The karyotype of blastic crisis

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.

Management of CML-blast crisis

Tyrosine kinase inhibitors (TKI) have moderately improved survival in BC, but a median survival of less than 1 year is still unsatisfactory. This article reviews the various tests required for diagnosis of BC, features at diagnosis, treatment modalities (intensive chemotherapy, TKI, allo-SCT and a selection of investigational agents), options of prevention and predictors of progression. The best prognosis is observed in patients that achieve a 2nd CP. Allo-SCT probably further improves prognosis of patients in 2nd CP. The choice of TKI should be directed by the mutation profile of the patient. BC can be prevented. A careful analysis of risk factors for progression may help. Current treatment options are combined in a concluding strategy for the management of BC.

Case of CML lymphoid blast crisis presenting as bilateral breast masses

A woman aged 42 years with a 1-month history of rapidly expanding bilateral breast masses presented with severe leucocytosis, anaemia, blurry vision, headaches and shortness of breath. Evaluation revealed chronic myeloid leukaemia in lymphoid blast crisis with extramedullary leukaemia involving her breasts.

Simplifying procedure for prediction of resistance risk in CML patients - Test of sensitivity to TKI ex vivo

Tyrosine kinase inhibitors (TKIs) targeting BCR-ABL have dramatically improved chronic myeloid leukemia therapy. While imatinib remains to be the first line therapy, about 30% of patients develop resistance or intolerance to this drug and are recommended to switch to other TKIs. Nilotinib and dasatinib are currently implemented into the first line therapy and other inhibitors have already entered the clinical practice. This opens further questions on how to select the best TKI for each patient not only during the therapy but also at diagnosis. The individualized therapy concept requires a reliable establishment of prognosis and prediction of response to the available TKIs. We tested the ex vivo sensitivity of patient primary leukocytes to imatinib, nilotinib and dasatinib - two concentrations of each inhibitor for 48h incubation - and we evaluated the usefulness of such tests for the clinical practice. Besides reflecting the actual sensitivity to the therapy, our optimized simple tests were able to predict the outcome in 90/87% of patients, for the next 12/24months, respectively. According to these results, the presented ex vivo testing could help clinicians to select the appropriate drug for each patient at diagnosis and also at any time of the therapy.

HCVAD plus imatinib or dasatinib in lymphoid blastic phase chronic myeloid leukemia

BACKGROUND

Chronic myeloid leukemia (CML) may progress to blast phase (BP) at the rate of 1% to 1.5% per year. With the use of single-agent tyrosine kinase inhibitors, median overall survival ranges between 7 and 11 months.

METHODS

The outcome was analyzed for 42 patients with lymphoid BP-CML who were treated with hyperfractionated cyclophosphamide, vincristine, Adriamycin, dexamethasone (HCVAD) plus imatinib or dasatinib.

RESULTS

Complete hematological response was achieved in 90% of patients, complete cytogenetic remission in 58%, and complete molecular remission in 25%. Flow cytometry minimal residual disease negativity was achieved by 42% of evaluable patients after induction. Eighteen patients received allogeneic stem cell transplant (SCT) while in first complete hematological response. Median remission duration was 14 months and was longer among SCT recipients (P = .01) on multivariate analysis. Median overall survival was 17 months (range, 7-27 months) and was longer among SCT recipients (P < .001) and patients treated with dasatinib (P = .07) on multivariate analysis. Although a high rate of hematologic toxicity (100%) and infectious complications (59%) were observed, the related rate of treatment discontinuation was low (7% and 9%, respectively).

CONCLUSIONS

HCVAD combined with tyrosine kinase inhibitors is an effective regimen for the management of BP-CML, particularly when followed by allogeneic SCT.

How I treat CML blast crisis

Blast crisis (BC) remains the major challenge in the management of chronic myeloid leukemia (CML). It is now generally accepted that BC is the consequence of continued BCR-ABL activity leading to genetic instability, DNA damage, and impaired DNA repair. Most patients with BC carry multiple mutations, and up to 80% show additional chromosomal aberrations in a nonrandom pattern. Treatment with tyrosine kinase inhibitors has improved survival in BC modestly, but most long-term survivors are those who have been transplanted. Patients in BC should be treated with a tyrosine kinase inhibitor according to mutation profile, with or without chemotherapy, with the goal of achieving a second chronic phase and proceeding to allogeneic stem cell transplantation as quickly as possible. Although long-term remissions are rare, allogeneic stem cell transplantation provides the best chance of a cure in BC. Investigational agents are not likely to provide an alternative in the near future. In view of these limited options, prevention of BC by a rigorous and early elimination of BCR-ABL is recommended. Early response indicators should be used to select patients for alternative therapies and early transplantation. Every attempt should be made to reduce or eliminate BCR-ABL consistent with good patient care as far as possible.

Fusion tyrosine kinases: a result and cause of genomic instability

Reciprocal chromosomal translocations may arise as a result of unfaithful repair of spontaneous DNA double-strand breaks, most probably induced by oxidative stress, radiation, genotoxic chemicals and/or replication stress. Genes encoding tyrosine kinases are targeted by these mechanisms resulting in the generation of chimera genes encoding fusion tyrosine kinases (FTKs). FTKs display transforming activity owing to their constitutive kinase activity causing deregulated proliferation, apoptosis, differentiation and adhesion. Moreover, FTKs are able to facilitate DNA repair, prolong activation of G(2)/M and S cell cycle checkpoints, and elevate expression of antiapoptotic protein Bcl-X(L), making malignant cells less responsive to antitumor treatment. FTKs may also stimulate the generation of reactive oxygen species and enhance spontaneous DNA damage in tumor cells. Unfortunately, FTKs compromise the fidelity of DNA repair mechanisms, which contribute to the accumulation of additional genetic abnormalities leading to the resistance to inhibitors such as imatinib mesylate and malignant progression of the disease.

