Childhood relapsed acute lymphoblastic leukemia: Biology and recent treatment progress

Treatment of relapsed acute lymphoblastic leukemia in children: an observational study of the Japan Children's Cancer Group

The Japan Children's Cancer Group Relapsed Acute Lymphoblastic Leukemia (ALL) Committee conducted a prospective observational study (ALL-R14) to explore promising reinduction therapy regimens for relapsed ALL to investigate in future trials. In Japan, clofarabine- and bortezomib-based regimens were of interest since they were newly introduced for ALL in the study period (2015-2018). Seventy-five pediatric patients were enrolled in total. The 2-year event-free/overall survival rates in patients with first (n = 59) or second (n = 11) relapse were 40.1% (95% confidence interval [CI]: 25.5-52.3%)/66.3% (95% CI 52.3-77.0%) and 34.1% (95% CI 9.1-61.6%)/62.3% (95% CI 27.7-84.0%), respectively. Clofarabine- or bortezomib-based regimens were used only in patients with high-risk disease. The first reinduction therapy used in the 41 patients with early or multiple relapsed B-cell precursor ALL was clofarabine in 7 patients and bortezomib in 9 patients. The odds ratio for reinduction failure risk with a clofarabine- or bortezomib-based regimen compared with other regimens was 9.0 (95% CI 0.9-86.4, P = 0.057) or 1.9 (95% CI 0.4-8.7, P = 0.42), respectively. Thus, clofarabine- or bortezomib-based regimens had no obvious advantage as reinduction therapy for relapsed ALL in children.

Survival and prognostic factors for relapsed childhood acute lymphoblastic leukemia after treatment with the Chinese children's cancer group ALL-2015 protocol: a single center results

Introduction

This retrospective study was conducted to assess the survival rates and prognostic factors in children with relapsed acute lymphoblastic leukemia (ALL) who were treated according to the Chinese Children's Cancer Group ALL-2015 protocol at the Children's Hospital of Chongqing Medical University.

Methods

The study cohort involving 852 evaluable children with ALL reported a total of 146 relapses during a median follow-up period of 53 months. The primary outcomes measured were the second complete remission (CR2) rates, and 5-year event-free survival (EFS) and overall survival (OS) for patients who received re-treatment post-relapse. Patient data were stratified by ALL subtype (B-ALL vs. T-ALL), age at relapse, site of relapse, and timing of relapse. Univariate and multivariate analyses were performed to identify factors significantly associated with EFS and OS.

Results

As of March 31, 2023, 146 relapses were observed, including 128 B-ALL and 18 T-ALL cases. The 8-year CIR was (19.8 ± 1.6)%, with no significant difference between B-ALL and T-ALL (P=0.271). Among the 105 patients who underwent re-treatment, 70 achieved CR2, resulting in a CR2 rate of 67.6%. The 5-year EFS and OS rates for re-treated patients were (45.0 ± 5.4)% and (56.9 ± 5.2)%, respectively. Significant differences in 5-year OS and EFS were found between B-ALL and T-ALL relapses (P < 0.001). The 5-year EFS and OS varied significantly with relapse timing and site of relapse. Factors significantly affecting EFS after relapse included the site of relapse, immunophenotyping, CR2 achievement, and hematopoietic stem cell transplantation (HSCT). Immunophenotyping, CR2 achievement, and HSCT were also identified as significant factors affecting OS after relapse.

Discussion

Despite treatment with the CCCG-ALL-2015 protocol, a significant relapse rate was observed, with 72% of children opting for re-treatment post-relapse. The study highlights the importance of considering specific prognostic factors to inform tailored treatment strategies for relapsed childhood ALL. The findings emphasize the need for further research into improving therapeutic approaches for this patient population. This retrospective study was conducted to assess the survival rates and prognostic factors in children with relapsed acute lymphoblastic leukemia (ALL) who were treated according to the Chinese Children's Cancer Group ALL-2015 protocol at the Children's Hospital of Chongqing Medical University.

Cellular pharmacokinetic of methotrexate and its modulation by folylpolyglutamate synthetase and γ-glutamyl hydrolase in tumor cells

BACKGROUND AND PURPOSE

Clinical studies showed that prolonged infusion of methotrexate (MTX) leads to more severe adverse reactions than short infusion of MTX at the same dose. We hypothesized that it is the saturation of folate polyglutamate synthetase (FPGS) at high MTX concentration that limits the intracellular synthesis rate of methotrexate polyglutamate (MTX-PG). Due to a similar accumulation rate, a longer infusion duration may increase the concentration of MTX-PG and, result in more serious adverse reactions. In this study, we validated this hypothesis.

EXPERIMENTAL APPROACH

A549, BEL-7402 and MHCC97H cell lines were treated with MTX at gradient concentrations. Liquid chromatograph-mass spectrometer (UPLC-MS/MS) was used to quantify the intracellular concentration of MTX-PG and the abundance of FPGS and γ-glutamyl hydrolase (GGH). High quality data were used to fit the cell pharmacokinetic model.

