Bone-marrow relapse in paediatric acute lymphoblastic leukaemia

Survival outcomes in patients with relapsed/refractory or MRD-positive B-cell acute lymphoblastic leukemia treated with blinatumomab

Blinatumomab has demonstrated significant efficacy in adult and pediatric patients with relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-cell ALL) and patients with measurable residual disease (MRD). This review aimed to compare median relapse-free survival (RFS) and median overall survival (OS) in adult and pediatric patients with R/R or MRD-positive B-cell ALL from pivotal studies [MT-103-211 and TOWER for adults with Philadelphia chromosome (Ph)-negative R/R B-cell ALL, ALCANTARA for adults with Ph-positive R/R B-cell ALL, MT-103-203 for adults with MRD-positive B-cell ALL, and MT-103-205 for pediatric patients with R/R B-cell ALL], with the median RFS and OS from retrospective analyses, country or ethnicity-specific studies, and studies based on real-world evidence (RWE) identified from a literature search. Adults with Ph-negative R/R B-cell ALL who received blinatumomab as first salvage demonstrated a numerically longer median OS compared with that in patients from pivotal studies (MT-103-211 and TOWER) without additional safety concerns. In pediatric patients with R/R B-cell ALL treated with blinatumomab, the median RFS and OS from retrospective analyses and country/ethnicity-specific studies were comparable with the median RFS and OS from the pivotal study MT-103-205. The median RFS and OS from RWE studies in adults with R/R B-cell ALL were numerically longer than the median RFS and OS from pivotal studies (MT-103-211, TOWER, and ALCANTARA); however, this trend was not observed in pediatric patients with R/R B-cell ALL. In conclusion, this analysis identified first salvage adults with Ph-negative R/R B-cell ALL as particularly well-suited for treatment with blinatumomab since survival outcomes from retrospective analyses reported in this patient subgroup were numerically better compared with those from pivotal studies without additional safety signals.

The current treatment approach to adolescents and young adults with acute lymphoblastic leukemia (AYA-ALL): challenges and considerations

INTRODUCTION

AYA-ALL differs from pediatric ALL in terms of clinical, biological, psychosocial factors and access to care and has an inferior outcome. It is now being recognized that pediatric-inspired protocols are superior to adult protocols for this cohort, but given the lack of randomized trials, several questions remain unanswered.

AREAS COVERED

In this review, we discuss how AYA-ALL is different from the pediatric ALL population, compare AYA ALL with ALL in middle and older age adults, review the studies that have enrolled the AYA cohort, summarize risk-stratified and response-adapted approaches, describe the biological subtypes, and review the novel agents/approaches under evaluation.

EXPERT OPINION

AYA-ALL is a complex and challenging disease that needs multidisciplinary and focused care. Well-designed clinical trials that focus on this cohort are needed to further improve the outcomes.

Temporal changes in incidence of relapse and outcome after relapse of childhood acute lymphoblastic leukemia over three decades; a Nordic population-based cohort study

Relapse remains the main obstacle to curing childhood acute lymphoblastic leukemia (ALL). The aims of this study were to compare incidence of relapse, prognostic factors, and survival after relapse between three consecutive Nordic Society of Pediatric Hematology and Oncology trials. Relapse occurred as a primary event in 638 of 4 458 children (1.0-14.9 years) diagnosed with Ph-negative ALL between 1992 and 2018. The 5-year cumulative incidence of relapse was 17.3% (95% CI 15.4-19.2%) and 16.5% (95% CI 14.3-18.8%) for patients in the ALL1992 and ALL2000 trials, respectively, but decreased to 8.4% (95% CI 7.0-10.1%) for patients in the ALL2008 trial. No changes in duration of first complete remission and site of relapse were observed over time; however, high hyperdiploidy, and t(12;21) decreased in the ALL2008 trial. The 4-year overall survival after relapse was 56.6% (95% CI 52.5-60.5%) and no statistically significant temporal improvements were observed. Age ≥10 years, T-cell immunophenotype, bone-marrow involvement, early and very early relapse, hypodiploidy, and Down syndrome all independently predicted worse outcome after relapse. Improvements in the primary treatment of childhood ALL has resulted in fewer relapses. However, failure to improve outcome of remaining relapses suggests a selection of harder-to-cure relapses and calls for new therapeutic strategies.

Novel Treatments for Pediatric Relapsed or Refractory Acute B-Cell Lineage Lymphoblastic Leukemia: Precision Medicine Era

With the markedly increased cure rate for children with newly diagnosed pediatric B-cell acute lymphoblastic leukemia (B-ALL), relapse and refractory B-ALL (R/R B-ALL) remain the primary cause of death worldwide due to the limitations of multidrug chemotherapy. As we now have a more profound understanding of R/R ALL, including the mechanism of recurrence and drug resistance, prognostic indicators, genotypic changes and so on, we can use newly emerging technologies to identify operational molecular targets and find sensitive drugs for individualized treatment. In addition, more promising and innovative immunotherapies and molecular targeted drugs that are expected to kill leukemic cells more effectively while maintaining low toxicity to achieve minimal residual disease (MRD) negativity and better bridge hematopoietic stem cell transplantation (HSCT) have also been widely developed. To date, the prognosis of pediatric patients with R/R B-ALL has been enhanced markedly thanks to the development of novel drugs. This article reviews the new advancements of several promising strategies for pediatric R/R B-ALL.

Sensitization to Drug Treatment in Precursor B-Cell Acute Lymphoblastic Leukemia Is Not Achieved by Stromal NF-κB Inhibition of Cell Adhesion but by Stromal PKC-Dependent Inhibition of ABC Transporters Activity

Cell adhesion to stromal support and the associated intracellular signaling are central to drug resistance, therefore blocking both has been effective in increasing drug sensitization in leukemia. The stromal Ser/Thr protein kinase C (PKC) has been found to be important for conferring protection to leukemic cells. We aimed at elucidating the intracellular signals connected to cell adhesion and to stromal PKC. We found that NF-κB and Akt were up-regulated in mesenchymal stem cells (MSC) after binding of B-cell acute lymphoblastic leukemia (B-ALL) cells. Nevertheless, Akt inhibition did not induce B-ALL cell detachment. In spite of a clear activation of the NF-κB signaling pathway after B-ALL cell binding (up-regulation NF-κB1/2, and down-regulation of the IKBε and IKBα inhibitors) and an important reduction in cell adhesion after NF-κB inhibition, sensitization to the drug treatment was not observed. This was opposite to the PKC inhibitors Enzastaurin and HKPS, a novel chimeric peptide inhibitor, that were able to increase sensitization to dexamethasone, methotrexate, and vincristine. PLCγ1, Erk1/2, and CREB appear to be related to PKC signaling and PKC effect on drug sensitization since they were contra-regulated by HKPS when compared to dexamethasone-treated cells. Additionally, PKC inhibition by HKPS, but not by Enzastaurin, in MSC reduced the activity of three ABC transporters in leukemic cells treated with dexamethasone, a new indirect mechanism to increase sensitization to drug treatment in B-ALL cells. Our results show the validity of targeting the functional characteristic acquired and modulated during cell-to-cell interactions occurring in the leukemic niche.