Genomewide screening of DNA copy number changes in chronic myelogenous leukemia with the use of high-resolution array-based comparative genomic hybridization

Chronic myelogenous leukemia (CML) evolves from an indolent chronic phase (CP) characterized by the Philadelphia chromosome. Without effective therapy, it progresses to an accelerated phase (AP) and eventually to a fatal blast crisis (BC). To identify the genes involved in stage progression in CML, we performed a genomewide screening of DNA copy number changes in a total of 55 CML patients in different stages with the use of the high-resolution array-based comparative genomic hybridization (array CGH) technique. We constructed Human 1M arrays that contained 3,151 bacterial artificial chromosome (BAC) DNAs, allowing for an average resolution of 1.0 Mb across the entire genome. In addition to common chromosomal abnormalities, array CGH analysis unveiled a number of novel copy number changes. These alterations included losses in 2q26.2-q37.3, 5q23.1-q23.3, 5q31.2-q32, 7p21.3-p11.2, 7q31.1-q31.33, 8pter-p12(p11.2), 9p, and 22q13.1-q13.31 and gains in 3q26.2-q29, 6p22.3, 7p15.2-p14.3, 8p12, 8p21.3, 8p23.2, 8q24.13-q24.21, 9q, 19p13.2-p12, and 22q13.1-q13.32 and occurred at a higher frequency in AP and BC. Minimal copy number changes affecting even a single BAC locus were also identified. Our data suggests that at least a proportion of CML patients carry still-unknown cryptic genomic alterations that could affect a gene or genes of importance in the disease progression of CML. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat.

Interphase FISH screening for the LCR-mediated common rearrangement of isochromosome 17q in primary myelofibrosis

Non-allelic homologous recombination (NAHR) between low-copy repeats (LCRs) has been implicated recently in somatic rearrangements including isochromosome i(17q), which is associated with hematologic malignancies as well as solid tumors. In hematological malignancies, the most common i(17q) breakpoint results from LCR-mediated NAHR, which creates a dicentric chromosome, idic(17)(p11.2). We report an elderly patient who presented with primary myelofibrosis (MF) with myeloid metaplasia (MMM), associated with idic(17)(p11.2) as the sole chromosomal abnormality, making this the first idic(17)(p11.2) myeloproliferative case reported in which the breakpoints are mapped to the breakpoint cluster region in proximal 17p. The rearrangement breakpoint maps to the previously defined LCR cluster, further suggesting that the genomic architecture of proximal 17p may be responsible for the formation of the majority of i(17q) cases. We describe our development of a rapid screening test using interphase FISH to detect idic(17)(p11.2), discuss the potential prognostic value of this molecular diagnostic test, and examine the relevance of LCR-mediated NAHR to common rearrangements in neoplasms.

Distribution of X-ray-induced chromosome breakpoints in Down syndrome lymphocytes

Down syndrome (DS) individuals are known to be predisposed to develop leukemia and their lymphocytes are highly sensitive to the induction of chromosome aberrations by X-rays. A study was conducted to identify the chromosome breakpoints and to evaluate whether site specificity for chromosome breakage and rearrangement may exist which may explain the predisposition phenomenon. DS lymphocytes at the G1 phase of the cell cycle were irradiated with 300, 450, and 600 rad of X-rays. Cells were harvested after 3 days in culture and 193 G-banded karyotypes were analyzed to identify the induced chromosome abnormalities. Out of 273 breakpoints identified, 122 were involved in the formation of stable chromosome rearrangements and 151 in the formation of unstable abnormalities. The Poisson analysis of these breakpoints demonstrated that 16 chromosome bands located in chromosomes 1, 3, 7, 12, 17, 19 and X were preferentially involved in breakage and rearrangement (P less than 0.05). These 16 bands are also found to be locations of "cancer breakpoints," oncogenes, or fragile sites. Many abnormal cells were observed to carry stable chromosome rearrangements only. Therefore, these cells are presumed to be compatible with survival and to be "initiated" in the transformation process. We propose that similar stable and site-specific chromosome rearrangements may exist in proliferating cells in DS individuals after exposure to clastogens and that this abnormality predisposes them to develop leukemia.

Chronic myelogenous leukemia as a paradigm of early cancer and possible curative strategies

The chronological history of the important discoveries leading to our present understanding of the essential clinical, biological, biochemical, and molecular features of chronic myelogenous leukemia (CML) are first reviewed, focusing in particular on abnormalities that are responsible for the massive myeloid expansion. CML is an excellent target for the development of selective treatment because of its highly consistent genetic abnormality and qualitatively different fusion gene product, p210(bcr-abl). It is likely that the multiple signaling pathways dysregulated by p210(bcr-abl) are sufficient to explain all the initial manifestations of the chronic phase of the disease, although understanding of the circuitry is still very incomplete. Evidence is presented that the signaling pathways that are constitutively activated in CML stem cells and primitive progenitors cooperate with cytokines to increase the proportion of stem cells that are activated and thereby increase recruitment into the committed progenitor cell pool, and that this increased activation is probably the primary cause of the massive myeloid expansion in CML. The cooperative interactions between Bcr-Abl and cytokine-activated pathways interfere with the synergistic interactions between multiple cytokines that are normally required for the activation of stem cells, while at the same time causing numerous subtle biochemical and functional abnormalities in the later progenitors and precursor cells. The committed CML progenitors have discordant maturation and reduced proliferative capacity compared to normal committed progenitors, and like them, are destined to die after a limited number of divisions. Thus, the primary goal of any curative strategy must be to eliminate all Philadelphia positive (Ph+) primitive cells that are capable of symmetric division and thereby able to expand the Ph+ stem cell pool and recreate the disease. Several highly potent and moderately selective inhibitors of Bcr-Abl kinase have recently been discovered that are capable of killing the majority of actively proliferating early CML progenitors with minimal effects on normal progenitors. However, like their normal counterparts, most of the CML primitive stem cells are quiescent at any given time and are relatively invulnerable to the Bcr-Abl kinase inhibitors as well as other drugs. We propose that survival of dormant Ph+ stem cells may be the most important reason for the inability to cure the disease during initial treatment, while resistance to the inhibitors and other drugs becomes increasingly important later. An outline of a possible curative strategy is presented that attempts to take advantage of the subtle differences in the proliferative behavior of normal and Ph+ stem cells and the newly discovered selective inhibitors of Bcr-Abl. Leukemia (2003) 17, 1211-1262. doi:10.1038/sj.leu.2402912