KEY RESULTS

Both cell growth inhibition rate and intracellular MTX-PG concentration showed a nonlinear relationship with MTX concentration. The parameter Vmax in the model, which represents the synthesis rate of MTX-PG, showed a strong correlation with the abundance of intracellular FPGS.

CONCLUSION AND IMPLICATIONS

According to the model fitting results, it was confirmed that the abundance of FPGS is a decisive factor limiting the synthesis rate of MTX-PG. The proposed hypothesis was verified in this study. In addition, based on the intracellular metabolism, a reasonable explanation was provided for the correlation between the severity of adverse reactions of MTX and infusion time. This study provides a new strategy for the individualized treatment and prediction of efficacy/side effects of MTX.

MG132 inhibits proliferation and induces apoptosis of acute lymphoblastic leukemia via Akt/FOXO3a/Bim pathway

BACKGROUND

Acute lymphoblastic leukemia (ALL) is one of the most common pediatric cancers, characterized by the malignant proliferation of leukemic cells. Despite advancements in treatment, the prognosis for refractory and relapsed ALL remains poor, underscoring the need for novel therapeutic targets and approaches.

METHODS

To investigate the anti-leukemic properties of MG132, MTS assays were employed to assess cell viability, and flow cytometry was used to evaluate apoptosis. Mechanistic studies, including qRT-PCR, Western blotting, and lentivirus-mediated FOXO3a knockdown, were conducted to explore MG132's effects on the Akt/FOXO3a/Bim signaling pathway. A xenograft mouse model was utilized to validate the in vivo efficacy of MG132 in suppressing tumor growth.

RESULTS

MG132 inhibited cell proliferation and induced apoptosis in both ALL cell lines and primary cells in a concentration-dependent manner. Mechanistic studies revealed that MG132 promoted FOXO3a nuclear localization by suppressing Akt phosphorylation and preventing FOXO3a degradation, leading to increased Bim expression. Furthermore, FOXO3a knockdown significantly reduced MG132's anti-proliferative effects. In vivo, MG132 markedly inhibited tumor growth in the xenograft model.

CONCLUSION

These findings suggest that MG132 exerts potent anti-leukemic effects through modulation of the Akt/FOXO3a/Bim axis, offering a promising therapeutic avenue for treating ALL.

Acute lymphoblastic leukemia relapse presenting with optic nerve infiltration

Acute lymphoblastic leukemia is the most common childhood malignancy. Despite many advances in therapy, about 15%-20% of children with acute lymphoblastic leukemia experience a disease relapse. Isolated ocular relapse is relatively rare. A 14-year-old male with T-cell acute lymphoblastic leukemia in remission presented with sudden onset of right eye pain and visual acuity impairment. Fundoscopic examination of the eye and magnetic resonance imaging of the orbits were consistent with optic nerve infiltration. The patient was treated with salvage chemotherapy, orbital radiation and eventual bone marrow transplantation, with notable improvement in vision and regression of retinal and optic nerve findings. Optic nerve infiltration represents an ophthalmic emergency and requires urgent management. The use of radiation therapy is a helpful adjunct with systemic chemotherapy in obtaining disease remission.

Targeting Glutaminolysis Shows Efficacy in Both Prednisolone-Sensitive and in Metabolically Rewired Prednisolone-Resistant B-Cell Childhood Acute Lymphoblastic Leukaemia Cells

The prognosis for patients with relapsed childhood acute lymphoblastic leukaemia (cALL) remains poor. The main reason for treatment failure is drug resistance, most commonly to glucocorticoids (GCs). The molecular differences between prednisolone-sensitive and -resistant lymphoblasts are not well-studied, thereby precluding the development of novel and targeted therapies. Therefore, the aim of this work was to elucidate at least some aspects of the molecular differences between matched pairs of GC-sensitive and -resistant cell lines. To address this, we carried out an integrated transcriptomic and metabolomic analysis, which revealed that lack of response to prednisolone may be underpinned by alterations in oxidative phosphorylation, glycolysis, amino acid, pyruvate and nucleotide biosynthesis, as well as activation of mTORC1 and MYC signalling, which are also known to control cell metabolism. In an attempt to explore the potential therapeutic effect of inhibiting one of the hits from our analysis, we targeted the glutamine-glutamate-α-ketoglutarate axis by three different strategies, all of which impaired mitochondrial respiration and ATP production and induced apoptosis. Thereby, we report that prednisolone resistance may be accompanied by considerable rewiring of transcriptional and biosynthesis programs. Among other druggable targets that were identified in this study, inhibition of glutamine metabolism presents a potential therapeutic approach in GC-sensitive, but more importantly, in GC-resistant cALL cells. Lastly, these findings may be clinically relevant in the context of relapse-in publicly available datasets, we found gene expression patterns suggesting that in vivo drug resistance is characterised by similar metabolic dysregulation to what we found in our in vitro model.

