Treatment with all-trans retinoic acid and anthracycline monochemotherapy for children with acute promyelocytic leukemia: a multicenter study by the PETHEMA Group

Chemotherapy-free treatment for acute promyelocytic leukemia: the pediatric view of a revolutionary tale

The addition of all-trans retinoic acid (ATRA) to the standard anthracycline-base chemotherapy has revolutionized the treatment of acute promyelocytic leukemia (APL) over the last decades, becoming a model for precision medicine. The protocols based on the combination of ATRA and chemotherapy allowed obtaining excellent response rates both for children and adults. However, the persistence of anthracycline chemotherapy as a backbone was a matter of concern for both acute and long-term complications. Efforts in reducing anthracycline cumulative dose or even eliminating anthracycline have been pursued in more recent pediatric protocols thanks to the introduction of arsenic trioxide (ATO). The impressive results of the ATRA/ATO combinations led to the introduction of protocols completely chemotherapy-free for standard-risk adult patients as the standard of care, whereas pediatric chemo-free protocols are still currently under evaluation. In this Review, we will critically retrace the history of this unique revolution in precision medicine, discussing the peculiar advantages for pediatric patients with APL.

Childhood acute promyelocytic leukemia in a pediatric cancer referral center in Baghdad, Iraq. Improved results with ATRA extended consolidation

Modern treatments have dramatically improved the prognosis of childhood acute promyelocytic leukemia (APL). This progress has not yielded equivalent benefit in developing countries, where biological studies and supportive cares are insufficient and often unavailable. Since 2003, an all-trans retinoic (ATRA)-based, risk-adapted protocol was initiated in Baghdad. Patients were defined: high-risk with WBC ≥10 × 10⁹/L and standard-risk with WBC <10 × 10⁹/L. ATRA was included in induction and maintenance and, from 2010, in consolidation. Of 429 pediatric acute myeloid leukemia (September 2003-August 2019), 118 (27.5%) were APL. Six children died before therapy, 4 refused; 94/108 (87%) achieved a remission; 12 (11%) died early and 2 abandoned. The 5-year overall survival and event-free survival are 61.8% and 55.5% for all patients, 51.7% and 43.6% for first protocol, 68.4% and 63.9% for second one. Baseline WBC count was a risk factor for induction mortality; early hemorrhagic death remains a major cause of failure. ATRA extended consolidation improved results.

All-trans retinoic acid (ATRA) regulates key genes in the RARG-TOP2B pathway and reduces anthracycline-induced cardiotoxicity

The effectiveness of anthracycline chemotherapeutics (e.g., doxorubicin) is limited by anthracycline-induced cardiotoxicity (ACT). A nonsynonymous variant (S427L) in the retinoic acid receptor-γ (RARG) gene has been associated with ACT. This variant causes reduced RARG activity, which is hypothesized to lead to increased susceptibility to ACT through reduced activation of the retinoic acid pathway. This study explored the effects of activating the retinoic acid pathway using a RAR-agonist, all-trans retinoic acid (ATRA), in human cardiomyocytes and mice treated with doxorubicin. In human cardiomyocytes, ATRA induced the gene expression of RARs (RARG, RARB) and repressed the expression of topoisomerase II enzyme genes (TOP2A, TOP2B), which encode for the molecular targets of anthracyclines and repressed downstream ACT response genes. Importantly, ATRA enhanced cell survival of human cardiomyocytes exposed to doxorubicin. The protective effect of ATRA was also observed in a mouse model (B6C3F1/J) of ACT, in which ATRA treatment improved heart function compared to doxorubicin-only treated mice. Histological analyses of the heart also indicated that ATRA treatment reduced the pathology associated with ACT. These findings provide additional evidence for the retinoic acid pathway’s role in ACT and suggest that the RAR activator ATRA can modulate this pathway to reduce ACT.

Outcome and complications of pediatric acute promyelocytic leukemia in Bangladesh

Pediatric acute promyelocytic leukemia (APL) is one of the most curable subtypes of acute myeloid leukemia of childhood. But it may have many early complications, especially in developing countries. This study aims to describe the outcome and complications of pediatric APL patients in Bangladesh. This prospective observational study was conducted in the pediatric hematology and oncology department of Bangabandhu Sheikh Mujib Medical University, Dhaka from September 2017 to March 2019. In this study, PML:RAR-α (Promyelocytic leukemia-retinoic acid receptor-α) positive APL cases were included and observed while being treated with risk-directed ATRA (All-trans-retinoic acid) based chemotherapy. Among twenty PML:RAR-α positive APL cases, 13 children were in the high risk group and hemorrhagic manifestations were present in 95% of patients. Post-induction remission was achieved in 85% of the patients. 3-year overall survival was 70% (45-85% with 95% confidence interval). There was no refractory disease or relapses. Neutropenic sepsis was the most common complication and also the most common cause of mortality. In Bangladesh, the 3-year overall survival of pediatric APL is 70% (45-85% with 95% CI). Post-chemotherapy neutropenic sepsis is the most common complication and also the most common cause of mortality in this potentially curable malignancy in Bangladesh.

Analytical study of RUNX1-RUNXT1, PML-RARA, CBFB-MYH11, BCR-ABL1p210 , and KMT2-MLLT3 in Mexican children with acute myeloid leukemia: A multicenter study of the Mexican interinstitutional group for the identification of the causes of childhood leukemia (MIGICCL)

BACKGROUND

The distribution of RUNX1-RUNXT1, PML-RARA, CBFB-MYH11, BCR-ABL1^p210 , and KMT2A-MLLT3 in the pediatric population with acute myeloid leukemia (AML) in many countries of Latin America is largely unknown. Therefore, we aimed to investigate the frequency of these fusion genes in children with de novo AML from Mexico City, which has one of the highest incidence rates of acute leukemia in the world. Additionally, we explored their impact in mortality during the first year of treatment.

METHODS

We retrospectively analyzed the presence of RUNX1-RUNXT1, PML-RARA, CBFB-MYH11, BCR-ABL1^p210 , and KMT2A-MLLT3 by RT-PCR among 77 patients (<18 years) diagnosed with de novo AML between 2019 and 2021 in nine Mexico City hospitals.

RESULTS

The overall frequency of the fusion genes was 50.7%; RUNX1-RUNXT1 (22.1%) and PML-RARA (20.8%) were the most prevalent, followed by CBFB-MYH11 (5.2%) and BCR-ABL1^p210 (2.4%). KMT2A-MLLT3 was not detected. Patients with PML-RARA showed the lowest survival with high early mortality events. However, more studies are required to evaluate the impact of analyzed fusion genes on the overall survival of the Mexican child population with AML.

