Rapid and reliable confirmation of acute promyelocytic leukemia by immunofluorescence staining with an antipromyelocytic leukemia antibody: the M. D. Anderson Cancer Center experience of 349 patients

Deep learning for diagnosis of acute promyelocytic leukemia via recognition of genomically imprinted morphologic features

Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia (AML), classified by a translocation between chromosomes 15 and 17 [t(15;17)], that is considered a true oncologic emergency though appropriate therapy is considered curative. Therapy is often initiated on clinical suspicion, informed by both clinical presentation as well as direct visualization of the peripheral smear. We hypothesized that genomic imprinting of morphologic features learned by deep learning pattern recognition would have greater discriminatory power and consistency compared to humans, thereby facilitating identification of t(15;17) positive APL. By applying both cell-level and patient-level classification linked to t(15;17) PML/RARA ground-truth, we demonstrate that deep learning is capable of distinguishing APL in both discovery and prospective independent cohort of patients. Furthermore, we extract learned information from the trained network to identify previously undescribed morphological features of APL. The deep learning method we describe herein potentially allows a rapid, explainable, and accurate physician-aid for diagnosing APL at the time of presentation in any resource-poor or -rich medical setting given the universally available peripheral smear.

Microfluidic-Based Detection of AML-Specific Biomarkers Using the Example of Promyelocyte Leukemia

A microfluidic assay for the detection of promyelocytic leukemia (PML)-retinoic acid receptor α (RARα) fusion protein was developed. This microfluidic-based system can be used for rapid personalized differential diagnosis of acute promyelocyte leukemia (APL) with the aim of early initiation of individualized therapy. The fusion protein PML-RARα occurs in 95% of acute promyelocytic leukemia cases and is considered as diagnostically relevant. The fusion protein is formed as a result of translocation t(15,17) and is detected in the laboratory by fluorescence in situ hybridization (FISH) or reverse transcriptase polymerase chain reaction (RT-PCR). Diagnostic methods require many laboratory steps with specialized staff. The developed microfluidic assay includes a sandwich enzyme-linked immunosorbent assay (ELISA) system for PML-RARα on surface of magnetic microparticles in a microfluidic chip. A rapid detection of PML-RARα in cell lysates is achieved in less than one hour. A biotinylated PML-antibody on the surface of magnetic streptavidin coated microparticles is used as capture antibody. The bound translocation product is detected by a RARα antibody conjugated with horseradish peroxidase and the substrate QuantaRed. The analysis is performed in microfluidic channels which involves automated liquid processing with stringent washing and short incubation times. The results of the developed assay show that cell lysates of PML-RARα-positive cells (NB-4) can be clearly distinguished from PML-RARα-negative cells (HL-60, MV4-11).

Liquid biopsy technologies for hematological diseases

Since the discovery of circulating tumor cells in 1869, technological advances in studying circulating biomarkers from patients' blood have made the diagnosis of nonhematologic cancers less invasive. Technological advances in the detection and analysis of biomarkers provide new opportunities for the characterization of other disease types. When compared with traditional biopsies, liquid biopsy markers, such as exfoliated bladder cancer cells, circulating cell-free DNA (cfDNA), and extracellular vesicles (EV), are considered more convenient than conventional biopsies. Liquid biopsy markers undoubtedly have the potential to influence disease management and treatment dynamics. Our main focuses of this review will be the cell-based, gene-based, and protein-based key liquid biopsy markers (including EV and cfDNA) in disease detection, and discuss the research progress of these biomarkers used in conjunction with liquid biopsy. First, we highlighted the key technologies that have been broadly adopted used in hematological diseases. Second, we introduced the latest technological developments for the specific detection of cardiovascular disease, leukemia, and coronavirus disease. Finally, we concluded with perspectives on these research areas, focusing on the role of microfluidic technology and artificial intelligence in point-of-care medical applications. We believe that the noninvasive capabilities of these technologies have great potential in the development of diagnostics and can influence treatment options, thereby advancing precision disease management.

