Ph-negative Chronic Myelogenous Leukemia Research Articles

Results of decitabine (5-aza-2'deoxycytidine) therapy in 130 patients with chronic myelogenous leukemia.

General and site-specific DNA methylation is associated with tumor progression and resistance in several cancers, including chronic myelogenous leukemia (CML). Decitabine is a hypomethylating agent that has shown encouraging preliminary anti-CML activity. This study evaluated the activity and toxicity of decitabine in different phases of CML. One hundred and thirty patients with CML were treated: 123 with Philadelphia chromosome (Ph)-positive CML (64 blastic, 51 accelerated, 8 chronic) and 7 with Ph-negative CML. Decitabine was given at 100 mg/m(2) over 6 hours every 12 hours x 5 days (1000 mg/m(2) per course) in the first 13 patients, 75 mg/m(2) in the subsequent 33 patients, and 50 mg/m(2) in the remaining 84 patients. A total of 552 courses were given to the 130 patients. Only four patients (3%) died during the first course from myelosuppressive complications (three patients) or progressive disease (one patient). Of 64 patients in the CML blastic phase, 18 patients (28%) achieved objective responses. Of these 18 patients, 6 achieved complete hematologic responses (CHR), 2 achieved partial hematologic responses (PHR), 7 achieved hematologic improvements (HI), and 3 returned to the second chronic phase (second CP). Five patients (8%) had cytogenetic responses. Among 51 patients in the accelerated phase, 28 patients (55%) achieved objective responses (12 CHR, 10 PHR, 3 HI, and 3 second CP). Seven patients (14%) had cytogenetic responses. Among eight patients treated in the chronic phase, five (63%) had objective responses. Of seven patients treated for Ph-negative CML, four (57%) had objective responses. There was no evidence of a dose-response effect. The estimated 3-year survival rate was less than 5% in the blastic phase and 27% in the accelerated phase. The only significant toxicity reported was severe myelosuppression, which was delayed, prolonged, and dose dependent. With decitabine 50-75 mg/m(2), the median time to granulocyte recovery above 0.5 x 10(9)/L was about 4 weeks. Myelosuppression-associated complications included febrile episodes in 37% and documented infections in 34%. Decitabine appears to have significant anti-CML activity. Future studies should evaluate lower-dose, longer-exposure decitabine schedules alone in imatinib-resistant CML, as well as combinations of decitabine and imatinib in different CML phases.

Characteristics and outcome of patients with Philadelphia chromosome negative, bcr/abl negative chronic myelogenous leukemia.

Up to 5% of patients with chronic myelogenous leukemia (CML) do not have the Philadelphia (Ph) translocation t(9;22)(q34;q11) or a bcr/abl molecular rearrangement. Although the diagnostic criteria of this entity are still under debate, there is general agreement that patients with Ph negative, bcr/abl negative CML have a severe clinical course that is not affected significantly by current treatment options. A population of 76 patients with bcr/abl negative CML who had received minimal or no previous therapy was characterized carefully with the intent of investigating clinical and hematologic variables and their association with survival by univariate, correlation, and multivariate analyses. A group of 73 patients with Ph negative CML who were not tested for the bcr/abl rearrangement (bcr/abl unknown) was analyzed separately and used for extension of the analysis. In the bcr/abl negative patient population, the median overall survival was 24 months. At the time of the analysis, 38 patients (50%) had died, and blastic transformation preceded death in 31%. Chromosomal abnormalities were found in 30% of the 76 patients, with trisomy 8 the most common abnormality. Complex chromosomal abnormalities were rare, and monosomy 7 was not observed. Survival was not affected significantly by treatment. Multivariate analysis identified older age (> 65 years), anemia (hemoglobin < 10 g/dL), and severe leukocytosis (white blood cells > 50 x 10(9)/L) as variables with independent prognostic significance for poor survival. A prognostic scoring system stratified patients into a low-risk group (53%) and a high-risk group (47%), with median survivals of 38 months and 9 months, respectively. Bcr/abl negative CML is a distinct clinical entity associated with very poor prognosis. Two risk categories are identifiable using a simple scoring system based on age, hemoglobin level, and leukocyte number.

