Acute promyelocytic leukemia in children and adolescents

Tocotrienols-enriched Self-nanoemulsifying Drug Delivery System Enhances the Antileukemic Activity of All-trans Retinoic Acid but not Electrocardiogram Alterations Evoked by Its Combination with Arsenic Trioxide

All-trans retinoic acid and arsenic trioxide are the leading choices for the treatment of acute promyelocytic leukemia. Notwithstanding the impressive differentiative properties of all-trans retinoic acid and the apoptotic properties of arsenic trioxide, some problems still occur in acute promyelocytic leukemia treatment. These problems are due to patients' relapses, mainly related to changes in the ligand-binding domain of RARα (retinoic acid receptor α) and the cardiotoxic effects caused by arsenic trioxide. We previously developed a self-nanoemulsifying drug delivery system enriched with tocotrienols to deliver all-trans retinoic acid (SNEDDS-TRF-ATRA). Herein, we have evaluated if tocotrienols can help revert ATRA resistance in an APL cell line (NB4-R2 compared to sensitive NB4 cells) and mitigate the cardiotoxic effects of arsenic trioxide in a murine model. SNEDDS-TRF-ATRA enhanced all-trans retinoic acid cytotoxicity in NB4-R2 (resistant) cells but not in NB4 (sensitive) cells. Moreover, SNEDDS-TRF-ATRA did not significantly change the differentiative properties of all-trans retinoic acid in both NB4 and NB4-R2 cells. Combined administration of SNEDDS-TRF-ATRA and arsenic trioxide could revert QTc interval prolongation caused by ATO but evoked other electrocardiogram alterations in mice, such as T wave flattening. Therefore, SNEDDS-TRF-ATRA may enhance the antileukemic properties of all-trans retinoic acid but may influence ECG changes caused by arsenic trioxide administration. SNEDDS-TRF-ATRA presents cytotoxicity in resistant APL cells (NB4-R2). Combined administration of ATO and SNEDDS-TRF-ATRA in mice prevented the prolongation of the QTc interval caused by ATO but evoked ECG abnormalities such as T wave flattening.

Early mortality continues to be a barrier to excellent survival in childhood acute promyelocytic leukemia: a retrospective study of 62 patients spanning 17 years

Data on childhood acute promyelocytic leukemia (APL) from low-and middle-income countries is limited. Early mortality is a concern and often not highlighted in clinical trials. The retrospective study was conducted on patients (≤12 years) with APL from 2003 to 2021 at a single center in India. Patients were treated with all-trans-retinoic acid (ATRA) and chemotherapy. Induction and three courses of consolidation were followed by maintenance for 2 years. In 2015, the protocol was updated with following modifications: (a) obtaining diagnostic cerebrospinal fluid at end-of-induction rather than at diagnosis, (b) administering intrathecal cytarabine regardless of risk-category, (c) risk-stratified administration of chemotherapy, and (d) inclusion of ATRA in all the cycles of consolidation. Sixty-two patients were diagnosed over the 17 years. The median age was 8 years (range: 0.9-12). Half had high-risk disease. Differentiation syndrome was observed in 32%, none being fatal. Eighteen (29%) patients died due to hemorrhage (83%) or septicemia (17%). Thirteen (21%) had early mortality (≤15 days), all due to hemorrhage. A platelet count <20 × 10⁹/L predicted early mortality (odds ratio: 4.5; 95% CI: 0.9-22, p = 0.06). Treatment abandonment reduced from 23.5% during 2003-2015 to nil during 2015-2021 (p = 0.006). Three (8%) patients relapsed. The 4-year OS of all patients and the patients who survived >15 days was 70.1% and 89.6%, respectively. The 4-year EFS, including abandonment and early mortality, before and following updated protocol, was 61.4% and 65.5%, respectively (p = 0.77). Early mortality continues to be a barrier to an otherwise excellent survival in childhood APL. A significant reduction in treatment abandonment in recent years is gratifying.

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.

