Acute Promyelocytic Leukemia Cases Research Articles

Optical Genome Mapping Reveals Complex and Cryptic Rearrangement Involving PML::RARA Fusion in Acute Promyelocytic Leukemia

Background/objectives: Acute promyelocytic leukemia (APL) is an aggressive subtype of acute myeloid leukemia (AML), characterized by the hallmark translocation t(15;17) resulting in a PML::RARA fusion. Once diagnosed, APL is now considered to be one of the most treatable forms of AML. However, without early detection and treatment, the disease is associated with rapid deterioration and lethal side effects. Methods: We describe a case of diagnostic APL presenting with a normal karyotype, normal RARA break-apart FISH, and unclear, atypical PML/RARA FISH findings. We used optical genome mapping (OGM) to characterize this atypical PML/RARA fusion. Results: OGM allowed for detection of a PML::RARA fusion resulting from a cryptic and complex insertion of PML::RARA into RARA on 17q21.2 whereby a segment of 15q24.1 was inserted into the 17q21.2. The recipient breakpoint of the insertion was at intron 2 of the RARA gene and the donor breakpoint of the insertion was at exon 5/intron 6 of the PML gene. Conclusions: This is the first report of an insertional PML::RARA fusion into the RARA gene on 17q detected by OGM. OGM has demonstrated its utility in a clinical cytogenetics environment, allowing for clearer characterization and diagnosis of various neoplasms.

Beyond the Surface: Uncovering the PML::RARA Fusion in Cytogenetically Cryptic and FISH-Negative Acute Promyelocytic Leukemia- A Case Report and Review of the Literature

Abstract Introduction/Objective Chromosomal t(15;17)(q22;q21), resulting in a fusion between the PML gene on chromosome 15q22 and the RARA gene on chromosome 17q21, is the cytogenetic hallmark of acute promyelocytic leukemia (APL). Conventional karyotyping, along with fluorescence in situ hybridization (FISH), can detect the PML/RARA rearrangements in up to 98% of APL cases. Reverse transcriptase-polymerase chain reaction (RT-PCR) is often used to confirm the initial diagnosis. APL with PML::RARA fusion, which is negative with FISH and conventional karyotyping approaches but positive with RT-PCR, is extremely rare. Herein, we report a de novo APL case that was positive by RT-PCR but negative by cytogenetics and FISH studies. A comprehensive review of the literature was also performed. Methods/Case Report A 23-year-old male presented to the ED for left upper extremity weakness 2 days after post- dental cleaning. Upon admission, he developed intracranial hemorrhage, necessitating urgent decompressive hemicraniectomy. Blood smear revealed promyelocytes; flow cytometric analysis showed a CD13+, CD33+, MPO+, CD117+, CD34-, and HLA-DR- abnormal cell population. STAT interphase FISH analyses for PML/RARA fusion and RARA break-apart were negative. A diagnosis of APL was made based on abnormal promyelocytes and characteristic flow cytometry findings. ATRA was immediately administrated. However, the post-operative course was complicated by significant coagulopathy, pancytopenia, and multi-organ failure, and the patient expired 7 days later. RT-PCR returned positive for PML::RARA long fusion transcript; the conventional cytogenetics study was uninformative. The clinical, pathological, and genetic features of 31 cases of FISH/Cytogenetics-negative APL harboring cryptic rearrangements of PML-RARA, detected by RT-PCR in the literature, have been reviewed. Various detection methods were also discussed. Results (if a Case Study enter NA) N/A Conclusion Conventional cytogenetics, FISH and RT-PCR analysis are complementary studies for all clinical suspected APL cases. The clinicopathological characteristics also play critical roles in APL diagnosis when genetic confirmation of the PML::RARA fusion is unavailable.

A Rare Case of Acute Promyelocytic Leukemia with Concomitant PML-RARA Fusion and TP53 Loss/ider(17)(q10)t(15;17) Showing Complete Clinical and Molecular response: A Case Report