The Role of Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) offers potentially curative treatment for many children with high-risk or relapsed acute leukemia (AL), thanks to the combination of intense preparative radio/chemotherapy and the graft-versus-leukemia (GvL) effect. Over the years, progress in high-resolution donor typing, choice of conditioning regimen, graft-versus-host disease (GvHD) prophylaxis and supportive care measures have continuously improved overall transplant outcome, and recent successes using alternative donors have extended the potential application of allotransplantation to most patients. In addition, the importance of minimal residual disease (MRD) before and after transplantation is being increasingly clarified and MRD-directed interventions may be employed to further ameliorate leukemia-free survival after allogeneic HSCT. These advances have occurred in parallel with continuous refinements in chemotherapy protocols and the development of targeted therapies, which may redefine the indications for HSCT in the coming years. This review discusses the role of HSCT in childhood AL by analysing transplant indications in both acute lymphoblastic and acute myeloid leukemia, together with current and most promising strategies to further improve transplant outcome, including optimization of conditioning regimen and MRD-directed interventions.

Leukemia-Induced Cellular Senescence and Stemness Alterations in Mesenchymal Stem Cells Are Reversible upon Withdrawal of B-Cell Acute Lymphoblastic Leukemia Cells

Leukemic cell growth in the bone marrow (BM) induces a very stressful condition. Mesenchymal stem cells (MSC), a key component of this BM niche, are affected in several ways with unfavorable consequences on hematopoietic stem cells favoring leukemic cells. These alterations in MSC during B-cell acute lymphoblastic leukemia (B-ALL) have not been fully studied. In this work, we have compared the modifications that occur in an in vitro leukemic niche (LN) with those observed in MSC isolated from B-ALL patients. MSC in this LN niche showed features of a senescence process, i.e., altered morphology, increased senescence-associated β-Galactosidase (SA-βGAL) activity, and upregulation of p53 and p21 (without p16 expression), cell-cycle arrest, reduced clonogenicity, and some moderated changes in stemness properties. Importantly, almost all of these features were found in MSC isolated from B-ALL patients. These alterations rendered B-ALL cells susceptible to the chemotherapeutic agent dexamethasone. The senescent process seems to be transient since when leukemic cells are removed, normal MSC morphology is re-established, SA-βGAL expression is diminished, and MSC are capable of re-entering cell cycle. In addition, few cells showed low γH2AX phosphorylation that was reduced to basal levels upon cultivation. The reversibility of the senescent process in MSC must impinge important biological and clinical significance depending on cell interactions in the bone marrow at different stages of disease progression in B-ALL.

Improving and Maintaining Responses in Pediatric B-Cell Acute Lymphoblastic Leukemia Chimeric Antigen Receptor-T Cell Therapy

ABSTRACT

Chimeric antigen receptor T therapy has heralded a new era in the treatment of acute lymphoblastic leukemia (ALL) and other hematologic malignancies. In this autologous immunotherapy, patient-derived T cells are genetically engineered and then infused back to kill the leukemia cells. The observed response rates in ALL are a testament to the success of this therapy. However, there have been instances where the patients either did not respond or relapsed after initial response. Emergence of resistance due to antigen loss and T-cell exhaustion has been observed. This poses a challenge in making this therapy successful for every ALL patient and warrants deeper understanding of emergence of resistance and potential approaches to overcome them. Here we discuss current perspectives and advances in this area.

Frequency and Correlation of Common Genes Copy Number Alterations in Childhood Acute Lymphoblastic Leukemia with Prognosis

Objective:

It was shown by genomic profiling that despite no detectable chromosomal abnormalities a proportion of children with pre-B acute lymphoblastic leukemia harbors copy number alterations (CNA) of genes playing role in B-cell development and function. The aim of the study was to determine the frequency of CNA in pediatric acute lymphoblastic leukemia and correlate these findings with clinical outcome.

Methods:

DNA extracted from peripheral blood or bone marrow at diagnosis/relapse of fifty newly diagnosed children with precursor B-cell acute lymphoblastic leukemia was analyzed for CNA with multiplex ligation-dependent probe amplification.

Results:

The analysis revealed 76 CNA in 24 patients most frequently found in PAR1 (17%), CDKN2A/B (15.7%) and PAX5 (14.4%) genes. There were significant CNA co-occurrences between PAX5, CDKN2A/B, BTG1, ETV6, PAR1 or XP22 genes, (p<0.020) and the high-risk group. There was a significant correlation between EBF1, RB1, and IKZF1 alterations and bone marrow relapse. Patients with CNA in screened genes are more likely to succumb to their disease except for those with PAR1 or XP22 genes (p<0.050).

Conclusion:

The multiplex ligation-dependent probe amplification could be considered as an independent diagnostic tool allowing prompt identification of patients at high risk of treatment failure and, subsequently, a more adequate treatment approach.

Chimeric antigen receptor T cell therapy for pediatric and young adult B cell acute lymphoblastic leukemia

INTRODUCTION

Though 85% of children and young adults with acute lymphoblastic leukemia (ALL) are cured, until recently, the prognosis of relapsed or refractory disease has been dismal. The advent of chimeric antigen receptor (CAR) T-cell therapy has transformed the treatment of relapsed/refractory ALL. The most well-studied, successful CARs are autologous, murine-based anti-CD19 CARs, but new constructs are currently under clinical investigation.

AREAS COVERED

This review describes the history and design of CAR T cells, clinical trial outcomes of anti-CD19 and newer CARs, treatment-related toxicities including cytokine release syndrome and neurotoxicity, and issues with resistance and relapse. A search of PubMed and clinicaltrials.gov spanning from 2012-present was used to select original reports investigating the use of CAR T in pediatric patients.

EXPERT OPINION

CD19-targeted CARs have demonstrated remarkable response rates and produced durable remissions in very high-risk pediatric patient populations. The therapies, however, are limited by unique treatment-related toxicities and considerable rates of antigen-positive and antigen-negative relapses. Current research efforts focused on elucidating mechanisms of resistance/relapse and on developing strategies to prevent and treat relapse are critical to optimizing the use of CAR-T. In addition, ongoing trials testing CARs earlier in therapy and for new indications are key to informing their widespread usage.

Hematopoietic Stem Cell Transplantation in Pediatric Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

The remarkable improvement in the prognosis of children with acute lymphoblastic leukemia (ALL) has been mainly achieved through the administration of risk-adapted therapy, including allogeneic hematopoietic stem cell transplantation (HSCT). This paper reviews the current indications to HSCT in ALL children, as well as the type of donor and conditioning regimens commonly used. Finally, it will focus on future challenges in immunotherapy.

RECENT FINDINGS

As our comprehension of disease-specific risk factors improves, indications to HSCT continue to evolve. Future studies will answer the year-old question on the best conditioning regimen to be used in this setting, while a recent randomized controlled study fixed the optimal anti-thymocyte globulin dose in unrelated donor HSCT. HSCT, the oldest immunotherapy used in clinical practice, still represents the gold standard consolidation treatment for a number of pediatric patients with high-risk/relapsed ALL. New immunotherapies hold the promise of further improving outcomes in this setting.