A Review of CAR-T Therapy in Pediatric and Young Adult B-Lineage Acute Leukemia: Clinical Perspectives in Singapore

Approximately 10-15% of pediatric B-cell acute lymphoblastic leukemia (B-ALL) are high risk at diagnosis or relapsed/ refractory. Prior to the availability of chimeric antigen receptor T-cell (CAR-T) in Singapore and the region, the treatment options for these paediatric and young adults are conventional salvage chemotherapy or chemo-immunotherapy regimens as a bridge to allogeneic total body irradiation-based hematopoietic stem cell transplantation (allo-HSCT). This results in significant acute and long-term toxicities, with suboptimal survival outcomes. Finding a curative salvage therapy with fewer long-term toxicities would translate to improved quality-adjusted life years in these children and young adults. In this review, we focus on the burden of relapsed/refractory pediatric B-ALL, the limitations of current strategies, the emerging paradigms for the role of CAR-T in r/r B-ALL, our local perspectives on the health economics and future direction of CAR-T therapies in pediatric patients.

Relapsed acute lymphoblastic leukaemia after allogeneic stem cell transplantation: a therapeutic dilemma challenging the armamentarium of immunotherapies currently available (case reports)

While survival rates in paediatric acute lymphoblastic leukaemia (ALL) nowadays exceed 90%, systemic ALL relapse, especially after haemopoietic stem cell transplantation (HSCT), is associated with a poor outcome. As there is currently no standardized treatment for this situation, individualized treatment is often pursued. Exemplified by two clinical scenarios, the aim of this article is to highlight the challenge for treating physicians to find a customized treatment strategy integrating the role of conventional chemotherapy, immunotherapeutic approaches and second allogeneic HSCT. Case 1 describes a 2-year-old girl with an early isolated bone marrow relapse of an infant KMT2A-rearranged B-cell precursor ALL after allogeneic HSCT. After bridging chemotherapy and lymphodepleting chemotherapy, chimeric antigen receptor (CAR) T-cells (tisagenlecleucel) were administered for remission induction, followed by a second HSCT from the 9/10 human leukocyte antigen (HLA)-matched mother. Case 2 describes a 16-year-old girl with a late, isolated bone marrow relapse of B-cell precursor ALL after allogeneic HSCT who experienced severe treatment toxicities including stage IV renal insufficiency. After dose-reduced bridging chemotherapy, CAR T-cells (tisagenlecleucel) were administered for remission induction despite a CD19^- clone without prior lymphodepletion due to enhanced persisting toxicity. This was followed by a second allogeneic HSCT from the haploidentical mother. While patient 2 relapsed around Day + 180 after the second HSCT, patient 1 is still in complete remission >360 days after the second HSCT. Both cases demonstrate the challenges associated with systemic ALL relapse after first allogeneic HSCT, including chemotherapy-resistant disease and persisting organ damage inflicted by previous therapy. Immunotherapeutic approaches, such as CAR T-cells, can induce remission and enable a second allogeneic HSCT. However, optimal therapy for systemic ALL relapse after first HSCT remains to be defined.

Population Pharmacokinetics of Blinatumomab in Pediatric and Adult Patients with Hematological Malignancies

BACKGROUND AND OBJECTIVES

Blinatumomab (BLINCYTO^®) is a novel bispecific T cell engager (BiTE^®) approved in the USA for the treatment of relapsed or refractory B cell precursor acute lymphoblastic leukemia (ALL) in children and adults, as well as minimal residual disease ALL in adults. This analysis characterized the population pharmacokinetics of intravenous blinatumomab in pediatric and adult patients.

METHODS

A total of 2417 serum concentrations of blinatumomab from 674 patients, including adult (n = 628) and pediatric patients (n = 46), from eight clinical studies were analyzed. The impact of covariates on pharmacokinetic parameters were explored, and significant covariates were further evaluated using a simulation approach.

RESULTS

Blinatumomab pharmacokinetics were described by a one-compartment linear model with first-order elimination, a clearance (CL) of 2.22 L/h, and a central volume of 5.98 L. A statistically significant effect of body surface area (BSA) on CL was observed. The smallest BSA of 0.37 m² in the pediatric population was associated with a 63% reduction in blinatumomab systemic CL, relative to an adult patient with the median BSA (1.88 m²), supporting the use of BSA-based dosing in patients of lower bodyweight. The BSA effect was minimal, with a ≤ 25% change in CL over the range of BSA in adults, supporting no need for BSA-based dosing.

CONCLUSIONS

Blinatumomab pharmacokinetics were adequately described by a one-compartment linear model with first-order elimination. No covariates other than BSA on CL were identified as significant. BSA-based dosing should be considered for lightweight patients to minimize inter-subject variability in blinatumomab exposure.

