Life after ponatinib failure: outcomes of chronic and accelerated phase CML patients who discontinued ponatinib in the salvage setting

Ponatinib is a pan-tyrosine kinase inhibitor (TKI) with efficacy in multirefractory CML patients who have failed other TKIs. Despite excellent response rates, resistance or intolerance may develop. We conducted a retrospective review of the outcome of patients with chronic (CP) and accelerated (AP) phase CML refractory to prior TKI who discontinued ponatinib for resistance or intolerance. Nineteen CP patients, discontinued due to resistance (n = 13), toxicity (n = 5) and to pursue stem cell transplantation (n = 1). At discontinuation, 14 were still in CP, three had progressed to AP and two to blast phase (BP). Three CP patients improved their cytogenetic response (CyR) to complete CyR (CCyR), two after SCT and one on omacetaxine. None of the 12 patients, without a major cytogenetic response at ponatinib discontinuation, including all patients treated with subsequent TKIs, responded to therapy. Seventeen AP patients, stopped ponatinib due to resistance (n = 15) or intolerance (n = 2). At discontinuation, 14 were still in AP and three had progressed to BP. Four patients were treated with SCT and one achieved major molecular response. None of the 12 patients treated with non-SCT approaches responded to subsequent therapy. Median survival for all patients was 16.6 months after ponatinib discontinuation (31, 9 and 13 months for patients in CP, AP and BP, respectively). Median survival was 60 months for patients who discontinued ponatinib for toxicity and 11 months for those who discontinued for resistance. Long-term outcome of patients with ponatinib failure are poor with estimated one-year OS and EFS rates of 54% and 40%, respectively. New treatment options are required for this subset of patients.

Hematopoietic stem cell transplantation for T315I-mutated chronic myelogenous leukemia

BACKGROUND

The T315I mutation of BCR/ABL gene is known to produce complete resistance of chronic myelogenous leukemia (CML) to all currently available BCR/ABL inhibitors. The data suggesting poor median survival of these patients may indicate that they should be primary candidates for allogeneic stem cell transplantation (alloSCT). However, evidence on efficiency of this treatment modality in CML with T315I mutation is lacking.

CASE REPORT

A 25-year-old patient was diagnosed with Philadelphia chromosome positive CML in accelerated phase. As he did not have an HLA-identical sibling or fully-matched unrelated bone marrow donor, treatment with low dose tyrosine kinase inhibitor - imatinib was initiated. Despite satisfactory hematological remission, he failed to achieve complete cytogenetic remission within the first year of treatment. Moreover, despite escalation of imatinib dosage, the disease relapsed after further 3 months of treatment. Molecular studies revealed T315I mutation of BCR/ABL gene. He responded poorly to interferon alpha (IFN-alpha) and we decided to perform alloSCT from a partially mismatched (8/10 HLA allele match) unrelated donor. The course of transplantation was complicated by staphylococcal sepsis, grade I skin acute GvHD and limited chronic skin GVHD. However, the goal of alloSCT was achieved and the patient remains in complete molecular remission at week +68 post-transplantation.

CONCLUSIONS

The clinical course of this case supports the idea that allogeneic hematopoietic transplantation is a viable treatment option for patients with CML bearing T315I mutation.

The growth factor independence-1 (Gfi1) is overexpressed in chronic myelogenous leukemia

The activation of ABL tyrosine kinase in BCR/ABL-positive chronic myelogenous leukemia (CML) leads to a diversity of biological changes related to the pathogenesis of the disease. In CML patients, we determined the expression of growth factor independence-1 (Gfi1), a transcription repressor with weak oncogenic activity. Our data demonstrated that the Gfi1 mRNA level in both the mononuclear cells and purified CD34(+) cells from CML were significantly higher as measured by quantitative real-time PCR. Using flow cytometry and Western blot, we also showed that the Gfi1 protein content was increased in CML CD34(+) cells. The expression of Gfi1 was correlated with BCR/ABL significantly. Gfi1 may be implicated in the pathogenesis of CML and can serve as a potential target for the management of the disease.

Overexpression ofCyclin D1in Accelerated-Phase Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is a bi- or triphasic disease. Molecular markers distinct for the phase evolution would be clinically helpful. For signaling transformation and proliferation activities in CML, Bcr-Abl is the pivotal protein. As downstream signals of Bcr-Abl , RAS, PI3-K, and Stat 5 may lead to cell cycle progression mediated by increased expression of cyclin Ds. We analyzed copy numbers of bcr-abl and cyclin D1 transcripts by reverse transcription (RT) and competitive PCR titration in bone marrow cells of 20 patients with CML, 10 in chronic phase (CP) and the other 10 in accelerated phase (AP). The level of bcr-abl transcripts in the AP was not significantly higher than that in the CP; in contrast, the level of cyclin D1 transcripts in the AP was significantly higher than that in the CP (p <0.001). Cyclin D1 RNA expression in the CP of CML was also found to have clinical relevance to time to AP transformation. The median time to AP transformation for the CP patients with cyclin D1 transcripts of 1.50 x 10(4)/microg RNA was significantly shorter than that for those with cyclin D1 transcripts < 1.50 x 10(4)/microg RNA (15 vs. 67 months, p=0.0354) although confirmation to conduct in a larger patient group is required. These results suggest that the expression level of cyclin D1 RNA in bone marrow cells is predictive of the phase evolution in CML and may be helpful in treatment decision-making.

Phase 3 study of dasatinib 140 mg once daily versus 70 mg twice daily in patients with chronic myeloid leukemia in accelerated phase resistant or intolerant to imatinib: 15-month median follow-up

Dasatinib is the most potent BCR-ABL inhibitor, with 325-fold higher potency than imatinib against unmutated BCR-ABL in vitro. Studies have demonstrated the benefits of dasatinib 70 mg twice daily in patients with accelerated-phase chronic myeloid leukemia intolerant or resistant to imatinib. A phase 3 study compared the efficacy and safety of dasatinib 140 mg once daily with the current twice-daily regimen. Here, results from the subgroup with accelerated-phase chronic myeloid leukemia (n = 317) with a median follow-up of 15 months (treatment duration, 0.03-31.15 months) are reported. Among patients randomized to once-daily (n = 158) or twice-daily (n = 159) treatment, rates of major hematologic and cytogenetic responses were comparable (major hematologic response, 66% vs 68%; major cytogenetic response, 39% vs 43%, respectively). Estimated progression-free survival rates at 24 months were 51% and 55%, whereas overall survival rates were 63% versus 72%. Once-daily treatment was associated with an improved safety profile. In particular, significantly fewer patients in the once-daily group experienced a pleural effusion (all grades, 20% vs 39% P < .001). These results demonstrate that dasatinib 140 mg once daily has similar efficacy to dasatinib 70 mg twice daily but with an improved safety profile. This trial is registered at www.clinicaltrials.gov as #CA180-035.

[Multiplex fluorescence in situ hybridization for detecting complex chromosomal aberrations in chronic myeloid leukemia in blast crisis]

OBJECTIVE

To investigate the value of multiplex fluorescence in situ hybridization (M-FISH) for the detection of complex chromosomal abnormalities (CCA) of chronic myeloid leukemia in blast crisis (CML-BC).

METHODS

M-FISH was used to study 26 cases of CML-BC with CCA assayed by conventional cytogenetics (CC).

