Management of acute promyelocytic leukemia: recommendations from an expert panel on behalf of the European LeukemiaNet. Blood. 2009;113:1875-1891. [PMID: 18812465 DOI: 10.1182/blood-2008-04-150250]

History of Acute Promyelocytic Leukemia

In this article, we discuss the history of acute promyelocytic leukemia (APL) from the pre-therapeutic era, which began after its recognition by Hillestad in 1947 as a nosological entity, to the present day. It is a paradigmatic history that has transformed the “most malignant leukemia form” into the most curable one. The identification of a balanced reciprocal translocation between chromosomes 15 and 17, resulting in fusion between the promyelocytic leukemia gene and the retinoic acid receptor alpha, has been crucial in understanding the mechanisms of leukemogenesis, and responsible for the peculiar response to targeted therapy with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). We review the milestones that marked successive therapeutic advances, beginning with the introduction of the first successful chemotherapy in the early 1970s, followed by a subsequent incorporation of ATRA and ATO in the late 1980s and early 1990s which have revolutionized the treatment of this disease. Over the past two decades, treatment optimization has relied on the combination of ATRA, ATO, and chemotherapy according to risk-adapted approaches, which together with improvements in supportive therapy have paved the way for cure for most patients with APL.

STMN1 is highly expressed and contributes to clonogenicity in acute promyelocytic leukemia cells

Stathmin 1 (STMN1) is a microtubule-destabilizing protein highly expressed in hematological malignancies and involved in proliferation and differentiation. Although a previous study found that the PML-RARα fusion protein, which contributes to the pathophysiology of acute promyelocytic leukemia (APL), positively regulates STMN1 at the transcription and protein activity levels, little is known about the role of STMN1 in APL. In this study, we aimed to investigate the STMN1 expression levels and their associations with laboratory, clinical, and genomic data in APL patients. We also assessed the dynamics of STMN1 expression during myeloid cell differentiation and cell cycle progression, and the cellular effects of STMN1 silencing and pharmacological effects of microtubule-stabilizing drugs on APL cells. We found that STMN1 transcripts were significantly increased in samples from APL patients compared with those of healthy donors (all p < 0.05). However, this had no effect on clinical outcomes. STMN1 expression was associated with proliferation- and metabolism-related gene signatures in APL. Our data confirmed that STMN1 was highly expressed in early hematopoietic progenitors and reduced during cell differentiation, including the ATRA-induced granulocytic differentiation model. STMN1 phosphorylation was predominant in a pool of mitosis-enriched APL cells. In NB4 and NB4-R2 cells, STMN1 knockdown decreased autonomous cell growth (all p < 0.05) but did not impact ATRA-induced apoptosis and differentiation. Finally, treatment with paclitaxel (as a single agent or combined with ATRA) induced microtubule stabilization, resulting in mitotic catastrophe with repercussions for cell viability, even in ATRA-resistant APL cells. This study provides new insights into the STMN1 functions and microtubule dynamics in APL.

Neurologic complications of acute myeloid leukemia. Diagnostic approach and therapeutic modalities

Acute myeloid leukemia (AML) comprises a heterogeneous group of aggressive blood malignancies that arise from clonal expansion of malignant hematopoietic precursor cells in the bone marrow. Neurologic manifestations of these malignancies are manifolds. AML is the most common form of acute leukemia in adults and this review describes the neurologic complications in this age group. Neurologic symptoms and signs may develop in AML either from a direct neoplastic involvement of the central or the peripheral nervous system or as an indirect effect of the disease process. Direct involvement of the nervous system includes invasion of the central or the peripheral nervous system (parenchymal and leptomeningeal dissemination, myeloid sarcoma, neuroleukemiosis). Thrombotic and hemorrhagic events are common manifestations of indirect involvement of the nervous system and they are the outcome of hyperleukocytosis, thrombocytopenia and coagulopathy. Many neurologic complications are iatrogenic and include diverse categories such as lumbar puncture and intrathecal or systemic chemotherapy and targeted therapies, radiotherapy and allogeneic stem cell transplantation. Most neurologic manifestations require urgent treatment and confer a poor prognosis. This review describes the neurologic complications of acute myeloid malignancies in the era of contemporary treatment. Those manifestations require expert consideration of their origin as they are being identified with increasing frequency as patients survive longer.

Assessment of Arsenic Trioxide and All-trans Retinoic Acid for the Treatment of Pediatric Acute Promyelocytic Leukemia: A Report From the Children's Oncology Group AAML1331 Trial

Importance

All-trans retinoic acid (ATRA) and arsenic trioxide therapy without the use of maintenance therapy has been found to be beneficial for the treatment of adults with standard-risk acute promyelocytic leukemia (APL). However, it is unclear whether similar regimens are safe and beneficial for the treatment of high-risk APL or pediatric patients with standard-risk APL.

Objective

To assess whether treatment with an ATRA and arsenic trioxide-based regimen is safe and allows for the elimination or substantial reduction of chemotherapy use among pediatric patients with standard-risk or high-risk APL, respectively.

Design, Setting, and Participants

The Children's Oncology Group AAML1331 study is a nonrandomized, noninferiority trial that examined survival outcomes among 154 pediatric patients with APL compared with a historical control group of patients with APL from the AAML0631 study. Patients aged 1 to 21 years were enrolled at 85 pediatric oncology centers (members of the Children's Oncology Group) in Australia, Canada, and the US from June 29, 2015, to May 7, 2019, with follow-up until October 31, 2020. All patients had newly diagnosed APL and were stratified into standard-risk APL (white blood cell count <10 000/μL) and high-risk APL (white blood cell count ≥10 000/μL) cohorts.

Interventions

All patients received ATRA and arsenic trioxide continuously during induction therapy and intermittently during 4 consolidation cycles. Patients with high-risk APL received 4 doses of idarubicin during induction therapy only. The duration of therapy was approximately 9 months, and no maintenance therapy was administered.

Main Outcomes and Measures

Event-free survival (EFS) at 2 years after diagnosis.

Results

Among 154 patients (median age, 14.4 years [range, 1.1-21.7 years]; 81 male participants [52.6%]) included in the analysis, 98 patients (63.6%) had standard-risk APL, and 56 patients (36.4%) had high-risk APL. The median follow-up duration was 24.7 months (range, 0-49.5 months) for patients with standard-risk APL and 22.8 months (range, 0-47.7 months) for patients with high-risk APL. Patients with standard-risk APL had a 2-year EFS rate of 98.0% and an overall survival rate of 99.0%; adverse events included 1 early death during induction therapy and 1 relapse. Patients with high-risk APL had a 2-year EFS rate of 96.4% and an overall survival rate of 100%; adverse events included 2 relapses and 0 deaths. These outcomes met predefined noninferiority criteria (noninferiority margin of 10% among those with standard-risk APL and 14.5% among those with high-risk APL).

Conclusions and Relevance

In this nonrandomized, noninferiority trial, pediatric patients with standard-risk APL who received treatment with a chemotherapy-free ATRA and arsenic trioxide regimen experienced positive outcomes. Patients with high-risk APL also had positive outcomes when treated with a novel ATRA and arsenic trioxide-based regimen that included 4 doses of idarubicin during induction therapy only and no maintenance therapy. The 2-year EFS estimates were noninferior to the historical comparator group, and advantages of the regimen included shorter treatment duration, lower exposure to anthracycline and intrathecal chemotherapy, and fewer days hospitalized.

Trial Registration

ClinicalTrials.gov Identifier: NCT02339740.

Practice Patterns and Real-Life Outcomes for Patients with Acute Promyelocytic Leukemia in the United States

14% of newly diagnosed APL patients in the Vizient Clinical Data Base died during initial admission or were discharged to hospice.

Adverse outcomes were lower with guideline-concordant treatment, low-risk disease, higher hospital AML volume, and younger age.