CONCLUSION

The pediatric population of Mexico City with AML had frequencies of AML1-ETO, PML-RARA, CBFB-MYH11, and BCR-ABL1^p210 similar to those of other populations around the world. Patients with BCR-ABL1^p210 and CBFB-MYH11 were few or did not die, while those with MLL-AF9 was not detected. Although patients with PML-RARA had a low survival and a high early mortality rate, further studies are needed to determine the long-term impacts of these fusion genes on this Latino population.

An Outcome Analysis of Childhood Acute Promyelocytic Leukemia Treated with Atra and Arsenic Trioxide, and Limited Dose Anthracycline

The overall survival of Acute Promyelocytic Leukemia (APL), reported in recent studies, is approaching to 90% wherein, arsenic trioxide (ATO) and all-trans retinoic acid (ATRA) are used as the mainstay of treatment with either limited or no use of anthracycline and cytarabine. This study is aimed to ascertain the outcome of children with APL using similar approach. A total of 30 patients with APL, registered from January 2015 to December 2018, were reviewed. Diagnosis was established on bone marrow aspirate and confirmed by the presence of PML-RARA translocation. Treatment protocol was based on Australian APML 4 study performed by Australian Leukemia Lymphoma Group (ALLG). Lumbar puncture was not performed as it was not part of the protocol due to the risk of bleeding. The mean age in current cohort was 9 years with 53% males. Seven (23.3%) patients died and three (10%) abandoned treatment during induction. Twenty patients completed the intensive phase of chemotherapy and all (100%) of them attained molecular remission (MR). One patient dropped out after MR whereas, 19 remain on follow up with no evidence of disease, reflecting disease free survival (DFS) of 95%. With a median follow up of 2.5 years (range 2.1-4.8 years) the 5 years Kaplan-Meier estimate of OS was 63% and 73%, with and without abandonment, respectively. Analysis of outcome according to risk groups revealed inferior outcome of high risk (HR) group (38% and 50% with and without abandonment, respectively) in contrast to standard risk (SR) group which showed better outcome (82% and 88% with and without abandonment, respectively). The attainment of 100% molecular remission and absence of relapse supports the effectiveness of this regimen. Moreover, it is found to be less toxic and therefore, can be conveniently managed in day-care settings.

Clinical Characteristics and Treatment Outcomes of Childhood Acute Promyelocytic Leukemia in Korea: a Nationwide Multicenter Retrospective Study by Korean Pediatric Oncology Study Group

Purpose

Acute promyelocytic leukemia (APL) is a rare disease in children and there are some different characteristics between children and adult. We aimed to evaluate incidence, clinical characteristics and treatment outcomes of pediatric APL in Korea.

Materials and Methods

Seventy-nine pediatric APL patients diagnosed from January 2009 to December 2016 in 16 tertiary medical centers in Korea were reviewed retrospectively.

Results

Of 801 acute myeloid leukemia children, 79 (9.9%) were diagnosed with APL. The median age at diagnosis was 10.6 years (range, 1.3 to 18.0). Male and female ratio was 1:0.93. Thirty patients (38.0%) had white blood cell (WBC) count greater than 10×10⁹/L at diagnosis. All patients received induction therapy consisting of all-trans retinoic acid and chemotherapy. Five patients (6.6%) died during induction chemotherapy and 66 patients (86.8%) achieved complete remission (CR) after induction chemotherapy. The causes of death were three intracranial hemorrhage, one cerebral infarction, and one sepsis. Five patients (7.1%) suffered a relapse during or after maintenance chemotherapy. The estimated 4-year event-free survival and overall survival (OS) rates were 82.1%±4.4%, 89.7%±5.1%, respectively. The 4-year OS was significantly higher in patients with initial WBC < 10×10⁹/L than in those with initial WBC ≥ 10×10⁹/L (p=0.020).

Conclusion

This study showed that the CR rates and survival outcomes in Korean pediatric APL patients were relatively good. The initial WBC count was the most important prognostic factor and most causes of death were related to serious bleeding in the early stage of treatment.

The genomics of acute myeloid leukemia in children

Acute myeloid leukemia (AML) is a clinically, morphologically, and genetically heterogeneous disorder. Like many malignancies, the genomic landscape of pediatric AML has been mapped recently through sequencing of large cohorts of patients. Much has been learned about the biology of AML through studies of specific recurrent genetic lesions. Further, genetic lesions have been linked to specific clinical features, response to therapy, and outcome, leading to improvements in risk stratification. Lastly, targeted therapeutic approaches have been developed for the treatment of specific genetic lesions, some of which are already having a positive impact on outcomes. While the advances made based on the discoveries of sequencing studies are significant, much work is left. The biologic, clinical, and prognostic impact of a number of genetic lesions, including several seemingly unique to pediatric patients, remains undefined. While targeted approaches are being explored, for most, the efficacy and tolerability when incorporated into standard therapy is yet to be determined. Furthermore, the challenge of how to study small subpopulations with rare genetic lesions in an already rare disease will have to be considered. In all, while questions and challenges remain, precisely defining the genomic landscape of AML, holds great promise for ultimately leading to improved outcomes for affected patients.

Early Mortality in Children and Adolescents with Acute Promyelocytic Leukemia: Experience of the Boldrini Children's Center

INTRODUCTION

Acute promyelocytic leukemia (APL) is currently considered a highly curable disease. However, an early death (ED) remains one of the main causes of APL treatment failure.

PATIENTS AND METHODS

In this retrospective study, we aimed to analyze the clinical characteristics of 91 children and adolescents with APL, who were consecutively registered at the (name of institution removed) Children's Center from January 1, 1998 to December 31, 2017. Data were assessed for age, sex, ethnicity, body mass index percentile, initial white blood cell count, peripheral blood blast count, and platelet count, hemoglobin value, partial thromboplastin time, prothrombin time, fibrinogen level, serum creatinine level, APL morphology subtype (classic vs. hypogranular variant M3v), and FLT3 gene mutations.

RESULTS

ED occurred in 12 of 91 (13.1%) patients and was mainly related to cerebral thromboembolism. Overall 66% of deaths occurred in the second week after diagnosis. ED was associated with white blood cell ≥10×10 cells/L (odds ratio of 8.44; 95% confidence interval [CI]=1.48-48.26; P=0.0016), initial promyelocytes ≥20×10/L (odds ratio of 9.29; 95% CI=2.45-35.8; P=0.001), morphologic subtype M3v (odds ratio of 3.63; 95% CI=1.04-12.64; P=0.043), and creatinine serum levels >0.7 mg/dL (odds ratio of 6.78; 95% CI=1.83-25.13; P=0.004). In multivariate analyses, ED was associated with initial peripheral promyelocytes ≥20×10 blasts/L and creatinine serum levels >0.7 mg/dL.

CONCLUSIONS

EDs were mainly caused by thrombohemorrhagic events and occurred within the second week after diagnosis. High peripheral promyelocytes and creatinine levels were predictors of ED in APL.