Abstract Introduction/Objective To report a case with rare cytogenetic abnormality: a patient with newly diagnosed acute promyelocytic leukemia (APL) with cytogenetic findings of t(15;17)(q24;q21), trisomy 8 and ider(17)(q10)t(15;17)-TP53 loss. The presence of isochromosome 17q may indicate the possibility of an unfavorable outcome. However, the case showed complete clinical and molecular response. Methods/Case Report A case of a 53-year-old female with history of ITP post-splenectomy presented with persistent hematuria, easy bruising, and worsening fatigue. She had mild microcytic anemia, moderate thrombocytopenia, 3% promyelocytes, and 14% blasts on differential CBC count. With increased PT, PTT, LDH, Uric acid and decreased fibrinogen level, APL was clinically suspected. The patient was initiated on all-trans retinoic acid (ATRA), allopurinol, and IV fluids. Bone marrow (BM) biopsy confirmed the diagnosis with unusual cytogenetic findings. The patient underwent induction and consolidation therapies (4 weeks each) with ATRA plus Arsenic Trioxide (ATO) and followed- up with a series of marrow biopsies, cytogenetic and molecular studies. Results (if a Case Study enter NA) The patient demonstrated complete clinical, histological, and molecular response. She tolerated the treatment without major side effects, showing improvement in CBC counts, coagulation profile and tumor lysis labs. Initial BM exam revealed hypercellularity with infiltrating sheets of atypical hypergranular promyelocytes (~80%) and minimal residual left trilineage hematopoiesis. Flow cytometry revealed a CD34 negative, CD117 variable abnormal promyelocyte population (~67% of total events). FISH was positive for PML/RARA translocation (15; 17) and TP53 loss. Karyotype showed 46,XX,der(15)t(15;17)(q24;q21),ider(17)(q10)t(15;17)[12]/47,idem,+8[9]. By the end of treatment, BM biopsy was normocellular with trilineage hematopoiesis and no definitive evidence of acute leukemia or increase in blasts. The Karyotype was normal. Quantitative PCR for PML-RARA was negative, indicating complete molecular remission. Conclusion In this unique case of APL with unusual cytogenetic abnormalities the literature demonstrates controversial data. The patient achieved complete clinical and molecular remission following standard treatment. This may indicate the limited prognostic significance of these additional cytogenetic abnormalities in this case.

Characteristics and Prognosis of "Acute Promyelocytic Leukemia-like" Nucleophosmin-1-Mutated Acute Myeloid Leukemia in a Retrospective Patient Cohort.

Background: AML with NPM1 mutation is the largest subcategory of AML, representing about 35% of AML cases. It is characterized by CD34 negativity, which suggests a relatively differentiated state of the bulk of leukemic blasts. Notably, a significant subset of NPM1-mutated AML cases also exhibit HLA-DR negativity, classifying them as "double-negative", and mimicking, therefore, the CD34- HLA-DR- immunophenotype of acute promyelocytic leukemia (APL). Objectives: This study focuses on the "acute promyelocytic leukemia-like" ("APL-like") subset of NPM1-mutated AML, which can be challenging to distinguish from APL at presentation, prior to confirming RARa translocations. We aim to investigate the hematologic and immunophenotypic parameters that may aid to its distinction from APL. Additionally, we explore differences in genetic profile and prognosis between "APL-like" and "non-APL-like" NPM1-mutated AML cases. Methods: We conducted a retrospective evaluation of 77 NPM1-mutated AML cases and 28 APL cases. Results: Morphological characteristics, hematologic parameters (such as DD/WBC and PT/WBC), and specific immunophenotypic markers (including SSC, CD64, and CD4) can assist in the early distinction of "APL-like" NPM1-mutated AML from APL. Regarding differences in genetic profiles and outcomes between "APL-like" and non-"APL-like" NPM1-mutated AML cases, we observed a significantly higher incidence of IDH1/2 /TET2 mutations, along with a significantly lower incidence of DNMT3A mutations in the "APL-like" subset compared to the non-"APL-like" subset. The frequency of Ras-pathway and FLT3 mutations did not differ between these last two groups, nor did their prognoses. Conclusions: Our findings contribute to a comprehensive characterization of NPM1-mutated AML, enhancing diagnostic accuracy and aiding in the detailed classification of the disease. This information may potentially guide targeted therapies or differentiation-based treatment strategies.

Outcomes of Acute Promyelocytic Leukaemia in Paediatric Patients: Insights from a Low-Middle-Income Country.

To describe the prognostic variables and course of paediatric acute promyelocytic leukaemia (APL) in Pakistan. Cohort study. Place and Duration of the Study: Department of Paediatric Oncology, Combined Military Hospital, Rawalpindi, Pakistan, from January 2012 to December 2022. Patients aged 1-15 years, clinically confirmed APL with promyelocytic leukaemia- retinoic acid receptor alpha (PML-RARA) were enrolled. Initial admission included a thorough examination, recording demographic and clinical data, reporting time, prior treatment, and socioeconomic status. Statistical analysis used SPSS 25.0, with significance at p <0.05. This study included 50 cases of APL. Out of which, 32 (64%) were males and 18 (34%) were females. The mean age at diagnosis was 7.02 ± 3.86 years. Pallor (96%) and fever (88%) were common presentations. The average white blood cell count was 28.70 ± 35.39 x109/L. Treatment protocols include 48% International Consortium for Childhood (ICC)-APL, and 52% arsenic trioxide (ATO). High-risk cases were 54%. Neutropenic fever and differentiation syndrome were common induction complications. Delays over one month increased induction deaths (6.7 to 35%, p = 0.011), reducing disease-free survival (DFS), (76.7 to 35%, p = 0.001), and overall survival (OS), (80 to 45%, p = 0.007). After 40.90 ± 45.19 months' follow-up, 10-year OS and DFS were 66.0% and 60.0%, respectively. The best OS and DFS, at 80%, were observed in standard-risk cases treated with ATO. Neutropenic fever and bleeding were the primary causes of mortality in paediatric APL induction. Treatment delay was a key prognostic factor. ATO-based therapy offered safer, improved DFS, and OS suitable for primary healthcare settings. Acute promyelocytic leukaemia, Chemotherapy, Neutropenic fever.

