Genomic imbalances analysis provides new insight into prognostic factors in adult and pediatric T-ALL

Given the poor outcome of refractory and relapsing T-ALL, identifying prognostic markers is still challenging. Using SNP-array analysis, we provide a comprehensive analysis of genomic imbalances in a cohort of 317 newly-diagnosed T-ALL patients including 135 children and 182 adults with respect to clinical and biological features and outcomes. SNP-array results identified at least one somatic genomic imbalance in virtually all T-ALL patients (~96%). Del(9)(p21) (~70%) and UPD(9)p21)/CDKN2A/B (~28%) were the most frequent genomic imbalances. Unexpectedly del(13q14)/RB1/DLEU1 (~14%) was the second more frequent CNV followed by del(6)(q15)/CASP8AP2 (~11%), del(1)(p33)/SIL-TAL1 (~11%), del(12)(p13)ETV6/CDKN1B (~9%), del(18)(p11)/PTPN2 (~9%), del(1)(p36)/RPL22 (~9%), and del(17)(q11)/NF1/SUZ12 (~8%). SNP-array also revealed distinct profiles of genomic imbalances according to age, immunophenotype, and oncogenetic subgroups. In particular, adult T-ALL patients demonstrated a significantly higher incidence of del(1)(p36)/RPL22, and del(13)(q14)/RB1/DLEU1, and lower incidence of del(9)(p21) and UPD(9p21)/CDKN2A/B. We determined a threshold of 15 genomic imbalances to stratify patients into high- and low-risk groups of relapse. Survival analysis also revealed the poor outcome, despite the low number of affected cases, conferred by the presence of chromothripsis (n=6, ~2%), del(16)(p13)/CREBBP (n=15, ~5%) as well as the newly identified recurrent gain at 6q27 involving MLLT4 (n=10, ~3%). Genomic complexity, del(16)(p13)/CREBBP and gain at 6q27 involving MLLT4 maintained their significance in multivariate analysis for survival outcome. Our study thus demonstrated that whole genome analysis of imbalances provides new insights to refine risk stratification in T-ALL.

A predictive classifier of poor prognosis in transplanted patients with juvenile myelomonocytic leukemia: a study on behalf of the Société Francophone de Greffe de Moelle et de Thérapie Cellulaire

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.

Educational outcomes in siblings of childhood leukemia survivors: Factors associated with school difficulties and comparison with general population

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.

Patient-Level Meta-analysis of Clofarabine in Acute Lymphoblastic Leukemia

INTRODUCTION

Clofarabine monotherapy at a dose of 52 mg/m2 per day was approved in the USA in 2004 for the treatment of relapsed or refractory acute lymphoblastic leukemia (R/R ALL) in patients aged 1-21 years after at least two prior regimens. To address a post-marketing requirement for additional evidence of the clinical benefit of clofarabine in its approved indication, a meta-analysis of patient-level data was conducted.

METHODS

A systematic literature review was conducted, using the Dr.Evidence software platform, DOC Search, and Embase, to identify clinical trials with patients with R/R ALL who received clofarabine monotherapy at 52 mg/m2. The primary endpoint was complete remission (CR). Secondary endpoints were overall remission (OR, defined by CR or CR with either incomplete platelet recovery or incomplete neutrophil and platelet recovery), duration of response, overall survival (OS), and safety.

RESULTS

A total of 754 patients in 12 clinical studies were analyzed including 682 patients with R/R ALL treated with clofarabine monotherapy at 52 mg/m2; of them, 374 were aged < 22 years (pediatric population). Rates of CR and OR were 16% (95% confidence interval [CI] 7, 26) and 28% (95% CI 20, 37), respectively, in the pediatric population and 12% (95% CI 5, 21) and 21% (95% CI 13, 31) in the overall population. Median OS (evaluable in three studies in pediatric patients) was 3.7 months (95% CI 0.1, 31.4), reaching 10.1 months (95% CI 0.3, 68.9) for those achieving OR. Sensitivity analyses supported these findings. The most frequent grade 3-4 adverse events were liver abnormalities, anemia, diarrhea, and febrile neutropenia.

CONCLUSION

In this meta-analysis, CR duration and median OS in pediatric patients with R/R ALL appeared to be slightly longer than in the phase II study. No new safety signals were identified. Results support the use of clofarabine monotherapy in its approved indication.

INSPIRED Symposium Part 2: Prevention and Management of Relapse Following Chimeric Antigen Receptor T Cell Therapy for B Cell Acute Lymphoblastic Leukemia

Although CD19-directed chimeric antigen receptor (CAR) T cell therapy (CAR-T) for relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL) has been transformative in inducing and sustaining remission, relapse rates remain unacceptably high, with approximately 50% of children and young adults experiencing relapse within the first year postinfusion. Emerging strategies to extend the durability of remission involve the use of prognostic biomarkers to identify those at high risk of relapse or incorporate strategies aimed to enhancing functional CAR T cell persistence. Nonetheless, with antigen loss/down-regulation or evolution to lineage switch as major mechanisms of relapse, optimizing single antigen targeting alone is insufficient. Here, with a focus on relapse prevention strategies, including postinfusion surveillance and treatment approaches being explored to optimize post-CAR-T management (eg, combinatorial antigen targeting strategies, preemptive hematopoietic cell transplantation), we review the current state of the art in the prevention and management of post CAR-T relapse. We highlight the advancements in the field and identify gaps in the literature to guide future research in optimizing the prevention and management of post-CAR-T relapse in children and young adults with B-ALL.

Down syndrome and leukemia: from basic mechanisms to clinical advances

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.

TREC mediated oncogenesis in human immature T lymphoid malignancies preferentially involves ZFP36L2

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.

Impact of childhood leukemia on siblings: their long-term perception of family functioning and its relationship with their psychosocial characteristics using structural equation modeling

PURPOSE

In the context of pediatric cancer, siblings' adaptation and needs have been previously investigated; however, research on the long-term consequences on siblings, especially on their family environment, is scarce. We aimed to (1) assess the family functioning (FF) perceived by siblings of childhood leukemia survivors long after diagnosis and (2) explore characteristics likely associated and investigate associations with psycho-behavioral and social factors.

METHODS

Childhood leukemia survivors' siblings older than 11 years were recruited through the LEA cohort, a French long-term follow-up program, and completed the family assessment device (FAD). Logistic regression analysis was used to determine factors likely associated with unhealthy functioning in families as perceived by siblings. Structural equation modeling (SEM) was used to examine relationships that predict siblings' perception of FF.