RESULTS

Sixty-nine kinds of structural rearrangements were detected by M-FISH besides typical t (9;22) translocation, among them only 10 were balanced ones and 59 unbalanced ones including 1 insertion, 6 deletions, 52 translocations and derivative chromosomes. In addition, 23 numerical abnormalities were detected. All chromosomes were involved in CML-BC, and chromosomes 17, 2, 8, 16 involvements were the most frequent. M-FISH failed to find out the abnormal clone in 1 case, discovered CCA clones that were missed CC in 6 cases. Clarified 16 kinds of aberrations which could not be identified CC and corrected 5 aberrations made wrong description by CC. Thirty-five kinds of translocations were found by M-FISH which were missed by CC. The aberrations of der (9) t (16; 6; 9; 22) and der (18) t (16; 18; 19) we found were reported in the literature for the first time.

CONCLUSIONS

M-FISH can refine CCA in CML-BC, find out or correct the missed or misidentified abnormalities by CC. The frequent secondary chromosomal abnormalities in CML-BC with CCA are different from that in CML.

[Detection of FLT3 gene and FLT3/ITD gene mutation in chronic myeloid leukemia and its significance]

BACKGROUND & OBJECTIVE

Fms-like tyrosine kinase 3 (FLT3)gene abnormal expression could be detected in most of acute myeloid leukemia (AML)patients, and 20%-30% of them have FLT3/ITD gene mutation which indicate poor prognosis. This study was to detect FLT3 gene expression, and FLT3/ITD gene mutation in chronic myeloid leukemia (CML)patients, and analyze their relationships with prognosis.

METHODS

Polymerase chain reaction (PCR)was used to detect FLT3 gene expression, and FLT3/ITD gene mutation in 53 CML patients of chronic phase,and 34 CML patients of accelerated phase or blast crisis.

RESULTS

FLT3 gene was detected in 5.7%(3/53)CML patients of chronic phase, and in 55.9% (19/34)CML patients of accelerated phase or blast crisis,the difference of FLT3 gene positive rate between these 2 groups was significant (P< 0.001). Only 2 of 87 CML patients (2.3%)were found with FLT3/ITD mutation.

CONCLUSIONS

FTL3 gene expresses mainly in CML patients of accelerated phase or blast crisis. FTL3/ITD gene mutation was seldom involved in CML patients. The CML patients with FLT3 gene expression and FTL3/ITD gene mutation may have poor prognosis.

Determination of secondary chromosomal aberrations of chronic myelocytic leukemia

Chronic myeloctyic leukemia (CML) is a stem cell disorder characterized by the cytogenetic abnormality of t(9;22)(q34;q11.2), which progresses from a chronic phase to an accelerated phase (AP), and/or a blast phase (BP) of myelocytic or lymphoid phenotype. This progression is frequently preceded or accompanied by recurring secondary chromosomal abnormalities (SCA) that are believed to play a role in the transformation and may also serve as valuable prognostic indicators. Failure to note such abnormalities may lead to an inappropriate clinical evaluation. We observed CML patients with AP or BP who did not show SCA by routine cytogenetic analysis. To determine the presence or absence of specific SCA in those cases, we applied fluorescence in situ hybridization (FISH) to four CML cases with pseudodiploid cytogenetics [t(9;22)(q34;11.2) as the sole abnormality] by conventional karyotyping. Bone marrow biopsies from two AP and two BP of CML patients with pseudodiploid karyotypes by conventional cytogenetics were examined by FISH for trisomy 8 and i(17q). These SCA are major secondary chromosomal changes seen in BP of CML patients. Results were considered positive if more than 2.4% of cells had +8 and >6.25% for i(17q) by FISH. Four out of four patients were positive for +8. These results indicate that FISH techniques are valuable in the determination of SCA in CML, which were t(9;22)(q34;q11.2) positive as the sole cytogenetic abnormality with standard G-banding karyotyping and can be helpful for the early diagnosis of CML progression.

Differences in BCL-X(L) expression and STAT5 phosphorylation in chronic myeloid leukaemia patients

Chronic myelogenous leukaemia (CML) cells show expression of BCL-X(L), an anti-apoptotic oncogene. This expression is induced by BCR-ABL protein kinase through activation of the signal transducer and activator of transcription-5 protein (STAT5). To date, however, the contribution of BCL-X(L) and STAT5 to the transforming phenotype in CML is still unclear. This study was aimed at defining the status of activated STAT5 and BCL-X(L) expression and their relation to BCR-ABL rearrangement in CML cells derived from patients at different clinical stages. Twenty-seven consecutive patients with CML were enrolled in the study. Peripheral blood mononuclear cells were lysed and subjected to immunoprecipitation and Western blotting to analyse phosphorylated STAT5. The p210 BCR-ABL rearrangements were determined by reverse transcriptase-polymerase chain reaction (RT-PCR) and BCL-X(L) expression by semi-quantitative RT-PCR. We found that increased transcription of BCL-X(L) gene was associated with phosphorylated STAT5 in the majority of blast crisis patients and in a few accelerated and chronic phase patients. Moreover, BCL-X(L) expression levels were found to be decreased in chronic phase, contrary to a marked increase in blast crisis. We found no difference in expression of BCL-X(L) and phosphorylated STAT5 when related with b3a2 and b2a2 BCR-ABL rearrangements. These results suggest that STAT5 activity and BCL-X(L) overexpression may reflect a stage of differentiation among CML phases, and this could contribute to BCR-ABL-dependent transformation.

Frequent methylation of p16INK4A and p14ARF genes implicated in the evolution of chronic myeloid leukaemia from its chronic to accelerated phase

The frequency and mechanism of p16(INK4A) and p14(ARF) gene alterations were studied in cell samples from 30 patients with Philadelphia (Ph) chromosome-positive chronic myeloid leukaemia (CML), both at diagnosis and at the onset of the accelerated phase (AP) of the disease. No alterations in the p16(INK4A) or p14(ARF) genes were found in any of the chronic phase (CP) samples. DNA sequencing analyses detected p16(INK4A) or p14(ARF) mutations in 17 AP samples. All mutations were heterozygous without loss of the other allele. Aberrant methylation of the p16(INK4A) or p14(ARF) promoters was found in 14 of 30 AP samples. The most common situation was the simultaneous methylation of both promoters. Our data indicate that p16(INK4A) and p14(ARF) are primary targets for inactivation by promoter methylation in the acceleration of CML. Transcriptional silencing of the p16(INK4A) and p14(ARF) genes may be important in the conversion of CML from the CP to the AP.

The effect of dose increase of imatinib mesylate in patients with chronic or accelerated phase chronic myelogenous leukemia with inadequate hematologic or cytogenetic response to initial treatment

PURPOSE

Imatinib mesylate is a tyrosine kinase inhibitor with high affinity for the BCR-ABL fusion protein expressed by the hematopoietic cells in chronic myelogenous leukemia (CML). Some patients with chronic-phase or accelerated-phase CML either relapse after an initial response or are refractory to imatinib, prompting us to evaluate the efficacy of dose increase in such patients.

EXPERIMENTAL DESIGN

Twelve chronic-phase patients initially receiving 400 mg/day and 4 patients with accelerated phase initially receiving either 400 mg/day (two patients) or 600 mg/day (two patients) had their dose increased (14 to 800 mg/day and 2 to 600 mg/day) because of progressive disease (usually clonal evolution) or inadequate cytogenetic response after at least 1 year of therapy.

RESULTS

Six patients had major cytogenetic responses after dose increase (3 complete and 3 partial). Two others had minor cytogenetic responses. Two patients with clonal evolution transiently lost the additional clonal aberrations. Almost all of the responses occurred within 6 months, and were typically 3-6 months in duration. However, 3 patients have continuing major cytogenetic responses of >18 months duration. Dose increase was well tolerated, with thrombocytopenia, mild leukopenia, and exacerbation of prior edema being the most common adverse events.