Treatment of a STAT5b::RARα positive case of APL in a patient not eligible for intensive chemotherapy.

Acute promyelocytic leukaemia (APL) with a STAT5b::RARα gene fusion is an extremely rare subtype of APL characterised by resistance to conventional therapies and extremely poor prognosis. This case highlights that whilst APL with variant RARα translocations are rare, they do pose significant challenges both diagnostically and in their clinical management. This case, in the first instance, demonstrates the importance of using a combination of molecular techniques including next generation sequencing (NGS) for diagnosis particularly in morphological and immunophenotypic typical APL which appears negative by confirmatory testing. Secondly, our patient represents, to the best of our knowledge, the first documented example of this rare disease that has been managed with, and shown sensitivity to low-dose cytarabine (LDAC) in combination with venetoclax (Ven). This case demonstrates that although treatment options are extremely limited for patients not eligible for intensive chemotherapy non-intensive options do show increasing promise.

Survivorship Struggles: Navigating Etiologies and Clinical Parameters of Febrile Neutropenia During Induction Chemotherapy in Acute Leukemia Patients.

Background Acute leukemia, characterized by the uncontrolled proliferation of immature white blood cell precursors, poses significant challenges during induction chemotherapy, including the elevated risk of febrile neutropenia and its associated complications. Our study aims to explain the clinical and etiological parameters of these patients in a resource-limited setting. Methods This retrospective study focused on a total of 102 adult patients with acute leukemia who developed febrile neutropenia during the induction chemotherapy phase. Patients with disease relapse, prior bone marrow transplantation, and cases of acute promyelocytic leukemia were excluded from the study. Demographical characteristics, symptoms at presentation, diagnoses, infectious causes, and outcomes were systematically reported. Infectious etiologies and detailed culture reports were meticulously tabulated, and subsequent data were analyzed. Results Of the 102 patients, 43 (42.2%) were males, with a mean age of 31.9 ± 6.5 years. During the induction chemotherapy, a total of 31 patients died of complicated febrile neutropenia. Severe vomiting was the most common symptom present in 37 (36.2%), followed by cough in 35 (34.3%) and loose stools in 28 (27.5%). Community-acquired pneumonia, neutropenic sepsis, and neutropenic colitis were among the most common etiologies of febrile neutropenia. A total of 72 (70.6%) patients had culture-proven multidrug-resistant Gram-negative bacteremia that contributed to poor outcomes. Conclusions Acute leukemia patients undergoing induction chemotherapy face high infection-associated mortality due to their immunocompromised state. Inadequate infection control measures and antimicrobial resistancecontribute to the emergence of multidrug-resistant organisms. Enhanced infection prevention strategies and evidence-based antibiotic prescription guidelines are need of time in resource-limited settings such as Pakistan to address febrile neutropenia complications and bridge the existing care gap in its management.

Clinical analysis of 82 cases of acute promyelocytic leukemia with PML-RARα short isoform in children and adults.

Acute promyelocytic leukemia (APL) with PML/RARα fusion gene is a distinct variant of acute myeloid leukemia. According to the different break sites of the PML gene, there are three transcripts: Long (bcr1), Variant (bcr2) and Short (bcr3). We retrospectively analyzed 82 APL cases with PML-RARα short isoform. A total of 384 patients with APL were seen, of which 85(22.14%) had PML/RARα short isoform (bcr3) and 82 met the inclusion criteria. The median age was 33.5 years (range, 2-72 years). The incidences of hemorrhage in the intermediate- and high-risk group were higher, but only the incidence between medium and low risk differed statistically (P=0.006), and the incidences of fever, fatigue, splenomegaly, and lymph node enlargement and differentiation syndrome (DS) in those groups were not statistically significant (P>0.05). FLT3 gene mutation rate and the mortality rate of the high-risk group were significantly higher than that of other groups (P=0.040 and P=0.004, P=0.041 and P=0.037, respectively). The mortality rate was lowest (4.26%) in the group treated with ATRA combined with arsenic and anthracycline. The 3-year OS and the 3-year DFS of the low and intermediate-risk group were better (P=0.019 and P=0.017, respectively). ATRA combined with arsenic and anthracycline had significant impact on outcomes in APL with PML-RARα short isoform.

Acute Promyelocytic Leukemia Complicated by Deep Venous Thrombosis, Pulmonary Thromboembolism, and Hematemesis

Acute promyelocytic leukemia (APML) is a myeloid leukemia classified as M3-AML. It is known for its bleeding diathesis, which is predominantly driven by disseminated intravascular coagulation and primary hyperfibrinolysis. However, thrombotic events are relatively less common. A combination of bleeding and thrombotic events is rare and poses a challenge in management. We present a case of acute promyelocytic leukemia complicated by deep venous thrombosis, pulmonary thromboembolism, and hematemesis.

