Chromosomal characteristics of chronic and blastic phase of chronic myeloid leukemia. A study of 100 patients in India

NPM1 Mutated, BCR-ABL1 Positive Myeloid Neoplasms: Review of the Literature

Breakpoint cluster region - Abelson (BCR-ABL1) chimeric protein and mutated Nucleophosmin (NPM1) are often present in hematological cancers, but they rarely coexist in the same disease. Both anomalies are considered founder mutations that inhibit differentiation and apoptosis, but BCR-ABL1 could act as a secondary mutation conferring a proliferative advantage to a pre-neoplastic clone. The 2016 World Health Organization (WHO) classification lists the provisional acute myeloid leukemia (AML) with BCR-ABL1, which must be diagnosed differentially from the rare blast phase (BP) onset of chronic myeloid leukemia (CML), mainly because of the different therapeutic approach in the use of tyrosine kinase inhibitors (TKI). Here we review the BCR/ABL1 plus NPMc+ published cases since 1975 and describe a case from our institution in order to discuss the clinical and molecular features of this rare combination, and report the latest acquisition about an occurrence that could pertain either to the rare AML BCR-ABL1 positive or the even rarer CML-BP with mutated NPM1 at the onset. Differential diagnosis is based on careful analysis of genotypic and phenotypic features and anamnestic, clinical evolution, and background data. Therapeutic decisions must consider the broader clinical aspects, the comparatively mild effects of TKI therapy versus the great benefit that might bring to most of the patients, as may be incidentally demonstrated by our case history.

Cytogenetic & molecular analyses in adult chronic myelogenous leukaemia patients in north India

Background & objectives:

Chronic myelogenous leukaemia (CML) is the commonest leukaemia in Asia. There is a paucity data on cytogenetic and molecular analyses of Indian CML patients. This apparently reflects the low availability of cytogenetic and molecular techniques in our country. This study aimed to document various types of BCR-ABL fusion transcripts in different phases of CML and to compare the Ph chromosome positivity/negativity vis-a-vis BCR-ABL fusion transcripts in adult CML patients.

Methods:

Between June 2004 and February 2009, 208 patients were diagnosed as CML in chronic phase (CP), accelerated phase (AP) and blast crisis (BC), according to standard criteria. Cytogenetic and molecular genetic analyses were performed in all patients. Various types of BCR-ABL hybrid transcripts were compared with phases of CML and cytogenetic abnormalities.

Results:

Among 208 CML patients, b3a2 BCR-ABL transcripts were most commonly detected (66.82%) followed by b2a2 (28.84%), b3a2 + b2a2 (3.36%), b3a2 + e19a2 (0.48%) and b2a2 + e19a2 (0.48%). b3a2 transcripts were more frequently detected than b2a2 transcripts, in the whole group of 208 as well as in 183 CML-CP patients (P<0.0001). Ph chromosome was positive in 135 of 139 patients with b3a2 transcripts and 56 of 60 patients with b2a2 transcripts, difference not being significant. Additional cytogenetic abnormalities detected in 3.8 per cent patients in CML-CP and 44 per cent patients in CML-AP/BC, did not show predilection for any BCR-ABL transcript type.

Interpretation & conclusions:

This study documents higher Ph positivity (96.15%) by cytogenetic analysis among CML patients, as confirmed by qualitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis in a large patient group from north India. Both the techniques contribute towards understanding the disease biology, and have important implications for diagnosis and management of CML patients.

Characterization of cryptic rearrangements, deletion, complex variants of PML, RARA in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is characterized by a reciprocal translocation t(15;17)(q22;q21) leading to the disruption of Promyelocytic leukemia (PML) and Retionic Acid Receptor Alpha (RARA) followed by reciprocal PML–RARA fusion in 90% of the cases. Fluorescence in situ hybridization (FISH) has overcome the hurdles of unavailability of abnormal and/or lack of metaphase cells, and detection of cryptic, submicroscopic rearrangements. In the present study, besides diagnostic approach we sought to analyze these cases for identification and characterization of cryptic rearrangements, deletion variants and unknown RARA translocation variants by application of D-FISH and RARA break-apart probe strategy on interphase and metaphase cells in a large series of 200 cases of APL. Forty cases (20%) had atypical PML–RARA and/or RARA variants. D-FISH with PML/RARA probe helped identification of RARA insertion to PML. By application of D-FISH on metaphase cells, we documented that translocation of 15 to 17 leads to 17q deletion which results in loss of reciprocal fusion and/or residual RARA on der(17). Among the complex variants of t(15;17), PML–RARA fusion followed by residual RARA insertion closed to PML–RARA on der(15) was unique and unusual. FISH with break-apart RARA probe on metaphase cells was found to be a very efficient strategy to detect unknown RARA variant translocations like t(11;17)(q23;q21), t(11;17)(q13;q21) and t(2;17)(p21;q21). These findings proved that D-FISH and break-apart probe strategy has potential to detect primary as well as secondary additional aberrations of PML, RARA and other additional loci. The long-term clinical follow-up is essential to evaluate the clinical importance of these findings.

