Objectives Leukemia stem cells (LSCs) in chronic myeloid leukemia (CML) are associated with disease recurrence and progression, cannot be eliminated by tyrosine kinase inhibitors (TKIs), and affect TKI discontinuation in CML patients. Chimeric antigen receptor T cells (CAR-T) therapy can eliminate tumor cells expressing specific antigens. CD7 is highly expressed on LSCs and can distinguish LSCs from normal hematopoietic stem cells (HSCs). This study explored the biological characteristics of CD7, and evaluated the effects of CD7 CAR-T cells on CD7+ CML tumor cells and CD7+ LSCs in vitro.Methods We examined CD7 expression in primary CML LSCs, constructed CD7-overexpressing K562 cells, and assessed the in vitro cytotoxicity, degranulation and cytokine secretion of CD7 CAR-T cells against CD7+ CML cells and CD34+CD7+ LSCs, along with the correlation between CD7 and TKI resistance.Results CD7+ CML tumor cells were resistant to TKI to a certain extent. This molecule appears to be relevant to the survival of LSCs in patients with CML receiving TKI-targeted therapy. In the in vitro co-culture system, CD7 CAR-T cells effectively eliminate CD7+ CML cells and LSCs and exhibit multiple immunological activities during the co-culture process.Discussion This study targets the key limitation of current CML treatment in that TKIs fail to eliminate LSCs, and confirms the correlation between CD7 and LSC survival, as well as the targeting potential of CD7 CAR-T for CML.Conclusion This study showed that using CD7 CAR-T cells to specifically eliminate LSCs is effective and rational in vitro, which provides experimental evidence for LSC-targeted CML therapy and lays a foundation for subsequent in vivo and translational research.

Chimeric antigen receptor T (CAR-T) cell therapy targeting T cell tumors still faces many challenges, one of which is its fratricide due to the target gene expressed on CAR-T cells. Despite this, these CAR-T cells can be expanded in vitro by extending the culture time and effectively eliminating malignant T cells. However, the mechanisms underlying CAR-T cell survival in cell subpopulations, the molecules involved, and their regulation are still unknown. We performed single-cell transcriptome profiling to investigate the fratricidal CAR-T products (CD26 CAR-Ts and CD44v6 CAR-Ts) targeting T cells, taking CD19 CAR-Ts targeting B cells from the same donor as a control. Compared with CD19 CAR-Ts, fratricidal CAR-T cells exhibit no unique cell subpopulation, but have more exhausted T cells, fewer cytotoxic T cells, and more T cell receptor (TCR) clonal amplification. Furthermore, we observed that fratricidal CAR-T cell survival was accompanied by target gene expression. Gene expression results suggest that fratricidal CAR-T cells may downregulate their human leukocyte antigen (HLA) molecules to evade T cell recognition. Single-cell regulatory network analysis and suppression experiments revealed that exhaustion mediated by critical regulatory factors may contribute to fratricidal CAR-T cell survival. Together, these data provide valuable and first-time insights into the survival of fratricidal CAR-T cells.

The CACA Guidelines was summarized by Hematology Oncology Committee of China Anti- Cancer Association. This portion of the CACA Guidelines for adult acute myeloid leukemia (AML) not only focuses on diagnosis, the treatment options for younger (age < 60 years) and older (age ≥ 60 years) patients (including non-APL, APL, R/R AML), but also pay attention to the treatment of AML complications, including central nervous system leukemia (CNSL), cardiotoxicity, agranulocytosis and fever, hepatitis B virus reactivation, uric acid nephropathy, bleeding and coagulation disorders, and nursing for patients with AML from the perspective of holistic integrative medicine to enhance the quality of life and treatment effects.

Supplementary Tables 1,4 and Figures.docx Supplementary Table S1: Summary of RNA-seq and smRNA-seq data Supplementary Table S4: The information of cancer related pathways Supplementary Figure S1: Project design and flowchart of the study Supplementary Figure S2: Cluster of differentially expressed genes Supplementary Figure S3: Heatmap of the expression of key TFs and miRNAs in the transformation Supplementary Figure S4: Regulatory network for K562-MVs highly expressed TFs and miRNAs Supplementary Figure S5: Expression of miR-146b-5p in K562-MVs after infection Supplementary Figure S6: Level of NUMB mRNA in the recipient cells when NUMB-lentivirus was transfected

Supplementary Table S2. Summary of gene and miRNA expression by different expression level

Supplementary Table S6. TF and miRNA co-regulatory network for the Cell cycle and DNA repair pathways.

