How I treat long-term survivors of childhood acute leukemia.

ABSTRACT: The population of survivors of childhood leukemia who reach adulthood is growing due to improved therapy. However, survivors are at risk of long-term complications. Comprehensive follow-up programs play a key role in childhood leukemia survivor care. The major determinant of long-term complications is the therapeutic burden accumulated over time. Relapse chemotherapy, central nervous system irradiation, hematopoietic stem cell transplantation, and total body irradiation are associated with greater risk of long-term complications. Other parameters include clinical characteristics such as age and sex as well as environmental, genetic, and socioeconomic factors, which can help stratify the risk of long-term complications and organize follow-up program. Early diagnosis improves the management of several late complications such as anthracycline-related cardiomyopathy, secondary cancers, metabolic syndrome, development defects, and infertility. Total body irradiation is the treatment associated with worse long-term toxicity profile with a wide range of complications. Patients treated with chemotherapy alone are at a lower risk of long-term complications, although the optimal long-term follow-up remains unclear. Novel immunotherapies and targeted therapy are generally associated with a better short-term safety profile but still require careful long-term toxicity monitoring. Advances in understanding genetic susceptibility to long-term complications could enable tailored therapeutic strategies for leukemia treatment and optimized follow-up programs.

Childhood Langerhans cell histiocytosis hematological involvement: severity associated with BRAFV600E loads.

Hematological involvement (HI) is one of the life-threatening risk organs (ROs) in Langerhans cell histiocytosis (LCH). Lahey criteria have defined HI since 1975 as hemoglobin <10 g/dL and/or platelets <100 G/L and/or leukopenia (white blood cell count <4 G/L) and/or neutrophils <1.5 G/. Among the 2313 patients <18 years old enrolled in the French National Histiocytosis Registry (1983-2023), 331 developed HI (median age at diagnosis: 1 year); median follow-up lasted 8.1 years. Bone-marrow aspirate smears and biopsies may show reactive histiocytes, hemophagocytosis or myelofibrosis but never confirm the diagnosis. Fifty-eight (17%) patients developed macrophage-activation syndrome, sometimes related to acute Epstein-Barr virus or cytomegalovirus infection, sometimes months before typical LCH manifestations appeared. Hemoglobin and platelet thresholds for initiating transfusion(s) appear to accurately distinguish 2 groups: mild HI (MHI; >7 g/dL and >20 G/L, respectively) and severe HI (SHI; ≤7 g/dL and ≤20 G/L). Each entity has different organ involvements, laboratory parameters, mutational status, blood BRAFV600E loads, drug sensitivities and outcomes (respective MHI and SHI 10-year survival rates: 98% and 73%). Since 1998, mortality first declined with combination Cladribine-cytarabine therapy, and then with mitogen-activated protein-kinase inhibitors since 2014. Forty-one (12%) patients developed neurodegenerative complications that have emerged as a risk for long-term survivors. These results suggest limiting the HI-RO definition to SHI, as it encompasses almost all medical complications of LCH. Future clinical trials might demonstrate that targeted-therapy approaches would be better adapted for these patients, while MHI can be managed with classic therapies.

Molecular and clinicopathologic characterization of pediatric histiocytoses.

The spectrum of somatic mutations in pediatric histiocytoses and their clinical implications are not fully characterized, especially for non-Langerhans cell histiocytosis (-LCH) subtypes. A cohort of 415 children with histiocytosis from the French histiocytosis registry was reviewed and analyzed for BRAFV600E . Most BRAFWT samples were analyzed by next-generation sequencing (NGS) with a custom panel of genes for histiocytosis and myeloid neoplasia. Of 415 case samples, there were 366 LCH, 1 Erdheim-Chester disease, 21 Rosai-Dorfman disease (RDD), 21 juvenile xanthogranuloma (JXG, mostly with severe presentation), and 6 malignant histiocytosis (MH). BRAFV600E was the most common mutation found in LCH (50.3%, n = 184). Among 105 non-BRAFV600E -mutated LCH case samples, NGS revealed mutations as follows: MAP2K1 (n = 44), BRAF exon 12 deletions (n = 26), and duplications (n = 8), other BRAF V600 codon mutation (n = 4), and non-MAP-kinase pathway genes (n = 5). Wild-type sequences were identified in 17.1% of samples. BRAFV600E was the only variant significantly correlated with critical presentations: organ-risk involvement and neurodegeneration. MAP-kinase pathway mutations were identified in seven RDD (mostly MAP2K1) and three JXG samples, but most samples were wild-type on NGS. Finally, two MH samples had KRAS mutations, and one had a novel BRAFG469R mutation. Rarely, we identified mutations unrelated to MAP-kinase pathway genes. In conclusion, we characterized the mutational spectrum of childhood LCH and clinical correlations of variants and subtypes. Variants responsible for JXG and RDD were not elucidated in more than half of the cases, calling for other sequencing approaches.

