Ph-positive chronic myeloid leukemia with t(8;21)(q22;q22) in blastic crisis

Transformation into acute myeloid leukemia with t(8;21)(q22;q22.1); RUNX1::RUNX1T1 from JAK2-mutated essential thrombocythemia: a case report

BACKGROUND

Blast transformation is a rare but well-recognized event in Philadelphia-negative myeloproliferative neoplasms associated with a poor prognosis. Secondary acute myeloid leukemias evolving from myeloproliferative neoplasms are characterized by a unique set of cytogenetic and molecular features distinct from de novo disease. t(8;21) (q22;q22.1); RUNX1::RUNX1T1, one of the most frequent cytogenetic abnormalities in de novo acute myeloid leukemia, is rarely observed in post-myeloproliferative neoplasm acute myeloid leukemia. Here we report a case of secondary acute myeloid leukemia with t(8;21) evolving from JAK2-mutated essential thrombocythemia.

CASE PRESENTATION

The patient was a 74-year-old Japanese woman who was referred because of thrombocytosis (platelets 1046 × 109/L). Bone marrow was hypercellular with increase of megakaryocytes. Chromosomal analysis presented normal karyotype and genetic test revealed JAK2 V617F mutation. She was diagnosed with essential thrombocythemia. Thrombocytosis had been well controlled by oral administration of hydroxyurea; 2 years after the initial diagnosis with ET, she presented with leukocytosis (white blood cells 14.0 × 109/L with 82% of blasts), anemia (hemoglobin 91 g/L), and thrombocytopenia (platelets 24 × 109/L). Bone marrow was hypercellular and filled with 80% of myeloperoxidase-positive blasts bearing Auer rods. Chromosomal analysis revealed t(8;21) (q22;q22.1) and flow cytometry presented positivity of CD 13, 19, 34, and 56. Molecular analysis showed the coexistence of RUNX1::RUNX1T1 chimeric transcript and heterozygous JAK2 V617F mutation in leukemic blasts. She was diagnosed with secondary acute myeloid leukemia with t(8;21)(q22;q22.1); RUNX1::RUNX1T1 evolving from essential thrombocythemia. She was treated with combination chemotherapy with venetoclax and azacytidine. After the first cycle of the therapy, blasts disappeared from peripheral blood and decreased to 1.4% in bone marrow. After the chemotherapy, RUNX1::RUNX1T1 chimeric transcript disappeared, whereas mutation of JAK2 V617F was still present in peripheral leukocytes.

CONCLUSIONS

To our best knowledge, the present case is the first one with JAK2 mutation preceding the acquisition of t(8;21). Our result suggests that t(8;21); RUNX1::RUNX1T1 can be generated as a late event in the progression of JAK2-mutated myeloproliferative neoplasms. The case presented typical morphological and immunophenotypic features associated with t(8;21) acute myeloid leukemia.

Clinical Outcomes of Patients With Chronic Myeloid Leukemia With Concurrent Core Binding Factor Rearrangement and Philadelphia Chromosome

BACKGROUND

Acquisition of additional cytogenetic abnormalities (ACAs) in addition to Philadelphia chromosome is frequently observed in patients with chronic myeloid leukemia (CML) in advanced phase. The presence of core binding factor (CBF) translocations determines the diagnosis of acute myeloid leukemia regardless of blast percentage, and CBF rearrangements are rarely identified as ACAs.

PATIENTS AND METHODS

A retrospective chart review of patients with CML who had CBF rearrangement, t(8;21) or inv(16), in Philadelphia chromosome-positive clones was conducted. Additional cases of CML with CBF rearrangements were identified through literature review.