Clinical significance of reverse BCR/ABL gene rearrangement in Ph-negative chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) is a clonal myeloproliferative disorder resulting from a neoplastic transformation of primitive hematopoietic stem cells of the bone marrow [1]. CML is a multistage disease and is generally asymptomatic in the beginning but progresses through an accelerated phase to blast crisis within 3–5 years and is ultimately fatal [2]. Based on clinical and morphological features, CML, has evolved into a distinct clinical entity from other types of leukemias and myeloproliferative disorders [3]. The genetic basis responsible for the transformation to CML is poorly understood. The presence of the Ph-chromosome in a hyper-cellular bone marrow without increased blasts [5,6] has been associated with the disease [4]. During the past 150 years, this disease has fascinated many. The landmark discovery of the Ph-chromosome in 1960 and its involvement with the long arms of chromosomes 9 and 22 resulting in a balanced translocation [t(9:22)] has provided a novel tool for investigating the chromosomal basis of other hematological malignancies [7]. A decade later the Ph-chromosome was found in a number of non-CML malignancies; this finding intrigued us all. Consequently, this aberration became the subject of molecular scrutiny and debate [8]. During t(9;22) translocation, the most distal band (q34) on chromosome 9, containing the c-abl protooncogene, is translocated onto the 5.8 kb major breakpoint cluster region (M-bcr) on chromosome 22 band q11.2, forming a fusion BCR/ABL gene [9]. The breakpoint on chromosome 9 occurs in a large region of about 200 kb between exon 1b and exon 2 of the c-abl proto-oncogene. The BCR gene on chromosome 22 is 70 kb in length and the breakpoints within the M-bcr generally occur such that either exon b2 or exons b2 and b3 are included in the fusion gene. The two different breakpoints are referred to as b2-a2 and b3-a2 [10]. The frequency of b2-a2 and b3-a2 fusions is equally common in CML, [11]. Nevertheless, a novel 8.5 kb mRNA is transcribed from these two genes producing an aberrant fusion protein of 210 kD [p210] that is phosphorylated on tyrosine and has increased tyrosine kinase activity compared to the normal c-ABL. The BCR-ABL gene has a fundamental role in the pathogenesis of CML [12]. Certain breakpoints within the BCR gene appear to correlate with specific leukemias. The p, p and p fusion proteins are associated with acute lymphoblastic leukemia, CML, and chronic neutrophilic leukemia (CNL), respectively. A classification based on molecular markers may lead to an improved diagnosis of disease for a better therapeutic intervention [13–28]. About 5% of CML patients in whom the Ph-chromosome is not discernible by routine banding techniques are termed Ph-negative [29]. In one-third of such patients, the BCR/ABL gene rearrangement now can be detected by a number of molecular techniques [30–33]. Abbre6iations: CML, chronic myelogenous leukemia; FISH, fluorescence in situ hybridization; M-bcr, major breakpoint cluster region; PCR, polymerase chain reaction.. * Corresponding author. Tel.: +1-718-9636100; fax: +1-7189636759.

The Abl/bcr Fusion Gene on Chromosome 9 in Ph-Negative Chronic Myelogenous Leukemia : A Case for Vigilance in Fluorescence In Situ Hybridization Interpretation