RESULTS

We included 605 siblings (mean follow-up time from diagnosis 14.1 ± 6.8 years), of whom 175 (28.9%) perceived unhealthy functioning. SEM showed that older siblings were more likely to perceive problematic functioning (β = 0.095, p = 0.014). Sex and leukemia burden had indirect effects on FF through mediators. Family financial situation at diagnosis was not associated with the risk of reporting unhealthy functioning.

CONCLUSIONS

Our study contributed to identifying siblings at risk of facing family issues and reinforced the need to provide more consideration and suitable resources to avoid late consequences. Often considered as the "forgotten children", future research should focus on developing targeted interventions to facilitate family communication and improve siblings' social support.

IMPLICATIONS FOR CANCER SURVIVORS

Overall, results regarding FF perceived by siblings are reassuring and provide new enlightening elements that allow for better support to all families.

Hematopoietic stem cell transplantation for acute lymphoblastic leukemia: why do adolescents and young adults outcomes differ from those of children? A retrospective study on behalf of the Francophone Society of Stem Cell Transplantation and Cellular Therapy (SFGM-TC)

PURPOSE

In the acute lymphoblastic leukemia (ALL) landscape, adolescents and young adults (AYA) often present high-risk diseases and increased chemotherapy-related toxicity. Studies analyzing the outcomes of AYA after hematopoietic stem cell transplantation (HSCT) are scarce. Our study aimed to compare the outcomes of children and AYA with ALL after HSCT and to determine the factors influencing potential differences.

METHOD

891 patients, from the SFGM-TC registry, aged between 1 and 25 years who received HSCT between 2005 and 2012 were included. The outcomes of AYA were compared to the ones of their younger counterparts.

RESULTS

Five-year OS and GRFS were lower in AYA: 53.1% versus 64% and 36% versus 47% (p = 0.0012 and p = 0.007, respectively). WhileCIR was similar in both groups, 5 year-treatment related mortality was higher in AYA: 19% versus 13% (p = 0.04). The lower GRFS in AYA was mainly explained by a higher chronic graft versus host disease (cGvHD) incidence: 32% versus 19% (p < 0.001). Use of peripheral blood stem cells and use of anti-thymoglobulin appeared to be the main factors impacting cGvHD occurrence in AYA.

CONCLUSION

AYA have worse outcomes than children after HSCT for ALL because of a greater risk of TRM due to cGvHD. HSCT practices should be questioned in this population.

Three-Year Update of Tisagenlecleucel in Pediatric and Young Adult Patients With Relapsed/Refractory Acute Lymphoblastic Leukemia in the ELIANA Trial

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.In the primary analysis of the global phase II ELIANA trial (ClinicalTrials.gov identifier: NCT02435849), tisagenlecleucel provided an overall remission rate of 81% in pediatric and young adult patients with relapsed or refractory B-cell acute lymphoblastic leukemia (R/R B-ALL), with 59% of responders remaining relapse-free at 12 months. Here, we report an update on efficacy, safety, and patient-reported quality of life in 79 pediatric and young adult patients with R/R B-ALL following a median follow-up of 38.8 months. The overall remission rate was 82%. The median event-free survival was 24 months, and the median overall survival was not reached. Event-free survival was 44% (95% CI, 31 to 57) and overall survival was 63% (95% CI, 51 to 73) at 3 years overall (most events occur within the first 2 years). The estimated 3-year relapse-free survival with and without censoring for subsequent therapy was 52% (95% CI, 37 to 66) and 48% (95% CI, 34 to 60), respectively. No new or unexpected long-term adverse events were reported. Grade 3/4 adverse events were reported in 29% of patients > 1 year after infusion; grade 3/4 infection rate did not increase > 1 year after infusion. Patients reported improvements in quality of life up to 36 months after infusion. These findings demonstrate favorable long-term safety and suggest tisagenlecleucel as a curative treatment option for heavily pretreated pediatric and young adult patients with R/R B-ALL.

Outcomes of Childhood Noninfant Acute Lymphoblastic Leukemia With 11q23/KMT2A Rearrangements in a Modern Therapy Era: A Retrospective International Study

PURPOSE

We aimed to study prognostic factors and efficacy of allogeneic hematopoietic stem-cell transplantation (allo-HSCT) in first remission of patients with noninfant childhood acute lymphoblastic leukemia (ALL) with 11q23/KMT2A rearrangements treated with chemotherapy regimens between 1995 and 2010.

PATIENTS AND METHODS

Data were retrospectively retrieved from 629 patients with 11q23/KMT2A-rearranged ALL from 17 members of the Ponte-di-Legno Childhood ALL Working Group. Clinical and biologic characteristics, early response assessed by minimal residual disease at the end of induction (EOI) therapy, and allo-HSCT were analyzed for their impact on outcomes.

RESULTS

A specific 11q23/KMT2A translocation partner gene was identified in 84.3% of patients, with the most frequent translocations being t(4;11)(q21;q23) (n = 273; 51.5%), t(11;19)(q23;p13.3) (n = 106; 20.0%), t(9;11)(p21_22;q23) (n = 76; 14.3%), t(6;11)(q27;q23) (n = 20; 3.8%), and t(10;11)(p12;q23) (n = 14; 2.6%); 41 patients (7.7%) had less frequently identified translocation partner genes. Patient characteristics and early response varied among subgroups, indicating large biologic heterogeneity and diversity in therapy sensitivity among 11q23/KMT2A-rearranged ALL. The EOI remission rate was 93.2%, and the 5-year event-free survival (EFS) for the entire cohort was 69.1% ± 1.9%, with a range from 41.7% ± 17.3% for patients with t(9;11)-positive T-ALL (n = 9) and 64.8% ± 3.0% for patients with t(4;11)-positive B-ALL (n = 266) to 91.2% ± 4.9% for patients with t(11;19)-positive T-ALL (n = 34). Low EOI minimal residual disease was associated with favorable EFS, and induction failure was particularly predictive of nonresponse to further therapy and relapse and poor EFS. In addition, EFS was not improved by allo-HSCT compared with chemotherapy only in patients with both t(4;11)-positive B-ALL (n = 64 v 51; P = .10) and 11q23/KMT2A-rearranged T-ALL (n = 16 v 10; P = .69).