RESULTS

Between August 1997 and December 2014, we identified 11 patients who had Philadelphia chromosome and CBF rearrangement in the same clones: 1 (9%) with t(8;21) and 10 (91%) with inv(16). Nine (82%) patients were in blast phase, and 2 (18%) in second chronic phase. Four (36%) patients received tyrosine kinase inhibitor monotherapy, 2 (18%) received tyrosine kinase inhibitor and chemotherapy, and 5 (45%) received chemotherapy only. Three (27%) patients achieved complete remission with incomplete count recovery, and 4 (36%) had no response after the initial therapy. Three (27%) patients underwent allogeneic stem cell transplantation. The median event-free survival and overall survival for the 11 patients were 2 months and 6 months, respectively. Literature review identified 14 patients with CML with CBF rearrangement with a median overall survival of 14 months.

CONCLUSION

Acquisition of CBF rearrangement in addition to Philadelphia chromosome is a rare phenomenon associated with poor prognosis. CBF rearrangements as ACAs in patients with CML can be considered high-risk features.

Coexistence of recurrent chromosomal abnormalities and the Philadelphia chromosome in acute and chronic myeloid leukemias: report of five cases and review of literature

Progression of chronic myelogenous leukemia (CML) is frequently accompanied by cytogenetic evolution. Additional genetic abnormalities are seen in 10–20% of CML cases at the time of diagnosis, and in 60–80% of cases of advanced disease. Unbalanced chromosomal changes such as an extra copy of the Philadelphia chromosome (Ph), trisomy 8, and i(17)(q10) are common. Balanced chromosomal translocations, such as t(3;3), t(8;21), t(15;17), and inv(16) are typically found in acute myeloid leukemia, but rarely occur in CML. Translocations involving 11q23, t(8;21), and inv(16) are relatively common genetic abnormalities in acute leukemia, but are extremely rare in CML. In the literature to date, there are at least 76 Ph+ cases with t(3;21), 47 Ph+ cases with inv(16), 16 Ph+ cases with t(8;21), and 9 Ph+ cases with t(9;11). But most of what has been published is now over 30 years old, without the benefit of modern immunophenotyping to confirm diagnosis, and before the introduction of treatment regimes such as TKI. In this study, we explored the rare concomitant occurrence of coexistence current chromosomal translocation and t(9;22) in CML or acute myeloid leukemia (AML).

Long-term stability of demethylation after transient exposure to 5-aza-2'-deoxycytidine correlates with sustained RNA polymerase II occupancy

DNA methyltransferase inhibitors are currently the standard of care for myelodysplastic syndrome and are in clinical trials for leukemias and solid tumors. However, the molecular basis underlying their activity remains poorly understood. Here, we studied the induction and long-term stability of gene reactivation at three methylated tumor suppressor loci in response to the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-azaCdR) in human breast cancer cells. At the TMS1/ASC locus, treatment with 5-azaCdR resulted in partial DNA demethylation, the reengagement of RNA polymerase II (Pol II), and a shift from a repressive chromatin profile marked with H3K9me2 and H4K20me3 to an active profile enriched in H3ac and H3K4me2. Using a single-molecule approach coupling chromatin immunoprecipitation with bisulfite sequencing, we show that H3ac, H3K4me2, and Pol II selectively associated with the demethylated alleles, whereas H3K9me2 preferentially marked alleles resistant to demethylation. H4K20me3 was unaffected by DNA demethylation and associated with both unmethylated and methylated alleles. After drug removal, TMS1 underwent partial remethylation, yet a subset of alleles remained stably demethylated for over 3 months. These alleles remained selectively associated with H3K4me2, H3ac, and Pol II and correlated with a sustained low level of gene expression. TMS1 alleles reacquired H3K9me2 over time, and those alleles that became remethylated retained H3ac. In contrast, CDH1 and ESR1 were remethylated and completely silenced within approximately 1 week of drug removal, and failed to maintain stably unmethylated alleles. Our data suggest that the ability to maintain Pol II occupancy is a critical factor in the long-term stability of drug-induced CpG island demethylation.

