Peripheral blood stem cell collection in children with extremely low body weight (≤8 kg). What have we learned over the past 25 years and where are the limits?

Hematopoietic progenitor cells-apheresis (HPC-A) collection is now a routine procedure for autologous hematopoietic stem cell transplantation. Here we present our 25 years' experience of HPC-A collection in children weighing 8 kg or less, with a focus on the evolution of our standard operating procedures, and the safety limits for these young patients, in the Pediatric Apheresis Unit of Clermont-Ferrand University Hospital (France). Fifteen children weighing 8 kg or less underwent 26 HPC-A collections over 25 years. Median CD34+ cell yield by leukapheresis was 4.4 106 /kg. No procedure-related complications were encountered during or after the collection. No patient had profound thrombocytopenia or anemia that needed post-collection transfusions. Our experience in pediatric oncology patients who underwent HPC-A collections shows that this procedure can be performed even in the smallest of children with no increase in toxicity provided all precautions are taken to ensure that the procedure is carried out under the ideal conditions.

Functional classification of ATM variants in ataxia-telangiectasia patients.

Ataxia-telangiectasia (A-T) is a recessive disorder caused by biallelic pathogenic variants of ataxia-telangiectasia mutated (ATM). This disease is characterized by progressive ataxia, telangiectasia, immune deficiency, predisposition to malignancies, and radiosensitivity. However, hypomorphic variants may be discovered associated with very atypical phenotypes, raising the importance of evaluating their pathogenic effects. In this study, multiple functional analyses were performed on lymphoblastoid cell lines from 36 patients, comprising 49 ATM variants, 24 being of uncertain significance. Thirteen patients with atypical phenotype and presumably hypomorphic variants were of particular interest to test strength of functional analyses and to highlight discrepancies with typical patients. Western-blot combined with transcript analyses allowed the identification of one missing variant, confirmed suspected splice defects and revealed unsuspected minor transcripts. Subcellular localization analyses confirmed the low level and abnormal cytoplasmic localization of ATM for most A-T cell lines. Interestingly, atypical patients had lower kinase defect and less altered cell-cycle distribution after genotoxic stress than typical patients. In conclusion, this study demonstrated the pathogenic effects of the 49 variants, highlighted the strength of KAP1 phosphorylation test for pathogenicity assessment and allowed the establishment of the Ataxia-TeLangiectasia Atypical Score to predict atypical phenotype. Altogether, we propose strategies for ATM variant detection and classification.

Follow-up of post-transplant minimal residual disease and chimerism in childhood lymphoblastic leukaemia: 90 d to react.

Relapse after transplantation is a major cause of treatment failure in paediatric acute lymphoblastic leukaemia (ALL). Here, we report the findings of a prospective national study designed to investigate the feasibility of immune intervention in children in first or subsequent remission following myeloablative conditioning. This study included 133 children who received a transplant for ALL between 2005 and 2008. Minimal Residual Disease (MRD) based on T cell receptor/immunoglobulin gene rearrangements was measured on days -30, 30, 90 and 150 post-transplantation. Ciclosporin treatment was rapidly discontinued and donor lymphocyte infusions (DLI) were programmed for patients with a pre- or post-transplant MRD status ≥10(-3) . Only nine patients received DLI. Pre- and post-transplant MRD status, and the duration of ciclosporin were independently associated with 5-year overall survival (OS), which was 62·07% for the whole cohort. OS was substantially higher in patients cleared of MRD than in those with persistent MRD (52·3% vs. 14·3%, respectively). Only pre-transplant MRD status (Hazard Ratio 2·57, P = 0·04) and duration of ciclosporin treatment (P < 0·001) were independently associated with relapse. The kinetics of chimerism were not useful for predicting relapse, whereas MRD monitoring up to 90 d post-transplantation was a valuable prognostic tool to guide therapeutic intervention.

Cohort Profile: the French childhood cancer survivor study for leukaemia (LEA Cohort).

