We present the 16th reported case of Acute Lymphoblastic Leukemia (ALL) with involvement in the bladder. Our patient was a 22 year-old man with T-cell ALL with a mediastinal mass. He received hyperfractionated cyclophos-phamide, vincristine, doxorubicin, dexamethasone (HyperCVAD) with mediastinal radiation. Prior to starting maintenance, he relapsed in the bladder and marrow. He received a nelarabine-based induction regimen and achieved remission. This was followed by an unrelated 11/12 HLA-matched myeloablative allogeneic stem cell transplant. He is in complete remission for the past 409 days.

T cell Acute Lymphoblastic Leukemia/Lymphoma (T-ALL/LBL) is a precursor T cell leukemia/lymphoma that represents approximately 15% of all childhood and 25% of adult acute lymphoblastic leukemia. Although a high cure rate is observed in children, therapy resistance is often observed in adults and mechanisms leading to this resistance remain elusive. Utilizing public gene expression datasets, a fibrotic signature was detected in T-LBL but not T-ALL biopsies. Further, using a T-ALL cell line, CCRF-CEM (CEM) cells, we show that CEM cells induce pulmonary remodeling in immunocompromised mice, suggesting potential interaction between these cells and lung fibroblasts. Co-culture studies suggested that fibroblasts-induced phenotypic and genotypic divergence in co-cultured CEM cells leading to diminished therapeutic responses in vitro. Senescent rather than proliferating stromal cells induced these effects in CEM cells, due, in part, to the enhanced production of oxidative radicals and exosomes containing miRNAs targeting BRCA1 and components of the Mismatch Repair pathway (MMR). Collectively, our studies demonstrate that there may be bidirectional interaction between leukemic cells and stroma, where leukemic cells induce stromal development in vivo and senescent stromal cells generates genomic alterations in the leukemic cells rendering them therapeutic resistant. Thus, targeting senescent stroma might prove beneficial in T-ALL/LBL patients.

Myeloid/natural killer (NK) cell precursor acute leukemia (MNKPL) has been described on the basis of its unique immunophenotype and clinical phenotype. However, there is no consensus on the characteristics for identifying this disease type because of its rarity and lack of defined distinctive molecular characteristics. In this study, multiomics analysis revealed that MNKPL is distinct from acute myeloid leukemia, T cell acute lymphoblastic leukemia, and mixed-phenotype acute leukemia (MPAL), and NOTCH1 and RUNX3 activation and BCL11B down-regulation are hallmarks of MNKPL. Although NK cells have been classically considered to be lymphoid lineage-derived, the results of our single-cell analysis using MNKPL cells suggest that NK cells and myeloid cells share common progenitor cells. Treatment outcomes for MNKPL are unsatisfactory, even when hematopoietic cell transplantation is performed. Multiomics analysis and in vitro drug sensitivity assays revealed increased sensitivity to l-asparaginase and reduced levels of asparagine synthetase (ASNS), supporting the clinically observed effectiveness of l-asparaginase.

Early T-cell precursor leukaemia (ETP-ALL) is a high-risk subtype of human leukaemia that is poorly understood at the molecular level. Here we report translocations targeting the zinc finger E-box-binding transcription factor ZEB2 as a recurrent genetic lesion in immature/ETP-ALL. Using a conditional gain-of-function mouse model, we demonstrate that sustained Zeb2 expression initiates T-cell leukaemia. Moreover, Zeb2-driven mouse leukaemia exhibit some features of the human immature/ETP-ALL gene expression signature, as well as an enhanced leukaemia-initiation potential and activated Janus kinase (JAK)/signal transducers and activators of transcription (STAT) signalling through transcriptional activation of IL7R. This study reveals ZEB2 as an oncogene in the biology of immature/ETP-ALL and paves the way towards pre-clinical studies of novel compounds for the treatment of this aggressive subtype of human T-ALL using our Zeb2-driven mouse model.

Adult acute lymphoblastic leukemia/lymphoma (ALL/LBL) is a rare and heterogeneous malignancy characterized by uncontrolled proliferation of B or T cell precursor cells. Here, we retrospectively analyzed the outcome of early autologous stem cell transplantation in standard-risk patients in first complete remission (n=24) and of allogeneic transplantation in high and highest risk, and relapsed/refractory patients (n=35). The 10-year overall survival after autologous transplantation was 45%. The 10-year overall survival after allogeneic transplantation was 58%. The cumulative incidence of relapse was 29% after allogeneic and 67% after autologous transplantation. The cumulative incidence of non-relapse mortality was 0% after autologous and 12% after allogeneic transplantation. This retrospective single center analysis in a limited number of standard-risk patients clearly demonstrates that early autologous transplantation in first complete remission leads to an acceptable long-term outcome with a short overall treatment duration of less than 6 months compared with more than 2 years with conventional chemotherapy. More sensitive and standardized methods to detect minimal residual disease (MRD) will further help to identify those patients more accurately who are most likely to benefit from such a short and intensive treatment strategy (i.e., MRD negative standard-risk patients) or those who require early targeted therapy (e.g., blinatumomab) in case of MRD positivity. Early allogeneic transplantation results in long-term survival/cure in nearly two-thirds of all high and highest risk, and relapsed/refractory patients.

T cells engineered with chimeric antigen receptor (CAR-T cells) are an effective treatment in patients with relapsed/refractory B-cell precursor acute lymphoblastic leukemia or B-cell non-Hodgkin lymphoma. Despite the reported exciting clinical results, the CAR-T cell approach needs efforts to improve the safety profile, limiting the occurrence of adverse events in patients given this treatment. Besides the most common side effects, such as cytokine release syndrome and CAR-T cell-related encephalopathy syndrome, another potential issue involves the inadvertent transduction of leukemia B cells with the CAR construct during the manufacturing process, thus leading to the possibility of a peculiar mechanism of antigen masking and treatment resistance. In this study, we investigated whether the inclusion of the inducible caspase 9 (iC9) suicide gene in the CAR construct design could be an effective safety switch to control malignant CAR+ B cells, ultimately counteracting this serious adverse event. iC9 is a suicide gene able to be activated through binding with an otherwise inert small biomolecule, known as AP1903. The exposure of iC9.CAR.CD19-DAUDI lymphoma and iC9.CAR.CD19-NALM-6 leukemia cells in vitro to 20 nM of AP1903 resulted into the prompt elimination of CAR+ B-leukemia/lymphoma cell lines. The results obtained in the animal model corroborate in vitro data, since iC9.CAR.CD19+ tumor cells were controlled in vivo by the activation of the suicide gene through administration of AP1903. Altogether, our data indicate that the inclusion of the iC9 suicide gene may result in a safe CAR-T cell product, even when manufacturing starts from biological materials characterized by heavy leukemia blast contamination.