CONCLUSIONS

Although increasing the dose of imatinib can benefit a subgroup of patients with CML with either an inadequate cytogenetic response or disease progression, our results suggest the majority will not have a sustained meaningful response, and that other options, such as allogeneic stem cell transplant or investigational therapies, also need to be considered at the time of dose increase.

The usefulness of monitoring WT1 gene transcripts for the prediction and management of relapse following allogeneic stem cell transplantation in acute type leukemia

In acute-type leukemia, no method for the prediction of relapse following allogeneic stem cell transplantation based on minimal residual disease (MRD) levels is established yet. In the present study, MRD in 72 cases of allogeneic transplantation for acute myeloid leukemia, acute lymphoid leukemia, and chronic myeloid leukemia (accelerated phase or blast crisis) was monitored frequently by quantitating the transcript of WT1 gene, a "panleukemic MRD marker," using reverse transcriptase-polymerase chain reaction. Based on the negativity of expression of chimeric genes, the background level of WT1 transcripts in bone marrow following allogeneic transplantation was significantly decreased compared with the level in healthy volunteers. The probability of relapse occurring within 40 days significantly increased step-by-step according to the increase in WT1 expression level (100% for 1.0 x 10(-2)-5.0 x 10(-2), 44.4% for 4.0 x 10(-3)-1.0 x 10(-2), 10.2% for 4.0 x 10(-4)-4.0 x 10(-3), and 0.8% for < 4.0 x 10(-4)) when WT1 level in K562 was defined as 1.0). WT1 levels in patients having relapse increased exponentially with a constant doubling time. The doubling time of the WT1 level in patients for whom the discontinuation of immunosuppressive agents or donor leukocyte infusion was effective was significantly longer than that for patients in whom it was not (P <.05). No patients with a short doubling time of WT1 transcripts (< 13 days) responded to these immunomodulation therapies. These findings strongly suggest that the WT1 assay is very useful for the prediction and management of relapse following allogeneic stem cell transplantation regardless of the presence of chimeric gene markers.

Blast crisis of chronic myeloid leukemia: diagnosis prompted by T(8;9)

T(8;9) is a relatively new translocation that has been reported in a few patients with chronic myeloid leukemia (CML) but never in acute myeloid leukemia (AML). We report here a patient who presented with AML with t(8; 9). He lacked the Philadelphia chromosome but tested positive for the gene by the polymerase chain reaction method. This confirmed the diagnosis of CML with blast crisis, and appropriate treatment could be instituted

Treatment of philadelphia chromosome-positive, accelerated-phase chronic myelogenous leukemia with imatinib mesylate

PURPOSE

Imatinib mesylate, a specific Bcr-Abl tyrosine kinase inhibitor, has shown encouraging activity in chronic myelogenous leukemia (CML).

EXPERIMENTAL DESIGN

We treated 237 patients (median age, 50 years; age range, 18-82 years) with Philadelphia chromosome (Ph)-positive accelerated-phase CML with oral imatinib mesylate at daily doses of 400 mg (26 patients) or 600 mg (211 patients) and evaluated response and survival characteristics in univariate and multivariate analyses.

RESULTS

Among the 200 patients with accelerated-phase CML for whom follow-up was 3 months or more, rates of complete and partial hematological response were 80% and 10%. Cytogenetic responses were evident in 90 patients [45%; complete response in 47 patients (24%) and partial response (Ph 1-34%) in 21 patients (11%)]. The estimated 18-month survival rate was 73%. The estimated complete hematological response rate at 18 months was 68%; that for cytogenetic response was 82%. In multivariate analyses, a diagnosis-to-treatment interval of 3 years or more, splenomegaly, and peripheral blasts predicted poor major cytogenetic response; age >60 years, marrow basophilia, and clonal evolution predicted poor survival. The 600-mg drug dose was associated with better cytogenetic response and survival in univariate analysis (P < 0.01) but not in multivariate analysis. Landmark analysis showed that achieving a cytogenetic response at 3 months or a major cytogenetic response (Ph < 35%) at 6 months was associated with better long-term survival. Seven of 15 patients who were in a second chronic phase achieved major cytogenetic response. The incidence of severe nonhematological toxic effects was 23%; drug discontinuation for severe toxicity was needed in 3% of patients.

CONCLUSIONS

Imatinib mesylate was active against Ph-positive, accelerated-phase CML, and the prognostic factors identified in this study could aid in tailoring treatment strategies to specific risk groups.

Abnormality of c-kit oncoprotein in certain patients with chronic myelogenous leukemia--potential clinical significance

Chronic myelogenous leukemia (CML) is characterized by the Philadelphia (Ph) chromosome and bcr/abl gene rearrangement which occurs in pluripotent hematopoietic progenitor cells expressing the c-kit receptor tyrosine kinase (KIT). To elucidate the biological properties of KIT in CML leukemogenesis, we performed analysis of alterations of the c-kit gene and functional analysis of altered KIT proteins. Gene alterations in the c-kit juxtamembrane domain of 80 CML cases were analyzed by reverse transcriptase and polymerase chain reaction-single strand conformation polymorphism (RT-PCR-SSCP). One case had an abnormality at codon 564 (AAT --> AAG, Asn --> Lys), and six cases had the same base abnormality at codon 541 (ATG --> CTG, Met --> Leu) in the juxtamembrane domain. Because the change from Met to Leu at codon 541 was a conservative one which was also observed in the normal population and normal tissues of CML patients, it probably represents a polymorphic variation. Although samples of hair roots and leukemic cells from the chronic phase of one CML patient showed no abnormality, an abnormality at codon 541 (ATG --> CTG, Met --> Leu) was found only at blastic crisis (BC) of this case. In the case with the abnormality at codon 564, the mutation was detected only in a sample of leukemic cells collected at BC. To examine the biological consequence and biological significance of these abnormalities, murine KIT(L540) and KIT(K563) expression vectors were introduced into interleukin-3 (IL-3)-dependent murine Ba/F3 cells to study their state of tyrosine phosphorylation and their growth rate. Ba/F3 cells expressing KIT(WT), KIT(L540) and KIT(K563) showed dose-dependent tyrosine phosphorylation after treatment with increasing concentrations of recombinant mouse stem cell factor (rmSCF). The cells expressing KIT(L540) and KIT(K563) were found to have greater tyrosine phosphorylation than cells expressing KIT(WT) at 0.1 and 1.0 ng/ml of rmSCF. The Ba/F3 cells expressing KIT(K563) proliferated in response to 0.1 and 1.0 ng/ml of rmSCF as well as IL-3. The Ba/F3 cells expressing KIT(L540)showed a relatively higher proliferative response to 0.1 ng/ml of rmSCF than the response of cells expressing KIT(WT). These mutations and in vitro functional analyses raise the possibility that the KIT abnormalities influence the white blood cell counts (P < 0.05) and survival (P < 0.04) of CML patients.

Susceptibility of nonpromoter CpG islands to de novo methylation in normal and neoplastic cells

BACKGROUND

Many cancers display alterations in methylation patterns of CpG islands--stretches of DNA rich in CpG dinucleotides often associated with gene promoters that are involved in initiation of gene transcription. This methylation may perturb expression of genes critical to the regulation of cell proliferation. Aberrant methylation is not limited to a few genes or to promoter regions but has been found on a genome-wide scale in a variety of neoplasias, including colorectal cancer and acute myelogenous leukemia. Our goal was to characterize, in a quantitative manner, the profiles of abnormally methylated genes that may be specific for different cancers.