The main aim of the Leucémies de l'Enfant et l'Adolescent (LEA) project (Childhood and Adolescent Leukaemia) is to study the determinants (medical, socioeconomic, behavioural and environmental) of medium- and long-term outcomes of patients treated for childhood acute leukaemia (AL). The LEA study began in 2004 and is based on a French multicentric prospective cohort. Included are children treated for AL since January 1980 (incident and prevalent cases), surviving at month 24 for myeloblastic AL and lymphoblastic AL grafted in first complete remission or at month 48 for lymphoblastic AL not grafted in first complete remission. Information is collected during specific medical visits and notably includes the following data: socioeconomic data, AL history, physical late effects (such as fertility, cardiac function and metabolic syndrome) and quality of life. Data are collected every 2 years until the patient is 20 years old and has had a 10-year follow-up duration from diagnosis or last relapse. Thereafter, assessments are planned every 4 years. In active centres in 2013, eligible patients number more than 3000. The cohort has already included 2385 survivors, with rate of exhaustiveness of almost 80%. Data access can be requested from principal coordinators and must be approved by the steering committee.

Leukapheresis in management of hyperleukocytosis in children's leukemias.

We describe 16 leukapheresis (LK) procedures performed in 7 children with different types of leukemia and hyperleukocytosis. We also provide an analysis of previously published experiences of pediatric LK. Median age and body weight of patients were 12.3 years (range, 0.2 to 16.7 y) and 49 kg (range, 5 to 61 kg). Immediate pre-first-LK median white blood cell count was 478×10/L (108×10/L to 988×10/L). All cytoreduction were performed on Cobe Spectra cell separator. Sixty-eight percent of procedures were performed with peripheral veins. Extracorporeal line had been primed with red blood cell for 31% of LK. The median decrease in white blood cell count after each LK was 33% (0% to 69%), and overall decrease after completion of LK procedures was 62% (11% to 94%). Only minor clinical adverse events and no metabolic complication were attributable to LK. No more clinical symptom of hyperleukocytosis was observed after completion of LK procedures. Our findings are consistent with reported results in other pediatric series: LK is a well-tolerated procedure that can be safely performed with an experienced pediatric team even on the smallest children.

Clinical value of pre-transplant minimal residual disease in childhood lymphoblastic leukaemia: the results of the French minimal residual disease-guided protocol.

Minimal residual disease (MRD) is a major predictive factor of the cure rate of acute lymphoblastic leukaemia (ALL). Haematopoietic cell transplantation is a treatment option for patients at high risk of relapse. Between 2005 and 2008, we conducted a prospective study evaluating the feasibility and efficacy of the reduction of immunosuppressive medication shortly after a non-ex vivo T depleted myeloablative transplantation. Immunoglobulin (Ig)H/T-cell receptor MRD 30 d before transplant could be obtained in 122 of the 133 cases of high-risk paediatric ALL enrolled. There were no significant demographic differences except remission status (first or second complete remission) between the 95 children with MRD <10(-3) and the 27 with MRD ≥10(-3) . Multivariate analysis identified sex match and MRD as being significantly associated with 5-year survival. MRD ≥10(-3) compromised the 5-year cumulative incidence of relapse (43·6 vs. 16·7%). Complete remission status and stem cell source did not modify the relationship between MRD and prognosis. Thus, pre-transplant MRD is still a major predictor of outcome for ALL. The MRD-guided strategy resulted in survival for 72·3% of patients with MRD<10(-3) and 40·4% of those with MRD ≥10(-3).

Prevalence and risk factors of cataract after chemotherapy with or without central nervous system irradiation for childhood acute lymphoblastic leukaemia: an LEA study.

Corticosteroid and central nervous system (CNS) irradiation can induce cataract in childhood lymphoblastic leukaemia survivors. Few prospective studies with systematic ophthalmological evaluation have been published. Cataract was prospectively assessed by serial slip lamp tests in 517 patients. All had acute lymphoblastic leukaemia, all had been treated by chemotherapy with or without CNS irradiation, and none had received haematopoietic stem cell transplantation. Median ages at last evaluation and follow-up duration from leukaemia diagnosis were 16·8 and 10·9 years, respectively. Cataract was observed in 21/517 patients (4·1%). Cumulative incidence was 4·5 ± 1·2% at 15 years and reached 26 ± 8·1% at 25 years. CNS irradiation was the only risk factor: prevalence was 11·1% in patients who had received irradiation and 2·8% in those who did not. We did not detect any steroid dose effect: cumulative dose was 5133 and 5190 mg/m(2) in patients with and without cataract, respectively. Cataract occurrence did not significantly impact quality of life. We conclude that, in the range of steroid dose reported here, the cataract risk proves very low 15 years after treatment without CNS irradiation but an even more prolonged follow-up is required because of potential very late occurrence.

Peripheral blood stem cell collection in low-weight children: retrospective comparison of two apheresis devices.