All-trans retinoic acid in anticancer therapy: how nanotechnology can enhance its efficacy and resolve its drawbacks

Introduction: All-trans retinoic acid (ATRA, tretinoin) is the main drug used in the treatment of acute promyelocytic leukemia (APL). Despite its impressive activity against APL, the same could not be clinically observed in other types of cancer. Nanotechnology can be a tool to enhance ATRA anticancer efficacy and resolve its drawbacks in APL as well as in other malignancies.Areas covered: This review covers ATRA use in APL and non-APL cancers, the problems that were found in ATRA therapy and how nanoencapsulation can aid to circumvent them. Pre-clinical results obtained with nanoencapsulated ATRA are shown as well as the two ATRA products based on nanotechnology that were clinically tested: ATRA-IV® and Apealea®.Expert opinion: ATRA presents interesting properties to be used in anticancer therapy with a notorious differentiation and antimetastatic activity. Bioavailability and resistance limitations impair the use of ATRA in non-APL cancers. Nanotechnology can circumvent these issues and provide tools to enhance its anticancer activities, such as co-loading of multiple drug and active targeting to tumor site.

Prevalence and outcomes of thrombotic and hemorrhagic complications in pediatric acute promyelocytic leukemia in a tertiary Brazilian center

INTRODUCTION

Little attention is given to thrombosis associated with pediatric acute promyelocytic leukemia (APL). This study describes the thrombotic and hemorrhagic manifestations of APL in pediatric patients and evaluates their hemostasis, based on coagulation tests.

METHODS

Inclusion criteria were age 0-18 years and APL diagnosis between April 2005 and November 2017. Patients who had received blood transfusion prior to coagulation tests were excluded. Baseline coagulation tests, hematologic counts, and hemorrhagic/thrombotic manifestations were evaluated.

RESULTS

Median age was 10.7 years (1-15 years). The initial coagulation tests revealed a median Hgb of 8.3 g/dL (4.7-12.9 g/dL), median leucocyte count of 10.9 × 10⁹/L (1.1-95.8 × 10⁹/L), median platelet count of 31.8 × 10⁹/L (2.0-109.0 × 10⁹/L), median activated partial thromboplastin time (aPTT) of 31.7 s (23.0-50.4 s), median aPTT ratio of 1.0 (0.78-1.6), median thromboplastin time (PT) of 17.5 s (13.8-27.7 s), median PT activity of 62% (25-95 %), and median fibrinogen of 157.7 mg/dL (60.0-281.0 mg/dL). Three patients (13%) had thrombosis. At diagnosis, 21 patients (91.3%) had bruising, one patient (4.3%) had splenic vein and artery thrombosis and one patient (4.3%) presented without thrombohemorrhagic manifestations. During treatment, two patients (8.6%) had thrombosis.

CONCLUSION

Knowledge of thrombosis in pediatric APL is important to determine its risk factors and the best way to treat and prevent this complication.

Novel self-nanoemulsifying drug-delivery system enhances antileukemic properties of all-trans retinoic acid

Aim: All- trans retinoic acid (ATRA) shows erratic oral bioavailability when administered orally against leukemia, which can be solved through its incorporation in self-nanoemulsifying drug-delivery systems (SEDDS). The SEDDS developed contained a hydrophobic ion pair between benzathine (BZT) and ATRA and was enriched with tocotrienols by the input of a palm oil tocotrienol rich fraction (TRF) in its composition. Results: SEDDS-TRF-ATRA-BZT allowed the formation of emulsions with nanometric size that retained ATRA within their core after dispersion. Pharmacokinetic parameters after oral administration of SEDDS-TRF-ATRA-BZT in mice were improved compared with what was seen for an ATRA solution. Moreover, SEDDS-TRF-ATRA-BZT had improved activity against HL-60 cells compared with SEDDS without TRF. Conclusion: SEDDS-TRF-ATRA-BZT is a promising therapeutic choice over ATRA conventional medicine.

The Survival of Patients with t(15;17)(q22;q12) Positive Acute Promyelocytic Leukemia: A Study in North-East of Iran

Background & Objective

Acute promyelocytic leukemia (APL) with t(15;17)(q22;q12) is a relatively common subtype of acute myeloid leukemia (AML). Here, our objective was to ascertain the survival of patients with this leukemia in north-east of Iran.