CONCLUSION

Compared with historical data, prognosis of patients with noninfant 11q23/KMT2A-rearranged ALL has improved, but allo-HSCT failed to affect outcome. Targeted therapies are needed to reduce relapse and treatment-related mortality rates.

Brothers and sisters of childhood acute leukemia survivors: Their long-term quality of life and its determinants

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 < 0.001), but a lower score for relationship with family than survivors (p < 0.001). In adult siblings, Mental Component Summary score was lower than general population (p < 0.001). Level of siblings' QoL was linked with female gender, but no association was found with cancer-related factors.

CONCLUSION

Brothers and sisters expressed a divergent perception of their long-term QoL depending on their age. To minimize the impact from childhood to adulthood, long-term attention should also be paid to siblings, often referred as "forgotten children".

Ovarian Function and Spontaneous Pregnancy After Hematopoietic Stem Cell Transplantation for Leukemia Before Puberty: An L.E.A. Cohort Study

Ovarian function impairment and infertility are among the most frequent late effects after hematopoietic stem cell transplantation (HSCT). The aim of this study was to evaluate ovarian function, occurrence of premature ovarian insufficiency (POI), and spontaneous pregnancy in a large cohort of adult survivor women who had undergone HSCT for leukemia before puberty. We conducted a retrospective observational study in women from the national cohort L.E.A., the long-term French follow-up program after childhood leukemia. The median follow-up duration was 18 years (14.2-23.3) after HSCT. Among 178 women, 106 (60%) needed pubertal induction with hormone substitution treatment, whereas 72 (40%) had spontaneous menarche. After spontaneous menarche, 33 (46%) developed POI, mostly within 5 years of HSCT. Older age at time of HSCT and cryopreservation of ovarian tissue appeared as significant risk factors for POI. More than 65% of patients who underwent HSCT before the age of 4.8 years had spontaneous menarche, and almost 50% didn't have POI at last evaluation, whereas more than 85% with HSCT after the age of 10.9 years didn't have spontaneous menarche and needed induction of puberty with hormone replacement therapy. Twenty-two women (12%) had at least one spontaneous pregnancy, with 17 live-births, 14 miscarriages, 4 legal abortions, and 2 therapeutic abortions. These results add supplementary data to better counsel patients and their families on the chances of ovarian residual function and pregnancy after HSCT, as well as on the potential interest of fertility preservation.

Symptomatic osteonecrosis in French survivors of childhood and adolescent leukemia: a clinical and MRI study of LEA cohort

Osteonecrosis (ON) is a known complication of acute leukemia (AL) management, affecting 1%-10% of young patients and resulting in long-term morbidity. Widespread access to MRI over the past decade has allowed earlier detection and more accurate assessment. This study investigated clinical and MRI features of the 129 (2.5%) patients with symptomatic ON retrospectively recruited from the French LEA (Leucémies de l'Enfant et de l'Adolescent, or child and adolescent leukemias) cohort (n = 4,973). We analyzed data concerning ON risk factors, multifocal involvement, severe lesions detected by MRI, and patient quality of life (QoL). ON patients tended to be >10 years old at the time of AL diagnosis (odds ratio [OR]: 22.46; p < 10^-6), female (OR: 1.8; p = 0.002), or treated for relapse (OR: 1.81; p = 0.041). They more frequently suffered from other sequelae (p < 10^-6). Most necroses involved weight-bearing joints, and they were multifocal in 69% of cases. Double-blinded review of MRIs for 39 patients identified severe lesions in 14, usually in the hips. QoL of adolescents and adults was poor and permanently impacted after onset of ON. In conclusion, age >10 at time of AL diagnosis, female sex, and relapse occurrence were risk factors for multifocal ON; MRI revealed severe ON in a third of the patients considered; and ON was associated with persistently poor QoL affecting multiple domains. Future studies should include prospective data addressing ON management and seek to identify genetic markers for targeted screening enabling early ON detection and treatment.

Clonal hematopoiesis driven by chromosome 1q/MDM4 trisomy defines a canonical route toward leukemia in Fanconi anemia

Fanconi anemia (FA) patients experience chromosome instability, yielding hematopoietic stem/progenitor cell (HSPC) exhaustion and predisposition to poor-prognosis myeloid leukemia. Based on a longitudinal cohort of 335 patients, we performed clinical, genomic, and functional studies in 62 patients with clonal evolution. We found a unique pattern of somatic structural variants and mutations that shares features of BRCA-related cancers, the FA-hallmark being unbalanced, microhomology-mediated translocations driving copy-number alterations. Half the patients developed chromosome 1q gain, driving clonal hematopoiesis through MDM4 trisomy downmodulating p53 signaling later followed by secondary acute myeloid lukemia genomic alterations. Functionally, MDM4 triplication conferred greater fitness to murine and human primary FA HSPCs, rescued inflammation-mediated bone marrow failure, and drove clonal dominance in FA mouse models, while targeting MDM4 impaired leukemia cells in vitro and in vivo. Our results identify a linear route toward secondary leukemogenesis whereby early MDM4-driven downregulation of basal p53 activation plays a pivotal role, opening monitoring and therapeutic prospects.

[Role of allogeneic hematopoietic cell transplantation after anti-CD19 CAR T-cell treatment: Guidelines from the SFGM-TC]

The role of allogeneic hematopoietic cell transplantation (allo-HCT) after CAR T- treatment cells in hematologic malignancies is currently controversial. Prolonged remissions after several years of follow-up suggest that there is a curative effect of CAR T-cells therapy, whereas allo-HCT was previously considered the only curative treatment in relapse situation. The aim of this harmonization workshop is to detail the existing data in the literature on the feasibility of allo-HCT after CAR T-cells and to propose to consider allograft in selected patients with B-acute lymphoblastic leukemia (B-ALL) and diffuse large B-cell lymphoma (DLBCL). In B-ALL, various intrinsic factors (inherent to the patient, to the disease, to the type of CAR T-cells) and especially various post CAR T-cells criteria (early expansion kinetics, residual disease at D28, early loss of B-cell aplasia) should lead to consider performing allo-HCT before the occurrence of a relapse. In DLBCL, although there are risk factors for relapse at diagnosis and prior to CAR T-cells therapy, response assessed by PET-CT at three months is critical and allo-HCT cannot currently be recommended in cases of complete or partial remission. In any case, if the age is appropriate for allogeneic transplantation, HLA typing should be performed before CAR T-cells treatment in order not to delay the allo-HCT project if needed.

