The Coagulopathy of Acute Promyelocytic Leukemia: An Updated Review of Pathophysiology, Risk Stratification, and Clinical Management

RAPID-CRISPR: highly sensitive diagnostic assay for detection of PML::RARA isoforms in acute promyelocytic leukemia

ABSTRACT

Acute promyelocytic leukemia (APL), distinguished by the presence of PML::RARA fusion transcript, is a medical emergency because of its high early death rate, which is preventable when diagnosed early. Current diagnostic methods are precise and reliable but are time intensive, require sophisticated instruments, and analytical expertise. This study has redefined APL identification by CRISPR system (RAPID-CRISPR) to rapidly (<3 hours) detect PML::RARA. APL cell lines (NB4 and UF-1) and bone marrow/peripheral blood samples from 74 patients with APL (66/8, retrospective/prospective) and 48 controls were included in the study. We used a DETECTR (DNA endonuclease-targeted CRISPR transreporter) assay to identify the bcr1, bcr2, and bcr3 PML::RARA isoforms. To ensure high specificity, we used PML::RARA-specific loop-mediated isothermal amplification (LAMP) primers, synthetic protospacer-adjacent motif sites, and isoform-specific CRISPR RNAs. RAPID-CRISPR recognized APL with 100% sensitivity and 100% specificity in an ambispective cohort of patient samples. Furthermore, our blinded validation approach to detect PML::RARA in an unbiased manner provides an additional layer in the diagnostic precision of APL. RAPID-CRISPR demonstrated superior sensitivity, detecting as few as 1 copy of PML::RARA compared with 10 copies by the gold-standard reverse transcriptase qualitative and quantitative polymerase chain reaction. The nucleic acid extraction-free protocol combined with the 1-step reverse transcriptase LAMP-based DETECTR followed by lateral flow readout makes the RAPID-CRISPR assay suitable for diagnosing APL in point-of-care settings. This simple, cost-effective tool, with its easy-to-read format, is particularly valuable in underresourced regions. The assay facilitates timely diagnosis and prompt administration of lifesaving therapies such as all-trans retinoic acid and arsenic trioxide in APL.

Acute Promyelocytic Leukemia in the Real World: Understanding Outcome Differences and How We Can Improve Them

The advent of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has revolutionized the treatment of acute promyelocytic leukemia (APL), resulting in excellent rates of remission and long-term survival. However, real-world outcomes often fall short of those observed in clinical trials due to various factors related to patient demographics and clinical practices. This review examines APL treatment outcomes in real-world settings and highlights the phenomenon of APL clusters. Clinical trials frequently exclude older patients and individuals with significant comorbidities, yet these groups represent a substantial portion of patients in clinical practice. Early mortality remains high in real-world settings, compounded by delayed diagnosis and treatment initiation, as well as the inexperience of some community providers and limited resources of their centers in managing APL and its associated complications. High rates of disease and induction-related complications further exacerbate early mortality. Continuous education and collaboration between community healthcare centers and expert institutions are essential, and international partnerships between resource-limited settings and expert centers can improve global APL outcomes. Ongoing monitoring for measurable residual disease (MRD) recurrence and long-term treatment toxicity, coupled with comprehensive patient evaluations, and experienced management, can enhance long-term outcomes. The clustered incidence of APL, while frequently reported, remains poorly understood. Regular reporting of these clusters could provide valuable insights into disease pathology and aid in developing predictive models for APL incidence, which would guide future resource allocation.

Challenging Situations in the Treatment of Cancer-Associated Thrombosis

Cancer-associated thrombosis (CAT) is a common clinical problem in the treatment of cancer patients posing some unique challenges. These include the need to balance between the risk of recurrent thromboembolic events and bleeding complications in the individual cancer patient. A frequently encountered dilemma is the need for long-term anticoagulation in the setting of active malignancy. Until now, optimal duration, intensity, and type of anticoagulation in cancer patients remain an area of ongoing debate. In this case-based review, we present several challenging clinical scenarios and provide guidance on management. For optimal treatment results, CAT generally requires a multidisciplinary approach including specialists for thrombosis and hemostasis as well as hematology and oncology. Individual patient preferences should always be taken into account, especially in clinical situations with weak treatment evidence.