Dual Targeting of Stromal Cell Support and Leukemic Cell Growth by a Peptidic PKC Inhibitor Shows Effectiveness against B-ALL

Mesenchymal stem cells (MSC) favour a scenario where leukemic cells survive. The protein kinase C (PKC) is essential to confer MSC support to leukemic cells and may be responsible for the intrinsic leukemic cell growth. Here we have evaluated the capacity of a chimeric peptide (HKPS), directed against classical PKC isoforms, to inhibit leukemic cell growth. HKPS was able to strongly inhibit viability of different leukemic cell lines, while control HK and PS peptides had no effect. Further testing showed that 30% of primary samples from paediatric B-cell acute lymphoblastic leukaemia (B-ALL) were also strongly affected by HKPS. We showed that HKPS disrupted the supportive effect of MSC that promote leukemic cell survival. Interestingly, ICAM-1 and VLA-5 expression increased in MSC during the co-cultures with B-ALL cells, and we found that HKPS inhibited the interaction between MSC and B-ALL cells due to a reduction in the expression of these adhesion molecules. Of note, the susceptibility of B-ALL cells to dexamethasone increased when MSC were treated with HKPS. These results show the relevance of these molecular interactions in the leukemic niche. The use of HKPS may be a new strategy to disrupt intercellular communications, increasing susceptibility to therapy, and at the same time, directly affecting the growth of PKC-dependent leukemic cells.

Utility of BMI-1 and NANOG expression levels in survival prediction of pediatric acute lymphoblastic leukemia

Background

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children characterized by the overproduction and accumulation of immature lymphoid cells in the bone marrow and peripheral blood. The BMI-1 is an important component of the Polycomb Repressive Complex-1 (PRC1). It is an important molecule for the self-renewal of hematopoietic stem cells (HSCs). The BMI-1 expression is generally high in HSCs and decreases after cell differentiation. The BMI-1 is required for the maintenance of normal and cancer stem cells and has been reported as an oncogene in various tumors. The NANOG is a homeodomain transcription factor responsible for maintaining the stem cell compartment at the blastocyst stage of developing embryos. The NANOG gene has been proven to be transcribed in CD34+ cells and different leukemic cells.

Methods

The ribonucleic acid (RNA) was extracted from the peripheral blood mononuclear cells (PBMNCs) of 30 pediatric ALL patients (16 B-ALL and 14 T-ALL) and 14 healthy controls. The Bmi-1 and NANOG expression levels were determined using the quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR).

Results

Compared to normal controls, patients with ALL exhibited upregulated levels of Bmi-1 (p = 0.03). Patients who overexpressed Bmi-1 and NANOG displayed a significantly worse survival than low-expressing patients (hazard ratio (HR) 5.74, 95% confidence interval (CI):1.48–22, p = 0.012 and HR 3.8, 95% CI:1.009–14.3, p = 0.048, respectively).

Conclusions

Taken together, these data suggest that the Bmi-1 and NANOG might serve as a novel survival predictor in ALL patients. Our observation also suggests that the Bmi-1 and NANOG could serve as new therapeutic targets for treatment of pediatric ALL.

The European Medicines Agency Review of Kymriah (Tisagenlecleucel) for the Treatment of Acute Lymphoblastic Leukemia and Diffuse Large B-Cell Lymphoma

Chimeric antigen receptor (CAR)-engineered T-cell therapy is becoming one of the most promising approaches in the treatment of cancer. On June 28, 2018, the Committee for Advanced Therapies (CAT) and the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Kymriah for pediatric and young adult patients up to 25 years of age with B-cell acute lymphoblastic leukemia (ALL) that is refractory, in relapse after transplant, or in second or later relapse and for adult patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) after two or more lines of systemic therapy. Kymriah became one of the first European Union-approved CAR T therapies. The active substance of Kymriah is tisagenlecleucel, an autologous, immunocellular cancer therapy that involves reprogramming the patient's own T cells to identify and eliminate CD19-expressing cells. This is achieved by addition of a transgene encoding a CAR. The benefit of Kymriah was its ability to achieve remission with a significant duration in patients with ALL and an objective response with a significant duration in patients with DLBCL. The most common hematological toxicity was cytopenia in both patients with ALL and those with DLBCL. Nonhematological side effects in patients with ALL were cytokine release syndrome (CRS), infections, secondary hypogammaglobulinemia due to B-cell aplasia, pyrexia, and decreased appetite. The most common nonhematological side effects in patients with DLBCL were CRS, infections, pyrexia, diarrhea, nausea, hypotension, and fatigue. Kymriah also received an orphan designation on April 29, 2014, following a positive recommendation by the Committee for Orphan Medicinal Products (COMP). Maintenance of the orphan designation was recommended at the time of marketing authorization as the COMP considered the product was of significant benefit for patients with both conditions. IMPLICATIONS FOR PRACTICE: Chimeric antigen receptor (CAR)-engineered T-cell therapy is becoming the most promising approach in cancer treatment, involving reprogramming the patient's own T cells with a CAR-encoding transgene to identify and eliminate cancer-specific surface antigen-expressing cells. On June 28, 2018, Kymriah became one of the first EMA approved CAR T therapies. CAR T technology seems highly promising for diseases with single genetic/protein alterations; however, for more complex diseases there will be challenges to target clonal variability within the tumor type or clonal evolution during disease progression. Products with a lesser toxicity profile or more risk-minimization tools are also anticipated.

The potential of CAR T therapy for relapsed or refractory pediatric and young adult B-cell ALL

Recent advancements in immunooncology have resulted in the generation of novel therapies such as chimeric antigen receptor (CAR) T cells, which have revolutionized the treatment of pediatric patients with relapsed or refractory B-cell acute lymphoblastic leukemia. The journey of tisagenlecleucel (formerly CTL019) from early preclinical success to the US Food and Drug Administration approval is summarized in this review. Strategies that are currently being investigated to improve the efficacy and safety profile of CAR T-cells are also explored, as well as the factors contributing to the present state of patient access to CAR T therapy.

Clinical characteristics and prognosis of pediatric patients with B cell acute lymphoblastic leukemia relapse

The aim of the present study was to investigate the clinical characteristics and prognosis of pediatric patients with B cell acute lymphoblastic leukemia (B-ALL) relapse. A total of 390 pediatric patients diagnosed as B-ALL and receiving regular chemotherapy in Jining First People's Hospital from August 2010 to May 2016 were selected. The clinical characteristics, therapeutic response and prognosis were compared between the two groups. There were significant differences in the comparisons of age, leukocyte count in the initial diagnosis and glucocorticoid sensitive test between B-cell ALL (B-ALL) relapse group and non-relapse group; the minimal residual disease (MRD) levels of pediatric patients in the two groups at 33 days and 12 weeks were significantly different. The 3-year event-free survival (EFS) rates of pediatric patients with early, medium and late B-ALL relapse were 12.5±7.8%, 33.1±9.8% and 63.6±6.1%, respectively, and the prognosis of late relapse was significantly better than that of early relapse (P<0.001). The 3-year EFS rates of pediatric patients with bone marrow relapse in standard risk group, intermediate risk group and high risk group were 29.1±6.9, 31.3±6.5 and 28.3±6.3%, respectively; there were no statistically significant differences (P=0.387, P>0.05). Pediatric patients with B-ALL relapse are characterized by higher onset age (≥10 years old), high leukocyte count and hormone insensitivity. Dynamic monitoring of MRD level in B-ALL pediatric patients can predict the relapse.

