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T-cell acute lymphoblastic leukemia (T-ALL) has a dismal prognosis in case of relapsed or refractory disease. Contrary to B-ALL, few immunotherapies are available for T-ALL. Use of autologous CAR T-cells is challenging due to shared antigen between leukemic and normal T-cells responsible for fratricide and T-cell aplasia in case of persistence of CAR T-cells. Moreover, risk of contamination of the apheresis product by lymphoblasts remains an issue. To counteract these challenges several methods are used to edit T-cell such as protein expression blocker, CRISPR/Cas9 and base-editing. Other possibility is to use autologous T-cells naturally selected in vitro or donor-derived T-cells allowing gene edition and reduction of the risk of graft vs host disease. Encouraging results are obtained in preclinical and clinical studies for early response rate but several questions remain. Is the persistence of these cells requiring for maintaining the remission? Is it feasible to recover a target-negative T-cell population without risk of profound immunosuppression? Has an allogeneic stem cell transplantation to be planned for patients after CAR T-cells infusion? What about the risk of engineered T-cells in the long term?

Abstract The reintegration of excised signal joints resulting from human V(D)J recombination was described as a potent source of genomic instability in human lymphoid cancers. However, such molecular events have not been recurrently reported in clinical patient lymphoma/leukemia samples. Using a specifically designed NGS-capture pipeline, we here demonstrated the reintegration of T-cell receptor excision circles (TRECs) in 20/1533 (1.3%) patients with T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lymphoblastic lymphoma (T-LBL). Remarkably, the reintegration of TREC recurrently targeted the tumor suppressor gene, ZFP36L2, in 17/20 samples. Thus, our data identified a new and hardly detectable mechanism of gene deregulation in lymphoid cancers providing new insights in human oncogenesis.

Juvenile myelomonocytic leukemia (JMML) is an aggressive pediatric myeloproliferative neoplasm requiring hematopoietic stem cell transplantation (HSCT) in most cases. We retrospectively analyzed 119 JMML patients who underwent first allogeneic HSCT between 2002 and 2021. The majority (97%) carried a RAS-pathway mutation, and 62% exhibited karyotypic alterations or additional mutations in SETBP1, ASXL1, JAK3 and/or the RAS pathway. Relapse was the primary cause of death, with a 5-year cumulative incidence of 24.6% (95%CI: 17.1-32.9). Toxic deaths occurred in 12 patients, resulting in treatmentrelated mortality (TRM) of 9.0% (95%CI: 4.6-15.3). The 5-year overall (OS) and event-free survival were 73.6% (95%CI: 65.7-82.4) and 66.4% (95%CI: 58.2-75.8), respectively. Four independent adverse prognostic factors for OS were identified: age at diagnosis >2 years, time from diagnosis to HSCT >6 months, monocyte count at diagnosis >7.2x109/L, and the presence of additional genetic alterations. Based on these factors, we proposed a predictive classifier. Patients with three or more predictors (21% of the cohort) had a 5-year OS of 34.2%, whereas those with none (7%) had a 5-year OS of 100%. Our study demonstrates improved transplant outcomes compared to prior published data, which can be attributed to the synergistic impacts of a low TRM and a reduced yet still substantial relapse incidence. By integrating genetic information with clinical and hematological features, we have devised a predictive classifier. This classifier effectively identifies a subgroup of patients who are at a heightened risk of unfavorable post-transplant outcomes who would benefit novel therapeutic agents and post-transplant strategies.

Abstract Background To investigate the educational outcomes of siblings of childhood leukemia survivors, explore determinants of school difficulties, and compare the rates of repeating grades between siblings and the general population. Methods A cross‐sectional study of childhood leukemia survivors' siblings recruited through the Leucémies de l'Enfant et de l'Adolescent cohort, a French long‐term follow‐up program, was conducted, and education‐related data were obtained via self‐report questionnaires. Adjusted logistic regression models were used to identify variables associated with school difficulties and time since diagnosis. Rates of repeating a grade in middle school were compared between siblings and the general population of the same generation. Results A total of 564 siblings with a mean time from diagnosis of 14.1 ± 6.4 years were included, among whom 139 (24.6%) repeated a grade, at an average of 6.4 ± 4.5 years after diagnosis. In multivariate analysis, the risk factors for repeating a grade were older siblings (odds ratio [OR] 2.3, p = 0.006), family financial difficulties (OR 2.8, p = 0.008), and history of repetition in survivors (OR, 2.5, p = 0.001). Sibling hematopoietic stem cell donors were at greater risk of repeating a grade long‐term after diagnosis (p = 0.018). Overall, siblings did not have a higher risk of educational delays at the end of middle school than the general population. Conclusion Although the results are reassuring, socioeconomic and cancer‐related factors may have an impact on siblings' schooling long after diagnosis. Paying attention to siblings contributes to identifying the most vulnerable families, allowing more attention and appropriate resources to avoid long‐term repercussions. Additionally, supportive and targeted interventions can be developed to improve the organization of education and the health care system.