A study on the incidence of ABL gene deletion on derivative chromosome 9 in chronic myelogenous leukemia by interphase fluorescence in situ hybridization and its association with disease progression

Fluorescence in situ hybridization for the BCR/ABL rearrangement in 138 bone marrow specimens from 59 Philadelphia(+) (Ph(+)) chronic myelogenous leukemia (CML) patients, 35 Ph(+) acute lymphoblastic leukemia (ALL) patients, and 57 Ph(-) ALL patients was used. Sixteen (27.1%) of the 59 CML patients had deletions of the residual ABL gene on the derivative chromosome 9. During the study period, 32 of the 59 CML patients progressed to blast crisis or accelerated phase. Of these, nine patients had residual ABL gene deletions on the derivative chromosomes 9 and 23 patients had no deletions. The mean duration from first diagnosis to blast crisis or accelerated phase for the nine patients with ABL deletions was 32.8 months, and for the 23 patients without ABL deletions, it was 62.4 months (P = 0.017). The overall survival time for the 16 patients with deletions was 32.8 months, and for the 43 patients without deletions, it was 60.1 months (P = 0.164). ABL deletions were not detected among the 35 ALL patients (17 with major BCR/ABL, 18 with minor BCR/ABL), and it appears that this deletion occurs rarely or not at all in Ph(+) ALL patients, which is in contrast to the CML patients (27.1%). However, we detected two ALL cases with ABL deletion but without BCR/ABL rearrangement among 49 Ph(-) ALL and 66 Ph(-) AML patients. In conclusion, patients with ABL deletions progress to blast crisis or accelerated phase in a significantly shorter time than do those without such deletions. It is therefore suggested that the ABL deletion is an indicator of a poor prognosis in CML.

Chronic basophilic leukemia: a distinct clinico-pathologic entity?

OBJECTIVE

We sought to better define a group of rare and poorly understood myeloproliferative disorders that are characterized by prominent chronic basophilia in the absence of the Philadelphia chromosome (Ph) or its molecular equivalent.

METHODS

We screened our institution's electronic database from 1975 onwards, and identified four such cases. Clinical data and bone marrow pathology were carefully reviewed for these patients.

RESULTS

Two patients had prominent manifestations of basophil mediator-release and another presented with pituitary dysfunction. Bone marrow examination uniformly revealed trilineage hyperplasia with basophilia and eosinophilia, dysplastic megakaryocytic hyperplasia, and the absence of megakaryocyte clustering. An abnormal pattern of atypical mast cells was noted in two cases. While disease palliation was effectively achieved with hydroxyurea for one patient, transformation to acute myeloid leukemia was eventually observed in this case. Another patient has achieved long-term disease-free survival after undergoing allogeneic stem cell transplantation.

CONCLUSIONS

Our observations reveal a striking pathologic similarity among all four cases, and suggest this disease, which may be aggressive with the potential to transform into acute leukemia, to possibly represent a distinct clinico-pathologic entity (chronic basophilic leukemia).

BCR/ABL regulates response to DNA damage: the role in resistance to genotoxic treatment and in genomic instability

BCR/ABL regulates cell proliferation, apoptosis, differentiation and adhesion. In addition, BCR/ABL can induce resistance to cytostatic drugs and irradiation by modulation of DNA repair mechanisms, cell cycle checkpoints and Bcl-2 protein family members. Upon DNA damage BCR/ABL not only enhances reparation of DNA lesions (e.g. homologous recombination repair), but also prolongs activation of cell cycle checkpoints (e.g. G2/M) providing more time for repair of otherwise lethal lesions. Moreover, by modification of anti-apoptotic members of the Bcl-2 family (e.g. upregulation of Bcl-x(L)) BCR/ABL provides a cytoplasmic 'umbrella' protecting mitochondria from the 'rain' of apoptotic signals coming from the damaged DNA in the nucleus, thus preventing release of cytochrome c and activation of caspases. The unrepaired and/or aberrantly repaired (but not lethal) DNA lesions resulting from spontaneous and/or drug-induced damage can accumulate in BCR/ABL-transformed cells leading to genomic instability and malignant progression of the disease. Inhibition of BCR/ABL kinase activity by STI571 (Gleevec, imatinib mesylate) reverses drug resistance and, in combination with standard chemotherapeutics can exert strong anti-leukemia effect.

Factors affecting duration of survival after onset of blastic transformation of chronic myeloid leukemia

We analyzed factors having an impact on response to treatment and survival in 78 consecutive patients with chronic myeloid leukemia (CML) in blastic transformation (BT) referred to the Hammersmith Hospital from January 1995 to December 2000. BT was defined as the presence of at least 30% blasts in blood or marrow or extramedullary blastic deposits. Immunophenotyping of blasts showed 57 myeloid, 19 lymphoid, and 2 biphenotypic. The median age of the patients was 39.1 years (range, 11.3-73.4 years), with 55 males and 23 females. The median survival for all patients after onset of BT was 8.2 months (95% CI, 6.4-10). Patients in lymphoid BT survived longer than those in myeloid BT (median, 11.2 months versus 6.9 months, P =.052). Initial treatment varied; 41 patients received cytotoxic drugs, 8 underwent allogeneic or autologous transplantation procedures, 21 received STI571 (imatinib mesylate, Gleevec), 1 received radiotherapy, and 7 received no therapy. Of the 25 (32%) patients who achieved a "second chronic phase" with first therapy, 6 of 21 (29%) were treated with STI571 and 19 of 50 (38%) were treated with chemotherapy, transplantation, or radiotherapy. Patients who achieved a second chronic phase survived longer than those who did not (median time from onset of BT 12.0 months versus 6.3 months, P =.0004). In multivariate analysis the finding of more than 50% blast cells in the blood and the presence of cytogenetic progression were independent adverse prognostic variables for survival. We conclude that survival after onset of BT has improved in recent years but is still unsatisfactory. We speculate that the combined use of STI571 with cytotoxic drugs may offer additional benefit.