Acute promyelocytic leukemia in a patient with chronic lymphocytic leukemia-A case report

Chronic lymphocytic leukemia (CLL) is known to be associated rarely with myeloid malignancies such as acute myelogenous leukemia. In this article, we report an extremely rare occurrence of acute promyelocytic leukemia in a patient with CLL. A 71-year-old man first presented to our clinic with a diagnosis of CLL and worsening motor neuropathy symptoms. It was suspected that his CLL might be contributing to the neuropathy as a paraneoplastic syndrome, and he was treated with rituximab monotherapy in weekly doses for the 1st month and monthly treatments thereafter. By the end of his sixth monthly course of rituximab, the patient noted significant improvement in neuropathy symptoms but reported experiencing a new-onset worsening fatigue. He had new-onset cytopenias (white blood cells 1.6k/µL, hemoglobin 11.7g/dL, and platelet count 77k/µL). A bone marrow examination was performed; it showed a high percentage of progranulocytes (21%), which stained positive for myeloperoxidase (MPO) and demonstrated a fine granular pattern on the promyelocytic leukemia (PML) oncogenic domain immunofluorescence test. The diagnosis of acute promyelocytic leukemia was confirmed by fluorescence in situ hybridization, which showed a PML/RARα rearrangement in 46% of interphases. Flow cytometry was consistent with immunophenotype of acute promyelocytic leukemia and minimal residual CLL (0.07%). The patient was started promptly on all-trans-retinoic acid and arsenic trioxide induction regimen. Molecular remission was achieved after the first consolidation cycle. The patient is currently past his fourth consolidation cycle of all-trans-retinoic acid/arsenic trioxide and continues to be in complete remission. Our case illustrates that it is important for the physicians to be aware of coexistent hematologic and solid tumor malignancies in CLL, and maintain a low threshold for diagnostic testing based on grounds of low clinical suspicion.

Early treatment of acute promyelocytic leukaemia is accurately guided by the PML protein localisation pattern: real-life experience from a tertiary New Zealand centre

Current guidelines recommend that a rapid test be used to assist diagnosis of acute promyelocytic leukaemia (APL), but the choice of an assay is discretionary. PML immunofluorescence (PML IF) identifies the microparticulate pattern of the PML protein localisation, highly specific for APL. The aim of this study was to evaluate clinical utility of PML IF in a real-life setting based on a retrospective records review for all patients who had PML IF performed in our centre between 2000 and 2017. Final analysis included 151 patients, 70 of whom had APL. PML IF was reported on average 3 days faster than cytogenetics. Compared with genetic results, PML IF showed sensitivity of 96% and specificity of 100%. PML IF accurately predicted APL in four APL cases with cryptic karyotype/FISH and excluded APL in 98% cases tested based on the suspicious immunophenotype alone, 21/28 of whom had mutated NPM1. Results of PML IF influenced decision to start ATRA in 25 (36%) APL patients and led to its termination in six non-APL patients. In conclusion, PML IF is a fast and reliable test that facilitates accurate treatment decisions when APL is suspected. This performance of PML IF remains hard to match in a real-life setting.

Initial Diagnostic Workup of Acute Leukemia: Guideline From the College of American Pathologists and the American Society of Hematology

CONTEXT

- A complete diagnosis of acute leukemia requires knowledge of clinical information combined with morphologic evaluation, immunophenotyping and karyotype analysis, and often, molecular genetic testing. Although many aspects of the workup for acute leukemia are well accepted, few guidelines have addressed the different aspects of the diagnostic evaluation of samples from patients suspected to have acute leukemia.

OBJECTIVE

- To develop a guideline for treating physicians and pathologists involved in the diagnostic and prognostic evaluation of new acute leukemia samples, including acute lymphoblastic leukemia, acute myeloid leukemia, and acute leukemias of ambiguous lineage.

DESIGN

- The College of American Pathologists and the American Society of Hematology convened a panel of experts in hematology and hematopathology to develop recommendations. A systematic evidence review was conducted to address 6 key questions. Recommendations were derived from strength of evidence, feedback received during the public comment period, and expert panel consensus.