Therapeutic approach and outcome of children with Philadelphia chromosome-positive acute lymphoblastic leukemia at first relapse in the era of tyrosine kinase inhibitors: An SFCE retrospective study.

BACKGROUND: Since the introduction of tyrosine kinase inhibitors (TKIs), the profile of pediatric relapse of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) has changed. However, the management of pediatric Ph+ ALL relapses is not currently standardized. PROCEDURE: We retrospectively analyzed the therapeutic strategies and outcomes of pediatric Ph+ ALL patients in first relapse who were initially treated with a TKI-containing regimen in one of the French pediatric hematology centers from 2004 to 2019. RESULTS: Twenty-seven children experienced a Ph+ ALL relapse: 24 (89%) had an overt relapse and three a molecular relapse. Eight involved the central nervous system. A second complete remission (CR2) was obtained for 26 patients (96%). Induction consisted of nonintensive chemotherapy for 13 patients (48%) and intensive chemotherapy for 14 (52%). Thirteen patients (48%) received consolidation. Allogenic hematopoietic stem cell transplantation (alloHSCT) was performed for 21 patients (78%). The TKI was changed for 23 patients (88%), mainly with dasatinib (n = 15). T315I was the most common mutation at relapse (4/7). The 4-year event-free survival and survival rates were 60.9% and 76.1%, respectively. Survival was positively associated with alloHSCT in CR2. CONCLUSION: We show that pediatric first-relapse Ph+ ALL reinduces well with a second course of TKI exposure, despite the use of different therapeutic approaches. The main prognostic factor for survival was alloHSCT in CR2. Because of the small size of the cohort, we could not draw any conclusions about the respective impact of TKIs, but the predominance of the T315I mutation should encourage careful consideration of the TKI choice.

Compliance with Early Long-Term Prophylaxis Guidelines for Severe Hemophilia A.

OBJECTIVES: To evaluate the applicability and compliance with guidelines for early initiation of long-term prophylaxis in infants with severe hemophilia A and to identify factors associated with guideline compliance. STUDY DESIGN: This real-world, prospective, multicenter, population-based FranceCoag study included almost all French boys with severe hemophilia A, born between 2000 and 2009 (ie, after guideline implementation). RESULTS: We included 333 boys in the study cohort. The cumulative incidence of long-term prophylaxis use was 61.2% at 3 years of age vs 9.5% in a historical cohort of 39 boys born in 1996 (ie, before guideline implementation). The guidelines were not applicable in 23.1% of patients due to an early intracranial bleeding or inhibitor development. Long-term prophylaxis was delayed in 10.8% of patients. In the multivariate analysis, 2 variables were significantly associated with "timely long-term prophylaxis" as compared with "delayed long-term prophylaxis": hemophilia treating center location in the southern regions of France (OR 23.6, 95% CI 1.9-286.7, P = .013 vs Paris area) and older age at long-term prophylaxis indication (OR 7.2 for each additional year, 95% CI 1.2-43.2, P = .031). Long-term prophylaxis anticipation was observed in 39.0% of patients. Earlier birth year (OR 0.5, 95% CI 0.3-0.8, P = .010 for birth years 2005-2009 vs 2000-2004) and age at first factor replacement (OR 1.9 for each additional year, 95% CI 1.2-3.0, P = .005) were significantly associated with "long-term prophylaxis guideline compliance" vs "long-term prophylaxis anticipation." CONCLUSIONS: This study suggests that long-term prophylaxis guidelines are associated with increased long-term prophylaxis use. However, early initiation of long-term prophylaxis remains a challenge.

Invasive Fungal Infections in Immunocompromised Children: Novel Insight Following a National Study.