Treatment of Acute Promyelocytic Leukemia in Adults

The treatment of acute promyelocytic leukemia (APL) has evolved rapidly in the past two decades after the introduction of highly active drugs, including tretinoin (all- trans-retinoic acid) and arsenic trioxide. It is now possible to treat this disease without the use of traditional cytotoxic chemotherapy. Today’s clinical guidelines include multiple regimens, some of which continue to use cytotoxic chemotherapy. This leaves the practicing oncologist with multiple treatment options when faced with a new case of APL. In an effort to standardize our approach to the treatment of newly diagnosed APL, we sought to develop a set of treatment recommendations at our institution. We identified eight major controversial issues in the treatment of APL. These controversial issues include the optimal dose and schedule of both all- trans-retinoic acid and arsenic trioxide, the optimal regimen for high-risk APL, the need for intrathecal prophylaxis, the use of prophylactic corticosteroids, and the need for maintenance therapy after consolidation. We reviewed the relevant literature and used the Delphi method among the coauthors to reach consensus for recommendations on the basis of the best available data and our own clinical experience. In this clinical review, we present our consensus recommendations, the reasoning behind them, and the grading of the evidence that supports them.

Risk-adapted treatment of acute promyelocytic leukemia: results from the International Consortium for Childhood APL

Pediatric acute promyelocytic leukemia (APL) can be cured with all-trans retinoic acid (ATRA) and anthracycline. However, most published trials have employed high cumulative doses of anthracyclines. Here, we report the outcome of newly diagnosed APL patients enrolled in the International Consortium for Childhood APL (ICC-APL-01) trial, which reduced anthracycline exposure but extended that of ATRA. The study recruited 258 children/adolescents with molecularly/cytogenetically proven APL. Patients were stratified into standard-risk (SR) and high-risk (HR) groups according to baseline white blood cell counts (<10 × 10⁹/L or ≥10 × 10⁹/L); both groups received identical induction treatment with ATRA and 3 doses of idarubicin. Two or 3 blocks of consolidation therapy were administered to SR and HR patients, respectively, while maintenance therapy with low-dose chemotherapy and ATRA cycles was given to all patients for 2 years. The cumulative dose of daunorubicin equivalent anthracyclines in SR and HR patients was lower than that of previous studies (355 mg/m² and 405 mg/m², respectively). Hematologic remission was obtained in 97% of patients; 8 children died of intracranial hemorrhage in the first 2 weeks following diagnosis. Five-year overall and event-free survival for the whole cohort were 94.6% and 79.9%, respectively; they were 98.4% and 89.4% in SR patients and 84.3% and 74.2% in HR patients (P = .002 and P = .043, respectively). These data demonstrate that extended use of ATRA coupled to a risk-adapted consolidation can achieve high cure rates in childhood APL and limit anthracycline exposure. The trial was registered at www.clinicaltrials.gov as EudractCT 2008-002311-40.

Clinical characteristics and outcome of childhood acute promyelocitic leukemia (APL) in Saudi Arabia: a multicenter SAPHOS leukemia group study

BACKGROUND

Acute promyelocytic leukemia (APL) is a rare form of acute myelogenous leukemia (AML). Survival rates exceed 80% in developed countries. Successful treatments rely on all-trans retinoic acid with anthracycline-based chemotherapy. Availability of modern care and public knowledge play important roles in pediatric APL survival.

METHOD

A cytogenetic diagnosis of APL was confirmed in 30 (14.5%) out of 207 children consecutively diagnosed with de novo AML between January 2005 and December 2012 at nine cancer care centers in Saudi Arabia. Patients were treated based on the standard protocol used by the center following the PETHEMA or the C9710 treatment protocols. We modeled 5-year overall survival (OS), event-free survival (EFS) and cumulative incidence of relapse (CIR) vs. treatment and potential covariates of age at diagnosis, involvement of central nervous system (CNS), and white blood cell (WBC) levels.

RESULTS

The median age was 10.4 years with a male:female ratio of 1.9. WBC was 10 × 10⁹/l or greater in 57% and CNS involvement was confirmed in 13%. OS, EFS, and CIR were 74 ± 12%, 55 ± 19%, and, 36 ± 17% respectively. No significant difference was found by treatment protocol. WBC levels were significantly prognostic for all negative events, but treatment with C9710 significantly ameliorated negative WBC effects. Overall outcomes were comparable to those reported in developed countries.

CONCLUSIONS

Access to modern care is likely to be a critical factor in successful and comparable outcomes of childhood APL across the globe. In the present study, utilizing a cytarabine-containing protocol improved outcome of high-risk pediatric patients with APL.

Arsenic Trioxide Consolidation Allows Anthracycline Dose Reduction for Pediatric Patients With Acute Promyelocytic Leukemia: Report From the Children's Oncology Group Phase III Historically Controlled Trial AAML0631

Purpose The Children's Oncology Group AAML0631 trial for newly diagnosed pediatric acute promyelocytic leukemia (APL) was a phase III historically controlled trial to determine the survival of patients receiving arsenic trioxide (ATO) consolidation and reduced doses of anthracyclines. Patients and Methods Patients age 2 to 21 years with de novo APL confirmed by PML-RARα polymerase chain reaction were stratified as standard risk (SR) or high risk (HR) on the basis of diagnostic WBC count. All patients received all-trans retinoic acid (ATRA) during induction, each consolidation course, and maintenance. All patients received two cycles of ATO therapy during consolidation 1, an additional two (SR) or three (HR) consolidation courses that included high-dose cytarabine and anthracycline, and maintenance therapy comprising ATRA, oral methotrexate, and mercaptopurine. Results One hundred one patients (66 SR and 35 HR) were evaluable for outcome. The 3-year overall survival was 94%, and event-free survival (EFS) was 91%. For SR and HR patients with APL, the overall survival was 98% versus 86% ( P = .003), and EFS was 95% versus 83% ( P = .03), respectively. The EFS for SR patients in AAML0631 was noninferior to that of patients in the AIDA 0493 historical control, which used a significantly higher anthracycline dose and did not include ATO consolidation. Relapse risk for patients in AAML0631 from end consolidation 1 (after ATO treatment) was only 4% at 3 years and did not differ significantly between SR and HR patients. Conclusion ATO consolidation cycles were well tolerated in pediatric patients with APL and allowed significant reduction in cumulative anthracycline doses while maintaining excellent survival and a low relapse risk for both SR and HR patients with APL.

Recent advances in acute promyelocytic leukaemia

Acute promyelocytic leukaemia (APML) is a subtype of leukaemia arising from a distinct reciprocal translocation involving chromosomes 15 and 17, which results in the PML-RARA fusion gene. Over the past three decades, APML has been transformed from a highly fatal disease to a highly curable one. This drastic improvement is because of the introduction of a new treatment strategy with all-trans retinoic acid and, more recently, arsenic trioxide. The revolutionary treatment of APML has also paved the way for a new cancer treatment, which is genetically targeted therapy. In this review, we look into this amazing journey of transformation and provide recent advances in the management of APML.