The Protozoan Inhibitor Atovaquone Affects Mitochondrial Respiration and Shows In Vitro Efficacy Against Glucocorticoid-Resistant Cells in Childhood B-Cell Acute Lymphoblastic Leukaemia

Childhood acute lymphoblastic leukaemia (cALL) accounts for about one third of all paediatric malignancies making it the most common cancer in children. Alterations in tumour cell metabolism were first described nearly a century ago and have been acknowledged as one of the key characteristics of cancers including cALL. Two of the backbone chemotherapeutic agents in the treatment of this disease, Glucocorticoids and L-asparaginase, are exerting their anti-leukaemic effects through targeting cell metabolism. Even though risk stratification and treatment regimens have improved cure rates to nearly 90%, prognosis for relapsed children remains poor. Therefore, new therapeutic approaches are urgently required. Atovaquone is a well-tolerated drug used in the clinic mainly against malaria. Being a ubiquinone analogue, this drug inhibits co-enzyme Q10 of the electron transport chain (ETC) affecting oxidative phosphorylation and cell metabolism. In this study we tested the effect of Atovaquone on cALL cells in vitro. Pharmacologically relevant concentrations of the inhibitor could effectively target mitochondrial respiration in both cALL cell lines (REH and Sup-B15) and primary patient samples. We found that Atovaquone leads to a marked decrease in basal respiration and ATP levels, as well as reduced proliferation, cell cycle arrest, and induction of apoptosis. Importantly, we observed an enhanced anti-leukaemic effect when Atovaquone was combined with the standard chemotherapeutic Idarubicin, or with Prednisolone in an in vitro model of Glucocorticoid resistance. Repurposing of this clinically approved inhibitor renders further investigations, but also presents opportunities for fast-track trials as a single agent or in combination with standard chemotherapeutics.

Outcomes in Pediatric Acute Lymphoblastic Leukemia-A Single-Center Romanian Experience

BACKGROUND

This study evaluates the main (para)clinical aspects and outcomes in a group of Romanian children diagnosed with acute lymphoblastic leukemia (ALL), under the conditions of antileukemic treatment according to an adapted ALL IC Berlin-Frankfurt-Munster (BFM) 2002 protocol.

METHODS

We performed a retrospective single-center study of 125 children diagnosed with ALL between 2010 and 2016. Standard forms were used for data collection of variate clinical and paraclinical parameters.

RESULTS

The children were predominantly male (64.8%) and their median age at diagnosis was 5 years. A total of 107 patients were diagnosed with precursor B-cell acute lymphoblastic leukemia (BCP)-ALL and 18 with T-cell acute lymphoblastic leukemia T-ALL. Multiplex reverse transcription polymerase chain reaction RT-PCR assay for ETV6-RUNX1, BCR-ABL, E2A-PBX1, KMT2A-AFF1, and STIL-TAL1 fusion genes was performed in 111 patients. ETV6-RUNX1 translocation was detected in 18.9% of patients, while BCR-ABL1 and E2A-PBX1 rearrangements were seen in 2.7% and 3.6%, respectively. Complete remission at the end of induction phase was obtained in 89.6% of patients. The overall relapse rate was 11.2%, with 11 early and 3 late relapses. The 5-year overall survival rate in BCP-ALL was 81.6% and in T-ALL 71.4%.

CONCLUSIONS

The 5-year overall and event-free survival rates in our study were slightly lower than those reported in developed countries, so the patients' outcomes are encouraging.

Bispecific antibodies in acute lymphoblastic leukemia therapy

INTRODUCTION

Blinatumomab, first in a class of bispecific T-cell engagers, revolutionized treatment paradigm of B-cell precursor relapsed/refractory or minimal residual disease positive acute lymphoblastic leukemia (ALL) in adults and children, inducing deep remissions in a proportion of patients. However, significant numbers of patients do not respond or eventually relapse. Strategies for improvement of treatment outcomes are required.

AREAS COVERED

This review discusses the main structural and functional features of blinatumomab, and its place in the treatment of ALL. Furthermore, prospects to increase the efficacy of blinatumomab are addressed. The developments in the field of bispecific antibodies and their possible implications for treatment of ALL are reviewed.

EXPERT OPINION

Better understanding the mechanisms of response and resistance to blinatumomab might help us to identify the group of patients benefiting most from treatment and to spare potentially toxic subsequent treatment strategies. Data emerging from ongoing clinical trials might change the treatment landscape of ALL and beyond. Early use of blinatumomab in frontline protocols with more advantageous treatment sequences and in combination with other targeted therapies might reduce the failure rates. Exponentially increasing number of novel treatment options and their possible combinations might complicate treatment decision-making without data from randomized trials.

Relapsed Childhood Acute Lymphoblastic Leukemia: A Single-Institution Experience

Background Even though the treatment outcomes of childhood acute lymphoblastic leukemia (ALL) have improved recently, relapse of the disease still remains a challenge in developing countries. This study aims to analyze the incidence of relapse and survival rates in childhood ALL. Methods A retrospective study of 156 children with de novo ALL between 2012-2018 was conducted. Data on age, gender, relapse type, and relapse time were analyzed. Results A total of 26 (16.7%) patients experienced relapse, with a male-to-female ratio of 2.71:1. The relapse rate in the high-risk group was 1.6 times greater than that in the standard-risk group (61.5% vs. 38.5%). The median time from diagnosis to relapse was 29.3 months (38.5% in the early stage, 26.9% in the intermediate, and 34.6% in the late stage). The most common relapse site was bone marrow (38.5%), followed by the isolated central nervous system (CNS, 23.1%) and CNS plus bone marrow (23.1%); the least common site was testicle with or without bone marrow or CNS (15.2%). The median post-relapse survival time was 7.5 months. Conclusion Modification of the protocol to use escalated methotrexate dose and providing new therapies such as stem cell transplantation can improve the overall survival rates in relapsed ALL patients.