Abstract Background It is difficult to predict the reproductive capacity of children given hematopoietic cell transplantation (HCT) before pubertal age because the plasma concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are not informative and no spermogram can be done. Methods We classified the gonadal function of 38 boys and 34 girls given HCT during childhood who had reached pubertal age according to their pubertal development and FSH and LH and compared this to their plasma inhibin B and anti-Müllerian hormone (AMH). Results Ten (26%) boys had normal testicular function, 16 (42%) had isolated tubular failure and 12 (32%) also had Leydig cell failure. All 16 boys given melphalan had tubular failure. AMH were normal in 25 patients and decreased in 6, all of whom had increased FSH and low inhibin B. Seven (21%) girls had normal ovarian function, 11 (32%) had partial and 16 (47%) complete ovarian failure. 7/8 girls given busulfan had increased FSH and LH and 7/8 had low inhibin B. AMH indicated that ovarian function was impaired in all girls. FSH and inhibin B were negatively correlated in boys (P < 0.0001) and girls (P = 0.0006). Neither the age at HCT nor the interval between HCT and evaluation influenced gonadal function. Conclusion The concordance between FSH and inhibin B suggests that inhibin B may help in counselling at pubertal age. In boys, AMH were difficult to use as they normally decrease when testosterone increases at puberty. In girls, low AMH suggest that there is major loss of primordial follicles.

Abstract Background Childhood cancer confront the whole family with a traumatic event. Because brothers and sisters may encounter emotional problems that can remain for a long time and that only few studies have assessed their long‐term outcome, our present objectives were to describe the long‐term quality of life (QoL) of childhood leukemia survivors' siblings and to explore its determinant. Methods Brothers and sisters (from 8‐year‐old) of survivors included in the French LEA Cohort completed a QoL questionnaire (according to their age). Scores were compared with those reported by age‐ and gender‐matched French general population and by survivors. Using a clustering method, siblings were categorized into 3 groups depending on their level of QoL's scores and factors likely to be linked with these clusters were explored with multivariate analyses. Results We included 689 brothers and sisters (313 minors, 376 adults) and the mean time from diagnosis was 13.2 ± 6.6 years. Minor siblings reported higher QoL scores than general population (p

Abstract Background We explored the heterogeneity of philadelphia chromosome-positive acute lymphoblastic leukemia (Ph1-ALL) in a study of the effect of early features on prognosis in children. Here we report the long-term results of the FRALLE 93 study conducted in the era before the use of tyrosine kinase inhibitors. Methods Between 1993 and 1999, 36 children with Ph1-ALL were enrolled into the FRALLE 93 protocol. After conventional four-drug induction, children were stratified by availability of an HLA-matched sibling. Results Complete remission (CR) was observed in 26 children (72%), of which 13 underwent allogeneic bone marrow transplantation (BMT). Thirty-one children were good responders to prednisone, defined on day 8, and 21 were good responders to chemotherapy, defined by day-21 bone marrow (M1). Overall five-year disease-free survival (DFS) was 42 ± 9.7%. Based on multivariate analysis, two groups showed marked differences in five-year outcome: children with age3 and day-21 M1 marrow had a more favorable prognosis (14 pts: 100% CR, event free survival [EFS]: 57%, overall survival [OS]: 79%), than the high-risk group (22 patients: 55% CR, EFS: 18%, OS: 27%) (p < 0.005). We also observed a non statistically significant difference (p = 0.14) in outcome between these groups for transplanted patients (5-year DFS: 83 ± 14% and 33 ± 15%, respectively). Conclusion Age, leukocyte count and early response to treatment defined by the D21 bone marrow response provide an accurate model for outcome prediction. The combination of available tools such as minimal residual disease assessment with determination of these simple factors could be useful for refining indications for BMT in the current era of tyrosine-kinase inhibitor-based therapy.

Abstract Background Gemtuzumab ozogamicin (GO) is a cytotoxic anti-CD33 monoclonal antibody that has given promising preliminary results in adult myeloid CD33+ AML. We conducted a retrospective multicenter study of 12 children treated with GO on a compassionate basis (median age 5.5 y). Three patients (2 MDS/AML, 1 JMML) were refractory to first-line treatment, 8 patients with de novo AML were in refractory first relapse, and one patient with de novo AML was in 2nd relapse after stem cell transplantation (SCT). CD33 expression exceeded 20% in all cases. Methods GO was administered alone, at a unit dose of 3–9 mg/m2, once (3 patients), twice (3 patients), three (5 patients) or five times (1 patient). Mean follow-up was 128 days (8–585 d). Results There were three complete responses (25%) leading to further curative treatment (SCT). Treatment failed in the other nine patients, and only one patient was alive at the end of follow-up. NCI-CTC grade III/IV adverse events comprised hematological toxicity (n = 12), hypertransaminasemia (n = 2), allergy and hyperbilirubinemia (1 case each). There was only one major adverse event (grade IV allergy). No case of sinusoidal obstruction syndrome occurred. Conclusion These results warrant a prospective trial of GO in a larger population of children with AML.

