Characteristics and predictors of early hospital deaths in newly diagnosed APL: a 13-year population-wide study

Study on clinical features of early death in older patients with acute promyelocytic leukemia

This study aimed to analyze the baseline clinical characteristics, as well as the clinical features and risk factors of early death (ED) in older patients with acute promyelocytic leukemia (APL). A retrospective analysis was conducted on 198 consecutive older patients (age ≥ 50 years) with newly diagnosed APL who received arsenic trioxide alone as induction therapy, with 354 younger patients (age < 50 years) as controls. Ten easily obtainable clinical parameters were selected. Compared with the younger group, the older group had less fever, lower white blood cell (WBC) count, lower levels of albumin, and higher levels of creatinine upon admission. While the younger group had higher levels of aspartate aminotransferase and lower levels of fibrinogen (all P < 0.05). The ED rate was significantly higher in the older group (21.7% vs. 12.4%; P = 0.004). The causes of ED in the older group were bleeding, infection, embolism, differentiation syndrome, and others, in order of incidence. The cumulative incidence of ED due to infection (P = 0.0003) and embolism (P = 0.034) was significantly higher in the older group. For the older patients, independent risk factors for ED were WBC count > 5.9 × 109 /L, albumin < 35.85 g/L, creatinine > 72.9 µmol/L and fibrinogen < 1.137 g/L; independent risk factor for bleeding ED was WBC count > 6.2 × 109 /L; while independent risk factors for infection ED were albumin < 36.55 g/L and fibrinogen < 1.035 g/L. The baseline clinical characteristics, the clinical features and risk factors of ED in older APL patients were all quite different from those in younger patients, so research specifically targeting older patients with APL is very necessary.

Risk factors and remaining challenges in the treatment of acute promyelocytic leukemia

The treatment of acute promyelocytic leukemia (APL) has evolved with the introduction of all-trans retinoic acid (ATRA) and subsequent arsenic trioxide (ATO), particularly in standard-risk APL with an initial white blood cell count (WBC) < 10,000/μL, where a high cure rate can now be achieved. However, for some patients with risk factors, early death or relapse remains a concern. Insights from the analysis of patients treated with ATRA and chemotherapy have identified risk factors such as WBC, surface antigens, complex karyotypes, FLT3 and other genetic mutations, p73 isoforms, variant rearrangements, and drug resistance mutations. However, in the ATRA + ATO era, the significance of these risk factors is changing. This article provides a comprehensive review of APL risk factors, taking into account the treatment approach, and explores the challenges associated with APL treatments.

Chemotherapy-free approaches to newly-diagnosed acute promyelocytic leukaemia: is oral-arsenic trioxide/all-trans retinoic acid/ascorbic acid the answer?

INTRODUCTION

Acute promyelocytic leukemia (APL) is a distinct form of acute myeloid leukemia characterized by the presence of t(15;17)(q24;21) and the PML:RARA gene fusion. Frontline use of intravenous arsenic trioxide (i.v.-ATO) and all-trans retinoic acid (ATRA) has vastly improved cure rates in APL. Researchers in Hong Kong invented the oral formulation of ATO (oral-ATO) and have confirmed a bioavailability comparable to i.v.-ATO. A plethora of studies have confirmed the safety and efficacy of oral-ATO-based regimens in the frontline and relapsed setting.

AREAS COVERED

Aspects on the development of oral-ATO-based regimens for APL in the frontline and relapsed setting are discussed. The short-term and long-term safety and efficacy of oral-ATO-based regimens are discussed. The frontline use of oral-ATO in combination with ATRA and ascorbic acid (AAA) induction in a 'chemotherapy-free' is highlighted.

EXPERT OPINION

Current and ongoing data on the use of oral-ATO-based regimens in APL support the use of oral-ATO as an alternative to i.v.-ATO allowing a more convenient and economical approach to the management of APL.

Clinical characteristics and analysis of related factors associated with early death in newly diagnosed patients with acute promyelocytic leukemia

OBJECTIVE

The objective of this study was to investigate the clinical characteristics and analysis of related factors associated with early death in newly diagnosed patients with acute promyelocytic leukemia (APL).