Retinoic acid and arsenic trioxide in the treatment of acute promyelocytic leukemia: current perspectives

Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia (AML) with a unique morphological appearance, associated coagulopathy and canonical balanced translocation of genetic material between chromosomes 15 and 17. APL was first described as a distinct subtype of AML in 1957 by Dr Leif Hillestad who recognized the pattern of an acute leukemia associated with fibrinolysis, hypofibrinogenemia and catastrophic hemorrhage. In the intervening years, the characteristic morphology of APL has been described fully with both classical hypergranular and variant microgranular forms. Both are characterized by a balanced translocation between the long arms of chromosomes 15 and 17, [t(15;17)(q24;q21)], giving rise to a unique fusion gene PML-RARA and an abnormal chimeric transcription factor (PML-RARA), which disrupts normal myeloid differentiation programs. The success of current treatments for APL is in marked contrast to the vast majority of patients with non-promyelocytic AML. The overall prognosis in non-promyelocytic AML is poor, and although there has been an improvement in overall survival in patients aged <60 years, only 30%-40% of younger patients are still alive 5 years after diagnosis. APL therapy has diverged from standard AML therapy through the empirical discovery of two agents that directly target the molecular basis of the disease. The evolution of treatment over the last 4 decades to include all-trans retinoic acid and arsenic trioxide, with chemotherapy limited to patients with high-risk disease, has led to complete remission in 90%-100% of patients in trials and rates of overall survival between 86% and 97%.

Isolated Central Nervous System (CNS) Relapse in Paediatric Acute Promyelocytic Leukaemia: A Systematic Review

INTRODUCTION

Extramedullary disease, as a whole, is rare in Acute Promyelocytic Leukaemia (APML). If at all relapse occurs, following sites are involved: Central Nervous System (CNS), skin, testes, mediastinum, gingiva, and ear. Isolated CNS relapses after complete morphological and molecular remission is rarer particularly in children.

AIM

To review the literature systematically to find out the incidence of isolated CNS relapse in paediatric APML cases.

MATERIALS AND METHODS

A systematic search of major databases (Medline, Pubmed and Google Scholar) was conducted. We included all types of studies that reported about incidence or prevalence of isolated CNS relapse in children upto 18 years of age with APML.

RESULTS

A total of nine studies (with 10 cases of isolated CNS relapse) were included. Majority (70%) was high risk patients, and 60% were ≤six-year-old. Nearly, 50% were having the mean time to relapse <12 months and most (60%) of them were male. The children who died were having shorter time to CNS relapse (around 12 months), and were older (>6 to 18 years).

CONCLUSION

In the present review, disease in the high-risk group, male sex, younger age (≤six-years-old), and Promyelocytic Leukaemia/Retinoic Acid Receptor Alpha (PML-RARA) detection was found to be associated with isolated CNS relapse in children with APML. Cerebrospinal fluid (CSF) examination along with immunophenotyping and Reverse Transcription polymerase Chain Reaction (RT-PCR) for PML-RARA is required for a definite diagnosis and early treatment of patients to improve overall survival.

A 10-Year Follow-up Survey of Treatment Abandonment of Children With Acute Myeloid Leukemia in Suzhou, China

A survey of the clinical data on acute myeloid leukemia (AML) over the past 10 years in the treatment center of Children's Hospital was presented. The aim of the study was to identify the factors influencing the treatment abandonment rate (AR) of AML. Of the 474 AML cases examined, 264 were abandoned (55.7%). The most important factor affecting AR appeared to be the AML subtype-that is, the M3 versus non-M3 (42% vs. 60%). Patient age was observed to be closely related to AR-the older the patients, the lower the AR-and infants had the highest prevalence of abandonment (84.2%). The patient's residential location was markedly correlated to AR, which was almost inversely proportional to the size of the township where the patient came from. From large cities, intermediate and small towns to countryside villages, the AR increased linearly. So was the correlation with health insurance coverage, which decreased in the same way. Sex and karyotypes did not affect AR. In conclusion, the patients' financial burden and the perceived incurability of AML were the 2 leading factors dominating the decision for abandonment in parents and caregivers.

Acute myeloid leukemia in children: Current status and future directions

Acute myeloid leukemia (AML) accounts for 25% of pediatric leukemia and affects approximately 180 patients annually in Japan. The treatment outcome for pediatric AML has improved through advances in chemotherapy, hematopoietic stem cell transplantation (HSCT), supportive care, and optimal risk stratification. Currently, clinical pediatric AML studies are conducted separately according to the AML subtypes: de novo AML, acute promyelocytic leukemia (APL), and myeloid leukemia with Down syndrome (ML-DS). Children with de novo AML are treated mainly with anthracyclines and cytarabine, in some cases with HSCT, and the overall survival (OS) rate now approaches 70%. Children with APL are treated with an all-trans retinoic acid (ATRA)-combined regimen with an 80-90% OS. Children with ML-DS are treated with a less intensive regimen compared with non-DS patients, and the OS is approximately 80%. HSCT in first remission is restricted to children with high-risk de novo AML only. To further improve outcomes, it will be necessary to combine more accurate risk stratification strategies using molecular genetic analysis with assessment of minimum residual disease, and the introduction of new drugs in international collaborative clinical trials.

A coding variant in RARG confers susceptibility to anthracycline-induced cardiotoxicity in childhood cancer

Anthracyclines are used in over 50% of childhood cancer treatment protocols, but their clinical usefulness is limited by anthracycline-induced cardiotoxicity (ACT) manifesting as asymptomatic cardiac dysfunction and congestive heart failure in up to 57% and 16% of patients, respectively. Candidate gene studies have reported genetic associations with ACT, but these studies have in general lacked robust patient numbers, independent replication or functional validation. Thus, the individual variability in ACT susceptibility remains largely unexplained. We performed a genome-wide association study in 280 patients of European ancestry treated for childhood cancer, with independent replication in similarly treated cohorts of 96 European and 80 non-European patients. We identified a nonsynonymous variant (rs2229774, p.Ser427Leu) in RARG highly associated with ACT (P = 5.9 × 10(-8), odds ratio (95% confidence interval) = 4.7 (2.7-8.3)). This variant alters RARG function, leading to derepression of the key ACT genetic determinant Top2b, and provides new insight into the pathophysiology of this severe adverse drug reaction.