Objective: To evaluate the effectiveness of ruxolitinib on acute graft-versus-host disease (aGVHD) prophylaxis and its impact on graft-versus-leukemia (GVL) effect in patients after modified donor lymphocyte infusion (mDLI). Methods: We retrospectively included patients with relapsed leukemia after allogeneic hematopoietic stem cell transplantation (allo-HSCT) who received ruxolitinib prophylaxis between October 2018 and April 2020. The incidence of aGVHD, disease-free survival (DFS), overall survival (OS), and treatment safety were evaluated. Results: Seventeen patients were followed up for a median time of 8 months (range: 1-26 months). The incidence of aGVHD on Day 30 after mDLI was 41.2% and ranged from Grade 1 to 4; ten of 17 patients (58.8%) achieved a complete response (CR), and two (11.8%) had a partial response (PR). Cytomegalovirus (CMV) reactivation rate was 23.5%, and the median time from mDLI to CMV reactivation was 48.5 days. The mean DFS and OS after mDLI were 1.0 (95% CI 0.0-3.5) and 9.0 (95% CI 1.2-16.8) months, respectively. The causes of death for 10 patients were leukemia relapse (n = 5), aGVHD and septic shock (n = 3), intracranial lesion (n = 1), and COVID-19 (n = 1). Conclusions: We reported encouraging results of ruxolitinib monotherapy in the prevention of aGVHD and maintenance of GVL for post-transplantation relapsed patients, even though being at high risk with poor initial prognosis.

BackgroundCD44v6 chimeric antigen receptor T (CD44v6 CAR-T) cells demonstrate strong anti-tumor ability and safety in acute myeloid leukemia (AML). However, the expression of CD44v6 on T cells leads to transient fratricide and exhaustion of CD44v6 CAR-T cells, which affect the application of CD44v6 CAR-T. The exhaustion and function of T cells and CD44v6 expression of AML cells are associated with DNA methylation. Hypomethylating agents (HAMs) decitabine (Dec) and azacitidine (Aza) have been widely used to treat AML. Therefore, there may be synergy between CD44v6 CAR-T cells and HAMs in the treatment of AML. MethodsCD44v6 CAR-T cells pretreated with Dec or Aza were co-cultured with CD44v6+ AML cells. Dec or aza pretreated AML cells were co-cultured with CD44v6 CAR-T cells. The cytotoxicity, exhaustion, differentiation and transduction efficiency of CAR-T cells, and CD44v6 expression and apoptosis in AML cells were detected by flow cytometry. The subcutaneous tumor models were used to evaluate the anti-tumor effect of CD44v6 CAR-T cells combined with Dec in vivo. The effects of Dec or Aza on gene expression profile of CD44v6 CAR-T cells were analyzed by RNA-seq. ResultsOur results revealed that Dec and Aza improved the function of CD44v6 CAR-T cells through increasing the absolute output of CAR+ cells and persistence, promoting activation and memory phenotype of CD44v6 CAR-T cells, and Dec had a more pronounced effect. Dec and Aza promoted the apoptosis of AML cells, particularly with DNA methyltransferase 3A (DNMT3A) mutation. Dec and Aza also enhanced the CD44v6 CAR-T response to AML by upregulating CD44v6 expression of AML cells regardless of FMS-like tyrosine kinase 3 (FLT3) or DNMT3A mutations. The combination of Dec or Aza pretreated CD44v6 CAR-T with pretreated AML cells demonstrated the most potent anti-tumor ability against AML. ConclusionDec or Aza in combination with CD44v6 CAR-T cells is a promising combination therapy for AML patients.

Chimeric antigen receptor T-cell (CAR-T-cell) therapy has been well researched to date because of its ability to target malignant tumor cells. The most common CAR-T cells are CD19 CAR-T cells, which play a large role in B-cell leukemia treatment. However, most CAR-T cells are associated with relapse after clinical treatment, so the quality and persistence of CAR-T cells need to be improved. With continuous optimization, there have been four generations of CARs and each generation of CARs has better quality and durability than the previous generation. In addition, it is important to increase the proportion of memory cells in CAR-T cells. Studies have shown that an immunosuppressive tumor microenvironment (TME) can lead to dysfunction of CAR-T cells, resulting in decreased cell proliferation and poor persistence. Thus, overcoming the challenges of immunosuppressive molecules and targeting cytokines in the TME can also improve CAR-T cell persistence. In this paper, we explored how to improve the durability of CAR-T cell therapy by improving the structure of CARs, increasing the proportion of memory CAR-T cells and improving the TME.