METHODS

This retrospective study included patients who visited our hospital between January 2010 and August 2022 and were diagnosed with APL for the first time. We analyzed their clinical and laboratory characteristics and analysis of related factors associated with early death.

RESULTS

A total of 269 patients with a primary diagnosis of APL were collected. The male to female ratio was 6:5, and the median age was 42 years (range 7-80). Among patients with initial APL diagnosis, there were 34 early deaths, resulting in an early mortality rate of 13%. The median time from diagnosis to death was 8.5 days (range 3-24). Comparative analysis of the clinical characteristics between patients who died early and those who did not, using a logistic regression model, revealed that age, white blood cell count (WBC) at initial diagnosis, and prolongation time of prothrombin time (PT) were independent risk factors for early death in patients with primary APL (P < 0.05). Comparing the clinical characteristics during hospitalization between the early death group and the non-early death group, it was observed that the daily mean of WBC during hospitalization was significantly higher in patients who died early than in those who did not (P < 0.001). Conversely, the daily mean of platelet count (PLT) was significantly lower in patients who died early compared to those who did not (P < 0.001). Furthermore, statistically significant differences were found in the mean daily infusion of PLT (P < 0.05), fibrinogen (Fib) (P < 0.05), and fresh frozen plasma (FFP) (P < 0.05) during hospitalization between patients who died early and those who did not. Specifically, the mean daily infusion of PLT and FFP was significantly higher in the early-death group than in the non-early-death group. Cerebral hemorrhage was identified as the immediate cause of death in 25 out of the 34 early-death patients (74%). The remaining causes of death included infection in 5 cases (15%), all of which were severe pulmonary infections, including 2 cases of combined differentiation syndrome, and abandonment of treatment in 4 patients (11%) at initial diagnosis.

CONCLUSION

In patients with primary APL, age, WBC at initial diagnosis, and PT prolongation time were identified as independent risk factors for early death (P < 0.05). Laboratory findings regarding WBC and PLT during hospitalization, as well as the infusion of PLT, Fib, and FFP during hospitalization, were also statistically significant. Cerebral hemorrhage was found to be the main cause of early death in patients with primary APL.

Machine learning-based model for predicting outcomes in cerebral hemorrhage patients with leukemia

BACKGROUND AND PURPOSE

Intracranial hemorrhage (ICH) in leukemia patients progresses rapidly with high mortality. Limited data are available on imaging studies in this population. The study aims to develop prediction models for 7-day and short-term mortality risk based on the non-contrast computed tomography (NCCT) image features.

METHODS

The NCCT image features of ICH in 135 leukemia patients between 2007-2023 were retrospectively extracted using manual assessment and radiomics methods. After multiple imputation of missing laboratory data, univariate logistic regression and least absolute shrinkage and selection operator (LASSO) were used for feature selection. Random forest models were built with comprehensive evaluation and ranking of feature importance.

RESULT

135 and 129 patients were included in the studies for 7-day and short-term prognostic models, respectively. The median age of all enrolled patients was 35 years, and there were 86 male patients (63.7 %). Clinical models (validation: AUC [area under the curve] = 0.78, AUPRC [area under the precision-recall curve] = 0.73; AUC = 0.84, AUPRC = 0.86), radiomics models (validation: AUC = 0.82, AUPRC = 0.78; AUC = 0.75, AUPRC = 0.77), and the combined models (validation: AUC = 0.84, AUPRC = 0.83; AUC = 0.87, AUPRC = 0.89) predicted 7-day and short-term mortality with good predictive efficacy. Clinical decision curve analysis showed that the combined models predicted 7-day and 30-day risk of death would be more beneficial than other models. Shape features contributed significantly more than semantic features in both radiomics models and combined models (93.3 %, 52.1 %, as well as 85.2 %,37.4 %, respectively) for 7-day and 30-day mortality.

CONCLUSIONS

Combined models constructed based on NCCT perform well in predicting the risk of 7-day and short-term mortality in ICH patients with leukemia. Shape features extracted by radiomics are important markers for modeling the prognosis.