Acute promyelocytic leukemia (APL) is associated with a favorable long-term prognosis if appropriate treatment is initiated promptly. Outcomes in clinical trials and population-based registries vary; potential explanations include a delay in treatment and lower adherence to guideline-recommended therapy in real-world practice. We used the Vizient Clinical Data Base to describe demographic characteristics, baseline clinical characteristics, and treatment patterns in patients newly diagnosed with APL during the study period of April 2017 to March 2020. Baseline white blood cell count was used to assign risk status and assess treatment concordance with National Comprehensive Cancer Network guidelines. Logistic regression models examined adjusted associations between patient, hospital, disease characteristics, and adverse outcomes (in-hospital death or discharge to hospice). Among 1464 patients with APL, 205 (14.0%) experienced an adverse outcome. A substantial subset (20.6%) of patients did not receive guideline-concordant regimens. Odds of adverse outcomes increased with failure to receive guideline-concordant treatment (odds ratio [OR], 2.31; 95% confidence interval [CI], 1.43-3.75; P = .001), high-risk disease (OR, 2.48; 95% CI, 1.53-4.00; P < .001), and increasing age (≥60 years: OR, 11.13; 95% CI, 4.55-27.22; P < .001). Higher hospital acute myeloid leukemia (AML) patient volume was associated with lower odds of adverse outcome (OR, 0.44; 95% CI, 0.20-0.99 [for ≤50 vs >200 AML patients per year]; P = .046). In conclusion, in this large database analysis, 14.0% of patients newly diagnosed with APL died or were discharged to hospice. A substantial proportion of patients did not receive guideline-concordant therapy, potentially contributing to adverse outcomes.

Disruption of a GATA2-TAL1-ERG regulatory circuit promotes erythroid transition in healthy and leukemic stem cells

Changes in gene regulation and expression govern orderly transitions from hematopoietic stem cells to terminally differentiated blood cell types. These transitions are disrupted during leukemic transformation, but knowledge of the gene regulatory changes underpinning this process is elusive. We hypothesized that identifying core gene regulatory networks in healthy hematopoietic and leukemic cells could provide insights into network alterations that perturb cell state transitions. A heptad of transcription factors (LYL1, TAL1, LMO2, FLI1, ERG, GATA2, and RUNX1) bind key hematopoietic genes in human CD34+ hematopoietic stem and progenitor cells (HSPCs) and have prognostic significance in acute myeloid leukemia (AML). These factors also form a densely interconnected circuit by binding combinatorially at their own, and each other's, regulatory elements. However, their mutual regulation during normal hematopoiesis and in AML cells, and how perturbation of their expression levels influences cell fate decisions remains unclear. In this study, we integrated bulk and single-cell data and found that the fully connected heptad circuit identified in healthy HSPCs persists, with only minor alterations in AML, and that chromatin accessibility at key heptad regulatory elements was predictive of cell identity in both healthy progenitors and leukemic cells. The heptad factors GATA2, TAL1, and ERG formed an integrated subcircuit that regulates stem cell-to-erythroid transition in both healthy and leukemic cells. Components of this triad could be manipulated to facilitate erythroid transition providing a proof of concept that such regulatory circuits can be harnessed to promote specific cell-type transitions and overcome dysregulated hematopoiesis.

Acute Promyelocytic Leukemia: Update on Risk Stratification and Treatment Practices

Acute promyelocytic leukemia (APL) is a rare but highly curable form of acute myeloid leukemia (AML) whose genetic hallmark is the balanced reciprocal translocation t(15;17)(q22;q12) which fuses the promyelocytic leukemia (PML) and retinoic acid receptor alpha (RARα) genes (Wang and Chen in Blood 111:2505-2515, 2008; Lallem and-Breitenbach et al. in J Exp Med 189:1043-1052, 1999). It is a rare disease and accounts for 5-10% of adult AML with an estimated incidence of 0.1/100,000 in Western countries (Sant et al. in Blood 116:3724-3734, 2010). In the United States, 600-800 new cases are diagnosed every year although the incidence appears increased in patients originating from Latin America (Douer in Best Pract Res Clin Haematol 16:357-367, 2003). Notably, the median age at diagnosis is approximately 40 years which is significantly lower than in AML where the median age is 68 years.

A practical strategy to subcutaneous administered in-situ gelling co-delivery system of arsenic and retinoic acid for the treatment of acute promyelocytic leukemia

Arsenic trioxide (ATO) combined with all trans retinoic acid (ATRA) is the first choice for the treatment of low and medium risk acute promyelocytic leukemia (APL). Clinical studies reported that the combination of ATO and ATRA could achieve a significant curative effect. However, the retinoic acid syndrome, serious drug resistance and the short half-life in vivo which lead to frequent and large dose administration limit the application of ATRA. In addition, the preparations of arsenic are conventional injections and tablets in clinic, which has poor patients' compliance caused by frequent long-term administration and serious side effects. In order to overcome the above limitations, a phospholipid phase separation gel (PPSG) loaded with ATO and ATRA was developed. ATO+ATRA-PPSG (AAP), as a biodegradable sustained-release delivery system, was the first achievement of co-delivery of hydrophilic ATO and lipophilic ATRA with high drug loading which is the main problem in the application of nano preparation. The prepared PPSG displayed high safety and biocompatibility. The drug in PPSG was released slowly and continuously in vivo and in vitro for up to 10 d, which could reduce the side effects caused by the fluctuation of blood drug concentration and solve the problem of the long treatment cycle and frequent administration. In vivo pharmacokinetics depicted that PPSG could improve the bioavailability, decrease the peak concentration, and prolong the t1/2 of ATO and ATRA. Particularly, AAP significantly inhibited the tumor volume, extended the survival period of tumor-bearing mice, and promoted the differentiation of APL cells into normal cells. Therefore, ATO+ATRA-PPSG not only could co-load hydrophilic ATO and lipophilic ATRA according to the clinical dosage, but also possessed the sustained-release and long-acting treatment effect which was expected to reduce administration time and ameliorate compliance of patients. Thus, it had great potential for clinical transformation and application.

Drug treatment options for acute promyelocytic leukemia

INTRODUCTION

Until the late 1980s, acute promyelocytic leukemia (APL) was the most rapidly fatal leukemia; however, nowadays, it is a curable disease with survival rates exceeding 90-95%. The improvement of APL outcome is mainly due to two agents, which target the typical translocation t(15;17) and its fusion transcript PML-RARα responsible for initiating and maintaining the disease: all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). The story of APL represents a pioneering model for the development of precision medicine and curative chemotherapy-free approaches for acute leukemia.

AREA COVERED

The authors examine the major advances in the treatment of patients with APL focusing on three different eras: 1) the pre-ATRA era; 2) the ATRA era; 3) the ATO era.

EXPERT OPINION

The combination of ATRA and ATO is effective and curative for the majority of APL patients. It has been approved for low/intermediate risk cases while an experimental trial with a minimal addition of chemotherapy for high-risk ones is ongoing. Disease relapse is infrequent and can be cured with ATRA-ATO rechallenging, with or without subsequent transplantation depending on the interval between complete remission and relapse. New therapeutic landscapes contemplate the use of an oral chemo-free ATRA-ATO combination, implementing treatment as outpatient care, thus increasing quality of life and decreasing medical costs.

Arsenic trioxide in pediatric cancer - a case series and review of literature

Arsenic trioxide (ATO) has become an established component of treatment protocols for acute promyelocytic leukemia (APL) with excellent efficacy and no relevant sustained toxicity. Part of its action has been attributed to the inhibition of Hedgehog signaling (Hh) which enables a possible therapeutic approach as many pediatric tumor entities have been associated with increased Hh activity. We retrospectively analyzed 31 patients with refractory and relapsed pediatric cancer who were treated with ATO at the University Children's Hospital of Tuebingen. Additionally a literature review on the clinical and preclinical use of ATO in pediatric cancer treatment was performed.ATO alone as well as combinations with other drugs have proven effective in vitro and in mouse models of various pediatric malignancies. However, only few data on the clinical use of ATO in pediatric patients besides APL exist. In our patient sample, ATO was overall well tolerated in the treatment of various pediatric cancers, even in combination with other cytostatic drugs. Due to distinct tumor entities, differently progressed disease stages and varying co-medication, no clear statement can be made regarding the efficacy of ATO treatment. However, patients with proven Hh activation in molecular tumor profiling surpassed all other patients, who received ATO in an experimental treatment setting, in terms of survival. As molecular profiling of tumors increases and enhanced Hh activity can be detected at an early stage, ATO might expand its clinical use to other pediatric malignancies beyond APL depending on further clinical studies.

