Purpose: The survival rate of children with refractory/relapsed acute myeloid leukemia (R/R-AML) by salvage chemotherapy is minimal. Treatment with chimeric antigen receptor T cells (CAR T) has emerged as a novel therapy to improve malignancies treatment. C-type lectin-like molecule 1 (CLL1) is highly expressed on AML stem cells, blast cells, and monocytes, but not on normal hematopoietic stem cells, indicating the therapeutic potential of anti-CLL1 CAR T in AML treatment. This study aimed to test the safety and efficacy of CAR T-cell therapy in R/R-AML. Patients and Methods: Four pediatric patients with R/R-AML were enrolled in the ongoing phase I/II anti-CLL1 CAR T-cell therapy trial. The CAR design was based on an apoptosis-inducing gene, FKBP-caspase 9, to establish a safer CAR (4SCAR) application. Anti-CLL1 CAR was transduced into peripheral blood mononuclear cells of the patients via lentivector 4SCAR, followed by infusion into the recipients after lymphodepletion chemotherapy. Cytokine release syndrome, immune effector cell–associated neurotoxicity syndrome, and other adverse events were documented. Treatment response was evaluated by morphology and flow cytometry–based minimal residual disease assays. Results: Three patients with R/R-AML achieved complete remission and minimal residual disease negativity, while the other patient remained alive for 5 months. All these patients experienced low-grade and manageable adverse events. Conclusions: On the basis of our single-institution experience, autologous anti-CLL1 CAR T-cell therapy has the potential to be a safe and efficient alternative treatment for children with R/R-AML, and therefore requires further investigation.

Background: Though the efficacy of anti C‐type lectin‐like molecule‐1 (CLL1) CAR T‐cells in refractory/relapsed acute myeloid leukemia (R/R‐AML) have been occasionally reported, the influence of co‐stimulatory domain CAR T‐cells is not investigated so far.Method: Seven R/R‐AML children treated with anti‐CLL1 CAR T‐cells were enrolled onto this preliminary comparison study. Among these seven patients, four received CD28/CD27‐based CAR T‐cells therapy, and three received 4‐1BB‐based CAR T‐cells therapy.Result: The overall response rates were 75% and 66.7% in CD28/CD27 and 4‐1BB group respectively. All patients experienced grade 1 to 2 cytokine release syndrome, with only one patient experiencing grade 2 immune effector cell‐associated neurotoxicity syndrome. The maximum CAR T‐cells durations were 156 and 274 days for CD28/CD27 group and 4‐1BB group respectively. The 1‐yr overall survival rate was 57.1%.Conclusions: A preliminary similar efficacy/safety index was observed in anti‐CLL1‐based CAR T‐cells with 4‐1BB or CD28/CD27 co‐stimulatory elements in treating pediatric R/R‐AML.

Secondary acute myeloid leukemia (sAML) is a high-risk AML evolving from heterogenous prior hematological disorders. Compared to de novo AML, sAML has even worse responses to current therapy and thus is associated with lower remission rates, inferior overall survival (OS) and higher relapse rates. Many efforts have been devoted to improving the overall but with limited success, and novel strategy is thus highly needed. Recent research has identified that CLL1 is highly expressed on AML leukemia stem cells and blasts cells but not on normal hematopoietic stem cells. In this case report, we treated a secondary AML patient with anti -CLL1 CAR-T therapy and achieved morphological, immunophenotypic and molecular complete remission for over 10 months. Although only one successful case is presented here, the anti-CLL1 CAR T-cells should be considered as another treatment option for secondary AML in the future.

The discovery of induced pluripotent stem cells(iPSCs) is a promising advancement in the field of regenerative medicine. Previous studies have indicated that the teratoma-forming propensity of iPSCs is variable; however, the relationship between tumorigenic potential and genomic instability in human iPSCs (HiPSCs) remains to be fully elucidated. Here, we evaluated the malignant potential of HiPSCs by using both colony formation assays and tumorigenicity tests. We demonstrated that HiPSCs formed tumorigenic colonies when grown in cancer cell culture medium and produced malignancies in immunodeficient mice. Furthermore, we analyzed genomic instability in HiPSCs using whole-genome copy number variation analysis and determined that the extent of genomic instability was related with both the cells' propensity to form colonies and their potential for tumorigenesis. These findings indicate a risk for potential malignancy of HiPSCs derived from genomic instability and suggest that quality control tests, including comprehensive tumorigenicity assays and genomic integrity validation, should be rigorously executed before the clinical application of HiPSCs. In addition, HiPSCs should be generated through the use of combined factors or other approaches that decrease the likelihood of genomic instability.

PURPOSE: Survivors of childhood cancer often experience treatment-related chronic health conditions. Given its vast population, China shares a large proportion of the global childhood cancer burden. Yet, screening and treatment of late effects in survivors of childhood cancer remain underaddressed in most regions of China. This study aimed to identify high-priority late effects for harmonizing screening guidelines within the Chinese Children's Cancer Group (CCCG), as well as barriers and enablers of the implementation of surveillance recommendations in local practice. METHODS: To establish clinical consensus, 12 expert panelists who represent major institutions within the CCCG completed a Delphi survey and participated in a focus group discussion. The survey solicited ratings of the prevalence, severity, and priority for screening of 45 late effects. Major themes identified from the focus group were analyzed using thematic analysis. RESULTS: The Delphi survey identified eight high-priority late effects for harmonization within CCCG: osteonecrosis, osteoporosis, left ventricular dysfunction, secondary brain tumors, treatment-related myeloid leukemia, gonadal dysfunction, growth hormone deficiency, and neurocognitive deficits. The common barriers to implementing survivorship programs include lack of support and resources for clinicians to provide follow-up care. Patients were also concerned about privacy issues and lacked awareness of late effects. Many institutions also lacked rehabilitation expertise and referral pathways. CONCLUSION: By identifying obstacles related to the professional setting, patient behavior, and organization of care, our study identified resources and a framework for establishing collaborative strategies to facilitate follow-up care of childhood cancer survivors in China.

Cancer immunotherapies exhibit impressive efficacy in some cancers but show only limited benefits for refractory hematological malignancies. The complex immune escape mechanisms of hematological cancers remain unclear. Here, we found that P-selectin glycoprotein ligand 1 (PSGL-1) was highly expressed by hematological cancers and negatively correlated with cancer prognosis. PSGL-1 deficiency in tumors suppressed the progression of multiple mouse models of hematological cancer by promoting infiltration of macrophages and their phagocytic activity. Tumor PSGL-1 inhibited the interaction between tumor ICAM-1 and CD11a/CD18 integrin (LFA-1) in macrophages, thereby suppressing prophagocytic signaling downstream of LFA-1. A humanized antibody targeting human PSGL-1 (αhPSGL-1) efficiently triggered macrophage phagocytosis of human hematological malignancies in vitro and slowed cancer progression in vivo. Additionally, PSGL-1 blockade potentiated the efficacy of doxorubicin chemotherapy and anti-CD47 and anti-CD38 antibody therapy. Therefore, PSGL-1 is a previously undescribed phagocytosis checkpoint, and targeting PSGL-1 could be a promising immunotherapy strategy for treating hematological malignancies.