Clinical significance of complex karyotype at diagnosis in pediatric and adult patients with de novo acute promyelocytic leukemia treated with ATRA and chemotherapy

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.

Acute promyelocytic leukemia with additional chromosome abnormalities in a patient positive for HIV: A case report and literature review

Acute promyelocytic leukemia (APL), especially cases of high-risk with complex chromosomes (CK), is rare in individuals infected with human immunodeficiency virus (HIV), making the establishment of therapeutic approaches challenging; often the treatment is individualized. This report describes a 49-year-old female patient with HIV who was diagnosed with high-risk APL with a new CK translocation and presents a literature review. At diagnosis, the patient presented with typical t(15;17)(q24;q21) with additional abnormalities, including add(5)(q15), add(5)(q31), add(7)(q11.2) and add(12) (p13). The results of acute myeloid leukemia mutation analysis suggested positivity for calreticulin and lysine methyltransferase 2C genes. The patient received all-trans retinoic acid combined with arsenic trioxide and chemotherapy, with morphologically complete remission after the first cycle of chemotherapy. The present report provided preliminary data for future clinical research.

Incidence, risk factors, and outcomes of second neoplasms in patients with acute promyelocytic leukemia: the PETHEMA-PALG experience

The most important challenges in acute promyelocytic leukemia (APL) is preventing early death and reducing long-term events, such as second neoplasms (s-NPLs). We performed a retrospective analysis of 2670 unselected APL patients, treated with PETHEMA "chemotherapy based" and "chemotherapy free" protocols. Only de novo APL patients who achieved complete remission (CR) and completed the three consolidation cycles were enrolled into the analysis. Out of 2670 APL patients, there were 118 (4.4%) who developed s-NPLs with the median latency period (between first CR and diagnosis of s-NPL) of 48.0 months (range 2.8-231.1): 43.3 (range: 2.8-113.9) for s-MDS/AML and 61.7 (range: 7.1-231.1) for solid tumour. The 5-year CI of all s-NPLs was of 4.43% and 10 years of 7.92%. Among s-NPLs, there were 58 cases of s-MDS/AML, 3 cases of other hematological neoplasms, 57 solid tumours and 1 non-identified neoplasm. The most frequent solid tumour was colorectal, lung and breast cancer. Overall, the 2-year OS from diagnosis of s-NPLs was 40.6%, with a median OS of 11.1 months. Multivariate analysis identified age of 35 years (hazard ratio = 0.2584; p < 0.0001) as an independent prognostic factor for s-NPLs. There were no significant differences in CI of s-NPLs at 5 years between chemotherapy-based vs chemotherapy-free regimens (hazard ratio = 1.09; p = 0.932). Larger series with longer follow-up are required to confirm the potential impact of ATO+ATRA regimens to reduce the incidence of s-NPLs after front-line therapy for APL.

Cytogenetics in the management of acute myeloid leukemia and histiocytic/dendritic cell neoplasms: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Genetic data are becoming increasingly essential in the management of hematological neoplasms as shown by two classifications published in 2022: the 5th edition of the World Health Organization Classification of Hematolymphoid Tumours and the International Consensus Classification of Myeloid Neoplasms and Acute Leukemias. Genetic data are particularly important for acute myeloid leukemias (AMLs) because their boundaries with myelodysplastic neoplasms seem to be gradually blurring. The first objective of this review is to present the latest updates on the most common cytogenetic abnormalities in AMLs while highlighting the pitfalls and difficulties that can be encountered in the event of cryptic or difficult-to-detect karyotype abnormalities. The second objective is to enhance the role of cytogenetics among all the new technologies available in 2023 for the diagnosis and management of AML.

Case Report: Co-existence of a novel EXOC4-TRHDE gene fusion with PML-RARA in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is a type of myeloid leukemia with a specific chromosomal translocation t(15;17)(q22; q12) forming the PML-RARA fusion gene. However, approximately one third of newly diagnosed patients with APL have additional chromosomal abnormalities. Here, we report a case of APL with co-existence of a novel translocation t(7;12)(q32;q13) involving an out-of-frame fusion between EXOC4 and TRHDE, together with PML-RARA. The patient achieved complete remission after treatment with conventional therapy with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). Although the causative link between EXOC4-TRHDE and PML-RARA has yet to be established, the patient had a good response to therapy, suggesting that the EXOC4-TRHDE fusion does not affect the efficacy of combined treatment with ATRA and ATO.