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.

17q21-qter trisomy is an indicator of poor prognosis in acute myelogenous leukemia

A reciprocal translocation (9;11) is often found in acute myeloid leukemia (AML), mostly of the M5a type. We report a case of a child with AML, in whom t(9;11) was observed at diagnosis as the sole structural abnormality, together with trisomies 19 and 21. The diagnosis was AML evolving from a myelodysplastic syndrome (MDS), and the blast morphology was undifferentiated. Chemotherapy failed to induce morphological remission and the patient's condition soon worsened. A subclone appeared and expanded during the course of the disease, with an additional unbalanced translocation (1;17) leading to trisomy of the long arm of chromosome 17 (17q). The data available from the literature on acquired anomalies involving 17q and our observation led us to postulate a specific link between the gain of 17q and complete chemoresistance.

Telomere dynamics and genetic instability in disease progression of chronic myeloid leukemia

Chronic myeloid leukemia (CML) is characterized by a Philadelphia (Ph) translocation creating a novel BCR-ABL oncoprotein, and CML patients have a chronic phase for several years followed by an intractable blast cell proliferation, called blast transformation. In the blast phase, more than 60% of patients show additional cytogenetic changes, e. g., double Ph, +8, i(17q). In this review, we would like to address genetic changes, including genome instability, cytogenetic changes, and telomere dynamics that relate to karyotypic instability. In the chronic phase, approximately 60% of CML patients show reduced telomere length without highly elevated telomerase activity or microsatellite alterations, indicating that telomere reduction may be linked to cell replication. Therefore, the Ph translocation might be a first event to immortalize cell proliferation. In the blast phase, 50% of CML patients have high levels of elevated telomerase activity and the same number of patients had microsatellite changes. Of note is that most patients with telomerase up-regulation in the blast phase had additional cytogenetic changes and >60% of them showed microsatellite changes at least at one locus. In contrast, most patients without telomerase activity did not show microsatellite changes. These findings may indicate that telomerase up-regulation in the blast phase of CML patients is closely associated with microsatellite changes (representative of genome instability), while blast cells in the remaining patients (30%) maintain their proliferative capability without microsatellite changes and telomerase up-regulation. This further suggests that there is also an unknown mechanism for genome stability without the process of telomerase up-regulation in some patients with CML in blast crisis.

Blast crisis of Ph-positive chronic myeloid leukemia with isochromosome 17q: report of 12 cases and review of the literature

Isochromosome 17q [i(17q)] is frequently observed in the blast crisis (BC) of chronic myelogenous leukemia (CML). It has been suggested that this chromosome abnormality is associated with special hematological characteristics of the BC, but the information on this subject is scarce. The clinical, hematological and cytogenetic features of patients with i(17q) were analyzed in a series of 121 patients with BC of Ph-positive CML. Twelve patients (10%) displayed an i(17q), representing the third commonest cytogenetic abnormality, after trisomy 8 and Ph chromosome duplication. In seven of the 12 patients the BC was preceded by an accelerated phase, and 10 had more than 10% blood basophils at BC diagnosis. The blast cells had a myeloid phenotype in the 12 patients. Five patients exhibited cytogenetic abnormalities in addition to i(17q), with trisomy 8 and duplication of the Ph chromosome being the alterations most frequently observed. Median survival of patients with i(17q) was 22 weeks, which was not significantly different from the survival of patients with myeloid BC in the overall series. These results are similar to the findings in 181 patients with i(17q) from 12 series of the literature, and confirm the special hematologic profile of BC of CML with this cytogenetic abnormality.

c-Myc antagonizes the effect of p53 on apoptosis and p21WAF1 transactivation in K562 leukemia cells

c-myc protooncogene positively regulates cell proliferation and overexpression of c-myc is found in many solid tumors and leukemias. In the present study we used the K562 human myeloid leukemia cell line as a model to study the functional interaction between c-Myc and p53. Using two different methods, we generated K562 transfectant cell lines with conditional expression of either c-Myc or p53. The cells expressed the p53Vall35 mutant, which adopts a wild-type conformation at 32 degrees C, while c-Myc induction was achieved with a zinc-inducible expression vector. We found that p53 in wild-type conformation induces growth arrest and apoptosis of K562. Expression of c-Myc significantly attenuated apoptosis and impaired the transcriptional activity of p53 on p21WAF1, Bax and cytomegalovirus promoters. The impairment of p21WAF1 transactivation by c-Myc was confirmed by transfection of a c-Myc-estrogen receptor fusion protein and by induction of c-myc by zinc in transfected cells. Also, p53-mediated up-regulation of p21WAF1 mRNA protein were significantly reduced by c-Myc, while Bax levels were unaffected. Consistently, c-Myc increased cyclin-dependent kinase 2 activity in K562 cells expressing p53 in wild-type conformation. These results suggest that c-Myc overexpression may antagonize the pro-apoptotic function of p53, thus providing a molecular mechanism for the frequently observed deregulation of c-myc in human cancer.

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.

Development of acute promyelocytic leukemia with isochromosome 17q after BCR/ABL positive chronic myeloid leukemia

We describe a pediatric case of acute promyelocytic leukemia with an i(17q) after treatment of BCR/ABL positive chronic myeloid leukemia (CML) for 3.5 years. The patient was treated with Busulphan, alpha-2a interferon, hydroxyurea, and cytosine arabinoside at various times in the course of the chronic phase of CML, because he had no HLA-identical donor for bone marrow transplantation. Hematologic remission was achieved for a short time, but cytogenetic remission was never possible. When promyelocytic blast crisis was diagnosed according to the French-American-British classification, cytogenetic studies revealed an i(17q) as a new feature in our patient. The promyelocytic transformation was associated with the appearance of an i(17q) preceding CML are discussed in the light of recent literature.