Acute promyelocytic leukemia in children and adolescents

Acute promyelocytic leukemia (APL) is a rare subtype of AML characterized by a reciprocal balanced translocation between chromosomes 15 and 17 that fuses the PML gene with the RARα gene and leads to the leukemic phenotype. Although best described in large clinical trials of adults, APL, like other forms of AML, also occurs in children. The positive outcome of children with APL mirrors the dramatic increase in survival seen in adults since the introduction of all-trans retinoic acid (ATRA). In this paper, we review the diagnosis of APL in children as well as large, retrospective, clinical trial data collected on pediatric APL. We also raise management issues and toxicities that are unique to children.

Treatment of paediatric APL: how does the therapeutic approach differ from adults?

Acute promyelocytic leukaemia (APL) in children and adolescents shares many features with APL in adults. There are important distinctions, however, between these age groups in the presentation, complications and treatment outcomes. Paediatric patients are more likely to present with high risk features including elevated WBC count or microgranular variant (M3v). Yet the early death rate is lower in paediatric patients compared to adult patients. Overall outcomes such as CR, OS and EFS appear similar in paediatric and adult patients treated on similar regimens except that very young children may have a higher risk of relapse. While contemporary studies have clearly demonstrated improved survival in adults receiving ATO therapy, currently there is more limited data on the role of ATO in paediatric patients. Here we highlight the similarities and important distinctions between paediatric and adult APL while reviewing available data on treatment of paediatric APL.

Acute Promyelocytic Leukemia (APL): Comparison Between Children and Adults

The outcome of adults and children with Acute Promyelocytic Leukemia (APL) has dramatically changed since the introduction of all trans retinoic acid (ATRA) therapy. Based on the results of several multicenter trials, the current recommendations for the treatment of patients with APL include ATRA and anthracycline-based chemotherapy for the remission induction and consolidation, and ATRA combined with low-dose chemotherapy for maintenance. This has improved the prognosis of APL by increasing the complete remission (CR) rate, actually > 90%, decreasing the induction deaths and by reducing the relapse rate, leading to cure rates nowadays exceeding 80% considering both adults and children.1-9 More recently the combination of ATRA and arsenic trioxide (ATO) as induction and consolidation therapy has been shown to be at least not inferior and possibly superior to ATRA plus chemotherapy in adult patients with APL conventionally defined as non-high risk (Sanz score).10 Childhood APL has customarily been treated on adult protocols. Data from several trials have shown that the overall outcome in pediatric APL appears similar to that reported for the adult population; however, some clinical and therapeutic aspects differ in the two cohorts which require some important considerations and treatment adjustments.

Advances in paediatric cancer treatment

Four out of five children diagnosed with cancer can be cured with contemporary cancer therapy. This represents a dramatic improvement since 50 years ago when the cure rate of childhood cancer was <25% in the pre-chemotherapy era. Over the past ten years, while improvement in overall survival (OS) has been marginal, progress in pediatric oncology lies with adopting risk-adapted therapeutic approach. This has been made possible through identifying clinical and biologic prognostic factors with rigorous research and stratifying patients using these risk factors, and subsequently modifying therapy according to risk group assignment. This review provides a perspective for eight distinct pediatric malignancies, in which significant advances in treatment were made in the last decade and are leading to changes in standard of care. This includes four hematologic malignancies [acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL)] and four solid tumors [medulloblastoma (MB), low grade glioma (LGG), neuroblastoma (NB) and Ewing sarcoma (ES)]. Together, they comprise 60% of childhood cancer. Improved patient outcome is not limited to better survival, but encompasses reducing both short and long-term treatment-related complications which is as important as cure, given the majority of childhood cancer patients will become long-term survivors. Risk-adapted approach allows treatment intensification in the high-risk cohort while therapy can be de-escalated in the low-risk to minimize toxicity and late sequelae without compromising survival. Advances in medical research technology have also led to a rapid increase in the understanding of the genetics of childhood cancer in the last decade, facilitating identification of molecular targets that can potentially be exploited for therapeutic benefits. As we move into the era of targeted therapeutics, searching for novel agents that target specific genetic lesions becomes a major research focus. We provide an overview of seven novel agents (bevacizumab, bortezomib, vorinostat, sorafenib, tipifarnib, erlotinib and mTOR inhibitors), which have been most frequently pursued in childhood cancers in the last decade, as well as reporting the progress of clinical trials involving these agents.

Induction mortality, ATRA administration, and resource utilization in a nationally representative cohort of children with acute promyelocytic leukemia in the United States from 1999 to 2009

BACKGROUND

Limited data exist on induction mortality of pediatric patients with acute promyelocytic leukemia in the United States, usage of all-trans retinoic acid (ATRA) during acute promyelocytic leukemia induction, and the resources needed to deliver induction therapy.

PROCEDURE

Using the Pediatric Health Information System database we established a retrospective cohort of patients treated for newly diagnosed acute promyelocytic leukemia with ATRA between January 1999 and September 2009 in 32 of 43 PHIS contributing free-standing pediatric hospitals in the United States. Standard statistical methods were used to determine in-hospital induction mortality, ATRA administration, and resource utilization during a 60-day observation period.

RESULTS

A total of 163 children were identified who met eligibility criteria for cohort inclusion; 52% were female and 76% were white with an average age of 12.7 years. A total of 12 patients (7.4%) died, with 7 (58.3%) dying within the first 7 days of first admission. The mean time to first ATRA exposure increased with decreasing age (P = 0.0016). Resource utilization for management of retinoic acid syndrome was higher than anticipated based on prior studies and differed significantly from patients with non-M3 acute myeloid leukemia.

CONCLUSIONS

The induction mortality for pediatric acute promyelocytic leukemia remains substantial with wide variation in ATRA administration and high rates of resource utilization.

How I treat children and adolescents with acute promyelocytic leukaemia

Acute promyelocytic leukaemia (APL) is a rare subtype of acute myeloid leukaemia. The outcome of paediatric APL has improved substantially over the past 20 years; cure rates above 80% are expected when all-trans retinoic acid (ATRA) is given with anthracycline-based regimens. The presenting features of paediatric APL may include severe bleeding and thrombotic complications, which contribute to the high early death rate. The incidence of leucocytosis and the microgranular subtype is greater in paediatric than adult APL, and children experience greater ATRA-related toxicity. It is crucial to begin ATRA therapy and intensive platelet and fibrinogen replacement on first suspicion of APL. Recent risk-adapted therapeutic trials have shown that patients at greater risk of relapse benefit from the introduction of high-dose cytarabine during consolidation. Combination therapy with ATRA and arsenic trioxide provides very effective frontline treatment and may reduce the need for subsequent anthracycline therapy.

Long-term prognosis of childhood acute promyelocytic leukaemia with arsenic trioxide administration in induction and consolidation chemotherapy phases: a single-centre experience

OBJECTIVES

The efficacy of all-trans retinoic acid (ATRA) and arsenic trioxide (As2 O3 ) as induction therapy for adult acute promyelocytic leukaemia (APL) has been documented in several clinical trials. However, the role of ATRA/As2 O3 combination in induction and consolidation therapy in children remains unclear. Here, we report the efficacy of combined treatment with As2 O3 and ATRA as induction and consolidation chemotherapy to treat newly diagnosed childhood APL.