“Acute myelogenous leukemia like” translocations in CML blast crisis: Two new cases of inv(16)/t(16;16) and a review of the literature

We describe two patients with CML blast crisis with clonal evolution affecting 16q22 (t(16;16)(p13;q22) and inv(16)(p13;q22), abnormalities of core binding factor, usually found in de novo acute myeloid leukemia (AML)). The bone marrow of both cases showed myelomonocytic (M4) differentiation and eosinophilia. Both patients had prominent extramedullary disease and had poor response to treatment. A literature search focused on patients with CML and additional chromosome changes more typical of AML, revealed that the morphology of the blasts correlated with the finding typical of the underlying "AML" cytogenetic abnormality and an overall very poor clinical outcome, even in the groups with "favorable" AML type translocations.

Pathogenesis of acute myeloid leukaemia and inv(16)(p13;q22): a paradigm for understanding leukaemogenesis?

Acute myeloid leukaemia (AML) has been proposed to arise from the collaboration between two classes of mutation, a class I, or proliferative, mutation and a class II, or blocking, mutation. A limitation of this so-called 'two-hit' hypothesis has been the lack of identifiable proliferative and blocking mutations in most AML cases. However, it is now known that the CBFbeta-MYH11 fusion gene in AML and inv(16), by disrupting the normal transcription factor activity of core binding factor (CBF), functions as a class II mutation. In addition, nearly 70% of patients with AML and inv(16) are known to possess mutually exclusive mutations of the receptor tyrosine kinases (RTKs), c-KIT and FLT3, as well as RAS genes, that provide a class I, or proliferative, signal. AML and inv(16), therefore, is one of the best understood of the acute leukaemias at the genetic level and so provides a paradigm for the 'two-hit' hypothesis of leukaemogenesis. This paper reviews the recent advances in the molecular pathology of AML and inv(16) and discusses possible therapeutic implications of the current pathogenetic model.

p190BCR-ABL rearrangement as a secondary change in a case of acute myelo-monocytic leukemia with inv(16)(p13q22)

The simultaneous occurrence of two specific primary chromosomal changes in hematological malignancies is rare. We report on a patient with acute myelo-monocytic leukemia and both inv(16)(p13q22) and t(9;22)(q34;q11) with a p190(BCR-ABL) rearrangement. The t(9;22)(q34;q11) translocation appears to be a secondary change. Similar secondary BCR-ABL rearrangements have already been described and, in most cases, the chimeric protein was of the p190(BCR-ABL) type as in our case. A complete remission was obtained by conventional chemotherapy followed with imatinib mesylate maintenance therapy. At relapse, the BCR-ABL transcripts were undetectable, which suggests that imatinib mesylate could be an effective adjuvant treatment in acute leukemia with a secondary t(9;22)(q34;q11).