Combination of cabazitaxel and plicamycin induces cell death in drug resistant B-cell acute lymphoblastic leukemia

Bone marrow microenvironment mediated downregulation of BCL6 is critical for maintaining cell quiescence and modulating therapeutic response in B-cell acute lymphoblastic leukemia (ALL). In the present study, we have performed a high throughput cell death assay using BCL6 knockdown REH ALL cell line to screen a library of FDA-approved oncology drugs. In the process, we have identified a microtubule inhibitor, cabazitaxel (CAB), and a RNA synthesis inhibitor, plicamycin (PLI) as potential anti-leukemic agents. CAB and PLI inhibited cell proliferation in not only the BCL6 knockdown REH cell line, but also six other ALL cell lines. Furthermore, combination of CAB and PLI had a synergistic effect in inhibiting proliferation in a cytarabine-resistant (REH/Ara-C) ALL cell line. Use of nanoparticles for delivery of CAB and PLI demonstrated that the combination was very effective when tested in a co-culture model that mimics the in vivo bone marrow microenvironment that typically supports ALL cell survival and migration into protective niches. Furthermore, exposure to PLI inhibited SOX2 transcription and exposure to CAB inhibited not only Mcl-1 expression but also chemotaxis in ALL cells. Taken together, our study demonstrates the utility of concomitantly targeting different critical regulatory pathways to induce cell death in drug resistant ALL cells.

Successful Treatment of a Very Late Isolated Relapse in an Adolescent With a PICALM-MLLT10 Positive T-lineage Acute Lymphoblastic Leukemia

T-lineage ALL is an aggressive disease that needs to be treated with intensive treatment schedules. A late relapse rarely occurs and a clear choice for second-line treatment is on debate. We report on a young adult with a very late isolated extramedullary relapse of PICALM-MLLT10 positive T-ALL, successfully treated with a chemotherapy-based and radiotherapy-based pediatric protocol. We demonstrate that relapse can occur in T-ALL although a SR-MRD behavior treated with a high-risk protocol; specific molecular diagnostic aberrations, as PICALM-MLLT10, are still conserved at very late relapse; a second-line treatment based on pediatric protocol can be effective.

Physical training interventions for children and teenagers affected by acute lymphoblastic leukemia and related treatment impairments

A decreased physical fitness has been reported in patients and survivors of acute lymphoblastic leukemia (ALL). This is influenced by the negative effects of the disease and by the treatments of childhood cancer.

In the past, children were advised to recover in bed, and to take as much relax as possible. Nowadays, it is considered that too much immobility may result in a further decrease of physical fitness and functioning. Exercise training for ALL children has frequently been reported to improve physical fitness and the well-being of the children, since it prevents the negative effects of a sedentary life-style, such as obesity and a poor skeletal health. In recent years, different studies and protocols on this subject has become available for children and young adults with cancer, both during and after treatment.

The efficacy of recent physical exercise training interventions, that act on several ALL impairments in children such as skeletal, musculoskeletal, neuromuscular, cardiopulmonary and cardiovascular systems, fatigue, body balance disorders and metabolism alterations have been examined.

These side effects might be prevented or significantly reduced by introducing a physical exercise program during or shortly after cancer treatment. Several interventions are discussed and presented for each impairment, reducing their level caused by the disease and thus suggesting the importance of physical training activity in ameliorating the children quality of life.

BCL6 modulation of acute lymphoblastic leukemia response to chemotherapy

The bone marrow niche has a significant impact on acute lymphoblastic leukemia (ALL) cell phenotype. Of clinical relevance is the frequency with which quiescent leukemic cells, in this niche, survive treatment and contribute to relapse. This study suggests that marrow microenvironment regulation of BCL6 in ALL is one factor that may be involved in the transition between proliferative and quiescent states of ALL cells. Utilizing ALL cell lines, and primary patient tumor cells we observed that tumor cell BCL6 protein abundance is decreased in the presence of primary human bone marrow stromal cells (BMSC) and osteoblasts (HOB). Chemical inhibition, or shRNA knockdown, of BCL6 in ALL cells resulted in diminished ALL proliferation. As many chemotherapy regimens require tumor cell proliferation for optimal efficacy, we investigated the consequences of constitutive BCL6 expression in leukemic cells during co-culture with BMSC or HOB. Forced chronic expression of BCL6 during co-culture with BMSC or HOB sensitized the tumor to chemotherapy induced cell death. Combination treatment of caffeine, which increases BCL6 expression in ALL cells, with chemotherapy extended the event free survival of mice. These data suggest that BCL6 is one factor, modulated by microenvironment derived cues that may contribute to regulation of ALL therapeutic response.

Salvaged allogeneic hematopoietic stem cell transplantation for pediatric chemotherapy refractory acute leukemia

There is an ongoing debate concerning the performance of salvaged allogeneic hematopoietic stem cell transplantation (allo-HSCT) in pediatric patients with acute refractory leukemia, in whom the prognosis is quite dismal. Few studies have ever been conducted on this subject. This may be partly due to missed opportunities by majority of the patients in such situations. To investigate the feasibility, evaluate the efficiency, and identify the prognostic factors of allo-HSCT in this sub-setting, the authors performed a single institution-based retrospective analysis. A total of 44 patients, of whom 28 had acute myeloid leukemia (AML), 13 had acute lymphocytic leukemia (ALL), and 3 had mixed phenotype leukemia (MPL), were enrolled in this study. With a median follow-up of 19 months, the estimated 2-year overall survival (OS) and progression free survival (PFS) were 34.3% (95% CI, 17.9–51.4%) and 33.6% (95% CI, 18.0–50.1%), respectively. The estimated 2-year incidence rates of relapse and non-relapse mortality (NRM) were 43.8% (95% CI 26.4–60.0%) and 19.6% (95% CI 9.1–32.9%), respectively. The estimated 100-day cumulative incidence of acute graft versus host disease (aGvHD) was 43.6% (95% CI 28.7–57.5%), and the 1-year cumulative incidence of chronic GvHD (cGvHD) was 45.5% (95% CI 30.5–59.3%). Compared with the previous studies, the multivariate analysis in this study additionally identified that female donors and cGvHD were associated with lower relapse and better PFS and OS. Male recipients, age younger than 10 years, a diagnosis of ALL, and the intermediate-adverse cytogenetic risk group were associated with increased relapse. On the contrary, extramedullary disease (EMD) and aGvHD were only linked to worse PFS. These data suggested that although only one-third of the patients would obtain PFS over 2 years, salvaged allo-HSCT is still the most reliable and best therapeutic strategy for refractory pediatric acute leukemia. If probable, choosing a female donor, better management of aGvHD, and induction of cGvHD promotes patient survival.