Day 15 and Day 33 Minimal Residual Disease Assessment for Acute Lymphoblastic Leukemia Patients Treated According to the BFM ALL IC 2009 Protocol: Single-Center Experience of 133 Cases

Introduction: Childhood acute lymphoblastic leukemia (ALL) is a hematologic malignancy characterized by the acquisition of several genetic lesions in the lymphoid progenitors with subsequent proliferation advantage and lack of maturation. Along the years, it has been repeatedly shown that minimal residual disease (MRD) plays an important role in prognosis and therapy choice. The aim of the current study was to determine the prognostic role of MRD in childhood ALL patients in conjunction with other relevant patient and disease characteristics, thus showing the real-life scenario of childhood ALL. Patients and Methods: The retrospective study includes childhood ALL patients that were treated according to the BFM ALL IC 2009 between January 2016 and December 2018 at the Fundeni Clinical Institute, Bucharest, Romania. Results: None of the variables significantly influenced the induction-related death in our study. None of the variables independently predicted relapse-free survival (RFS) with the highest tendency for statistical significance being represented by poor prednisone response. Non-relapse mortality (NRM) was independently predicted by age, prednisone response, and day 33 flow cytometry-MRD (FCM-MRD). Overall survival (OS) was independently predicted by prednisone response and day 33 FCM-MRD. Event-free survival (EFS) was independently predicted by age, prednisone response, and day 33 FCM-MRD. Conclusion : Prednisone response, day 15 FCM-MRD, day 33 FCM-MRD, and the risk group represent the most important factors that in the current study independently predict childhood ALL prognosis.

POI after chemotherapy and bone marrow transplant may mimic disorders of sexual differentiation - a case report of a patient with primary amenorrhea and 46, XY karyotype

Cytogenetic examination may be useful in determining the reason for primary amenorrhea in phenotypically female patients. The result 46, XY usually indicates two syndromes: complete androgen insensitivity or pure gonadal dysgenesis. We report a case of a patient, who due to acute lymphoblastic leukemia in childhood was treated with total body irradiation and bone marrow transplantation. Later on the patient presented with symptoms typical for premature ovarian failure and male karyotype in peripheral lymphocytes. The cytogenetic examination for peripheral cells showed normal female karyotype. Therefore, it has been concluded that ovarian function impairment resulted rather from the gonadotoxic effect of oncological treatment than as a disorder of sexual differentiation. The survival rates of childhood cancer are very high and some of the patients will experience premature ovarian failure. It must be remembered that after bone marrow transplantation karyotype of peripheral lymphocytes may be misleading.

Metabolic reprogramming in childhood acute lymphoblastic leukemia

The first observations of altered metabolism in malignant cells were made nearly 100 years ago and therapeutic strategies targeting cell metabolism have been in clinical use for several decades.  In this review, we summarize our current understanding of cell metabolism dysregulation in childhood acute lymphoblastic leukemia (cALL). Reprogramming of cellular bioenergetic processes can be expected in the three distinct stages of cALL: at diagnosis, during standard chemotherapy, and in cases of relapse. Upregulation of glycolysis, dependency on anaplerotic energy sources, and activation of the electron transport chain have all been observed in cALL. While the current treatment strategies are tackling some of these aberrations, cALL cells are likely to be able to rewire their metabolism in order to escape therapy, which may contribute to a refractory disease and relapse. Finally, here we focus on novel therapeutic approaches emerging from our evolving understanding of the alterations of different metabolic networks in lymphoblasts.

Aurora B kinase as a therapeutic target in acute lymphoblastic leukemia

PURPOSE

Acute lymphoblastic leukemia (ALL) is curable with standardized chemotherapy. However, the development of novel therapies is still required, especially for patients with relapsed or refractory disease. By utilizing an in vitro drug screening system, active molecular targeting agents against ALL were explored in this study.

METHODS

By the in vitro drug sensitivity test, 81 agents with various actions were screened for their cytotoxicity in a panel of 22 ALL cell lines and ALL clinical samples. The drug effect score (DES) was calculated from the dose-response of each drug for comparison among drugs or samples. Normal peripheral blood mononuclear cells were also applied onto the drug screening to provide the reference control values. The drug combination effect was screened based on the Bliss independent model, and validated by the improved isobologram method.

