Granulocyte colony-stimulating factor (G-CSF) treatment of childhood acute myeloid leukemias that overexpress the differentiation-defective G-CSF receptor isoform IV is associated with a higher incidence of relapse

The Impact of Prophylactic Post-Chemotherapy G-CSF on the Relapse Rates in Patients with Acute Myeloid Leukemia: A Meta-Analysis

This meta-analysis evaluated the impact of prophylactic post-chemotherapy granulocyte colony-stimulating factor (G-CSF) in patients with acute myeloid leukemia (AML). Overall, the relapse rate, overall survival, event-free survival, and mortality rate were similar in G-CSF (+) compared to G-CSF (-) patients. However, the relative risk (RR) of relapse was higher in children and in secondary AML patients who were treated with G-CSF compared to the G-CSF (-) group [RR, 95% confidence interval: 1.26, 1.04-1.52, and 1.12 (1.02-1.24)]. Treatment with post-chemotherapy G-CSF should be prescribed with caution in pediatric patients with AML and secondary AML as possibly increasing the relapse risk.

Effectiveness and safety of primary prophylaxis with G-CSF after induction therapy for acute myeloid leukemia: a systematic review and meta-analysis of the clinical practice guidelines for the use of G-CSF 2022 from the Japan society of clinical oncology

Although granulocyte colony-stimulating factor (G-CSF) reduces the incidence, duration, and severity of neutropenia, its prophylactic use for acute myeloid leukemia (AML) remains controversial due to a theoretically increased risk of relapse. The present study investigated the effects of G-CSF as primary prophylaxis for AML with remission induction therapy. A detailed literature search for related studies was performed using PubMed, Ichushi-Web, and the Cochrane Library. Data were independently extracted and assessed by two reviewers. A qualitative analysis of pooled data was conducted, and the risk ratio with corresponding confidence intervals was calculated in the meta-analysis and summarized. Sixteen studies were included in the qualitative analysis, nine of which were examined in the meta-analysis. Although G-CSF significantly shortened the duration of neutropenia, primary prophylaxis with G-CSF did not correlate with infection-related mortality. Moreover, primary prophylaxis with G-CSF did not affect disease progression/recurrence, overall survival, or adverse events, such as musculoskeletal pain. However, evidence to support or discourage the use of G-CSF as primary prophylaxis for adult AML patients with induction therapy remains limited. Therefore, the use of G-CSF as primary prophylaxis can be considered for adult AML patients with remission induction therapy who are at a high risk of infectious complications.

Supportive care in pediatric acute myeloid leukemia:Expert-based recommendations of the NOPHO-DB-SHIP consortium

INTRODUCTION

Pediatric acute myeloid leukemia (AML) is the second most common type of pediatric leukemia. Patients with AML are at high risk for several complications such as infections, typhlitis, and acute and long-term cardiotoxicity. Despite this knowledge, there are no definite supportive care guidelines as to what the best approach is to manage or prevent these complications.

AREA COVERED

The NOPHO-DB-SHIP (Nordic-Dutch-Belgian-Spain-Hong-Kong-Israel-Portugal) consortium, in preparation for a new trial in pediatric AML patients, had dedicated meetings for supportive care. In this review, the authors discuss the available data and outline recommendations for the management of children and adolescents with AML with an emphasis on hyperleukocytosis, tumor lysis syndrome, coagulation abnormalities and bleeding, infection, typhlitis, malnutrition, cardiotoxicity, and fertility preservation.

EXPERT OPINION

Improved supportive care has significantly contributed to increased cure rates. Recommendations on supportive care are an essential part of treatment for this highly susceptible population and will further improve their outcome.

A review of granulocyte colony-stimulating factor receptor signaling and regulation with implications for cancer

Granulocyte colony-stimulating factor receptor (GCSFR) is a critical regulator of granulopoiesis. Studies have shown significant upregulation of GCSFR in a variety of cancers and cell types and have recognized GCSFR as a cytokine receptor capable of influencing both myeloid and non-myeloid immune cells, supporting pro-tumoral actions. This systematic review aims to summarize the available literature examining the mechanisms that control GCSFR signaling, regulation, and surface expression with emphasis on how these mechanisms may be dysregulated in cancer. Experiments with different cancer cell lines from breast cancer, bladder cancer, glioma, and neuroblastoma are used to review the biological function and underlying mechanisms of increased GCSFR expression with emphasis on actions related to tumor proliferation, migration, and metastasis, primarily acting through the JAK/STAT pathway. Evidence is also presented that demonstrates a differential physiological response to aberrant GCSFR signal transduction in different organs. The lifecycle of the receptor is also reviewed to support future work defining how this signaling axis becomes dysregulated in malignancies.

Neutropenia and Infection Prophylaxis in Childhood Cancer

PURPOSE OF REVIEW

Pediatric oncology patients frequently experience episodes of prolonged neutropenia which puts them at high risk for infection with significant morbidity and mortality. Here, we review the data on infection prophylaxis with a focus on both pharmacologic and ancillary interventions. This review does not include patients receiving hematopoietic stem cell transplantation.

RECENT FINDINGS

Patients with hematologic malignancies are at highest risk for infection. Bacterial and fungal prophylaxis decrease the risk of infection in certain high-risk groups. Ancillary measures such as ethanol locks, chlorhexidine gluconate baths, GCSF, IVIG, and mandatory hospitalization do not have enough data to support routine use. There is limited data on risk of infection and role of prophylaxis in patients receiving immunotherapy and patients with solid tumors. Patients with Down syndrome and adolescent and young adult patients may benefit from additional supportive care measures and protocol modifications. Consider utilizing bacterial and fungal prophylaxis in patients with acute myeloid leukemia or relapsed acute lymphoblastic leukemia. More research is needed to evaluate other supportive care measures and the role of prophylaxis in patients receiving immunotherapy.

Minimally myelosuppressive regimen for remission induction in pediatric AML: long-term results of an observational study

Treatment refusal and death as a result of toxicity account for most treatment failures among children with acute myeloid leukemia (AML) in resource-constrained settings. We recently reported the results of treating children with AML with a combination of low-dose cytarabine and mitoxantrone or omacetaxine mepesuccinate with concurrent granulocyte colony-stimulating factor (G-CSF) (low-dose chemotherapy [LDC]) for remission induction followed by standard postremission strategies. We have now expanded the initial cohort and have provided long-term follow-up. Eighty-three patients with AML were treated with the LDC regimen. During the study period, another 100 children with AML received a standard-dose chemotherapy (SDC) regimen. Complete remission was attained in 88.8% and 86.4% of patients after induction in the LDC and SDC groups, respectively (P = .436). Twenty-two patients in the LDC group received SDC for the second induction course. Significantly more high-risk AML patients were treated with the SDC regimen (P = .035). There were no significant differences between the LDC and SDC groups in 5-year event-free survival (61.4% ± 8.7% vs 65.2% ± 7.4%, respectively; P = .462), overall survival (72.7% ± 6.9% vs 72.5% ± 6.2%, respectively; P = .933), and incidence of relapse (20.5% ± 4.5% vs 17.6% ± 3.9%, respectively; P = .484). Clearance of mutations based on the average variant allele frequency at complete remission in the LDC and SDC groups was 1.9% vs 0.6% (P < .001) after induction I and 0.17% vs 0.078% (P = .052) after induction II. In conclusion, our study corroborated the high remission rate reported for children with AML who received at least 1 course of LDC. The results, although preliminary, also suggest that long-term survival of these children is comparable to that of children who receive SDC regimens.