RESULTS

- Twenty-seven guideline statements were established, which ranged from recommendations on what clinical and laboratory information should be available as part of the diagnostic and prognostic evaluation of acute leukemia samples to what types of testing should be performed routinely, with recommendations on where such testing should be performed and how the results should be reported.

CONCLUSIONS

- The guideline provides a framework for the multiple steps, including laboratory testing, in the evaluation of acute leukemia samples. Some aspects of the guideline, especially molecular genetic testing in acute leukemia, are rapidly changing with new supportive literature, which will require on-going updates for the guideline to remain relevant.

Treating acute promyelocytic leukaemia in Latin America: lessons from the International Consortium on Acute Leukaemia experience

The Latin Americas and Caribbean are regions where social exclusion and inequality persist as the main obstacles to human development and improvement of health conditions, despite economic growth and social development. These countries need to establish international collaborations with the goal of improving health conditions. In this scenario Acute Promyelocytic Leukaemia (APL), a disease with a high cure rate in developed countries and high prevalence in young patients, offers an ideal opportunity to implement measures with educational and cooperative scope. We discuss the experience of Latin America and the Caribbean through a common network, the International Consortium on Acute Promyelocytic Leukaemia (IC-APL).

Genetic Testing in Acute Myeloid Leukemia and Myelodysplastic Syndromes

Cytogenetic analysis of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) is essential for disease diagnosis, classification, prognostic stratification, and treatment guidance. Molecular genetic analysis of CEBPA, NPM1, and FLT3 is already standard of care in patients with AML, and mutations in several additional genes are assuming increasing importance. Mutational analysis of certain genes, such as SF3B1, is also becoming an important tool to distinguish subsets of MDS that have different biologic behaviors. It is still uncertain how to optimally combine karyotype with mutation data in diagnosis and risk-stratification of AML and MDS, particularly in cases with multiple mutations and/or several mutationally distinct subclones.

Current management of newly diagnosed acute promyelocytic leukemia

The management of acute promyelocytic leukemia (APL) has considerably evolved during the past two decades. The advent of all-trans retinoic acid (ATRA) and its inclusion in combinatorial regimens with anthracycline chemotherapy has provided cure rates exceeding 80%; however, this widely adopted approach also conveys significant toxicity including severe myelosuppression and rare occurrence of secondary leukemias. More recently, the advent of arsenic trioxide (ATO) and its use in association with ATRA with or without chemotherapy has further improved patient outcome by allowing to minimize the intensity of chemotherapy, thus reducing serious toxicity while maintaining high anti-leukemic efficacy. The advantage of ATRA-ATO over ATRA chemotherapy has been recently demonstrated in two large randomized trials and this option has now become the new standard of care in low-risk (i.e. non-hyperleukocytic) patients. In light of its rarity, abrupt onset and high risk of early death and due to specific treatment requirements, APL remains a challenging condition that needs to be managed in highly experienced centers. We review here the results of large clinical studies conducted in newly diagnosed APL as well as the recommendations for appropriate diagnosis, prevention and management of the main complications associated with modern treatment of the disease.

Identification of a novel fusion gene, IRF2BP2-RARA, in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is characterized by the fusion of retinoic acid receptor alpha (RARA) with promyelocytic leukemia (PML) or, rarely, other gene partners. This report presents a patient with APL with a novel fusion between RARA and the interferon regulatory factor 2 binding protein 2 (IRF2BP2) genes. A bone marrow examination in a 19-year-old woman who presented with ecchymoses and epistaxis showed morphologic and immunophenotypic features consistent with APL. PML oncogenic domain antibody was positive. Results of fluorescence in situ hybridization, conventional cytogenetics, reverse transcription-polymerase chain reaction (RT-PCR), and oligonucleotide microarray for PML-RARA and common APL variant translocations were negative. Next-generation RNA-sequencing analysis followed by RT-PCR and direct sequencing revealed distinct breakpoints within IRF2BP2 exon 2 and RARA intron 2. The patient received all-trans retinoic acid, arsenic, and gemtuzumab ozogamicin, and achieved complete remission. However, the disease relapsed 10 months later, 2 months after consolidation therapy. This is the first report showing involvement of IRF2BP2 in APL, and it expands the list of novel RARA partners identified in APL.