We report cytogenetic, fluorescence in situ hybridization (FISH), and molecular analysis in a case of Ph-negative chronic myelogenous leukemia patient with ABL/BCR fusion gene on chromosome 9 and a disparate FISH signal pattern using two commercially available bcr/abl probes (Vysis, Inc. and Oncor, Inc.). Cytogenetic analysis revealed a 46,XX normal female karyotype. FISH studies using Vysis LSI bcr/abl probe in interphase cells demonstrated a BCR/ABL fusion pattern, similar to that of m- BCR/ABL fusion found in acute lymphoblastic leukemia. However, examination of metaphases revealed the ABL/BCR fusion signal on one of the chromosomes 9, an ABL signal on the other chromosome 9, and two BCR signals of different sizes on each of the chromosomes 22. Subsequently, a FISH study with the Oncor major (M)- bcr/abl translocation probe confirmed the ABL/BCR fusion signal on chromosome 9 in addition to an ABL signal and a BCR signal located on chromosomes 9 and 22, respectively. Molecular studies (RT-PCR) revealed a rearrangement of the M- BCR region and expression of a chimeric bcr/abl mRNA of b3a2 configuration. This case suggests that it is imperative to have a full understanding of both the capabilities and the limitations of bcr/abl translocation probes and that FISH interphase signals should be confirmed on metaphase spreads for accurate diagnosis.

A Philadelphia Negative Chronic Myelogenous Leukemia with the Chimeric BCR/ABL Gene on Chromosome 9 and a b3-a2 Splice Junction

Approximately 5% of patients with chronic myelogenous leukemia (CML) do not reveal the Philadelphia (Ph) chromosome cytogenetically and are termed Ph-negative CML cases. We report one such case, which appeared normal by routine banding techniques. The BCR/ABL rearrangement was detected by reverse transcriptase–polymerase chain reaction and Southern blotting analysis, which suggested a b3-a2 splice junction. Dual color fluorescence in situ hybridization (FISH) with BCR and ABL DNA probes showed that the chimeric fusion gene was localized on chromosome 9q34, rather than at the typical location on chromosome 22q11. The BCR/ABL rearrangement was detected in 75% of the patient’s bone-marrow population, whereas the remaining 25% of the cells appeared normal. The use of dual color FISH in the diagnosis of CML is extremely valuable not only in identifying cases of Ph-negative CML, but also in quantifying the proportion of transformed cell populations. This information ultimately results in an enhancement of our ability to monitor therapy, follow disease progression, and determine transplant eligibility.

Philadelphia chromosome-negative chronic myelogenous leukemia with rearrangement of the breakpoint cluster region. Long term follow-up results

Five to 10% of patients with chronic myelogenous leukemia (CML) do not have the Philadelphia chromosome (Ph), but one-third of them have rearrangements of the breakpoint cluster region (BCR-positive). The authors analyzed the characteristics, treatment response, and prognosis of 23 patients with BCR-positive, Ph-negative CML, and compared them with patients with Ph-positive CML, Ph-negative BCR-negative CML and chronic myelomonocytic leukemia (CMML) treated during the same period. Seventeen patients had early chronic phase CML, 3 had late chronic phase, 2 had accelerated phase, and 1 had blastic phase. The median age was 44 years (range, 14-71 years), median platelet count was 402 x 10(9)/l, and median leukocyte count was 86 x 10(9)/l. Fourteen of the 17 patients with early chronic phase CML received alpha-interferon; 12 (86%) achieved complete hematologic remission. Median survival in chronic phase CML was 60 months (range, 3-90+ months). Patients with Ph-negative BCR-positive CML and those with Ph-positive CML had similar characteristics and outcome. Compared with patients with Ph-negative BCR-negative CML and CMML, patients with Ph-negative BCR-positive CML and Ph-positive CML were significantly younger, had a significantly higher incidence of leukocytosis, thrombocytosis, and peripheral and marrow basophilia, and a significantly lower incidence of anemia, thrombocytopenia, marrow blast percent, and peripheral and marrow monocytosis. The median survival was 60 months for Ph-negative BCR-positive CML, 73 months for Ph-positive CML, 25 months for Ph-negative BCR-negative CML, and 9 months for CMML (P < 0.001). When analyzed adjusting for their stage, patients classified with Ph-negative BCR-positive CML. Stage I disease had a significantly better survival than did patients with Ph-negative BCR-negative CML (P < 0.02). Patients with Ph-negative BCR-positive CML are similar to those with Ph-positive CML and should be treated with the same approaches.