A Rare Case of Acute Promyelocytic Leukemia with Morphologic Dysplasia and Unique Molecular Characteristics

A Rare Case of Acute Promyelocytic Leukemia with Morphologic Dysplasia and Unique Molecular Characteristics

Spinal epidural abscess mimicking chloroma

Background: Spinal epidural abscess (SEA) is a rare and generally challenging condition. It represents a challenge in terms of diagnosis and treatment due to the low incidence, vague presentation, and rapid neurologic deterioration. Case Presentation: A 40-year-old gentleman who was previously healthy was presented with a 2-week history of decreased vision associated with fever and cough one week before the eye symptoms. The patient was admitted as a case of acute promyelocytic leukemia. And was started on chemotherapy, which was complicated by septicemia and was shifted to the intensive care unit. Three weeks after admission he started to have severe non-radicular neck pain. He also had bilateral lower limb pain spasm-like in nature. Patient denies any history of trauma, weakness, numbness, saddle anesthesia or loss of sphincter control. Labs showed leukopenia, anemia and thrombocytopenia. Bone marrow result showed hypercellularity with active trilineage hematopoiesis and no immunomorphological evidence of abnormal promyelocytes or maturation arrest. He underwent C3-C4 laminectomy and evacuation of epidural pus collection. Intra-operative course was free of complication. Upon post-operative assessment he was hemodynamically stable, his neck pain was better with morphine doses and he was able to mobilize it. Conclusion: Spinal epidural abscess can mimic chloroma clinically and radiologically, however, diffusion with the images and enhancement is essential for proper assessment since a proper medical and surgical intervention is needed.

Identification of concurrent STAT3::RARA and RARA::STAT5b fusions in a variant APL case.

Acute promyelocytic leukemia (APL) with typically PML::RARA fusion gene caused by t (15;17) (q22; q12) was distinguished from other types of acute myeloid leukemia. In a subset of patients with APL, t (15;17) (q22;q21) and PML::RARA fusion cannot be detected. In this report, we identified the coexistence of STAT3::RARA and RARA::STAT5b fusions for the first time in a variant APL patient lacking t (15;17)(q22;q21)/PML::RARA fusion. Then, this patient was resistant to all-trans retinoic acidcombined arsenic trioxide chemotherapy. Accurate detection of RARA gene partners is crucial for variant APL, and effective therapeutic regime is urgently needed.

Harnessing intermolecular G-quadruplex-based spatial confinement effect for accelerated activation of CRISPR/Cas12a empowers ultra-sensitive detection of PML/RARA fusion genes

Accurate detection and classification of the three isoforms of PML/RARA genomic fragments are crucial for predicting disease progression, stratifying risk, and administering precise drug therapies in acute promyelocytic leukemia (APL). In this study, we have developed a highly specific nucleic acid detection platform capable of quantifying the long isoform of the three main PML-RARA isoforms at a constant temperature. This platform integrates the strengths of the CRISPR/Cas12a nuclease-based method and the rolling circle amplification (RCA) technique. Notably, the RCA-assisted CRISPR/Cas12a trans-cleavage system incorporates a spatial confinement effect by utilizing intermolecular G-quadruplex structures. This innovative design effectively enhances the local concentration of CRISPR/Cas12a, thereby accelerating its cleaving efficiency towards reporter nucleic acids and enabling the detection of PML/RARA fusion gene expression through spectroscopy. The robust detection of PML/RARA fusion gene from human serum samples validates the reliability and potential of this platform in the screening, diagnosis, and prognosis of APL cases. Our findings present an approach that holds significant potential for the further development of the robust CRISPR/Cas sensor system, offering a rapid and adaptable paradigm for APL diagnosis.

Trinary Fusion with Ligand Binding Domain Castration Is Crucial in Rarg-Driven APL and Render Unresponsive to ATRA Via Allosteric Disability Mechanism