OBJECTIVE: To obtain a national overview of the epidemiology and management of invasive fungal infections (IFIs) in France for severely immunocompromised children who were treated for acute leukemia or had undergone allogeneic hematopoietic stem cell transplantation (a-HSCT). STUDY DESIGN: We performed a national multicenter retrospective study to collect epidemiologic data for proven and probable IFIs in children with acute leukemia under first- line or relapse treatment or who had undergone a-HSCT. We also conducted a prospective practice survey to provide a national overview of IFI management in pediatric hematology units. RESULTS: From January 2014 to December 2017, 144 cases of IFI were diagnosed (5.3%) in 2721 patients, including 61 cases of candidiasis, 60 cases of aspergillosis, and 23 cases of infection with "emergent" fungi, including 10 cases of mucormycosis and 6 cases of fusariosis. The IFI rate was higher in patients with acute myelogenous leukemia (12.9%) (OR, 3.24; 95% CI, 2.15-4.81; P < .0001) compared with the rest of the cohort. Patients undergoing a-HSCT had an IFI rate of only 4.3%. In these patients, the use of primary antifungal prophylaxis (principally fluconazole) was associated with a lower IFI rate (OR, 0.28; 95% CI, 0.14-0.60; P = 4.90 ×10-4) compared with a-HSCT recipients who did not receive antifungal prophylaxis. The main cause of IFI in children receiving prophylaxis was emergent pathogens (41%), such as mucormycosis and fusariosis, which were resistant to the prophylactic agents. CONCLUSIONS: The emerging fungi and new antifungal resistance profiles uncovered in this study should be considered in IFI management in immunocompromised children.

Metronomic Maintenance With Weekly Vinblastine After Induction With Bevacizumab-Irinotecan in Children With Low-grade Glioma Prevents Early Relapse.

BACKGROUND: Pediatric low-grade glioma (pLGG) represents the most common brain tumor in childhood. Previous studies have reported that a therapeutic strategy on the basis of the association of bevacizumab alone (B) or in combination with irinotecan (BI) could produce rapid tumor response and clinical improvement in children with pLGG. Nevertheless, a majority of patients relapses shortly (median, 5 mo) after stopping B or BI treatment. We proposed metronomic maintenance with weekly vinblastine added after a 6 months induction of B/BI to prevent early relapse. PATIENTS AND METHODS: Monocentric retrospective analysis of a patient with pLGG treated with B or BI for 6 months followed by a 12-month maintenance with weekly vinblastine (6 mg/m²) from October 2012 to September 2019 in a single institution. RESULTS: In total, 18 patients (7 males and 11 females) were identified. Because of progression during the B or BI induction 2/18 children were excluded. In total, 16 patients were analyzed with a median age of 10 years (range, 4 to 16 y). A total of 13 patients received BI and 3 patients received B alone. The mean duration of induction was 6.2 months (range, 2 to 12 mo). After induction 5/16 patients had a partial radiologic response, 11/16 patients had stable disease. All patients started maintenance (median duration, 12 mo; range, 3 to 12 mo). With a median follow-up of 3.9 years after the end of B or BI (range, 11 mo to 7.2 y), 15/16 patients were alive and 9/16 patients were progression-free. Seven of 16 children progressed with a median time to progression of 23 months (ranges, 5 to 39 mo). Three of 16 (18%) children progressed during vinblastine maintenance and 4/16 (25%) patients after the end of maintenance. After the total duration of treatment, clinical improvement was noted in 4 patients, 9 patients had stable symptoms, and only 3 patients progressed. One and 2-year event-free survival were, respectively, 81.2% and 56.2%. Two-year overall survival was 93.7%. CONCLUSIONS: We report here, the potential benefit and the improvement of progression-free survival by adding metronomic maintenance with weekly vinblastine after initial induction with B or BI in children with low-grade glioma.

Novel ACTN1 variants in cases of thrombocytopenia.

The ACTN1 gene has been implicated in inherited macrothrombocytopenia. To decipher the spectrum of variants and phenotype of ACTN1-related thrombocytopenia, we sequenced the ACTN1 gene in 272 cases of unexplained chronic or familial thrombocytopenia. We identified 15 rare, monoallelic, nonsynonymous and likely pathogenic ACTN1 variants in 20 index cases from 20 unrelated families. Thirty-one family members exhibited thrombocytopenia. Targeted sequencing was carried out on 12 affected relatives, which confirmed presence of the variant. Twenty-eight of 32 cases with monoallelic ACTN1 variants had mild to no bleeding complications. Eleven cases harbored 11 different unreported ACTN1 variants that were monoallelic and likely pathogenic. Nine variants were located in the α-actinin-1 (ACTN1) rod domain and were predicted to hinder dimer formation. These variants displayed a smaller increase in platelet size compared with variants located outside the rod domain. In vitro expression of the new ACTN1 variants induced actin network disorganization and led to increased thickness of actin fibers. These findings expand the repertoire of ACTN1 variants associated with thrombocytopenia and highlight the high frequency of ACTN1-related thrombocytopenia cases. The rod domain, like other ACTN1 functional domains, may be mutated resulting in actin disorganization in vitro and thrombocytopenia with normal platelet size in most cases.