Persistence of derivative chromosome 22 after achieving a major molecular response in chronic myeloid leukemia with a cryptic BCR-ABL1 fusion gene

We herein report the findings of a 47-year-old Japanese female with chronic myeloid leukemia (CML) with a cryptic BCR-ABL1 transcript on chromosome 9 and a derivative chromosome 22 unrelated to BCR-ABL1. Although she achieved and continued to demonstrate a major molecular response to imatinib treatment following interferon-alpha, there was persistence of a derivative chromosome 22. A detailed chromosome/molecular studies, including serial karyotyping analysis, finally resulted in the karyotyping at the disease onset to be 47,XX,+del(22)(q11.2), with two genetic evens, namely a cryptic BCR-ABL1 transcript on chromosome 9 and derivative chromosome 22 unrelated to BCR-ABL1. This CML case with these two rare genetic events thus raises diagnostic issues such as the difficulty in making a concise evaluation of the chromosomal/molecular events and an accurate disease prognosis, as well as the difficulty in determining the disease remission status after treatment.

A complex translocation (9;22;16)(q34;q11.2;p13) in chronic myelocytic leukemia

The t(9;22) is present in almost all cases with chronic myelocytic leukemia (CML). Around 5% of these patients show complex translocations involving a third chromosome in addition to chromosomes 9 and 22. All chromosomes have participated in these variants and the BCR-ABL1 hybrid gene is always present. We describe a CML case with a new complex t(9;22;16)(q34;q11.2;p13). Seven months after imatinib treatment a karyotype showed the appearance of a clone with a standard t(9;22) in addition to the clone with the complex translocation. The b3a2 transcript of BCR-ABL1 was detected both at diagnosis and 7 months after therapy. In CML, both complex translocations and standard translocations have the same prognosis. However, these complex variants could contribute to the tumoral evolution by conferring selective advantages that, in turn, cause the preferential manifestation at diagnosis of clones with complex translocations.

A fluorescence in situ hybridization study of complex t(9;22) in two chronic myelocytic leukemia cases with a masked Philadelphia chromosome

The t(9;22)(q34;q11) is evident in more than 90% of patients with chronic myelocytic leukemia (CML) and gives rise to the Philadelphia chromosome (Ph). Approximately 5%-10% of CML patients show variant translocations involving other chromosomes in addition to chromosomes 9 and 22. In some variant translocations, additional material is transferred on der(22), resulting in a masked Ph chromosome. In this paper, we report two apparently Ph-negative (Ph-) CML cases showing a t(7;9;22)(q22;q34;q11) and a t(8;9;22)(q12;q34;q11), respectively. A detailed molecular cytogenetic characterization was performed by fluorescence in situ hybridization (FISH), which disclosed the presence of the 5'BCR/3'ABL fusion gene on the der(7) and der(8) chromosomes, respectively. Derivative (22) appeared as a masked Ph chromosome in both cases. FISH analysis with appropriate BAC/PAC clones allowed us to precisely characterize the complex chromosomal rearrangements that were not detected by conventional cytogenetic analysis.

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.