Pharmacokinetics and safety of pegylated recombinant human granulocyte colony-stimulating factor in children with acute leukaemia

AIMS

This open-label, phase I study evaluated the pharmacokinetics and safety of pegylated recombinant human granulocyte colony-stimulating factor (PEG-rhG-CSF) for the treatment of chemotherapy-induced neutropenia in children with acute leukaemia.

METHODS

PEG-rhG-CSF was administered as a single 100 mcg/kg (3 mg maximum dose) subcutaneous injection at the end of each chemotherapy period when neutropenia occurred. Blood samples were obtained from patients treated with PEG-rhG-CSF. PEG-rhG-CSF serum concentrations were determined by an enzyme-linked immunosorbent assay. Population pharmacokinetic (PPK) analysis was implemented using the nonlinear mixed-effects model. Short-term safety was evaluated through adverse events collection (registered at clinicaltrials.gov identifier: 03844360).

RESULTS

A total of 16 acute leukaemia patients (1.8-13.6 years) were included, of whom two (12.5%) had grade 3 neutropenia, six (37.5%) had grade 4 neutropenia, and eight (50.0%) had severe neutropenia. For PPK modelling, 64 PEG-rhG-CSF serum concentrations were obtainable. A one-compartment model with first-order elimination was used for pharmacokinetic data modelling. The current weight was a significant covariate. The median (range) of clearance (CL) and area under the serum concentration-time curve (AUC) were 5.65 (1.49-14.45) mL/h/kg and 16514.75 (6632.45-54423.30) ng·h/mL, respectively. Bone pain, pyrexia, anaphylaxis and nephrotoxicity were not observed. One patient died 13 days after administration, and the objective assessment of causality was that an association with PEG-rhG-CSF was "possible".

CONCLUSIONS

The AUC of PEG-rhG-CSF (100 mcg/kg, 3 mg maximum dose) in paediatric patients with acute leukaemia were similar to those of PEG-rhG-CSF (100 mcg/kg) in children with sarcoma. PEG-rhG-CSF is safe, representing an important therapeutic option for chemotherapy-induced neutropenia in paediatric patients with acute leukaemia.

Efficacy and cost-benefit of filgrastim administered after early assessment bone marrow biopsy during induction therapy for acute myeloid leukemia

The role of filgrastim during acute myeloid leukemia (AML) induction therapy remains controversial. At our institution, newly diagnosed AML patients from 2003 through 2019 were retrospectively evaluated. Patients were stratified on whether they received filgrastim within 5 days after early assessment bone marrow (BMBx) and divided into early GCSF group (eGCSF) and no-eGCSF group. A total of 121 patients were included. We found significantly shorter hospital stay (median 24 vs 26 days, p < .01), absolute neutrophil count recovery days (median 23 vs 25 days, p = .03), and intravenous antibiotics days (mean 18.5 vs 21.4 days, p = .01) in patients with eGCSF comparing with no-eGCSF. There was no significant difference regarding complete response rates; however, for those failed to achieve remission, eGCSF was associated with higher blast count. There was no significant difference regarding overall survival or progression-free survival. The use of eGCSF was associated with cost savings of $5199 per patient over no-eGCSF.

Association of fludarabin, cytarabine, and fractioned gemtuzumab followed by hematopoietic stem cell transplantation for first-line refractory acute myeloid leukemia in children: A single-center experience

CONTEXT

Acute myeloid leukemia (AML) is a rare disease in children, with only 50% to 60% event-free survival. Among patients with AML, 10% do not respond to first-line chemotherapy. There is no recommendation concerning second-line treatments. Gemtuzumab ozogamicin (GO) is a monoclonal antibody targeting CD33, linked to calicheamicin. We report the efficacy and tolerance of a salvage regimen of fludarabin, cytarabine, and GO (FLA-GO) in patients refractory to first-line treatment.

METHODS

Eight patients (median age 14.5 years), who had more than 2% minimal residual disease (MRD) by flow cytometry (MRD flow), received gemtuzumab 3 mg/m² on days 1, 4, 7, associated with cytarabine 2000 mg/m² and fludarabin 30 mg/m² on days 1 to 5.

RESULTS

Six patients achieved complete remission (CR) (blast count morphology ≤5 × 10^-2 , CR-MRD flow <1 × 10^-3 for four patients). Five patients received a second course. We observed 11 episodes of febrile neutropenia, including 6 septicemias without complication. There was no fungal infection or toxic death. Two patients received granulocyte colony stimulating factor. One patient had partial platelet recovery; one, prolonged pancytopenia. All patients received hematopoietic stem cell transplantation (HSCT). We observed five mild-to-severe sinusoidal obstruction syndromes during HSCT procedures, particularly in patients who did not receive defibrotide prophylaxis. At the date of last contact (median follow-up: 58 months; range: 22-78), six patients were in continuous CR with negative MRD. Two patients died of post-HSCT relapse.

CONCLUSION

FLA-GO is a good salvage regimen for pediatric refractory AML, with significant but acceptable toxicity. HSCT is mandatory to achieve sustained CR in these patients.

Pharmacological prophylaxis of infection in pediatric acute myeloid leukemia patients

Introduction: Pediatric patients treated for acute myeloid leukemia (AML) are at high risk of developing severe infectious complications. The choice of an optimum supportive treatment should be based on local epidemiology, as well as intensity and toxicity of the anti-leukemic therapy applied.Areas covered: This review presents an overview of recently published studies focusing on the prevention of infection in pediatric AML patients. PubMed has been systematically searched for clinical trials, reviews, and meta-analyses published in the last 10 years. The focus of this article will be limited to primary prophylaxis only, while secondary prophylaxis is beyond the scope of the current review.Expert opinion: Although anti-bacterial agents may decrease the bacterial infection burden, there is no consensus regarding prophylactic use. To that end, there is a need for further randomized controlled trials to establish the precise role of anti-bacterial prophylaxis in pediatric AML patients. The prophylactic use of anti-fungal agents is strongly recommended for all AML patients. Since the contribution of hematopoietic growth factors to improved survival has not been demonstrated, they should not be routinely applied. Decisions regarding an appropriate prophylactic strategy should be taken in collaboration with the infectious disease experts and pharmacology team.