Gene Expression Profiling of Acute Lymphoblastic Leukemia in Children with Very Early Relapse

BACKGROUND AND AIMS

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer worldwide. Mexican patients have high mortality rates, low frequency of good prognosis biomarkers (i.e., ETV6-RUNX1) and a high proportion is classified at the time of diagnosis with a high risk to relapse according to clinical features. In addition, very early relapses are more frequently observed than in other populations. The aim of the study was to identify new potential biomarkers associated with very early relapse in Mexican ALL children through transcriptome analysis.

METHODS

Microarray gene expression profiling on bone marrow samples of 54 pediatric ALL patients, collected at time of diagnosis and/or at relapse, was performed. Eleven patients presented relapse within the first 18 months after diagnosis. Affymetrix Human Transcriptome Array 2.0 (HTA 2.0) was used to perform gene expression analysis. Annotation and functional enrichment analyses were carried out using Gene Ontology, KEGG pathway analysis and Ingenuity Pathway Analysis tools.

RESULTS

BLVRB, ZCCHC7, PAX5, EBF1, TMOD1 and BLNK were differentially expressed (fold-change >2.0 and p value <0.01) between relapsed and non-relapsed patients. Functional analysis of abnormally expressed genes revealed their important role in cellular processes related to the development of hematological diseases, cancer, cell death and survival and in cell-to-cell signaling interaction.

CONCLUSIONS

Our data support previous findings showing the relevance of PAX5, EBF1 and ZCCHC7 as potential biomarkers to identify a subgroup of ALL children in high risk to relapse.

ETS-related gene is a novel prognostic factor in childhood acute lymphoblastic leukemia

The ETS-related gene (ERG) has been demonstrated to be associated with overall survival in cytogenetically normal acute myeloid leukemia and acute T cell-lymphoblastic leukemia (T-ALL) in adult patients. However, there are no data available regarding the impact of ERG expression on childhood ALL. In the present study, ERG expression levels were analyzed in bone marrow samples from 119 ALL pediatric patients. ALL patients demonstrated higher ERG expression compared with the controls (P<0.0001). In addition, low ERG expression identified a group of patients with higher white blood cell counts (P=0.011), higher percentages of T-ALL immunophenotype (P=0.027), and higher relapse rates (P=0.009). Survival analyses demonstrated that low ERG expression was associated with inferior relapse-free survival (RFS) in childhood ALL (P=0.036) and was an independent prognostic factor in multivariable analyses for RFS. In conclusion, low ERG expression is associated with poor outcomes and may be used to serve as a molecular prognostic marker to identify patients with a high risk of relapse in childhood ALL.

Upregulation of the proto-oncogene Bmi-1 predicts a poor prognosis in pediatric acute lymphoblastic leukemia

BACKGROUND

Bmi-1, the B cell-specific moloney murine leukemia virus insertion site 1, is a member of the Polycomb-group (PcG) family and acts as an oncogene in various tumors; however, its expression related to the prognosis of pediatric patients with acute lymphoblastic leukemia (ALL) has not been well studied.

METHODS

The Bmi-1 expression levels in the bone marrow of 104 pediatric ALL patients and 18 normal control subjects were determined by using qRT-PCR. The association between the Bmi-1 expression and the clinicopathological characteristics of pediatric ALL patients was analyzed, and the correlation between Bmi-1 and the prognosis of pediatric ALL was calculated according to the Kaplan-Meier method. Furthermore, the association between Bmi-1 expression and its transcriptional regulator Sall4 was investigated.

RESULTS

Compared to normal control subjects, patients with primary pediatric ALL exhibited upregulated levels of Bmi-1. However, these levels were sharply decreased in patients who achieved complete remission. A significant positive association between elevated Bmi-1 levels and a poor response to prednisone as well as an increased clinical risk was observed. Patients who overexpressed Bmi-1 at the time of diagnosis had a lower relapse-free survival (RFS) rate (75.8%), whereas patients with lower Bmi-1 expression had an RFS of 94.1%. Furthermore, in ALL patients, the mRNA expression of Bmi-1 was positively correlated to the mRNA expression of Sall4a.

CONCLUSIONS

Taken together, these data suggest that Bmi-1 could serve as a novel prognostic biomarker in pediatric primary ALL and may be partially regulated by Sall4a. Our study also showed that Bmi-1 could serve as a new therapeutic target for the treatment of pediatric ALL.

Feasibility Study of a Novel Experimental Induction Protocol Combining B43-PAP (Anti-CD19) Immunotoxin With Standard Induction Chemotherapy in Children and Adolescents With Relapsed B-Lineage ALL: A Report From the Children's Oncology Group

BACKGROUND

B43-pokeweed antiviral protein (B43-PAP) is a high-affinity anti-CD19 immunotoxin that is capable of causing apoptotic death in B-lineage leukemic cells with a drug-resistant phenotype. B43-PAP exhibited in vivo antileukemic activity in preclinical studies as well as on a single-agent phase I clinical trial. This pediatric phase I/II study evaluated the toxicity profile and efficacy of B43-PAP immunotoxin in combination with standard induction chemotherapy in children and adolescents with relapsed CD19-positive B-lineage acute lymphoblastic leukemia (B-ALL). Pharmacokinetic profile and immunogenicity of B43-PAP were assessed.

EXPERIMENTAL DESIGN

B43-PAP in combination with standard 3 and 4-drug induction chemotherapy was administered on days 9-13 and 21-25 of a 28-day treatment course with vincristine, prednisone, L-asparaginase, daunomycin, and intrathecal methotrexate. Thirty patients with relapsed B-ALL were enrolled on study CCG-0957.

RESULTS

Grade III/IV nonhematologic dose-limiting toxicities were encountered in 4 patients evaluable for toxicity and included myalgias, motor dysfunction, pulmonary toxicity, and elevated liver transaminase. Dose-limiting toxicities occurred only with the 4-drug regimen. Fourteen patients achieved a complete remission at the end of induction among the 20 patients evaluable for response.

CONCLUSIONS

B43-PAP in combination with standard induction chemotherapy can be safely administered and exhibits clinical antileukemic activity against relapsed B-ALL.

In vitro and in vivo single-agent efficacy of checkpoint kinase inhibition in acute lymphoblastic leukemia

BACKGROUND

Although progress in children, in adults, ALL still carries a dismal outcome. Here, we explored the in vitro and in vivo activity of PF-00477736 (Pfizer), a potent, selective ATP-competitive small-molecule inhibitor of checkpoint kinase 1 (Chk1) and with lower efficacy of checkpoint kinase 2 (Chk2).

METHODS

The effectiveness of PF-00477736 as single agent in B-/T-ALL was evaluated in vitro and in vivo studies as a single agent. The efficacy of the compound in terms of cytotoxicity, induction of apoptosis, and changes in gene and protein expression was assessed using different B-/T-ALL cell lines. Finally, the action of PF-00477736 was assessed in vivo using leukemic mouse generated by a single administration of the tumorigenic agent N-ethyl-N-nitrosourea.

