A comprehensive review of acute promyelocytic leukemia in children

A Case of Subacute Brain Hemorrhage and Disseminated Intravascular Coagulation Secondary to Acute Promyelocytic Leukemia in a Pediatric Patient

Acute promyelocytic leukemia (APML), characterized by the reciprocal translocation between chromosomes 15 and 17 [t(15;17)], is a result of proliferation of myeloid cells maturation which is interrupted at the promyelocytic stage. The central, and the most important, distinguishing feature of APML is a predisposition to disseminated intravascular coagulation (DIC). The overall prognosis of APML is very good, with 90% of patients achieving complete remission. We find it important to remind pediatric practitioners, both in the ambulatory and urgent care room settings, of presenting signs and symptoms of leukemia, as well as, up-to-date on management of such fulminant scenarios as DIC. Intracranial hemorrhage (ICH) is one of the commonest, and frequently fulminant complication of APML seen after initiation of induction chemotherapy. We report on a young female presenting with non-specific upper respiratory illness symptoms and recurrent headache, who was found to already have ICH and to be in DIC in the setting of APML at the time of initial evaluation. This case illustrates importance of thorough assessment and prompt consideration of wide differential diagnosis, which became somewhat limited and biased towards web-based telemedicine in the COVID-19 pandemics era.

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.

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.

Pediatric Acute Promyelocytic Leukemia Presenting to the Emergency Department as Refusal to Ambulate

A previously healthy 10-year-old girl presented to the emergency department (ED) with a headache and vomiting which resolved with oral NSAIDs. The patient returned two days later unable to ambulate with mental slowing and lower extremity bruising. Labs demonstrated marked leukocytosis, severe anemia and thrombocytopenia, and disseminated intravascular coagulation (DIC). Brain MRI showed multiple intracranial hemorrhages. A peripheral blood smear demonstrated blasts with many Auer rods. A diagnosis of acute promyelocytic leukemia (APL) was made and therapy including all-transretinoic acid (ATRA) was initiated. Neurologic status returned to baseline within 1 week in the pediatric intensive care unit.

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.

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.

Treatment of an acute promyelocytic leukemia relapse using arsenic trioxide and all-trans-retinoic in a 6-year-old child

In adult therapy, arsenic trioxide (ATO) and all-trans-retinoic acid (ATRA) are recognized as active treatment of relapsed acute promyelocytic leukemia (APL). The efficacy of this combination in pediatric APL has not yet been well established. We report the case of a 6-year-old girl with relapsed APL, with a PML-RARα mutation, treated with a combination of ATO and ATRA. Over a period of 5 months, she received in total, 75 doses of intravenous ATO and 40 doses of oral ATRA. Currently, 22 months after relapse, she is still in complete remission. Here, we describe treatment of a relapsed APL in a child with limited treatment of ATO and ATRA and review the literature.

Cytogenetic abnormalities and monosomal karyotypes in children and adolescents with acute myeloid leukemia: correlations with clinical characteristics and outcome

The whole spectrum of chromosomal abnormalities and their prognostic significance in children and adolescents with acute myeloid leukemia (AML) has not been fully elucidated yet, although a considerable amount of knowledge has been gained recently. Moreover, the incidence and prognostic impact of monosomal karyotypes (MKs), which are new cytogenetic categories reported recently in adults with AML, are currently unknown for childhood and adolescent AML. In this study, we investigated the cytogenetic and clinical characteristics of 140 children and adolescents (≤21 y) with AML, and correlated their cytogenetic features with both the clinical characteristics and outcomes of our patient cohort. The most frequent cytogenetic abnormality found in our study was the t(15;17), followed by the t(8;21). Striking differences in the genetic abnormalities and French-American-British subtypes were found among infants, children, and adolescents. Of 124 cases, 15 (12.1%) met the criteria of the MK definition, and 12 of the 15 MKs (80%) were complex karyotypes. Of 124 cases, 27 (21.8%) had cytogenetic abnormalities sufficient to be diagnosed as AML with myelodyspastic sydrome-related features. As expected, patients with the t(15;17) had the most favorable outcomes, whereas patients with 11q23 rearrangements and monosomy 7 had the worst outcomes. These data expand our knowledge by providing novel insights into the cytogenetic features and their correlations with clinical characteristics and outcomes in childhood and adolescent AML.

