Project description:Some subtypes of acute myeloid leukemia (AML) share morphologic, immunophenotypic, and clinical features of acute promyelocytic leukemia (APL), but lack a PML-RARA (promyelocytic leukemia-retinoic acid receptor alpha) fusion gene. Instead, they have the retinoic acid receptor beta (RARB) or retinoic acid receptor gamma (RARG) rearranged. Almost all of these AML subtypes exhibit resistance to all-trans retinoic acid (ATRA); undoubtedly, the prognosis is poor. Here, we present an AML patient resembling APL with a novel cleavage and polyadenylation specific factor 6 (CPSF6)-RARG fusion, showing resistance to ATRA and poor response to chemotherapy with homoharringtonine and cytarabine. Simultaneously, the patient also had extramedullary infiltration.
Project description:RationaleSome acute myeloid leukemia (AML) patients present with features mimicking the classical hypergranular subtype of acute promyelocytic leukemia (APL) but without the typical promyelocytic leukemia/retinoic acid receptor α (PML/RARα) rearrangement. Herein, we report an AML patient resembling APL but with nucleoporin 98/retinoid acid receptor gamma gene (NUP98/RARG) fusion transcript and Runt-related transcription factor 1 (RUNX1) mutation.Patient concernsAn 18-year-old male presented at the hospital with a diagnosis of AML.DiagnosesThe patient was diagnosed with bone marrow examination. Bone marrow smear displayed 90.5% promyelocytes. Fluorescence in situ hybridization analysis failed to detect the PML/RARα fusion transcript or RARα amplification. While real-time polymerase chain reaction showed positivity for the NUP98/RARG fusion transcript. G-banding karyotype analysis showed a normal karyotype.InterventionsThe patient showed resistance to arsenic trioxide and standard 3 + 7 chemotherapy, but eventually achieved complete remission through the Homoharringtonine, Cytarabine, and Aclarubicin chemotherapy.OutcomesThese measures resulted in a rapid response and disease control.LessonsAcute myeloid leukemia with the NUP98/RARG fusion gene and the RUNX1 mutation may be a special subtype of AML and may benefit from the alkaloid-based regimen.
Project description:Acute promyelocytic leukemia (APL) is a specific subtype of acute myeloid leukemia (AML) characterized by block of differentiation at the promyelocytic stage and the presence of PML-RARA fusion. In rare instances, RARA is fused with other partners in variant APL. More infrequently, non-RARA genes are rearranged in AML patients resembling APL. However, the underlying disease pathogenesis in these atypical cases is largely unknown. Here, we report the identification and characterization of a NUP98- JADE2 fusion in a pediatric AML patient showing APL-like morphology and immunophenotype. Mechanistically, we showed that NUP98-JADE2 could impair all-trans retinoic acid (ATRA)-mediated transcriptional control and myeloid differentiation. Intriguingly, NUP98-JADE2 was found to alter the subcellular distribution of wild-type JADE2, whose down-regulation similarly led to attenuated ATRA-induced responses and myeloid activation, suggesting that NUP98-JADE2 may mediate JADE2 inhibition. To our knowledge, this is the first report of a NUP98-non-RAR rearrangement identified in an AML patient mimicking APL. Our findings suggest JADE2 as a novel myeloid player involved in retinoic acid-induced differentiation. Despite lacking a rearranged RARA, our findings implicate that altered retinoic acid signaling by JADE2 disruption may underlie the APL-like features in our case, corroborating the importance of this signaling in APL pathogenesis.
Project description:The RARG gene is a member of the nuclear hormone receptor superfamily and shares high homology with RARA and RARB. RARA is involved in translocation with PML in acute promyelocytic leukaemia (APL). Little is known about RARB or RARG rearrangement. RARG fusions were reported in only five APL patients and the partner genes were NUP98, PML and CPSF6. Here, we report NPM1 as a new partner gene of RARG and identify a unique NPM1-RARG-NPM1 chimeric fusion for the first time in an old male with morphological and immunophenotypical features of hypergranular APL but lacking response to all-trans retinoic acid (ATRA) and arsenic trioxide (As2O3) therapy. The structural features of the fusion transcript may account for the clinical resistance of the patient. RARG fusion is rare but recurrent in APL, further investigation in larger cohorts is expected to assess frequency, clinical characteristics and outcomes of RARG-translocation in APL.
Project description:We report a 69-year-old female who was a human T-cell leukemia virus type 1 carrier and exhibited a unique clinical course of developing three hematological malignancies within a short period: diffuse large B-cell lymphoma (DLBCL), chronic myelomonocytic leukemia (CMMoL), and acute myeloid leukemia (AML). Although the blast cells in AML showed typical morphological and immunophenotypical features of acute promyelocytic leukemia (APL), it did not harbor RARα gene fusion and thus initially diagnosed as APL-like leukemia (APLL). The patient developed heart failure with a fulminant clinical course and died soon after the diagnosis of APLL. Retrospective analysis with whole-genome sequencing detected a chromosomal rearrangement between KMT2A and ACTN4 gene loci both in CMMoL and APLL samples, but not in the DLBCL sample. Therefore, CMMoL and APLL were considered to be derived from the same clone with KMT2A translocation associated with prior immunochemotherapy. However, KMT2A rearrangement is rarely found in CMMoL in general and ACTN4 is also a rare partner of KMT2A translocation. Thus, this case did not follow typical transformational process of CMMoL or KMT2A-rearranged leukemia. Importantly, additional genetic alterations, including NRAS G12 mutation, were found in APLL, but not in CMMoL samples, suggesting that they might contribute to leukemic transformation. This report highlights the diverse effects of KMT2A translocation and NRAS mutation on the transformation of hematological cells as well as the importance of upfront sequencing analysis to detect genetic backgrounds for a better understanding of therapy-related leukemia.