Methods

Survival rates of 42 APL patients with t(15;17)(q22;q12) were assessed. Clinical information was obtained from archived medical records. Statistical analysis was performed by SPSS 18 software using log-ranked test and Kaplan Maier survival analysis.

Results

Females and males comprised 49% and 51%, respectively. The mean age at diagnosis was 34.3 ± 14.1 years old. During the study period, 17 demises occurred in males, while this number was 7 in females. The mean survival of patients (month) was 23.22 ± 3.57 (95% CI: 16.21 ± 30.2). The five-year survival rate obtained 30%. Regarding demographic and clinical features, the highest rates of 5-year survival were recorded in patients with 20-35 years old (47.6%), males (51%), white blood cell count <10 × 10 9 /l (48%), and platelet count >140 × 10 9 /l (100%).

Conclusion

Younger age, lower WBC count and higher platelet count were significantly associated with longer survival in AML patients with t(15;17)(q22; q12).

Treatment Outcome and the Genetic Characteristics of Acute Promyelocytic Leukemia in Children in Poland From 2005 to 2018

Background: The aim of the study was to analyze the treatment outcome and genetic characteristics of acute promyelocytic leukemia (APL) in children in Poland from 2005 to 2018. Methods: All 41 patients diagnosed with APL in Poland during the analysis period were eligible for the study. In period I (2005-2015), 33 patients were treated with chemotherapy and all-trans retinoic acid (ATRA), and in period II (2015-2018), 3 patients (high risk) received induction chemotherapy with ATRA and arsenic trioxide (ATO), and 5 patients (standard risk) received ATRA and ATO without chemotherapy. Results: Probability of 5-years overall survival (OS), event-free survival (EFS), and relapse-free survival (RFS) was 0.819 ± 0.069, 0.831 ± 0.063, and 0.961 ± 0.037, respectively, in the whole cohort. Four (11%) early deaths were observed. One patient died of severe infection in the course of disease progression. Relapse occurred in one patient, who died finally because of disease progression. All events occurred in the patients from period I. Variant APL was identified in one patient (successfully treated with chemotherapy with ATRA) and complex translocation in one patient (the only patient with relapse). Additional chromosomal aberrations were found in 26% of patients and FLT3-ITD mutation was detected in 44% of patients; none of those changes influenced clinical outcome. Conclusion: Treatment outcome in the analyzed group is similar to the results reported by other study groups. The main cause of death was coagulation disorders in the early stage of disease. Early, accurate diagnosis followed by specific treatment enables the reduction in the number of early deaths.

Acute Promyelocytic Leukemia in Children: A Single Centre Experience from Turkey

Background and objectives

Acute promyelocytic leukemia (APL), is a distinct subtype of acute myeloid leukemia (AML) characterized by a tendency to hemorrhage and excellent response to all-trans retinoic acid (ATRA). In this retrospective study, we aimed to determine the incidence, clinical symptoms, toxicities, and outcome of children with APL in our center.

Methods

We retrospectively reviewed the medical records of children (age < 18 years) diagnosed with APL in our pediatric hematology department between January 2006-December 2016.

Results

Pediatric APL represents 20.5% of AML cases in this cohort. Most of the cases presented as classical M3, albeit hypogranular variant was described in 12% of the cohort. Patients with hypogranular variant APL were differed from classical APL by co-expression of CD2 and CD34. About ¾ of APL patients had hemorrhagic findings at admission or the induction treatment. Severe bleeding manifested as intracranial hemorrhage was present in three patients and intracranial arterial thrombosis was present in one. Six patients showed side effects of ATRA such as pseudotumor cerebri, differentiation syndrome resulting in dilated cardiomyopathy, and pulmonary infiltrates. Five-year overall survival (OS) and early death rate were found to be 82.5% and 12% respectively.

Conclusions

A high frequency (20.5%) of APL was noted among children with AML in this single-center study. The overall mortality rate was 17.5%. Since the induction death rate was 12% and life-threatening bleeding was the primary problem, awareness and urgent treatment are critical factors to reduce early losses.