Liposomal amphotericin B and surgery as successful therapy for pulmonary Lichtheimia corymbifera zygomycosis in a pediatric patient with acute promyelocytic leukemia on antifungal prophylaxis with posaconazole

Pulmonary zygomycosis, also referred to as mucormycosis, is a fungal infection of lungs caused by fungi of the order Mucorales in the class of Zygomycetes. It is usually associated with high morbidity and mortality. Here, we report the case of a 14-year-old girl with pediatric acute promyelocytic leukemia (APL) on antifungal prophylaxis with posaconazole, who developed pulmonary Lichtheimia corymbifera (formerly Absidia corymbifera) zygomycosis. She was successfully treated by means of liposomal amphotericin B (L-AmB) and surgery. To our knowledge, this is the first published report on pediatric APL and pulmonary zygomycosis in the English language literature. At present, the patient is in complete remission of her APL and without any signs of recurrence of zygomycosis. This report suggests that efficient diagnostics, increased physician awareness, and reliance on adjunctive surgical therapy can result in a favorable outcome of pulmonary zygomycosis in immunocompromised children with hematological malignancies.

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.

Acute promyelocytic leukemia with complex translocation t(5;17;15)(q35;q21;q22): case report and review of the literature

The t(15;17)(q22;q21), resulting in PML-RARA fusion gene, is a characteristic chromosomal translocation in acute promyelocytic leukemia (APL). We report a pediatric APL case with a 3-way translocation: t(5;17;15)(q35;q21;q22). Complete blood cell counts of a 12-year-old girl, of pale appearance, showed pancytopenia with increased blasts. Morphology and immunophenotype of the leukemic cells were compatible with APL. Karyotype analysis showed t(5;17;15)(q35;q21;q22) and add(7)(q32). We detected the PML-RARA fusion gene by both reverse transcriptase-polymerase chain reaction and fluorescent in situ hybridization analysis. The patient underwent successful treatment with cytarabine with all-trans retinoic acid and anthracycline-based therapy.

Long-term remission after first-line single-agent treatment with arsenic trioxide of relapsed acute promyelocytic leukemia in an 8-year-old boy

Arsenic trioxide (ATO) has been proven to be highly effective in adults with newly diagnosed or relapsed acute promyelocytic leukemia (APL). Only very limited data are published on the use of ATO as a single agent for first-line therapy of relapsed APL. The authors present a case of a 8-year-old boy with a bone marrow relapse of APL 7 years after first diagnosis, who achieved durable molecular remission with ATO as single agent: induction therapy for 12 weeks, consolidation for 4 weeks, then 6 cycles of 10 days over a period of 6 months. In total, 140 doses of ATO (0.15 mg/kg/day) were given (21 mg/kg). Consecutive promyelocytic leukemia-retinoic acid receptor α (PML-RARα) RT-PCR analyses were negative with a follow-up of 48 months. Acute or late side effects of arsenic were not observed. At present, the boy is in complete remission 4 years after the diagnosis of the relapse.

Regulation of S100A10 by the PML-RAR-α oncoprotein

Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia that results from the expression of the promyelocytic leukemia–retinoic acid receptor α (PML-RAR-α) oncoprotein. It is characterized by severe hemorrhagic complications due in part to excessive fibrinolysis, resulting from the excessive generation of the fibrinolytic enzyme, plasmin, at the cell surface of the PML cells. The treatment of patients with all-trans retinoic acid (ATRA) effectively ameliorates the disease by promoting the destruction of the PML-RAR-α oncoprotein. In the present study we show for the first time that the plasminogen receptor, S100A10, is present on the extracellular surface of APL cells and is rapidly down-regulated in response to all-trans retinoic acid. The loss of S100A10 is concomitant with a loss in fibrinolytic activity. Furthermore, the induced expression of the PML-RAR-α oncoprotein increased the expression of cell surface S100A10 and also caused a dramatic increase in fibrinolytic activity. Depletion of S100A10 by RNA interference effectively blocked the enhanced fibrinolytic activity observed after induction of the PML-RAR-α oncoprotein. These experiments show that S100A10 plays a crucial role in the generation of plasmin leading to fibrinolysis, thus providing a link to the clinical hemorrhagic phenotype of APL.