BCR-ABL Protein Expression in Peripheral Blood Cells of Chronic Myelogenous Leukemia Patients Undergoing Therapy

Chronic myelogenous leukemia (CML) is a myeloproliferative disorder associated with the Philadelphia chromosome (Ph1) in more than 95% of these patients. The Ph1 and the resulting BCR-ABL fused genes are markers for this type of leukemia. In CML, the product of the fused BCR-ABL gene is typically a protein of approximately 2,000 amino acids termed P210 BCR-ABL. We have developed an assay for the BCR-ABL protein involving Western blotting of circulating white blood cells (WBC) with an anti-ABL monoclonal antibody that can detect P210 BCR-ABL and P145 ABL in peripheral blood cells from chronic phase Ph1-positive leukemia patients. This assay was used to analyze the BCR-ABL protein content of circulating WBC from CML patients before and after various treatments. In parallel to changes in percentages of Ph1-positive blood cells as determined by cytogenetic analyses of bone marrow samples, BCR-ABL protein expression in blood cells decreased or increased as patients entered remission or underwent relapse. Of interest, six Ph1-negative CML patients were BCR-ABL protein-positive. All except one had a rearrangement in the major breakpoint cluster region and that patient expressed P185 BCR-ABL and not P210. Our results indicate that the BCR-ABL Western blotting assay has clinical applications for both diagnosis and prospective evaluation of Ph1-positive and Ph1-negative CML patients.

BCR-ABL protein expression in peripheral blood cells of chronic myelogenous leukemia patients undergoing therapy

Chronic myelogenous leukemia (CML) is a myeloproliferative disorder associated with the Philadelphia chromosome (Ph1) in more than 95% of these patients. The Ph1 and the resulting BCR-ABL fused genes are markers for this type of leukemia. In CML, the product of the fused BCR- ABL gene is typically a protein of approximately 2,000 amino acids termed P210 BCR-ABL. We have developed an assay for the BCR-ABL protein involving Western blotting of circulating white blood cells (WBC) with an anti-ABL monoclonal antibody that can detect P210 BCR-ABL and P145 ABL in peripheral blood cells from chronic phase Ph1-positive leukemia patients. This assay was used to analyze the BCR-ABL protein content of circulating WBC from CML patients before and after various treatments. In parallel to changes in percentages of Ph1-positive blood cells as determined by cytogenetic analyses of bone marrow samples, BCR-ABL protein expression in blood cells decreased or increased as patients entered remission or underwent relapse. Of interest, six Ph1-negative CML patients were BCR-ABL protein-positive. All except one had a rearrangement in the major breakpoint cluster region and that patient expressed P185 BCR-ABL and not P210. Our results indicate that the BCR- ABL Western blotting assay has clinical applications for both diagnosis and prospective evaluation of Ph1-positive and Ph1-negative CML patients.

The application of fluorescent in situ hybridization to detect Mbcr/abl fusion in variant Ph chromosomes in CML and ALL

We investigated the usefulness of fluorescent in situ hybridization with different-colored major breakpoint cluster region (M bcr) and Abelson oncogene ( abl) probes in clinical practice. In standard Ph chromosomes with a M bcr breakpoint, these probes produced a fusion of M bcr and abl signals that was visible in interphase and metaphase cells. The normal range for apparent M bcr/abl fusion signals in interphase nuclei was established in bone marrow from 25 normal controls. We tested the probes on 35 bone marrow specimens from five normal subjects and 29 patients with various kinds of Ph chromosomes and chronic myelogenous leukemia or acute lymphocytic leukemia. This method produced M bcr/abl fusion signals in patients with a standard Ph chromosome, simple or complex variants of Ph chromosomes, and “Ph-negative chronic myelogenous leukemia.” In metaphase cells of patients with acute lymphocytic leukemia, this method established Ph chromosomes with minor bcr (m bcr) breakpoints. Fluorescent in situ hybridization is a relatively inexpensive and rapid method. When this method is used in conjunction with conventional chromosome analysis, the cytogeneticist can combine the power of complete karyotype studies and the resolution of molecular techniques for patients suspected of having a Ph chromosome.