Introduction All-trans retinoic acid (ATRA) has been used with great success in acute promyelocytic leukemia (APL) cases with PML::RARA fusion gene (FG). There are still PML::RARA negative cases that manifest as APL, and they often carry FGs involved in RARA, RARB, or RARG. X::RARG positive APL ( RARG-APL) cases have been increasingly reported in recent years, thanks to the utilization of transcriptome sequencing (RNA-seq) and whole genome sequencing (WGS). Almost all evaluable RARG-APL cases were resistant to ATRA, and no mechanism has been elucidated. Intriguingly, cells transformed by artificial X::RARG were extremely sensitive to ATRA (PMID: 25510432), indicating intricate mechanisms unrevealed. This study first and systematically unveils the distinctive features and pivotal molecular mechanism of RARG-driven APL. Methods A total of 22 RARG-APL cases with RNA-seq and WGS data from 11 centers were enrolled (Fig. 1A). We used Arriba for routine FG calling and manually investigated the non-coding fusion sequence. Reverse transcription PCR (RT-PCR) and Sanger sequencing were used to validate the FGs and to determine whether the RARG 5′ and 3′ fusion events were located on the same cistron. The responsiveness of the fusion proteins to ATRA was evaluated using an optimized UAS/GAL4 reporter system. Results Among the cases enrolled, there were 15 males and 7 females, aged 0.9-69 (median 38) years. Morphological and immunophenotype analyses all showed features of APL. Routine FGs calling reported RARG fusion to a 5′ partner in each case, with variable RARG splicing sites (Fig. 1A). There were 7 RARG 5' partner genes, with CPSF6, HNRNPC, and NUP98 observed in multiple cases. In the 3 index cases, we identified that they all had RARG 3‘ fusion events besides the 5‘ one (Fig. 1A). RT-PCR confirmed that the 5′ and 3′ RARG fusion events were in the same cistron in each case. Such as, the fusion transcript is the insertion of RARG-e4_9 (e refers to exon) between NPM1-e4 and e11 in case #G1, rather than two separate transcripts of NPM1-e4:: RARG-e4 and RARG-9:: NPM1-e11. We named this novel form of tandem splicingtrinary fusion. Analysis of the 19 validation cases further confirmed that all RARG-APL cases had RARG 3′ fusion events (Fig. 1A). We also validated that the 5′ and 3′ RARG fusion events were in the same cistron in 3 more cases, of which archived cDNA were available. Remarkably, the 3' splicing sits of all cases were consistently at the end of RARG-e9, leading to RARG-e10 truncation. The RARG 3' partner gene was the same as its 5' partner in 11 cases. But in the other 11 cases, the RARG 3' partner was a transposon element (TE) sequence, the most common being a LINE-L2a (8 cases). Sequences analysis indicated that the committed locus of the involved LINE-L2a was at 4.2 Kbp upstream of the RARG gene. Gene expression analysis confirmed the aberrant activation of the involved TEs. All TEs involved in the RARG 3' fusions confer a poly_A signal sequence to the fusion transcript, which was essential for a mRNA. In-depth analysis indicated that TEs participate in the formation of RARG-FGs through a transposition mechanism rather than a translocation mechanism. RARG-e10 encodes helix 11_12 (H11_12) of its ligand binding domain (LBD), which plays a pivotal role in allosteric response to ATRA (PMID: 31178221). The trinary fusion protein with RARG LBD-H11_12 castration will lose responsiveness to ATRA via an allosteric disability mechanism (Fig. 1B, 1C). Experiments confirmed that cells transfected with X::RARG fusion with intact LBD responded well to ATRA, while fusion with LBD-H11_12 castration showed no response to physiological and pharmacological concentrations of ATRA (Fig. 1D, 1E). Conclusions This study clearly revealed that trinary fusion and LBD castration are crucial molecular etiologies in RARG-APL. The trinary fusion orchestrates the aberrant activation of RARG (5‘ splicing) and the complete allosteric disability in responding to ATRA (3‘ splicing). Thus, this study elegantly explains the mechanism of leukemogenesis and the extensive ATRA resistance of RARG-APL. The formation of trinary fusion requires two steps of genome splicing or transposition events, which explains the rarity of RARG-APL. This also clarifies that RARG-APL has a significant disparity in molecular mechanism from PML::RARA-positive APL, and we suggest that it should be considered as a separate entity of acute myeloid leukemia.

Impact of Arsenic Trioxide in the Treatment of Higher Risk Acute Promyelocytic Leukemia