METHODS

Using a quantitative assay, methylation-sensitive single nucleotide primer extension (MS-SNuPE), we have analyzed the methylation levels of promoter and exonic (coding region) CpG islands of two cyclin-dependent kinase inhibitors [p15(INK4B) and p16(INK4A)] and the PAX6 gene, which encodes a transcriptional factor involved in neuronal proliferation, in DNA samples taken from patients with chronic myelogenous leukemia, acute myelogenous leukemia, myelodysplastic syndrome, and colorectal cancer.

RESULTS

De novo methylation of all three exonic loci in tumors--relative to baseline levels found in nontumor tissue or blood--was observed in hematologic neoplasias and in solid tumors as well as in normal colonic tissue. However, methylation of promoter regions was more limited. Moreover, two different patterns of promoter methylation distinguished the leukemias from colorectal cancer: p15 promoter hypermethylation was found only in the leukemias, and p16 promoter hypermethylation occurred only in colon tumors. However, we did not address this issue prospectively; therefore, such an observation is only hypothesis generating.

CONCLUSIONS

The methylation patterns that we observed suggest that exonic CpG islands are more susceptible to de novo methylation than promoter islands and that methylation may be seeded in exonic regions, from which it can spread to other islands, including promoter regions. Subsequent selection of cells with a growth advantage conferred by spread of methylation into and inactivation of a particular promoter might then contribute to the genesis of a specific type of cancer.

Molecular biology of chronic myeloid leukemia

Multistep carcinogenesis is exemplified by chronic myeloid leukemia with clinical manifestation consisting of a chronic phase and blast crisis. Pathological generation of BCR-ABL (breakpoint cluster region-Abelson) results in growth promotion, differentiation, resistance to apoptosis, and defect in DNA repair in targeted blood cells. Domains in BCR and ABL sequences work in concert to elicit a variety of leukemogenic signals including Ras, STAT5 (signal transducer and activator of transcription-5), Myc, cyclin D1, P13 (phosphatidylinositol 3-kinase), RIN1 (Ras interaction/interference), and activation of actin cytoskeleton. However, the mechanism of differentiation of transformed cells is poorly understood. A mutator phenotype of BCR-ABL could explain the transformation to blast crisis. The aim of this review is to integrate molecular and biological information on BCR, ABL, and BCR-ABL and to focus on how signaling from those molecules mirrors the biological phenotypes of chronic myeloid leukemia.

A case of near-triploidy in chronic myelogenous leukemia

A 61-year-old woman with chronic myelogenous leukemia (CML) in accelerated phase had a near-triploid bone-marrow karyotype. This karyotype is an unusual finding in CML, as we review 12 previously published similar cases. These patients do not differ clinically from other patients with CML in blast crisis. The cytogenetic features of near-diploid and near-triploid CML are similar, except that relative loss of chromosomes is more common and that isochromosome 17q has not been reported in near-triploid CML.

A successful cord blood transplant in a child with second accelerated phase chronic myeloid leukemia following lymphoid blast crisis

We describe a 5-year-old girl with Ph(+) CML who received a cord blood transplant in a second accelerated phase after a very early lymphoid blast crisis. She was induced into CR by ALL-directed chemotherapy and then maintained with IFN-alpha2b together with weekly rotational chemotherapy. Nineteen months after diagnosis, her mother gave birth to an HLA-compatible sibling, whose cord blood was cryopreserved. The patient's second acceleration occurred 22 months after the CML diagnosis. The subsequent conditioning regimen included busulfan 16 mg/kg, Ara-C 12 g/m2 and melphalan 140 mg/m2. In order to prevent GVHD, CsA alone was administered, 3 mg/kg i.v. per day for a total of 40 days. The total number of nucleated cells infused was 0.8 x 108/kg, with CD34+ cells 1.8 x 106/kg and CFU-GM 1 x 104/kg. Engraftment occurred on day +35. Respiratory distress, severe VOD and grade II acute gastrointestinal GVHD complicated the post-transplant period. No chronic GVHD occurred. The girl is alive 23 months after transplantation with complete donor chimerism; both Ph chromosome and bcr/abl RNA are negative. Bone Marrow Transplantation (2000) 25, 213-215.

The TGF-beta type II receptor in chronic myeloid leukemia: analysis of microsatellite regions and gene expression

Genomic instability is one mechanism proposed to play a role in the disease progression of chronic myeloid leukemia (CML). Microsatellite regions in the type II transforming growth factor-beta receptor (TGF-beta RII) gene appear to be targets for mutation in some cancers displaying microsatellite instability (replication error phenotype, RER+). Furthermore, TGF-beta RII mutations in RER+ tumors have been associated with decreased TGF-beta RII mRNA levels. As TGF-beta is a potent negative growth regulator of hematopoietic cells, investigations were undertaken to determine whether inactivation of the receptor by microsatellite alteration might be involved in the progression of CML. Analysis of TGF-beta RII mRNA expression by RNase protection, with comparison of cells from the chronic, accelerated and blast phases of CML, showed no change in TGF-beta RII transcript levels during disease progression. However, during each phase of the disease, low levels of TGF-beta RII were detected when compared with the hematopoietic cells of normal donors. Furthermore, this decreased expression was also observed in the other myeloproliferative disorders, polycythemia rubra vera (PRV) and essential thrombocythemia (ET). The leukemia cell lines K562 and HL-60 had no detectable TGF-beta RII mRNA. Two microsatellite regions found altered in RER+ colon cancers were analyzed to establish if these sequences were aberrant in CML. No alteration was detected in either of these regions in any phase of the disease. These results suggest that alterations of the microsatellite regions in the TGF-beta RII gene are not involved in the progression of CML. Decreased expression of TGF-beta RII in CML cells and leukemia cell lines raises the possibility that altered expression of the receptor may play a role in the initiation and/or maintenance of the disease state.

[Expression of bcl-2 gene in the evolution of chronic myelogenous leukemia to blast crisis and its implication]

OBJECTIVE

To investigate the expression of bcl-2 gene and cell apoptosis and cell cycle in bone marrow of chronic myelogenous leukemia (CML).

METHODS

APAAP assay and in situ hybridization were used for the expression of BCL-2 protein and bcl-2 mRNA in fresh bone marrow samples from 60 cases of CML. Flow cytometry was used to assess the extent of apoptosis and cell cycle percentage.

RESULTS

The expression of bcl-2 gene had no statistical difference between CMLs at presentation and in chronic phase, but was much lower in blast crisis (P < 0.05). The percentage of bcl-2 mRNA positive cells was consistent with BCL-2 protein expression. In addition, BCL-2 protein was related to the Hb levels, BPC, and immature cells in the peripheral blood and bone marrow. Notably, the extent of apoptosis in accelerated phase/blast crisis was much lower than that in chronic phase(P = 0.028), while the cell cycle had no difference.

CONCLUSION

High level of bcl-2 gene expression and low extent of apoptosis in bone marrow cells of CML might partially be the mechanism of poor prognosis of blast crisis, and this provides a new experimental basis for early diagnosis and treatment of CML blast crisis.