Pure red cell aplasia in a case of Ph negative BCR/ABL rearranged CML with t(12;14)(q23;p11)

A patient with chronic myelogenous leukemia (CML) associated with pure red cell aplasia (PRCA) is reported. The occurrence of PRCA has been described previously in sporadic cases of Philadelphia chromosome (Ph) positive CML. In this patient, however, the Ph-chromosome was not detected; cytogenetic analysis revealed a t(12;14)(q23;p11) as the sole abnormality. Molecular studies by Southern and PCR analyses showed the rearrangement of the BCR and ABL sequences and expression of the chimeric bcr/abl mRNA, thus confirming the diagnosis of CML. To our knowledge, this is the first report on a case PRCA associated with Ph negative CML at diagnosis. The possible connection between CML and PRCA is discussed.

Essential thrombocythemia with the Philadelphia chromosome and BCR-ABL gene rearrangement: An entity distinct from chronic myeloid leukemia and Philadelphia chromosome-negative essential thrombocythemia

A 64-year-old woman presented with a platelet count of 3,225 × 10 9/L. Bone marrow morphology showed massive megakaryocytic hyperplasia; cytogenetic studies showed the presence of the Philadelphia chromosome (Ph). The presence of a rearrangement involving the major breakpoint cluster region (mbcr) on chromosome 22 was confirmed by Southern blotting techniques. A diagnosis of Ph positive essential thrombocythemia (ET) was made. Such cases constitute less than 5% of patients with ET and it has been proposed that they be considered examples of chronic myelogenous leukemia (CML) because of a shared propensity to progress to blast crisis. An argument is presented for retaining Ph positive ET as an entity separate from Ph negative ET and Ph positive CML.

Review of clinical, cytogenetic, and molecular aspects of Ph-negative CML

Between 1985 and 1989, many cases of Philadelphia (Ph) chromosome negative chronic myelogenous leukemia (CML) were reported. For this review, the following selection criteria were used: the original articles on Ph-negative cases should provide clinical, hematologic, cytogenetic as well as molecular data. In addition, eight unpublished cases of Ph-negative CML are included that were studied in our institute during the last two years. Our purpose was to correlate presence or absence of the Ph rearrangement with the clinical features in an attempt to test whether the entity “Ph-negative CML” really exists and to identify the pathologic characteristics, frequency of occurrence, prognosis for survival, and underlying molecular mechanisms. Data on Ph-negative CML patients were compared with data on Ph-positive CML, atypical CML (aCML), and chronic myelomonocytic leukemia (CMMoL), reported in the same papers as the Ph negative patients. Essential for comparison of data from the different investigators appeared to be a clear description of criteria they used to establish the diagnosis CML, or alternatively a complete presentation of data for all patients reported in the articles. In most cases. Ph-negative CML was distinguishable from CMMoL and aCML, using simple criteria, e.g., differential count of peripheral blood and absence of dysplasia in the bone marrow. Cytogenetic analysis showed normal karyotype in most cases of Ph-negative CML. Interestingly, in cases with abnormal karyotype, chromosome 9 band q34 was relatively frequently involved in translocations with other chromosomes than chromosome 22, suggesting a variant Ph translocation not visible by cytogenetic techniques. This assumption was confirmed by molecular analysis, demonstrating bcr-abl rearrangement in 9 out of 10 of the latter cases. Results of cytogenetic and molecular investigations in 136 cases of Ph-negative CML reviewed in this article clearly indicated that molecular techniques are valuable tools for identification of bcr-abl rearrangements, indicative for the Ph translocation. The different mechanisms responsible for bcr-abl rearrangement in Ph-negative CML patients are discussed. The question remains whether all Ph-negative CML patients will have bcr-abl rearrangements, or whether alternative mechanisms will be identified that are responsible for this disease.