Leukapheresis and Hyperleukocytosis, Past and Future

Hyperleukocytosis is a hematologic crisis caused by excessive proliferation of leukemic cells and has a relatively high early mortality due to a series of severe complications. Therefore, prompt and effective intervention is required. Leukapheresis performed using apheresis equipment to separate leukocytes from peripheral blood, at the same time returns autologous plasma, platelets and erythrocytes to the patient, is applied clinically for the treatment of hyperleukocytosis. Leukapheresis not only removes excessive leukocytes rapidly and corrects metabolic abnormalities but also alleviates the symptoms of leukostasis. In addition, the procedure of leukapheresis is generally well tolerated. Leukapheresis has become one of the most imperative adjuvant therapies to treat hyperleukocytosis, especially in the patient who was not inappropriate to cytoreduce with Ara-C or hydroxyurea. In this review, we present the background of leukapheresis development and highlight its clinical application in hyperleukocytic leukemia patients.

Early death in acute promyelocytic leukemia: Evidence from a rural cancer center

Background

Early death is still the characteristic feature of acute promyelocytic leukemia (APL) despite the advances in the treatment regimen. Analyzing the incidence of early death would prove beneficial as no much substantial information is available pertaining to the rural population. The present study analyzed the incidence of APL-associated early death, its clinical characteristics, and outcome among acute myeloid leukemia patients.

Methods

This retrospective study included patients catering to the rural areas of Vijayawada (Andhra Pradesh, India) from January 2013 to June 2017. Chi-square test, Fisher's exact test, independent sample median test, and Kaplan-Meier test for probability of survival were used.

Results

Of the 204 acute myeloid cases, 24% cases (median age = 30 years; range=8 to 68 years) were identified as APL. Early death rate was 34.6%, who expired within 30 days from diagnosis with 65% suffering high disease risk. The median time from admission to death was 2 days (range 0-18). Cause of early death was majorly due to hemorrhage (64%). Moreover, 47.1% of early death patients received no prior antileukemic treatment. The overall 5-year cumulative disease-free survival rate among patients with APL was 76% where high disease risk patients had the least disease-free survival (65%-75%), whereas intermediate and low-risk patients had >80% and 100% disease-free survival rate, respectively.

Conclusion

Early diagnosis and timely intervention might help to prevent early death as our findings clearly indicate poor awareness of disease and lack of early intervention among the rural population.

Advances in the management of coagulopathy in acute promyelocytic leukemia

Since the introduction of all-trans retinoic acid and, more recently, arsenic trioxide into the therapy of acute promyelocytic leukemia (APL), significant improvements in patient outcomes have been achieved, and this disease has become the most curable subtype of acute myeloid leukemia. However, while primary leukemia resistance has virtually disappeared, a sizable fraction of APL patients still die before or during induction therapy. Hemorrhagic death still remains the major problem during this early phase of treatment and, to a lesser extent, deaths due to infection, differentiation syndrome and other causes. Patients with APL typically present with a range of laboratory abnormalities consistent with the diagnosis of disseminated intravascular coagulation and hyperfibrinolysis. This APL-associated coagulopathy, as a result of a dysregulation of the hemostatic system due to the imbalance between procoagulant, anticoagulant and profibrinolytic mechanisms, may show a variety of clinical manifestations, ranging from minimal bleeding or localized thrombosis to lethal or life-threatening hemorrhages or thrombotic events that sometimes occur concomitantly. Hemorrhagic events are the most common cause of death associated with APL coagulopathy, but thrombosis, a less recognized and probably underestimated life-threatening manifestation of the thrombo-hemorrhagic syndrome, is also a non-negligible cause of morbidity and mortality in patients with APL. In this article, we aim to discuss recent advances in the knowledge of pathogenesis, predictors of thrombo-hemorrhagic events, management of coagulopathy associated with APL and the controversial issues that still persist.

Expression and prognostic relevance of long noncoding RNAs CRNDE and AOX2P in adult acute myeloid leukemia

INTRODUCTION

Several long noncoding RNAs (lncRNAs) have been demonstrated to play a critical role in the tumorigenesis of acute myeloid leukemia (AML), and altered expression of certain lncRNAs has been recognized as a potential prognostic marker in AML patients. Here, we sought to determine whether the expression of the lncRNA colorectal neoplasia differentially expressed (CRNDE) and aldehyde oxidase 2 pseudogene (AOX2P) is associated with clinicopathological features and clinical outcome of patients with AML.

METHODS

CRNDE and AOX2P expression levels were measured in diagnostic blood samples from 200 adult patients with de novo AML, along with 50 healthy control blood samples, using quantitative real-time polymerase chain reaction (qRT-PCR). The association of CRNDE and AOX2P expression with the clinicopathological characteristics and outcome of AML patients was analyzed.

RESULTS

Upregulated CRNDE expression was independently associated with lower complete remission (CR) rates in the whole cohort of AML (P < .001). AOX2P overexpression was identified as an independent adverse prognostic marker for CR in the CN-AML (P = .009) and non-t (15;17) AML (P < .001) subgroups. Patients with high CRNDE expression had a significantly shorter event-free survival (EFS, whole cohort of AML: P = .017; CN-AML: P = .001; non-t (15;17) AML: P = .006) and inferior overall survival (OS, whole cohort of AML: P = .002; t(15;17) AML: P = .001) than those with low CRNDE expression. EFS and OS did not differ significantly between patients with high AOX2P expression and those with low expression.

CONCLUSION

Aberrantly upregulated CRNDE expression and, to a lesser extent, AOX2P overexpression, are associated with poor prognosis in AML patients, suggesting that the determination of CRNDE and, perhaps, AOX2P, expression level at diagnosis provides valuable prognostic information, allows refinement of risk stratification, and helps clinical decision-making in AML.

Poly(ADP-Ribose) Polymerase Inhibitors for Arsenic Trioxide-Resistant Acute Promyelocytic Leukemia: Synergistic In Vitro Antitumor Effects with Hypomethylating Agents or High-Dose Vitamin C

Arsenic trioxide (ATO) is an anticancer agent used for the treatment ofacute promyelocytic leukemia (APL). However, 5%-10% of patients fail to respond or experience disease relapse. Based on poly(ADP-ribose) polymerase (PARP) 1 involvement in the processing of DNA demethylation, here we have tested the in vitro susceptibility of ATO-resistant clones (derived from the human APL cell line NB4) to PARP inhibitors (PARPi) in combination with hypomethylating agents (azacitidine and decitabine) or high-dose vitamin C (ascorbate), which induces 5-hydroxymethylcytosine (5hmC)-mediated DNA demethylation. ATO-sensitive and -resistant APL cell clones were generated and initially analyzed for their susceptibility to five clinically used PARPi (olaparib, niraparib, rucaparib, veliparib, and talazoparib). The obtained PARPi IC50 values were far below (olaparib and niraparib), within the range (talazoparib), or above (rucaparib and veliparib) the C max reported in patients, likely as a result of differences in the mechanisms of their cytotoxic activity. ATO-resistant APL cells were also susceptible to clinically relevant concentrations of azacitidine and decitabine and to high-dose ascorbate. Interestingly, the combination of these agents with olaparib, niraparib, or talazoparib resulted in synergistic antitumor activity. In combination with ascorbate, PARPi increased the ascorbate-mediated induction of 5hmC, which likely resulted in stalled DNA repair and cytotoxicity. Talazoparib was the most effective PARPi in synergizing with ascorbate, in accordance with its marked ability to trap PARP1 at damaged DNA. These findings suggest that ATO and PARPi have nonoverlapping resistance mechanisms and support further investigation on PARPi combination with hypomethylating agents or high-dose ascorbate for relapsed/ATO-refractory APL, especially in frail patients. SIGNIFICANCE STATEMENT: This study found that poly(ADP-ribose) inhibitors (PARPi) show activity as single agents against human acute promyelocytic leukemia cells resistant to arsenic trioxide at clinically relevant concentrations. Furthermore, PARPi enhance the in vitro efficacy of azacitidine, decitabine, and high-dose vitamin C, all agents that alter DNA methylation. In combination with vitamin C, PARPi increase the levels of 5-hydroxymethylcytosine, likely as a result of altered processing of the oxidized intermediates associated with DNA demethylation.