RESULTS

Chk1 and Chk2 are overexpressed concomitant with the presence of genetic damage as suggested by the nuclear labeling for γ-H2A.X (Ser139) in 68 % of ALL patients. In human B- and T-ALL cell lines, inhibition of Chk1/2 as a single treatment strategy efficiently triggered the Chk1-Cdc25-Cdc2 pathway resulting in a dose- and time-dependent cytotoxicity, induction of apoptosis, and increased DNA damage. Moreover, treatment with PF-00477736 showed efficacy ex vivo in primary leukemic blasts separated from 14 adult ALL patients and in vivo in mice transplanted with T-ALL, arguing in favor of its future clinical evaluation in leukemia.

CONCLUSIONS

In vitro, ex vivo, and in vivo results support the inhibition of Chk1 as a new therapeutic strategy in acute lymphoblastic leukemia, and they provide a strong rationale for its future clinical investigation.

CD19-antigen specific nanoscale liposomal formulation of a SYK P-site inhibitor causes apoptotic destruction of human B-precursor leukemia cells

We report the anti-leukemic potency of a unique biotargeted nanoscale liposomal nanoparticle (LNP) formulation of the spleen tyrosine kinase (SYK) P-site inhibitor C61. C61-loaded LNP were decorated with a murine CD19-specific monoclonal antibody directed against radiation-resistant CD19-receptor positive aggressive B-precursor acute lymphoblastic leukemia (ALL) cells. The biotargeted C61-LNP were more potent than untargeted C61-LNP and consistently caused apoptosis in B-precursor ALL cells. The CD19-directed C61-LNP also destroyed B-precursor ALL xenograft cells and their leukemia-initiating in vivo clonogenic fraction. This unique nanostructural therapeutic modality targeting the SYK-dependent anti-apoptotic blast cell survival machinery shows promise for overcoming the clinical radiochemotherapy resistance of B-precursor ALL cells.

Hematopoietic stem cell transplantation following unsuccessful salvage treatment for relapsed acute lymphoblastic leukemia in children

BACKGROUND

For children who experience a re-induction failure or multiple recurrences following the first relapse of acute lymphoblastic leukemia (ALL), it is uncertain whether additional intensive chemotherapy aimed at hematopoietic stem cell transplantation (SCT) in complete remission (CR) or immediate SCT even in non-CR should be performed. This study aimed to investigate the impact of disease status at SCT on the outcomes of SCT for these children, whose prognosis is considered unquestionably poor even with SCT.

PROCEDURE

The medical records of 55 children with ALL who underwent SCT following the experience of re-induction failure (n = 25) or multiple relapses (n = 30) were retrospectively analyzed.

RESULTS

Twenty-one patients underwent SCT in CR (delayed CR2, CR3, and CR4) and 34 in non-CR (first or subsequent relapse). The probability of overall survival of patients with CR and with non-CR at SCT was 42.9% and 23.5% (P = 0.15), leukemia-free survival was 38.1% and 20.6% (P = 0.18), and the cumulative incidence of relapse at 2 years was 23.8% and 50%, respectively (P = 0.05). In multivariate analysis, non-CR at SCT was a significant risk factor for higher relapse incidence and male sex was a significant risk factor for lower survival.

CONCLUSIONS

Our results indicated that in case of tolerable patient condition, further re-induction chemotherapy might be reasonable so that SCT could be performed in CR, which might result in a low incidence of relapse after SCT. Novel approaches are required to induce CR for the treatment of children with relapsed/refractory ALL.

Survival of Mexican Children with Acute Lymphoblastic Leukaemia under Treatment with the Protocol from the Dana-Farber Cancer Institute 00-01

Our aim in this paper is to describe the results of treatment of acute lymphoblastic leukaemia (ALL) in Mexican children treated from 2006 to 2010 under the protocol from the Dana-Farber Cancer Institute (DFCI) 00-01. The children were younger than 16 years of age and had a diagnosis of ALL de novo. The patients were classified as standard risk if they were 1–9.9 years old and had a leucocyte count <50 × 10⁹/L, precursor B cell immunophenotype, no mediastinal mass, CSF free of blasts, and a good response to prednisone. The rest of the patients were defined as high risk. Of a total of 302 children, 51.7% were at high risk. The global survival rate was 63.9%, and the event-free survival rate was 52.3% after an average follow-up of 3.9 years. The percentages of patients who died were 7% on induction and 14.2% in complete remission; death was associated mainly with infection (21.5%). The relapse rate was 26.2%. The main factor associated with the occurrence of an event was a leucocyte count >100 × 10⁹/L. The poor outcomes were associated with toxic death during induction, complete remission, and relapse. These factors remain the main obstacles to the success of this treatment in our population.

Outcome of pediatric acute lymphoblastic leukemia with very late relapse: a retrospective analysis by the Tokyo Children's Cancer Study Group (TCCSG)

Relapse period is strongly associated with second relapse risk in relapsed acute lymphoblastic leukemia (ALL) in children. In this context, the treatment outcome of very late relapse should be better; however, data regarding very late relapse is limited. We retrospectively analyzed the outcomes of two consecutive Tokyo Children's Cancer Study Group (TCCSG) ALL trials (1995-2004) with a focus on late relapse, which was divided into two categories: late relapse (6-24 months from the end of therapy, n = 48) and very late relapse (>24 months from the end of therapy, n = 57). Forty-three patients (29 late relapse and 14 very late relapse) received allogeneic hematopoietic stem cell transplantation (HSCT) at second remission. The event-free survival (EFS) probabilities of late relapse and very late relapse were 54.5 ± 7.3 and 64.8 ± 6.8 % at 7 years, respectively (P = 0.36), and were not significantly different. However, the second relapse incidence of late relapse (34.7 ± 7.1 %) was higher than that of very late relapse (15.5 ± 5.1 %, P = 0.03). The second relapse risk was low for very late relapse ALL, which suggests that these patients should be treated without allogeneic HSCT.

Current approach to relapsed acute lymphoblastic leukemia in children

Recurrent acute lymphoblastic leukaemia (ALL) is a common disease for pediatric oncologists and accounts for more deaths from cancer in children than any other malignancy. Although most patients achieve a second remission, about 50% of relapsed ALL patients do not respond to salvage therapy or suffer a second relapse and most children with relapse die. Treatment must be tailored after relapse of ALL, since outcome will be influenced by well-established prognostic features, including the timing and site of disease recurrence, the disease immunophenotype, and early response to retrieval therapy in terms of minimal residual disease (MRD). After reinduction chemotherapy, high risk (HR) patients are clear candidates for allogeneic stem cell transplantation (SCT) while standard risk patients do better with conventional chemotherapy and local therapy. Early MRD response assessment is currently applied to identify those patients within the more heterogeneous intermediate risk group who should undergo SCT as consolidation therapy. Recent evidence suggests distinct biological mechanisms for early vs late relapse and the recognition of the involvement of certain treatment resistance related genes as well cell cycle regulation and B-cell development genes at relapse, provides the opportunity to search for novel target therapies.