Harnessing the MYB-dependent TAL1 5'super-enhancer for targeted therapy in T-ALL

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.

Preclinical Evaluation of a Novel Small Molecule Inhibitor of LIM Kinases (LIMK) CEL_Amide in Philadelphia-Chromosome Positive (BCR::ABL+) Acute Lymphoblastic Leukemia (ALL)

Ph+ (BCR::ABL+) B-ALL was considered to be high risk, but recent advances in BCR::ABL-targeting TKIs has shown improved outcomes in combination with backbone chemotherapy. Nevertheless, new treatment strategies are needed, including approaches without chemotherapy for elderly patients. LIMK1/2 acts downstream from various signaling pathways, which modifies cytoskeleton dynamics via phosphorylation of cofilin. Upstream of LIMK1/2, ROCK is constitutively activated by BCR::ABL, and upon activation, ROCK leads to the phosphorylation of LIMK1/2, resulting in the inactivation of cofilin by its phosphorylation and subsequently abrogating its apoptosis-promoting activity. Here, we demonstrate the anti-leukemic effects of a novel LIMK1/2 inhibitor (LIMKi) CEL_Amide in vitro and in vivo for BCR::ABL-driven B-ALL. The IC50 value of CEL_Amide was ≤1000 nM in BCR::ABL+ TOM-1 and BV-173 cells and induced dose-dependent apoptosis and cell cycle arrest in these cell lines. LIMK1/2 were expressed in BCR::ABL+ cell lines and patient cells and LIMKi treatment decreased LIMK1 protein expression, whereas LIMK2 expression was unaffected. As expected, CEL_Amide exposure caused specific activating downstream dephosphorylation of cofilin in cell lines and primary cells. Combination experiments with CEL_Amide and BCR::ABL TKIs imatinib, dasatinib, nilotinib, and ponatinib were synergistic for the treatment of both TOM-1 and BV-173 cells. CDKN2A^ko/BCR::ABL1+ B-ALL cells were transplanted in mice, which were treated with combinations of CEL_Amide and nilotinib or ponatinib, which significantly prolonged their survival. Altogether, the LIMKi CEL_Amide yields activity in Ph+ ALL models when combined with BCR::ABL-targeting TKIs, showing promising synergy that warrants further investigation.

Tisagenlecleucel therapy for relapsed or refractory B-cell acute lymphoblastic leukaemia in infants and children younger than 3 years of age at screening: an international, multicentre, retrospective cohort study

BACKGROUND

Children aged younger than 3 years were excluded from the ELIANA phase 2 trial of tisagenlecleucel in children with acute lymphoblastic leukaemia. The feasibility, safety, and activity of tisagenlecleucel have not been defined in this group, the majority of whom have high-risk (KMT2A-rearranged) infant acute lymphoblastic leukaemia and historically poor outcomes despite intensification of chemotherapy, and for whom novel therapies are urgently needed. We aimed to provide real-world outcome analysis of the feasibility, activity, and safety of tisagenlecleucel in younger children and infants with acute lymphoblastic leukaemia.

METHODS

We did an international, multicentre, retrospective cohort study at 15 hospitals across ten countries in Europe. Eligible patients were children aged younger than 3 years at screening between Sept 1, 2018, and Sept 1, 2021, who were screened for tisagenlecleucel therapy for relapsed or refractory B-cell precursor acute lymphoblastic leukaemia according to licensed indications. Patients received a single intravenous infusion of tisagenlecleucel. We tracked chimeric antigen receptor T-cell therapy outcomes using a standardised data reporting form. Overall survival, event-free survival, stringent event-free survival, B-cell aplasia, and toxicity were assessed in all patients who received a tisagenlecleucel infusion.

FINDINGS

38 eligible patients were screened, of whom 35 (92%) received a tisagenlecleucel infusion. 29 (76%) of 38 patients had KMT2A-rearranged acute lymphoblastic leukaemia, and 25 (66%) had relapsed after previous allogeneic haematopoietic stem-cell transplantation (HSCT). Patients had previously received a median of 2 lines (IQR 2-3) of (non-HSCT) therapy. Seven (18%) of 38 patients had received inotuzumab and 14 (37%) had received blinatumomab. After a median of 14 months (IQR 9-21) of follow-up, overall survival at 12 months after tisagenlecleucel infusion was 84% (64-93; five patients had died), event-free survival was 69% (47-83; nine events), and stringent event-free survival was 41% (23-58; 18 events). The probability of ongoing B-cell aplasia was 70% (95% CI 46-84; seven events) at 12 months. Adverse events included cytokine release syndrome, which occurred at any grade in 21 (60%) of 35 patients and at grade 3 or worse in five (14%), and neurotoxicity at any grade in nine (26%), none of which were severe. Measurable residual disease-negative complete response with or without haematological recovery occurred in 24 (86%) of 28 patients who had measurable disease.

INTERPRETATION

These data suggest that tisagenlecleucel has antitumour activity and has an acceptable safety profile for young children and infants with B-cell precursor acute lymphoblastic leukaemia.

FUNDING

None.

Oncogenetic landscape of T-cell lymphoblastic lymphomas compared to T-cell acute lymphoblastic leukemia

In the latest 2016 World Health Organization classification of hematological malignancies, T-cell lymphoblastic lymphoma (T-LBL) and lymphoblastic leukemia (T-ALL) are grouped together into one entity called T-cell lymphoblastic leukemia/lymphoma (T-LBLL). However, the question of whether these entities represent one or two diseases remains. Multiple studies on driver alterations in T-ALL have led to a better understanding of the disease while, so far, little data on genetic profiles in T-LBL is available. We sought to define recurrent genetic alterations in T-LBL and provide a comprehensive comparison with T-ALL. Targeted whole-exome next-generation sequencing of 105 genes, multiplex ligation-dependent probe amplification, and quantitative PCR allowed comprehensive genotype assessment in 818, consecutive, unselected, newly diagnosed patients (342 T-LBL vs. 476 T-ALL). The median age at diagnosis was similar in T-LBL and T-ALL (17 vs. 15 years old, respectively; p = 0.2). Although we found commonly altered signaling pathways and co-occurring mutations, we identified recurrent dissimilarities in actionable gene alterations in T-LBL as compared to T-ALL. HOX abnormalities (TLX1 and TLX3 overexpression) were more frequent in T-ALL (5% of T-LBL vs 13% of T-ALL had TLX1 overexpression; p = 0.04 and 6% of T-LBL vs 17% of T-ALL had TLX3 overexpression; p = 0.006). The PI3K signaling pathway was significantly more frequently altered in T-LBL as compared to T-ALL (33% vs 19%; p < 0.001), especially through PIK3CA alterations (9% vs 2%; p < 0.001) with PIK3CA^H1047 as the most common hotspot. Similarly, T-LBL genotypes were significantly enriched in alterations in genes coding for the EZH2 epigenetic regulator and in TP53 mutations (respectively, 13% vs 8%; p = 0.016 and 7% vs 2%; p < 0.001). This genetic landscape of T-LBLL identifies differential involvement of recurrent alterations in T-LBL as compared to T-ALL, thus contributing to better understanding and management of this rare disease.