METHODS

From 1998 to 2011, 43 children with newly diagnosed APL received induction and consolidation chemotherapy with ATRA and As2 O3 (Protocol B). Rates of complete remission (CR), event-free survival (EFS), disease-free survival (DFS), and overall survival (OS) and drug toxicity were compared between children treated with Protocol B and 25 others treated previously with ATRA alone as induction chemotherapy (Protocol A).

RESULTS

Of 43 patients treated with Protocol B, 41 (95.4%) achieved CR (two died of intracranial haemorrhage on day 10 and 14). In contrast, only 20 (80%) of 25 patients treated with Protocol A achieved CR. Thus, the CR rate was significantly lower in patients receiving induction chemotherapy with Protocol A than in those treated with Protocol B (P = 0.045, χ(2) = 6.508). Of the 41 patients who achieved CR on induction therapy with Protocol B, 40 also received consolidation therapy. Molecular relapse, but no overt morphological relapse, occurred in one patient at 25 months after diagnosis; this patient regained CR status with As2 O3 treatment. With a median follow-up period of 75 months, estimated EFS, DFS and OS rates were 92.5 ± 4.2%, 97.1 ± 2.9% and 95.3 ± 3.2%, respectively, for Protocol B. In contrast, with a median follow-up of 127 months, the EFS, DFS and OS rates at 75 months were 70.4 ± 9.4%, 76.4 ± 9.2% and 70.4 ± 9.4%, respectively, for Protocol A. Thus, patients treated with Protocol A showed significantly lower EFS (P = 0.021) and OS (P = 0.007) rates than those treated with Protocol B.

CONCLUSIONS

Application of As2 O3 and ATRA as induction and consolidation chemotherapy resulted in excellent outcomes and improved long-term prognosis in children with newly diagnosed APL.

Role of long non-coding RNAs in normal and malignant hematopoiesis

Long non-coding RNAs (lncRNAs) are defined as a class of nonprotein-coding transcripts greater than 200 nucleotides in length, which have diverse functions in development and diseases including hematopoiesis. Recent advances have revealed that lncRNAs regulate hematopoietic development at almost every stage, including differentiation of the myelocyte, lymphocyte, and erythrocyte. Abnormal regulation of the lncRNAs may block aspects of blood development, which can lead to different types of hematopoietic disorders. These findings highlight the role of lncRNAs as potential therapeutic tools in malignant hematopoiesis. In this review, we summarize recent progress in the study of functional lncRNAs associated with blood development, as well as dysregulated lncRNAs involved in diverse blood diseases by interacting with crucial susceptibility genes in different pathways. In addition, we discuss genome-wide studies on lncRNAs, which are helpful for genome screening and in-depth functional study of lncRNAs associated with blood development and disease.

Long term curative effects of sequential therapy with all-trans retinoic acid, arsenious oxide and chemotherapy on patients with acute promyelocytic leukemia

BACKGROUND

Both all-trans retinoic acid (ATRA) and arsenic trioxide (As(2)O(3)) have proven to be very effective in obtaining high clinical complete remission (CR) rates in acute promyelocytic leukemia (APL).

METHODS

In this study, 73 newly diagnosed APL subjects were treated with an ATRA and As(2)O(3) combination treatment in remission induction and post remission therapy. Tumor burden was examined with PCR of the PML-RAR fusion transcripts, and side effects were evaluated by means of clinical examination.

RESULTS

The results showed that ATRA/As(2)O(3) combination therapy yielded a CR rate of 94.5% (69/73) with a shorter time to enter CR (median: 27 days; range: 21-43 days). Four cases failed to enter CR; three of these died of cerebral hemorrhage and disseminated intravascular coagulation (DIC) within 72 hours of starting induction therapy, one older patient died of severe pulmonary infection. The early death rate was 5.5% (4/73). All 69 cases that obtained CR remained in good clinical remission after a follow-up of 35-74 months (median: 52 months).The drug toxicity profile with the use of As(2)O(3) showed mainly hepatotoxicity. Liver dysfunction was slight in most cases. There were no severe side effects in long term follow-up.

CONCLUSION

We conclude that APL patients may benefit from the use of the combination of ATRA and As(2)O(3) in either remission induction or consolidation/maintenance.

The role of maintenance therapy in acute promyelocytic leukemia in the first complete remission

BACKGROUND

Acute promyelocytic leukemia (APL) is the most curable type of leukemia. A consensus exists regarding the need for administration of both induction and consolidation treatments, albeit using different approaches. However, there is conflicting evidence for the role of maintenance treatment in APL patients.

OBJECTIVES

To examine the efficacy and safety of maintenance therapy in APL patients and to establish the optimal regimen for maintenance.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 6), MEDLINE (January 1966 to July 2012), LILACS (1982 to July 2012), relevant conference proceedings (2000 to 2012) and databases of ongoing and unpublished trials.

SELECTION CRITERIA

Randomized controlled trials assessing maintenance treatment in patients with newly diagnosed APL in first complete remission (CR) following induction or induction and consolidation therapy.

DATA COLLECTION AND ANALYSIS

Two review authors assessed the quality of trials and extracted data. We estimated and pooled hazard ratios (HR) and risk ratios (RR) with 95% confidence intervals (CI) using the fixed-effect model. If significant heterogeneity was present we explored potential causes for such heterogeneity and if not found we used also the random-effects model.

MAIN RESULTS

We included 10 randomized controlled trials enrolling 2072 patients in the systematic review, and conducted meta-analysis on nine of them. There was no statistically significant effect on overall survival (OS) in the three main comparisons (HR for any maintenance treatment versus observation 0.79, 95% CI 0.49 to 1.27; HR for all-trans retinoic acid (ATRA)-based maintenance versus non-ATRA based maintenance 1.21, 95% CI 0.73 to 1.98; HR for ATRA alone maintenance versus ATRA and chemotherapy 0.99, 95% CI 0.69 to 1.43). However, disease free survival (DFS) was improved with any maintenance therapy compared to observation (HR 0.59, 95% CI 0.48 to 0.74; 5 trials, 1209 patients) and with ATRA and chemotherapy compared to ATRA alone maintenance (HR for ATRA alone compared to ATRA and chemotherapy 1.38, 95% CI 1.09 to 1.76; 4 trials, 1028 patients). DFS was not improved with ATRA-based regimens compared to non-ATRA based regimens (HR 0.72, 95% CI 0.51 to 1.01; 4 trials, 670 patients). Analysis of clinically relevant adverse events could not be conducted due to paucity of data. Yet, increased reports of grade 3/4 adverse events were noted for any maintenance versus observation and for combined ATRA and chemotherapy versus ATRA alone treatment. The major limitation of this review lies in the variability between the included trials in both maintenance and pre-maintenance parameters. We tried to address this variability and to reduce its potential biases by conducting three separate main comparisons, as outlined above, leaving less statistical power to the presented results.