RESULTS

On sensitivity screening in a cell line panel, barasertib-HQPA which is an active metabolite of barasertib, an aurora B kinase inhibitor, alisertib, an aurora A kinase inhibitor, and YM155, a survivin inhibitor, were effective against the broadest range of ALL cells. The DES of barasertib-HQPA was significantly higher in ALL clinical samples compared to the reference value. There were significant correlations in DES between barasertib-HQPA and vincristine or docetaxel. In the drug combination assay, barasertib-HQPA and eribulin showed additive to synergistic effects.

CONCLUSION

Aurora B kinase was identified to be an active therapeutic target in a broad range of ALL cells. Combination therapy of barasertib and a microtubule-targeting drug is of clinical interest.

Drug repurposing for targeting cyclic nucleotide transporters in acute leukemias - A missed opportunity

While current treatment regimens for acute leukemia can dramatically improve patient survival, there remains room for improvement. Due to its roles in cell differentiation, cell survival, and apoptotic signaling, modulation of the cyclic AMP (cAMP) pathway has provided a meaningful target in hematological malignancies. Several studies have demonstrated that gene expression profiles associated with increased pro-survival cAMP activity or downregulation of various pro-apoptotic factors associated with the cAMP pathway are apparent in acute leukemia patients. Previous work to increase leukemia cell intracellular cAMP focused on the use of cAMP analogs, stimulating cAMP production via transmembrane-associated adenylyl cyclases, or decreasing cAMP degradation by inhibiting phosphodiesterase activity. However, targeting cyclic nucleotide efflux by ATP-binding cassette (ABC) transporters represents an unexplored approach for modulation of intracellular cyclic nucleotide levels. Preliminary studies have shown that inhibition of cAMP efflux can stimulate leukemia cell differentiation, cell growth arrest, and apoptosis, indicating that targeting cAMP efflux may show promise for future therapeutic development. Furthermore, inhibition of cyclic nucleotide transporter activity may also contribute multiple anticancer benefits by reducing extracellular pro-survival signaling in malignant cells. Hence, several opportunities for drug repurposing may exist for targeting cyclic nucleotide transporters.

"Feasible and effective administration of Bortezomib with Rituximab in children with relapsed/resistant B-cell precursor acute lymphoblastic leukemia (BCP-ALL): A step toward the first line"

Despite a high cure rate in childhood BCP-ALL, 20% of children still presents with relapse, mostly due to a persistent leukemic clone during the first-line treatment. In this context, obtaining a molecular remission is crucial for reaching a successful allogeneic hematopoietic stem cell transplantation. Bortezomib was effectively administered to children with resistant/relapsed (r/r) BCP-ALL. Moreover, high risk ALL is characterized by the increasing expression of CD20. For the first time we reported two children with r/r BCP-ALL who received a treatment schema including Bortezomib and Rituximab, achieving morphological and molecular remission. Children with high risk features, such as persistent minimal residual disease during induction, will benefit from this combination. Is it time to move toward the first line?

Bortezomib-containing therapy in Japanese children with relapsed acute lymphoblastic leukemia

Outcomes of children treated for relapsed acute lymphoblastic leukemia (ALL) remain poor. Bortezomib (BZM), a proteasome inhibitor, has shown promising activity against lymphoid malignancies. We conducted a phase I study to evaluate the safety and tolerability of multidrug chemotherapy including BZM in Japanese children with relapsed ALL. Three of five children with relapsed ALL enrolled in the study between November 2014 and April 2016 were evaluated. BZM (1.3 mg/m²) was administered on days 8, 11, 15, and 18 of multidrug induction chemotherapy. Pharmacokinetic studies were performed. Age at study entry was 5, 7, and 7 years old, respectively. Two patients had hyperdiploid B-precursor ALL, and one had T cell ALL. Although all patients experienced grade 3-4 hematologic toxicity and grade 3 elevation of aminotransferases, no dose-limiting toxicities were observed. The maximum tolerated dose was defined as 1.3 mg/m². Peripheral neuropathy and respiratory complications were not observed. Complete remission was achieved in all three patients. The mean maximum plasma concentration and area under the concentration-time curve was 74.0 ng/mL and 73.9 ng h/mL, respectively. Thus, adding BZM to 5-drug induction chemotherapy appears safe and well-tolerated in Japanese children with relapsed ALL.

PEGylated E. coli asparaginase desensitization: an effective and feasible option for pediatric patients with acute lymphoblastic leukemia who have developed hypersensitivity to pegaspargase in the absence of asparaginase Erwinia chrysanthemi availability

Asparaginase is an important component of multi-agent chemotherapy for the treatment of pediatric acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LLy). Hypersensitivity to the PEGylated form, pegaspargase, is the most common toxicity observed and is ideally addressed by substituting multiple doses of erwinia asparaginase for each subsequent dose of pegaspargase. An international shortage of erwinia asparaginase has limited the therapeutic options for those experiencing pegaspargase hypersensitivity. Here, we report pegaspargase can be safely administered, while maintaining sustained levels of asparaginase activity, to patients who have had a prior hypersensitivity reaction to pegaspargase by using a standard rapid desensitization protocol. Ten patients with prior hypersensitivity reactions to pegaspargase were treated by using a standardized rapid desensitization protocol. Eight patients had therapeutic asparaginase levels between days 4 and 7 of ≥0.05 IU/mL, and seven patients continued to have sustained levels above ≥0.1 IU/mL between days 10 and 14. Based on chemotherapy regimens, five of these patients successfully received more than one dose of pegaspargase utilizing this protocol.

