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Appearance of acute leukemia-associated P190BCR-ABL in chronic myelogenous leukemia may correlate with disease progression.

The Philadelphia translocation in chronic myelogenous leukemia (CML) results in the production of a 210 kD BCR-ABL protein. In contrast, in 50% of Philadelphia-positive acute leukemias, the translocation results in the production of a 190 kD BCR-ABL protein. To investigate the hypothesis that the production of P190 may be associated with the progression from chronic phase to blast crisis in CML, we used polymerase chain reaction to analyze blood from 37 patients with accelerated phase/blast crisis CML for the transcripts coding for the P210BCR-ABL and P190BCR-ABL. The mRNA encoding for P210 was detected in all patients. In three patients, mRNA encoding both P210 and P190 was present. In two of these three patients, samples were available from the time of initial diagnosis. Analysis of these samples did not reveal any transcripts for P190. We conclude that in some patients the appearance of P190BCR-ABL may correlate with transformation to a more aggressive, terminal phase of CML.

Adolescent↗

Accelerating cine phase-contrast flow measurements using k-t BLAST and k-t SENSE.

Conventional phase-contrast velocity mapping in the ascending aorta was combined with k-t BLAST and k-t SENSE. Up to 5.3-fold net acceleration was achieved, enabling single breath-hold acquisitions. A standard phase-contrast (PC) sequence with interleaved acquisition of the velocity-encoded segments was modified to collect data in 2 stages, a high-resolution under sampled and a low-resolution fully sampled training stage. In addition, a modification of the k-t reconstruction strategy was tested. This strategy, denoted as "plug-in," incorporates data acquired in the training stage into the final reconstruction for improved data consistency, similar to conventional keyhole. "k-t SENSE plug-in" was found to provide best image quality and most accurate flow quantification. For this strategy, at least 10 training profiles are required to yield accurate stroke volumes (relative deviation <5%) and good image quality. In vivo 2D cine velocity mapping was performed in 6 healthy volunteers with 30-32 cardiac phases (spatial resolution 1.3 x 1.3 x 8-10 mm(3), temporal resolution of 18-38 ms), yielding relative stroke volumes of 106 +/- 18% (mean +/- 2*SD) and 112 +/- 15% for 3.8 x and 5.3 x net accelerations, respectively. In summary, k-t BLAST and k-t SENSE are promising approaches that permit significant scan-time reduction in PC velocity mapping, thus making high-resolution breath-held flow quantification possible.

Algorithms↗

Regulation of the Erk2-Elk1 signaling pathway and megakaryocytic differentiation of Bcr-Abl(+) K562 leukemic cells by Gab2.

In the blast crisis phase of chronic myelogenous leukemia (CML), Bcr-Abl(+) myeloblasts fail to undergo terminal maturation. The extracellular signal-regulated kinase (Erk) mitogen-activated protein (MAP) kinase has been shown to mediate terminal differentiation of myeloid cells. Interestingly, Bcr-Abl(+) CML cell lines established from blast crisis were found to have low Erk MAP kinase activity. In this study, we analyzed the role of the Gab2 docking protein in regulation of the Erk MAP kinase in Bcr-Abl(+) K562 human CML cells. Overexpression of Gab2 in K562 cells resulted in transcriptional activation of the c-fos serum response element (SRE) promoter, whereas overexpression of SHP2, Grb2, and CrkL had no effect. Activation of the c-fos SRE transcriptional activity by Gab2 required tyrosine 604, which is a SHP2 docking site on Gab2, and the SHP2 tyrosine phosphatase activity. Elk1, c-Jun, and CHOP trans-reporting assays indicated that overexpression of Gab2 selectively activated the Erk2-Elk1 signaling pathway. To determine cellular consequences of elevating the Gab2 level in K562 cells, stable cell lines for doxycycline-inducible expression of the wild-type Gab2 (Gab2WT) and an SHP2-binding defective Gab2 (Gab2Tyr604Phe) were established. Analysis of these cell lines indicated that induction of Gab2WT expression, but not Gab2Tyr604Phe expression, led to Erk activation, growth arrest, cell spreading, and enlargement; expression of megakaryocyte/platelet lineage-specific integrins alphaIIb/beta3 (CD41/CD61); and upregulation of RNA for megakaryocyte/platelet proteins. All of these changes are characteristics of megakaryocytic differentiation. Together, these results reveal Gab2 as a limiting signaling component for Erk MAP kinase activation and terminal differentiation of K562 CML cells.

Adaptor Proteins, Signal Transducing↗

Complete remission of accelerated phase chronic myeloid leukemia by treatment with leukemia-reactive cytotoxic T lymphocytes.

Relapse of chronic myeloid leukemia (CML) in chronic phase after allogeneic stem cell transplantation (SCT) can be successfully treated by donor lymphocyte infusion (DLI). However, relapse of accelerated phase CML, blast crisis, or acute leukemia after allogeneic SCT are resistant to DLI in the majority of cases. In vitro-selected and expanded leukemia-reactive T-cell lines may be more effective in inducing an antileukemic response in vivo. To treat a patient with accelerated phase CML after allogeneic SCT, leukemia-reactive cytotoxic T-lymphocyte (CTL) lines were generated from her HLA-identical donor. Using a modification of a limiting dilution assay, T cells were isolated from the donor, selected based on their ability to inhibit the in vitro growth of CML progenitor cells, and subsequently expanded in vitro to generate CTL lines. Three CTL lines were generated that lysed the leukemic cells from the patient and inhibited the growth of leukemic progenitor cells. The CTL did not react with lymphocytes from donor or recipient and did not affect donor hematopoietic progenitor cells. The 3 leukemia-reactive CTL lines were infused at 5-week intervals at a cumulative dose of 3.2 x 10(9) CTL. Shortly after the third infusion, complete eradication of the leukemic cells was observed, as shown by cytogenetic analysis, fluorescence in situ hybridization, molecular analysis of BCR/ABL-mRNA, and chimerism studies. These results show that in vitro cultured leukemia-reactive CTL lines selected on their ability to inhibit the proliferation of leukemic progenitor cells in vitro can be successfully applied to treat accelerated phase CML after allogeneic SCT.