Acute promyelocytic leukemia in children cancer hospital Egypt

BACKGROUND

Pediatric acute promyelocytic leukemia (APL) accounts for 5 to 15% of all myelocytic leukemia. A retrospective analysis of pediatric patients diagnosed and treated with APL was conducted at CCHE from July 2012 to the end of December 2019, to report the prevalence, clinical characteristics, results, and risk factors associated with induction failure and early death.

RESULT

Sixty-two patients were reported, with an age greater than ten, an initial poor coagulation profile, and a total leukocyte count (TLC) greater than 30 103/mm3 influencing 5-year overall (OS) and event-free survival (EFS), as well as a high promyelocyte count affecting 5-year EFS. Patients received a regimen based on the COG AAML0631 protocol. High-risk patients with an initial TLC > 10 × 103/mm3 and an initial promyelocytic count of 30% or more with a substantial P-value are prognostic markers for early death during induction. In females, wild FLT3 increases the risk of differentiation syndrome (DS). Receiving steroids with all-trans retinoic acid (ATRA) induction may reduce the occurrence of DS. Relapse alters the outcome. In the current study, 45 patients are alive in complete remission, with a 5-year OS of 72.5% and a 5-year EFS of 69.4%, respectively.

CONCLUSION

Pediatric APL outcomes are influenced by age above 10, an initial poor coagulation profile, and a promyelocyte count of more than 10%. An initial leukocyte count of more than 10 × 103/mm and an initial promyelocytic count of more than 30% increase the risk of early death. Receiving steroids with ATRA may reduce the occurrence of DS.

Risk stratification for early mortality in newly diagnosed acute promyelocytic leukemia: a multicenter, non-selected, retrospective cohort study

Introduction

Despite the current effective treatments for acute promyelocytic leukemia (APL), early mortality (EM), defined as death within 30 days of presentation, is a major hurdle to long-term survival.

Methods

We performed a multicenter retrospective study to evaluate the incidence and clinical characteristics of EM in patients with newly diagnosed APL and to develop a risk stratification model to predict EM.

Results

We identified 313 eligible patients diagnosed between 2000 and 2021 from five academic hospitals. The median age was 50 years (range 19-94), and 250 (79.9%) patients were <65 years. Most patients (n=274, 87.5%) received their first dose of all-trans retinoic acid (ATRA) within 24 hours of presentation. EM occurred in 41 patients, with a cumulative incidence of 13.1%. The most common cause of EM was intracranial hemorrhage (n=22, 53.6%), and most EMs (31/41, 75.6%) occurred within the first seven days of APL presentation. In a multivariable analysis, we identified three independent factors predicting EM: age ≥65 years (HR, 2.56), white blood cell count ≥8.0 x 109/L (HR, 3.30), and ATRA administration >24 hours of presentation (HR, 2.95). Based on these factors, patients were stratified into three categories with a significantly increasing risk of EM: 4.1% for low risk (54.3%; no risk factors; HR 1), 18.5% for intermediate risk (34.5%; 1 factor; HR 4.81), and 40.5% for high risk (11.2%; 2-3 factors; HR 13.16).

Discussion

The risk of EM is still not negligible in this era of ATRA-based therapies. Our risk model serves as a clinically useful tool to identify high-risk patients for EM who may be candidates for novel treatments and aggressive supportive strategies.

How to avoid early mortality in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL), a phenotypically and genotypically unique subtype of acute myeloid leukemia, has seen unprecedented advances in its management since the introduction of all-trans retinoic acid (ATRA) and arsenic trioxide. However, the phenomenal pharmacologic conversion of this once highly fatal disease to one with a long-term survival exceeding 90% among patients who survive induction remains impaired by the significant incidence of early death (ED) reaching 30% in some real-world studies. The key driver for ED in APL is catastrophic hemorrhage with a proclivity for cranial sites. Most EDs in APL are currently considered preventable. Here, we discuss the concept of early death in APL and its characteristics. Importantly, we outline implementable strategies to reduce the incidence of ED. Early recognition of APL underpins these preventive measures as significant delays in the diagnosis increase the likelihood of ED. While early administration of ATRA is often taught to all hematology trainees, this lifesaving intervention is only possible if providers, including those in emergency departments and urgent/immediate care settings, are trained to have a high index of suspicion and competence to recognize the morphologic and clinical characteristics of the disease. Other proposed strategies tackle the complications that can be present at diagnosis or arise during induction therapy and address the issues of expert consultation and protocol adherence in the management of these patients. While some of these measures appear intuitive and others aspirational, widespread adoption could bring about an era of cure for almost every patient with APL.