INTRODUCTION: Acute promyelocytic leukemia (APL) accounts for 5-8% of all cases of acute myeloid leukemia (AML). The combination of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) without chemotherapy is currently the reference treatment of standard APL (ie with baseline white blood count (WBC)&amp;lt;10 G/L), curing about 90% of the patients. However, the prognosis of high-risk APL (ie with WBC&amp;gt;10 G/L) remains more challenging, with higher rates of early death and relapse. Here we compared the French practices for the treatment of high-risk APL patients whether patients were treated with ATRA-Chemo or ATRA-ATO according to physician decision, and evaluate the response rates, overall survival (OS) and leukemia-free survival (LFS) in the real-life settings. PATIENTS AND METHODS: ATO (in combination with ATRA) became accessible in France for the first line treatment of standard risk APL in 2012, but some patients with high-risk APL also received the same combination (generally with some form of cytoreductive chemotherapy) from that date. We retrospectively analyzed cases of high-risk APL diagnosed between 2010 and 2021 in 12 French centers, constituting a cohort of 135 patients with diagnostic of APL confirmed by cytogenetic, FISH and molecular biology assays. RESULTS: Among the 135 patients with WBC&amp;gt;10 G/L, 88 (65%) were classified as APL variant according to FAB classification. Median age was 46 years (range 18-89) and 62 % were male. Median diagnostic WBC was 39.1 G/L (range 10-270) and median platelet count was 27 G/L (range 5-344). At diagnosis, 112 patients (83%) had hemorrhagic manifestations and disseminated intravascular coagulation (DIC) was observed in 124 patients (92%). Pulmonary and cerebral leucostasis were reported in 10 (7%) and 14 (10%) patients, respectively. Eighty-five patients received corticosteroid prophylaxis (81 (95%) with Dexamethasone and 5 (5%) with Prednisolone). Induction therapy consisted in ATRA-ATO for 50 patients (38%) while 85 patients (62%) were treated with ATRA combined with chemotherapy (anthracycline and cytarabin) but without ATO. All patients treated with ATO were cytoreduced: 7 with Hydroxyurea (14%), 17 with Idarubicin (34%) and 26 with both (52%). 29 patients treated without ATO during induction were cytoreduced with Hydroxurea (34%). Most patients experienced one or more adverse events during induction, including sepsis (49 in the ATO group versus 71 in the non ATO group, 98% versus 83.5%, p=0.01), differentiation syndrome (20 in the ATO group versus 27 in the non ATO group, 40% versus 31.7%, p=0.33), transaminase increased (14 in ATO group versus 11 in the non ATO group, 28% versus 12.9%, p=0.03), and bleeding (7 in the ATO group versus 13 in the non ATO group, 14% versus 15.3%, p=0.8). Following induction, 110 patients (81%) achieved complete remission (CR): 45 in the ATO group and 65 in the non ATO group (90% versus 76.4%, p=0.052). One patient (receiving ATRA with chemotherapy) was refractory, and 24 patients experienced early death (5 in the ATO group and 19 in the non ATO group, 10% versus 22.3%, p=0.069) mostly due to hemorrhage or sepsis. Median time between diagnosis and early death was 4.5 days (0-42). Relapse was observed in 6 (5.5 %) patients (5 patients treated without ATO and 1 patient with ATO during induction). After a median follow-up of 34.6 months (0-121.1), OS at 3 years was significantly higher for the ATO group (89.9% (81.8-98.7) versus 75.1% (66.3-84.9) for the non ATO group, p= 0.035, Figure). LFS at 3 years was significantly higher for the ATO group (87.6% (78.7-97.4) versus 71.2% (62-81.7) for the non ATO group, p=0.028). CONCLUSIONS: The survival outcomes were significantly poorer in high-risk APL patients treated without ATO during induction, regardless of the cytoreduction strategy. The toxicity profile of ATO was acceptable. Combining ATO and ATRA limits the use of cytotoxic chemotherapy, which could reduce myelosuppression and long-term complications such as cardiotoxicity and secondary myeloid neoplasms. Early disease-related mortality, due to haemorrhagic or infectious complications, remains the major issue for these patients but tend to be reduced in those receiving ATRA-ATO based regiment. This retrospective study shows that ATO-ATRA and limited chemotherapy could be a better approach than ATRA and standard intensive chemotherapy in terms of early deaths, LFS and OS.

Partner Gene Associated Trinary Fusion and Orchestration of Multiple Molecular Events in Acute Promyelocytic Leukemia with Variant Rara Fusion Genes