Cytokine receptor splice variants in hematologic diseases

Cytokine and cytokine receptors are important regulators of hematopoiesis. Hematopoietic stem cells (HSCs) and progenitors differentiate into the myeloid or lymphoid lineage in response to specific cytokines. Cell-type specific receptors are expressed on committed progenitors that bind to other late-acting cytokines that are involved in terminal differentiation of hematopoietic cells. In normal hematopoiesis, these receptors undergo alternative splicing and are developmentally regulated. Splicing changes can significantly affect the structure and function of the receptors resulting in alterations of either the extracellular ligand binding domain or the cytoplasmic signaling domain responsible for cellular growth and differentiation. Most alternatively spliced isoforms generally lose the ability to promote differentiation. Evidently, overexpression of naturally occurring cytokine receptor alternate isoforms are observed in multiple myeloid diseases such as myelodysplastic syndromes (MDS), acute myeloid leukemia (AML), and polycythemia vera (PV). The purpose of this review is to introduce the various isoforms of key cytokine receptors that play a crucial role in myeloid development and their potential role in myeloid diseases.

Altered expression of CSF3R splice variants impacts signal response and is associated with SRSF2 mutations

Three annotated CSF3R mRNA splice variants have been described. CSF3R-V1 is the wild-type receptor, while CSF3R-V4 is a truncated form increased in some patients with AML. CSF3R-V3 mRNA was identified in placenta more than 20 years ago, but remains largely uncharacterized due to the lack of a suitable detection assay. Using a novel digital PCR method to quantitate expression of each CSF3R mRNA splice variant in hematopoietic cells, CSF3R-V1 was most highly expressed followed by CSF3R-V3. Functional assays revealed expression of V3 alone conferred a hypoproliferative phenotype associated with defective JAK-STAT activation. However, coexpression of V1 with V3 rescued proliferative responses. Comparative analysis of V3/V1 expression in CD34+ cells from healthy donors and patients with AML revealed a statistically significant increase in the V3/V1 ratio only in the subset of patients with AML harboring SRSF2 mutations. Knockout of SRFS2 in KG-1 and normal CD34+ cells decreased the V3/V1 ratio. Collectively, these data are the first to demonstrate expression of the CSF3R-V3 splice variant in primary human myeloid cells and a role for SRSF2 in modulating CSF3R splicing. Our findings provide confirmatory evidence that CSF3R is a target of SRSF2 mutations, which has implications for novel treatment strategies for SRSF2-mutated myeloid malignancies.

Use of granulocyte colony-stimulating factor and risk of relapse in pediatric patients treated for acute myeloid leukemia according to NOPHO-AML 2004 and DB AML-01

BACKGROUND

Supportive-care use of granulocyte colony-stimulating factor (G-CSF) in pediatric acute myeloid leukemia (AML) remains controversial due to a theoretical increased risk of relapse and limited impact on neutropenic complications. We describe the use of G-CSF in patients treated according to NOPHO-AML 2004 and DB AML-01 and investigated associations with relapse.

PROCEDURE

Patients diagnosed with de novo AML completing the first week of therapy and not treated with hematopoietic stem cell transplantation in the first complete remission were included (n = 367). Information on G-CSF treatment after each course (yes/no) was registered prospectively in the study database and detailed information was gathered retrospectively from each center. Descriptive statistics were used to describe G-CSF use and Cox regression to assess the association between G-CSF and risk of relapse.

RESULTS

G-CSF as supportive care was given to 128 (35%) patients after 268 (39%) courses, with a large variation between centers (0-93%). The use decreased with time-the country-adjusted odds ratio was 0.8/diagnostic year (95% confidence interval [CI] 0.7-0.9). The median daily dose was 5 μg/kg (range 3-12 μg/kg) and the median cumulative dose was 75 μg/kg (range 7-1460 μg/kg). Filgrastim was used in 82% of G-CSF administrations and infection was the indication in 44% of G-CSF administrations. G-CSF was associated with increased risk of relapse-the adjusted hazard ratio was 1.5 (95% CI 1.1-2.2).

CONCLUSIONS

G-CSF as supportive care was used in a third of patients, and use decreased with time. Our results indicate that the use of G-CSF may be associated with an increased risk of relapse.

Mutation, drift and selection in single-driver hematologic malignancy: Example of secondary myelodysplastic syndrome following treatment of inherited neutropenia

Cancer development is driven by series of events involving mutations, which may become fixed in a tumor via genetic drift and selection. This process usually includes a limited number of driver (advantageous) mutations and a greater number of passenger (neutral or mildly deleterious) mutations. We focus on a real-world leukemia model evolving on the background of a germline mutation. Severe congenital neutropenia (SCN) evolves to secondary myelodysplastic syndrome (sMDS) and/or secondary acute myeloid leukemia (sAML) in 30–40%. The majority of SCN cases are due to a germline ELANE mutation. Acquired mutations in CSF3R occur in >70% sMDS/sAML associated with SCN. Hypotheses underlying our model are: an ELANE mutation causes SCN; CSF3R mutations occur spontaneously at a low rate; in fetal life, hematopoietic stem and progenitor cells expands quickly, resulting in a high probability of several tens to several hundreds of cells with CSF3R truncation mutations; therapeutic granulocyte colony-stimulating factor (G-CSF) administration early in life exerts a strong selective pressure, providing mutants with a growth advantage. Applying population genetics theory, we propose a novel two-phase model of disease development from SCN to sMDS. In Phase 1, hematopoietic tissues expand and produce tens to hundreds of stem cells with the CSF3R truncation mutation. Phase 2 occurs postnatally through adult stages with bone marrow production of granulocyte precursors and positive selection of mutants due to chronic G-CSF therapy to reverse the severe neutropenia. We predict the existence of the pool of cells with the mutated truncated receptor before G-CSF treatment begins. The model does not require increase in mutation rate under G-CSF treatment and agrees with age distribution of sMDS onset and clinical sequencing data.