Cytogenetic and molecular genetic evolution of chronic myeloid leukemia

Chronic myeloid leukemia (CML) is genetically characterized by the presence of the reciprocal translocation t(9;22)(q34;q11), resulting in a BCR/ABL gene fusion on the derivative chromosome 22 called the Philadelphia (Ph) chromosome. In 2-10% of the cases, this chimeric gene is generated by variant rearrangements, involving 9q34, 22q11, and one or several other genomic regions. All chromosomes have been described as participating in these variants, but there is a marked breakpoint clustering to chromosome bands 1p36, 3p21, 5q13, 6p21, 9q22, 11q13, 12p13, 17p13, 17q21, 17q25, 19q13, 21q22, 22q12, and 22q13. Despite their genetically complex nature, available data indicate that variant rearrangements do not confer any specific phenotypic or prognostic impact as compared to CML with a standard Ph chromosome. In most instances, the t(9;22), or a variant thereof, is the sole chromosomal anomaly during the chronic phase (CP) of the disease, whereas additional genetic changes are demonstrable in 60-80% of cases in blast crisis (BC). The secondary chromosomal aberrations are clearly nonrandom, with the most common chromosomal abnormalities being +8 (34% of cases with additional changes), +Ph (30%), i(17q) (20%), +19 (13%), -Y (8% of males), +21 (7%), +17 (5%), and monosomy 7 (5%). We suggest that all these aberrations, occurring in >5% of CML with secondary changes, should be denoted major route abnormalities. Chromosome segments often involved in structural rearrangements include 1q, 3q21, 3q26, 7p, 9p, 11q23, 12p13, 13q11-14, 17p11, 17q10, 21q22, and 22q10. No clear-cut differences as regards type and prevalence of additional aberrations seem to exist between CML with standard t(9;22) and CML with variants, except for slightly lower frequencies of the most common changes in the latter group. The temporal order of the secondary changes varies, but the preferred pathway appears to start with i(17q), followed by +8 and +Ph, and then +19. Molecular genetic abnormalities preceding, or occurring during, BC include overexpression of the BCR/ABL transcript, upregulation of the EVI1 gene, increased telomerase activity, and mutations of the tumor suppressor genes RB1, TP53, and CDKN2A. The cytogenetic evolution patterns vary significantly in relation to treatment given during CP. For example, +8 is more common after busulfan than hydroxyurea therapy, and the secondary changes seen after interferon-alpha treatment or bone marrow transplantation are often unusual, seemingly random, and occasionally transient. Apart from the strong phenotypic impact of addition of acute myeloid leukemia/myelodysplasia-associated translocations and inversions, such as inv(3)(q21q26), t(3;21)(q26;q22), and t(15;17)(q22;q12-21), in CML BC, only a few significant differences between myeloid and lymphoid BC are discerned, with i(17q) and TP53 mutations being more common in myeloid BC and monosomy 7, hypodiploidy, and CDKN2A deletions being more frequent in lymphoid BC. The prognostic significance of the secondary genetic changes is not uniform, although abnormalities involving chromosome 17, e.g., i(17q), have repeatedly been shown to be ominous. However, the clinical impact of additional cytogenetic and molecular genetic aberrations is most likely modified by the treatment modalities used.

Additional translocation (8;21)(q22;q22) in a patient with Philadelphia-positive chronic myelogenous leukaemia in the blastic phase

We report a case of Philadelphia-positive chronic myelogenous leukaemia in blastic phase with the additional translocation (8;21)(q22;q22), which is frequent in acute myeloid leukaemia but not in chronic myelogenous leukaemia. The t(8;21) was not detected in the chronic phase, and was the only additional chromosomal anomaly in the blastic clone. Reverse transcription-polymerase chain reaction revealed the AML1/ETO fusion transcript in the cells of blastic phase but not in those of chronic phase. Regarding t(9;22), the breakpoint on chromosome 22 occurred in the mu-BCR region of the BCR gene, resulting in hybrid BCR/ABL mRNA with an e19a2 junction. Our findings provided molecular evidence that t(8;21) can occur as an additional genetic change in Philadelphia-positive chronic myelogenous leukaemia.

Aml1/ETO and Pml/RARA rearrangements in a case of AML-M2 acute myeloblastic leukemia with t(15;17)

We report a case of acute myeloid leukemia FAB-type 2 with a translocation t(15;17)(q22;q12) On the basis of the cytological findings, a translocation t(8;21)(q22;q22) was suspected. FISH analyses using specific probes for t(15;17) and t(8;21) detected both PML/RARalpha and AML1/ETO rearrangements in a few percentage of cells. This case demonstrates the complexities that may occur between cytology and cytogenetic findings and the usefulness of FISH methods to detect an AML1/ETO rearrangement only suspected by cytological examination of bone marrow smears.