Abstract The acquisition of genetic abnormalities engendering oncogene dysregulation underpins cancer development. Certain proto-oncogenes possess several dysregulation mechanisms, yet how each mechanism impacts clinical outcome is unclear. Using T-cell acute lymphoblastic leukemia (T-ALL) as an example, we show that patients harboring 5’super-enhancer (5’SE) mutations of the TAL1 oncogene identifies a specific patient subgroup with poor prognosis irrespective of the level of oncogene dysregulation. Remarkably, the MYB dependent oncogenic 5’SE can be targeted using Mebendazole to induce MYB protein degradation and T-ALL cell death. Of note Mebendazole treatment demonstrated efficacy in vivo in T-ALL preclinical models. Our work provides proof of concept that within a specific oncogene driven cancer, the mechanism of oncogene dysregulation rather than the oncogene itself can identify clinically distinct patient subgroups and pave the way for future super-enhancer targeting therapy.

Children with Down syndrome (DS, trisomy 21) are at a significantly higher risk of developing acute leukemia compared to the overall population. Many studies investigating the link between trisomy 21 and leukemia initiation and progression have been conducted over the last two decades. Despite improved treatment regimens and significant progress in iden - tifying genes on chromosome 21 and the mechanisms by which they drive leukemogenesis, there is still much that is unknown. A focused group of scientists and clinicians with expertise in leukemia and DS met in October 2022 at the Jérôme Lejeune Foundation in Paris, France for the 1st International Symposium on Down Syndrome and Leukemia. This meeting was held to discuss the most recent advances in treatment regimens and the biology underlying the initiation, progression, and relapse of acute lymphoblastic leukemia and acute myeloid leukemia in children with DS. This review provides a summary of what is known in the field, challenges in the management of DS patients with leukemia, and key questions in the field.

Abstract Background CAR-T cell (chimeric antigen receptor T) therapy has emerged as an effective treatment of refractory hematological malignancies. Intensive care management is intrinsic to CAR-T cell therapy. We aim to describe and to assess outcomes in critically ill CAR-T cell recipients. Study design and methods Hospital-wide retrospective study. Consecutive CAR-T cell recipients requiring ICU admission from July 2017 and December 2020 were included. Results 71 patients (median age 60 years [37–68]) were admitted to the ICU 6 days [4–7] after CAR-T cell infusion. Underlying malignancies included diffuse large B cell lymphoma (n = 53, 75%), acute lymphoblastic leukemia (17 patients, 24%) and multiple myeloma (n = 1, 1.45%). Performance status (PS) was 1 [1–2]. Shock was the main reason for ICU admission (n = 40, 48%). Isolated cytokine release syndrome (CRS) was the most common complication (n = 33, 46%), while 21 patients (30%) had microbiologically documented bacterial infection (chiefly catheter-related infection). Immune effector cell-associated neurotoxicity syndrome was reported in 26 (37%) patients. At ICU admission, vasopressors were required in 18 patients (25%) and invasive mechanical ventilation in two. Overall, 49 (69%) and 40 patients (56%) received tocilizumab or steroids, respectively. Determinant of mortality were the reason for ICU admission (disease progression vs. sepsis or CRS (HR 4.02 [95%CI 1.10–14.65]), Performance status (HR 1.97/point [95%CI 1.14–3.41]) and SOFA score (HR 1.16/point [95%CI 1.01–1.33]). Conclusions Meaningful survival could be achieved in up to half the CAR-T cell recipients. The severity of organ dysfunction is a major determinant of death, especially in patients with altered performance status or disease progression.

The article discusses the outcomes of infants with very late relapse of acute lymphoblastic leukaemia initially treated in Interfant-06. It highlights the characteristics and outcomes of six children who experienced a very late relapse of infant ALL, providing detailed information on their initial diagnosis, relapse, treatment, and follow-up. The study shows that all patients achieved a second complete remission after a lymphoid-style salvage regimen, with five patients receiving allogeneic hematopoietic stem cell transplantation and experiencing promising long-term results. The findings suggest that infants with very late relapses may have a more favorable outcome compared to those who relapse within the first year after diagnosis, emphasizing the importance of effective first-line therapies in reducing relapse rates. [Extracted from the article]