Cancer develops by multistep acquisition of mutations in a progenitor cell and its daughter cells. Severe congenital neutropenia (SCN) manifests itself through an inability to produce enough granulocytes to prevent infections. SCN commonly results from a germline ELANE mutation. Large doses of the blood growth factor granulocyte colony-stimulating factor (G-CSF) rescue granulocyte production. However, SCN frequently transforms to a myeloid malignancy, commonly associated with a somatic mutation in CSF3R, the gene encoding the G-CSF Receptor. We built a mathematical model of evolution for CSF3R mutation starting with bone marrow expansion at the fetal development stage and continuing with postnatal competition between normal and malignant bone marrow cells. We employ tools of probability theory such as multitype branching processes and Moran models modified to account for expansion of hematopoiesis during human development. With realistic coefficients, we obtain agreement with the age range at which malignancy arises in patients. In addition, our model predicts the existence of a pool of cells with mutated CSF3R before G-CSF treatment begins. Our findings may be clinically applied to intervene more effectively and selectively in SCN patients.

[Mitoxantrone-cytarabine-etoposide induction therapy in children with acute myeloid leukemia: a single-center study of complications and clinical outcomes]

OBJECTIVE

To investigate the complications and clinical outcome of children with acute myeloid leukemia (AML) undergoing mitoxantrone-cytarabine-etoposide (MAE) induction therapy.

METHODS

A total of 170 children with AML were given MAE induction therapy, and the complications and remission rate were analyzed after treatment.

RESULTS

The male/female ratio was 1.33:1 and the mean age was 7.4 years (range 1-15 years). Leukocyte count at diagnosis was 29.52×10⁹/L [range (0.77-351)×10⁹/L]. Of all children, 2 had M0-AML, 24 had M2-AML, 2 had M4-AML, 48 had M5-AML, 3 had M6-AML, 7 had M7-AML, 69 had AML with t(8;21)(q22;q22), and 15 had AML with inv(16)(p13.1q22) or t(16;16)(p13.1;q22). The most common complication was infection (158/170, 92.9%). Among these 158 patients, 22 (13.9%) had agranulocytosis with pyrexia (with no definite focus of infection), and 136 (86.1%) had definite focus of infection (including bloodstream infection). Other complications included non-infectious diarrhea, bleeding, and drug-induced hepatitis. Treatment-related mortality was observed in 10 children, among whom 8 had severe infection, 1 had multiple organ failure, and 1 had respiratory failure. Remission rate was evaluated for 156 children and the results showed a complete remission rate of 85.3%, a partial remission rate of 4.5%, and a non-remission rate of 10.3%.

CONCLUSIONS

Induction therapy with the MAE regimen helps to achieve a good remission rate in children with AML after one course of treatment. Infection is the main complication and a major cause of treatment-related mortality.

Differences in infection prophylaxis measures between paediatric acute myeloid leukaemia study groups within the international Berlin-Frankfürt-Münster (I-BFM) study group

Prevention of infections is of obvious relevance in paediatric patients with acute myeloid leukaemia (AML). However, recommendations are often non-specific and supported by low-quality evidence, resulting in divergent infection preventive regimens. Using a web-based survey, we investigated the infection prophylaxis guidelines of 22 paediatric AML study groups affiliated to the international Berlin-Frankfürt-Münster study group. In order to evaluate differences in daily practice among hospitals, representatives (n = 27) from the Nordic Society for Paediatric Haematology and Oncology-Dutch-Belgium-Hong Kong - AML study group participated in a slightly modified survey. Seven study groups (32%) advise gram-negative antibiotic prophylaxis, mainly with fluoroquinolones (n = 6). Gram-positive prophylaxis is prescribed by eight groups (36%). Over 60% of the study groups prescribe food and social restrictions, but the specific topics and strictness differ widely. According to the hospital-based survey, sites roughly comply with common study group guidelines. However, the use of any gram-negative antibiotic prophylaxis, the specific prophylactic antifungal agent and the strictness of the food and social restrictions differ substantially between the hospitals. Despite a long history of close collaboration, many differences are still present between the affiliated groups. The results of this survey provide an appropriate baseline measure to study the emergence and impact of future guidelines on infection prophylaxis in paediatric AML.

Clofarabine, high-dose cytarabine and liposomal daunorubicin in pediatric relapsed/refractory acute myeloid leukemia: a phase IB study

Survival in children with relapsed/refractory acute myeloid leukemia is unsatisfactory. Treatment consists of one course of fludarabine, cytarabine and liposomal daunorubicin, followed by fludarabine and cytarabine and stem-cell transplantation. Study ITCC 020/I-BFM 2009-02 aimed to identify the recommended phase II dose of clofarabine replacing fludarabine in the abovementioned combination regimen (3+3 design). Escalating dose levels of clofarabine (20-40 mg/m²/day × 5 days) and liposomal daunorubicin (40-80 mg/m²/day) were administered with cytarabine (2 g/m²/day × 5 days). Liposomal DNR was given on day 1, 3 and 5 only. The cohort at the recommended phase II dose was expanded to make a preliminary assessment of anti-leukemic activity. Thirty-four children were enrolled: refractory 1^st (n=11), early 1st (n=15), ≥2^nd relapse (n=8). Dose level 3 (30 mg/m²clofarabine; 60 mg/m²liposomal daunorubicin) appeared to be safe only in patients without subclinical fungal infections. Infectious complications were dose-limiting. The recommended phase II dose was 40 mg/m² clofarabine with 60 mg/m² liposomal daunorubicin. Side-effects mainly consisted of infections. The overall response rate was 68% in 31 response evaluable patients, and 80% at the recommended phase II dose (n=10); 22 patients proceeded to stem cell transplantation. The 2-year probability of event-free survival (pEFS) was 26.5±7.6 and probability of survival (pOS) 32.4±8.0%. In the 21 responding patients, the 2-year pEFS was 42.9±10.8 and pOS 47.6±10.9%. Clofarabine exposure in plasma was not significantly different from that in single-agent studies. In conclusion, clofarabine was well tolerated and showed high response rates in relapsed/refractory pediatric acute myeloid leukemia. Patients with (sub) clinical fungal infections should be treated with caution. Clofarabine has been taken forward in the Berlin-Frankfurt-Münster study for newly diagnosed acute myeloid leukemia. The Study ITCC-020 was registered as EUDRA-CT 2009-009457-13; Dutch Trial Registry number 1880.