BACKGROUND:Multiple targets of chimeric antigen receptor T cells (CAR-T cells) are shared expressed by tumor cells and T cells, these self-antigens may stimulate CAR-T cells continuously during the expansion. Persistent exposure to antigens is considered to cause metabolic reprogramming of T cells and the metabolic profiling is critical in determining the cell fate and effector function of CAR-T cells. However, whether the stimulation of self-antigens during CAR-T cell generation could remodel the metabolic profiling is unclear. In this study, we aim to investigate the metabolic characteristics of CD26 CAR-T cells, which expressed CD26 antigens themselves.METHODS:The mitochondrial biogenesis of CD26 and CD19 CAR-T cells during expansion was evaluated by the mitochondrial content, mitochondrial DNA copy numbers and genes involved in mitochondrial regulation. The metabolic profiling was investigated by the ATP production, mitochondrial quality and the expression of metabolism-related genes. Furthermore, we assessed the phenotypes of CAR-T cells through memory-related markers.RESULTS:We reported that CD26 CAR-T cells had elevated mitochondrial biogenesis, ATP production and oxidative phosphorylation at early expansion stage. However, the mitochondrial biogenesis, mitochondrial quality, oxidative phosphorylation and glycolytic activity were all weakened at later expansion stage. On the contrary, CD19 CAR-T cells did not exhibit such characteristics.CONCLUSION:CD26 CAR-T cells showed distinctive metabolic profiling during expansion that was extremely unfavorable to cell persistence and function. These findings may provide new insights for the optimization of CD26 CAR-T cells in terms of metabolism.

Supplementary methods for sequencing, regular data analysis and routine experimental methods including primer sequences.

Supplementary Table S5. GO enrichment for 8 cluters of DEGs

Chimeric antigen receptor T cell (CAR-T) therapy in hematologic malignancies has made great progress, but there are still some problems. First, T cells from tumor patients show an exhaustion phenotype; thus, the persistence and function of the CAR-Ts are poor, and achieving a satisfactory curative effect is difficult. Second, some patients initially respond well but quickly develop antigen-negative tumor recurrence. Thirdly, CAR-T treatment is not effective in some patients and is accompanied by severe side effects, such as cytokine release syndrome (CRS) and neurotoxicity. The solution to these problems is to reduce the toxicity and enhance the efficacy of CAR-T therapy. In this paper, we describe various strategies for reducing the toxicity and enhancing the efficacy of CAR-T therapy in hematological malignancies. In the first section, strategies for modifying CAR-Ts using gene-editing technologies or combining them with other anti-tumor drugs to enhance the efficacy of CAR-T therapy are introduced. The second section describes some methods in which the design and construction of CAR-Ts differ from the conventional process. The aim of these methods is to enhance the anti-tumor activity of CAR-Ts and prevent tumor recurrence. The third section describes modifying the CAR structure or installing safety switches to radically reduce CAR-T toxicity or regulating inflammatory cytokines to control the symptoms of CAR-T-associated toxicity. Together, the knowledge summarized herein will aid in designing better-suited and safer CAR-T treatment strategies.

Exosomes are membrane limited structures which derive from cell membranes and cytoplasm. When released into extracellular space, they circulate through the extracellular fluid, including the peripheral blood and tissue fluid. Exosomes surface molecules mediate their targeting to specific recipient cells and deliver their contents to recipient cells by receptor-ligand interaction and/or phagocytosis and/or endocytosis or direct fusion with cell membrane. Exosomes contain many functional molecules, including nucleic acids (DNAs, mRNAs, non-coding RNAs), proteins (transcription factors, enzymes), and lipids which have biological activity. By passing these cargos, exosomes can transfer information between cells. In this way, exosomes are extensively involved in physiological and pathological processes, such as angiogenesis, matrix reprogramming, coagulation, tumor progression. In recent years, researcher have found that exosomes from malignant tumors can mediate information exchange between tumor cells or between tumor cells and non-tumor cells, thereby promoting tumor survival, progression, and resistance to therapy. In this review, we discuss the pro-tumor and anti-therapeutic effects of exosomes in hematological malignancies, hoping to contribute to the early conquest of hematological malignancy.