Bortezomib reinduction chemotherapy in high-risk ALL in first relapse: a report from the Children's Oncology Group

While survival in paediatric acute lymphoblastic leukaemia (ALL) is excellent, survival following relapse is poor. Previous studies suggest proteasome inhibition with chemotherapy improves relapse ALL response rates. This phase 2 Children's Oncology Group study tested the hypothesis that adding the proteasome inhibitor bortezomib to chemotherapy increases complete response rates (CR2). Evaluable patients (n = 135, 103 B-ALL, 22 T-ALL, 10 T-lymphoblastic lymphoma) were treated with reinduction chemotherapy plus bortezomib. Overall CR2 rates were 68 ± 5% for precursor B-ALL patients (<21 years of age), 63 ± 7% for very early relapse (<18 months from diagnosis) and 72 ± 6% for early relapse (18-36 months from diagnosis). Relapsed T-ALL patients had an encouraging CR2 rate of 68 ± 10%. End of induction minimal residual disease (MRD) significantly predicted survival. MRD negative (MRDneg; MRD <0·01%) rates increased from 29% (post-cycle 1) to 64% following cycle 3. Very early relapse, end-of-induction MRDneg precursor B-ALL patients had 70 ± 14% 3-year event-free (EFS) and overall survival (OS) rates, vs. 3-year EFS/OS of 0-3% (P = 0·0001) for MRDpos (MRD ≥0·01) patients. Early relapse patients had similar outcomes (MRDneg 3-year EFS/OS 58-65% vs. MRDpos 10-19%, EFS P = 0·0014). These data suggest that adding bortezomib to chemotherapy in certain ALL subgroups, such as T-cell ALL, is worthy of further investigation. This study is registered at http://www.clinical.trials.gov as NCT00873093.

Panel-based next-generation sequencing identifies prognostic and actionable genes in childhood acute lymphoblastic leukemia and is suitable for clinical sequencing

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. Although the cure rate of ALL has greatly improved, a considerable number of patients suffer from relapse of leukemia. Therefore, ALL remains the leading cause of death from cancer during childhood. To improve the cure rate of these patients, precisely detecting patients with high risk of relapse and incorporating new targeted therapies are urgently needed. This study investigated inexpensive, rapid, next-generation sequencing of more than 150 cancer-related genes for matched diagnostic, remission, and relapse samples of 17 patients (3 months to 15 years old) with relapsed ALL. In this analysis, we identified 16 single-nucleotide variants (SNVs) and insertion/deletion variants and 19 copy number variants (CNVs) at diagnosis and 28 SNVs and insertion/deletion variants and 22 CNVs at relapse. With these genetic alterations, we could detect several B cell precursor ALL patients with high-risk gene alterations who were not stratified into the highest-risk group (5/8, 62.5%). We also detected potentially actionable genetic variants in about half of the patients (8/17, 47.1%). Among them, we found that one patient harbored germline TP53 mutation as a secondary finding. This inexpensive, rapid method can be immediately applied as clinical sequencing and could lead to better management of these patients and potential improvement in the survival rate in childhood ALL.

A Cryptic NUP214-ABL1 Fusion in B-cell Precursor Acute Lymphoblastic Leukemia

Fluorescent in situ hybridization (FISH) analysis is the standard methods for screening ABL1 fusions, which is recurrently translocated in pediatric acute lymphoblastic leukemia (ALL), and potentially targetable by kinase inhibitors. Here we demonstrated a case of B-cell precursor ALL with NUP214-ABL1 fusion, which break-apart FISH assay for ABL1 failed to detect. The cryptic fusion was generated by small duplication from ABL1 to NUP214, which was detected by copy number analysis using genomic microarray and confirmed by PCR. In the context of precision medicine, we should establish how to screen targetable abnormalities for minimizing risk of false-negative.