Background All-trans retinoic acid (ATRA) has been used with great success in acute promyelocytic leukemia (APL) cases with PML::RARA fusion gene (FG). There are still PML::RARA negative cases manifest as APL. So far, 19 RARA fusion partner genes have been reported, with all reported as 5′ partners ( X::RARA). Intriguingly, a significant proportion of X::RARA cases were resistant to ATRA, and mechanisms are yet to be elucidated. Here we report the finding of a novel type of trinary fusion and the orchestrating of multiple molecular events that confer leukemogenesis and ATRA resistance in X::RARA-APL. Methods A total of 23 cases (Fig. 1A) with RNA-seq and WGS data from 10 centers were enrolled. We used Arriba for routine FG calling and manually investigated the nonconventional fusion sequence. RT-PCR, Sanger sequencing, and optical genome mapping (OGM) were used to validate the FGs and to determine whether the RARA 5′ and 3′ fusion events were located on the same cistron. The responsiveness of the fusion proteins to ATRA was evaluated using an optimized UAS/GAL4 reporter system. Results Among the cases enrolled, there were 17 males and 6 females, aged 3-66 (median 32) years. Morphological and immunophenotype analyses all showed features of APL. We first identified the STAT3::RARA fusion event in an ATRA-resistant case (the index case, #A1). Moreover, we noticed another fusion event of truncated RARA exon 9 and a 3′ partner sequence that did not map to any annotated protein-coding genes. Further analysis determined it was the RC sequence of the transposable element (TE) LTR40a with the annotated loci at 17p11.2. Both OGM (at the genome level) and RT-PCR (Fig. 1A) confirmed that the two RARA fusion events were in the same cistron. Thus, the fusion transcript being STAT3::RARA::LTR40a-RC spliced in tandem, but not separate transcripts of STAT3::RARA and RARA::LTR40a-RC. We named this novel form of tandem splicingtrinary fusion. We, therefore, recruit X::RARA-APL cases to investigate the recurrence of RARA 3′ fusion. We identified 9 RARA 5′ partner genes in 23 cases (Fig. 1B), with TTMV -ORF2, STAT5B, STAT3, IRF2BP1, THRAP3, and TNRC18 in multiple cases. Ten (43.5%) cases also harbor RARA 3′ fusion partners. The partner of case #A1_8 were TEs, and the partner of case #A9_10 was the same gene as their 5′ one. Thirteen cases did not harbor 3′ fusions. Notably, both TNRC18::RARA cases (#15_16) carry mutations on their RARA ligand binding domain (LBD) at the primary onset. Gene expression analysis confirmed the aberrant activation of the involved TEs. All TEs involved in the RARA 3' fusions confer a poly_A signal sequence, which was essential for a mRNA. In-depth analysis indicated that TEs participate in forming RARA-FGs through a transposition mechanism rather than a translocation mechanism. The molecular events addition to RARA 5′ splicing showed a 5′ partner associated pattern: all of the 4 STAT3::RARA and 4 STAT5B::RARA cases harbor TEs as their 3′ partner, both TNRC18::RARA cases carry LBD mutation, while all 7 TTMV -ORF2::RARA cases did not harbor 3′ splicing or LBD mutation. Remarkably, although the RARA 3' splicing sites varied, they all resulted in partial or complete exon 9 truncation. RARA exon 9 encodes helix 11_12 (H11_12) of its LBD, which is pivotal in allosteric response to ATRA. The RARA trinary fusion will result in LBD-H12 or H11_12 castration due to the 3' splicing, then lead to losing responsiveness to ATRA via an allosteric disability mechanism (Fig. 1C, 1D). Experiments confirmed that cells transfected with STAT3::RARA fusion with intact LBD responded well to ATRA, while both the fusion in case #A1 and artificial fusion with LBD-H12 castration showed no response to physiological and pharmacological concentrations of ATRA (Fig. 1E). Conclusions This is the first report of pathological trinary fusion, the TEs and transposition mechanism participating in composing pathological fusion genes, and the RARA LBD castration confers ATRA resistance in X::RARA-APL. Also, there might be another synergistic mechanism of RARA 5' fusion and LBD mutation. The formation of trinary fusion and gain of LBD mutation, in addition to X::RARA fusion, requires more genome splicing or transposition or mutation events, which explains the rarity of X::RARA-APL. This study highlights mechanisms of partner gene-associated trinary fusion and the orchestrating of multiple molecular events in the leukemogenesis in X::RARA-APL cases.

Automated Cytogenetic Classifier (ACC) to Support Accurate Clinical Decision Making in Acute Myeloid Leukaemia

Introduction Cytogenetic analysis is a recommended test in newly diagnosed AML but requires accurate interpretation of the International System for Human Cytogenomic Nomenclature (ISCN). Keeping up to date across recent published classifications - WHO, the European Leukaemia Net (ELN) and International Consensus Classification (ICC) - is critical for accurate prognostic assessment, but can be challenging for clinicians and laboratory scientists. Furthermore, eligibility to access state-funded treatments in the UK is dictated by certain cytogenetic results. We previously developed a webapp that integrates cytogenetic, molecular and clinical features to aid accurate classification, prognostication and provide treatment recommendations in AML (Coats et al, BJH 2021). To further improve the webapp we have developed a cytogenetic classifier to automatically interpret reports written in ISCN format. In this study we aimed to validate the automated cytogenetic classifier (ACC) in identifying abnormalities that feature in the new WHO, ELN and ICC classifications. Methodology Software for the ACC was written in Python to: 1. count the number and type of karyotypic abnormalities (subdivided into number of monosomies, complete chromosome gains and structural changes) 2. identify presence of clinically relevant, named, abnormalities that feature in international classifications (categorised as an individual abnormalityg. t(9;11)(p21.3;q23.3), or a generic abnormality e.g. any translocation involving 11q23.3). Cytogenetic reports of 50 consecutive AML cases with abnormal karyotypes analysed by Bristol Haematological Oncology Diagnostic Service (BHODS) were selected (training cohort). Each report was uploaded to the ACC and its output independently checked for accuracy. Following review of the software's performance, adjustments to the ACC were made. The updated ACC (Figure 1) analysed 98 additional reports from two other laboratories, UCLH and OUH (validation cohort). Results The ACC analysed 49/50 cytogenetic reports from the BHODS laboratory. One report could not be read by the ACC. The correct quantity of abnormalities was identified in 49/49 cases analysed. Where relevant named abnormalities occurred, these were detected in 79/80 instances. One case of acute promyelocytic leukaemia containing an idic(17p) was not identified as containing an abnormal 17p. Additionally, in one report with a complex karyotype, a monosomy 13 was erroneously detected by the ACC. Adjustments were made to the ACC such that it could analyse all 50 cases with 100% accuracy. The updated ACC then analysed 98 cases from the validation cohort. The correct quantity of abnormalities was detected in 97/ 98 cases. In one case with a highly complex karyotype containing a tetraploid clone, the ACC incorrectly counted 48, as opposed to 45, abnormalities. Clinically relevant, named, abnormalities were correctly identified in 178/179 instances. In one case, containing a 4-way translocation, the ACC did not identify the t(9;11) abnormality. Discussion Here, we show that the updated ACC is accurate in identifying the number and type of karyotypic abnormalities relevant to AML from different laboratories. Reduced accuracy in counting the number of abnormalities in highly complex karyotypes (i.e. &amp;gt;40 abnormalities) is not likely to impact clinical interpretation. Further validation work is needed to analyse 3 and 4-way translocations. User warnings have been added to the ACC for karyotypes containing multiple-translocations and tetraploid/triploid clones to improve clinical safety. The ACC can support clinical decision-making by streamlining cytogenetic interpretation from across multiple clinical classifications. It can be used as a stand-alone programme or integrated into more sophisticated decision support tools. The ACC has the potential to be updated to interpret cytogenetic reports from other classifications or haematological malignancies. The ACC is available as a webapp (Streamlit (ts482-cytogenetics-calculator-extractorstreamlit-w7dq9p.streamlit.app). Figure 1. Flowchart of the methodology of the updated automated cytogenetic classifier (ACC).