Acute promyelocytic leukaemia: population-based study of epidemiology and outcome with ATRA and oral-ATO from 1991 to 2021

BACKGROUND

The epidemiology and treatment of acute promyelocytic leukaemia (APL) are changing. We have incorporated oral arsenic trioxide (oral-ATO) into induction/maintenance.

METHODS

Newly-diagnosed APL from 1991 to 2021 divided into three 10-year periods were studied to define its epidemiology and how oral-ATO impacted on its outcome. Primary endpoints included APL incidence, early deaths (ED, first 30 days), and overall survival (OS). Secondary endpoints included post-30-day OS, relapse-free survival (RFS), and incidence of second cancers.

RESULTS

APL occurred in 374 males and 387 females at a median age of 44 (1-97) years. Annual incidences increased progressively, averaging 0.32 per 100,000 people. All-trans retinoic acid (ATRA)-based and oral-ATO-based regimens were used in 469 and 282 patients. There were 144 EDs, occurring almost exclusively in ATRA-based inductions (N = 139), being more with males, age > 50 years, leucocyte > 10 × 10⁹/L, diagnosis during 1991-2009 and fewer with oral-ATO-based regimens. After a median of 75 (interquartile range: 14-161) months, 5-year and 10-year OS were 68.1% and 63.3%, inferior with males, age > 50 years, leucocyte > 10 × 10⁹/L, high-risk Sanz score and superior with oral-ATO-based regimens. Factoring out EDs, 5-year and 10-year post-30-day OS were 84.0% and 78.1%, inferior with males and superior with oral-ATO-based regimens. In 607 CR1 patients, the 5-year RFS was 83.8%, superior with diagnosis in 2010-2021 and oral-ATO-based regimens. Second cancers developed in 21 patients, unrelated to oral-ATO-based regimens.

CONCLUSIONS

There was an increasing incidence of APL, and all survivals were superior with the use of oral-ATO-based regimens. This study formed part of the Acute Promyelocytic Leukaemia Asian Consortium Project (ClinicalTrials.gov identifier: NCT04251754).

Clinical outcomes of therapeutic leukapheresis in acute promyelocytic leukemia: A single-center retrospective cohort study

BACKGROUND

In acute promyelocytic leukemia (APL), increased cell burden in the peripheral blood due to either the disease itself or early treatment with all-trans retinoic acid could cause hyperleukocytosis (HL) before induction chemotherapy. However, therapeutic leukapheresis has seldom been used because of concerns of subsequent coagulopathy after this invasive procedure. The aim of this study was to evaluate the effects of leukapheresis in APL, especially for efficacy and safety.

METHODS

We retrospectively analyzed newly diagnosed patients with APL from January 2009 to March 2022. Among 323 patients, 85 had white blood cell count above 40 × 10⁹/L before induction chemotherapy. Thirty-nine patients were initially treated with leukapheresis, whereas the other 46 were not. Clinical and laboratory parameters between these groups were compared.

RESULTS

There was a trend toward favorable 30-day survival rate for the leukapheresis group compared with the non-leukapheresis group (76.9% and 67.4%; P = 0.24). The complications including subsequent intensive unit care (P = 0.23), severe hemorrhagic events (P = 0.13) showed no significant differences between the two groups. The patients were divided into subcohorts, and the survival rates of the leukapheresis and non-leukapheresis groups were 92.3% (95% confidence interval [CI], 77.8%-100.0%) versus 58.3% (95% CI, 38.6%-78.1%) (P = 0.03) in "sequential HL" and 76.7% (95% CI, 61.5%-91.8%) versus 54.8% (95% CI, 37.3%-72.4%) (P = 0.03) in "symptomatic HL," respectively. Moreover, in the "sequential HL" subcohort, the cumulative incidence of differentiation syndrome and following adverse events were significantly lower in the leukapheresis group.