Case Report: Hyperammonemic Encephalopathy Linked to Ureaplasma spp. and/or Mycoplasma hominis Systemic Infection in Patients Treated for Leukemia, an Emergency Not to Be Missed

Background

Hyperammonemic encephalopathy caused by Ureaplasma spp. and Mycoplasma hominis infection has been reported in immunocompromised patients undergoing lung transplant, but data are scarce in patients with hematological malignancies.

Case Presentation

We describe the cases of 3 female patients aged 11–16 years old, developing initially mild neurologic symptoms, rapidly evolving to coma and associated with very high ammonia levels, while undergoing intensive treatment for acute leukemia (chemotherapy: 2 and hematopoietic stem cell transplant: 1). Brain imaging displayed cerebral edema and/or microbleeding. Electroencephalograms showed diffuse slowing patterns. One patient had moderate renal failure. Extensive liver and metabolic functions were all normal. Ureaplasma spp. and M. hominis were detected by PCR and specific culture in two patients, resulting in prompt initiation of combined antibiotics therapy by fluoroquinolones and macrolides. For these 2 patients, the improvement of the neurological status and ammonia levels were observed within 96 h, without any long-term sequelae. M. hominis was detected post-mortem in vagina, using 16S rRNA PCR for the third patient who died of cerebral edema.

Conclusion

Hyperammonemic encephalopathy linked to Ureaplasma spp. and M. hominis is a rare complication encountered in immunocompromised patients treated for acute leukemia, which can lead to death if unrecognized. Combining our experience with the few published cases (n=4), we observed a strong trend among female patients and very high levels of ammonia, consistently uncontrolled by classical measures (ammonia-scavenging agents and/or continuous kidney replacement therapy). The reversibility of the encephalopathy without sequelae is possible with prompt diagnosis and adequate combined specific antibiotherapy. Any neurological symptoms in an immunocompromised host should lead to the measurement of ammonia levels. If increased, and in the absence of an obvious cause, it should prompt to perform a search for Ureaplasma spp. and M. hominis by PCR as well as an immediate empirical initiation of combined specific antibiotherapy.

Targeted inhibitors and antibody immunotherapies: Novel therapies for paediatric leukaemia and lymphoma

Despite improved outcomes achieved in the last decades for children with newly diagnosed leukaemia and lymphoma, treatment of patients with refractory/relapsed disease remains a challenge. The cure rate is still unsatisfactory and often achieved at the cost of significant morbidity. Exploring treatment with novel agents should offer less toxic therapeutic options, without compromising efficacy. Bispecific and antibody-drug conjugates targeting CD19 and CD22 (blinatumomab and inotuzumab ozogamicin) play an important role in the treatment of relapsed and refractory B-cell precursor acute lymphoblastic leukaemia (BCP-ALL); antibodies targeting CD123 and CD38 are also under investigation for acute myeloid leukaemia (AML) and T-ALL, respectively. Targeted therapy with small molecules is of primary importance for specific genetic subtypes, such as BCR-ABL-positive ALL, FLT3-ITD AML and anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma. KMT2A-directed targeted therapy with menin inhibitors holds promise to be of relevance in KMT2A-rearranged leukaemias, known to have dismal prognosis. Target inhibition in cellular pathways such as BCL-2, RAS, MEK, Bruton's tyrosine kinase, JAK-STAT or CDK4/CDK6 inhibition may be suitable for different diseases with common mutated pathways. Nevertheless, development and approval of new agents for paediatric cancers lags behind adult therapeutic options. New regulations were implemented to accelerate drug development for children. Considering the number of oncology medicinal products available for adults and the rarity of paediatric cancers, prioritisation based on scientific evidence and medical need, as well as international collaboration, is critical. Herein, we review the current status of drug development for children with leukaemia and lymphoma, excluding cellular therapy despite its well-known significance.

Clinico-biological features of T-cell acute lymphoblastic leukemia with fusion proteins

T-cell acute lymphoblastic leukemias (T-ALL) represent 15% of pediatric and 25% of adult ALL. Since they have a particularly poor outcome in relapsed/refractory cases, identifying prognosis factors at diagnosis is crucial to adapting treatment for high-risk patients. Unlike acute myeloid leukemia and BCP ALL, chromosomal rearrangements leading to chimeric fusion-proteins with strong prognosis impact are sparsely reported in T-ALL. To address this issue an RT-MPLA assay was applied to a consecutive series of 522 adult and pediatric T-ALLs and identified a fusion transcript in 20% of cases. PICALM-MLLT10 (4%, n = 23), NUP214-ABL1 (3%, n = 19) and SET-NUP214 (3%, n = 18) were the most frequent. The clinico-biological characteristics linked to fusion transcripts in a subset of 235 patients (138 adults in the GRAALL2003/05 trials and 97 children from the FRALLE2000 trial) were analyzed to identify their prognosis impact. Patients with HOXA trans-deregulated T-ALLs with MLLT10, KMT2A and SET fusion transcripts (17%, 39/235) had a worse prognosis with a 5-year EFS of 35.7% vs 63.7% (HR = 1.63; p = 0.04) and a trend for a higher cumulative incidence of relapse (5-year CIR = 45.7% vs 25.2%, HR = 1.6; p = 0.11). Fusion transcripts status in T-ALL can be robustly identified by RT-MLPA, facilitating risk adapted treatment strategies for high-risk patients.