AUTHORS' CONCLUSIONS

Maintenance therapy compared to observation in APL patients improved DFS but not OS. Similarly, ATRA and chemotherapy compared to ATRA improved DFS but not OS. In contrast, ATRA based regimens compared to non-ATRA based regimens did not demonstrate a survival benefit. The significance of these findings is limited due to clinical heterogeneity between studies.

All-trans retinoic acid in the treatment of pediatric acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is a rare form of acute myeloid leukemia with specific epidemiological, pathogenetic and clinical features. Its frequency varies widely among nations, with a decreased incidence among 'Nordic' origin populations. The molecular hallmark of the disease is the presence of a balanced reciprocal translocation resulting in the PML/RAR-α gene fusion, which represents the target of the all-trans retinoic acid (ATRA) therapy. The introduction of ATRA in conjunction with anthracyclines marked a turning point in the treatment of APL, previously associated with a significant morbidity and mortality. Nowadays the standard front-line therapy for pediatric APL includes ATRA in every phase of the treatment, resulting in a complete remission rate of 90-95%. Here we provide an overview of the role of ATRA in the treatment of pediatric APL, summarizing the most relevant clinical results of recent decades and investigating future therapeutic perspectives for children with APL.

Retinoids in pediatric onco-hematology: the model of acute promyelocytic leukemia and neuroblastoma

Retinoids are lipophilic compounds derived from vitamin A, which have been extensively studied in cancer prevention and therapy. In pediatric oncology, they are successfully used for the treatment of acute promyelocytic leukemia (APL) and high-risk neuroblastoma (HR-NBL). APL is a subtype of acute myeloid leukemia (AML) clinically characterized by a severe bleeding tendency with a highrisk of fatal hemorrhage. The molecular hallmark of this disease is the presence of the promyelocytic leukemia (PML)-retinoic acid receptor-α (RAR α) gene fusion that plays a critical role in promyelocytic leukemogenesis and represents the target of retinoid therapy. The introduction in the late 1980s of all-trans retinoic acid (ATRA) into the therapy of APL radically changed the management and the outcome of this disease. Presently, the standard front-line therapeutic approach for pediatric APL includes anthracycline-based chemotherapy and ATRA, leading to a complete remission in almost 90% of the patients. Neuroblastoma (NBL) is an aggressive childhood tumor derived from the peripheral neural crest. More than half of patients have a high-risk disease, with a poor outcome despite intensive multimodal treatment. Although the exact mechanism of action remains unclear, the introduction of 13-cis-retinoic acid (13-cis-RA) in the therapy of NBL has improved the prognosis of this disease. Currently, the standard treatment for HR-NBL consists of myeloablative therapy followed by autologous hematopoietic stem cell transplantation (HSCT) and maintenance with 13-cis-RA for the treatment of minimal residual disease, leading to a 3-year disease-free survival rate (DFS) of about 50%. In this paper the authors provide a review of the peer-reviewed literature on the role of retinoids in the treatment of pediatric APL and HR-NBL, summarizing the most relevant clinical trial results of the last decades, analyzing the ongoing trials, and investigating future therapeutic perspectives of children affected by these diseases.

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

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

Retrospective analysis of 119 cases of pediatric acute promyelocytic leukemia: Comparisons of four treatment regimes

Clinical trials have demonstrated that pediatric acute promyelocytic leukemia (APL) is highly curable. Small-scale studies have reported on the treatment of APL using one or two treatment regimes. Here, we report a multiple center-based study of 119 cases of pediatric APL treated with four regimes based on all-trans-retinoic acid (ATRA). We retrospectively analyzed the clinical characteristics, laboratorial test results and treatment outcome of the pediatric APL patients. Regime 1 used an in-house developed protocol, regime 2 was modified from the PETHEMA LPA99 protocol, regime 3 was modified from the European-APL93 protocol, and regime 4 used a protocol suggested by the British Committee for Standards in Haematology. The overall complete remission rates for the four regimes were 88.9, 87.5, 97.1 and 87.5%, respectively, which exhibited no statistical difference. However, more favorable results were observed for regimes 2 and 3 than regimes 1 and 4, in terms of the estimated 3.5-year disease-free survivals, relapse rates, drug toxicity (including hepatotoxicity, cardiac arrhythmia, and differentiation syndrome) and sepsis. In conclusion, the overall outcomes were more favorable after treatment with regimes 2 and 3 than with regimes 1 and 4, and this may have been due to the specific compositions of regimes 2 and 3.

Outcome of acute promyelocytic leukemia (APL) in children and adolescents: an analysis in two consecutive trials of the European APL Group

PURPOSE

Acute promyelocytic leukemia (APL) is rare in children. All-trans-retinoic acid (ATRA) combined with chemotherapy, the reference treatment of APL, is generally considered to produce similar results in children and adults. However, previously published childhood APL studies have generally analyzed all patients age < 18 years as a group, without further dividing according to age.

PATIENTS AND METHODS

We compared disease characteristics and outcomes of children (age ≤ 12 years), adolescents (13 to 18 years), and adults (> 18 years) included in two multicenter APL clinical trials (APL 93 and 2000 trials).

RESULTS

Of the 833 patients age ≤ 60 years included in the two trials, 26 (3%), 58 (7%), and 749 (90%) were children, adolescents, and adults, respectively. Children had significantly higher baseline WBC counts (P < .001). The complete remission (CR) rate (92%, 100%, and 94.5%, respectively) and 5-year cumulative incidence of relapse (CIR; 28%, 20%, and 23%, respectively) did not differ between children, adolescents, and adults, whereas adolescents had significantly better overall survival (OS; 5-year OS, 93.6% v 80.4% in adults and 80.4% in children; P = .03). However, in children age ≤ 4 years, the 5-year CIR was 52%, compared with 17.6% in children age 5 to 12 years (P = .006), although most of the younger children who relapsed experienced durable salvage with autologous or allogeneic stem-cell transplantation.

CONCLUSION

Adolescents and children age > 4 years with APL treated with ATRA and chemotherapy have outcomes at least as favorable as those of adults. Younger children seem to experience more relapses and may require reinforcement of first-line treatment.