Acute promyelocytic leukemia masquerading as myeloid maturation arrest- A Case report

Acute promyelocytic leukemia (APL) is a medical emergency. The diagnosis of APL requires morphological examination, cytochemistry, immunophenotyping, and reverse transcriptase polymerase chain reaction (RT-PCR) for PML::RARA or its variants. However, due to the rapid development of complications, diagnosis often relies on morphology and cytochemistry for early treatment. Herein, we describe a 72-year-old gentleman who presented with pancytopenia diagnosed as acute promyelocytic leukemia with an unusual morphology. The bone marrow smear showed 80% myelocyte-like cells with prominent granules and maturation arrest, with an occasional neutrophil. On careful re-examination of the peripheral smear and bone marrow, an occasional poorly preserved cell with a bundle of Auer rods was identified. Cytochemistry for MPO was strongly positive in abnormal promyelocytes and flow cytometry showed positivity for MPO, CD13, CD33, and CD117 and was negative for CD34 and HLA-DR. Cytogenetics showed a complex karyotype of 45,XY, -14, t(15;17)(q24;21)t(14;21)(q11.2;p13)[10]/ 45, XY, idem, add(5)(q35)[5]/ 45,X,-Y[5]. RT-PCR for PML-RARA was positive for the bcr-3 transcript and FISH was positive for t(15;17) (q24;q21). The take home point from our case is to look for the presence of cells with bundle of Auer rods whenever there is pancytopenia with the presence of myelocyte-like cells with prominent granulations.

Typical, atypical and cryptic t(15;17)(q24;q21) (PML::RARA) observed in acute promyelocytic leukemia: a retrospective review of 831 patients with concurrent chromosome and PML::RARA dual-color dual-fusion FISH studies

The diagnosis of acute promyelocytic leukemia (APL) relies on the identification of PML::RARA fusion. While the majority of APL cases harbor a typical t(15;17)(q24;q21), atypical genetic mechanisms leading to the oncogenic PML::RARA fusion have been reported yet their frequency and scope remain poorly characterized. We assessed the genetic findings of 831 cases with APL investigated with concurrent chromosome banding analysis and dual-color dual-fusion fluorescence in situ hybridization (D-FISH) analysis at our institution over an 18.5-year timeframe. Seven-hundred twenty-three (87%) cases had a typical balanced t(15;17) with both testing modalities. Atypical karyotypic results including complex translocations, unbalanced rearrangements and insertional events occurred in 50 (6%) cases, while 6 (0.7%) cases were cryptic by conventional chromosome studies despite PML::RARA fusion by D-FISH evaluation. Atypical FISH patterns were observed in 48 (6%) cases despite apparently balanced t(15;17) on chromosome banding analysis. Two-hundred fifty (30%) cases displayed additional chromosome abnormalities of which trisomy/tetrasomy 8 (37%), del(7q)/add(7q) (12%) and del(9q) (7%) were most frequent. Complex and very complex karyotypes were observed in 81 (10%) and 34 (4%) cases, respectively. In addition, 4 (0.5%) cases presented as an apparently doubled, near-tetraploid stemline clone. This report provides the largest appraisal of cytogenetic findings in APL with conventional chromosome and PML::RARA D-FISH analysis. By characterizing the frequency and breadth of typical and atypical results through the lens of these cytogenetic testing modalities, this study serves as a pragmatic source of information for those involved in the investigation of APL in both the clinical and research laboratory settings.

[Clinical and genetic characteristics of patients with newly diagnosed acute promyelocytic leukemia: a single-center retrospective of 790 cases]

Objective: To retrospectively analyze the data of Chinese patients with newly diagnosed acute promyelocytic leukemia (APL) to preliminarily discuss the clinical and cytogenetic characteristics. Methods: From February 2004 to June 2020, patients with newly diagnosed APL aged ≥ 15 years who were admitted to the Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Science & Peking Union Medical College were chosen. Clinical and laboratory features were retrospectively analyzed. Results: A total of 790 cases were included, with a male to female ratio of 1.22. The median age of the patients was 41 (15-76) years. Patients aged between 20 and 59 predominated, with 632 patients (80%) of 790 patients classified as low and intermediate risk and 158 patients (20%) of 790 patients classified as high risk. The white blood cell, platelet, and hemoglobin levels at diagnosis were 2.3 (0.1-176.1) ×10(9)/L, 29.5 (2.0-1220.8) ×10(9)/L, and 89 (15-169) g/L, respectively, and 4.8% of patients were complicated with psoriasis. The long-form type of PML-RARα was most commonly seen in APL, accounting for 58%. Both APTT extension (10.3%) and creatinine>14 mg/L (1%) are rarely seen in patients at diagnosis. Cytogenetics was performed in 715 patients with newly diagnosed APL. t (15;17) with additional chromosomal abnormalities were found in 155 patients, accounting for 21.7%; among which, +8 was most frequently seen. A complex karyotype was found in 64 (9.0%) patients. Next-generation sequencing was performed in 178 patients, and 113 mutated genes were discovered; 75 genes had an incidence rate>1%. FLT3 was the most frequently seen, which accounted for 44.9%, and 20.8% of the 178 patients present with FLT3-ITD. Conclusions: Patients aged 20-59 years are the most common group with newly diagnosed APL. No obvious difference was found in the ratio of males to females. In terms of risk stratification, patients divided into low and intermediate risk predominate. t (15;17) with additional chromosomal abnormalities accounted for 21% of 715 patients, in which +8 was most commonly seen. The long-form subtype was most frequently seen in PML-RARα-positive patients, and FLT3 was most commonly seen in the mutation spectrum of APL.