Background:To curb the spread of the coronavirus disease 2019 (COVID-19) epidemic, the Chinese government shut down Wuhan city from January 23rd to April 8th, 2020. The COVID-19 epidemic not only leads to widespread illness but also affects the diagnosis and treatment of hematopoietic stem-cell transplant (HSCT) recipients.Objective:To investigate the medical-seeking pattern and daily behavior changes in Hubei Province during the COVID-19 epidemic in Hubei Province during the lockdown.Methods:We conducted a multicenter, cross-sectional, web-based investigation among 325 HSCT recipients by online questionnaires in Hubei Province during the COVID-19 epidemic.Results:A total of 145 complete responses were collected both before and during the epidemic questionnaires. The participants from pre-epidemic group preferred to go to hospital (68.29%) when they experienced influenza-like symptoms. The majority of the patients elected to take oral drugs by themselves (40%) or consulted their attending physicians online or by telephone during the lockdown (23.33%). 64.83% had difficulties in purchasing drugs during the lockdown, which was significantly higher than the proportion of the pre-epidemic group (24.83%) (P < 0.05). The participants preferred to purchase drugs online (23.40%) and decrease or withdraw drugs (18.09%) during the epidemic. The number of participants received regular re-examinations during the epidemic decreased sharply. The proportion of wearing masks and isolating themselves at home increased significantly during the epidemic. No statistic difference was observed in the incidence of graft-versus-host disease (GVHD)complications in participants between the during the epidemic group and the pre-epidemic group. In our study, six patients were confirmed to have COVID-19, and half of them died due to COVID-19-related complications.Conclusion:The medical-seeking pattern and daily behavior of HSCT recipients changed during the lockdown; the methods of self-protection, online consultation and drug delivery can help patients receive necessary follow-up and reduce the occurrence of COVID-19.

The optimal conditioning regimen for high-risk myelodysplastic syndrome (MDS) patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains elusive. This study aimed to explore the anti-leukemic efficacy and toxicity of Decitabine (Dec, 20 mg/m2/day, day −11 to −7) intensified BUCY2 vs. traditional regimen in high-risk MDS population. We retrospectively evaluated 93 consecutive high-risk MDS patients undergoing allo-HSCT in our institution, comparing discrepancies in clinical characteristics and outcomes between cases using Dec-intensified BUCY2 (n = 52) and traditional BUCY2 regimen (n = 41). Three-year cumulative incidence of relapse after Dec-intensified BUCY2 conditioning was remarkably lower than that of patients using BUCY2 regimen (20.2% vs. 39.0%, p = 0.034). Overall survival and disease-free survival at 3 years for Dec-intensified BUCY2 group were 70.2% and 64.9%, respectively, which were significantly improved when compared with BUCY2 group (51.1% and 43.9%, p = 0.031 and p = 0.027). Furthermore, overall survival and disease-free survival for MDS cases receiving cytoreduction therapy were dramatically better than patients in non-cytoreduction group (p = 0.041, p = 0.047). In summary, the Dec-intensified conditioning regimen could be effective and feasible, providing prominent recurrence control with moderate toxicity for high-risk MDS patients. These patients might also benefit from pre-transplant cytoreductive therapeutic schedules. Larger randomized controlled trials are still needed to further confirm these conclusions.

