Blastic phase chronic myeloid leukemia with a four-break rearrangement: t(11;9)(9;22)(q23;p22q34;q11)

An unusual translocation, t(1;11)(q21;q23), in a case of chronic myeloid leukemia with a cryptic Philadelphia chromosome

Chronic myeloid leukemia (CML) is characterized by the translocation t(9;22)(q34;q11) [Philadelphia (Ph) chromosome). Although not frequently occurring, additional chromosome abnormalities (ACAs) can be detected at diagnosis and a number have been associated with an adverse cytogenetic and molecular outcome. The present study reports a case of CML presenting with the translocation t(1;11)(q21;q23) and a cryptic Ph chromosome. The presence of ACAs could generate greater genetic instability, promoting the emergence of further alterations. The present findings suggest that t(1;11)(q21;q23) can prevent a good response to tyrosine kinase inhibitor (TKI) therapy developing a primary resistance. In the present patient, at a recent follow-up, the T315I mutation was detected. This mutation confers full resistance to all available TKI, except ponatinib, which was not a therapeutic option due to comorbidities.

Chromosomal rearrangement involving 11q23 locus in chronic myelogenous leukemia: a rare phenomenon frequently associated with disease progression and poor prognosis

Background

Progression of chronic myelogenous leukemia (CML) is frequently accompanied by cytogenetic evolution, commonly unbalanced chromosomal changes, such as an extra copy of Philadelphia chromosome (Ph), +8, and i(17)(q10). Balanced chromosomal translocations typically found in de novo acute myeloid leukemia occur occasionally in CML, such as inv(3)/t(3;3), t(8;21), t(15;17), and inv(16). Translocations involving the 11q23, a relatively common genetic abnormality in acute leukemia, have been seldom reported in CML. In this study, we explored the prevalence and prognostic role of 11q23 in CML.

Methods

We searched our pathology archives for CML cases diagnosed in our institution from 1998 to present. Cases with 11q23 rearrangements were retrieved. The corresponding clinicopathological data were reviewed.

Results

A total of 2,012 cases of CML with available karyotypes were identified. Ten (0.5%) CML cases had 11q23 rearrangement in Ph-positive cells, including 4 cases of t(9;11), 2 cases of t(11;19), and 1 case each of t(2;11), t(4;11), t(6;11), and t(4;9;11). Eight cases (80%) had other concurrent chromosomal abnormalities. There were 6 men and 4 women with a median age of 50 years (range, 21–70 years) at time of initial diagnosis of CML. 11q23 rearrangement occurred after a median period of 12.5 months (range, 0–172 months): 1 patient in chronic phase, 2 in accelerated phase, and 7 in blast phase. Eight of ten patients died after a median follow-up of 16.5 months (range, 8–186 months) following the initial diagnosis of CML, and a median of 6.7 months (range, 0.8–16.6 months) after the emergence of 11q23 rearrangement. The remaining two patients had complete remission at the last follow-up, 50.2 and 6.9 months, respectively. In addition, we also identified a case with 11q23/t(11;17) in Ph-negative cells in a patient with a history of CML. MLL involvement was tested by fluorescence in situ hybridization in 10 cases, and 7 cases (70%) were positive.

Conclusions

In summary, chromosomal rearrangements involving 11q23 are rare in CML, frequently occurring in blast phase, and are often associated with other cytogenetic abnormalities. These patients had a low response rate to tyrosine kinase inhibitors and a poor prognosis.

Acute monocytic leukemia with coexpression of minor BCR-ABL1 and PICALM-MLLT10 fusion genes along with overexpression of HOXA9

The t(9;22)(q34;q11) translocation occurs in chronic myeloid leukemia (CML) and adult B-cell acute lymphoblastic leukemia (ALL), leading to fusion of BCR to ABL1 and constitutive activation of ABL1 tyrosine kinase activity. The main BCR-ABL1 breakpoints result in P190 BCR-ABL1 or P210 BCR-ABL1 fusion proteins. The latter is found in almost all cases of CML and in one third of the cases of t(9;22)-positive adult B-ALL. P190 BCR-ABL1 is found in the remaining two thirds of t(9;22)-positive adult B-ALL cases but only exceptionally in CML. We describe here the first case of t(9;22)(q34;q11) associated with t(10;11)(p13;q14) in acute monocytic leukemia. The recurrent t(10;11)(p13;q14) translocation, usually found in acute myeloid leukemia (AML) and T-ALL, merges PICALM to MLLT10. RT-PCR enabled identification of PICALM-MLLT10 and BCR-ABL1 e1-a2 fusion transcripts; in the context of chronic and acute myeloid leukemia, the latter usually has a monocytic presentation. We also identified overexpression of HOXA9, a gene essential to myeloid differentiation that is expressed in PICALM-MLLT10 and MLL-rearranged acute leukemias. This case fits with and extends a recently proposed multistage AML model in which constitutive activation of tyrosine kinases by mutations (BCR-ABL1) are associated with deregulation of transcription factors central to myeloid differentiation (HOXA9 secondary to PICALM-MLLT10).

“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.

Uncommon karyotypic abnormality, t(11;19)(q23;p13.3), in a patient with blastic phase of chronic myeloid leukemia

We describe unusual cytogenetic findings in a 33-year-old male with blastic phase of Philadelphia chromosome (Ph)-positive chronic myeloid leukemia. In addition to the t(9;22)(q34;q11), which was detected in all metaphases, a t(11;19)(q23;p13.3) was also identified as an evolutional change in all 20 metaphases. Fluorescence in situ hybridization (FISH) analysis showed that fusion signals of the ABL/BCR probes were found in 95% of blastic cells. Southern blotting and FISH analysis also revealed involvement of the MLL gene on 11q23. Clinical course was aggressive and the patient responded poorly to therapy. These findings suggest an association between Ph and 11q23 with poor prognosis, and that t(11;19)(q23;p13.3) was the essential pathogenic factor in our case.