BACKGROUND: Apheresis is a major challenge in peripheral stem cell collection from low-weight children with cancer. Comparisons between the new apheresis device Optia (TerumoBCT) and the earlier COBE Spectra (CaridianBCT) have been performed in adults but not in low-weight children. The objective was to compare the performance of these two devices in small children. STUDY DESIGN AND METHODS: In this retrospective study, all patients were reviewed weighing less than 15 kg undergoing stem cell collection using the Optia device between April 2011 and April 2012. They were paired on weight in a 3:1 ratio with patients whose cells had been collected with the COBE Spectra since 2006. RESULTS: Six patients were treated with the Optia and were matched with 18 patients treated with the Spectra. No side effects occurred. Collection efficiency (CE) was similar between the two groups (50% vs. 47%), but CD34 cell blood clearance was lower with the Optia (0.4 mL/min/kg vs. 0.6 mL/min/kg, p < 0.01). Platelet (PLT) loss and hemoglobin (Hb) loss were significantly reduced with the Optia (respectively, 32% vs. 54%, p < 0.01; and 1.4 g/dL vs. 2.9 g/dL, p < 0.01). Apheresis duration was increased with the Optia (159 min vs. 134 min, p < 0.05). The cell product harvested with the Optia had a lower volume and lower hematocrit, but similar white blood cell and PLT content. CONCLUSION: Compared with the Spectra, the Optia allows similar CE with a reduced PLT and Hb loss but with a longer duration.

Improvement of the management of infants, children and adults with a molecular diagnosis of Enterovirus meningitis during two observational study periods.

Enteroviruses (EVs) are a major cause of aseptic meningitis, and RNA detection using molecular assay is the gold standard diagnostic test. The aim of this study was to assess the impact of an EV positive diagnosis on the clinical management of patients admitted for meningitis over the course of two observational study periods (2005 and 2008-09) in the same clinical departments. We further investigated in multivariate analysis various factors possibly associated with hospital length of stay (LOS) in all age groups (infants, children, and adults). The results showed an overall improvement in the management of patients (n = 142) between the study periods, resulting in a significantly shorter hospital LOS for adults and children, and a shorter duration of antibiotic use for adults and infants. In multivariate analysis, we observed that the time from molecular test results to discharge of patients and the median duration of antibiotic treatment were associated with an increase in LOS in all age groups. In addition, among adults, the turnaround time of the molecular assay was significantly correlated with LOS. The use of CT scan in children and hospital admission outside the peak of EV prevalence in infants tended to increase LOS. In conclusion, the shorter length of stay of patients with meningitis in this study was due to various factors including the rapidity of the EV molecular test (particularly in adults), greater physician responsiveness after a positive result (in adults and children), and greater experience on the part of physicians in handling EV meningitis, as evidenced by the shorter duration of antibiotic use in adults and infants.

Mobilization of hematopoietic stem cells by plerixafor alone in children: a sequential Bayesian trial.

BACKGROUND: The rapid kinetics of hematopoietic stem cells induced by Plerixafor (Mozobil®, Genzyme) should be of particular interest in children. We therefore conducted a prospective trial to determine whether a one-day mobilization by plerixafor alone was efficient enough in children with cancer. METHODS: Children with solid malignancies were consecutively recruited for this phase-IIA, Bayesian single-center prospective study. Mobilization consisted in one subcutaneous injection of 240 µg plerixafor/kg body weight at 8a.m. (h0). Collection by apheresis began at h5 provided that CD34+count exceeded 10 × 10(6)/L. Our main evaluation criterion was percent of children in which at least 5 × 10(6) CD34+/kg could be collected during the first apheresis. RESULTS: No patients fulfilled the success criterion, and so a stopping criterion was met after 5 patients. All patients reached the threshold value of 10 × 10(6) CD34+cells/L post-injection and so all were eligible for apheresis. Peak CD34+cell values were ranged from 11 to 44 × 10(6)/L and were reached in 4h to 6h. No side-effects were observed. Median number of CD34+cells collected per patient BW was 1.62 × 10(6)[0.47-3.5]. In 3 of the 5 patients, collection was>1.5 × 10(6) CD34+/kg BW. CONCLUSION: In children, a 'one-day' mobilization regimen consisting of one injection of 240 µg/kg plerixafor alone in hematological steady state provides a faster and shorter mobilization than in adults. This strategy may be an attractive option for completing an insufficient graft. More studies are warranted to optimize the use of plerixafor in children.