Diagnosis of acute basophilic leukemia

De novo acute basophilic leukemia (ABL) is a rare form of acute leukemia. Most frequently, the blast cells are morphologically undifferentiated, and the recognition of the presence of coarse basophilic granules may be the first step in diagnosis of this rare disorder. These granules are metachromatic and MPO negative. Immunophenotyping shows myeloid markers and some more specifically associated antigens such as CD9 or CD25 which are strongly expressed. Lymphoid, erythroid or megakaryocytic markers are not significantly expressed. In the absence of basophilic granules, some cases are classified as AML M0 if they express myeloid markers, or undifferentiated leukemia if no markers are present. If specific immature basophilic or theta granules are present, only an electron microscopic study will enable the diagnosis of a basophilic lineage assignment. Some cases may be misdiagnosed if all these steps are not followed. After all these investigations, two types of ABL may be defined: 1-A pure ABL, monophenotypic with basophilic lineage involvement alone, which should be classified as AML M8 . Genetic studies in these cases are very important for understanding the leukemic process and in a few cases, we can suspect c-MYB oncogene involvement but further investigations are still necessary. 2- More frequently, acute leukemia can be a mixture of blasts from different lineages with an important but variable participation of mature or immature basophilic cells. These cases must be classified as AML/Baso or multiphenotypic acute leukemias and often present Phl -chromosomal abnormality.

Promyelocytic blast crisis of chronic myelogenous leukaemia with translocations (9;22) and (15;17)

The promyelocytic blast crisis is a rare form of transformation during the evolution of chronic myeloid leukaemia (CML). We report a case of promyelocytic blast crisis with t(15;17) in addition to t(9;22). The morphology and immunophenotype of the blasts were similar to those seen in acute promyelocytic leukaemia (APL). The t(15;17) was confirmed by FISH. The patient had evidence of coagulopathy with clinical and laboratory findings of disseminated intravascular coagulation (DIC). This report highlights the importance of correlating the results of multiple diagnostic methods in order to establish a correct diagnosis of the promyelocytic blast crisis of CML.

Cytogenetic abnormalities related to histopathologic grade of astrocytic tumors

Cytogenetic analysis was performed on 7 low-grade astrocytomas, 10 anaplastic astrocytomas, and 14 glioblastomas. Abnormal chromosome numbers were noted in all cases of high-grade astrocytomas but were rarely noted in low-grade astrocytomas (28%). The most consistent changes in high-grade astrocytomas were complete loss of chromosome 10 (61%), gain of chromosome 7 (56%), and loss of chromosome 17 (28%). Certain structural abnormalities, such as marker chromosomes and double minutes (33%), and the deletion and translocation of chromosomes 1 (33%) and 17 (17%), were also noted. These results indicate that changes in the number and/or structure of chromosomes with related inactivation of tumor suppressor gene or oncogene activation might play a critical role in the formation and anaplastic progression of astrocytic tumors.

Leukemia breakpoint region in 3q21 is gene rich

Rearrangements of the long arm of human chromosome 3, including reciprocal translocations, inversions and deletion/duplication of bands 3q21-3q26, as well as deletions of 3q21 and reciprocal translocations between 3q21 and other chromosomes, are well documented in leukemia. Previous studies showed that the breakpoints within 3q21 cluster within a 10-40 kb region but no candidate genes were described. In this work, we have identified partial cDNAs corresponding to five to nine new transcripts from an 80 kb P1 clone that spans ten breakpoints. These transcripts, with one exception, appear to be expressed only at low levels in the set of cancer cell lines examined. Four transcripts are located between the previously mapped Ribophorin I gene and the most centromeric breakpoint; three map directly within the 20 kb spanning nine independent breakpoints. These data (i) show that among characterized leukemia breakpoint regions 3q21 is unusually gene rich, (ii) provide new candidates for relevance to leukemia in 3q21, and (iii) suggest possibilities for chromatin configuration effects.

Cytogenetics of chronic myelogenous leukaemia

The Philadelphia (Ph) chromosome is present in the leukaemic cells of most patients with chronic myelogenous leukaemia. Variant translocations occur in 10% of patients but breakpoints on chromosomes 9 and 22 remain the same, so prognosis of these patients is unchanged. Clonal evolution is infrequent in chronic phase and its significance depends on the specific chromosome involved, the number of metaphases affected and the timing in the chronic phase. The majority of patients in blastic phase demonstrate clonal evolution; three specific abnormalities (+Ph, +8 and isochromosome 17q) are present in 70% of patients. Loss of the Ph chromosome on therapy is associated with prolonged survival. For monitoring these events conventional G-band cytogenetics (CG) is essential at presentation to characterize the Disease cytogenetically, while fluorescence in situ hybridization (FISH) on hypermetaphase preparations (hypermetaphase FISH (HMF)) is important for establishing the specific frequency of Ph+ cells. During treatment FISH on interphase cells (I-FISH) can monitor the level of Ph+ cells in circulation, while CG may be used to identify any suspected clonal evolution. Where I-FISH is negative, HMF is essential to evaluate minimal residual disease.

Granulocytes with segmented nucleus retain normal chromosomes 17 in Philadelphia chromosome-positive chronic myeloid leukemia with i(17q) and pseudo-Pelger anomaly. A case report studied with fluorescence in situ hybridization

Previous reports suggested a correlation between the deletion of the terminal region of the short arm of a chromosome 17 and the appearance of dysgranulopoiesis in myeloproliferative disorders. Using the dual-color fluorescence in situ hybridization technique we analyzed the bone marrow and peripheral blood cells of a Philadelphia chromosome-positive chronic myeloid leukemia (CML) patient showing at the onset of transformation into blastic crisis both metaphases with the i(17q) as well as granulocytes without nuclear segmentation. This phenomenon is defined as pseudo-Pelger-Huët anomaly. Using two probes, one specific for 17p and one for 17q, we determined the presence or absence of the i(17q) in both metaphase and interphase cells. Moreover, we observed that all cells with a polysegmented nucleus typical of mature granulocytes did not have i(17q) but had two normal chromosomes 17. This observation confirmed the correlation between 17p deletion and the appearance of pseudo-Pelger anomaly. This finding may also be useful from a clinical point of view: the appearance of pseudo-Pelger cells in CML indicates that 17p deletion actually occurred. This event implies a negative prognosis.