A pre-clinical model of resistance to induction therapy in pediatric acute lymphoblastic leukemia

Relapse and acquired drug resistance in T-cell acute lymphoblastic leukemia (T-ALL) remains a significant clinical problem. This study was designed to establish a preclinical model of resistance to induction therapy in childhood T-ALL to examine the emergence of drug resistance and identify novel therapies. Patient-derived T-ALL xenografts in immune-deficient (non-obese diabetic/severe combined immunodeficient) mice were exposed to a four-drug combination of vincristine, dexamethasone (DEX), L-asparaginase and daunorubicin (VXLD). ‘Relapse' xenografts were characterized by responses to drugs, changes in gene expression profiles and Connectivity Map (CMap) prediction of strategies to reverse drug resistance. Two of four xenografts developed ex vivo and in vivo drug resistance. Both resistant lines showed altered lipid and cholesterol metabolism, yet they had a distinct drug resistance pattern. CMap analyses reinforced these features, identifying the cholesterol pathway inhibitor simvastatin (SVT) as a potential therapy to overcome resistance. Combined ex vivo with DEX, SVT was significantly synergistic, yet when administered in vivo with VXLD it did not delay leukemia progression. Synergy of SVT with established chemotherapy may depend on higher drug doses than are tolerable in this model. Taken together, we have developed a clinically relevant in vivo model of T-ALL suitable to examine the emergence of drug resistance and to identify novel therapies.

Management of relapsed acute lymphoblastic leukemia in childhood with conventional and innovative approaches

PURPOSE OF REVIEW

To review and summarize the available evidence on factors predicting prognosis of children with relapsed acute lymphoblastic leukemia (ALL) and on the currently used treatment strategies, as well as on the most promising and innovative molecular or cellular therapies.

RECENT FINDINGS

Relapse still represents the most common cause of treatment failure, occurring in approximately 15-20% of childhood ALL. Risk-oriented standard salvage regimens are mostly based on combinations of the same agents incorporated in frontline therapies. Allogeneic hematopoietic stem cell transplantation (HSCT) is largely employed as postremission therapy, being superior to chemotherapy in high-risk patients. With conventional therapies including HSCT, 40-50% of children with relapsed ALL can be rescued. Thus, innovative approaches are needed to further improve the outcome of patients, especially when carrying poor prognostic factors. The last decade has witnessed the development of novel agents, including nucleoside analogues, anti-CD22 monoclonal antibodies and bi-specific, anti-CD3/CD19 antibodies, together with new formulations of existing chemotherapeutic agents and targeted molecules, such as tyrosine kinase inhibitors and FLT3 inhibitors.

SUMMARY

A significant proportion of children with relapsed ALL are salvaged by risk-oriented therapies. Novel agents should be integrated into combination regimens with the aim of further improving outcome of patients.

Precursor T-Cell Lymphoblastic Lymphoma Presenting as Cardiac Tamponade in a 25-Year-Old Male: A Case Report and Review of Literature

Precursor T-cell lymphoblastic lymphoma (LBL) and T-cell acute lymphoblastic leukemia (ALL) are considered same disease with different clinical presentations. Clinically, a case is defined as lymphoma if there is a mass lesion in the mediastinum or elsewhere and < 25% blasts in the bone marrow. Whereas, bone marrow with > 25% blasts with or without mediastinal masses is classified as T-cell ALL. Mediastinal masses caused by T-cell LBL can lead to complications such as superior vena cava syndrome, tracheal obstruction, pericardial effusion and tamponade. We report an unusual case of a 25-year-old male with no significant past medical history, who presented with clinical features of cardiac tamponade. Work-up revealed a massive pericardial effusion and a mass arising in the anterosuperior mediastinum. Patient underwent an emergent subxiphoid pericardial window and approximately 1 L of hemopericardium was drained. Histopathology (pericardial tissue) and flow cytometry on the pericardial fluid were compatible with a precursor T-cell LBL. Although pericardial involvement by lymphoma/leukemia is a very rare complication, cases have been reported with both lymphoma and acute/chronic leukemia. Our paper highlights cardiac tamponade as one of the life-threatening complications associated with a precursor T-cell LBL.

Validation of DNA methylation biomarkers for diagnosis of acute lymphoblastic leukemia

BACKGROUND

DNA methylation biomarkers capable of diagnosis and subtyping have been found for many cancers. Fifteen such markers have previously been identified for pediatric acute lymphoblastic leukemia (ALL). Validation of these markers is necessary to assess their clinical utility for molecular diagnostics. Substantial efficiencies could be achieved with these DNA methylation markers for disease tracking with potential to replace patient-specific genetic testing.

METHODS

We evaluated DNA methylation of promoter regions of TLX3 (T-cell leukemia homeobox) and FOXE3 (forkhead box E3) in bone marrow biopsies from 197 patients classified as leukemic (n = 95) or clear of the disease (n = 102) by MALDI-TOF. Using a single nucleotide extension assay (methylSABER), we tested 10 bone marrow biopsies collected throughout the course of patient chemotherapy. Using reference materials, diagnostic thresholds and limits of detection were characterized for both methods.

RESULTS

Reliable detection of DNA methylation of TLX3 and FOXE3 segregated ALL from those clear of disease with minimal false-negative and false-positive results. The limit of detection with MALDI-TOF was 1000-5000 copies of methylated allele. For methylSABER, the limit of detection was 10 copies of methylated TLX3, which enabled monitoring of minimal residual disease in ALL patients.

CONCLUSIONS

Mass spectrometry procedures can be used to regionally multiplex and detect rare DNA methylation events, establish DNA methylation loci as clinically applicable biomarkers for disease diagnosis, and track pediatric ALL.

Children Diagnosed as Mixed-Phenotype Acute Leukemia Didn't Benefit from the CCLG-2008 Protocol, Retrospective Analysis from Single Center

Mixed phenotype acute leukemia (MPAL) is a rare type of acute leukemia with a poor clinical outcome which lacks specific therapy. To evaluate the therapeutic efficiency of CCLG-2008 protocol used for acute lymphoblastic leukemia (ALL) in China on MPAL children who were initially diagnosed as ALL by morphology, we reviewed patients' database diagnosed as ALL and MPAL according to WHO classification and compared their outcomes from July 2008 to June 2012. Total newly enrolled ALL in this study were 309 cases by morphology, in which ten cases were identified as MPAL mainly by immunophenotyping: B+ myeloid (3/10), T+ myeloid (2/10), B + T (4/10), trilineage (1/10). Two cases were classified as intermediate risk (IR) and 8 cases were high risk (HR) according to the CCLG-2008 criteria. Only one case of IR survived and others died due to primary resistance of chemotherapy and relapse. Compared with MPAL, ALL children in IR and HR had a longer survival (28.1 vs 9.5 months, p < 0.0001) and lower relapse (16.3 vs 85.7 %, p = 0.0002). In a summary, our result indicated that MPAL in children is a poor-risk disease which needs personalized therapy to improve outcome.