Gain-of-function mutations in granulocyte colony-stimulating factor receptor (CSF3R) reveal distinct mechanisms of CSF3R activation

Granulocyte colony-stimulating factor (G-CSF or CSF3) and its receptor CSF3R regulate granulopoiesis, neutrophil function, and hematopoietic stem cell mobilization. Recent studies have uncovered an oncogenic role of mutations in the CSF3R gene in many hematologic malignancies. To find additional CSF3R mutations that give rise to cell transformation, we performed a cellular transformation assay in which murine interleukin 3 (IL-3)-dependent Ba/F3 cells were transduced with WT CSF3R plasmid and screened for spontaneous growth in the absence of IL-3. Any outgrowth clones were sequenced to identify CSF3R mutations with transformation capacity. We identified several novel mutations and determined that they transform cells via four distinct mechanisms: 1) cysteine- and disulfide bond-mediated dimerization (S581C); 2) polar, noncharged amino acid substitution at the transmembrane helix dimer interface at residue Thr-640; 3) increased internalization by a Glu-524 substitution that mimics a low G-CSF dose; and 4) hydrophobic amino acid substitutions in the membrane-proximal residues Thr-612, Thr-615, and Thr-618. Furthermore, the change in signaling activation was related to an altered CSF3R localization. We also found that CSF3R-induced STAT3 and ERK activations require CSF3R internalization, whereas STAT5 activation occurred at the cell surface. Cumulatively, we have expanded the regions of the CSF3R extracellular and transmembrane domains in which missense mutations exhibit leukemogenic capacity and have further elucidated the mechanistic underpinnings that underlie altered CSF3R expression, dimerization, and signaling activation.

miRNAs in acute myeloid leukemia

MicroRNAs (miRNAs) are small, non-coding RNAs found throughout the eukaryotes that control the expression of a number of genes involved in commitment and differentiation of hematopoietic stem cells and tumorigenesis. Widespread dysregulation of miRNAs have been found in hematological malignancies, including human acute myeloid leukemia (AML). A comprehensive understanding of the role of miRNAs within the complex regulatory networks that are disrupted in malignant AML cells is a prerequisite for the development of therapeutic strategies employing miRNA modulators. Herein, we review the roles of emerging miRNAs and the miRNAs regulatory networks in AML pathogenesis, prognosis, and miRNA-directed therapies.

Mathematical modeling of the impact of cytokine response of acute myeloid leukemia cells on patient prognosis

Acute myeloid leukemia (AML) is a heterogeneous disease. One reason for the heterogeneity may originate from inter-individual differences in the responses of leukemic cells to endogenous cytokines. On the basis of mathematical modeling, computer simulations and patient data, we have provided evidence that cytokine-independent leukemic cell proliferation may be linked to early relapses and poor overall survival. Depending whether the model of cytokine-dependent or cytokine-independent leukemic cell proliferation fits to the clinical data, patients can be assigned to two groups that differ significantly with respect to overall survival. The modeling approach further enables us to identify parameter constellations that can explain unexpected responses of some patients to external cytokines such as blast crisis or remission without chemotherapy.

Fludarabine, cytarabine, granulocyte colony-stimulating factor and idarubicin for relapsed childhood acute myeloid leukemia

BACKGROUND

The combination of fludarabine (Flu), high-dose cytarabine (Ara-C) and granulocyte colony-stimulating factor (G-CSF; FLAG), with anthracyclines has become standard chemotherapy for refractory acute myeloid leukemia (AML) in European children and adults. To clarify the efficacy and the safety of FLAG-idarubicin (IDA) for children prospectively, we planned a multicenter phase II study (AML-R11) by the Japanese Pediatric Leukemia/Lymphoma Study Group.

METHODS

Patients with AML aged between 2 and 20 years old, who had the first bone marrow (BM) relapse or induction failure, were enrolled. The FLAG-IDA regimen consisted of Flu 30 mg/m² for 5 days, Ara-C 2 g/m² for 5 days, G-CSF (lenograstim) 5 μg/kg for 6 days and IDA 10 mg/m² for 3 days. The primary endpoint was remission rate after therapy.

RESULTS

Due to drug supply issues, the trial was suspended after the inclusion of seven eligible patients. There were six cases of early relapse within 1 year of the first remission. All seven patients completed the therapy and no early death was observed. Hematological toxicity was common, and one patient developed grade 4 non-hematological toxicity of bacterial meningitis. Although only one patient with late relapse achieved complete remission, minimal residual disease was positive on both flow cytometry and Wilms' tumor 1 mRNA. Two patients were alive in remission following hematopoietic stem cell transplantation, whereas the other five patients died of either the disease or treatment-related causes.

CONCLUSION

FLAG-IDA might be tolerable for children with refractory AML although the efficacy should be further investigated.

Characterization of the leukemogenic potential of distal cytoplasmic CSF3R truncation and missense mutations

An increasing number of variants of unknown significance (VUS) are being identified in leukemia patients with the application of deep sequencing and these include CSF3R cytoplasmic mutations. Previous studies have demonstrated oncogenic potential of certain CSF3R truncation mutations prior to internalization motifs. However, the oncogenic potential of truncating the more distal region of CSF3R cytoplasmic domain as well as cytoplasmic missense mutations remains uncharacterized. Here we identified that CSF3R distal cytoplasmic truncation mutations (Q793–Q823) also harbored leukemogenic potential. Mechanistically, these distal cytoplasmic truncation mutations demonstrated markedly decreased receptor degradation, probably due to loss of the de-phosphorylation domain (residues N818–F836). Furthermore, all truncations prior to Q823 demonstrated increased expression of the higher molecular weight CSF3R band, which is shown to be essential for the receptor surface expression and the oncogenic potential. We further demonstrated that sufficient STAT5 activation is essential for oncogenic potential. In addition, CSF3R K704A demonstrated transforming capacity due to interruption of receptor ubiquitination and degradation. In summary, we have expanded the region of the CSF3R cytoplasmic domain in which truncation or missense mutations exhibit leukemogenic capacity, which will be useful for evaluating the relevance of CSF3R mutations in patients and helpful in defining targeted therapy strategies.

Purification of leukemic blast cells from blood smears using laser microdissection

In treatment of acute myeloid leukemia (AML), prognostic factors, including gene mutation and abnormal gene expression, enable risk stratification of patients. However, in the case of a small proportion of leukemic blast cells, such as AML associated with Down syndrome (AML-DS), it is not possible to examine prognostic factors precisely due to the large proportion of normal cells. Here, we present a novel method for examining prognostic factors by making a smear on a membrane slide glass from a small amount of diagnostic specimen and collecting highly pure leukemic blast cells by laser microdissection (LMD). We verified the effectiveness of this method using 10% KPAM1 cell line suspension and peripheral blood containing 20% blast cells obtained from a patient with transient abnormal myelopoiesis (TAM). After making blood smears, approximately 100 cells were collected and analyzed by direct sequencing. Frameshift mutations (2 bp deletion and 17 bp duplication, respectively) in GATA-1 were detected in each sample, suggesting KPAM1 and TAM blast cells were accurately purified. This novel method enables us to precisely examine prognostic factors in many cases, even in cases with a small proportion of leukemic blast cells or small specimens to preserve.