MicroRNA-326 and microRNA-200c: Two novel biomarkers for diagnosis and prognosis of pediatric acute lymphoblastic leukemia

Multidrug resistance (MDR) is considered as the major obstacle for treating pediatric acute lymphoblastic leukemia (ALL). MicroRNAs (miRNAs) are small non coding RNAs which may potentially regulate response to chemotherapy. In this study, total RNA was isolated from bone marrow samples of 46 children with de novo ALL and 16 controls. Quantitative reverse transcriptase polymerase chain reaction was used to investigate the expression profile of the predicted miRNAs; miR-326 and miR-200c, and their predicted targets ABCA2, and ABCA3 transporters. The presence of minimal residual disease was studied using PCR-SSCP (single-strand conformation polymorphism) 1 year after treatment. The association between the miRNA expression and drug resistance was analyzed statistically. Results showed a significant down-regulation of both miR-326 and miR-200c expressions in ALL patients compared with non-cancer controls (P = 0.0002, AUC = 0.813 and P = 0.035, AUC = 0.79, respectively). A considerable negative association between miR-326 expression and MDR was identified which could raise the risk of chemoresistance by 4.8- fold. The expression profiles of miR-326 and ABCA2 transporter were inversely correlated. Data revealed, a novel diagnostic role for miR-326 and miR-200c as potential biomarkers of pediatric ALL. Down-regulation of miR-326 was introduced, for the first time, as a prognostic factor for drug resistance in childhood ALL. To the best of our knowledge, this is the first time that ABCA2 transporter is proposed as a target gene for miR-326, through which it can exert its impact on drug resistance. These data may provide novel approaches to new therapeutics and diagnostics.

Treatment and biology of pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. In the past ALL was intractable but now the survival probability is as high as 80-90%. Improved supportive care, treatment stratification based on relapse risk, biological features of leukemic cells, and optimization of treatment regimens by nationwide and international collaboration have contributed to this dramatic improvement. While including traditional risk factors (e.g. age and leukocyte count at diagnosis), the treatment has been modified based on biological characteristics (aneuploidy and translocation) and treatment response (assessed by minimal residual disease). Treatment for pediatric ALL typically consists of induction therapy with steroids, vincristine, and asparaginase with or without anthracycline, followed by multi-agent consolidation including high-dose methotrexate and re-induction therapy. After consolidation, less intensive maintenance therapy is required for 1-2 years to maintain event-free survival. Recently, using advanced genomic analysis technology, novel sentinel genomic alterations that may provide more precise stratification or therapeutic targets, were identified. Moreover, in the last decade germline variations have been recognized as similarly important contributors to understanding the etiology and sensitivity of ALL to treatment. A more individualized approach based on genomic features (somatic and germline) and treatment response, the introduction of newly developed agents such as molecular targeted drugs or immunotherapy, and social support including long-term follow up are required for further improvement.

Butein inhibits cell proliferation and induces cell cycle arrest in acute lymphoblastic leukemia via FOXO3a/p27kip1 pathway

Acute lymphoblastic leukemia (ALL) is a common hematological malignancy characterized by the uncontrolled proliferation of leukemia cells in children. Discovering and developing effective chemotherapeutic drugs are needed for ALL. In this study, we investigated the anti-leukemic activity of butein and its action mechanisms in ALL. Butein was found to significantly suppress the cellular proliferation of ALL cell lines and primary ALL blasts in a dose-dependent manner. It also induced cell cycle arrest by decreasing the expression of cyclin E and CDK2. We also found that butein promoted nuclear Forkhead Class box O3a (FOXO3a) localization, enhanced the binding of FOXO3a on the p27kip1 gene promoter and then increased the expression of p27kip1. Moreover, we showed that FOXO3a knockdown significantly decreased the proliferation inhibition by butein, whereas overexpression of FOXO3a enhanced the butein-mediated proliferation inhibition. However, overexpression of FOXO3a mutation (C-terminally truncated FOXO3a DNA-binding domain) decreased the proliferation inhibition by butein through decreasing the expression of p27kip1. Our results therefore demonstrate the therapeutic potential of butein for ALL via FOXO3a/p27kip1 pathway.

Long-term outcome of 6-month maintenance chemotherapy for acute lymphoblastic leukemia in children

In the treatment of childhood acute lymphoblastic leukemia (ALL), excess shortening of maintenance therapy resulted in high relapse rate, as shown by our previous trial, TCCSG L92-13, in which maintenance therapy was terminated at 1 year from initiation of treatment. In this study, we aimed to confirm the long-term outcome of L92-13, and to identify who can or cannot be cured by shorter duration of maintenance therapy. To obtain sentinel cytogenetics information that had been missed before, we performed genetic analysis with genomic microarray and target intron-capture sequencing from diagnostic bone marrow smear. Disease-free survival (DFS) at 10 years from the end of therapy was 66.0±2.8%. Females (n=138) had better DFS (74.6±3.7%) than males (n=142, 57.5±4.2%, P=0.002). Patients with TCF3-PBX1 (n=11) and ETV6-RUNX1 (n=16) had excellent DFS (90.9±8.7% and 93.8±6.1%, respectively), whereas high hyperdiploidy (n=23) was the most unfavorable subgroup, with 56.6±10.3% of DFS. Short duration of therapy can cure more than half of pediatric ALL, especially females, TCF3-PBX1 and ETV6-RUNX1. Our retrospective observations suggest a gender/karyotype inhomogeneity on the impact of brief therapy.

Targeted delivery of vincristine to T-cell acute lymphoblastic leukemia cells using an aptamer-modified albumin conjugate

Clinical application of vincristine in treatment of cancer is restricted because of its poor solubility and neuropathy.