Oral arsenic trioxide for relapsed acute promyelocytic leukemia in pediatric patients

Four patients (age 3-11 years at diagnosis) with relapsed acute promyelocytic leukemia (APL), 12-38 months from diagnosis, were treated with oral arsenic trioxide (As(2) O(3) ). One patient was treated with oral As(2) O(3) monotherapy and chemotherapy. Three patients failed initial oral or intravenous As(2) O(3) monotherapy were treated with oral As(2) O(3) plus ATRA followed by long-term oral maintenance (cumulative As(2) O(3) dose 280-2,100 mg). All patients achieved molecular remission, at a median follow up of 122 (10-132) months with no adverse effects. Oral As(2) O(3) , particularly in prolonged maintenance with oral ATRA may obviate the need of stem cell transplantation in relapsed pediatric APL.

Epidemiology, diagnosis and treatment of acute promyelocytic leukemia in children: the experience in china

Acute promyelocytic leukemia (APL) is the subtype of acute myeloid leukemia characterized by an accumulation of abnormal promyelocytes in bone marrow, a severe bleeding tendency and the presence of the chromosomal translocation t(15;17) or variants. APL, the most fatal type of leukemia two decades ago, is highly curable with current treatment strategies. There is evidence that the incidence of APL varies across ethnic groups and that genetic factors play a role in the etiology of APL. And there are some difference between children and adults in APL.1-3 The limited data of children available in many developing countries suggest that the rate of early mortality is high and that long-term survival is poor. Death from bleeding and infection during chemotherapy, relapse and treatment abandonment are among the main cause of treatment failure in APL children as well in adults.2 The status of children APL treatment in China has not been described in general.Here we describe the epidemiology and treatment of APL in children in China. In addition, we review the results of a survey of its clinical manifestations and outcome in China.

Rapid downregulation of cyclin D1 induced by geranylgeranoic acid in human hepatoma cells

Geranylgeranoic acid (GGA) and its derivatives are currently under development as chemopreventive agents against second primary hepatoma in Japan. We aimed to evaluate chemoprevention targets of GGA and a surrogate marker of chemopreventive response to clarify the molecular mechanism of hepatoma chemoprevention with GGA. Human hepatoma-derived cell lines such as HuH-7, PLC/PRF/5, and HepG-2, were treated with GGA and its derivatives. Cellular dynamics of several cell-cycle-related proteins were assessed by either immunoblotting or immunofluorescence method. The cellular expression of cyclin D1 protein was suppressed immediately after GGA treatment. This reduction was partially blocked by pretreatment with 26S proteasome inhibitor MG-132, indicating that proteasomal degradation was involved in GGA-induced disappearance of cyclin D1. A phosphorylation of retinoblastoma protein (RB) at serine 780, a target site of cyclin D1-dependent kinase 4, was rapidly decreased in GGA-treated HuH-7 cells. Furthermore, subcellular fractionation, Western blotting, and immunofluorescence revealed GGA-induced nuclear accumulation of RB. These results strongly suggest that cyclin D1 may be a target of chemopreventive GGA in human hepatoma cells. GGA-induced rapid repression of cyclin D1, and a consequent dephosphorylation and nuclear translocation of RB, may influence cell cycle progression and may be relevant to GGA-induced cell death mechanisms.

Treatment of acute promyelocytic leukemia with high white cell blood counts

Acute promyelocytic leukemia (APL) with WBC above 10 G/L has long been considered, even in the all-trans retinoic acid (ATRA) era, to carry a relatively poor prognosis (compared to APL with WBC below 10 G/L), due to increased early mortality and relapse. However, early deaths can to a large extent be avoided if specific measures are rapidly instigated, including prompt referral to a specialized center, immediate onset of ATRA and chemotherapy, treatment of coagulopathy with adequate platelet transfusional support, and prevention and management of differentiation syndrome. Strategies to reduce relapse rate include chemotherapy reinforcement with cytarabine and/or arsenic trioxide during consolidation, prolonged maintenance treatment, especially with ATRA and low dose chemotherapy, and possibly, although this is debated, intrathecal prophylaxis to prevent central nervous system relapse. By applying those measures, outcomes of patients with high risk APL have considerably improved, and have become in many studies almost similar to those of standard risk APL patients.

Upregulation of microRNA-125b contributes to leukemogenesis and increases drug resistance in pediatric acute promyelocytic leukemia

Background

Although current chemotherapy regimens have remarkably improved the cure rate of pediatric acute promyelocytic leukemia (APL) over the past decade, more than 20% of patients still die of the disease, and the 5-year cumulative incidence of relapse is 17%. The precise gene pathways that exert critical control over the determination of cell lineage fate during the development of pediatric APL remain unclear.

Methods

In this study, we analyzed miR-125b expression in 169 pediatric acute myelogenous leukemia (AML) samples including 76 APL samples before therapy and 38 APL samples after therapy. The effects of enforced expression of miR-125b were evaluated in leukemic cell and drug-resistant cell lines.

Results

miR-125b is highly expressed in pediatric APL compared with other subtypes of AML and is correlated with treatment response, as well as relapse of pediatric APL. Our results further demonstrated that miR-125b could promote leukemic cell proliferation and inhibit cell apoptosis by regulating the expression of tumor suppressor BCL2-antagonist/killer 1 (Bak1). Remarkably, miR-125b was also found to be up-regulated in leukemic drug-resistant cells, and transfection of a miR-125b duplex into AML cells can increase their resistance to therapeutic drugs,

Conclusions

These findings strongly indicate that miR-125b plays an important role in the development of pediatric APL at least partially mediated by repressing BAK1 protein expression and could be a potential therapeutic target for treating pediatric APL failure.

Recent advances in the diagnosis and management of childhood acute promyelocytic leukemia

Since the successful introduction of all-trans-retinoic acid (ATRA) and its combination with anthracycline-containing chemotherapy, the prognosis for acute promyelocytic leukemia (APL) has markedly improved. With ATRA and anthracycline-based-chemotherapy, the complete remission rate is greater than 90%, and the long-term survival rate is 70-89%. Moreover, arsenic trioxide (ATO), which was introduced for APL treatment in 1994, resulted in excellent remission rates in relapsed patients with APL, and more recently, several clinical studies have been designed to explore its role in initial therapy either alone or in combination with ATRA. APL is a rare disease in children and is frequently associated with hyperleukocytosis, which is a marker for higher risk of relapse and an increased incidence of microgranular morphology. The frequency of occurrence of the promyelocytic leukemia/retinoic acid receptor-alpha (PML/RARα) isoforms bcr 2 and bcr 3 is higher in children than in adults. Although recent clinical studies have reported comparable long-term survival rates in patients with APL, therapy for APL in children is challenging because of the risk of early death and the potential long-term cardiac toxicity resulting from the need to use high doses of anthracyclines. Additional prospective, randomized, large clinical trials are needed to address several issues in pediatric APL and to possibly minimize or eliminate the need for chemotherapy by combining ATRA and ATO. In this review article, we discuss the molecular pathogenesis, diagnostic progress, and most recent therapeutic advances in the treatment of children with APL.