Philadelphia Chromosome-Negative Chronic Myelogenous Leukemia Without Breakpoint Cluster Region Rearrangement: A Chronic Myeloid Leukemia with a Distinct Clinical Course

The hallmarks of chronic myelogenous leukemia (CML) include the Philadelphia chromosome (Ph) translocation [t (9;22)(q34;q11)] and consistent molecular genetic aberrations: a break within a restricted 5.8 kb DNA segment, bcr, on chromosome 22q11; transposition of the c-abl protooncogene from chromosome 9q34 to 22q11; and formation of a hybrid bar-abl gene encoding an abnormal 210 Kd bcr-abl protein with augmented tyrosine kinase enzymatic activity. These molecular phenomena may occur even in the absence of cytogenetic evidence of the Ph translocation. They are highly specific and sensitive markers for CML, and are presumed to play a significant role in the pathogenesis of this malignancy. Surprisingly, we have encountered 11 patients who lacked the Ph translocation, bcr rearrangement, and (in the four patients with available mRNA) a bcr-abl message, and yet had a disease phenotype at diagnosis that was a morphologic facsimile of classic chronic phase CML. These patients presented with high white blood cell counts, neutrophilia, occasional basophilia, splenomegaly, and a hypercellular bone marrow with granulocytic hyperplasia and a left shift in myeloid maturation. Despite the striking resemblance between the early stages of bcr-negative and bcr-positive CML, disease progression manifests distinctly in these two disorders. In contrast to the blastic transformation that inevitably complicates bcr-positive CML, the natural history of our 11 Ph-negative, bcr-negative CML patients was characterized by increasing leukemia burden with leukocytosis, pronounced organomegaly, extramedullary infiltrates, and eventual bone marrow failure (anemia and thrombocytopenia) without marked increases in blast cells. Our current observations suggest that a chronic myeloid leukemia process can develop without associated changes in the bcr or c-abl genes. Although the initial phase of this disease is indistinguishable from CML, the presence or absence of molecular markers may aid in the prediction of the clinical course of Ph-negative CML.

Philadelphia chromosome-negative chronic myelogenous leukemia without breakpoint cluster region rearrangement: a chronic myeloid leukemia with a distinct clinical course

The hallmarks of chronic myelogenous leukemia (CML) include the Philadelphia chromosome (Ph) translocation [t (9;22)(q34;q11)] and consistent molecular genetic aberrations: a break within a restricted 5.8 kb DNA segment, bcr, on chromosome 22q11; transposition of the c- abl protooncogene from chromosome 9q34 to 22q11; and formation of a hybrid bar-abl gene encoding an abnormal 210 Kd bcr-abl protein with augmented tyrosine kinase enzymatic activity. These molecular phenomena may occur even in the absence of cytogenetic evidence of the Ph translocation. They are highly specific and sensitive markers for CML, and are presumed to play a significant role in the pathogenesis of this malignancy. Surprisingly, we have encountered 11 patients who lacked the Ph translocation, bcr rearrangement, and (in the four patients with available mRNA) a bcr-abl message, and yet had a disease phenotype at diagnosis that was a morphologic facsimile of classic chronic phase CML. These patients presented with high white blood cell counts, neutrophilia, occasional basophilia, splenomegaly, and a hypercellular bone marrow with granulocytic hyperplasia and a left shift in myeloid maturation. Despite the striking resemblance between the early stages of bcr-negative and bcr-positive CML, disease progression manifests distinctly in these two disorders. In contrast to the blastic transformation that inevitably complicates bcr-positive CML, the natural history of our 11 Ph-negative, bcr-negative CML patients was characterized by increasing leukemia burden with leukocytosis, pronounced organomegaly, extramedullary infiltrates, and eventual bone marrow failure (anemia and thrombocytopenia) without marked increases in blast cells. Our current observations suggest that a chronic myeloid leukemia process can develop without associated changes in the bcr or c- abl genes. Although the initial phase of this disease is indistinguishable from CML, the presence or absence of molecular markers may aid in the prediction of the clinical course of Ph-negative CML.