Bridging the gap: understanding contemporary autopsies in acute leukemia by comparing ante-mortem and post-mortem profiles

This study investigates acute myeloid leukemia/lymphoblastic leukemia (AML/ALL) through a 14-year analysis (2009-2022) of 46 autopsied cases (age >12 years). B-ALL was the dominant subtype (34.8%). Liver and spleen were the common sites of active leukemia (63% cases). Symptoms like dyspnea and altered sensorium associated significantly with heart (p = .031) and brain leukostasis (p = .006). Measurable residual disease (MRD) negativity correlated with disease-free status outside the bone marrow, while MRD-positive cases displayed leukemic infiltrates. Infections were identified in 23 autopsied cases, notably linked to post-induction and post-transplant fatalities. Surprisingly, 18 of these 23 cases had unexpected infections mainly fungal (13 cases) with Aspergillus species as the most common. Diagnostic discrepancies were identified in 48% of cases. Malignant infiltration (46%) and infections (25%) were the leading causes of death. This research sheds light on leukemia in extra-medullary tissues, uncovers novel clinical-pathological associations, and highlights overlooked therapy side effects, offering insights for future case management.

MRD in Acute Leukemias: Lessons Learned from Acute Promyelocytic Leukemia

Introduction: Advances in molecular biology, polymerase chain reaction (PCR), and next-generation sequencing (NGS) have transformed the concept of minimal residual disease (MRD) from a philosophical idea into a measurable reality. Current Treatment Paradigms and Lessons Learned from APL: Acute promyelocytic leukemia (APL) leads the way in this transformation, initially using PCR to detect MRD in patients in remission, and more recently, aiming to eliminate it entirely with modern treatment strategies. Along the way, we have gained valuable insights that, when applied to other forms of acute leukemia, hold the potential to significantly improve the outcomes of these challenging diseases. Does the BM Microenvironment Play a Role in MRD?: In this review, we explore the current use of MRD in the management of acute leukemia and delve into the biological processes that contribute to MRD persistence, including its overlap with leukemia stem cells and the role of the bone marrow microenvironment.

Clinical characteristics of acute myeloid leukaemia patients with a large number of azurophilic granules: A single-centre retrospective study

Large amounts of azurophilic granules are considered to be a morphological feature of acute promyelocytic leukaemia (APL). However, a small percentage of acute myeloid leukaemia (AML) patients also have a large number of azurophilic granules. A large cohort of 3210 AML patients in our hospital was screened to identify AML patients who had a large number of azurophilic granules. The clinical parameters of these patients were collected and compared with typical AML patients (control Group 1) and APL patients (control Group 2). The incidence of AML with a large number of azurophilic granules was 1.26%. The fibrinogen and D-dimer levels of patients in the study group were more similar to those of patients in control Group 2, as was the incidence of bleeding events. Additionally, patients in the study group had higher FLT3-ITD and NPM1 mutation rates than patients in control Group 1. Finally, patients in the study group had a higher 30-day mortality rate than those in control Group 2 (24.2% vs. 9.09%) and showed a higher 30-day mortality trend than those in control Group 1. Therefore, we should pay more attention to the prevention of coagulation dysfunction and bleeding events for these patients.

Disseminated Intravascular Coagulation in Acute Promyelocytic Leukemia Patients: A Retrospective Analysis of Outcomes and Healthcare Burden in US Hospitals

Objective

Acute promyelocytic leukemia (APL) is associated with an elevated risk of developing disseminated intravascular coagulation (DIC). The purpose of this study was to assess the outcomes of hospitalizations related to DIC in APL and their impact on healthcare.

