolizing enzyme gene polymorphisms on peri-engraftment syndrome and graft-versus-host disease after haplo-hematopoietic stem cell transplantation in pediatric patients with malignant hematological diseases.

Background: Methotrexate (MTX), utilized as a graft-versus-host disease (GvHD) prophylactic agent in allogeneic hematopoietic stem cell transplantation (allo-HSCT), has been proven to effectively decrease the occurrence of the peri-engraftment syndrome (Peri-ES) and acute GvHD (aGvHD). Changes in the pharmacodynamics of MTX are closely associated with gene polymorphisms in genes encoding drug-metabolizing enzymes and transporters. Nevertheless, the current studies mainly concentrate on leukemia or autoimmune diseases, and limited studies on allo-HSCT were reported. Methods: Here, we retrospectively assessed the relationship between MTX-related transporter and metabolizing enzyme gene polymorphisms, clinical characteristics, and outcomes in 57 pediatric patients who received haploid HSCT (haplo-HSCT) with malignant tumors at a single center. Results: We discovered all gene polymorphisms were in the Hardy-Weinberg equilibrium in our cohort. We discovered a significant correlation between platelet recovery time and ABCB1 (1236C>T) (p = 0.042). Compared with patients with SLCO1B1 (1865+4846T>C) TT, patients with SLCO1B1 (1865+4846T>C) TC/CC had an increased incidence of Peri-ES (p = 0.030). Based on the multivariate Cox analysis, we discovered that SLCO1B1 (1865+4846T>C) TT genotype was an independent protective factor for Peri-ES morbidity (hazard ratio (HR) = 0.464, p = 0.031), and the dose of mononuclear cells reinfused was significantly correlated with II-IV aGvHD (HR = 2.604, p = 0.039). Conclusion: In summary, our findings prove that the host's genotypes might modify the risk of developing Peri-ES, contribute to a better understanding of the inter-individual difference in efficacy, and facilitate the development of individualized approaches to GvHD prophylaxis.

Short-course blinatumomab for refractory/relapse precursor B acute lymphoblastic leukemia in children.

Objective: To evaluate the clinical efficacy and safety of a short course of blinatumomab in children with refractory or relapsed precursor B-cell acute lymphoblastic leukemia (R/R-BCP-ALL). Methods: The clinical data of 33 R/R BCP-ALL children aged 0-18 years who underwent a short course of blinatumomab (14 days) between August 2021 and November 2022 were retrospectively collected and analyzed. Results: Among 33 patients with BCP-ALL, 26 achieved complete remission (CR), with a total remission rate of 78.8% (26/33). The duration of remission was approximately 14 days. Of the 7 children without CR, 5 were still in remission at 28 days. In 11 patients with refractory disease and 22 with recurrence, the remission rates were 90.9% (10/11) and 72.7% (16/22), respectively. The overall survival (OS) rates of the 26 patients with CR and seven patients without CR were 96.1% and 57.1% (p = 0.002), respectively, and the disease-free survival (DFS) rates were 96.1% and 42.9% (p < 0.001), respectively. Among the 26 patients with CR, 15 underwent bridging hematopoietic stem cell transplantation (HSCT) and 11 did not receive HSCT; with OS rates of 93.3% and 100% (p = 0.40) and DFS rates of 93.3% and 100% (p = 0.400), respectively. The OS for all patients was 87.9% (29/33) and the DFS was 84.8% (28/33). There were 18 cases (54.5%) of cytokine release syndrome (CRS), 2 cases (6.1%) of severe CRS (all grade 3), 1 case (3.0%) of immune effector cell-associated neurotoxicity syndrome (ICANS), 0 cases (0%) of ICANS ≥ grade 3, and no deaths caused by treatment. Conclusions: Short-term follow-up revealed a high R/R BCP-ALL remission rate in children treated with a short course of blinatumomab. The toxicity was low and controllable. No significant short-term survival benefits were observed after bridging HSCT with blinatumomab. In developing countries, a short course of blinatumomab can achieve satisfactory outcomes, while reducing household costs and saving medical resources.