Cytogenetic and fluorescence in situ hybridization analyses of hematologic malignancies in Korea

Cytogenetic analysis was performed in 86 cases of hematologic malignancy, using conventional cytogenetic analysis and fluorescence in situ hybridization (FISH) analysis at two university hospitals in Korea between 1993 and 1995. In addition to well-known anomalies, some unusual abnormalities were found, such as t(17;22), trisomy 9 combined with t(14;17), (2;7) and Philadelphia chromosome in CML; t(1;12), t(11;22), t(9;17), and t(12;21) in AML; trisomy 11 in MDS; t(2;9) and complex t(8;8;13;14) in ALL. The results of FISH analysis in interphase nuclei using a translocation probe for CML and APL showed more than 85% positive cells in CML, and 75% positive cells in APL.

Fusion of the Platelet-Derived Growth Factor Receptor β to a Novel Gene CEV14 in Acute Myelogenous Leukemia After Clonal Evolution

Chromosomal translocations involving band 5q31-35 occur in several hematologic disorders. A clone with a t(5; 14)(q33; q32) translocation appeared at the relapse phase in a patient with acute myelogenous leukemia who exhibited a sole chromosomal translocation, t(7; 11), at initial diagnosis. After the appearance of this clone, the leukemia progressed with marked eosinophilia, and combination chemotherapy was ineffective. Southern blot analysis showed a rearrangement of the platelet-derived growth factor receptor β (PDGFRβ) gene at 5q33 which was not observed at initial diagnosis. This translocation resulted in a chimeric transcript fusing the PDGFRβ gene on 5q33 with a novel gene, CEV14, located at 14q32. Expression of the 5′ region of the PDGFRβ cDNA, upstream of the breakpoint, was not detected. However, the 3′ region of PDGFRβ, which was transcribed as part of the CEV14-PDGFRβ fusion gene, was detected. A partial cDNA for a novel gene, CEV14, includes a leucine zipper motif and putative thyroid hormone receptor interacting domain and is expressed in a wide range of tissues. The expression of a CEV14-PDGFRβ fusion gene in association with aggressive leukemia progression suggests that this protein has oncogenic potential.

Fusion of the Platelet-Derived Growth Factor Receptor β to a Novel Gene CEV14 in Acute Myelogenous Leukemia After Clonal Evolution

Chromosomal translocations involving band 5q31-35 occur in several hematologic disorders. A clone with a t(5; 14)(q33; q32) translocation appeared at the relapse phase in a patient with acute myelogenous leukemia who exhibited a sole chromosomal translocation, t(7; 11), at initial diagnosis. After the appearance of this clone, the leukemia progressed with marked eosinophilia, and combination chemotherapy was ineffective. Southern blot analysis showed a rearrangement of the platelet-derived growth factor receptor β (PDGFRβ) gene at 5q33 which was not observed at initial diagnosis. This translocation resulted in a chimeric transcript fusing the PDGFRβ gene on 5q33 with a novel gene, CEV14, located at 14q32. Expression of the 5′ region of the PDGFRβ cDNA, upstream of the breakpoint, was not detected. However, the 3′ region of PDGFRβ, which was transcribed as part of the CEV14-PDGFRβ fusion gene, was detected. A partial cDNA for a novel gene, CEV14, includes a leucine zipper motif and putative thyroid hormone receptor interacting domain and is expressed in a wide range of tissues. The expression of a CEV14-PDGFRβ fusion gene in association with aggressive leukemia progression suggests that this protein has oncogenic potential.

Persistence of AML1 rearrangement in peripheral blood cells in t(8;21)

Translocation (8;21)(q22;q22) involves fusion of the AML1 gene with the ETO gene, generating an AML1/ETO fusion transcript that can be detected by the polymerase chain reaction (PCR). Persistence of the AML1/ETO transcript has been demonstrated by PCR in patients with t(8;21) in long-term remission, but the rearranged AML1 gene could not be detected by Southern analysis, showing that the t(8;21) clone existed as minimal residual disease (MRD). In one patient with t(8;21), AML1/ETO could be detected serially in the peripheral blood. However, rearrangement of the AML1 gene was also found to persist. Furthermore, the hybridization intensities of the rearrangement bands showed that some of the mature myeloid cells also possessed the AML1 rearrangement. Thus, the presence of AML1/ETO in this case appeared to be due to persistence of the mutated clone as mature myeloid cells instead of MRD, implying that the t(8;21) had occurred in a preleukemic myeloid progenitor cell capable of differentiation.