Chimeric Antigen Receptor T-Cell Therapy in Paediatric B-Cell Precursor Acute Lymphoblastic Leukaemia: Curative Treatment Option or Bridge to Transplant?

Chimeric antigen receptor T-cell therapy (CAR-T) targeting CD19 has been associated with remarkable responses in paediatric patients and adolescents and young adults (AYA) with relapsed/refractory (R/R) B-cell precursor acute lymphoblastic leukaemia (BCP-ALL). Tisagenlecleucel, the first approved CD19 CAR-T, has become a viable treatment option for paediatric patients and AYAs with BCP-ALL relapsing repeatedly or after haematopoietic stem cell transplantation (HSCT). Based on the chimeric antigen receptor molecular design and the presence of a 4-1BB costimulatory domain, tisagenlecleucel can persist for a long time and thereby provide sustained leukaemia control. "Real-world" experience with tisagenlecleucel confirms the safety and efficacy profile observed in the pivotal registration trial. Recent guidelines for the recognition, management and prevention of the two most common adverse events related to CAR-T - cytokine release syndrome and immune-cell-associated neurotoxicity syndrome - have helped to further decrease treatment toxicity. Consequently, the questions of how and for whom CD19 CAR-T could substitute HSCT in BCP-ALL are inevitable. Currently, 40-50% of R/R BCP-ALL patients relapse post CD19 CAR-T with either CD19- or CD19+ disease, and consolidative HSCT has been proposed to avoid disease recurrence. Contrarily, CD19 CAR-T is currently being investigated in the upfront treatment of high-risk BCP-ALL with an aim to avoid allogeneic HSCT and associated treatment-related morbidity, mortality and late effects. To improve survival and decrease long-term side effects in children with BCP-ALL, it is important to define parameters predicting the success or failure of CAR-T, allowing the careful selection of candidates in need of HSCT consolidation. In this review, we describe the current clinical evidence on CAR-T in BCP-ALL and discuss factors associated with response to or failure of this therapy: product specifications, patient- and disease-related factors and the impact of additional therapies given before (e.g., blinatumomab and inotuzumab ozogamicin) or after infusion (e.g., CAR-T re-infusion and/or checkpoint inhibition). We discuss where to position CAR-T in the treatment of BCP-ALL and present considerations for the design of supportive trials for the different phases of disease. Finally, we elaborate on clinical settings in which CAR-T might indeed replace HSCT.

Novel Insights into Pediatric Acute Lymphoblastic Leukemia Ophthalmic Relapses from a Nationwide Cohort Study

Ten to fifteen percent of children with acute lymphoblastic leukemia (ALL) relapse following treatment. Of these, less than 2% display ophthalmic relapses, which owing to their scarcity, are largely undocumented, leaving clinicians with few diagnostic and therapeutic recommendations, despite serious functional sequelae. We conducted a French multicenter retrospective study to collect all clinical, radiological, biological, and therapeutic data, and outcomes for children with ALL ophthalmic relapses. From 2000 to 2020, 20 ophthalmic relapses occurring after first-line therapy performed before January 1^st, 2017 were included in our study: 14 B-ALL and 6 T-ALL. Fifteen patients (75%) had concomitant involvement of the central nervous system, and 11 (55%) a combined bone marrow relapse. Only 1 had an isolated ophthalmic relapse. Eight children (40%) died, 7 from a refractory disease and 1 from toxic death, and 4 patients relapsed. With a median follow-up of 63.1 months, 8 patients are currently alive in continuous complete remission with only 2 displaying severe ophthalmic sequelae. Although rare, ophthalmic relapse could have a significant impact on the functional prognosis of survivors. Their management must be multidisciplinary, with a central role given to ophthalmologists.

Biological Effects of BET Inhibition by OTX015 (MK-8628) and JQ1 in NPM1-Mutated (NPM1c) Acute Myeloid Leukemia (AML)

BET inhibitors (BETi) including OTX015 (MK-8628) and JQ1 demonstrated antileukemic activity including NPM1c AML cells. Nevertheless, the biological consequences of BETi in NPM1c AML were not fully investigated. Even if of better prognosis AML patients with NPM1c may relapse and treatment remains difficult. Differentiation-based therapy by all trans retinoic acid (ATRA) combined with arsenic trioxide (ATO) demonstrated activity in NPM1c AML. We found that BETi, similar to ATO + ATRA, induced differentiation and apoptosis which was TP53 independent in the NPM1c cell line OCI-AML3 and primary cells. Furthermore, BETi induced proteasome-dependent degradation of NPM1c. BETi degraded NPM1c in the cytosol while BRD4 is degraded in the nucleus which suggests that restoration of the NPM1/BRD4 equilibrium in the nucleus of NPM1c cells is essential for the efficacy of BETi. While ATO + ATRA had significant biological activity in NPM1c IMS-M2 cell line, those cells were resistant to BETi. Gene profiling revealed that IMS-M2 cells probably resist to BETi by upregulation of LSC pathways independently of the downregulation of a core BET-responsive transcriptional program. ATO + ATRA downregulated a NPM1c specific HOX gene signature while anti-leukemic effects of BETi appear HOX gene independent. Our preclinical results encourage clinical testing of BETi in NPM1c AML patients.

[DESCAR-T, a nationwide registry for patient treated by CAR-T Cells in France]

CAR-T Cells have opened new doors for cellular immunotherapies and provides new therapeutic options for patients with refractory B-cell malignancies, B-cell acute lymphoblastic leukemia and diffuse large B-cel lymphoma. CAR-T Cells have benefited from an accelerated approval procedure in many countries. Indeed, The French health authorities have approved the specialties Tisacel ® and Axicel ®, but additional data including the use of CAR-T Cells in real life were also mandatory. In regard to the scientific interest of the project, LYSA-LYSARC committed itself to prospectively and retrospectively collect information on patients eligible for CAR-T Cells as required by French health authorities. Other academic cooperating groups (GRAALL, IFM, SFCE, FILO and the scientific society SFGM-TC) were associated to this initiative which aims to build a nationwide CAR-T Cells devoted registry, so-called DESCART (Dispositif d'Enregistrement et Suivi des patients traités par CAR-T cells). DESCAR-T is a real-life multicentric registry set up in French sites qualified for CAR-T Cells treatment. DESCAR-T objective is to describe the use of CAR-T Cells in real life. All paediatric and adult patients with hematological malignancy fulfilling CAR-T Cells approval criteria and for whom a CAR-T Cells therapy has been discussed are included from 1 July 2018. Clinical data are directly collected from medical records and patients are treated according to the centers' routine practices. One of the distinctive features of DESCAR-T is its link with HTA for CAR-T Cells s reimbursement by the French public health system. DESCAR-T is the first national registry promoted by an academic group allowing centralized data collection for both academic and HTA/health authorities' purposes.