Single-cell transcriptomics reveals multiple chemoresistant properties in leukemic stem and progenitor cells in pediatric AML.

BACKGROUND: Cancer patients can achieve dramatic responses to chemotherapy yet retain resistant tumor cells, which ultimately results in relapse. Although xenograft model studies have identified several cellular and molecular features that are associated with chemoresistance in acute myeloid leukemia (AML), to what extent AML patients exhibit these properties remains largely unknown. RESULTS: We apply single-cell RNA sequencing to paired pre- and post-chemotherapy whole bone marrow samples obtained from 13 pediatric AML patients who had achieved disease remission, and distinguish AML clusters from normal cells based on their unique transcriptomic profiles. Approximately 50% of leukemic stem and progenitor populations actively express leukemia stem cell (LSC) and oxidative phosphorylation (OXPHOS) signatures, respectively. These clusters have a higher chance of tolerating therapy and exhibit an enhanced metabolic program in response to treatment. Interestingly, the transmembrane receptor CD69 is highly expressed in chemoresistant hematopoietic stem cell (HSC)-like populations (named the CD69+ HSC-like subpopulation). Furthermore, overexpression of CD69 results in suppression of the mTOR signaling pathway and promotion of cell quiescence and adhesion in vitro. Finally, the presence of CD69+ HSC-like cells is associated with unfavorable genetic mutations, the persistence of residual tumor cells in chemotherapy, and poor outcomes in independent pediatric and adult public AML cohorts. CONCLUSIONS: Our analysis reveals leukemia stem cell and OXPHOS as two major chemoresistant features in human AML patients. CD69 may serve as a potential biomarker in defining a subpopulation of chemoresistant leukemia stem cells. These findings have important implications for targeting residual chemo-surviving AML cells.

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

OBJECTIVE: 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). METHODS: 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. RESULTS: 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%. CONCLUSION: 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.

Transcriptome sequencing identifies novel EVX fusions involved in transcriptional activation of HOX family genes in pediatric immature T-cell acute lymphoblastic leukemia: two cases reports and a literature review.

Driver genomic alterations in pediatric immature T-cell acute lymphoblastic leukemia are not fully known. We report two cases of novel EVX fusions involved in the transcriptional activation of HOX family genes, ETV6::EVX2 and MSI2::EVX1/HOXA13, which activate HOXD and HOXA cluster genes transcription through enhancer hijacking. HOXA and HOXD were the only key transcription factors activated in these cases, which indicates their important roles in leukemogenesis. Our findings elucidate potential drivers for development of T-cell lymphoblastic leukemia, and are valuable for diagnosis and risk stratification of pediatric T-ALL in the era of precision medicine.

Intragenic ß-synuclein rearrangements in malignancy.

The synuclein family, consisting of α-, ß-, and γ-synuclein, is primarily expressed in neurons. Mutations of α- and ß-synuclein have been linked to Parkinson's disease and dementia with Lewy bodies, respectively. Recent studies have shown that synucleins are upregulated in various tumors, including breast, ovarian, meningioma, and melanoma, and high synuclein expression is associated with poor prognosis and drug resistance. We report a novel rearrangement of ß-synuclein in a pediatric T-cell acute lymphoblastic leukemia (T-ALL) case, where ß-synuclein (SNCB) is fused in-frame with ETS variant transcription factor 6 (ETV6), a gene frequently rearranged in acute leukemia including acute myeloid leukemia (AML), B-cell acute lymphoblastic leukemia (B-ALL), and T-ALL. An additional case of ß-synuclein rearrangement was identified in a squamous cell carcinoma of the lung through analysis of the public TCGA database. Both rearrangements involve the C-terminal of ß-synuclein. Since ß-synuclein shares extensive amino acid similarities with α-synuclein and α-synuclein binds to 14-3-3, an important regulator of apoptosis, the rearranged ß-synuclein may contribute to tumorigenesis by deregulating apoptosis. In addition, overexpression of synucleins has been shown to increase cell proliferation, suggesting that the rearranged ß-synuclein may also deregulate the cell cycle.

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.