Acute Promyelocytic Leukemia: A Long-Term Retrospective Study in Mexico

Background

The present retrospective study reviewed acute promyelocytic leukemia (APL) cases recorded in Mexico between January 2007 and January 2017. The primary objective of the study was to evaluate overall survival (OS) in Mexican patients with APL. Secondary objective was to evaluate the impact of induction treatment with different anthracyclines on OS, event-free survival (EFS) and complications in this patient population.

Methods

The medical charts of patients referred to medical institutions in Mexico from January 2007 through January 2017 for the treatment of suspected APL were reviewed retrospectively. Patients aged 15 - 75 years, in whom the diagnosis of APL was confirmed, who had an Eastern Cooperative Group performance status of 0 - 2, and who were eligible for combined treatment with intensive chemotherapy and all-trans retinoic acid (ATRA), were included in the study. Study participants received induction and consolidation treatment with ATRA plus either daunorubicin or idarubicin, followed by 2 years of single-agent ATRA as maintenance therapy. Patients who were unable to pay for ATRA treatment received anthracycline-based induction and consolidation, with methotrexate plus mercaptopurine as maintenance therapy.

Results

A total of 360 patients from 21 public and private hospitals were included in the study. The median age of the population was 37 years, and 51% were male. Of the 360 patients, 205 (57%) vs. 155 (43%) received daunorubicin vs. idarubicin as induction treatment for APL. ATRA was administered to 201 (98%) patients in the daunorubicin group vs. 138 (89%) in the idarubicin group (P = 0.001), and was initiated at diagnosis in 92% vs. 73% of recipients, respectively (P = 0.0001). At 150 months, OS and EFS for the entire population were 84% and 79%, respectively. Both OS (90% vs. 76%, P = 0.003) and EFS (85% vs. 72%, P = 0.001) were significantly prolonged in daunorubicin vs. idarubicin recipients. Rates of complications were similar in the two groups.

Conclusions

As arsenic trioxide (ATO) is not currently available in Mexico, anthracycline plus ATRA is the mainstay of treatment for APL here. Our results confirm the efficacy of this strategy, with high OS and EFS rates being observed 12.5 years after diagnosis.

Novel Mechanistic Insights into the Anti-cancer Mode of Arsenic Trioxide

Arsenic, a naturally-occurring toxic element, and a traditionally-used drug, has received a great deal of attention worldwide due to its curative anti-cancer properties in patients with acute promyelocytic leukemia. Among the arsenicals, arsenic trioxide has been most widely used as an anti-cancer drug. Recent advances in cancer therapeutics have led to a paradigm shift away from traditional cytotoxic drugs towards the targeting of proteins closely associated with driving the cancer phenotype. Due to the diverse anti-cancer effects of ATO on different types of malignancies, numerous studies have made efforts to uncover the mechanisms of ATO-induced tumor suppression. From in vitro cellular models to studies in clinical settings, ATO has been extensively studied. The outcomes of these studies have opened doors to establishing improved molecular-targeted therapies for cancer treatment. The efficacy of ATO has been augmented by combination with other drugs. In this review, we discuss recent arsenic-based cancer therapies and summarize the novel underlying molecular mechanisms of the anti-cancer effects of ATO.

Pediatric Fibrinogen PART II-Overview of Indications for Fibrinogen Use in Critically Ill Children

Bleeding is frequently seen in critically ill children and is associated with increased morbidity and mortality. Fibrinogen is an essential coagulation factor for hemostasis and hypofibrinogenemia is an important risk factor for bleeding in pediatric and adult settings. Cryoprecipitate and fibrinogen concentrate are often given to critically ill children to prevent bleeding and improve fibrinogen levels, especially in the setting of surgery, trauma, leukemia, disseminated intravascular coagulopathy, and liver failure. The theoretical benefit of fibrinogen supplementation to treat hypofibrinogenemia appears obvious, yet the evidence to support fibrinogen supplementation in children is sparce and clinical indications are poorly defined. In addition, it is unknown what the optimal fibrinogen replacement product is in children and neonates or what the targets of treatment should be. As a result, there is considerable variability in practice. In this article we will review the current pediatric and applicable adult literature with regard to the use of fibrinogen replacement in different pediatric critical care contexts. We will discuss the clinical indications for fibrinogen supplementation in critically ill children and the evidence to support their use. We summarize by highlighting current knowledge gaps and areas for future research.

Role of Hematopoietic Stem Cell Transplantation in Acute Promyelocytic Leukemia

The indication of hematopoietic stem cell transplantation (HSCT) in acute promyelocytic leukemia (APL) has evolved historically from a widespread use in front-line therapy during the pre-ATRA era to a virtual rejection of this indication for patients treated with modern treatments. HSCT in first complete remission could only be considered for an extremely small fraction of patients with persistent MRD at the end of consolidation or for those who relapse. In the pre-ATO era, relapsed patients were usually treated with readministration of ATRA and chemotherapy as salvage therapy, generally containing high-dose cytarabine and an anthracycline, followed by further post-remission chemotherapy and/or HSCT. ATO-based regimens are presently regarded as the first option for relapsed APL. The selection of the most appropriate post-remission treatment option for patients in second CR (CR2), as well as the modality of HSCT when indicated, depends on several variables, such as pre-transplant molecular status, duration of first remission, age, and donor availability. Although with a moderate level of evidence, based on recent retrospective studies, autologous HSCT would be at present the preferred option for consolidation for patients in molecular CR2. Allogeneic HSCT could be considered in patients with a very early relapse or those beyond CR2. Nevertheless, the superiority of HSCT as consolidation over other alternatives without transplantation has recently been questioned in some studies, which justify a prospective controlled study to resolve this still controversial issue.

Clinical Utility of Next-Generation Sequencing in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a genetically heterogeneous disease that, even with current advancements in therapy, continues to have a poor prognosis. Recurrent somatic mutations have been identified in a core set of pathogenic genes including FLT3 (25-30% prevalence), NPM1 (25-30%), DNMT3A (25-30%), IDH1/2 (5-15%), and TET2 (5-15%), with direct diagnostic, prognostic, and targeted therapeutic implications. Advances in the understanding of the complex mechanisms of AML leukemogenesis have led to the development and recent US Food and Drug Administration (FDA) approval of several targeted therapies: midostaurin and gilteritinib targeting activated FLT3, and ivosidenib and enasidenib targeting mutated IDH1/2. Several additional drug candidates targeting other recurrently mutated gene pathways in AML are also being actively developed. Furthermore, outside of the realm of predicting responses to targeted therapies, many other mutated genes, which comprise the so-called long tail of oncogenic drivers in AML, have been shown to provide clinically useful diagnostic and prognostic information for AML patients. Many of these recurrently mutated genes have also been shown to be excellent biomarkers for post-treatment minimal residual disease (MRD) monitoring for assessing treatment response and predicting future relapse. In addition, the identification of germline mutations in a set of genes predisposing to myeloid malignancies may directly inform treatment decisions (particularly stem cell transplantation) and impact other family members. Recent advances in sequencing technology have made it practically and economically feasible to evaluate many genes simultaneously using next-generation sequencing (NGS). Mutation screening with NGS panels has been recommended by national and international professional guidelines as the standard of care for AML patients. NGS-based detection of the heterogeneous genes commonly mutated in AML has practical clinical utility for disease diagnosis, prognosis, prediction of targeted therapy response, and MRD monitoring.