Materials and Methods

This study entailed a cross-sectional and retrospective analysis of the US National Inpatient Sample database. We identified adults with APL and categorized them into groups of patients with and without DIC. Our focus areas included in-hospital mortality, length of stay, charges, and complications associated with DIC. Unadjusted odds ratios/coefficients were computed in univariate analysis, followed by adjusted odds ratios (aOR)/coefficients from multivariate analysis that accounted for confounding factors.

Results

Our analysis revealed that APL patients with DIC had a substantially higher aOR for mortality (aOR: 6.68, 95% confidence interval [CI]: 4.76-9.37, p<0.001) and a prolonged length of stay (coefficient: 10.28 days, 95% CI: 8.48-12.09, p<0.001) accompanied by notably elevated total hospital charges (coefficient: $215,512 [95% CI: 177,368-253,656], p<0.001), thereby emphasizing the reality of extended medical care and economic burden. The presence of DIC was associated with increased odds of sepsis, vasopressor support, pneumonia, acute respiratory failure, intubation/mechanical ventilation, and acute kidney injury, reflecting heightened vulnerability to these complications. Patients with DIC demonstrated significantly higher odds ratios for major bleeding, intracranial hemorrhage, gastrointestinal bleeding, red blood cell transfusion, platelet transfusion, fresh frozen plasma transfusion, and cryoprecipitate transfusion, highlighting the pronounced hematological risks posed by DIC.

Conclusion

This study has revealed the significant associations between DIC in APL and various outcomes, underscoring the clinical and economic implications of these conditions. The hematological risks further increase patients’ vulnerability to bleeding events and the need for transfusions.

Cancer-associated splanchnic vein thrombosis: Clinical implications and management considerations

Splanchnic vein thrombosis (SVT), a thrombosis which involves the portal, mesenteric, and splenic veins, and the Budd-Chiari syndrome, represents an uncommon type of venous thromboembolism (VTE). Like with deep vein thrombosis of the lower extremities and pulmonary embolism, ample evidence suggests a significant association between SVT and cancer, particularly intra-abdominal solid malignancies (e.g. hepatobiliary and pancreatic cancers) and myeloproliferative neoplasms (MPN). Clinical symptoms of SVT in cancer patients can be ambiguous, and frequently attributed to the primary cancer itself. Alternatively, SVT may be asymptomatic and detected incidentally during cancer staging or follow-up evaluations. SVT can also precede the diagnosis of cancer and has been associated with poorer outcomes in patients with liver or pancreatic cancers. Therefore, an unprovoked SVT warrants a thorough evaluation for an underlying malignancy or MPN. Cancer-associated SVT carries a high risk of VTE extension, recurrence and bleeding. Extended anticoagulant treatment is often required in the absence of a high bleeding risk. Guidelines suggest treatment with either low molecular weight heparin (LMWH) or direct oral anticoagulants (DOACs), although available data on the safety and effectiveness of DOACs in these patients is limited. This comprehensive review outlines the epidemiology, pathogenesis, risk factors, and diagnosis of cancer-associated SVT and underscores the importance of comprehensive patient evaluation and evidence-based management.

Thrombosis in Myeloid Malignancies: From CHIP to AML

The development of myeloid malignancies is a multi-step process starting from pre-malignant stages. Large-scale studies on clonal hematopoiesis of indeterminate potential (CHIP) identified this condition as a risk factor for developing hematologic malignancies, in particular myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). In parallel, CHIP was found to confer an enhanced thrombotic risk, in particular for cardiovascular diseases. In a similar fashion, in recent years, alongside their life-threatening features, increasing attention has been drawn toward thrombotic complications in myeloid malignancies. Thus, the purpose of this review is to gather a growing body of evidence on incidence, pathogenesis and clinical impact of thrombosis in myeloid malignancies at every step of malignant progression, from CHIP to AML.