Coadministration of CD19- and CD22-Directed Chimeric Antigen Receptor T-Cell Therapy in Childhood B-Cell Acute Lymphoblastic Leukemia: A Single-Arm, Multicenter, Phase II Trial.

PURPOSE: We determined the safety and efficacy of coadministration of CD19- and CD22-chimeric antigen receptor (CAR) T cells in patients with refractory disease or high-risk hematologic or isolated extramedullary relapse of B-acute lymphoblastic leukemia. PATIENTS AND METHODS: This phase II trial enrolled 225 evaluable patients age ≤ 20 years between September 17, 2019, and December 31, 2021. We first conducted a safety run-in stage to determine the recommended dose. After interim analysis of the first 30 patients treated (27 at the recommended dose) showing that the treatment was safe and effective, the study enrolled additional patients according to the study design. RESULTS: Complete remission was achieved in 99.0% of the 194 patients with refractory leukemia or hematologic relapse, all negative for minimal residual disease. Their overall 12-month event-free survival (EFS) was 73.5% (95% CI, 67.3 to 80.3). Relapse occurred in 43 patients (24 with CD19+/CD22+ relapse, 16 CD19-/CD22+, one CD19-/CD22-, and two unknown). Consolidative transplantation and persistent B-cell aplasia at 6 months were associated with favorable outcomes. The 12-month EFS was 85.0% (95% CI, 77.2 to 93.6) for the 78 patients treated with transplantation and 69.2% (95% CI, 60.8 to 78.8) for the 116 nontransplanted patients (P = .03, time-dependent covariate Cox model). All 25 patients with persistent B-cell aplasia at 6 months remained in remission at 12 months. The 12-month EFS for the 20 patients with isolated testicular relapse was 95.0% (95% CI, 85.9 to 100), and for the 10 patients with isolated CNS relapse, it was 68.6% (95% CI, 44.5 to 100). Cytokine release syndrome developed in 198 (88.0%) patients, and CAR T-cell neurotoxicity in 47 (20.9%), resulting in three deaths. CONCLUSION: CD19-/CD22-CAR T-cell therapy achieved relatively durable remission in children with relapsed or refractory B-acute lymphoblastic leukemia, including those with isolated or combined extramedullary relapse.[Media: see text].

Association between haploidentical hematopoietic stem cell transplantation combined with an umbilical cord blood unit and graft-versus-host disease in pediatric patients with acquired severe aplastic anemia.

Background: Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) based on granulocyte colony-stimulating factor plus anti-thymocyte regimens ('Beijing Protocol') provides a salvage treatment for patients of acquired severe aplastic anemia (SAA) in China. However, graft-versus-host disease (GVHD) is a major impediment of haplo-HSCT due to human leukocyte antigen disparity. Recently, haplo-HSCT combined with umbilical cord blood (UCB) (haplo-cord HSCT) is performed in clinical trials to potentially reduce the risk of severe GVHD. Nevertheless, studies comparing GVHD in pediatric patients receiving haplo and haplo-cord HSCT for SAA are limited. Objective: The objective of this study was to investigate the impact of UCB co-infusion on GVHD in pediatric patients receiving haplo-HSCT for SAA. Design: We conducted a retrospective study of 91 consecutive SAA children undergoing haploidentical transplantation based on the 'Beijing Protocol' with or without co-infusion of UCB in our center. Methods: All patients received uniform non-myeloablative conditioning and GVHD prophylaxis. We compared baseline characteristics and transplant outcomes between the haplo (n = 35) and haplo-cord (n = 56) recipients. Results: All 91 patients achieved hematopoietic recovery from haploidentical donors, with a higher incidence of peri-engraftment syndrome observed with the haplo-cord group as compared with the haplo group (75.0% versus 48.6%, p = 0.029). Notably, the haplo-cord group showed a lower incidence of II-IV acute GVHD (aGVHD) than the haplo group (16.1% versus 42.9%, p = 0.002). Observed incidences of chronic GVHD (cGVHD) and moderate to severe cGVHD in the haplo-cord group were also lower than that in the haplo group (25.6% versus 51.3%, p = 0.019; 16.2% versus 41.3%, p = 0.016, respectively). Haplo-cord HSCT was identified as the only factor associated with a lower incidence of II-IV aGVHD and cGVHD in multivariate analysis. However, no differences were observed between the two groups for infections and survival outcomes. Conclusion: Our data indicated that co-infusion of UCB in 'Beijing Protocol'-based haplo-HSCT may be effective for reducing the risk of severe GVHD in SAA children.