Utility of 18F-FDG PET/CT in medical care of a promyelocytic sarcoma

Promyelocytic sarcoma is an uncommon solid tumor made up of myeloblasts. It is characterized, like acute promyelocytic leukemia (APL), by a chromosomal translocation t(15;17) involving the retinoic acid receptor alpha (RARalpha) and the promyelocytic gene (PML). The diagnosis and monitoring of promyelocytic sarcoma is a challenge due to the rarity and severity of the disease. We describe a case with several initial sites and without APL. The patient was monitored with regular 18F-FDG PET/CT from diagnosis to complete response. The evolution of PET/CT imageries was compared to the quantification of PML-RARα fusion gene by RQ-PCR. In promyelocytic sarcoma medical care, 18F-FDG PET/CT appears to be an attractive tool for finding targets for biopsy, for the primary staging, for assessing therapeutic response and for detecting early relapse.

Acute myeloid leukemia with CPSF6-RARG fusion resembling acute promyelocytic leukemia with extramedullary infiltration

Some subtypes of acute myeloid leukemia (AML) share morphologic, immunophenotypic, and clinical features of acute promyelocytic leukemia (APL), but lack a PML–RARA (promyelocytic leukemia–retinoic acid receptor alpha) fusion gene. Instead, they have the retinoic acid receptor beta (RARB) or retinoic acid receptor gamma (RARG) rearranged. Almost all of these AML subtypes exhibit resistance to all-trans retinoic acid (ATRA); undoubtedly, the prognosis is poor. Here, we present an AML patient resembling APL with a novel cleavage and polyadenylation specific factor 6 (CPSF6)–RARG fusion, showing resistance to ATRA and poor response to chemotherapy with homoharringtonine and cytarabine. Simultaneously, the patient also had extramedullary infiltration.

The impact of ICAM-1, CCL2 and TGM2 gene polymorphisms on differentiation syndrome in acute promyelocytic leukemia

Background

Although arsenic trioxide (ATO) and all-trans retinoic acid (ATRA) are well-tolerated and effective treatments for Acute Promyelocytic Leukemia (APL), Differentiation Syndrome (DS) is a lethal side effect in some patients. The pathogenesis of DS is complex and not well understood; however, it is considered as an inflammatory response due to cytokines release of differentiated cells. Moreover, adhesion molecules that are widely expressed on the surface of differentiated cells and gene expression changes of transglutaminase2 (TGM2) are mechanisms involved in the development of DS. The purpose of this study was to assess the association of single nucleotide polymorphisms (SNP) of Intercellular Adhesion Molecule-1 (ICAM-1), chemokine (C-C motif) ligand 2 (CCL2) and TGM2 as inflammatory factors with differentiation syndrome susceptibility.

Methods

DNA was extracted from 133 APL patients and 100 normal controls. Assessment according to the PETHEMA criteria revealed that 13.5% of these patients experienced differentiation syndrome. Tetra-ARMS PCR and PCR-RFLP were done to amplify DNA fragments in APL patients with and without DS. Then DNA sequencing was done to validate the results. SNPStats, SPSS and Finch TV were used to analyze the results.

Results

A significant correlation was found between rs4811528 in the TGM2 gene and differentiation syndrome susceptibility (P = 0.002, 95% CI = 1.74–18.81, OR = 5.72) while rs5498 in ICAM-1, rs1024611 in CCL2, and rs7270785 in TGM2 genes showed no correlation with differentiation syndrome. The G allele of rs7270785 and rs4811528 showed a haplotypic association with differentiation syndrome (P = 0.03, 95% CI = 1.13–13.86, OR = 3.96).

Conclusions

AA genotype of the TGM2 SNP (rs4811528) may be a risk factor for development of DS in patients with APL following the use of ATRA/ATO.

Synthetic cyclopenta[b]indoles exhibit antineoplastic activity by targeting microtubule dynamics in acute myeloid leukemia cells

Acute promyelocytic leukemia (APL) is associated with PML-RARα oncogene, which is treated using all-trans retinoic acid (ATRA)-based chemotherapy. However, chemoresistance is observed in 20-30% of treated patients and represents a clinical challenge, raising the importance of the development of new therapeutic options. In the present study, the effects of three synthetic cyclopenta[b]indoles on the leukemia phenotype were investigated using NB4 (ATRA-sensitive) and NB4-R2 (ATRA-resistant) cells. Among the tested synthetic cyclopenta[b]indoles, compound 2, which contains a heterocyclic nucleus, was the most active, presenting time-dependent cytotoxic activity in the μM range in APL cells, without cytotoxicity for normal leukocytes, and was selected for further characterization. Compound 2 significantly decreased clonogenicity, increased apoptosis, and caused cell cycle arrest at S and G₂/M phases in a drug concentration-dependent manner. Morphological analyses indicated aberrant mitosis and diffuse tubulin staining upon compound 2 exposure, which corroborates cell cycle findings. In the molecular scenario, compound 2 reduced STMN1 expression and activity, and induced PARP1 cleavage and H2AX and CHK2 phosphorylation, and modulated CDKN1A, PMAIP1, GADD45A, and XRCC3 expressions, indicating reduction of cell proliferation, apoptosis, and DNA damage. Moreover, in the in vivo tubulin polymerization assay, NB4 and NB4-R2 cells showed a reduction in the levels of polymerized tubulin upon compound 2 exposure, which indicates tubulin as a target of the drug. Molecular docking supports this hypothesis. Taken together, these data indicated that compound 2 exhibits antileukemic effects through disrupting the microtubule dynamics, identifying a possible novel potential antineoplastic agent for the treatment of ATRA-resistant APL.

Hematopoietic stem cell transplantation for adults with relapsed acute promyelocytic leukemia in second complete remission

We retrospectively compared outcomes of a large series of adult patients with APL in CR2 receiving alloHSCT (n = 228) or autoHSCT (n = 341) reported to the European Society for Blood and Marrow Transplantation from January 2004 to December 2018. The 2-year cumulative incidence of non-relapse mortality was significantly higher for alloHSCT 17.3% (95% CI 12.5-22.8) compared with autoHSCT 2.7% (95% CI 1.2-5) (p = 0.001), while differences in relapse rate were not significant (28% versus 22.9%; p = 0.28). Leukemia-free survival (LFS) and overall survival (OS) favored autoHSCT with 74.5% (95% CI 69-79.2) and 82.4% (95% CI 77.3-86.5) compared with alloHSCT with 54.7% (95% CI 47.5-61.3) (p = 0.001) and 64.3% (95% CI 57.2-70.6), respectively (p = 0.001 and p = 0.001). Multivariable analysis showed significantly worse LFS after alloHSCT (HR 0.49; 95% CI 0.37-0.67; p < 0.0001), older age (p = 0.001), and shorter time from diagnosis to transplant (p = 0.00015). Similar results were obtained for OS. The study shows that autoHSCT resulted in better survival outcomes (LFS and OS) for APL in CR2. These results were mainly due to reduced NRM in the autoHSCT as compared to alloHSCT.

Current strategies for detection and approach to measurable residual disease in acute myeloid leukemia

Baseline cytogenetic/genetic features have been widely recognized to play a critical prognostic role in acute myeloid leukemia (AML) and have proven useful in designing risk-adapted treatment strategies. Nevertheless, to improve further the outcome of AML patients we are still in need of accurate methods to explore the quality of response and to adequately discriminate patients who are likely to relapse over time from those who are in deep and stable remission. In this view, is it well established that measurement of leukemic cells surviving chemotherapy (called measurable residual disease, MRD) during the course of treatment may be a reliable biomarker in predicting relapse. Detection of MRD relies on highly sensitive techniques, such as quantitative polymerase chain reaction and multiparametric flow cytometry, which, due to their levels of specificity and sensitivity, are increasingly included in the decision-making process of AML treatment. In the present manuscript, we will review the current techniques of MRD investigation and their clinical contribution to AML management.