Adolescence and Socioeconomic Factors: Key Factors in the Long-Term Impact of Leukemia on Scholastic Performance-A LEA Study.

OBJECTIVE: To evaluate the association between medical and social environmental factors and the risk of repeating a grade in childhood leukemia survivors. STUDY DESIGN: A cross-sectional study of childhood leukemia survivors, recruited through the LEA cohort (Leucémie de l'Enfant et de l'Adolescent [French Childhood Cancer Survivor Study for Leukemia]) in 2014. An adjusted logistic regression model was used to identify variables linked to repeating a grade after the diagnosis among the survivors, and the rates of repeating a grade were compared between the survivors and their siblings using a multilevel logistic regression model. RESULTS: The mean age at inclusion of the 855 participants was 16.2 ± 7.0 years, and the mean duration of follow-up from diagnosis to evaluation was 10.2 ± 6.2 years. After disease onset, 244 patients (28.5%) repeated a grade, with a median interval of 4 years (IQR, 2-8 years). Independent factors associated with repeating a grade were male sex (OR, 1.78; 95% CI, 1.21-2.60), adolescence (OR, 2.70; 95% CI, 1.63-4.48), educational support during the treatment period (OR, 3.79; 95% CI, 2.45-5.88), low parental education level (OR, 2.493; 95% CI, 1.657-3.750), and household financial difficulties (OR, 2.62; 95% CI, 1.607-4.28). Compared with siblings, survivors were at greater risk of repeating a grade (OR, 1.87; 95% CI, 1.48-2.35). CONCLUSIONS: The most vulnerable patients seemed to be adolescents and those with parents of low socioeconomic status. Improving the schooling career of leukemia survivors will require that the medical community more carefully consider the social status of patients.

Prevalence and characteristics of metabolic syndrome in adults from the French childhood leukemia survivors' cohort: a comparison with controls from the French population.

The prevalence of the metabolic syndrome among adults from the French LEA childhood acute leukemia survivors' cohort was prospectively evaluated considering the type of anti-leukemic treatment received, and compared with that of controls. The metabolic profile of these patients was compared with that of controls. A total of 3203 patients from a French volunteer cohort were age- and sex-matched 3:1 to 1025 leukemia survivors (in both cohorts, mean age: 24.4 years; females: 51%). Metabolic syndrome was defined according to the National Cholesterol Education Program's Adult Treatment Panel III criteria. Metabolic syndrome was found in 10.3% of patients (mean follow-up duration: 16.3±0.2 years) and 4.5% of controls, (OR=2.49; P<0.001). Patients transplanted with total body irradiation presented the highest risk (OR=6.26; P<0.001); the other treatment groups also showed a higher risk than controls, including patients treated with chemotherapy only. Odd Ratios were 1.68 (P=0.005) after chemotherapy only, 2.32 (P=0.002) after chemotherapy and cranial irradiation, and 2.18 (P=0.057) in patients transplanted without irradiation. Total body irradiation recipients with metabolic syndrome displayed a unique profile compared with controls: smaller waist circumference (91 vs 99.6 cm; P=0.01), and increased triglyceride levels (3.99 vs 1.5 mmol/L; P<0.001), fasting glucose levels (6.2 vs 5.6 mmol/L; P=0.049), and systolic blood pressure (137.9 vs 132.8 mmHg; P=0.005). By contrast, cranial irradiation recipients with metabolic syndrome had a larger waist circumference (109 vs 99.6 cm; P=0.007) than controls. Regardless of the anti-leukemic treatment, metabolic syndrome risk was higher among childhood leukemia survivors. Its presentation differed depending on the treatment type, thus suggesting a divergent pathophysiology. This study is registered at clinicaltrials.gov identifier: 01756599.

Macrothrombocytopenia and dense granule deficiency associated with FLI1 variants: ultrastructural and pathogenic features.