Chromosome band 1p36 contains a putative tumor suppressor gene important in the evolution of chronic myelocytic leukemia

Chronic myelocytic leukemia (CML) is a common neoplasm of hematopoietic pluripotent stem cells. Although the evolution from chronic phase to blast crisis (BC) in CML patients is an inevitable clinical feature, little is understood about the mechanisms responsible for the transformation. We have previously performed allelotype analysis in CML BC and have detected frequent loss of heterozygosity (LOH) on the short arm of chromosome 1. To know the common region of LOH where a putative tumor suppressor gene may reside, deletional mapping was performed using 33 microsatellite markers spanning chromosome 1 in 30 patients with CML BC (21 myeloid and 9 lymphoid). DNA was extracted from slides of bone marrow smears or from bone marrow mononuclear cells. In each patient, DNA from chronic phase was analyzed alongside DNA from either their BC or accelerated phase. Allelic loss on 1p was observed in 14 of the 30 individuals (47%): 10 of the 21 myeloid and 4 of the 9 lymphoid BC cases. Serial cytogenetic information was available in 10 cases with LOH on 1p; interestingly, deletions in this region were not detected. Two samples showed LOH at all informative loci on 1p, whereas the other 12 samples showed LOH on at least one but not all loci on 1p. The common region of LOH resided proximal to D1S508 and distal to D1S507 (1p36). Our results suggest that a tumor suppressor gene that frequently plays an important role in the evolution to BC resides on 1p36 in CML.

Relapsed chronic myeloid leukemia in accelerated phase 10 years after allogeneic bone marrow transplantation: full chimera reconversion with donor peripheral blood stem cells infusion

We report the case of a 44-year-old male who relapsed in accelerated phase chronic myeloid leukemia 10 years after a successful bone marrow transplantation from his HLA-identical brother, and 3 years after 12 months treatment with interferon-alpha (IFN-alpha) for chronic active hepatitis C (CAH). The patient was infused with G-CSF-primed peripheral blood cells (PBSC) from the original bone marrow donor and a full donor reconstitution, with no detectable molecular disease, was obtained within 4 months without clinical aplasia or GVHD, nor help from other forms of chemotherapy or use of biological response modifiers. We speculate that IFN-alpha for CAH delayed the onset of a clinical recurrence of chronic myeloid leukemia and that in advanced disease PBSCs can provide an advantageous alternative to donor lymphocyte infusion (DLI).

Chronic myelocytic leukemia in accelerated phase with i(17) (q10) and loss of p53 gene. Case report

Chronic myelogenous leukemia (CML) is a clonal disorder that presents with a stable period followed by an accelerated phase. The most frequent chromosomal abnormality described is t(9;22). Alterations of chromosome 17, where p53 is located, have been described during transformation. We studied a 23-year-old male who presented with chronic myelogenous leukemia. The karyotype demonstrated 46,XY,t(9;22) (q34;q11) in 12% of mitoses and hyperdiploidy in 43%. Forty-six months later the patient suffered a blast crisis characterized by absolute basophilia; the cytogenetic study demonstrated 48,XY,+8,t(9;22) (q34;q11), +der(22)t (9;22) (q34;q11), +i(17)(q10) in 18% of the mitoses, 46,XY, t(9;22) (q34;q11) in 34% and hyperdiploidy in 23%. Since there was i(17)(q10) during this stage, a retrospective DNA study of the biopsy material before and after the transformation was performed. In the chronic phase, p53 was present in normal amounts, during transformation there was loss of genetic material from the p53 region. The protein product of suppressor gene p53 normally works holding the proliferation of cells. When there is the formation of an isochromosome, genetic material is lost; thus, in this patient, p53 was deleted upon the observation of i(17). Lastly, this case shows how DNA can be extracted from slides; this technique is novel and can be used for retrospective studies when paraffin blocks or fresh tissue are not available.

[The methylation of CT gene in chronic myeloid leukemia]

To investigate the relationship between the abnormal methylation of the calcitonin (CT) gene and the karyotypic abnormality in predicting the disease progress in chronic myeloid leukemia (CML), we studied the abnormal methylation of the CT gene in 47 CML patients by using a sensitive PCR method. At the same time, cytogenetic study was made in the same group of patients. The abnormal methylation of CT gene was found in only 4 of 24 patients in chronic phase, but in 6 of 9 patients in accelerated phase, and in 12 of 14 patients in blast crisis. Sequential studies in one patient also showed that the gene is normally methylated during the chronic phase but turns hypermethylated as the disease progresses. Our findings indicate that abnormal methylation of the 5' region of the CT gene is regularly a marker of disease progression in CML.

Gene structure, promoter activity, and chromosomal location of the DR-nm23 gene, a related member of the nm23 gene family

DR-nm23 cDNA was cloned recently by differential screening of a cDNA library derived from chronic myelogenous leukemia-blast crisis primary cells. It is highly homologous to the putative metastasis suppressor nm23-H1 gene and the closely related nm23-H2 gene. When overexpressed in the myeloid precursor 32Dcl3 cell line, it inhibited granulocyte colony-stimulating factor-stimulated granulocytic differentiation and induced apoptosis. We have now found that the expression of DR-nm23 is not restricted to hematopoietic cells but is also detected in an array of solid tumor cell lines, including carcinoma of the breast, colon, and prostate, as well as the glioblastoma cell line T98G. We have also isolated both the gene and its 5'-flanking region and found that DR-nm23 localizes on chromosome 16q13. The gene consists of six exons and five introns. When fused in-frame to the nucleotide sequence for the green fluorescent protein and transfected in SAOS-2 cells, it generates a protein of the predicted size that localizes to the cytoplasm. The 5'-flanking region of DR-nm23 does not contain a canonical TATA box or a CAAT box, but it is G+C rich and contains two binding sites for the developmentally regulated transcription factor activator protein 2 (AP-2). Transient expression assays of DR-nm23 promoter-chloramphenicol acetyltransferase constructs demonstrated that the segment from nucleotides -1028 to +123 has the highest activity in hematopoietic K562 cells and in TK-ts13 hamster fibroblasts. Moreover, AP-2 induced a 3-fold transactivation of the DR-nm23 5'-flanking segment from nucleotides -1676 to +123 and interacted specifically with oligomers containing putative AP-2 binding sites (-936 to -909, and -548 to -519) as indicated by electrophoretic mobility shift assay. Furthermore, nuclear run-on assays from high and low DR-nm23-expressing cells (K562 and CCRF-CEM, respectively) revealed similar transcription rates. Therefore, the regulation of the DR-nm23 gene expression might involve other mechanisms occurring at posttranscriptional and/or translational levels.

[Detection of multidrug resistance in patients with leukemia by using flow cytometry and RNA in situ hybridization]

Multidrug resistance (MDR) in leukemia and the reversal of MDR by cyclosporin A (CsA) in vitro have been studied through intracellular accumulation of daunorubicin (DNR) in leukemic myeloblasts. The study was carried out with real-time flow cytometry and relative expression levels of MDR, which is estimated by RNA in situ hybridization in 26 patients suffering from leukemia. The change of intracellular DNR accumulation in vitro after adding CsA was also analyzed. The results showed that intracellular DNR accumulation in newly diagnosed and treated patients (MDR1 negative) with remission increased significantly than that in refractory and relapsing patients (P < 0.01). Good reversal effect was obtained in refractory patients and MDR1 positive relapsing patients by adding CsA (P < 0.01). It is suggested that MDR detection by the two above-mentioned methods could help to project the chemotherapy schedule clinically, CsA had obvious reversal effect on the drug-resistant leukemic cells in vitro.

BCR-ABL-positive lymphoblastoid cells display limited proliferative capacity under in vitro culture conditions

We studied the kinetics of EBV-transformed B-cell lines from patients with chronic myeloid leukaemia (CML) using RT-PCR for BCR-ABL transcripts and immunoglobulin heavy chain (IgH) gene rearrangements. Peripheral blood mononuclear cells, obtained from four patients with CML in chronic phase and from one in accelerated phase, were incubated with supernatant from the B95-8 EBV producing cell line. In 11/25 (44%) B-cell cultures established we demonstrated the presence of BCR-ABL transcripts at intervals ranging from 32 to 125 d post EBV transformation. In all but two cases, evidence of BCR-ABL transcripts disappeared with time. Cultures were initially polyclonal with respect to IgH rearrangements but became progressively oligoclonal, suggesting the longer-term survival of fewer clones, all of which were BCR-ABL negative. We conclude that BCR-ABL-positive lymphoid cultures can be established in the short term from the majority of patients with CML but they have limited capacity to survive in the longer term. Therefore, in lymphoid cells the presence of the BCR-ABL chimaeric gene appears to confer no survival advantage.