Immunostaining for rapid diagnosis of acute promyelocytic leukemia with the tetramethylrhodamine-5-isothiocyanate-conjugated anti-promyelocytic leukemia monoclonal antibody PG-M3

CONTEXT

Anti-promyelocytic leukemia (PML) immunofluorescence staining is a known diagnostic tool for rapid diagnosis of acute promyelocytic leukemia (APL).

OBJECTIVE

We describe our methods using the recently developed, commercially available, tetramethylrhodamine-5-isothiocyanate-labeled PG-M3 anti-PML antibody for APL testing.

DESIGN

Immunofluorescence staining with the tetramethylrhodamine-5-isothiocyanate-labeled PG-M3 antibody was used to detect PML-RARA in bone marrow aspirate and/or peripheral blood smears from 30 patients with acute leukemia. The results were compared with those of concurrent testing with our in-house polyclonal anti-PML antibody and with established tests.

RESULTS

All APL cases showed a positive (fine/microgranular) immunofluorescence staining pattern, whereas non-APL cases showed a negative (chunky/macrogranular) pattern. These results, which were available within 2 hours, were validated by testing with the polyclonal anti-PML antibody and with established cytogenetic and molecular testing methods.

CONCLUSIONS

We validated the utility of the tetramethylrhodamine-5-isothiocyanate-labeled anti-PML antibody PG-M3 for the diagnosis of APL. Our results indicate that immunofluorescence staining with this antibody is a rapid and reliable method for the diagnosis of APL.

Improving acute promyelocytic leukemia (APL) outcome in developing countries through networking, results of the International Consortium on APL

For patients in developing countries with APL, a clinical network of institutions made it possible to reduce significantly the early mortality and improve the OS.

Molecular basis for the diagnosis and treatment of acute promyelocytic leukemia

Acute promyelocytic leukemia is characterized by gene rearrangements that always involve the retinoic acid receptor alpha on chromosome 15. In the majority of patients t(15;17) is detected, which generates the promyelocytic leukemia gene/retinoic acid receptor alpha rearrangement. This rearrangement interacts with several proteins, including the native promyelocytic leukemia gene, thus causing its delocalization from the nuclear bodies, impairing its function. The immunofluorescence staining technique using the anti-PML antibody may be used to provide a rapid diagnosis and to immediately start therapy using all-trans retinoic acid. The experience of the International Consortium on Acute Promyelocytic Leukemia has demonstrated that early mortality was significantly reduced by adopting the immunofluorescence technique. All-trans retinoic acid combined with chemotherapy is the standard therapy; this promotes complete remission rates greater than 90% and cure rates of nearly 80%. However, early mortality is still an important limitation and hematologists must be aware of the importance of treating newly diagnosed acute promyelocytic leukemia as a medical emergency.

Management of AML: who do we really cure?

Most clinicians caring for patients with AML do not use the word "cure" casually, since for many patients diagnosed with AML, a state of cure or even of long term survival remains elusive. Analysis of prognostic factors may aid in defining the chance for cure in various AML subtypes, and improvements are required at all stages of AML treatment if cure is to be realized in a higher proportion of patients. In order to improve outcome, requirements will include targeting the mutation responsible for the leukemia emergence, suppressing the stem or progenitor cell which acquires the mutation, and the capability to deliver therapy to patients who themselves have adverse co-morbidities.

Managing acute promyelocytic leukemia without conventional chemotherapy: is it possible?