CONCLUSIONS

In APL with "sequential HL" or "symptomatic HL" from either the disease itself or the effect of all-trans retinoic acid, therapeutic leukapheresis could be applied to reduce leukemic cell burden without significant risks.

Improvement of Early Death in Acute Promyelocytic Leukemia: A Population-Based Analysis

BACKGROUND

Early death is a major factor of treatment failure in acute promyelocytic leukemia (APL), however, the recent trends in the incidence of early death based on the population-level are not clear. Hence, this study is aimed at describing the incidence, recent trends, causes and characteristics of early death in APL based on the real world.

MATERIALS AND METHODS

APL patients diagnosed from 1986 to 2015 in the Surveillance, Epidemiology, and End Results (SEER) dataset were enrolled, and categorized based on gender, age, year of diagnosis, race, marital status, resident county and socioeconomic status (SES). The risk factors for all-cause and acute myelocytic leukemia (AML) specific early death were determined by univariate and multivariate logistic regression analyses, and stratified analysis was conducted by age.

RESULTS

Overall, 3212 APL patients were included in analysis between 1986 and 2015, of which a total of 683 (21.3%) patients were noted for early death. Significant differences were recognized for patient distribution by age, year of diagnosis, marital status, and SES. The early death rate of APL patients diagnosed during 2006-2015 was significantly lower than that of the early stage, but this trend was not evident in juvenile patients. At the same time, older age, and lower SES score were independent risk factors for early death in the multivariate analysis.

CONCLUSION

We established that the early death trend in APL has decreased over the past few years, but the early death rate remains high, especially in older patients and those with lower SES.

Effects of peripheral blood leukocyte count and tumor necrosis factor-alpha on early death in acute promyelocytic leukemia

BACKGROUND

Early death remains a major factor in survival in APL. We aimed to analyze the risk factors for differentiation syndrome and early death in acute promyelocytic leukemia (APL).

METHODS

The clinical data of APL patients who were newly diagnosed at Mianyang Central Hospital from January 2013 to January 2022 were retrospectively analyzed.

RESULTS

Eighty-six newly diagnosed APL patients (37 males and 49 females) were included in this study. The median age was 46 (17-75) years. Sixty-one patients (70.9%) had low/intermediate-risk APL, and 25 patients (29.1%) had high-risk APL. The incidence of differentiation syndrome (DS) was 62.4%. The multivariate analysis showed that a peak white blood cell (WBC) count ≥16 × 10^9/L was an independent risk factor (OR = 11.000, 95% CI: 2.830-42.756, P = 0.001) for DS in all APL patients, while a WBC count ≥10 × 10^9/L on Day 5 was an independent risk factor for DS in low-intermediate risk APL patients (OR = 9.114, 95% CI: 2.384-34.849, P = 0.001). There were 31 patients (36.5%) with mild DS and 22 patients (25.9%) with severe DS. The multivariate analysis showed that WBC count ≥23 × 10^9/L at chemotherapy was an independent risk factor for severe DS (OR = 10.500, 95% CI: 2.344-47.034, P = 0.002). The rate of early death (ED) was 24.4% (21/86). The multivariate analysis showed that male gender (OR = 7.578,95% CI:1.136-50.551, P = 0.036), HGB < 65 g/L (OR = 16.271,95% CI:2.012-131.594, P = 0.009) and WBC count ≥7 × 10^9/L on Day 3(OR = 23.359,95% CI:1.825-298.959, P = 0.015) were independent risk factors for ED. The WBC count at diagnosis, WBC count on Day 3 and WBC count on Day 5 had moderate positive correlations with tumor necrosis factor-α (TNF-α) at diagnosis, and the correlation coefficients were 0.648 (P = 0.012), 0.615 (P = 0.033), and 0.609 (P = 0.035), respectively. The WBC count had no correlation with IL-6.