FLANG (fludarabine + cytosine arabinoside + novantrone + G-CSF) induces partial remission in lymphoid blast transformation of Ph+chronic myelogenous leukaemia

The adenine nucleoside analogue, fludarabine phosphate, in combination with cytosine-arabinoside (Ara-C) and granulocyte-colony stimulating factor (G-CSF) (the so called FLAG regimen) has recently been shown to be effective in the treatment of poor-prognosis acute non-lymphoid leukaemia. We used this combination plus novantrone (FLANG regimen) in a case of Ph1+ chronic myeloid leukaemia (CML) unresponsive to interferon alpha that had progressed to an acute phase, after 3 months of treatment with 6-mercaptopurine and hydroxyurea. The patient was treated with two courses of fludarabine 30 mg/m2 (days 1-5) + Ara-C 2 g/m2 (days 1-5) + novantrone 5 mg/m2 (days 1-3) and G-CSF from day 0 to neutrophil recovery. After the first cycle of chemotherapy, bone marrow blasts decreased from 100% to less than 5% (clinical complete remission), with a progressive clearance of Ph1+ metaphases (from 100% to 12%). At the end of the second course, a progressive increase of blasts was observed again and karyotypic detection of Ph+ cells was also documented (from 12% to 42.9%). During this partial remission, the patient underwent an allogeneic bone marrow transplantation from an HLA matched identical brother. At the time of this report, he is still alive and well and in complete karyotypic remission. This partial therapeutic success was compared with the result obtained in another previously reported CML case: differences in the therapeutic efficacy of protocols employing fludarabine nucleosides and the type of blastic cells involved are discussed.

Leukemia treatment in severe combined immunodeficiency mice by antisense oligodeoxynucleotides targeting cooperating oncogenes

Transformation of hematopoietic cells by the p210bcr/abl tyrosine kinase appears to require the expression of a functional MYC protein, suggesting that simultaneous targeting of BCR-ABL and c-myc might be a rational strategy for attempting treatment of Phil-adelphia leukemia. To test this hypothesis, severe combined immunodeficiency mice injected with Philadelphia leukemic cells were treated systemically with equal doses of bcr-abl or c-myc antisense oligodeoxynucleotides (ODNs) or with both ODNs in combination. Compared with the mice treated with individual agents, the disease process was much slower in the group treated with both ODNs, as revealed by flow cytometry, clonogenic assay, and reverse transcriptase-polymerase chain reaction analysis to detect leukemic cells in mouse tissue cell suspensions, and by enumeration of liver metastases. The retardation of the disease process was positively correlated with a markedly increased survival of leukemic mice treated with both ODNs. These data demonstrate the therapeutic potential of targeting multiple cooperating oncogenes.

Chromosome 17 abnormalities and inactivation of the p53 gene in chronic myeloid leukemia and their prognostic significance

We have reviewed all the relevant studies on the loss of the short arm of chromosome 17 (17p) and inactivation of the p53 gene in chronic myelogenous leukemia (CML) in an attempt to clarify their roles in the progression of CML. Loss of a 17p (hemizygous 17p) and p53 inactivation emerged as the disease progressed and were closely associated with each other. About half of the cases with loss of a 17p, however, did not show p53 inactivation. In these cases loss of a 17p preceded p53 inactivation, which suggested that either reduction of the p53 gene dosage or inactivation of another tumor-suppressor gene on 17p might contribute to the disease progression. Both loss of a 17p and p53 inactivation may serve as poor prognostic factors but the prognostic significance of the former only emerged when metaphase cells with loss of a 17p were dominant amongst the total cell population analyzed.

Growth inhibition of leukaemic cells carrying the t(3;21) by the AML1/EVI-1-specific antisense oligonucleotide

The t(3;21)(q26;q22) translocation is thought to play an important role in the acute phase transformation of CML. The formation of the AML1/EVI-1 fusion gene by the translocation leads to expression of the AML1/EVI-1 fusion protein. Here we demonstrate that the AML1/EVI-1-specific antisense oligonucleotide markedly decreases the [3H]thymidine incorporation and growth of leukaemic cells carrying the t(3;21) and the t(9;22), but not those of K562 cells. These results indicate that the AML1/EVI-1 fusion protein could contribute to proliferation of the t(3;21)-carrying leukaemic cells after entering the blastic crisis phase of CML.

Cytogenetics of twelve cases of uveal melanoma and patterns of nonrandom anomalies and isochromosome formation

We present cytogenetic data of 12 new cases of uveal melanoma. One case showed a hypotetraploid chromosome number; the others were near-diploid. Underrepresentation or monosomy of chromosome 3 as well as multiplication of chromosomes 8, 8q, or regions of 8q was found in five cases. Both anomalies were observed in three cases. In two of these, multiplication of 8q resulted from isochromosome formation. The smallest multiplicated region seemed to be 8q23-24-->qter. Chromosome 6 anomalies were found in five cases without monosomy 3. Aberrations of chromosome 21 were seen in five cases and found to be the only cytogenetic change in two of them. These anomalies may define a subgroup of uveal melanoma. An anomaly of chromosome 1 was found in three cases. Anomalies of other chromosomes were detected in at most two cases each. Nonclonal centromeric or telomeric associations were seen in one case and different nonclonal ring chromosomes in another. Underrepresentation of chromosome 3 was seen exclusively in tumors with ciliary body involvement, while anomalies of chromosome 6 were detected only in pure choroideal melanomas. A review of the published cytogenetic data of untreated uveal melanoma supports our finding that monosomy 3 is frequently associated with multiplication of 8q but rarely with anomalies of chromosome 6, whereas the opposite is true for tumors with disomy 3, and that isochromosomes are closely associated with monosomy 3. Thus, cells with monosomy 3 seem to predispose to isochromosome formation.