Different Clinical Presentations and Outcomes of Disseminated Varicella in Children With Primary and Acquired Immunodeficiencies

Primary infection with varicella-zoster virus (VZV) causes chickenpox, a benign and self-limited disease in healthy children. In patients with primary or acquired immunodeficiencies, primary infection can be life-threatening, due to rapid dissemination of the virus to various organs [lung, gastrointestinal tract, liver, eye, central nervous system (CNS)]. We retrospectively described and compared the clinical presentations and outcomes of disseminated varicella infection (DV) in patients with acquired (AID) (n= 7) and primary (PID) (n= 12) immunodeficiencies. Patients with AID were on immunosuppression (mostly steroids) for nephrotic syndrome, solid organ transplantation or the treatment of hemopathies, whereas those with PID had combined immunodeficiency (CID) or severe CID (SCID). The course of the disease was severe and fulminant in patients with AID, with multiple organ failure, no rash or a delayed rash, whereas patients with CID and SICD presented typical signs of chickenpox, including a rash, with dissemination to other organs, including the lungs and CNS. In the PID group, antiviral treatment was prolonged until immune reconstitution after bone marrow transplantation, which was performed in 10/12 patients. Four patients died, and three experienced neurological sequelae. SCID patients had the worst outcome. Our findings highlight substantial differences in the clinical presentation and course of DV between children with AID and PID, suggesting differences in pathophysiology. Prevention, early diagnosis and treatment are required to improve outcome.

Therapeutic potential of ruxolitinib and ponatinib in patients with EPOR-rearranged Philadelphia chromosome-like acute lymphoblastic leukemia

Not available.

A Semi-Mechanistic Population Pharmacokinetic/Pharmacodynamic Model of Bortezomib in Pediatric Patients with Relapsed/Refractory Acute Lymphoblastic Leukemia

INTRODUCTION

The pharmacokinetics (PK) of the 20S proteasome inhibitor bortezomib are characterized by a large volume of distribution and a rapid decline in plasma concentrations within the first hour after administration. An increase in exposure was observed in the second week of treatment, which has previously been explained by extensive binding of bortezomib to proteasome in erythrocytes and peripheral tissues. We characterized the nonlinear population PK and pharmacodynamics (PD) of bortezomib in children with acute lymphoblastic leukemia.

METHODS

Overall, 323 samples from 28 patients were available from a pediatric clinical study investigating bortezomib at an intravenous dose of 1.3 mg/m² twice weekly (Dutch Trial Registry number 1881/ITCC021). A semi-physiological PK model for bortezomib was first developed; the PK were linked to the decrease in 20S proteasome activity in the final PK/PD model.

RESULTS

The plasma PK data were adequately described using a two-compartment model with linear elimination. Increased concentrations were observed in week 2 compared with week 1, which was described using a Langmuir binding model. The decrease in 20S proteasome activity was best described by a direct effect model with a sigmoidal maximal inhibitory effect, representing the relationship between plasma concentrations and effect. The maximal inhibitory effect was 0.696 pmol AMC/s/mg protein (95% confidence interval 0.664-0.728) after administration.

CONCLUSION

The semi-physiological model adequately described the nonlinear PK and PD of bortezomib in plasma. This model can be used to further optimize dosing of bortezomib.

Determinants of CD19-positive vs CD19-negative relapse after tisagenlecleucel for B-cell acute lymphoblastic leukemia

Tisagenlecleucel therapy has shown promising efficacy for relapsed/refractory (R/R) B-cell precursor acute lymphoblastic leukemia (BCP-ALL). However, relapses occur in 30-50% of patients. Determinants for CD19^pos versus CD19^neg relapses are poorly characterized. We report on 51 patients with R/R BCP-ALL (median age 17 years) infused with tisagenlecleucel after lymphodepletion. Complete remission rate at D28 was 96%. Prior blinatumomab increased the risk of early failure at D28. The 18-month cumulative incidence of relapse (CIR), event-free survival (EFS), and overall survival (OS) were 51%, 44%, and 74%, respectively, at a median follow-up of 15.5 months. Factors associated with a high tumor burden (occurrence of cytokine release syndrome) and prior blinatumomab were associated with an increased CIR, and a shorter EFS and OS. Pre-lymphodepletion high disease burden (MRD ≥ 10^-2, SHR 10.4, p = 0.03) and detectable MRD at D28 (SHR 7.2, p = 0.006) correlated with an increased risk of CD19^neg relapse. Low disease burden (SHR 5.3, p = 0.03) and loss of B-cell aplasia (BCA) (SHR 21.7, p = 0.004) predicted an increased risk of CD19^pos relapses. These data highlight the impact of prior therapy on patient outcome. Finally, detectable MRD at D28 and loss of BCA both define patients at high risk of relapse for whom additional interventions are needed.

Oncogenetic landscape and clinical impact of IDH1 and IDH2 mutations in T-ALL

IDH1 and IDH2 mutations (IDH1/2^Mut) are recognized as recurrent genetic alterations in acute myeloid leukemia (AML) and associated with both clinical impact and therapeutic opportunity due to the recent development of specific IDH1/2^Mut inhibitors. In T-cell acute lymphoblastic leukemia (T-ALL), their incidence and prognostic implications remain poorly reported. Our targeted next-generation sequencing approach allowed comprehensive assessment of genotype across the entire IDH1 and IDH2 locus in 1085 consecutive unselected and newly diagnosed patients with T-ALL and identified 4% of, virtually exclusive (47 of 49 patients), IDH1/2^Mut. Mutational patterns of IDH1/2^Mut in T-ALL present some specific features compared to AML. Whereas IDH2^R140Q mutation was frequent in T-ALL (25 of 51 mutations), the IDH2^R172 AML hotspot was absent. IDH2 mutations were associated with older age, an immature phenotype, more frequent RAS gain-of-function mutations and epigenetic regulator loss-of-function alterations (DNMT3A and TET2). IDH2 mutations, contrary to IDH1 mutations, appeared to be an independent prognostic factor in multivariate analysis with the NOTCH1/FBXW7/RAS/PTEN classifier. IDH2^Mut were significantly associated with a high cumulative incidence of relapse and very dismal outcome, suggesting that IDH2-mutated T-ALL cases should be identified at diagnosis in order to benefit from therapeutic intensification and/or specific IDH2 inhibitors.