Precision medicine in acute myeloid leukemia: where are we now and what does the future hold?

INTRODUCTION

Precision medicine has revolutionized the diagnostic and therapeutic management of acute myeloid leukemia (AML), from standardized schemes based on chemotherapy to tailored approaches according to molecular and genetic profile and targeted therapy.

AREAS COVERED

The main topics of precision medicine in AML were reviewed in MEDLINE, EMBASE, and Cochrane Central Register databases, and future directions in this therapeutic area were addressed. This review included targeted therapies, drug-sensitivity tests and predictive biomarkers, and genetic studies employing pharmacogenetic and deep sequencing strategies.

EXPERT OPINION

Precision medicine has opened the door to personalized therapy for specific AML patient populations with promising results. Several targeted therapies have been approved or are being tested for specific mutations (i.e. FLT3, IDH, BCL-2, TP53), obtaining improvements in clinical outcomes and less toxicity as compared with intensive treatment, allowing potential combination therapy. Ongoing trials and real data will establish the role of these molecules in monotherapy or combined in different AML settings (front-line, relapsed/refractory, or post-transplant). Experience in drug-sensitivity predictors and pharmacogenetic biomarkers is encouraging and could be useful tools in the next years, but we need a better understanding of AML biology and pathogenesis as well as confirmatory studies to demonstrate the utility in clinical practice.

Interleukin-8 is not a predictive biomarker for the development of the acute promyelocytic leukemia differentiation syndrome

Background

Differentiation syndrome (DS) is the main life-threatening adverse event that occurs in acute promyelocytic leukemia (APL) patients treated with all-trans retinoic acid (ATRA). Cytokine imbalances have been reported to play role during the developing of acute promyelocytic leukemia differentiation syndrome (APL-DS). However, the relationship between the plasma cytokine levels and their prognostic value for the prediction of DS developing in patients with APL during the treatment with ATRA and anthracyclines has not been previously reported.

Methods

In this study, we followed an APL cohort (n = 17) over 7 days of ATRA therapy in DS (n = 6) and non-DS groups (n = 11). Interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12p70 and TNF-α were measured in the peripheral blood plasma from 17 patients with APL and 11 healthy adult controls by using the cytometric bead array method.

Results

In non-DS patients, IL-8 plasma levels were significantly reduced in the seventh day of ATRA treatment (34.16; 6.99 to 147.11 pg mL^− 1 in D0 vs. 10.9; 0 to 26.81 pg mL^− 1 in D7; p = 0.02) whereas their levels did not discriminate between DS and non-DS development during the entire induction period (all p > 0.05 in D0, D3, and D7). No significant differences were found in IL-6 levels between groups (p > 0.05 in D0-D7). Other cytokines tested were all undetectable in patients with APL or healthy controls.

Conclusions

We demonstrated that the modulation of IL-8 following ATRA treatment may occur regardless of the development of DS and, therefore, does not appear to be a predictive biomarker to monitor the APL-DS.

The diagnostic power of CD117, CD13, CD56, CD64, and MPO in rapid screening acute promyelocytic leukemia

Objective

The same immuno-phenotype between HLA-DR-negative acute myeloid leukemia (AML) and acute promyelocytic leukemia (APL) causes APL rapid screening to become difficult. This study aimed to identify the associated antigens for APL and the best model in clinical uses.

Results

A total of 36 APL (PML–RARA+) and 29 HLA-DR-negative non-APL patients enrolled in this study. When a cut-off point of 20% events was applied to define positive or negative status, APL and non-APL patients share a similar immuno-phenotype of CD117, CD34, CD11b, CD13, CD33, and MPO (P > 0.05). However, expression intensity of CD117 (P = 0.002), CD13 (P < 0.001), CD35 (P < 0.001), CD64 (P < 0.001), and MPO (P < 0.001) in APL are significantly higher while CD56 (P = 0.049) is lower than in non-APL subjects. The Bayesian Model Averaging (BMA) analysis identified CD117 (≥ 49% events), CD13 (≥ 88% events), CD56 (≤ 25% events), CD64 (≥ 42% events), and MPO (≥ 97% events) antigens as an optimal model for APL diagnosis. A combination of these factors resulted in an area under curve (AUC) value of 0.98 together with 91.7% sensitivity and 93.1% specificity, which is better than individual markers (AUC were 0.76, 0.84, 0.65, 0.82, and 0.85, respectively) (P = 0.001).

RNA-sequencing of acute promyelocytic leukemia primary blasts reveals novel molecular biomarkers of early death events

Although acute promyelocytic leukemia (APL) has evolved to the AML entity with the best prognosis, typical 'early death' (ED) events still account for mortality rates of ∼20% in population-based studies. To investigate this poorly understood issue we performed whole transcriptome analysis of n = 7 APL ED cases compared to n = 7 APL cases with long term remission. We discovered the proteins S100A8/S100A9 and EFEMP1 as the most differentially expressed factors. In an independent cohort of n = 58 APL patients EFEMP1 over-expression was associated with a worse overall survival. Furthermore, a subgroup analysis of ED caused by hemorrhagic complications revealed an association of metallothioneins (MT1G/MT1E) with higher bleeding rates, ED events and negative prognostic effects on overall survival. Finally, we identified a novel TPM4-KLF2 fusion transcripts in 44/64 APL samples. In summary, we report a comprehensive transcriptomic analysis and novel potential biomarkers of ED biology, which highlight novel pathways in ED events in APL.

Acute myeloid leukemia during pregnancy: a single institutional experience with 17 patients and literature review

Management of acute myeloid leukemia during pregnancy (P-AML) is a challenging endeavor with limited evidence-based information available. To truly achieve the goal of improving P-AML patients, additional evidence-based research is necessary. We retrospectively reviewed cases of 17 patients diagnosed with P-AML, including seven for acute promyelocytic leukemia (APL) from January 2012 to June 2019. Among the non-APL, 90% patients (9/10) ended pregnancy prior to induction chemotherapy. The median intervals between diagnosis and start of chemotherapy were 5 days (range 1-14 days). Four patients elected to delay chemotherapy by more than one week. Of the seven APL patients, six received all-trans retinoic acid (ATRA) before the diagnostic molecular results. Five patients underwent cesarean sections (CS) and all newborns were alive (four preterm and one full-term deliveries). Overall, approximately 94% of the patients (16/17) are currently alive in remission. To treat P-AML patients in a safer manner, balancing the risk of progressing to advanced disease and proceeding with pregnancy is required. We consider a slight delay (less than 14 days) in the termination of pregnancy may not differ the prognosis to patients with non-APL. For APL, patients will benefit from prompt administration of ATRA for highly suspected cases.

Biotransformation of arsenic trioxide by AS3MT favors eradication of acute promyelocytic leukemia: revealing the hidden facts

Arsenic trioxide (ATO) is one of the most effective drugs for treatment of acute promyelocytic leukemia (APL). It could specifically target the PML/RARα fusion oncoprotein stability and induces APL cell differentiation as well as apoptosis. Although many studies have been conducted to document the anticancer effects and mechanism of ATO, there is little information about the association between biotransformation of ATO to active arsenic metabolites and APL therapy. Generally, ATO can be rapidly converted into trivalent methylated metabolites by arsenic (+3 oxidation state) methyltransferase (AS3MT) mostly in liver and redistributed to bloodstream of APL patients who receiving ATO treatment, thereby leading to a balance between cytotoxicity and differentiation, which is proposed to be the key event in successful treatment of APL. In this review, we comprehensively discussed possible roles of AS3MT and methylated arsenic metabolites in APL therapy, so as to reveal the association between individual differences of AS3MT expression and activity with the therapeutic efficacy of ATO in APL patients.