FLAG Regimen with or without Idarubicin in Children with Relapsed/Refractory Acute Leukemia: Experience from a Turkish Pediatric Hematology Center

Objective:

The optimal therapy to achieve higher rates of survival in pediatric relapsed/refractory acute leukemia (AL) is still unknown. In developing countries, it is difficult to obtain some of the recent drugs for optimal therapy and mostly well-known drugs proven to be effective are used. We assessed the efficacy of the combination of fludarabine, high-dose cytarabine, and granulocyte colony-stimulating factor (FLAG regimen) with or without idarubicin (IDA) in children with relapsed/refractory acute lymphoblastic leukemia and acute myeloid leukemia.

Materials and Methods:

Between September 2007 and May 2015, 18 children with refractory/relapsed AL attending our center, treated with a FLAG regimen with or without IDA, were included. The primary end point was the remission status of the bone marrow sampled after the first/second course of chemotherapy. The second end point was the duration of survival after hematopoietic stem cell transplantation (HSCT).

Results:

Complete remission (CR) was achieved in 7 patients (38.8%) after the first cycle, and at the end of the second cycle the total number of patients in CR was 8 (42.1%). All patients in CR underwent HSCT. The CR rate in patients who had IDA in combination therapy was 28.6%, and it was 50% in patients treated without IDA (p=0.36). Mean survival duration in transplanted patients was 24.7±20.8 months (minimum-maximum: 2-70, median: 25 months), and it was 2.7±1.64 months (minimum-maximum: 0-5, median: 3 months) in nontransplanted patients. Five of them (27.7%) were still alive at the end of the study and in CR. The median time of follow-up for these patients was 33 months (minimum-maximum: 25-70 months).

Conclusion:

FLAG regimens with or without IDA produced a CR of >24 months in 27.7% of children with relapsed/refractory AL and can be recommended as therapeutic options prior to HSCT in developing countries.

Strategies for reducing the treatment-related physical burden of childhood acute myeloid leukaemia - a review

Over the last four decades the survival of paediatric patients with acute myeloid leukaemia has gradually increased to 70% in high-income countries. The therapy is very intensive and associated with many acute and long-term side effects. The early death rate has been reduced to 1-4%. The acute toxicity is a limiting factor for improving survival in low-income countries. Transplant is associated with more endocrinological late effects while cardiotoxicity is more common after relapse. Reducing the physical costs of therapy without jeopardizing survival may be accomplished by optimal supportive care, less cardiotoxic anthracyclines, less consolidation courses and strict indications for stem cell transplantation. Analysing scenarios with different frequency of transplantation in first complete remission show similar overall survival rates, indicating that almost all patients can be spared the procedure in first remission. Reducing relapse risk is an effective way of reducing toxicity and more targeted therapy and improved risk group stratifications are needed.

Lack of Effectiveness of Neutropenic Diet and Social Restrictions as Anti-Infective Measures in Children With Acute Myeloid Leukemia: An Analysis of the AML-BFM 2004 Trial

PURPOSE

Although nonpharmacologic anti-infective measures are widely used in children treated for acute myeloid leukemia (AML), there is little evidence of their effectiveness.

PATIENTS AND METHODS

We analyzed infectious complications in children during intensive treatment of AML according to the AML-BFM 2004 trial and surveyed sites on institutional standards regarding recommended restrictions of social contacts (six items), pets (five items), and food (eight items). A scoring system was developed with a restriction score for each item. Multivariable Poisson regression adjusted for sex, age, weight group, risk stratification, and prophylactic antibiotics was used to estimate the impact of the restrictions on the incidence ratios of fever of unknown origin, bacteremia, pneumonia, and gastroenteritis.

RESULTS

Data on recommendations of nonpharmacologic anti-infective measures and infectious complications were available in 339 patients treated in 37 institutions. Analyses did not demonstrate a significant benefit of any of the restrictions regarding food, social contacts, and pets on the risk of fever, bacteremia, pneumonia, and gastroenteritis. In contrast, age, weight group, risk stratification, and nonabsorbable antibiotics had some influence on infections complications.

CONCLUSION

The lack of effectiveness of dietary restrictions and restrictions regarding social contacts and pets should result in reconsideration of anti-infective policies.

Collaborative Efforts Driving Progress in Pediatric Acute Myeloid Leukemia

Diagnosis, treatment, response monitoring, and outcome of pediatric acute myeloid leukemia (AML) have made enormous progress during the past decades. Because AML is a rare type of childhood cancer, with an incidence of approximately seven occurrences per 1 million children annually, national and international collaborative efforts have evolved. This overview describes these efforts and includes a summary of the history and contributions of each of the main collaborative pediatric AML groups worldwide. The focus is on translational and clinical research, which includes past, current, and future clinical trials. Separate sections concern acute promyelocytic leukemia, myeloid leukemia of Down syndrome, and relapsed AML. A plethora of novel antileukemic agents that have emerged, including new classes of drugs, are summarized as well. Finally, an important aspect of the treatment of pediatric AML--supportive care--and late effects are discussed. The future is bright, with a wide range of emerging innovative therapies and with more and more international collaboration that ultimately aim to cure all children with AML, with fewer adverse effects and without late effects.

miR-155 is associated with the leukemogenic potential of the class IV granulocyte colony-stimulating factor receptor in CD34⁺ progenitor cells

Granulocyte colony-stimulating factor (G-CSF) is a major regulator of granulopoiesis on engagement with the G-CSF receptor (G-CSFR). The truncated, alternatively spliced, class IV G-CSFR (G-CSFRIV) has been associated with defective differentiation and relapse risk in pediatric acute myeloid leukemia (AML) patients. However, the detailed biological properties of G-CSFRIV in human CD34(+) hematopoietic stem and progenitor cells (HSPCs) and the potential leukemogenic mechanism of this receptor remain poorly understood. In the present study, we observed that G-CSFRIV-overexpressing (G-CSFRIV(+)) HSPCs demonstrated an enhanced proliferative and survival capacity on G-CSF stimulation. Cell cycle analyses showed a higher frequency of G-CSFRIV(+) cells in the S and G2/M phase. Also, apoptosis rates were significantly lower in G-CSFRIV(+) HSPCs. These findings were shown to be associated with a sustained Stat5 activation and elevated miR-155 expression. In addition, G-CSF showed to further induce G-CSFRIV and miR-155 expression of peripheral blood mononuclear cells isolated from AML patients. A Stat5 pharmacological inhibitor or ribonucleic acid (RNA) interference-mediated silencing of the expression of miR-155 abrogated the aberrant proliferative capacity of the G-CSFRIV(+) HSPCs. Hence, the dysregulation of Stat5/miR-155 pathway in the G-CSFRIV(+) HSPCs supports their leukemogenic potential. Specific miRNA silencing or the inhibition of Stat5-associated pathways might contribute to preventing the risk of leukemogenesis in G-CSFRIV(+) HSPCs. This study may promote the development of a personalized effective antileukemia therapy, in particular for the patients exhibiting higher expression levels of G-CSFRIV, and further highlights the necessity of pre-screening the patients for G-CSFR isoforms expression patterns before G-CSF administration.