Effect of Additional Cytogenetic Abnormalities on Survival in Arsenic Trioxide-Treated Acute Promyelocytic Leukemia

Complex karyotype is associated with inferior event-free survival in patients who have acute promyelocytic leukemia treated with ATO.

Frontline arsenic trioxide (ATO)–based treatment regimens achieve high rates of long-term relapse-free survival in treating acute promyelocytic leukemia (APL) and form the current standard of care. Refining prognostic estimates for newly diagnosed patients treated with ATO-containing regimens remains important in continuing to improve outcomes and identify patients who achieve suboptimal outcomes. We performed a pooled analysis of exclusively ATO-treated patients at a single academic institution and from the ALLG APML4 and Alliance C9710 studies to determine the prognostic importance of additional cytogenetic abnormalities and/or complex karyotype. We demonstrated inferior event-free survival for patients harboring complex karyotype (hazard ratio [HR], 3.74; 95% confidence interval [CI], 1.63-8.56; P = .002), but not for patients harboring additional cytogenetic abnormalities (HR, 2.13; 95% CI, 0.78-5.82; P = .142). These data support a role for full karyotypic analysis of all patients with APL and indicate a need for novel treatment strategies to overcome the adverse effect of APL harboring complex karyotype.

Cytogenetics of Pediatric Acute Myeloid Leukemia: A Review of the Current Knowledge

Pediatric acute myeloid leukemia is a rare and heterogeneous disease in relation to morphology, immunophenotyping, germline and somatic cytogenetic and genetic abnormalities. Over recent decades, outcomes have greatly improved, although survival rates remain around 70% and the relapse rate is high, at around 30%. Cytogenetics is an important factor for diagnosis and indication of prognosis. The main cytogenetic abnormalities are referenced in the current WHO classification of acute myeloid leukemia, where there is an indication for risk-adapted therapy. The aim of this article is to provide an updated review of cytogenetics in pediatric AML, describing well-known WHO entities, as well as new subgroups and germline mutations with therapeutic implications. We describe the main chromosomal abnormalities, their frequency according to age and AML subtypes, and their prognostic relevance within current therapeutic protocols. We focus on de novo AML and on cytogenetic diagnosis, including the practical difficulties encountered, based on the most recent hematological and cytogenetic recommendations.

Chromosomal Instability in Acute Myeloid Leukemia

Chromosomal instability (CIN), the increasing rate in which cells acquire new chromosomal alterations, is one of the hallmarks of cancer. Many studies highlighted CIN as an important mechanism in the origin, progression, and relapse of acute myeloid leukemia (AML). The ambivalent feature of CIN as a cancer-promoting or cancer-suppressing mechanism might explain the prognostic variability. The latter, however, is described in very few studies. This review highlights the important CIN mechanisms in AML, showing that CIN signatures can occur largely in all the three major AML types (de novo AML, secondary-AML, and therapy-related-AML). CIN features in AML could also be age-related and reflect the heterogeneity of the disease. Although most of these abnormalities show an adverse prognostic value, they also offer a strong new perspective on personalized therapy approaches, which goes beyond assessing CIN in vitro in patient tumor samples to predict prognosis. Current and emerging AML therapies are exploring CIN to improve AML treatment, which includes blocking CIN or increasing CIN beyond the limit threshold to induce cell death. We argue that the characterization of CIN features, not included yet in the routine diagnostic of AML patients, might provide a better stratification of patients and be extended to a more personalized therapeutic approach.

Acute Promyelocytic Leukemia: A Constellation of Molecular Events around a Single PML-RARA Fusion Gene

Although acute promyelocytic leukemia (APL) is one of the most characterized forms of acute myeloid leukemia (AML), the molecular mechanisms involved in the development and progression of this disease are still a matter of study. APL is defined by the PML-RARA rearrangement as a consequence of the translocation t(15;17)(q24;q21). However, this abnormality alone is not able to trigger the whole leukemic phenotype and secondary cooperating events might contribute to APL pathogenesis. Additional somatic mutations are known to occur recurrently in several genes, such as FLT3, WT1, NRAS and KRAS, whereas mutations in other common AML genes are rarely detected, resulting in a different molecular profile compared to other AML subtypes. How this mutational spectrum, including point mutations in the PML-RARA fusion gene, could contribute to the 10%–15% of relapsed or resistant APL patients is still unknown. Moreover, due to the uncertain impact of additional mutations on prognosis, the identification of the APL-specific genetic lesion is still the only method recommended in the routine evaluation/screening at diagnosis and for minimal residual disease (MRD) assessment. However, the gene expression profile of genes, such as ID1, BAALC, ERG, and KMT2E, once combined with the molecular events, might improve future prognostic models, allowing us to predict clinical outcomes and to categorize APL patients in different risk subsets, as recently reported. In this review, we will focus on the molecular characterization of APL patients at diagnosis, relapse and resistance, in both children and adults. We will also describe different standardized molecular approaches to study MRD, including those recently developed. Finally, we will discuss how novel molecular findings can improve the management of this disease.