A Rare Case of Relapsed Pediatric Acute Promyelocytic Leukemia with Skin Involvement by Myeloid Sarcoma

BACKGROUND Acute promyelocytic leukemia (APL) is a very rare leukemia in children. Extramedullary involvement by APL has been reported in between 3-5% of cases, mainly associated with cases of relapse. A rare case of relapse of APL in a 9-year-old child is presented with skin involvement with myeloid sarcoma. CASE REPORT A 9-year-old male child was admitted to the Oncology Service of the hospital complaining of fever, progressive fatigue, oral petechiae with severe bleeding in the oral cavity. Bone marrow examination showed some promyelocytes. Flow cytometry showed 86% immature myeloid cells with the t(15;17) translocation, and molecular analysis showed expression of the PML/RARa fusion protein, which confirmed the diagnosis of APL. The patient completed a course of daunorubicin, cytarabine, and AII trans-retinoic acid (ATRA) with complete remission. After six months, the patient was re-admitted to hospital with a violaceous lesion on the scalp, with relapse of APL. Histological and immunohistochemistry of the lesion involving the skin of the scalp showed a myeloid sarcoma invading the dermis. CONCLUSIONS Myeloid sarcoma, also called granulocytic sarcoma, is an extramedullary tumor of immature myeloid cells, which very rarely presents in children with APL. The mechanisms that lead to myeloid sarcoma in children with APL and the possible association with ATRA therapy remain to be investigated.

Arsenic trioxide induces Noxa-dependent apoptosis in rhabdomyosarcoma cells and synergizes with antimicrotubule drugs

The prognosis of metastatic or relapsed rhabdomyosarcoma (RMS) is poor, highlighting the need of new treatment options. In the present study, we evaluated the in vitro efficacy of arsenic trioxide (ATO) in RMS, a FDA-approved drug used in pediatric leukemia. Here, we report that ATO exerts antitumor activity against RMS cells both as single agent and in combination with microtubule-targeting drugs. Monotherapy with ATO reduces cell viability, triggers apoptosis and suppresses clonogenic survival of RMS cells, at least in part, by transcriptional induction of the proapoptotic BH3-only protein Noxa. siRNA-mediated knockdown of Noxa significantly rescues ATO-mediated cell death, demonstrating that Noxa is required for cell death. Also, ATO suppresses endogenous Hedgehog (Hh) signaling, as it significantly reduces Gli1 transcriptional activity and expression levels of several Hh target genes. Furthermore, we identify synergistic induction of apoptosis by ATO together with several antimicrotubule agents including vincristine (VCR), vinblastine and eribulin. The addition of the broad-range caspase inhibitor zVAD.fmk or overexpression of the antiapoptotic protein Bcl-2 significantly reduce ATO/VCR-induced cell death, indicating that the ATO/VCR combination triggers caspase-dependent apoptosis via the mitochondrial pathway. In summary, ATO exerts antitumor activity against RMS, especially in combination with antimicrotubule drugs. These findings have important implications for the development of novel therapeutic strategies for RMS.

Genetic network profiles associated with established resistance to ionizing radiation in acute promyelocytic leukemia cells and their extracellular vesicles

Radiation-resistant acute promyelocytic leukemia (APL) cells present challenges to treatment, and the acquisition of resistance to ionizing radiation (IR) is a matter of clinical concern. However, little information is available on the behavior of radio-resistant APL in terms of gene expression profiles and intercellular communication. In this study, cDNA microarray and RT-PCR were used to analyze the intracellular genetic network and extracellular vesicles (EVs), respectively, in the established radio-resistant HL60 (Res-HL60) cell line. Significant changes in the expression of 7,309 known mRNAs were observed in Res-HL60 relative to control. In addition, 7 mRNAs were determined as targets because significant changes in the expression were observed using Ingenuity analysis software, confirming the quantitative RT-PCR. However, EVs from Res-HL60 cells did not include these target molecules. These results suggest that radio-resistant APL is regulated by the expression and suppression of specific molecules, and these molecules are not transferred between cells by EVs.