Use of the polymerase chain reaction in the detection of AML1/ETO fusion transcript in t(8;21)

BACKGROUND

t(8;21)(q22;q22), found in acute myeloid leukemia (AML) and occasionally in myelodysplasia (MDS), results in the fusion of the AML1 gene on 22q22 to the ETO gene on 8q22, generating a chimeric AML1/ETO transcript, which is a molecular marker of the translocation.

METHODS

Reverse transcription-polymerase chain reaction (RT-PCR), with two pairs of nested AML1 and ETO primers, was used to amplify the AML1/ETO fusion transcript. The Kasumi-1 cell line was used as a positive control.

RESULTS

RT-PCR has a sensitivity of 0.0001% (10(-6)), corresponding to detection of 0.5 picograms of leukemic RNA in the presence of 0.5 micrograms of normal RNA. Using this approach, patients with t(8;21) (three patients with de novo AML, one with therapy-related AML, and one patient with myelodysplasia) yielded the same 222 base pair PCR product, suggesting that the breakpoints occurred at the same AML1 and ETO introns as previously reported. Three patients were still PCR-positive when in complete remission after chemotherapy and two experienced relapse. However, in another three patients with t(8;21) who were in remission for 2 months, 2 years, and 3 1/2 years, respectively, PCR was negative.

CONCLUSION

RT-PCR is a sensitive method of detection of t(8;21), and is useful in the monitoring of minimal residual leukemia. As the junction of AML1/ETO appears to be constant, RT-PCR may offer a quick and accurate diagnosis of t(8;21).

De-novo acute myeloid leukemia with trilineage myelodysplasia (AML/TMDS) and myelodysplastic remission marrow (AML/MRM)

Trilineage myelodysplasia (TMDS) in de novo acute myeloid leukemia (AML) at initial diagnosis and during remission has not been well recognized yet. In this review we describe the characteristics of de novo AML with TMDS (AML/TMDS) and with myelodysplastic remission marrow (AML/MRM) in view of the in vivo and in vitro disease progression. AML/TMDS was found in ten (10.4%) of 96 patients with de novo AML at initial diagnosis and AML/MRM were also observed in three (5.0%) out of 60 cases in remission after chemotherapy in our hospital between 1984 and 1992. Abnormal karyotypes were seen in six of nine AML/TMDS patients and all of the three AML/MRM. Karyotypic changes occurred in two of AML/TMDS and two of AML/MRM during their clinical course. Using the long term bone marrow culture (LTBMC) system that allowed abnormal clones to survive preferentially to the clone of normal karyotype, latent clones were detected in three patients with AML/TMDS and three of AML/MRM as in the cases of myelodysplastic syndrome (MDS) and AML transformed from MDS (MDS/AML) but not in the typical AML without myelodysplastic changes. Four of these cases exhibited the same karyotypes as seen during the clinical course. Primary abnormal karyotypes prior to clonal evolution were also observed in two of the AML/MRM. Taken together, both AML/TMDS and AML/MRM are similar to MDS/AML with respect to their myelodysplastic background and potential for disease progression and may have progressed to AML from the preceding disease status more rapidly than MDS/AML.

t(8;21) prior to acute leukemia

A t(8;21)(q22;q22) without blood and bone marrow invasion by immature myeloid precursor cells occurred in a patient previously treated for polycythemia vera. The presence of a molecular rearrangement confirmed that the chromosomal abnormality was identical to that observed in acute leukemia with t(8;21). This case shows that the translocation, t(8;21), may occur in myelodysplasia and suggests that it can precede the appearance of overt leukemia.