Effect of microRNA-210 on prognosis and response to chemotherapeutic drugs in pediatric acute lymphoblastic leukemia

Many studies have demonstrated that microRNA-210 (miR-210) expression is intensively upregulated in hypoxic states and differentially regulated in most types of cancer cells. However, the clinical significance of miR-210 and its effects on the response of leukemic cells to chemotherapeutic drugs in childhood acute lymphoblastic leukemia (ALL) remain unknown. In the current study, using real-time qRT-PCR to detect miR-210 expression in bone marrow samples from 114 children at initial diagnosis of ALL, we investigated the prognostic significance of miR-210 and determined its associations with common clinical characteristics and treatment outcome. We further examined its effect on the response to chemotherapeutic drugs in the Reh and RS4;11 cell lines. Results showed that miR-210 expression was significantly lower in patients suffering from relapse and induction failure than in other patients (P < 0.001). Using the receiver operating characteristic curve, 3.8243 was selected as the cut-off value of miR-210 expression in our test cohort (38 cases). A significantly poorer treatment outcome (P < 0.05) was found in the low-expression group and verified in the validation cohort (76 cases, P < 0.05). Patients with low expression of miR-210 and positive minimal residual disease at the end of induction had a much higher rate of relapse or induction failure (P = 0.001). Increasing/decreasing miR-210 expression using agomir/antagomir could enhance or reduce the response of Reh cells and RS4;11 cells to daunorubicin/dexamethasone/L-asparaginase and daunorubicin/dexamethasone/vincristine, respectively. In conclusion, miR-210 may be a good prognostic factor and a useful predictor of drug sensitivity, and is a potential therapeutic target for pediatric ALL.

Epigenetics and chemoresistance in childhood acute lymphoblastic leukemia

SUMMARY For children with acute lymphoblastic leukemia (ALL) who relapse, prognosis is poor and novel therapeutic strategies are needed. In the last decade, it has become apparent that ALL exhibits unique epigenetic patterns in addition to the well known cytogenetic findings. Furthermore, whole genome sequencing efforts are revealing recurrent mutations in epigenetic modifiers in ALL. Aberrant epigenetic modulation may be involved in leukemic transformation and resistance to chemotherapy. Consequently, compounds that specifically modulate the maintenance of such epigenetic programs may offer new approaches to therapy, including the modulation or prevention of chemoresistance in ALL. In this article, we review some of the most recent findings with regard to epigenetic aberrations in ALL, and discuss therapeutic strategies that are currently in development.

Outcome of children and adolescents with a second or third relapse of acute lymphoblastic leukemia (ALL): a population-based analysis of the Austrian ALL-BFM (Berlin-Frankfurt-Münster) study group

We analyzed outcome of a population-based cohort of 74 children with second and third acute lymphoblastic leukemia (ALL) relapse and aimed to identify prognostic factors. Duration of previous remission and site of relapse appeared of prognostic relevance as patients with a second remission duration >1.5 years and isolated extramedullary relapse did better. Neither patient with a second bone marrow relapse who underwent previous allogeneic transplantation nor patients with T-cell ALL survived. Overall, 7 of 74 (9%) patients are in long-term remission. Stem cell transplantation seemed to be the only curative option for systemic relapse of B-cell precursor ALL as all 4 surviving patients with a second/third relapse involving the bone marrow received a transplant. Conclusively, patients with a second ALL relapse are ideal candidates for phase I/II trials exploring new innovative drugs.

Relapsed childhood acute lymphoblastic leukaemia

With steadily improved cure rates for children with newly diagnosed acute lymphoblastic leukaemia (ALL), treating relapsed ALL has become increasingly challenging largely due to resistance to salvage therapy. Improved biological understanding of mechanisms of relapse and drug resistance, the identification of actionable molecular targets by studying leukaemic cell and host genetics, precise risk stratification with minimum residual disease measurement, and the development of new therapeutic drugs and approaches are needed to improve outcomes of relapsed patients. Molecularly targeted therapies and innovative immunotherapeutic approaches that include specialised monoclonal antibodies and cellular therapies hold promise of enhanced leukaemia cell killing with non-overlapping toxicities. Advances in preparative regimens, donor selection, and supportive care should improve the success of haemopoietic stem-cell transplantation for high-risk patients.

Parthenolide eliminates leukemia-initiating cell populations and improves survival in xenografts of childhood acute lymphoblastic leukemia

Approximately 20% of children with acute lymphoblastic leukemia (ALL) relapse because of failure to eradicate the disease. Current drug efficacy studies focus on reducing leukemia cell burden. However, if drugs have limited effects on leukemia-initiating cells (LICs), then these cells may expand and eventually cause relapse. Parthenolide (PTL) has been shown to cause apoptosis of LIC in acute myeloid leukemia. In the present study, we assessed the effects of PTL on LIC populations in childhood ALL. Apoptosis assays demonstrated that PTL was effective against bulk B- and T-ALL cells, whereas the CD34(+)/CD19(-), CD34(+)/CD7(-), and CD34(-) subpopulations were more resistant. However, functional analyses revealed that PTL treatment prevented engraftment of multiple LIC populations in NOD/LtSz-scid IL-2Rγ(c)-null mice. PTL treatment of mice with established leukemias from low- and high-risk patients resulted in survival and restoration of normal murine hemopoiesis. In only 3 cases, disease progression was significantly slowed in mice engrafted with CD34(+)/CD19(-) or CD34(+)/CD7(-) and CD34(-) cells, but was not prevented, demonstrating that individual LIC populations within patients have different responses to therapy. These observations indicate that PTL may have therapeutic potential in childhood ALL and provide a basis for developing effective therapies that eradicate all LIC populations to prevent disease progression and reduce relapse.

Minimal residual disease after induction is the strongest predictor of prognosis in intermediate risk relapsed acute lymphoblastic leukaemia - long-term results of trial ALL-REZ BFM P95/96

PURPOSE

This blinded prospective study was performed to optimise the risk assessment of children with a late isolated, combined or an early combined bone marrow (BM) relapse of precursor B-cell acute lymphoblastic leukaemia (ALL). The aim was to develop a reliable tool to identify patients with an intermediate risk relapse who are in need of haematopoietic stem cell transplantation (HSCT).

METHODS

Included were 80 children and adolescents with first intermediate risk BM relapse of ALL recruited in trial ALL-REZ BFM P95/96. We assessed the prognostic value of minimal residual disease (MRD) after induction therapy quantified by PCR using leukaemia clone-specific T-cell receptor/immunoglobulin gene rearrangements.

RESULTS

Molecular good responders (MRD < 10(-3), n=46) had a probability of event-free survival (pEFS) at 10 years of 76% standard error (SE) ± 6% and a cumulative incidence of second relapse (CIR) at 10 years of 21% SE ± 6%; pEFS of molecular poor responders (MRD ≥ 10(-3), n=34) at 10 years was 18% SE ± 7% and CIR 61% SE ± 9% (p<0.001). Cox regression analysis revealed MRD after induction to be the strongest independent prognostic parameter with a 6.6-fold increased risk (95% confidence interval 3.3-13.5, p<0.001) for molecular poor responders to suffer a subsequent adverse event compared to good responders.

CONCLUSION

In patients with intermediate risk BM relapse of ALL, low MRD after induction is associated with an excellent long-term prognosis with conventional chemo-/radiotherapy whereas patients with insufficient response have an extremely poor prognosis. Therefore, in the subsequent trial ALL-REZ BFM 2002, MRD is used to allocate molecular good responders to conventional post-induction therapy and molecular poor responders to allogeneic HSCT.