Transformation of refractory anemia with excess of blasts into acute myelogenous leukemia with Ph‐negative chronic myelogenous leukemia‐like characteristics

We report a 56 year old patient with acute myelogenous leukemia (FAB classification: M2), in whom the number of mature myeloid cells similar to those seen in Ph-negative chronic myelogenous leukemia increased markedly 2 months after the diagnosis of refractory anemia with excess of blasts (RAEB). This is a rare case of leukemic evolution as a terminal event of RAEB.

Significance and correlations of molecular analysis results in patients with philadelphia chromosome-negative chronic myelogenous leukemia and chronic myelomonocytic leukemia

Several investigators have documented a rearrangement of the breakpoint cluster region (bcr) in selected patients with a morphologic diagnosis of chronic myelogenous leukemia (CML) but no abnormality of the Philadelphia chromosome (Ph) by cytogenetic studies. Our intention was to systematically investigate the incidence of the bcr rearrangement in such patients, and to correlate the findings with patient characteristics, response to therapy (especially alpha interferon treatment), and overall prognosis. Molecular analysis studies were performed in 40 patients with Ph-negative CML (23 patients) and myelomonocytic leukemia (CMML; 17 patients). Rearrangement of the breakpoint cluster region (bcr) was detected in 11 of the 23 patients with Ph-negative CML (48 percent), indicating the presence of the abnormal molecular events in Ph-positive CML without documentation of the Ph cytogenetic abnormality. None of the 17 patients with CMML had the bcr rearrangement. Patients with Ph-negative CML and the bcr rearrangement had characteristics similar to those of patients with Ph-positive disease. These included a younger age, higher white blood cell counts, a higher incidence of thrombocytosis and basophilia, and a lower occurrence of thrombocytopenia. The leukocyte alkaline phosphatase score was not a helpful distinguishing feature. Among 21 patients receiving alpha interferon-based regimens, response to therapy was significantly better among patients with Ph-negative disease and the bcr rearrangement (seven of seven, 100 percent), compared with those without the bcr rearrangement (one of six, 17 percent), or patients with CMML (two of eight, 25 percent) (p less than 0.01). At this time of follow-up, only one of the 11 patients with Ph-negative CML and the bcr rearrangement had died from complications of allogeneic bone marrow transplantation, compared with three deaths among the 12 patients with Ph-negative CML and no bcr rearrangement, and 11 deaths among the 19 patients with CMML. We conclude that molecular studies help in better understanding the nosology of Ph-negative CML, and define a subgroup of patients with clinical, therapeutic, and prognostic correlations similar to those of patients with Ph-positive CML.

Molecular and clinical investigations in Philadelphia chromosome-negative chronic myelogenous leukemia

We performed molecular studies in five cases of Philadelphia (Ph) translocation-negative chronic myelogenous leukemia (CML). Among the five, one case showed a 7q− anomaly; the remaining four had normal karyotypes. The 5′ or 3′ breakpoint cluster region ( bcr) DNA probes detected rearrangements in two of the five cases. The two cases with bcr rearrangement showed clinical and hematologic manifestations similar to those with Ph-positive CML; for example, basophilia in the peripheral blood and marked hepatosplenomegaly. On the other hand, the three Ph-negative CML cases without bcr rearrangement manifested somewhat different clinical manifestation; that is, they did not respond to busulfan therapy in the chronic phase. Our observations suggest a heterogeneity in Ph-negative CML with at least two subtypes: one with a rearranged bcr gene showing clinical and hematologic features akin to those of CML with a Ph translocation, and the other without such a rearrangement and with a somewhat different clinical feature. Furthermore, the present data point to the possibility of the existence of Ph-negative CML without bcr rearrangement.