Association of 17p loss with late-stage or refractory disease in hematologic malignancy

Twenty-five patients with loss of part or all of 17p were selected from 701 patients with hematologic malignancies karyotyped either at diagnosis and/or at relapse and/or in refractory disease. Loss of 17p resulted from partial arm deletion (eight cases), unbalanced translocation (12 cases), i(17)(q10)(five cases) or monosomy 17 (four cases). In three cases, both 17ps were missing; in one case, two sublines independently acquired loss of 17p. In eight cases, loss of 17p was confirmed as a secondary change. The karyotypes generally were complex, with an average of 4.0 structurally abnormal chromosomes in the simplest lines showing 17p loss. The incidence at diagnosis was acute lymphoblastic leukemia (ALL) 2.2%, acute myeloid leukemia (AML) 2.4%, and myelodysplastic syndrome (MDS) 3.4%. The incidence in relapse and refractory disease was ALL 8.9%, AML 3.3%, and MDS 6.3%. The increased incidence of 17p loss in relapse and refractory disease was statistically significant (p < 0.05). Loss of 17p appears to be a feature of late-stage or resistant disease in hematologic malignancy.

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.

Trisomy 8 detection in Ph+ CML patients using conventional cytogenetic and interphase fluorescence in situ hybridization techniques

We examined bone marrow (BM) cells from 6 Philadelphia chromosome positive (Ph+) chronic myeloid leukemia (CML) patients in advanced phase of the disease using conventional cytogenetic techniques and fluorescence in situ hybridization (FISH) for detection of an extra chromosome 8. All patients showed mosaicism for trisomy 8 as a secondary chromosome abnormality. For FISH, we used the D8Z5 probe specific for the centromeric region of chromosome 8 and analyzed 300 interphase nuclei and a variable number of mitoses for each patient. The percentages of metaphases carrying trisomy 8 were similar with both techniques, whereas the percentage of interphase nuclei showing three hybridization spots indicative of trisomy 8 was significantly lower than that in metaphases. This finding suggests that cells with a supernumerary chromosome 8 may have a cell cycle time shorter than that of disomic cells.

Comparison of clinical and biologic features between myeloid and lymphoid transformation of Philadelphia chromosome positive chronic myeloid leukemia

Analysis of clinical and biologic features of chronic myeloid leukemia (CML) in blast crisis (BC) was performed on 36 patients: 25 had myeloid and 11 had lymphoid transformation. The median duration from diagnosis to onset of BC was significantly shorter in patients with lymphoid BC (6 months) than in those with myeloid BC (41 months). Patients in lymphoid transformation showed better response to therapy and had a significantly longer median survival time after BC than patients with myeloid transformation (56% vs 0% and 10 months vs 4 months, respectively). The leukemic cells from all the patients with lymphoid BC showed B-cell immunophenotype, confirmed by the presence of immunoglobulin (Ig) heavy chain gene rearrangements in the five patients studied. Two of the eight patients with complete marker study expressed myeloid-associated antigens on the blasts. A high incidence of CD7 expression (7/17 or 41%) was found in patients with myeloid BC, but none of the patients who had DNA analysis showed rearrangement of T-cell receptor beta chain gene. Chromosomal abnormalities +8, +19, +21, and i(17q) were detected only in the patients with myeloid BC but not in those with lymphoid BC. Combined analysis of the patients in this series and those reported previously has revealed a statistically significant difference in the distribution of bcr breakpoints between myeloid and lymphoid BC: the bcr breakpoints in more than half of the patients with myeloid crisis were mapped to Zone 2 while those in patients with lymphoid crisis occurred most frequently in Zone 3.

Analysis of the p53 gene in patients with isochromosome 17q and Ph1-positive or -negative myeloid leukemia

Increased incidence of p53 gene aberrations or chromosome 17p monosomy resulting from an isochromosome 17q [i(17q)] has been observed with transition of chronic myelogenous leukemia (CML) to myeloid blast crisis (BC), and in some patients with poor risk acute myeloid leukemia (AML) progressing from myelodysplastic syndrome (MDS). These data suggested that disease progression may be linked to bi-allelic inactivation of p53. Here, we report on p53 gene analyses of nine patients with CML-BC and AML who showed an i(17q) as characteristic cytogenetic anomaly. Using Southern blots, agarose gel electrophoresis and single-strand conformation polymorphism analyses of PCR products from genomic DNA and cDNA, spanning exons 4 through 9, we did not detect any structural abnormalities of the remaining p53 allele. These findings question the hypothesis that p53 gene alterations are the principal molecular event responsible for progression of CML chronic phase or MDS to i(17q)-positive CML-BC or AML, respectively.

Double t(1;7)(p36;p11) in a megakaryocytic crisis of chronic myelogenous leukemia with variant t(5;9;22)

A 56-year-old man with chronic myelogenous leukemia (CML) who presented with a variant Ph chromosome, t(5;9;22)(q13;q34;q11), developed a unique additional chromosomal change of a double reciprocal t(1;7)(p36;p11) during the accelerated phase. A minor clone that had two copies of 1p+ and a copy of 7p- with a normal chromosome 7 was observed simultaneously. The patient underwent a megakaryocytic crisis. Surface marker of the blasts was positive for CD13, CD33, HLA-DR, CD41a, and CD42b, and negative for CD14 and lymphoid markers. Sequential chromosome analysis suggests that the double t(1;7) was caused by a multistep event consisting of duplication of both derivative chromosomes accompanied by loss of normal chromosomes 1 and 7. This may be the first report of a double reciprocal chromosomal translocation in a hematopoietic neoplasm.

The cytogenetic scenario of chronic myeloid leukemia

The Philadelphia chromosome (Ph), i.e., the reciprocal translocation t(9;22)(q34;q11), is found with great specificity in bone marrow cells from patients with chronic myeloid leukemia (CML). Variant Ph-producing translocations, seen in 5-10% of all patients, are all complex and involve the same molecular rearrangement as the regular t(9;22). Patients with classic and variant Ph-producing translocations are clinically and hematologically identical, and as a group differ from Ph-negative CML patients. In all patient groups, the occurrence of additional chromosome changes is an ominous sign indicating that disease progression is imminent. The chromosome changes occurring in excess of the Ph in CML are clearly nonrandom and two pathways of cytogenetic evolution may be distinguished. Major route changes comprise trisomy 8, i(17q), trisomy 19, and an extra Ph; totally, 71% of Ph-positive CML patients have at least one of these four major route changes. Six minor route changes, including five numerical abnormalities (-7, -17, +17, +21, and -Y) but also one structural aberration, t(3;21) (q26;q22), have been identified. At least one of these changes is found in 15% of all Ph-positive CML cases. Altogether, the four major route aberrations and the six minor route changes are present as part of the clonal evolution in 86% of CML with cytogenetic abnormalities in addition to the Ph chromosome.