CONCLUSION

During induction treatment, cytotoxic chemotherapy may need to be initiated to reduce the risk of DS for APL patients with a low-intermediate risk WBC count ≥10 × 10^9/L on Day 5 or for all patients with a peak WBC count ≥16 × 10^9/L. Patients with WBC > 7 × 10^9/L on Day 3 have a higher risk of ED. Leukocyte proliferation is associated with TNF-α rather than IL-6, and TNF-α may be a potential biomarker for predicting ED.

Coagulopathy in Patients with Low/Intermediate Risk Acute Promyelocytic Leukemia treated with First Line Arsenic Trioxide in Combination with All-Trans Retinoic Acid: A Monocentric Experience

No abstract  

The characteristics and long-term outcomes of acute promyelocytic leukemia patients with early intracranial hemorrhage

Intracranial hemorrhage (ICH) is a major cause of early death (ED) and leads to poor prognosis in acute promyelocytic leukemia (APL). We retrospectively described 27 unselected APL patients who experienced early ICH. The ED rate was 37%. The 3-year overall survival (OS) rate was 45.4%, while the 3-year OS rate of patients who survived through induction therapy was 87.5%. No patient experienced central nervous system leukemia (CNSL). Concurrent differentiation syndrome, white blood cell count, prothrombin time and D-dimer were related to death. Although the ED rate among APL patients with early ICH was high, patients with early ICH had a favorable outcome after surviving through induction therapy. CNSL was rare despite a history of ICH during induction therapy. Compared with APL patients without ICH, it seems unnecessary to administer additional measures to prevent CNSL for this subpopulation in the era of all-trans retinoic acid and arsenic trioxide, but this needs further validation in prospective trials.

Oral arsenic trioxide for treating acute promyelocytic leukaemia: Implications for its worldwide epidemiology and beyond

This account describes how orally administered Arsenic-trioxide (ATO) therapy influences the epidemiology of acute promyelocytic leukaemia (APL), and how the experience that ensued may expand the indications for oral ATO as a treatment for diseases/disorders other than APL. Over the last two decades, experience with APL patients in Hong Kong treated with an oral regimen comprising ATO, all-trans retinoic acid (ATRA), and ascorbic acid (also known as "AAA") has confirmed a dramatic improvement in overall survival. Over that period, there has been an estimated 60-fold increase in the prevalence of APL (proportion of surviving APL patients in the population on December 31 including those deemed to be 'cured'). In contrast to regimens entailing intravenous (IV) ATO, the consequential therapeutic benefits of using oral ATO have been achieved with much less patient inconvenience and quality of life disruption, reduced burdens on health care facilities (hospitalisations and staff involvement), and much enhanced affordability (retail drug & other cost reductions). Numerous experimental and a few clinical studies suggest that ATO may also have a therapeutic role in many other diseases/disorders. Several such diseases (e.g. autoimmune disorders & idiopathic pulmonary fibrosis) are far more prevalent than APL, which means that very large numbers of patients may potentially benefit from ATO treatment, even if its efficacy is limited to selected populations with these diseases. The known safety of oral ATO and its advantages over repeated long-term IV delivery suggests that this route be used in future clinical studies of its possible role in treating such patients. If the clinical utility of oral ATO treatment is validated for patients enduring any such non-APL diseases, very large numbers of patients may stand to benefit.

Predictors of early death and clinical features in newly diagnosed patients with low-intermediate risk acute promyelocytic leukemia

Background

Although most acute promyelocytic leukemia(APL) with low-intermediate risk could survive the induction treatment, early death still a big problem to have effects on overall survival in real world.This study aimed to analyze the clinical characteristics and possible predictors of early death in newly diagnosed patients with low-intermediate-risk acute promyelocytic leukemia.

Methods

Sixty patients with newly diagnosed low/intermediate-risk APL admitted to Mianyang Central Hospital from January 2013 to December 2021 were retrospectively analyzed.