Kinetics of increasing BCR-ABL transcript numbers in chronic myeloid leukemia patients who relapse after bone marrow transplantation

We prospectively studied 98 chronic myeloid leukemia (CML) patients after bone marrow transplantation by competitive polymerase chain reaction to detect and quantify leukemia-specific BCR-ABL mRNA. Of 69 patients who had persistently undetectable, decreasing, or low BCR-ABL levels ( < 50 transcripts/microgram RNA) on sequential analysis, one (1%) subsequently relapsed. Of 29 patients who had increasing or persistently high BCR-ABL (> 50 transcripts/microgram RNA) on sequential analysis, 21 (72%) have relapsed (P < .00001). In 19 patients studied sequentially, a constant logarithmic increase in the number of BCR-ABL transcripts was found before relapse, indicating a constant BCR-ABL transcript doubling time. The doubling time for patients relapsing cytogenetically or into chronic phase (median, 24.7 days) was significantly longer than that of patients relapsing into advanced phases (median, 14.7 days; P = .005). Eight patients were treated for relapse by donor leukocyte transfusions. The doubling time of responders was significantly longer than that of nonresponders (P = .017). We conclude that quantification of BCR-ABL transcripts after bone marrow transplantation (BMT) is valuable in predicting relapse: a more rapid BCR-ABL transcript doubling time before relapse might indicate a more aggressive disease.

The first intron of the BCR gene contains two minor alternative exons

In Philadelphia chromosome (Ph1) positive leukemias, the BCR gene is fused to the ABL gene. The resulting chimeric BCR-ABL oncoproteins are thought to play a central role in the pathogenesis of these diseases. We previously described two exons that can be spliced alternatively to the second BCR exon in place of the first exon to form minor messages. In this paper, we localize the alternative exons to a 4.1 kb BglII fragment in the 5' region of the large first intron of the BCR gene. This genomic structure is of interest because of its analogy to the organization of the ABL gene and because this part of the gene is not affected by the breakpoints occurring in Ph1-positive acute lymphoblastic leukemia (ALL). Using the reverse transcriptase-polymerase chain reaction (RT-PCR), we detected the alternative messages in all cases of chronic myelogenous leukemia (CML) tested, including seven samples in the chronic phase, five in the accelerated phase and nine in the acute phase, as well as in the majority of other samples studied. These findings suggest a functional role for the variant transcripts.

Specific antisense oligomer anti Bcr-abl junctions in chronic myeloid leukemia: a cell cycle analysis and CFU-GM study

Antisense oligonucleotides were used to determine the role of the BCR-ABL gene in the proliferation of chronic myeloid leukaemia (CML) clonogenic cells. Peripheral blood Philadelphia chromosome positive cells were obtained from eight CML patients at diagnosis (chronic phase = 7; accelerated phase = 1). Mononuclear cells were incubated with synthetic antisense 18-mer oligonucleotides complementary to the two different junctions b2a2 or b3a2. The type of junction (b2a2 or b3a2) was previously determined by RT-PCR techniques. Cells incubated for 12 to 14 hours with or without sense oligonucleotides served as controls. After incubation with oligonucleotides, the cell DNA synthesis was analysed by flow cytometry using the BrdUrd/DNA method and the cell plating efficiency in methylcellulose was determined. In six of the seven patients in chronic phase, there was a significant inhibition of CFU-GM production which was only 68.4 +/- 19%; (p < .01) of that found in controls. The S phase index, which depends upon the percentage of S phase cells as well as the fluorescence intensity, was 48 +/- 29% (p < .01) of the control values for the seven patients in chronic phase. Interestingly, for the only CML patient in accelerated phase, antisense oligomers had no inhibitory effect on either the production of CFU-GM or the number of S phase cells. In improving the specificity of oligomers, it might be useful for gene-targeted anti-leukemic therapy and/or bone marrow purging.

Increase of bcr-abl chimeric mRNA expression in tumor cells of patients with chronic myeloid leukemia precedes disease progression

The translocation t(9;22) in chronic myeloid leukemia (CML) generates a bcr-abl fusion gene that codes for an aberrant chimeric mRNA. Cell lines established from CML patients in blast crisis show higher expression of this aberrant bcr-abl transcript than cells from patients in chronic phase of the disease. This observation provided the stimulus to investigate whether increased expression of the aberrant bcr-abl fusion transcript is critical to the progression of CML from chronic phase to blast crisis. We have monitored the bcr-abl mRNA expression in 25 patients by serial quantitative polymerase chain reaction analyses during a follow-up period of 12 to 156 months after diagnosis, with a median observation time of 28 months. In all patients who have shown disease progression to accelerated phase (n = 4) or blast crisis (n = 7), an increase in bcr-abl mRNA expression was detected up to 16 months before laboratory or clinical parameters showed phenotypic transformation of the malignant clone. To investigate whether the elevated levels of bcr-abl mRNA reflected an increase in the proportion of leukemic cells in the samples analyzed or primarily enhanced transcriptional activity of the bcr-abl fusion gene, we performed quantitative analyses of the bcr-abl gene at the DNA level and of the Ph chromosome at the cytogenetic level and compared these data with steady-state bcr-abl mRNA levels. We show that increased levels of the bcr-abl transcript did not reflect increased proportions of leukemic cells but elevated steady-state levels of the chimeric mRNA in the malignant cells before disease progression. Therefore, our data strongly suggest that an increase of the chimeric mRNA expression in the leukemic cells precedes the phenotypic transformation of the malignant clone.

The relationship between secondary chromosomal abnormalities and blast transformation in chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) is a stem cell disorder which progresses from a chronic phase (CP) to an accelerated phase (AP), and/or a blast phase (BP) of myeloid (M) or lymphoid (L) phenotype. This progression is frequently preceded or accompanied by recurring secondary chromosomal abnormalities which are believed to play a role in the transformation. In order to investigate the relationship between the secondary change and the development of BP, we undertook a study using fluorescence in situ hybridization to determine in which cells the secondary abnormalities were present. We observed that in one case of L-BP, the secondary change (trisomy 8) appeared to be in a subclone that was different from the blast cells, as it was absent from the lymphoblasts but present in differentiating erythroid, monocytic and granulocytic cells. In two cases, the secondary change (trisomy 8, extra Ph) probably occurred prior to an acute transforming event as it was present in CP or AP predominantly in differentiated granulocytic or monocytic cells. In one case of M-BP, the secondary change (trisomy 8) probably occurred after the acute transformation, as it appeared in only a subset of the blasts. Lastly, in four cases of L-BP, the secondary change (monosomy 7, extra Ph or hyperdiploidy) was closely associated with the BP as it was present in all of the blasts. The findings indicate that some secondary abnormalities may be directly related to the development of BP and may provide clues to the identity of genes responsible for the acute phase transition. Other abnormalities occurring before, or after the acute transformation or in a different subclone from the acute phase blasts, may be more important for denoting genomic instability than for helping to understand the mechanism of blast transformation.

