ider(17)(q10)t(15;17) associated with relapse and poor prognosis in a pediatric patient with acute promyelocytic leukemia

Rapid Detection of PML::RARA Fusions in Acute Promyelocytic Leukemia: CRISPR/Cas9 Nanopore Sequencing with Adaptive Sampling

Acute promyelocytic leukemia (APL) accounts for approximately 10-15% of newly diagnosed acute myeloid leukemia cases and presents with coagulopathy and bleeding. Prompt diagnosis and treatment are required to minimize early mortality in APL as initiation of all-trans retinoic acid therapy rapidly reverses coagulopathy. The PML::RARA fusion is a hallmark of APL and its rapid identification is essential for rapid initiation of specific treatment to prevent early deaths from coagulopathy and bleeding and optimize patient outcomes. Given limitations and long turnaround time of current gene fusion diagnostic strategies, we have developed a novel amplification-free nanopore sequencing-based approach with low cost, easy setup, and fast turnaround time. We termed the approach CRISPR/Cas9-enriched nanopore sequencing with adaptive sampling (CENAS). Using CENAS, we successfully sequenced breakpoints of typical and atypical PML::RARA fusions in APL patients. Compared with the standard-of-care genetic diagnostic tests, CENAS achieved good concordance in detecting PML::RARA fusions in this study. CENAS allowed for the identification of sequence information of fusion breakpoints involved in typical and atypical PML::RARA fusions and identified additional genes (ANKFN1 and JOSD1) and genomic regions (13q14.13) involving the atypical fusions. To the best of our knowledge, involvements of the ANKFN1 gene, the JOSD1 gene, and the 13q14.13 genomic region flanking with the SIAH3 and ZC3H13 genes have not been reported in the atypical PML::RARA fusions. CENAS has great potential to develop as a point-of-care test enabling immediate, low-cost bedside diagnosis of APL patients with a PML::RARA fusion. Given the early death rate in APL patients still reaches 15%, and ~10% of APL patients are resistant to initial therapy or prone to relapse, further sequencing studies of typical and atypical PML::RARA fusion might shed light on the pathophysiology of the disease and its responsiveness to treatment. Understanding the involvement of additional genes and positional effects related to the PML and RARA genes could shed light on their role in APL and may aid in the development of novel targeted therapies.

Pediatric acute myeloid leukemia patients with i(17)(q10) mimicking acute promyelocytic leukemia: Two case reports

BACKGROUND

Chromosome i(17)(q10) abnormality is mainly associated with chronic myeloid leukemia (CML), myelodysplastic syndrome/myeloproliferative tumors (MDS/MPD), and acute myeloid leukemia (AML). The role of i(17)(q10) in AML is still unknown, the differences between AML and acute promyelocytic leukemia (APL)-like AML with i(17)(q10) need more research. This study aimed to investigate the clinical characteristics and laboratory evidence of 2 AML cases with i(17)(q10), similar to APL phenotype.

CASE SUMMARY

Both pediatric patients were males; case 1 had newly diagnosed AML, and case 2 showed relapsed tumor after 1 year of drug withdrawal. Bone marrow cell morphology, chromosome karyotype analysis, Fully-instrumented submersible housing test, immunological assays, molecular biological methods, and blood tumor panoramic gene test were performed. All-trans retinoic acid (ATRA) combined with arsenic acid (As2O3) were used in the first course of treatment. Bone marrow was dominated by abnormal promyelocytic granulocytes. Karyotype test revealed i(17)(q10) isochromosome. Immunological phenotype mainly included positive expressions of CD9, CD13, CD33, and CD38. Case 1 suffered intracranial hemorrhage after re-chemotherapy and died on D162. For case 2, on D145 and D265, bone marrow promyelocytic granulocytes accounted for 2%. Flow cytometric residual lesion detection showed no abnormal immunophenotype cells. The copy number of WT1 gene in two cases were 1087 and 1010, respectively, and the expression rates were 55.29% and 59.5%, respectively.

CONCLUSION

ATRA, As2O3, and chemotherapy may be ineffective in treating APL-like AML with i(17)(q10) but without t(15;17) and PML-RARA fusion gene.

Prognostic significance of isochromosome 17q in hematologic malignancies

Isochromosome 17q [i(17q)] with its two identical long arms is formed by duplication of the q arm and loss of the short p arm. The breakpoint in chromosome 17 that allows the formation of this isochromosome is located at 17p11.2, and the ~240 kb region with its large, palindromic, low-copy repeat sequences are present here. The region is highly unstable and susceptible to a variety of genomic alterations which may be induced by or without toxic agents. One molecular consequence of i(17q) development is the obligatory loss of a single TP53 allele of the tumor suppressor P53 protein located at 17p13.1. Isochromosome 17q is involved in cancer development and progression. It occurs in combination with other chromosomal defects (complex cytogenetics), and rarely as a single mutation. The i(17q) rearrangement has been described as the most common chromosomal aberration in primitive neuroectodermal tumors and medulloblastomas. This isochromosome is also detected in different hematological disorders. In this article, we analyze literature data on the presence of i(17q) in proliferative disorders of the hematopoietic system in the context of its role as a prognostic factor of disease progression. The case reports are added to support the presented data. Currently, there are no indications for the use of specific treatment regimens in the subjects with a presence of the isochromosome 17q. Thus, it is of importance to continue studies on the prognostic role of this abnormality and even single cases should be reported as they may be used for further statistical analyses or meta-analyses.