Role of hematopoietic cell transplantation in relapsed acute promyelocytic leukemia

The use of all trans-retinoic acid and arsenic trioxide combination as the induction regimen for acute promyelocytic leukemia (APL) has revolutionized the management and outcomes of this disease. Modern risk-adapted frontline therapy has provided excellent therapeutic results. However, significant numbers of APL patients relapse after frontline therapy, and the optimal management strategy for relapsed APL, specifically the role and type of hematopoietic cell transplantation (HCT) are still to be defined. Both autologous and allogeneic HCTs are associated with durable remission and prolonged survival when utilized in appropriate disease settings. Once remission has been achieved, consolidation with autologous HCT for APL patients with negative minimal residual disease (MRD) status, and with allogeneic HCT for APL patients with positive MRD status appear to offer the best long-term outcomes. In this article, we provide a comprehensive review of existing literature on the efficacy of HCT in treatment of relapse/refractory APL and we discuss the appropriate use of this modality.

Measurable residual disease after the first consolidation predicts the outcomes of patients with acute promyelocytic leukemia treated with all-trans retinoic acid and chemotherapy

We stratified patients with newly diagnosed acute promyelocytic leukemia (APL) according to a white blood cell (WBC) count of ≥ 3 × 10⁹/L (high risk) or < 3 × 10⁹/L (low risk) before administering risk-adapted chemotherapy in combination with all-trans retinoic acid (ATRA). In total, 27 low-risk and 23 high-risk patients were assigned to receive induction and three courses of consolidation with ATRA and anthracycline, followed by 2-year maintenance regimen. High-risk group additionally received cytarabine during 1st consolidation and another one-shot idarubicin treatment during 3rd consolidation. We prospectively monitored measurable residual disease (MRD) after induction and each consolidation. In the low-risk and high-risk groups, 5-year disease-free survival (DFS) rates were 86.5% and 81.2% (p = 0.862), and 5-year overall survival rates were 100% and 84.8% (p = 0.062), respectively. In the MRD-negative and MRD-positive groups, 5-year DFS rates were 91.7% and 78.4% (p = 0.402) and 84.7% and 60.0% (p = 0.102) after induction and 1st consolidation, respectively. Relapse rates were 8.3% and 13.3% (p = 0.570) and 9.0% and 40.0% (p = 0.076) after induction and 1st consolidation, respectively. Achieving MRD-negativity after 1st consolidation, rather than after induction, was a potential predictor of relapse and DFS in patients with APL treated with ATRA + chemotherapy.

When Poisons Cure: The Case of Arsenic in Acute Promyelocytic Leukemia

Arsenic has been known for centuries for its double-edged potential: a poison and at the same time a therapeutic agent. The name "arsenikon," meaning "potent," speaks itself for the pharmaceutical properties of this compound, questioned and analyzed for at least 2000 years. In the last decades, acute promyelocytic leukemia (APL) has evolved from a highly fatal to a curable disease, due to the use of all-trans-retinoic acid and, more recently, arsenic trioxide combinations. The success of these entirely chemo-free regimens increased the awareness of APL and reduced the prevalence of early deaths, which was an impending issue in this disease. Further improvements are expected with the next use of oral arsenic formulations, which will allow a complete outpatient approach, at least in the post-induction settings, further improving patients' quality of life. The wide use of standardized approaches in APL will also help unravel long-standing open questions, including the pathogenesis, prevention, and treatment of the differentiation syndrome and of short-term organ toxicities. In the long term, the study of survivorship issues, such as fertility and organ-related and psychological damages, in the increasing number of survivors will help further improve their life after APL.

Detection and management of acute myeloid leukemia measurable residual disease: is it standard of care?

PURPOSE OF REVIEW

In the present manuscript, we will review the current approaches to investigate measurable residual disease (MRD) and its clinical applications in AML management.

RECENT FINDINGS

Over the last decades, several methods have been developed to trace MRD, with flow cytometry and polymerase chain reaction (PCR) being the most reliable. However, new technologies, such as digital PCR and Next-Generation Sequencing are emerging as particularly useful in AML. The 2017 European LeukemiaNet (ELN) recommendations have incorporated MRD assessment to define the response criteria to therapy, and more recently, the ELN MRD Working Party has published guidelines for the use of MRD in clinical practice.

SUMMARY

Morphologic complete remission (mCR) after induction therapy, has been consistently shown not only to have a critical prognostic role but also to fail in predicting relapse on an individual basis. Major attempts to improve our prediction capability have been made by measuring the residual levels of leukemic cells that persist in the bone marrow after chemotherapy. This number of cells, also called MRD, harbors in the bone marrow below the threshold of morphology and is responsible for leukemia recurrence. Therefore, the detection of MRD promises to help predict the risk of relapse, allowing a more proper patients' risk-stratification and the use of risk-tailored therapeutic strategy.

PLZF-RARα, NPM1-RARα, and Other Acute Promyelocytic Leukemia Variants: The PETHEMA Registry Experience and Systematic Literature Review

It has been suggested that 1–2% of acute promyelocytic leukemia (APL) patients present variant rearrangements of retinoic acid receptor alpha (RARα) fusion gene, with the promyelocytic leukaemia zinc finger (PLZF)/RAR_α being the most frequent. Resistance to all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO) has been suggested in PLZF/RAR_α and other variant APLs. Herein, we analyze the incidence, characteristics, and outcomes of variant APLs reported to the multinational PETHEMA (Programa para el Tratamiento de Hemopatias Malignas) registry, and we perform a systematic review in order to shed light on strategies to improve management of these extremely rare diseases. Of 2895 patients with genetically confirmed APL in the PETHEMA registry, 11 had variant APL (0.4%) (9 PLZF-RAR_α and 2 NPM1-RAR_α), 9 were men, with median age of 44.6 years (3 months to 76 years), median leucocytes (WBC) 16.8 × 10⁹/L, and frequent coagulopathy. Eight patients were treated with ATRA plus chemotherapy-based regimens, and 3 with chemotherapy-based. As compared to previous reports, complete remission and survival was slightly better in our cohort, with 73% complete remission (CR) and 73% survival despite a high relapse rate (43%). After analyzing our series and performing a comprehensive and critical review of the literature, strong recommendations on appropriate management of variant APL are not possible due to the low number and heterogeneity of patients reported so far.

Hematopoietic stem cell transplantation for pediatric acute promyelocytic leukemia in Japan

BACKGROUND

The number of hematopoietic stem cell transplantation (HSCT) procedures performed for pediatric acute promyelocytic leukemia (APL) has decreased in the all-trans retinoic acid (ATRA) era. Although HSCT is still widely adopted as part of salvage therapy for relapsed patients, there is no general consensus about the optimal transplant type (autologous [auto-HSCT] or allogeneic HSCT [allo-HSCT]).

PROCEDURES

We retrospectively reviewed the clinical data of 95 childhood APL patients who underwent their first HSCT between 1990 and 2014. Of the 95 patients, 40 (42%), 41 (43%), and 3 (3%) underwent HSCT procedures after achieving their first complete remission (CR1), CR2, and CR3, respectively, and 11 (12%) underwent HSCT while in a non-CR state.

RESULTS

The non-CR group exhibited significantly worse five-year overall survival (5yOS) and disease-free survival (5yDFS) (5yOS: 46%; 5yDFS: 46%) than the CR1 (5yOS: 80%; 5yDFS: 78%) and CR2 + CR3 groups (5yOS: 81%; 5yDFS: 76%) (P = 0.013 and P < 0.01, respectively). Of the patients treated in CR2, no significant differences in 5yOS or the five-year cumulative incidence of relapse (5yRI) were detected between the auto-HSCT and allo-HSCT groups (5yOS: 85%, vs 78%, P = 0.648; 5yRI: 9%, vs 11%, P = 0.828). Among the patients who underwent allo-HSCT in CR2, those with matched sibling donors displayed a significantly higher 5yRI (33%) than those with other types of donors (0%, P = 0.015).

CONCLUSIONS

Even after relapsing, childhood APL can be cured with HSCT if CR is achieved. These findings demonstrate that achieving CR followed by HSCT is the preferred strategy for treating children with relapsed or refractory APL.