A prospective multicenter study on varicella-zoster virus infection in children with acute lymphoblastic leukemia.

Background and methods: The study evaluated prognostic factors associated with varicella-zoster virus (VZV) infection and mortality in children with acute lymphoblastic leukemia (ALL) using data from the multicenter Chinese Children's Cancer Group ALL-2015 trial. Results: In total, 7,640 patients were recruited, and 138 cases of VZV infection were identified. The incidence of VZV infection was higher in patients aged ≥ 10 years (22.5%) and in patients with the E2A/PBX1 fusion gene (11.6%) compared to those aged < 10 years (13.25%, P = 0.003) or with other fusion genes (4.9%, P = 0.001). Of the 10 deaths in children with ALL and VZV infection, 4 resulted from VZV complications. The differences between groups in the 5-year overall survival, event-free survival, cumulative recurrence, and death in remission were not statistically significant. The proportion of complex infection was higher in children with a history of exposure to someone with VZV infection (17.9% vs. 3.6%, P = 0.022). Conclusion: VZV exposure was associated with an increased incidence of complex VZV infection and contributed to VZV-associated death in children with ALL.

[Effect of Chemotherapy Course Delay on the Relapse of Paediatric B-cell Acute Lymphoblastic Leukemia].

OBJECTIVE: To investigate the effect of course delay of CCLG-ALL-2008 regimen on the relapse of paediatric B-cell acute lymphoblastic leukemia (B-ALL) patients. METHODS: Paediatric B-ALL patients newly diagnosed and treated with CCLG-ALL-2008 regimen in the Children's Hospital of Soochow University from January 2011 to December 2014 were retrospectively analyzed to clarify the relationship between chemotherapy course delay and relapse, and explore the causes of course delay which led to relapse. Patients were followed up until July 2019. RESULTS: The correlation between treatment delay (number of weeks) and relapse rate was statistically significant (P=0.034), and hazard ratio indicated that longer than 4 weeks had a significant effect. The effect of positive minimal residual disease (MRD) (1×10-4≤MRD≤1×10-2) at the 12th week on the relapse rate was also statistically significant (P=0.041). Among the causes of treatment delay, the effect of myelosuppression on the relapse rate was statistically significant (P=0.01). CONCLUSION: Treatment delay exceeding 4 weeks, positive MRD at the 12th week, and myelosuppression are independent prognostic factors for relapse.

The Correlation Between Busulfan Exposure and Clinical Outcomes in Chinese Pediatric Patients: A Population Pharmacokinetic Study.

Aims: The aims of the study were to 1) establish a population pharmacokinetic (Pop-PK) model for busulfan in Chinese pediatric patients undergoing hematopoietic stem cell transplantation (HSCT) and then estimate busulfan exposure and 2) explore the association between busulfan exposure and clinical outcomes. Methods: A total of 128 patients with 467 busulfan concentrations were obtained for Pop-PK modeling using nonlinear mixed effect model (NONMEM) software. Sixty-three patients who received the 16-dose busulfan conditioning regimen were enrolled to explore the correlations between clinical outcomes and the busulfan area under the concentration-time curve (AUC) using the Cox proportional hazards regression model, Kaplan-Meier method and logistic regression. Results: The typical values for clearance (CL) and distribution volume (V) of busulfan were 7.71 L h-1 and 42.4 L, respectively. The allometric normal fat mass (NFM) and maturation function (Fmat) can be used to describe the variability in CL, and the fat-free mass (FFM) can be used to describe the variability in V. Patients with AUCs of 950-1,600 µM × min had 83.7% (95% CI: 73.3-95.5) event-free survival (EFS) compared with 55.0% (95% CI: 37.0-81.8) for patients with low or high exposure (p = 0.024). The logistic regression analysis results showed no association between transplant-related toxicities and the busulfan AUC (p > 0.05). Conclusions: The variability in busulfan CL was related to the NFM and Fmat, while busulfan V was related to the FFM. Preliminary analysis results suggested that a busulfan AUC of 950-1,600 µM × min was associated with better EFS in children receiving the 16-dose busulfan regimen.