A rare case of acute promyelocytic leukemia with ider(17)(q10)t(15;17)(q22;q21) and favorable outcome

Background

Chromosomal rearrangements in addition to t(15;17) have been reported in 25-40% of APL patients, with a large predominance of trisomy 8. Other abnormalities are far less frequent, particularly as ider(17), and the prognostic significance is still unclear.

Case presentation

We present the case of a patient with t(15;17)(q22;q21), der(15)t(15;17) and ider(17)(q10)t(15;17)(q22;q21). In particular, the RT-PCR result for PML-RARA of this patient was a false negative and mutational analysis of AML-related genes showed SNP rs2454206 in the TET2 gene and yielded negative findings in other genes including AML1, ASXL1, CEBPA, DNMT3A, FLT3, KIT, NPM1, TP53, and U2AF1. After the early usage of arsenic trioxide combinated with ATRA and vigorous supportive treatment to maintain PLT ≥30×10⁹/L and FIB >1500 mg/L, this patient was under MMR and HCR without any clinical symptoms or signs until now.

Conclusion

False negative reslults of RT-PCR analysis for PML-RARA are rare in APL and ider(17) is even more infrequent. To our knowledge, this is the first reported case of APL with ider(17) and false negative RT-PCR analysis results. The role of ider(17) in APL is still an ongoing investigation and limited by the small number of published cases. The patient reported here benefited from vigorous supportive treatment during the combination of ATRA and arsenic trioxide in induction chemotherapy and the clinical outcome was favorable.

[Application of immunophenotypic analysis and molecular genetics in the diagnosis of acute promyelocytic leukemia]

Objective: To investigate the application values of immunophenotypic analysis and molecular genetics in the diagnosis of acute promyelocytic leukemia (APL) . Methods: The retrospective analyses of flow cytometric (FCM) immunophenotypic anyalysis, chromosome karyotype and chromosome fluorescence in situ hybridization (FISH) of 798 outpatient or hospitalization APL patients referred to our hospital between May 2012 and December 2017 were performed to further study the application values of FCM and molecular genetics in the diagnosis of APL. Results: The sensitivity and specificity of FCM were 91.9% and 98.7% respectively. The typical characteristic immunophenotype for APL was as of follows: a high SSC, absence of expression of cluster differntiation (CD) CD34 and HLA-DR, and expression or stronger expression of CD33, consistent expression of CD13, CD9, CD123, expression of CD56, CD7, CD2 (sometimes) . The rest 10% of the cases harbored atypical APL phenotypes, generally accompanied by CD34 and/or HLA-DR expression, decreased SSC and often accompanied by CD2 expression, it was difficult to definitively diagnose APL by this FCM phenotype, and their diagnoses depended on the results of genetics or molecular biology tests. Compared with normal individuals, complex karyotypes APL with t (15;17) translocation, other variant translocations and variant t (11;17) , t (5;17) had no significant differences in terms of their FCM phenotypes. Conclusions: FCM could rapidly and effectively diagnose APL. Despite the fact that complex karyotypes with various additional chromosomal abnormalities were detected in approximately one third of APL cases in addition to the pathognomonic t (15;17) (q22;q21) , they had no observable impact on the overall immunophenotype. Molecular and genetic criteria were the golden criteria for the diagnosis of APL. About 10% of immunophenotyping cases relied on molecular genetics for diagnosis.

Early mortality in acute promyelocytic leukemia: Potential predictors

Acute promyelocytic leukemia (APL) is a rare leukemia characterized by the balanced reciprocal translocation between the promyelocytic leukemia gene on chromosome 15 and the retinoic acid receptor α (RARα) gene on chromosome 17, and accounts for 10-15% of newly diagnosed acute myeloid leukemia each year. The combined use of all-trans retinoic acid and arsenic trioxide (ATO) as primary therapy has markedly improved the survival rate of patients with APL. Mortality in the first 30 days following therapy remains a major contribution to treatment failure. In the present study, published data was reviewed with a focus on the factors associated with early mortality. When treated with ATO as a primary treatment, the fms-like tyrosine kinase-internal tandem deletion has no impact on early mortality. Low lymphoid enhancer binding factor-1 expression may be a reliable marker for early mortality and the target of therapy if it could be proven by further studies. Cluster of differentiation (CD)56+ and CD34+/CD2+ may be candidates to select high-risk patients. The risk of early mortality in APL still cannot be predicted via the cell surface makers, despite multiple studies on their prognostic significance. Typically, a complex translocation did not alter the survival rate in patients with APL; however, if an abnormal karyotype [e.g., Ide(17), ZBTB16/RARα and STAT5B/RARα] appeared singularly or as part of a complex mutation, there is a high possibility of early mortality if clinicians are unable to identify or monitor it.