HLA-B44-directed cytotoxic T cells associated with acute graft-versus-host disease following unrelated bone marrow transplantation

We describe the recipient of a marrow graft from an HLA-serologically identical unrelated donor from whom highly potent host-reactive CTL of donor origin were isolated in association with acute GVHD. Extensive sequence and biochemical analysis of the HLA complex of this donor and recipient revealed several disparities in class I and class II HLA with the potential to be recognized by T cells from the donor or the host. The donor-derived CTL exclusively recognized a class I HLA difference associated with HLA-B44. Nucleotide sequencing of donor and recipient cells revealed that the patient possessed the HLA-B*4402 allele recognized by IEF as B44.2 while the donor possessed HLA-B*4403 (IEF variant B44.1). These alleles differ at one amino acid residue located at position 156 in the alpha 2 domain. The donor-derived CTL were shown to be specific for B44.2 by blocking studies and by the lysis of five different B44.2+ unrelated cell lines, two of which were confirmed by sequencing to be homozygous for B*4402. A host-specific difference involving a HLA-DRB1 allele was not recognized by the CTL, neither did HLA differences unique to the donor HLA-B*4403 and HLA-DQ8 elicit a host response. These data show that certain HLA disparities may be tolerated at the same time that other disparities elicit a potent immunologic response. The chemical nature of the difference, its structural impact, as well as the conditions of transplant appear to influence the type of response which occurs.

High frequency of RAS oncogene mutation in chronic myeloid leukemia patients with myeloblastoma

To determine the role of the mutated RAS oncogene during development into the blast phase, we sequentially analysed RAS oncogene mutations in the bone marrow of 27 patients with chronic myeloid leukemia (CML). DNA from CML patients in chronic and blast phases and nude mouse tumor DNA formed by a tumorigenicity assay (in vivo selection assay) were subjected to the polymerase chain reaction (PCR) and oligonucleotide hybridization. In addition, one patient in the chronic phase and five in the blast phase were also analysed. PCR analysis of DNA from the leukemic patients revealed that 3.6% (1 of 28) and 15.6% (5 of 32) of the patients in the chronic and blast phases, respectively, had RAS mutations. N- or K-RAS oncogene mutations were found mostly in the blast phase (4 of the 5 patients with the RAS oncogene mutation). Of the 5 patients with the RAS oncogene mutation, three developed myeloblastoma, a myeloblast cell tumor, in the blast phase. None of the 28 patients without the RAS mutation developed myeloblastoma. These results suggest that the RAS oncogene mutation occurred in the late stage of the disease and contributed to transformation to the blast phase in some CML patients. The findings also indicate an association between the presence of the RAS mutation and the formation of myeloblastoma.

CML: mechanisms of disease initiation and progression

Chronic myelogenous leukemia (CML) is a hematological stem cell disorder characterized by excessive proliferation of the myeloid lineage. It has a progressive course typified by the transition from the chronic phase to the accelerated phase and on to blast crisis. The hallmark of CML is the translocation between chromosomes 9 and 22 that results in the chimeric BCR-ABL gene encoding p210BCR-ABL. The oncogenic potential of this protein has been validated, and it is believed that it contributes in a critical way to the initiation of CML. However, the secondary genetic forces responsible for the transition from the chronic state to the fully blastic stage are not clear. Evidence for chromosomal instability includes the clonal evolution which characterizes advanced CML. In regard to specific genetic aberrations, sporadic reports have shown alterations in H-RAS, c-MYC, retinoblastoma, and P53 genes, as well as production of p190BCR-ABL during the progression of CML. In addition, we have recently found evidence for excessive interleukin-1 beta production, acting in an autocrine and/or paracrine manner, in the more advanced stages of the disease. Taken together, current data suggest that multiple molecular pathways lead to disease progression, and that distinct subsets of genetic alterations exist in blast crisis patients.

[Use of a chromosome 21 gene library in the identification of a marker chromosome in chronic myeloid leukemia]

The non-isotopic in situ hybridization makes it possible the analysis of, both, numeric and structural chromosome aberrations in interphase nuclei. Moreover, this technique is useful for identification of chromosome markers of unknown origin, frequently present in malignant diseases. In our case, the fluorescent in situ hybridization allowed us, in a CML patient in accelerated phase, to know the origin of a chromosome marker, and then, to state that the patient had a 21 trisomy added to the Philadelphia chromosome.

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.

[i(17q) appearing in acute phase in Ph1-negative, BCR-negative CML]

A 36-year-old woman was referred to our hospital because of splenomegaly in February 1989. The leukocyte count was 55,500/microliter without hiatus leukemicus. The leukocyte alkaline phosphatase score was low (29). The bone marrow showed myeloid hyperplasia (24.8% myeloblasts) but no dysplastic change. The karyotype of the bone marrow cells was 46, XX and a diagnosis of Ph1 (-) CML was made. Treatment with VCR, 6MP and prednisolone made 7-month duration chronic phase, but the abnormal karyotype.[46, XX, i(17q)] gradually increased to 100% of bone marrow cells. The patient died in June 1990. The evidence that not only a BCR rearrangement but also messages of BCR/ABL fusion gene were negative made us able to differentiate this case from Ph1(-), BCR(+) CML. The addition of an i(17q) results in partial monosomy of 17q (17q13;p53 gene) and partial trisomy of 17q (17q11.2-12;G-CSF gene). We examined the rearrangement of p53 gene and G-CSF-dependent tumor cell growth in vitro, demonstrating one allelic loss of p53 gene and independent cell growth on G-CSF respectively. It is thought that in Ph1 (-), BCR (-) CML as well as in Ph1 (+) CML, an i(17q) is related to the progression but not to the initiation of these leukemias. However the precise mechanism, including p53 gene inactivation by point mutation, is still to be elucidated.

Therapy of acute phase chronic myelogenous leukemia with intensive chemotherapy, blood cell autotransplant and cyclosporine A

The expansion of the Philadelphia (Ph) chromosome positive clone in chronic myeloid leukemia (CML) may depend on its capacity to suppress the proliferation of Ph-negative stem cells, but this proliferative advantage might, in certain circumstances, be reversible. Various lines of evidence suggest that Ph-negative cells, albeit in a suppressed state, must still be present. As recently suggested, the expansion of 'putative' normal Ph-negative hemopoietic stem cells might have, in certain circumstances, a proliferative advantage over the Ph clone in CML. This suggests that the treatment of CML with intensive chemotherapy might allow the collection of Ph-negative hemopoietic cells in the early phase of recovery. Eight patients with acute phase chronic myelogenous leukemia (AP-CML) were treated with idarubicin, intermediate dose cytarabine and etoposide. During recovery from bone marrow aplasia, when the white blood cell count reached 0.3-1 x 10(-9), blood cells were collected with 2-5 (median 3) consecutive leukapheresis. In 5/8 patients, these peripheral cells were Ph-negative at the cytogenetic analysis. Moreover, in one case the polymerase chain reaction analysis performed to detect the presence of minimal residual disease in the cells collected by leukapheresis was negative, further confirming that this approach may induce a very high degree of suppression of the Ph-positive clones. After complete recovery, these five patients were subsequently treated with high-dose etoposide, cyclophosphamide and total body radiation (10 Gy, single dose) followed by reinfusion of Ph-negative peripheral blood stem cells. All these patients received cyclosporine A post-autotransplant in an attempt to induce acute graft-versus-host-disease. Three of 5 patients remain in clinical and cytogenetic remission 5-15 months post-transplant. It is concluded that Ph-negative peripheral blood stem cells can be recovered from patients with AP-CML and used successfully to restore Ph-negative hemopoiesis after high dose therapy.