Disappearance of a highly unusual clone, 46,XY,del(7)(p12),t(9;22)(q34;q11) in chronic myeloid leukemia after treatment with recombinant interferon and cytosine arabinoside

A patient with the typical features of the stable phase of chronic myeloid leukemia (CML) displayed two karyotypically related subclones. In addition to the t(9;22), cells from one clone contained a deletion of the short arm of chromosome 7, del(7)(p12), [46,XY,del(7)(p12),t(9;22)(q34;q11)]; the other contained only the standard translocation [46,XY,t(9;22)(q34;q11)]. Cells with a deletion of the short arm of chromosome 7 at band p12 as the only additional abnormality have not been observed previously in CML. Conventional chemotherapy with hydroxyurea and then with recombinant interferon-alpha (rIFN-alpha) did not reduce the population of either subclone. However, after treatment with a combination of rIFN-alpha and low-dose cytosine arabinoside (LoDac) continuously infused subcutaneously (s.c.), cells from the clone with the deleted chromosome 7 disappeared and normal metaphases were demonstrable.

Deletion (7)(p11p15) in a patient with Philadelphia-positive chronic myelogenous leukemia

We report a case of chronic myelogenous leukemia (CML) with a Philadelphia (Ph) chromosome. During the transformation phase of the disease, a del(7)(p11p15) and a +Ph were identified as additional chromosomal anomalies. We believe that loss of the segment 7p11-->p15 may play an important role in the progression of the disease.

t(9;11)(p22;q23) translocation in blastic phase of chronic myeloid leukemia

A patient with chronic myeloid leukemia showed clonal karyotypic evolution, with the appearance of an i(17q) and t(9;11)(p22;q23). This case sheds light upon leukemogenic events related to t(9;11)(p22;q23). The presence of t(9;22) and t(9;11) in the same clone showed that t(9;11) may affect a pluripotent stem cell, thus accounting for t(9;11) in both lymphoid and monocytic leukemias. In this patient, t(9;11) could not be related to a prior cytotoxic exposure and was instead the result of natural evolution of chronic myeloid leukemia. Furthermore, this led us to assume that the phenotype of blast cells may be determined by a chromosome abnormality. A phenotypic conversion from myeloblastic to undifferentiated morphologic aspect was observed when t(9;11) was detected, suggesting that t(9;11) may have induced a loss in differentiation of blast cells affected by this change. This assumption is in agreement with the putative presence of genes activated in pluripotent progenitors by 11q23 rearrangements.

Inversion of chromosome 16 and bone marrow eosinophilia in a myelomonocytic transformation of chronic myeloid leukemia

We report a case of chronic myeloid leukemia (CML) in myelomonocytic transformation associated with bone marrow (BM) eosinophilia. At diagnosis, all BM cells showed a Ph chromosome. At the time of blastic phase, more than 50% of Ph+ cells had a pericentric inversion of chromosome 16, inv(16)(p13q22). This case confirms that blastic transformation of CML can involve any committed progenitor, and myelomonocytic leukemia with BM eosinophilia is specifically associated with rearrangement of chromosome 16 at band p13 and q22.

Karyotype at relapse following allogeneic bone marrow transplantation for chronic myelogenous leukemia

Eighty-four patients underwent allogeneic or syngeneic bone marrow transplantation as therapy for chronic myelogenous leukemia (CML) during a 5-year period at The Johns Hopkins Oncology Center. We describe the karyotype at relapse in 19 patients who were Ph chromosome positive (Ph+) at diagnosis. Eighty-four percent of patients demonstrated clonal and/or nonclonal chromosome abnormalities in addition to the t(9;22)(q34;q11) at first detection of relapse or later during relapse. These abnormalities included: Ph plus additional clonal abnormalities (three patients), Ph plus nonclonal abnormalities (five patients), Ph plus additional clonal and nonclonal abnormalities (eight patients). Three patients had only the original Ph+ clone. The additional chromosome abnormalities were primarily structural, and entirely different from those most frequently observed during karyotypic evolution in conventionally treated CML. Chromosome 1 was most frequently involved, with 1q32 being the location of three clonal and two nonclonal abnormalities. Other sites included 6p21-22 (the site of two clonal abnormalities), 7p21-22, and 10q21 (the site of two clonal and one nonclonal abnormality each). Chromosomes 5 and 7q, regions of frequent involvement in acute nonlymphocytic leukemia that follows chemotherapy for other malignancies, were infrequently involved. The clinical significance of these additional abnormalities remains undetermined at this time.

Expression of the ETS2 and transferrin receptor genes in Philadelphia-positive chronic myeloid leukemia patients with a reciprocal t(3;21)

The translocation t(3;21)(q26;q22) is a rare recurring clonal abnormality, either preceding or associated with blast crisis in Philadelphia chromosome-positive chronic myeloid leukemia (CML) patients. We previously localized the chromosomal breakpoints at 3q26.2 and 21q22.2, using high resolution chromosomal analysis. Two genes of interest are localized near the breakpoints, the transferrin receptor gene and the ETS2 proto-oncogene. Their chromosomal localizations, determined by in situ hybridization on normal metaphase cells, were 3q29 and 21q22.3, respectively. They underwent a reciprocal translocation in patients with t(3;21). Their structures were not altered by the translocation, and both were expressed to varying levels in t(3;21) patients. Southern blotting investigations showed that the structure of other single-copy genes, including FIM3, localized near the breakpoints, were not affected by the translocation. An analysis of ETS2 expression performed on CML patients without t(3;21) showed the presence of the transcript in 100% of the blast crises, but only in 20% of the chronic-phase patients. Thus ETS2 expression may either be linked to or play a role in CML progression.

Chromosome studies of solid tumours

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