Acute Promyelocytic Leukemia during Pregnancy: A Systematic Review of the Literature

The management of pregnant women with acute promyelocytic leukemia (APL) is a challenging situation where limited evidence-based information is available. We performed a systematic literature review to analyze the outcomes reported for both mother and fetus when APL is diagnosed during pregnancy. PubMed, Scopus and Web of Science databases were systematically searched to identify studies reporting cases of APL during pregnancy. Sixty-six articles met the eligibility criteria (53 single case reports). Ninety-two patients were eligible for induction therapy, with most them being treated with all-trans retinoic acid alone (32%) or combined with chemotherapy (43%), while the remaining patients received chemotherapy alone. Three patients were treated with arsenic-based regimens after delivery. Overall complete remission rate was 89%, with no statistically significant differences according to the type of induction and gestational age. During the first trimester, women were more likely to experience spontaneous and induced abortion compared to those during the second trimester (88% vs. 30%) (p < 0.0001), while only one patient diagnosed during the third trimester terminated in stillbirth. Twelve of 16 infants with neonatal complications had respiratory distress syndrome. Except two early deaths (Potter's syndrome and pulmonary hemorrhage), all neonates evolved favorably. This study confirms that gestational age does not affect the results in the mother, but is closely related to fetal viability. Our results may be useful for the process of decision making that requires the involvement of the patient, hematologist, obstetrician and neonatologist.

Treatment of acute promyelocytic leukemia in older patients: recommendations of an International Society of Geriatric Oncology (SIOG) task force

Approximately one third of patients diagnosed with acute promyelocytic leukemia (APL) are above the age of sixty. It is important to ensure older adults receive optimal diagnosis and management since this subtype of acute myeloid leukemia - given appropriate treatment - is highly curable with lower risk of adverse events compared to other types of leukemia. Historically, older age has been a risk factor for early death and poorer overall survival. However, prospects have changed with the introduction of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). APL is curable in the majority of patients regardless of age, and the threshold of fitness that makes ATRA/ATO therapy possible is likely to be lower than for cytotoxic chemotherapy. APL frequently presents as a medical emergency and rapid diagnosis and intervention - typically involving referral to a specialist centre - is a major determinant of outcome. After diagnosis, management of APL in older adults presents particular challenges. Geriatric assessment, including evaluation of frailty, comorbidities and polypharmacy can assist in providing optimal supportive care for older adults during remission induction and may help individualize therapy in the post-remission phase. Here, we review the available evidence, highlighting areas of consensus, gaps in evidence and opportunities for research to enhance diagnosis, management and survivorship for older patients.

Arsenic Trioxide Treatment during Pregnancy for Acute Promyelocytic Leukemia in a 22-Year-Old Woman

Acute leukemia during pregnancy is rare (1 for 100000 pregnancies). The association of arsenic trioxide (ATO) and all-trans retinoic acid (ATRA) is known as the best therapy in standard-risk acute promyelocytic leukemia (APL). We describe the first case of a pregnancy with ATRA and ATO reported in the literature. In March 2018 at the University Hospital of Besançon, a 22-year-old woman was diagnosed with APL at 14 weeks of gestation (WG). She received a total of 2160 mg of ATRA and 930 mg of ATO between 14 and 35 WG. The mother's cytological remission was very fast. No maternal or fetal complications occurred during pregnancy. The pediatrics outcomes were good. Many case reports about ATRA exposure during the second and third trimesters report no serious adverse effect for pregnancy. ATO is teratogenic, genotoxic, and carcinogenic and passes through the placenta. Fetal exposure seems to be associated with bad pregnancy outcomes (preterm delivery, decreased birth weight, and fetal loss) and with lung diseases in young adults. No clinical trial is obviously possible, and the only data available are environmental exposure or animal studies. This case report may help medical teams to make hard decision for a treatment of APL during pregnancy.

Identification of relapse-associated gene mutations by next-generation sequencing in low-risk acute myeloid leukaemia patients

Recommended genetic categorization of acute myeloid leukaemias (AML) includes a favourable-risk category, but not all these patients have good prognosis. Here, we used next-generation sequencing to evaluate the mutational profile of 166 low-risk AML patients: 30 core-binding factor (CBF)-AMLs, 33 nucleophosmin (NPM1)-AMLs, 4 biCEBPα-AMLs and 101 acute promyelocytic leukaemias (APLs). Functional categories of mutated genes differed among subgroups. NPM1-AMLs showed frequent variations in DNA-methylation genes (DNMT3A, TET2, IDH1/2) (79%), although without prognostic impact. Within this group, splicing-gene mutations were an independent factor for relapse-free (RFS) and overall survival (OS). In CBF-AML, poor independent factors for RFS and OS were mutations in RAS pathway and cohesin genes, respectively. In APL, the mutational profile differed according to the risk groups. High-risk APLs showed a high mutation rate in cell-signalling genes (P = 0·002), highlighting an increased incidence of FLT3 internal tandem duplication (ITD) (65%, P < 0·0001). Remarkably, in low-risk APLs (n = 28), NRAS mutations were strongly correlated with a shorter five-year RFS (25% vs. 100%, P < 0·0001). Overall, a high number of mutations (≥3) was the worst prognostic factor RFS (HR = 2·6, P = 0·003). These results suggest that gene mutations may identify conventional low-risk AML patients with poor prognosis and might be useful for better risk stratification and treatment decisions.

Educational Case: Systemic Mastocytosis with an Associated Hematological Neoplasm

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, seehttp://journals.sagepub.com/doi/10.1177/2374289517715040.¹

Outcome of older (≥70 years) APL patients frontline treated with or without arsenic trioxide-an International Collaborative Study

Data on outcome in older (≥70 years) patients with acute promyelocytic leukemia after treatment with arsenic trioxide (ATO) compared with standard chemotherapy (CTX) is scarce. We evaluated 433 patients (median age, 73.4 years) treated either with ATO+ all-trans retinoic acid (ATO/ATRA; n = 26), CTX/ATRA + ATO during consolidation (CTX/ATRA/ATO; n = 148), or with CTX/ATRA (n = 259). Median follow-up for overall survival (OS) was 4.8 years. Complete remissions (CR) were achieved in 92% with ATO/ATRA and 82% with CTX/ATRA; induction death rates were 8% and 18%, respectively. For analysis of postremission outcomes we combined the ATO/ATRA and CTX/ATRA/ATO groups (ATO/ATRA ± CTX). Cumulative incidence of relapse (CIR) was significantly lower after ATO/ATRA ± CTX compared with CTX/ATRA (P < 0.001). The same held true when restricting the analysis according to the treatment period after the year 2000. OS of patients in CR1 was not different between ATO/ATRA ± CTX compared with CTX/ATRA (P = 0.20). High (>10 × 10⁹/l) white blood cell (WBC) counts at diagnosis were associated with higher CIR (P < 0.001) compared with lower WBC in the CTX/ATRA group, but not in the ATO/ATRA ± CTX group (P = 0.48). ATO, when added to ATRA or CTX/ATRA is feasible and effective in elderly patients for remission induction and consolidation, particularly in patients with high WBC at diagnosis.

Follow-up and outcome of the twelve-year experience in adult patients with acute promyelocytic leukemia

Acute promyelocytic leukemia is a subtype of acute myeloid leukemia, characterized by the presence of neoplastic promyelocytes, due to the reciprocal balanced translocation between chromosomes 15 and 17. Currently, with the use of agents that act directly on this molecular change, such as all-trans retinoic acid and arsenic trioxide, APL has shifted from a highly mortal to a curable disease. However, some cases are still at high risk of death, especially early death, and acquiring a better understanding of the clinical and biological factors involving APL is needed to correctly identify and treat such cases. The early suspected diagnosis and prompt initiation of the target therapy are important for better response rates. The follow-up and outcomes, using real-life data from 44 consecutive APL patients, were studied between 2001 and 2013. The overall survival rate was 82.7% and early death was 16%. Almost all patient deaths were due to severe bleeding, which was confirmed by multivariate analysis, as the most important prognostic factor leading to death. A better understanding the pathogenesis of the hemorrhagic complications in APL is needed, as well as the risk factors associated with early death in APL patients, as this has become synonymous with overall mortality.