The spectrum of molecular alterations in the evolution of chronic myelocytic leukemia

DNA from 135 patients with chronic myelogenous leukemia (CML) at various clinical stages and Philadelphia (Ph1) chromosome positive acute lymphoblastic leukemia was investigated for alterations in a variety of proto-oncogenes which have been implicated in the evolution of CML from its chronic phase to blast crisis. The most common genetic change found in the evolution of typical Ph1 chromosome positive CML to blast crisis was an alteration of the p53 gene involving either a rearrangement, a deletion, or a point mutation in the coding sequence of the gene. Alterations of the p53 gene were found in the myeloid and the rare megakaryocytic variant of blast crisis but were absent in the lymphoid leukemic transformants. Gross structural alterations were seen in 11 of 54 (20%) of myeloid or unknown phenotypes of blast crisis and in only 1 of 44 chronic phase cases. Eight examples of mutations in the open reading frame of the p53 gene at codons 49, 53, 60, 140, 202, 204, 238, and 239 were observed in blast crisis patients. Mutations in the N-RAS gene were rare in typical blast crisis (2 of 27 cases) but were found in megakaryocytic and Ph1 negative myeloid blast crisis. We concluded that heterogeneous alterations in the p53 gene and occasionally in the N-RAS genes accompany the evolution of chronic phase CML to blast crisis.

No correlation between locations of bcr breakpoints and clinical states in Ph1-positive CML patients

The majority of patients with chronic myelogenous leukemia (CML) have a characteristic reciprocal translocation between chromosome 9 and 22, resulting in the Philadelphia (Ph1) chromosome. During this translocation, the c-abl oncogene on chromosome 9 is transferred to the Ph1 chromosome and linked to a breakpoint cluster region (bcr), which is part of a large bcr gene. This phenomenon results in the formation of a bcr-c-abl fusion gene, which is transcribed into an 8.5 kb chimeric mRNA encoding a 210 kd bcr-c-abl fusion protein. The fusion protein has tyrosine kinase activity implicated in the pathogenesis of CML. The breakpoint near the c-abl locus on chromosome 9 can occur within a large area. In contrast, the breakpoints on chromosome 22 cluster within the bcr region of 5.8 kb. A chronic phase lasts for an average of 2 to 3 years; and, subsequently, most patients enter blast crisis. In the present study, we examined 15 Ph1-positive CML patients (eight in chronic phase, one in accelerated phase, and six in blast crises) as to whether the identifiable difference in the locations of the bcr breakpoints exist between CML patients in chronic phase and those in blast crisis. In seven of eight CML patients in chronic phase, in one in accelerated phase, and in four out of six CML patients in blast crisis, the bcr breakpoints clustered in the 3' portion of the bcr. Thus, we could not find out the correlation between the locations of the bcr breakpoints and the clinical stage of the CML patients. This might imply that blastic transformation in Ph1-positive CML was caused by other mechanisms than the transition of the bcr breakpoints.

Extramedullary blast crisis and hemolytic anemia in a patient with t(3p+;4q-) and rapidly evolving myelogenous leukemia

We have reported the case of a patient with a rapidly evolving myelogenous leukemia associated with hemolytic anemia, extramedullary evolution, and an isolated translocation of the long arm of chromosome 4 to the short arm of chromosome 3. The hemolytic process was primarily extravascular and was not associated with pyruvate kinase or glucose-6-phosphate dehydrogenase deficiency. Although blasts were absent from the peripheral smear and represented less than 10% of the bone marrow myeloid precursors, multiple organs including the heart, liver, lungs, and spleen were infiltrated with blasts at autopsy.

Chromosomal characteristics of Ph-positive chronic myelogenous leukemia in transformation. A study of 23 Chinese patients in Taiwan

Cytogenetic study was performed in the past 3 years on 23 Chinese patients with Philadelphia chromosome (Ph) positive chronic myelogenous leukemia (CML) in transformation; seven were in accelerated phase and 16 in acute blast crisis. Chromosomal abnormalities in addition to Ph were found in three (43%) of the patients at accelerated phase and 14 (88%) of the patients at blast crisis. The common nonrandom chromosomal aberrations were double Ph, trisomy 8, trisomy 19, and trisomy 21, which occurred in 47%, 41%, 35%, and 29%, respectively, of the total patients with extra chromosomal abnormalities. Isochromosome for the long arm of chromosome 17 was found in only one patient. In patients with blast crisis, the type of blast cell was characterized through morphologic, cytochemical, and immunocytochemical studies. Eleven cases were classified as myeloid and five as lymphoid transformation. Trisomy 8, 19, and 21 were detected only in patients with myeloid blast crisis. This study also revealed a high incidence of trisomy 21 and a low incidence of i(17q) in Chinese patients with transformation of CML.

Variability of the molecular defects corresponding to the presence of a Philadelphia chromosome in human hematologic malignancies

By analyzing a total of 107 patients affected by chronic myelogenous leukemia (CML; chronic and blast crisis) or lymphoid and myeloid Philadelphia chromosome (Ph') positive acute leukemias, we have investigated the relationship between the molecular defect on the Ph' chromosome and the associated hematologic phenotype. As expected, approximately half of the Ph' positive acute leukemias showed a breakpoint on chromosome 22 falling outside the "breakpoint cluster region" (bcr) known to be involved in CML. Surprisingly, seven of 80 CML cases in chronic phase also showed rearrangements falling outside the bcr region. In two of these cases the breakpoint on chromosome 22 was mapped between 9 and 12 kb upstream to the bcr region. In another case, the breakpoint was located approximately 16 kb downstream to bcr. In the remaining four cases, the precise position of the rearrangement could not be localized with the available bcr probes. DNAs from patients with CML blast crises showed classical bcr rearrangements. No molecular changes were observed during the progression of the disease in six patients whose DNA from both a chronic and acute phase was available. Our results seem to indicate a greater degree of variability of chromosome 22 breakpoints in CML than previously observed, and the lack of additional rearrangements on the Ph' chromosome in CML blast crises with respect to chronic phase.

Prognostic significance of cytogenetic abnormalities in patients with chronic myelogenous leukemia

The cytogenetic data for 126 patients with Ph-positive chronic myelogenous leukemia (CML) in accelerated phase or blast crisis were analysed for clonal chromosomal abnormalities in addition to the standard Ph prior to allogeneic or syngeneic bone marrow transplantation (BMT). Additional clonal abnormalities were found in 84%, and 14% had a variant Ph (VPh). In decreasing order of frequency, the most common clonal abnormalities were a second Ph, +8, i(17q), -Y and +19. A second Ph, VPh or +8 occurred more frequently in patients who relapsed following BMT than in those who survived disease-free for at least 1 1/2 years. The presence of an i(17q) alone did not correlate with relapse. The patients with a second Ph, VPh or +8 had a median time to relapse of 19 months, and the risk of relapse at 3 years was 73%. Those with other or no additional clonal abnormalities had not reached a median time to relapse and had a 3-year risk of relapse of 31% (p = 0.002). This analysis suggests that specific cytogenetic abnormalities may be useful indicators of resistance to therapy for CML and should be included in proportional hazard models to predict outcome after BMT.

Ring chromosomes in chronic myelogenous leukemia: an ominous finding

Two cases of Philadelphia chromosome positive chronic myelogenous leukemia (CML) demonstrated ring chromosomes. The appearance of the ring coincided with evolution from the stable to the aggressive phase. A literature search yielded six other cases of ring chromosomes in CML; all were in or were entering the aggressive phase of the disease. Thus, as is the case with acute nonlymphocytic leukemia, in CML the finding of an acquired ring chromosome is associated with a poor prognosis.