Project description:Previous small series have suggested that acute myeloid leukemia with t(8;16) is a distinct morphologic and clinical entity associated with poor prognosis. We describe 18 patients with t(8;16) AML, including their clinical, cytomorphologic, immunophenotypic and cytogenetic features. Half of the patients had extramedullary disease, most commonly leukemia cutis, which often preceded bone marrow involvement and six had therapy-related AML. Patients with t(8;16) AML commonly present with clinical and pathological features that mimic APL, with promyelocytes and promyeloblast-like cells and coagulopathy in most patients. Several patients also presented with marrow histiocytes with hemophagocytosis and erythrophagocytosis. Comprehensive molecular analysis for co-occurring genetic alterations revealed a somatic mutation in RUNX1 in 1 of 6 t(8;16) patients with no known AML mutation in the remaining five t(8;16) patients. This suggests that the t(8;16) translocation could be sufficient to induce hematopoietic cell transformation to AML without acquiring other genetic alteration. These data further support classifying t(8;16) AML as a clinically and molecularly defined subtype of AML marked by characteristic clinical and cytomorphologic features that mimic APL, and is associated with very poor survival.
Project description:We present an acute promyelocytic leukemia (APL) patient with two subtypes of IRF2BP2-RARA, in which the IRF2BP2 gene showed completely new breakpoints. Bone marrow examination revealed morphologic features indicative of APL. However, promyelocytic leukemia-RARA fusion was not detected. A paired-end mRNA sequencing followed by RT-PCR and direct sequencing revealed two types of fusion transcripts between exon 1B of IRF2BP2 and exon 3 of RARA. The patient received all-trans retinoic acid and conventional chemotherapy, but showed resistance. This is the second report of IRF2BP2 involvement in APL, and we describe various breakpoints for the IRF2BP2-RARA fusion gene.
Project description:The PML/RARα fusion protein acts in concert with cooperative genetic events in the development of acute promyelocytic leukemia (APL). However, oncogenic long non-coding RNAs (lncRNAs) cooperating with PML/RARα remain under-explored. Here, we first identified a set of pathogenesis-related lncRNAs, aberrantly expressed in APL using RNA-seq data from a large cohort of acute myeloid leukemia (AML) patients and normal counterparts. Among the pathogenesis-related lncRNAs, one of the evolutionarily conservative lncRNAs CRNDE (Colorectal Neoplasia Differentially Expressed) drew our attention. We found that CRNDE was highly expressed in the disease state but not in the preleukemic stage of APL, suggesting that CRNDE might be a secondary event coordinating with PML/RARα to promote APL development. Functional analysis showed that CRNDE knockdown induced differentiation and inhibited proliferation of APL cells, and prolonged survival of APL mice. Further mechanistic studies showed that CRNDE elicited its oncogenic effects through binding the miR-181 family and thereby regulating NOTCH2. Finally, we found that high CRNDE expression was also significantly correlated with NPM1 mutations and contributed to the differentiation block in NPM1-mutant AML. Collectively, our findings shed light on the importance of oncogenic lncRNAs in the development of AML and provide a promising target for AML therapy.
Project description:BackgroundAcute promyelocytic leukemia (APL) is one of the most life-threatening hematological emergencies and requires a prompt correct diagnosis by cytomorphology and flow cytometry (FCM) with later confirmation by cytogenetics/molecular genetics. However, nucleophosmin 1 muted acute myeloid leukemia (NPM1+ AML) can mimic APL, especially the hypogranular variant of APL. Our study aimed to develop a novel, Radar plot-based FCM strategy to distinguish APLs and NPM1+ AMLs quickly and accurately.MethodDiagnostic samples from 52 APL and 32 NPM1+ AMLs patients were analyzed by a 3-tube panel of 10-color FCM. Radar plots combining all markers were constructed for each tube. Percentages of positive leukemic cells and mean fluorescence intensity were calculated for all the markers.ResultsAPL showed significantly higher expression of CD64, CD2, and CD13, whereas more leukemic cells were positive for CD11b, CD11c, CD15, CD36, and HLA-DR in NPM1+ AMLs. Radar plots featured CD2 expression, a lack of a monocytic component, lack of expression of HLA-DR and CD15, and a lack of a prominent CD11c+ population as recurring characteristics of APL. The presence of blasts with low SSC, presence of at least some monocytes, some expression of HLA-DR and/or CD15, and a prominent CD11c population were recurrent characteristics of NPM1+ AMLs. Radar plot analysis could confidently separate all hypergranular APL cases from any NPM1+ AML and in 90% of cases between variant APL and blastic NPM1+ AML.ConclusionRadar plots can potentially add to differential diagnostics as they exhibit characteristic patterns distinguishing APL and different types of NPM1+ AMLs.