Childhood acute leukemia: a single institution experience in La Plata, Argentina

Acute Promyelocytic Leukemia in Children: A Model of Precision Medicine and Chemotherapy-Free Therapy

Acute promyelocytic leukemia (APL) represents a paradigm of precision medicine. Indeed, in the last decades, the introduction of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) completely revolutionized the therapeutic approach to this previously highly fatal disorder. This entirely chemotherapy-free treatment, which provided excellent survival rates, has been initially validated in adults and, recently, translated in the pediatric setting. This review summarizes currently available data on the use of ATRA and ATO combination in pediatric APL, providing a particular focus on peculiar issues and challenges, such as the occurrence of pseudotumor cerebri and death during induction (early death), as well as the advantage offered by the ATO/ATRA combination in sparing long-term sequelae.

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.

Global characteristics of childhood acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) comprises approximately 5-10% of childhood acute myeloid leukemia (AML) cases in the US. While variation in this percentage among other populations was noted previously, global patterns of childhood APL have not been thoroughly characterized. In this comprehensive review of childhood APL, we examined its geographic pattern and the potential contribution of environmental factors to observed variation. In 142 studies (spanning >60 countries) identified, variation was apparent-de novo APL represented from 2% (Switzerland) to >50% (Nicaragua) of childhood AML in different geographic regions. Because a limited number of previous studies addressed specific environmental exposures that potentially underlie childhood APL development, we gathered 28 childhood cases of therapy-related APL, which exemplified associations between prior exposures to chemotherapeutic drugs/radiation and APL diagnosis. Future population-based studies examining childhood APL patterns and the potential association with specific environmental exposures and other risk factors are needed.

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.

Management of acute promyelocytic leukemia: recommendations from an expert panel on behalf of the European LeukemiaNet

The introduction of all-trans retinoic acid (ATRA) and, more recently, arsenic trioxide (ATO) into the therapy of acute promyelocytic leukemia (APL) has revolutionized the management and outcome of this disease. Several treatment strategies using these agents, usually in combination with chemotherapy, but also without or with minimal use of cytotoxic agents, have provided excellent therapeutic results. Cure of APL patients, however, is also dependent on peculiar aspects related to the management and supportive measures that are crucial to counteract life-threatening complications associated with the disease biology and molecularly targeted treatment. The European LeukemiaNet recently appointed an international panel of experts to develop evidence- and expert opinion-based guidelines on the diagnosis and management of APL. Together with providing current indications on genetic diagnosis, modern risk-adapted front-line therapy and salvage treatment, the review contains specific recommendations for the identification and management of most important complications such as the bleeding disorder, APL differentiation syndrome, QT prolongation and other ATRA- and ATO-related toxicities, as well as for molecular assessment of response to treatment. Finally, the approach to special situations is also discussed, including management of APL in children, elderly patients, and pregnant women.

A comprehensive review of acute promyelocytic leukemia in children

The outcome of patients with acute promyelocytic leukemia (APL) has substantially improved since the successful introduction of tretinoin, and nowadays combining tretinoin with chemotherapy is potentially curative for at least 70-75% of patients with newly diagnosed APL. In most pediatric series, APL represents < or = 10% of childhood acute myelogenous leukemia. APL in children is more common in girls and in obese children. It is characterized by a higher incidence of hyperleukocytosis, an increased incidence of microgranular morphology and by more frequent occurrence of the PML/RARalpha isoforms bcr 2 and bcr 3 compared to adults. Tretinoin-based therapy is curative for the majority of children with APL. Recent data indicate that > or = 2 negative RT-PCR assays for PML/RARalpha on bone marrow performed at least 1 month apart after completing therapy are strongly associated with long-term remissions, while conversion to PCR positivity for PML/RARalpha during remission is highly predictive of impending relapse. Data from recent studies in adults and limited data from children show that arsenic trioxide is the single most effective agent in APL and deserves immediate study in newly diagnosed children in an effort to further improve prognosis and to limit exposure to conventional cytotoxic chemotherapy.

Acute promyelocytic leukaemia in children

Acute promyelocytic leukaemia (APL), designated M3, is a particularly interesting subtype of acute myeloid leukaemia (AML) that has unique molecular and clinical characteristics. It is characterized by an arrest of myeloid differentiation at the promyelocyte stage with abnormal proliferation of these cells. Recent paediatric and adult trials which included all-trans retinoic acid (ATRA) have shown that APL has significantly better survival rates than other subtypes of AML. While there is extensive literature on APL in adults, articles dedicated to describing solely paediatric patients are limited. This chapter focuses on the incidence, diagnosis, clinical characteristics, treatment, and survival rates of children with APL.