Multicolor COBRA-FISH analysis of chronic myeloid leukemia reveals novel cryptic balanced translocations during disease progression

During the initial indolent chronic phase of chronic myeloid leukemia (CML), the t(9;22)(q34;q11), resulting in the Philadelphia chromosome (Ph), is usually the sole cytogenetic anomaly, but as the disease progresses into the accelerated phase (AP), and eventually into aggressive blast crisis (BC), secondary aberrations, mainly unbalanced changes such as +8, i(17q), and +Ph, are frequent. To date, molecular genetic studies of CML BC have mainly focused on alterations of well-known tumor-suppressor genes (e.g., TP53, CDKN2A, and RB1) and oncogenes (e.g., RAS and MYC), whereas limited knowledge is available about the molecular genetic correlates of the unbalanced chromosomal abnormalities. Balanced secondary changes are rare in CML AP/BC, but it is not known whether cryptic chromosomal translocations, generating fusion genes, may be responsible for disease progression in a subgroup of CML. To address this issue, we used multicolor combined binary ratio fluorescence in situ hybridization (FISH), which allows the simultaneous visualization of all 24 chromosomes in different colors, verified by locus-specific FISH in a series of 33 CML cases. Two cryptic balanced translocations, t(7;17)(q32-34;q23) and t(7;17)(p15;q23), were found in two of the five cases showing the t(9;22) as the only cytogenetic change. Using several BAC clones, the breakpoints at 17q23 in both cases were mapped within a 350-kb region. In the case with the 7p15 breakpoint, a BAC clone containing the HOXA gene cluster displayed a split signal, suggesting a possible creation of a fusion gene involving a member of the HOXA family. Furthermore, one case with a partially cryptic t(9;11)(p21-22;q23) and an MLL rearrangement as well as a previously unreported t(3;10)(p22;p12-13) were identified. Altogether, a refined karyotypic description was achieved in 12 (36%) of the 33 investigated cases, illustrating the value of using multicolor FISH for identifying pathogenetically important aberrations in CML AP/BC.

Additional t(11;17)(q23;q21) in a patient with Philadelphia-positive mixed lineage antigen-expressing leukemia

We describe very uncommon phenotypic and cytogenetic findings in a 40-year-old female with blast phase of Philadelphia chromosome (Ph)-positive CML. In addition to the t(9;22)(q34;q11) that was detected in all metaphases, a t(11;17)(q23;q21) was identified in 15 of 20 metaphases. Reverse transcription-polymerase chain reaction showed the major and minor bcr/abl fusion transcripts in the cells from a bone marrow (BM) sample. Fluorescence in situ hybridization (FISH) analysis also showed that fusion signals of the bcr and abl probes were found in 95% of blastic cells and in 64% of neutrophils. MLL gene rearrangement was also detected in some blastic cells but not in neutrophils by FISH analysis. Phenotypically, blastic cells expressed mixed lineage antigens such as CD34, CD33, CD13, CD19, CD7, and CD41. Immunogenotypically, some population of BM cells showed monoclonal rearrangements of immunoglobulin heavy chain and T-cell receptor gamma chain genes by Southern blot analysis. Clinical course was aggressive, and therapy was poorly tolerated. Such findings seem to support an association between Ph and an abnormality of 11q23 with poor prognosis, and suggest that the expression of both abnormal genes may be related to this mixed lineage antigen-expressing leukemia.

Fluorescence in situ hybridization analysis of complex translocations in two newly diagnosed Philadelphia chromosome-positive chronic myelogenous leukemia patients

Two different complex translocations from newly diagnosed cases of Philadelphia chromosome-positive chronic myelogenous leukemia (CML) were characterized by G-banding and fluorescence in situ hybridization (FISH) analysis. In one case, a unique balanced t(9;22;9;11) (q34;q11;p22;q23) was identified by G-banding, and confirmed by FISH using MBCR/ABL and painting probes. In the second case, an apparently balanced t(19;22) was identified by G-banding analysis. FISH using MBCR/ABL probe detected the fusion gene on the derivative chromosome 22, indicating the involvement of chromosome 9. Further FISH analysis with selected painting probes showed that the t(19;22) was a result of a complex translocation involving chromosomes 9, 19, 21, and 22.

Unusual clinical course and acquisition of del(11)(q23) in second lymphatic blastic phase of a Ph-positive chronic myeloid leukemia

We describe unusual clinical and cytogenetic findings of a 29-year-old female with a Philadelphia chromosome (Ph)-positive chronic myeloid leukemia (CML), who showed a mosaic of apparently normal cells and cells bearing the classical t(9;22)(q34;q11) during the first lymphatic blastic phase (BP). The second lymphatic BP developed 10 years later. In addition to the t(9;22), which was detected in all metaphases, a del(11)(q23) was identified as a subclonal change in 4 of 25 metaphases. Fluorescence in situ hybridization (FISH) analysis using a chromosome 11-specific library probe and a probe covering the breakpoint cluster region of the MLL gene revealed hybridization signals of both probes on the normal and the deleted chromosome 11, indicating that the breakpoint on chromosome 11 occurred telomerically to the breakpoint cluster region of the MLL gene. Chemotherapeutic treatment resulted in reconstitution of the chronic phase with persistence of the Ph translocation as the sole chromosomal abnormality.