[Efficacy of Chimeric Antigen Receptor T Cell in the Treatment of Refractory/Recurrent B Acute Lymphocytic Leukemia in Children].

OBJECTIVE: To observe the efficacy of chimeric antigen receptor T cell (CAR-T) in the treatment of children with refractory/recurrent B acute lymphocytic leukemia (B-ALL). METHODS: Thirty-two patients with r/r B-ALL were treated by CAR-T, the recurrence and death respectively were the end point events to evaluate the efficacy and safety of CAR-T. RESULTS: The median age of the patients was 7.5 (2-17.5) years old; 40 times CAR-T were received in all patients and the median number of CAR-T was 0.9×107/kg; efficacy evaluation showed that 2 cases died before the first evaluation. Thirty patients showed that 3, 6, and 9-moth RFS was (96.3±3.6)%, (81.4±8.6)% and (65.3±12.5)%, respectively, while 3, 6, and 9-month OS was all 100%, and 12, 24-month OS was (94.7±5.1)% and (76±12.8)%. BM blasts≥36% before reinfusion and ferritin peak≥2 500 ng/ml within two weeks of CAR-T cell reinfusion were associated with recurrence. Adverse reactions mainly included cytokine release syndrome (CRS) and CART-cell-related encephalopathy syndrome (CRES), CRS appeared in 26 patients within a week of CAR-T cell reinfusion. CRES reaction was detected in 12 patients. Eighteen patients received intravenous drip of tocilizumab, among them, 12 combined with glucocorticoid. CRS and CRES reactions were relieved within one week after treatment. Hormone dosage was related to the duration of remission in patients, and the cumulative dose of methylprednisolone≥8 mg/kg showed a poor prognosis. CONCLUSION: CAR-T is a safe and effective treatment for r/r B-ALL, most CRS and CRES reactions are reversible. BM blasts ≥36% before reinfusion and cumulative dose of methylprednisolone ≥8 mg/kg after reinfusion both affect the therapeutic effect. Ferritin≥2 500 ng/ml within two weeks after reinfusion is related to disease recurrence and is an independent prognostic risk factor.

Outcomes and risk factors of hemorrhagic cystitis in pediatric allogeneic hematopoietic stem cell transplantation recipients using different graft source and condition with severe aplastic anemia.

BACKGROUND: Hemorrhagic cystitis (HC) is a severe complication of allo-HSCT, characterized by irritative symptoms of the urinary tract and a higher morbidity rate. The risk factors and prognosis of HC are still unclear. OBJECTIVE: The objective of this study is to identify risk factors and outcomes to improve treatment in pediatric SAA patients undergoing HSCTs in the Children's Hospital of Soochow University. METHODS: A total of 97 SAA patients as a cohort were enrolled from 2010 to 2019 in the Children's Hospital of Soochow University and a number of factors related to HC and outcomes were analysed. In all transplants (except UCBT), patients received a combination of G-CSF stimulated bone marrow (BM) and peripheral blood stem cell (PBSC). The minimum number of CD34 + cells is 5 × 106 cells/kg. RESULTS: Mononuclear cells dose (MNC, cut off: 8.53 × 108/kg) and grade II-IV acute graft versus host disease (aGVHD) were identified as independent risk factors for HC. Patients without HC had better overall survival (OS) than with HC (No HC: 98.6%±1.4% vs HC: 87.4% ± 6.8%, p = 0.03). CONCLUSION: We concluded that aGVHD and MNC dose in graft might play an important role in the development of HC in pediatric SAA patients undergoing allo-HSCT. HC is also a key complication affecting the prognosis of children with SAA after allo-HSCT.