Significance and correlations of molecular analysis results in patients with Philadelphia chromosome-negative chronic myelogenous leukemia and chronic myelomonocytic leukemia

<h3>Purpose</h3> Several investigators have documented a rearrangement of the breakpoint cluster region (<i>bcr</i>) in selected patients with a morphologic diagnosis of chronic myelogenous leukemia (CML) but no abnormality of the Philadelphia chromosome (Ph) by cytogenetic studies. Our intention was to systematically investigate the incidence of the <i>bcr</i> rearrangement in such patients, and to correlate the findings with patient characteristics, response to therapy (especially alpha interferon treatment), and overall prognosis. <h3>Patients and methods</h3> Molecular analysis studies were performed in 40 patients with Ph-negative CML (23 patients) and myelomonocytic leukemia (CMML; 17 patients). <h3>Results</h3> Rearrangement of the breakpoint cluster region (<i>bcr</i>) was detected in 11 of the 23 patients with Ph-negative CML (48 percent), indicating the presence of the abnormal molecular events in Ph-positive CML without documentation of the Ph cytogenetic abnormality. None of the 17 patients with CMML had the <i>bcr</i> rearrangement. Patients with Ph-negative CML and the <i>bcr</i> rearrangement had characteristics similar to those of patients with Ph-positive disease. These included a younger age, higher white blood cell counts, a higher incidence of thrombocytosis and basophilia, and a lower occurrence of thrombocytopenia. The leukocyte alkaline phosphatase score was not a helpful distinguishing feature. Among 21 patients receiving alpha interferon-based regimens, response to therapy was significantly better among patients with Ph-negative disease and the <i>bcr</i> rearrangement (seven of seven, 100 percent), compared with those without the <i>bcr</i> rearrangement (one of six, 17 percent), or patients with CMML (two of eight, 25 percent) (p < 0.01). At this time of follow-up, only one of the 11 patients with Ph-negative CML and the <i>bcr</i> rearrangement had died from complications of allogeneic bone marrow transplantation, compared with three deaths among the 12 patients with Ph-negative CML and no <i>bcr</i> rearrangement, and 11 deaths among the 19 patients with CMML. <h3>Conclusion</h3> We conclude that molecular studies help in better understanding the nosology of Ph-negative CML, and define a subgroup of patients with clinical, therapeutic, and prognostic correlations similar to those of patients with Ph-positive CML.

Mast cell disease followed by leukemia with clonal evolution

A 29-yr old woman developed urticaria pigmentosa which subsequently progressed through systemic mastocytosis to Philadelphia chromosome negative (Ph neg) chronic myelogenous leukemia (CML) with t(8;17). Further cytogenetic evolution occurred at the time of transformation to the aggressive phase of the disease. Unlike Ph-positive CML, chromosome number 9 was not involved, nor was the breakpoint cluster region located at band 22q11. This clearly separates this case from other Ph-negative CML patients who do have involvement of 9q34[1] or the breakpoint cluster region [2, 3]. Since this is the first case of its type to be reported with cytogenetic abnormalities, the clinical relevance of the unique chromosomal rearrangement t(8;17)(pll;q25) in the setting of systemic mastocytosis is unclear. Additional cases need to be reported to determine if this genetic rearrangement is a nonrandom marker of leukemia evolving in a setting of malignant mast cell disease.

Trisomy 11 in a patient with Ph-negative chronic myelogenous leukemia

A case of Ph-negative chronic myelogenous leukemia associated with functional reduction of platelets is described. Bone marrow cells examined in the blastic phase showed a stem line karyotype of 47, XY, +11.