Myelodysplasia and the leukemias

The armistice after World War II marked the beginning of an era that was to last to the end of the present century. It was an era in which many changes in medicine and nursing combined to alter the entire philosophy of managing malignant disease. More specifically, the fluid-phase tumors, which comprise myelodysplasia and the leukemias, were singled out for special attention. First there was the ease with which blood and bone marrow could be sampled, making serial investigations simple and practical. Second, cytotoxic drugs became available ranging from nitrogen mustard through cytosine arabinoside, the anthracycline antibiotics, and the epi-podophyllotoxins. Although cytomorphology of the hematopoietic tissue had been exquisitely defined with the use of Romanowsky stains coupled with electron microscopy, the diagnosis of leukemia was, before 1945, a death sentence for want of effective therapy. This changed dramatically with the introduction of the folate antagonists, and progress was unremitting as the range of new products expanded. Suddenly responses could be obtained with single agents, and fairly rapidly combinations were developed for cumulative antitumor effect. Many agents had undesirable toxicity among different organs. Although slightly different for myeloblastic or lymphoblastic variants, this approach produced apparent disease eradication. The concept of complete remission, both clinical and hematologic, was born. Some of our early enthusiasm has had to be tempered with the somber appreciation that not all patients can improve and many others experience relapses. Where then do we stand? Leukemic cells themselves seldom kill. It is the relentless and uncontrolled expansion of a neoplastic clone that leads to bone marrow failure, albeit at different rates in the various subtypes. In the acute forms, the common presentation remains symptomatic anemia, neutropenic sepsis, and thrombocytopenic bleeding. Differentiation from marrow aplasia may not be possible at first on clinical grounds, although bone tenderness, gingival hypertrophy, and skin infiltration are among the general useful differential signs. Findings in the circulation and the marrow are of cardinal importance in diagnosis; they provide the basis for classification. Improved accuracy has followed the introduction of cytochemical stains, and a widening range of monoclonal antibodies, and greater recourse to karyotyping, have enhanced diagnostic acumen. Treatment decisions rest on many variables or prognostic factors that include age, performance status, comorbidity, and disease category, with an ever increasing regard for the part played by cellular and molecular genetics. Despite skillful utilization of this wealth of information for optimal management, outcome often leaves much to be desired. Myelodysplasia encompasses a number of different syndromes in which the refractory anemias are indolent, whereas those with excess blasts progress toward overt leukemia. Considerable judgment is necessary in selecting patients for whom supportive therapy alone is appropriate and recognizing others, up to one third of patients for whom use growth factors that include erythropoietin, granulocyte or granulocyte monocyte-colony stimulating factors, and thrombopoietin can be justified. The often unfavorable result has been a stimulus to current investigations that examine the value of intensive chemotherapy or the more innovative bone marrow transplantation and its peripheral blood equivalent. Autografting is a newer alternative that does not have proved potential. Acute leukemia, whether myeloblastic or lymphoblastic, has been managed with mixed success. Remission rates have steadily increased and, notably among children, moved toward 100% in certain groupings. The downside of nonspecific drug regimens is that some patients simply may not respond, whereas others experience remissions and then relapses. (ABSTRACT TRUNCATED)

Development of Ph positive chronic myeloid leukemia in a patient with chronic lymphocytic leukemia treated with total body irradiation: a rare association

Philadelphia (ph) chromosome positive chronic myeloid leukemia developed in a patient treated for chronic lymphocytic leukemia after treatment with total body irradiation. The role of radiation in the development of CML is discussed.

Karyotypic findings as an independent prognostic marker in chronic myeloid leukaemia blast crisis

Fifty-three patients with Ph positive chronic myeloid leukaemia in blastic phase were studied. Additional abnormalities were found in 29 (55%) patients and were more common in myeloid (64%) than lymphoid (45%) blast crisis. The most frequent were +Ph (32%), +8 (28%), +19 (19%), +20 (9%) and +21 (9%). i(17q) (9%) was associated with thrombocytopenia (5/5) and basophilia (2/5). The incidence of additional abnormalities was higher in patients treated with busulphan (70%) than hydroxyurea (44%). No significant differences were noted in the mean values of the clinical and haematological findings recorded at blast crisis between patients with only Ph positive (PP) cells and those with additional abnormalities (AP + AA). Univariate analysis identified karyotypic findings as an independent prognostic marker indicating its significance in assessing the response to therapy and survival after the onset of transformation.

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

Chromosome analysis of bone marrow (BM) aspirate from a 36-year-old man with chronic myeloid leukemia (CML) in blastic phase (BP) showed a four-break rearrangement t(11;9)(9;22)(q23; p22q34;q11), which can be considered a t(9;22)(q34;q11) and a secondary t(9;11)(p22;q23). It is not surprising that additional chromosome abnormalities occur in patients with Ph-positive CML in BP, but it is of interest that t(9;11)(p22;q23), characteristic of acute myeloid leukemia French-American-British (FAB) type M5 (ANLL-M5) was observed. The possible meaning of this additional change in BP of CML is discussed.