Results

Sixty patients with a median age of 46 years (range, 17-75 years) were included. Fourteen patients (23.3%) were in low-risk group, and 46 patients (76.7%) were in intermediate-risk group. Fourteen patients (23.3%) died during induction treatment. Five patients died of hemorrhage, 5 of severe infection and 4 of differentiation syndrome. Multivariate analysis showed that HGB <65g/L at diagnosis (OR=38.474, 95%CI: 2.648~558.923, P=0.008) during induction treatment was an independent risk factors for early death in low- intermediate risk APL patients. In survival group, all patients achieved complete remission, the time to achieve remission was 25.87 ± 5.02 days, the average ATO dosage was 0.16 ± 0.03 mg/kg/day. In univariate analysis, there was no statistically significant difference in time span for remission when ATO dosage was in the 0.11~0.16mg/kg/day range. Compared with patients with low-risk APL, those with intermediate-risk APL had higher white blood cell counts (at diagnosis, day 3, day 5 and peak), higher level of lactate dehydrogenase, higher percentage of bone marrow promyelocytes, more platelet transfusions during treatment, and more early deaths (P<0.05). The overall survival of intermediate-risk APL patients seemed worse than those with low-risk APL (χ=5.033, P =0.025).

Conclusions

In patients with low-intermediate risk APL, HGB <65g/L at diagnosis was an independent risk factors for early death. Remission could still be achieved at low-dose ATO without affecting the required time for low-intermediate risk APL patients. Differences in clinical characteristics were found between low-risk and intermediate-risk APL. The intermediate-risk group had higher early mortality risk than the low-risk group.

Acute promyelocytic leukemia: Immunophenotype and differential diagnosis by flow cytometry

BACKGROUND

Prompt diagnosis of acute promyelocytic leukemia (APL) is critical for patient care. In this study, we aimed to characterize the immunophenotype of APL and explore immunophenotypic difference between APL and its mimics using flow cytometric analysis.

METHODS

Eighty-five cases were collected, including 47 APL, 26 NPM1-mutated acute myeloid leukemia (AML) and 12 KMT2A-rearranged AML with an APL-like immunophenotype. Immunophenotypes were analyzed using flow cytometric analysis.

RESULTS

APL showed four distinct patterns (designated a-d) based on CD45/SSC plots. Blasts in patterns a-c showed high side scatter, whereas blasts in pattern d had low side scatter and were located in the traditional blast gate. Compared with patterns a-c, pattern d of APL (APL-D) was more often positive for CD2 (p = 0.0005) and CD34 (p = 0.0002) in blasts. All NPM1-mutated AML and KMT2A-rearranged AML cases with an APL-like immunophenotype had blasts in the traditional blast gate on CD45/SSC, mimicking APL-D. In comparison, uniform CD13 and positive CD64 were seen in 100% (n = 13) APL-D cases and in only 2 of 26 (8%) NPM1-mutated AML cases (p < 0.0001). In addition, APL-D cases were more likely to be positive for CD2 and/or CD34 than NPM1-mutated AML (p < 0.0001 and p = 0.0007, respectively). In comparison with APL-D, KMT2A-rearranged AML cases were less often positive for myeloperoxidase (MPO) (p = 0.001), with none being strongly positive. Similar to NPM1-mutated AML and different from APL-D, KMT2A-rearranged AML cases were rarely positive for CD34 and all negative for CD2.

CONCLUSIONS

APL and its immunophenotypic mimics share some immunophenotypic similarities but can be distinguished by CD2, CD13, CD34, CD64, and MPO.