COVID19 and acute lymphoblastic leukemias of children and adolescents: Updated recommendations (Version 2) of the Leukemia Committee of the French Society for the fight against Cancers and leukemias in children and adolescents (SFCE)

Since the emergence of the SARS-CoV-2 infection, many recommendations have been made. However, the very specific nature of acute lymphoblastic leukemias and their treatment in children and adolescents led the Leukemia Committee of the French Society for the fight against Cancers and leukemias in children and adolescents (SFCE) to propose more specific recommendations. Here is the second version of these recommendations updated according to the evolution of knowledge on COVID19.

Case Report: Targeting 2 Antigens as a Promising Strategy in Mixed Phenotype Acute Leukemia: Combination of Blinatumomab With Gemtuzumab Ozogamicin in an Infant With a KMT2A-Rearranged Leukemia

Mixed phenotype acute leukemia (MPAL) accounts for 2-5% of leukemia in children. MPAL are at higher risk of induction failure. Lineage switch (B to M or vice versa) or persistence of only the lymphoid or myeloid clone is frequently observed in biphenotypic/bilineal cases, highlighting their lineage plasticity. The prognosis of MPAL remains bleak, with an event-free survival (EFS) of less than 50% in children. A lymphoid-type therapeutic approach appears to be more effective but failures to achieve complete remission (CR) remain significant. KMT2A fusions account for 75-80% of leukemia in infants under one year of age and remains a major pejorative prognostic factor in the Interfant-06 protocol with a 6 years EFS of only 36%. The search for other therapeutic approaches, in particular immunotherapies that are able to eradicate all MPAL clones, is a major issue. We describe here the feasibility and tolerance of the combination of two targeted immunotherapies, blinatumomab and Gemtuzumab Ozogamicin, in a 4-year-old infant with a primary refractory KTM2A-rearranged MPAL. Our main concern was to determine how to associate these two immunotherapies and we describe how we decided to do it with the parents’ agreement. The good MRD response on the two clones made it possible to continue the curative intent with a hematopoietic stem cell transplant at 9 months of age. Despite a relapse at M11 post-transplant because of the recurrence of a pro-B clone retaining the initial lymphoid phenotype, the child is now 36 months old, in persistent negative MRD CR2 for 12 months after a salvage chemotherapy and an autologous CAR T cells infusion, with no known sequelae to date. This case study can thus lead to the idea of a sequential combination of two immunotherapies targeting two distinct leukemic subclones (or even a single biphenotypic clone), as a potential one to be tested prospectively in children MPAL and even possibly all KMT2A-rearranged infant ALL.

Testosterone deficiency in men surviving childhood acute leukemia after treatment with hematopoietic stem cell transplantation or testicular radiation: an L.E.A. study

We included 255 patients from the L.E.A. French long-term follow-up cohort. All had received hematopoietic stem cell transplantation (HSCT) and/or testicular radiation for childhood acute leukemia and were older than 18 years at last L.E.A. evaluation. Total testosterone deficiency was defined as a <12 nmol/l level or by substitutive therapy, partial deficiency as normal testosterone with elevated luteinizing hormone (>10 UI/l). After myeloablative total body irradiation (n = 178), 55.6% had total deficiency, 15.7% partial deficiency, and 28.7% were normal. A 4-6 Gy testicular boost and a younger age at HSCT increased significantly the risk. After a Busulfan-containing myeloablative conditioning regimen (n = 53), 28.3% had total deficiency, 15.1% partial deficiency, 56.6% were normal (62.5% vs. 0% in patients without or with additional testicular radiation). A 24-Gy testicular radiation without HSCT induced total or partial deficiency in 71.4% and 28.6%, respectively (n = 21). Total testosterone deficiency increased the risk of metabolic syndrome: 25% vs. 12.1% in men with partial testosterone deficiency and 8.8% when Leydig cell function was normal (p = 0.031).

Synergy of FLT3 inhibitors and the small molecule inhibitor of LIM kinase1/2 CEL_Amide in FLT3-ITD mutated Acute Myeloblastic Leukemia (AML) cells

Patients with FLT3-ITD mutated (FLT3-ITD+) Acute Myeloid Leukemia (AML), have frequently relapsed or refractory disease and FLT3-ITD+ inhibitors have limited efficacy. Rho kinases (ROCK) are constitutively activated by FLT3-ITD+ in AML via PI3 kinase and Rho GTPase. Upon activation by ROCK, LIM kinases (LIMK) inactivate cofilin by phosphorylation which affects cytoskeleton dynamics, cell growth and apoptosis. LIMK inhibition leads to cofilin activation via dephosphorylation and activated cofilin localizes to mitochondria inducing apoptosis. Thus, we investigated the therapeutic potential of the LIMK1/2 inhibitor CEL_Amide (LIMKi) in FLT3-ITD+ AML. Expression of LIMK1/2 in FLT3-ITD+ cell lines MOLM-13 and MV-4-11 cells could be detected by RT-qPCR and at the protein level. IC50 after LIMKi monotherapy was 440 nM in MOLM-13 cells and 420 nM in MV4-11 cells. Treatment with LIMKi decreased LIMK1 protein levels and repression of inactivating phosphorylation of cofilin in FLT3-ITD+ cells. Combination experiments with LIMKi and FLT3 inhibitors including midostaurin, crenolanib and gilteritinib were synergistic for treatment of MOLM-13 cells while combinations with quizartinib were additive. Combinations of LIMKi and the hypomethylating agent azacitidine or the ROCK inhibitor fasudil were additive. In NOD-SCID mice engrafted with MOLM13-LUC cells, the FLT3 inhibitor midostaurin and LIMKi delayed MOLM13-LUC engraftment as detected by in vivo bioluminescence imaging and the LIMKi and midostaurin combination prolonged significantly survival of leukemic mice. LIMK1/2 inhibition by the small molecule CEL_Amide seems to have promising activity in combination with FLT3 inhibitors in vitro as well as in vivo and may constitute a novel treatment strategy for FLT3-ITD+ AML.