The introduction of all-trans retinoic acid in 1985 combined with anthracycline-based chemotherapy has revolutionized the prognosis of acute promyelocytic leukemia (APL) with current complete response rates of more than 90% and cure rates of approximately 80%. The subsequent advent of arsenic trioxide in 1994 marked an additional milestone in APL treatment and has inspired the design of rationally targeted, chemotherapy-free front-line treatment regimens without compromising the excellent outcome achieved by anthracycline-containing protocols. APL is, therefore, a unique subtype of acute myeloid leukemia potentially curable with targeted therapies without any exposure to conventional DNA-damaging chemotherapy. Cure rates of APL can be further increased by implementing management strategies to reduce early hemorrhagic deaths, which remain the major cause of treatment failure with the current therapy.

Curing all patients with acute promyelocytic leukemia: are we there yet?

The introduction of all-trans retinoic acid to anthracycline-based chemotherapy has revolutionized the prognosis of patients with acute promyelocytic leukemia (APL). The introduction of arsenic trioxide enabled the therapeutic approach of rationally targeted frontline protocols with minimal or no traditional cytotoxic chemotherapy and without compromise of previously established outstanding outcomes with anthracycline-based regimens. Although most of the current investigative efforts in APL are focused on developing potentially curative therapy without the exposure to toxicities and risks of DNA-disrupting agents, the cure rate can further be increased by implementing meticulous supportive care strategies that counter early coagulopathy-related deaths.

Class II-associated invariant chain peptide expression represents a novel parameter for flow cytometric detection of acute promyelocytic leukemia

Because of severe bleeding complications, patients with acute promyelocytic leukemia (APL) have to be treated with all-trans retinoic acid immediately following diagnosis. In addition to morphology, flow cytometry contributes to a rapid detection of APL according to phenotypic characteristics of leukemic cells. In some patients, these analyses are inconclusive or even contradictory to diagnosis. Previously, we showed the clinical and functional impact of class II-associated invariant chain peptide (CLIP) in acute myeloid leukemia (AML). This study focuses on the analysis of CLIP expression on leukemic cells to characterize HLA-DR-negative AML, including APL. We demonstrate exclusive and significant CLIP expression in all cases of typical and variant APL, as compared to other HLA-DR-negative non-APL-type AML. CLIP appears to be a highly sensitive and specific flow cytometric marker, resolving discrepant identification of both genetic subgroups. Our findings show the additive value of CLIP analysis for a fast and unequivocal recognition of APL by flow cytometry in conjunction with morphology.

Early death rate in acute promyelocytic leukemia remains high despite all-trans retinoic acid

The incidence of early death in a large population of unselected patients with acute promyelocytic leukemia (APL) remains unknown because of the paucity of outcome data available for patients treated outside of clinical trials. We undertook an epidemiologic study to estimate the true rate of early death with data from the Surveillance, Epidemiology, and End Results (SEER) program. A total of 1400 patients with a diagnosis of APL between 1992 and 2007 were identified. The overall early death rate was 17.3%, and only a modest change in early death rate was observed over time. The early death rate was significantly higher in patients aged ≥ 55 years (24.2%; P < .0001). The 3-year survival improved from 54.6% to 70.1% over the study period but was significantly lower in patients aged ≥ 55 years (46.4%; P < .0001). This study shows that the early death rate remains high despite the wide availability of all-trans retinoic acid and appears significantly higher than commonly reported in multicenter clinical trials. These data highlight a need to educate health care providers across a wide range of medical fields, who may be the first to evaluate patients with APL, to have a major effect on early death and the cure rate of APL.

Treatment of acute promyelocytic leukemia for older patients

Acute promyelocytic leukemia (APL) represents a remarkable disease in which leukemogenesis is driven by the PML-RARα oncogene and for which targeted treatment with all-trans retinoic acid (ATRA)-based therapy allows substantial chance of cure. APL is seen in a small subset of older patients, with age representing one of the most important prognostic factors for outcome of treatment. Unlike other acute leukemias, the inferior outcomes for APL in older patients relates less to changes in disease biology and more to the increased toxicity of ATRA and the chemotherapy combination regimens used to induce hematologic and molecular responses. Risk-adapted strategies that use less-toxic agents, such as arsenic trioxide, allow treatment of older patients, with greater efficiency and better chances of cure.