CD44-fibrinogen binding promotes bleeding in acute promyelocytic leukemia by in situ fibrin(ogen) deposition

Early haemorrhagic death is still the main obstacle for the successful treatment of acute promyelocytic leukaemia (APL). However, the mechanisms underlying haemostatic perturbations in APL have not been fully elucidated. Here, we report that CD44 on the membrane of APL blasts and NB4 cells ligated bound fibrinogen, resulting in in situ deposition of fibrin and abnormal fibrin distribution. Clots formed by leukaemic cells in response to CD44 and fibrinogen interaction exhibited low permeability and resistance to fibrinolysis. Using flow cytometry and confocal microscopy, we found that CD44 was also involved in platelet and leukaemic cell adhesion. CD44 bound activated platelets but not resting platelets through interaction with P-selectin. APL cell-coated fibrinogen-activated platelets directly induce enhanced procoagulant activity of platelets. In vivo studies revealed that CD44 knockdown shortened bleeding time, increased the level of fibrinogen, and elevated the number of platelets by approximately 2-fold in an APL mouse model. Moreover, CD44 expression on leukaemic cells in an APL mouse model was not only associated with bleeding complications but was also related to the wound healing process and the survival time of APL mice. Collectively, our results suggest that CD44 may be a potential intervention target for preventing bleeding complications in APL.

Analysis of risk factors for early death in patients with acute promyelocytic leukaemia treated with arsenic trioxide

To date, no specific studies have evaluated early death (ED) in patients with acute promyelocytic leukaemia (APL) homogeneously treated with arsenic trioxide induction therapy and investigated according to the white blood cell (WBC) count at onset. Such patients were retrospectively analysed in this study, including 314 patients with a WBC count ≤ 10 × 10⁹/L (standard-risk (SR) group) and 144 with a WBC count > 10 × 10⁹/L (high-risk (HR) group). The baseline clinical characteristics and risk factors for ED were compared between the two groups. The incidence of fibrinogen < 1.0 g/L and elevated serum uric acid, aspartate aminotransferase and creatinine levels were higher in the HR group than in the SR group (P = 0.001; P < 0.001; P < 0.001; P = 0.044, respectively). The ED rate was significantly higher in the HR group than in the SR group (29.17% vs. 10.83%, P < 0.001). The main cause of ED was bleeding, followed by infection and differentiation syndrome (DS) in the HR group, while it was bleeding, followed by DS and infection in the SR group. Male sex, age > 50 years old, and fibrinogen < 1.0 g/L were independent risk factors for ED in the SR group. Increased serum creatinine levels, decreased albumin levels, and fibrinogen < 1.0 g/L were independent risk factors for ED in the HR group. Overall, the incidence of ED was higher in the HR group, and the baseline clinical characteristics, causes, times, and predictors of ED in the HR group differed from those in the SR group.

Predictive factors for differentiating thrombohemorrhagic disorders in high-risk acute promyelocytic leukemia

INTRODUCTION

Acute promyelocytic leukemia (APL) is often accompanied by potentially fatal coagulopathy, especially in high-risk APL. Bleeding, particularly severe bleeding is the leading cause of early death (ED). Meanwhile, thrombosis, the other major coagulopathic complication, is being increasingly recognized. However, predictors of thrombohemorrhagic disorders are still not well investigated.

MATERIALS AND METHODS

In this study, we retrospectively studied 83 patients with high-risk APL and categorized them into severe bleeding, thrombosis and no evident events groups.

RESULTS

Severe bleeding was observed in 15 patients, nearly half of whom died of hemorrhage, while thrombosis was observed in 12 patients. Risk factor analysis showed that high WBC (>58.76 × 10⁹/L) (p = 0.001) and prolonged PT (>17.7 s) (p = 0.015) could be independent predictors for severe bleeding, while high WBC/D-dimer>5.12 (p = 0.002) and low D-dimer/FIB<5.14 (p = 0.03) could be independent predictors for thrombosis in high-risk APL patients. Moreover, there are significant differences in WBC/D-dimer and D-dimer/FIB between DIC and Non-DIC groups (p < 0.001). Notably, we found that the WBC/D-dimer was dramatically higher in the thrombotic group than in the other two groups at the time of admission or during the first week of induction therapy.

CONCLUSIONS

High WBC and prolonged PT could predict severe bleeding in high-risk APL patients, while high WBC/D-dimer and low D-dimer/FIB could be independent predictors for thrombosis. For high-risk APL, WBC/D-dimer and D-dimer/FIB are also beneficial in the diagnosis of DIC. WBC/D-dimer might help early identification of thrombosis at the time of admission or during the first week of induction therapy.