Haploidentical stem cell transplantation (HSCT) has become an alternative treatment option for patients with aplastic anemia (AA) without matched sibling donors or matched unrelated donors. Recently, post-transplantation cyclophosphamide (PTCy) and granulocyte colony-stimulating factor (G-CSF)/antithymocyte globulin (ATG) regimens have become the most common protocols used worldwide. In this retrospective study, we retrospectively reviewed and analyzed the clinical data of 130 AA patients who underwent haploidentical HSCT and received the modified PTCy (mPTCy) regimen (n = 55) or G-CSF/ATG regimen (n = 75) between January 2013 and June 2021 across 7 transplantation centers. Neutrophil engraftment was successful in all patients within 30 days in the G-CSF/ATG group. The cumulative neutrophil engraftment rate in the mPTCy group was 96.36% (95% confidence interval [CI], 94.57 to 97.57; P = .010). The median time to neutrophil engraftment in the G-CSF/ATG group was 10 days (range, 7 to 28 days), which was more rapid than that observed in the mPTCy group (P < .001). There was no significant difference in the incidence of graft-versus-host disease (GVHD) between the 2 groups. The cumulative incidence of grade II-IV acute GVHD was 18.40% (95% CI, 4.27% to 40.31%) in the mPTCy group and 19.32% (95% CI, 5.86% to 38.58%) in the G-CSF/ATG group, whereas the cumulative incidence of grade III-IV acute GVHD was 7.31% (95% CI,.09% to 37.48%) in the mPTCy group and 7.57% (95% CI, .20 to 34.19) in the G-CSF/ATG group. Similarly, there were no significant between-group differences in overall survival (OS), failure-free survival (FFS), and GVHD-free relapse-free survival (GRFS). The 2-year OS, FFS, and GRFS rates were 95.91% (95% CI, 84.59% to 98.96%), 92.25% (95% CI, 80.59% to 97.03%), and 86.68% (95% CI, 73.98% to 93.44%), respectively, in the mPTCy group and 86.67% (95% CI, 76.64% to 92.59%), 81.28% (95% CI, 70.45% to 88.46%), and 77.20% (95% CI, 65.89% to 85.16%), respectively, in the G-CSF/ATG group. Transplantation-related mortality (TRM) was significantly higher in the G-CSG/ATG group than in them PTCy group (13.33% versus 1.96%; P = .022). In multivariate analysis, the use of a female donor, a higher Hematopoietic Cell Transplantation Comorbidity Index, and grade III-IV acute GVHD were associated with worse survival outcomes. The mPTCy and G-CSF/ATG regimens led to similar outcomes in AA patients, but quicker engraftment was observed with the ATG/G-CSF regimen, and a lower incidence of TRM was observed with the mPTCy regimen. (C) 2022 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Acute myeloid leukemia (AML) patients who develop hematological relapse (HR) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) generally have dismal clinical outcomes. Measurable residual disease (MRD)-directed preemptive interventions are effective approaches to prevent disease progression and improve prognosis for molecular relapsed patients with warning signs of impending HR. In this situation, boosting the graft-vs-leukemia (GVL) effect with immune checkpoint inhibitors (ICIs) might be a promising prevention strategy, despite the potential for causing severe graft-vs-host disease (GVHD). In the present study, we reported for the first time an AML patient with RUNX1-RUNX1T1 who underwent preemptive treatment with the combined application of tislelizumab (an anti-PD-1 antibody) and azacitidine to avoid HR following allo-HSCT. On day +81, molecular relapse with MRD depicted by RUNX1-RUN1T1 -positivity as well as mixed donor chimerism occurred in the patient. On day +95, with no signs of GVHD and an excellent eastern cooperative oncology group performance status (ECOG PS), the patient thus was administered with 100 mg of tislelizumab on day 1 and 100 mg of azacitidine on days 1-7. After the combination therapy, complete remission was successfully achieved with significant improvement in hematologic response, and the MRD marker RUNX1-RUNX1T1 turned negative, along with a complete donor chimerism in bone marrow. Meanwhile, the patient experienced moderate GVHD and immune-related adverse events (irAEs), successively involving the lung, liver, lower digestive tract and urinary system, which were well controlled by immunosuppressive therapies. As far as we know, this case is the first one to report the use of tislelizumab in combination with azacitidine to prevent post-transplant relapse in AML. In summary, the application of ICIs in MRD positive patients might be an attractive strategy for immune modulation in the future to reduce the incidence of HR in the post-transplant setting, but safer clinical application schedules need to be explored.

The application of intracellular and extracellular Epstein–Barr virus (EBV) DNA in allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been poorly characterized. We conducted a combined prospective-retrospective study of 300 patients who underwent allo-HSCT between 2016 to 2019 in our center and monitored for EBV DNA within the first year after HSCT. Combining the optimal cut-off value of EBV DNA load (7.3×10 4 copies/10 6 cells) in peripheral blood mononuclear cells (PBMCs) and qualitative detection in plasma (400 copies/mL) allowed for the better differentiation of EBV-related posttransplant lymphoproliferative disorders (EBV-PTLD), with increased sensitivity (100%) and specificity (86%), and provided the effective risk stratification of EBV DNA level according to their impact on transplant outcomes. By multivariate analysis, patients with intermediate-level of EBV DNA load (low EBV DNA load in PBMCs or high load in PBMCs but negative in plasma) was associated with superior overall survival (HR 1.92, 95% CI 1.03-3.57, p =0.039) and lower transplant-related mortality (HR 3.35, 95% CI 1.31-8.58, p =0.012) compared to those with high-level (high load in PBMCs and positive in plasma). Notably, high EBV-level group had poor reconstitution of CD4+ and CD8+T cells, and both low and high EBV-level groups showed abnormally increase in IL-10 level within one year. Additionally, patients with peak EBV DNA load in PBMCs during 3-12 months had a higher incidence of chronic graft versus host disease (GVHD) than those within 3 months post transplantation (17.4% vs 13.7%, p =0.029). Collectively, EBV DNA in PBMCs can synergistically predict the risk of EBV-PTLD and GVHD. The intermediate-level of EBV DNA presented in plasma and PBMCs might contribute to a better reconstitution of T cells associated with favorable prognosis of allo-HSCT.