Anti-infective prophylaxis in pediatric patients with acute myeloid leukemia

Pediatric patients undergoing treatment for acute myeloid leukemia (AML) are at high risk for infectious complications, predominantly due to Gram-negative bacteria, viridans group streptococci and fungal pathogens. In order to prevent infections in these patients, most institutions have implemented a number of non-pharmacological approaches to supportive care. In addition, antibiotic prophylaxis reduces bacterial infection, but may increase the emergence of resistance. Antifungal prophylaxis is generally recommended for children with AML. Whereas the use of hematopoietic growth factors has not resulted in improved survival, the efficacy of prophylactic granulocyte transfusions has to be determined.

Use of G-CSF to hasten neutrophil recovery after auto-SCT for AML is not associated with increased relapse incidence: a report from the Acute Leukemia Working Party of the EBMT

Application of G-CSF in AML is controversial as leukemic blasts may express receptors interacting with the cytokine, which may stimulate leukemia growth. We retrospectively analyzed the impact of G-CSF use to accelerate neutrophil recovery after auto-SCT on outcome. Adults with AML in first CR autografted between 1994 and 2010 were included. Nine hundred and seventy two patients were treated with G-CSF after auto-SCT whereas 1121 were not. BM and PB were used as a source of stem cells in 454 (22%) and 1639 (78%) cases, respectively. The incidence of relapse at 5 years in the BM-auto-SCT group was 38% for patients receiving post-transplant G-CSF and 43% for those not treated with G-CSF, P=0.46. In the PB-auto-SCT cohort, respective probabilities were 48% and 49%, P=0.49. No impact of the use of G-CSF could be demonstrated with respect to the probability of leukemia-free survival: in the BM-auto-SCT group, 51% for G-CSF(+) and 48% for G-CSF(-), P=0.73; in PB-auto-SCT group, 42% for G-CSF(+) and 43% for G-CSF(-), P=0.83. Although G-CSF administration significantly shortened the neutropenic phase, no beneficial effect was observed with regard to non-relapse mortality. In patients with AML, the use of G-CSF after auto-SCT is not associated with increased risk of relapse irrespective of the source of stem cells used.

Alternatively spliced, truncated GCSF receptor promotes leukemogenic properties and sensitivity to JAK inhibition

Granulocyte colony-stimulating factor (GCSF) drives the production of myeloid progenitor and precursor cells toward neutrophils via the GCSF receptor (GCSFR, gene name CSF3R). Children with severe congenital neutropenia chronically receive pharmacologic doses of GCSF, and ∼30% will develop myelodysplasia/acute myeloid leukemia (AML) associated with GCSFR truncation mutations. In addition to mutations, multiple isoforms of CSF3R have also been reported. We found elevated expression of the alternatively spliced isoform, class IV CSF3R in adult myelodysplastic syndrome/AML patients. Aside from its association with monosomy 7 and higher rates of relapse in pediatric AML patients, little is known about the biology of the class IV isoform. We found developmental regulation of CSF3R isoforms with the class IV expression more representative of a progenitor cell stage. Striking differences were found in phosphoprotein signaling involving Janus kinase (JAK)-signal transducer and activator of transcription (STAT) and cell cycle gene expression. Enhanced proliferation by class IV GCSFR was associated with diminished STAT3 and STAT5 activation, yet showed sensitivity to JAK2 inhibitors. Alterations in the C-terminal domain of the GCSFR result in leukemic properties of enhanced growth, impaired differentiation and resistance to apoptosis, suggesting that they can behave as oncogenic drivers, sensitive to JAK2 inhibition.

Appropriate dose reduction in induction therapy is essential for the treatment of infants with acute myeloid leukemia: a report from the Japanese Pediatric Leukemia/Lymphoma Study Group

Infants (<1 year old) with acute myeloid leukemia (AML) are particularly vulnerable to intensive cytotoxic therapy. Indeed, the mortality rate was high among infants enrolled in the Japanese Pediatric Leukemia/Lymphoma Study Group AML-05 study, which prompted us to temporarily suspend patient enrollment and amend the protocol. Forty-five infants with AML were enrolled. For patients aged <2 years, drug doses were adjusted for body weight. Following the protocol amendments, doses for infants were reduced by a further 33 % in the initial induction course. Six infants died during the induction phase (including five early deaths), mainly due to pulmonary complications. The 3-year probability of overall survival (pOS) in all 45 infants [55.9 %, 95 % confidence interval (CI) 37.9-70.6 %] was significantly lower than that of patients aged 1 to <2 years (77.0 %, 95 % CI 62.7-86.3 %) and those aged ≥2 years (74.7 %, 95 % CI 69.2-79.4 %) (P = 0.037), mainly due to the higher non-relapse mortality rate in infants. No early deaths occurred after the protocol amendments, and the 3-year pOS of the 17 infants enrolled thereafter was 76.4 % (95 % CI 48.8-90.4 %). In conclusion, appropriate dose reduction is essential to avoid early deaths when treating infants with AML.

Effectiveness of supportive care measures to reduce infections in pediatric AML: a report from the Children's Oncology Group

Objective was to describe the effect of antibiotic and granulocyte colony-stimulating factor (G-CSF) prophylaxis and discharge policy on infection risk and nonrelapse-related mortality (NRM) during chemotherapy for children with acute myeloid leukemia. Patients were non-Down syndrome children enrolled on Children's Oncology Group (COG) trial AAML0531. We surveyed sites to determine institutional standards for systemic antibacterial, antifungal, and G-CSF prophylaxis, and mandatory hospitalization during neutropenia. COG institution survey response rate was 180 of 216 (83.3%). Of 1024 patients enrolled on AAML0531, 897 were non-Down patients from survey-responding institutions. In multiple regression, antibacterial prophylaxis reduced any sterile-site bacterial infection (incidence rate ratio [IRR] 0.85; 95% confidence interval [CI], 0.72-1.01; P = .058) and Gram-positive sterile-site infection (IRR 0.71; 95% CI, 0.57-0.90; P = .004). Prophylactic G-CSF reduced bacterial (IRR 0.79; 95% CI, 0.67-0.92; P = .004) and Clostridium difficile infections (CDIs; IRR 0.46; 95% CI, 0.25-0.84; P = .012). Mandatory hospitalization did not reduce bacterial/fungal infection or significantly reduce NRM but did increase CDI (IRR 1.96; 95% CI, 1.34-2.87; P < .001). Antibacterial and G-CSF prophylaxis reduced infection rates while mandatory hospitalization did not reduce infection or significantly affect NRM. This trial was registered at www.clinicaltrials.gov as #AAML0531.