Congenital macrothrombocytopenia is a family of rare diseases, of which a significant fraction remains to be genetically characterized. To analyze cases of unexplained thrombocytopenia, 27 individuals from a patient cohort of the Bleeding and Thrombosis Exploration Center of the University Hospital of Marseille were recruited for a high-throughput gene sequencing study. This strategy led to the identification of two novel FLI1 variants (c.1010G>A and c.1033A>G) responsible for macrothrombocytopenia. The FLI1 variant carriers' platelets exhibited a defect in aggregation induced by low-dose adenosine diphosphate (ADP), collagen and thrombin receptor-activating peptide (TRAP), a defect in adenosine triphosphate (ATP) secretion, a reduced mepacrine uptake and release and a reduced CD63 expression upon TRAP stimulation. Precise ultrastructural analysis of platelet content was performed using transmission electron microscopy and focused ion beam scanning electron microscopy. Remarkably, dense granules were nearly absent in the carriers' platelets, presumably due to a biogenesis defect. Additionally, 25-29% of the platelets displayed giant α-granules, while a smaller proportion displayed vacuoles (7-9%) and autophagosome-like structures (0-3%). In vitro study of megakaryocytes derived from circulating CD34+ cells of the carriers revealed a maturation defect and reduced proplatelet formation potential. The study of the FLI1 variants revealed a significant reduction in protein nuclear accumulation and transcriptional activity properties. Intraplatelet flow cytometry efficiently detected the biomarker MYH10 in FLI1 variant carriers. Overall, this study provides new insights into the phenotype, pathophysiology and diagnosis of FLI1 variant-associated thrombocytopenia.

Germline variants in ETV6 underlie reduced platelet formation, platelet dysfunction and increased levels of circulating CD34+ progenitors.

Variants in ETV6, which encodes a transcription repressor of the E26 transformation-specific family, have recently been reported to be responsible for inherited thrombocytopenia and hematologic malignancy. We sequenced the DNA from cases with unexplained dominant thrombocytopenia and identified six likely pathogenic variants in ETV6, of which five are novel. We observed low repressive activity of all tested ETV6 variants, and variants located in the E26 transformation-specific binding domain (encoding p.A377T, p.Y401N) led to reduced binding to corepressors. We also observed a large expansion of megakaryocyte colony-forming units derived from variant carriers and reduced proplatelet formation with abnormal cytoskeletal organization. The defect in proplatelet formation was also observed in control CD34+ cell-derived megakaryocytes transduced with lentiviral particles encoding mutant ETV6. Reduced expression levels of key regulators of the actin cytoskeleton CDC42 and RHOA were measured. Moreover, changes in the actin structures are typically accompanied by a rounder platelet shape with a highly heterogeneous size, decreased platelet arachidonic response, and spreading and retarded clot retraction in ETV6 deficient platelets. Elevated numbers of circulating CD34+ cells were found in p.P214L and p.Y401N carriers, and two patients from different families suffered from refractory anemia with excess blasts, while one patient from a third family was successfully treated for acute myeloid leukemia. Overall, our study provides novel insights into the role of ETV6 as a driver of cytoskeletal regulatory gene expression during platelet production, and the impact of variants resulting in platelets with altered size, shape and function and potentially also in changes in circulating progenitor levels.

Metabolic syndrome in long-term survivors of childhood acute leukemia treated without hematopoietic stem cell transplantation: an L.E.A. study.

Cardiovascular conditions are serious long-term complications of childhood acute leukemia. However, few studies have investigated the risk of metabolic syndrome, a known predictor of cardiovascular disease, in patients treated without hematopoietic stem cell transplantation. We describe the overall and age-specific prevalence, and the risk factors for metabolic syndrome and its components in the L.E.A. (Leucémie de l'Enfant et de l'Adolescent) French cohort of childhood acute leukemia survivors treated without hematopoietic stem cell transplantation. The study included 650 adult patients (mean age at evaluation: 24.2 years; mean follow-up after leukemia diagnosis: 16.0 years). The prevalence of metabolic syndrome was 6.9% (95% CI 5.1-9.2). The age-specific cumulative prevalence at 20, 25, 30 and 35 years of age was 1.3%, 6.1%, 10.8% and 22.4%, respectively. The prevalence of decreased high-density lipoprotein cholesterol, increased triglycerides, increased fasting glucose, increased blood pressure and increased abdominal circumference was 26.8%, 11.7%, 5.8%, 36.7% and 16.7%, respectively. Risk factors significantly associated with metabolic syndrome in the multivariate analysis were male sex (OR 2.64; 95% CI 1.32-5.29), age at last evaluation (OR 1.10; 95% CI 1.04-1.17) and body mass index at diagnosis (OR 1.15; 95% CI 1.01-1.32). The cumulative steroid dose was not a significant risk factor. Irradiated and non-irradiated patients exhibited different patterns of metabolic abnormalities, with more frequent abdominal obesity in irradiated patients and more frequent hypertension in non-irradiated patients. Survivors of childhood acute leukemia are at risk of metabolic syndrome, even when treated without hematopoietic stem cell transplantation or central nervous system irradiation. A preventive approach with regular screening for cardiovascular risk factors is recommended. clinicaltrials.gov identifier:01756599.