A Pediatric Acute Promyelocytic Leukemia With a Rare Karyotype of ider(17)(q10)t(15;17) and Favorable Outcome: A Case Report

Acute promyelocytic leukemia (APL) is a specific malignant hematological disorder with a diagnostic hallmark of chromosome translocation t(15;17)(q22;q21). As a very rare secondary cytogenetic aberration in pediatric APL, ider(17q) (q10)t(15;17) was suggested to be a poor prognostic factor based on previous case reports.Here, we report a pediatric APL case with a rare karyotype of ider(17)(q10)t(15;17). Bone marrow aspiration, immunophenotyping, molecular biology, cytogenetic, and fluorescence in situ hybridization (FISH) analyses were performed at initial diagnosis and during the treatment.A 6-year-old boy was brought to our hospital with the chief complaint of bleeding gums twice and intermittent fever for 3 days in January 2013. He was diagnosed as low-risk APL according to the 2012 NCCN guideline on APL, with the expression of PML-RARA (bcr3 subtype) and the karyotype of 46,XY, der(15)t(15;17)(q22;q21),ider(17)(q10)t(15;17), which was further verified by FISH. The patient was treated through combination all-trans retinoic acid (ATRA) and arsenic with daunorubicin according to the 2012 NCCN guideline for APL. Continuous hematological completed remission (HCR) and major molecular remission (MMR) were achieved with normal karyotype for >28 months after induction chemotherapy.Different from previously reported cases, this pediatric APL patient with ider(17)(q10)t(15;17) displays favorable clinical outcomes, which might be related to the low-risk classification and arsenic treatment during the treatment. It suggests that ider(17)(q10)t(15;17) may not be the sole determinant for worse outcomes in pediatric APL and implies that more contributed factors should be considered for pediatric APL prognosis.

An ider(17)(q10)t(15;17) with spliced long-type PML-RARA fusion transcripts in a case of acute promyelocytic leukemia

The ider(17)(q10)t(15;17) is a relatively rare chromosomal rearrangement in acute promyelocytic leukemia patients. We describe herein a case of APL with a poor prognosis and ider(17)(q10)t(15;17)(q22;q12), which was confirmed by fluorescence in situ hybridization. Reverse transcription polymerase chain reaction (RT-PCR) and sequencing of PCR products were used to detect the PML-RARA fusion gene and delineate the sequence of the fusion transcripts. We found that the PML-RARA fusion gene of this patient was the long isoform, which only generated transcripts of a splice variant lacking PML exon 5 and a splice variant lacking PML exons 5 and 6. Although the clinical and prognostic significance of patients with an ider(17)(q10)t(15;17) remains unclear, a combination of cytogenetics and molecular biology analysis should be performed to obtain further information about this chromosomal abnormality.

A rare case with typical acute promyelocytic leukemia morphology associated with isolated isochromosome 17q without RARα rearrangement

Isolated isochromosome 17q has rarely been reported in hematologic tumor patients. A 37-year-old man was admitted with fever and weakness. Blood routine test showed anemia and thrombocytopenia. The morphology and immunology of bone marrow cells conform to classic acute promyelocytic leukemia (APL). But the karyotype showed isolated isochromosome 17q without t(15;17) (q22;q12). Rverse transcriptase polymerase chain reaction (RT-PCR) for PML -RARa was negative and fluorescence in situ hybridization (FISH) analysis showed no RARa gene rearrangements.The patient responded poorly to all trans retinoic acid and traditional chemotherapy with daunorubicin and cytarabine and survived only 43 days after diagnosis. The pathogenesis and the best treatment choice for this kind of patients are not clear currently.

A rare case of microgranular acute promyelocytic leukemia associated with ider(17)(q10)t(15;17) in an old-age patient

We present a rare case of microgranular variant acute promyelocytic leukemia (APL) associated with ider(17)(q10)t(15;17)(q22;q12) of an old-age patient. The initial chromosome study showed a 46,XX,del(6)(?q21q25),der(15)t(15;17)(q22;q12),ider(17)(q10)t(15;17)[10]/47,sl,+ider(17)(q10)t(15;17)[3]/46,XX[16]. FISH signals from a dual color dual fusion translocation PML-RARA probe were consistent with the results of conventional cytogenetics. Because of the rarity of ider(17)(q10)t(15;17) in microgranular APL, further studies on both gene dosage effect of this chromosomal abnormality and the influence of ider(17)(q10)t(15;17) on clinical features such as prognosis, survival, and treatment response of APL cases are recommended.