FACS analysis of Stat3/5 signaling reveals sensitivity to G-CSF and IL-6 as a significant prognostic factor in pediatric AML: a Children's Oncology Group report

Signal transducer and activator of transcription 3 (Stat3) and Stat5 are critical signaling intermediates that promote survival in myeloid leukemias. We examined Stat3 and Stat5 activation patterns in resting and ligand-stimulated primary samples from pediatric patients with acute myeloid leukemia. Phosphorylated Stats were measured by FACS before and after stimulation with increasing doses of granulocyte-colony stimulating factor or IL-6. We also measured positive and negative regulators of Stat signaling, and we compared the variation in multiple parameters to identify biologic relationships. Levels of constitutively phosphorylated Stats were variable and did not correlate with survival. In terms of induced phospho-Stats, 15 of 139 specimens (11%) phosphorylated Stat3 in response to moderate doses of both granulocyte-colony stimulating factor and IL-6. Compared with groups that were resistant to 1 or both ligands, this pattern of dual sensitivity was associated with a superior outcome, with a 5-year event-free survival of 79% (P = .049) and 5-year overall survival of 100% (P = .006). This study provides important and novel insights into the biology of Stat3 and Stat5 signaling in acute myeloid leukemia. Patterns of ligand sensitivity may be valuable for improving risk identification, and for developing new agents for individualized therapy.

Diagnosis and management of acute myeloid leukemia in children and adolescents: recommendations from an international expert panel

Despite major improvements in outcome over the past decades, acute myeloid leukemia (AML) remains a life-threatening malignancy in children, with current survival rates of ∼70%. State-of-the-art recommendations in adult AML have recently been published in this journal by Döhner et al. The primary goal of an international expert panel of the International BFM Study Group AML Committee was to set standards for the management, diagnosis, response assessment, and treatment in childhood AML. This paper aims to discuss differences between childhood and adult AML, and to highlight recommendations that are specific to children. The particular relevance of new diagnostic and prognostic molecular markers in pediatric AML is presented. The general management of pediatric AML, the management of specific pediatric AML cohorts (such as infants) or subtypes of the disease occurring in children (such as Down syndrome related AML), as well as new therapeutic approaches, and the role of supportive care are discussed.

Challenging issues in pediatric oncology

Improvements in protocol-driven clinical trials and supportive care for children and adolescents with cancer have reduced mortality rates by more than 50% over the past three decades. Overall, the 5-year survival rate for patients with pediatric cancer has increased to approximately 80%. Recognition of the biological heterogeneity within specific subtypes of cancer, the discovery of genetic lesions that drive malignant transformation and cancer progression, and improved understanding of the basis of drug resistance will undoubtedly catalyze further advances in risk-directed treatments and the development of targeted therapies, boosting the cure rates further. Emerging new treatments include novel formulations of existing chemotherapeutic agents, monoclonal antibodies against cancer-associated antigens, and molecular therapies that target genetic lesions and their associated signaling pathways. Recent findings that link pharmacogenomic variations with drug exposure, adverse effects, and efficacy should accelerate efforts to develop personalized therapy for individual patients. Finally, palliative care should be included as an essential part of cancer management to prevent and relieve the suffering and to improve the quality of life of patients and their families.

Randomized trial of 2 dosages of prophylactic granulocyte-colony-stimulating factor after induction chemotherapy in pediatric acute myeloid leukemia

BACKGROUND

Granulocyte-colony-stimulating factor (G-CSF) is effective in accelerating neutrophil recovery after intensive chemotherapy for acute myeloid leukemia (AML). However, the optimal G-CSF dosage for patients with AML has not been determined. To the authors' knowledge, G-CSF dosages have not been compared in a randomized AML study.

METHODS

Patients who were enrolled on the St. Jude AML97 protocol and remained on study after window therapy were eligible to participate. The effect of the dosage of G-CSF given after induction chemotherapy Courses 1 and 2 was analyzed in 46 patients who were assigned randomly in a double-blinded manner to receive either 5 μg/kg daily or 10 μg/kg daily of G-CSF. The number of days of G-CSF treatment, neutropenia (an absolute neutrophil count <0.5 × 10(9) /L), and hospitalization; the number of episodes of febrile neutropenia, grade 2 through 4 infection, and antimicrobial therapy; transfusion requirements; the cost of supportive care; and survival were compared between the 2 study arms.

RESULTS

No statistically significant differences were observed between the 2 arms in any of the endpoints measured.

CONCLUSIONS

The higher G-CSF dosage (10 μg/kg daily) offered no greater benefit than the lower dosage (5 μg/kg daily) in patients who were receiving intensive chemotherapy for AML.

Ewing's Sarcoma and Second Malignancies

Ewing's sarcoma (ES) is a rare tumor that is most common in children and young adults. Late effects of ES therapy include second cancers, a tragic outcome for survivors of such a young age. This paper will explore the frequencies and types of malignancies that occur after ES. Additionally, it will review how second malignancies have changed with the shift in treatment from high-dose radiation to chemotherapy regimens including alkylators and epipodophyllotoxins. The risk of additional cancers in ES survivors will also be compared to survivors of other childhood cancers. Finally, the possible genetic contribution to ES and second malignancies will be discussed.

G-CSF and its receptor in myeloid malignancy

Granulocyte colony-stimulating factor (G-CSF) has been used in the clinic for more than 2 decades to treat congenital and acquired neutropenias and to reduce febrile neutropenia before or during courses of intensive cytoreductive therapy. In addition, healthy stem cell donors receive short-term treatment with G-CSF for mobilization of hematopoietic stem cells. G-CSF has also been applied in priming strategies designed to enhance the sensitivity of leukemia stem cells to cytotoxic agents, in protocols aimed to induce their differentiation and accompanying growth arrest and cell death, and in severe aplastic anemia and myelodysplastic syndrome (MDS) to alleviate anemia. The potential adverse effects of G-CSF administration, particularly the risk of malignant transformation, have fueled ongoing debates, some of which can only be settled in follow-up studies extending over several decades. This specifically applies to children with severe congenital neutropenia who receive lifelong treatment with G-CSF and in which the high susceptibility to develop MDS and acute myeloid leukemia (AML) has now become a major clinical concern. Here, we will highlight some of the controversies and challenges regarding the clinical application of G-CSF and discuss a possible role of G-CSF in malignant transformation, particularly in patients with neutropenia harboring mutations in the gene encoding the G-CSF receptor.