Exudative Retinal Detachment as a Prodromal Manifestation of Differentiation Syndrome in Acute Promyelocytic Leukemia: A Case Report and Review of Literature

The ocular manifestations of the differentiation syndrome (DS) are rarely reported in the literature with only six cases published until now. Patients with acute promyelocytic leukemia (APL) who undergo treatment with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) are especially susceptible to developing DS. This is a serious diagnosis with a life-threatening impact on some patients, however, amenable to prophylaxis and treatment by systemic corticosteroids. An exudative retinal detachment (ERD) may either complicate or herald the development of DS. In this article, we present a case of APL who developed ERD in advance of DS symptoms, its multimodal imaging characteristics, and review the published articles concerning this rare disease manifestation.

Prevalence of Gene Rearrangement by Multiplex PCR in De Novo Acute Myeloid Leukemia in Adult Iraqi Patients.

Gene rearrangements of acute myeloid leukemia (AML) play a significant role in categorizing patients and provide valuable information about prognosis and treatment choices. However, in Iraq, the prevalence and prognostic significance of gene rearrangements in AML have not been previously examined. This study utilized a multiplex reverse transcription real-time PCR (RT-qPCR) system to identify gene rearrangements in a group of 115 adult patients from Iraq who had been diagnosed with De Novo AML. The diagnosis of AML was confirmed through blood film and flow cytometry. The ethical committee of the College of Medicine at the University of Baghdad provided approval for this research study. In this study, 66.1% of the patients diagnosed with acute myeloid leukemia (AML) exhibited distinct genetic abnormalities. Among these abnormalities, the most frequent was the rearrangement involving the KMT2A gene, observed in 19.9% of the patients. The risk stratification analysis revealed that 40% of the patients were classified as having a favorable risk, 4.3% as intermediate risk, and 25.2% as adverse risk. A subtype of AML known as core-binding factor (CBF) AML was identified in 21.7% of the cases, with 84% of these patients achieving complete remission. The NPM-RARA gene rearrangement, found in 43% of acute promyelocytic leukemia (APL) cases, was associated with a 71% complete remission rate. Among patients with KMT2A rearrangement, which accounted for 19.9% of all AML cases, the MLL-AF10 rearrangement was the most common, although only one patient with KMT2A rearrangement achieved complete remission. Furthermore, the analysis of demographic data revealed a significant association between increased risk and advanced age, presence of comorbidities, and FAB classification (M0 subtype). The prevalence of genetic rearrangements in Iraqi De Novo AML patients is higher than the global trend, highlighting the importance of genetic characterization in risk assessment and treatment decisions.

Clinical and genomic characterization of an ATRA-insensitive acute promyelocytic leukemia variant with a FNDC3B::RARB fusion.

The promyelocytic leukemia-retinoic acid receptor-α (PML::RARA) fusion is the hallmark of acute promyelocytic leukemia (APL) and is observed in over 95% of APL cases. RARA and homologous receptors RARB and RARG are occasionally fused to other gene partners, which differentially affect sensitivity to targeted therapies. Most APLs without RARA fusions have rearrangements involving RARG or RARB, both of which frequently show resistance to all-trans-retinoic acid (ATRA) and/or multiagent chemotherapy for acute myeloid leukemia (AML). We present a 13-year-old male diagnosed with variant APL with a novel FNDC3B::RARB in-frame fusion that showed no response to ATRA but responded well to conventional AML therapy. While FNDC3B has been identified as a rare RARA translocation partner in ATRA-sensitive variant APL, it has never been reported as a fusion partner with RARB and it is only the second known fusion partner with RARB in variant APL. We also show that this novel fusion confers an RNA expression signature that is similar to APL, despite clinical resistance to ATRA monotherapy.