Adult↗

The abnormal p53 proteins expressed in CML cell lines are non-functional.

Inactivation of the tumor suppressor function of the p53 gene is found in association with 20-40% cases of chronic myeloid leukemia (CML) in blast crisis. A common mechanism of p53 inactivation in CML is by complete deletion of one p53 allele in association with a point mutation which produces a mutant p53 protein on the remaining allele. Whether the mutant p53 protein, which is generally expressed at an elevated level, plays any role in the pathogenesis of blastic transformation or in maintaining the neoplastic proliferation, as it does in some solid tumors, is unknown. By using an antisense oligonucleotide approach, we investigated the cellular function of known abnormal forms of p53 protein, both mutant and truncated, expressed in CML cell lines. We found that the introduction of p53 antisense oligonucleotides can specifically inhibit the translation of the p53 mRNA. However, inhibiting p53 expression had no effect on cell proliferation, cell viability, and colony formation. There was no change in cell doubling time when the cells were maintained in serum-free medium (SFM) in the presence of antisense oligonucleotides compared with cells maintained in SFM alone. We conclude that the mutant or truncated p53 proteins expressed in the blast cells of CML have no growth-promoting effect and are not required for cell survival and proliferation. We further speculate that the loss of the tumor suppressor function of p53 might be the only mechanism by which p53 is involved in the transition from chronic phase to blast crisis.

Base Sequence↗

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.

Actuarial Analysis↗

U.S. Food and Drug Administration Drug Approval Summary: conversion of imatinib mesylate (STI571; Gleevec) tablets from accelerated approval to full approval.

UNLABELLED: Imatinib mesylate (Gleevec, Novartis Pharmaceuticals East Manruer, NJ) received accelerated approval on May 10, 2001 for the treatment of patients with chronic myeloid leukemia (CML) in (a) chronic phase after failure of IFN-alpha therapy, (b) accelerated phase, and (c) blast crisis. The accelerated approval was accompanied by a postmarketing commitment by Novartis Pharmaceuticals to continue patient follow-up to determine duration of treatment response and survival. The present review, based on a safety and efficacy report submitted on December 20, 2002, summarizes data applicable to the conversion of these three CML indications to full approval status. RESULTS: Chronic phase CML: Five hundred thirty-two chronic phase CML patients who had not benefited from prior IFN therapy were treated at a starting imatinib mesylate dose of 400 mg p.o. qd; dose escalation to 800 mg p.o. qd was allowed. Patients had received a median of 14 months of IFN therapy at doses > or =25 million IU/wk and were all in late chronic phase, with a median time from diagnosis of 32 months. Median duration of imatinib mesylate treatment was 29 months, with 81% of patients treated for > or =24 months (maximum 31.5 months). Initial favorable treatment responses were sustained. An estimated 87.8% of patients who had a major cytogenetic response maintained their response 2 years after their initial response. After 2 years of treatment, an estimated 85.4% of patients were free of progression to accelerated phase or blast crisis, and the estimated overall survival was 90.8% (95% confidence interval, 88.3-93.2). Accelerated phase CML: Patients enrolled totaled 293: 235 with CML accelerated phase, 48 with relapsed/refractory acute lymphocytic leukemia, 2 with relapsed/refractory acute myelocytic leukemia, and 8 with relapsed/refractory CML in lymphoid blast crisis. Patients received imatinib mesylate 400 or 600 mg p.o. qd. Dose escalation was permitted, to a maximum of 800 mg/d, taken as 400 mg bid. Efficacy results were improved in patients receiving imatinib mesylate 600 mg qd versus patients receiving 400 mg qd. The median duration of hematologic response was 29 versus 17 months and the estimated 24-month maintained hematologic response rate was 61% versus 42%. The median survival of patients treated with imatinib mesylate 600 mg qd was not reached versus 20.9 months for patients receiving 400 mg qd. Estimated 24-month survival rate was 66% versus 46%. The median survival in the advanced leukemia population (acute lymphocytic leukemia, acute myelocytic leukemia, and lymphoid blast crisis) was only 5 months, and only two patients are still on treatment. Blast crisis CML: A total of 260 patients were recruited. The imatinib mesylate dose was initially 400 mg qd (37 patients) but was subsequently increased to 600 mg qd (223 patients). Patients receiving imatinib mesylate 600 mg qd had a higher hematologic response rate than did patients receiving 400 mg (33% versus 16%). Major cytogenetic responses occurred in 15% of the 260 study patients. The overall median survival was 6.9 months: 7.1 months for patients treated with imatinib mesylate 600 mg and 4.7 months for patients receiving imatinib mesylate 400 mg. Estimated 12-month survival rate for all study patients was 32.1% and estimated 24-month survival rate was 18.3%. SAFETY: Imatinib mesylate was generally well tolerated, but relatively frequent reports of common toxicity criteria grade 3/4 neutropenia and thrombocytopenia were encountered. The most frequently reported adverse events included gastrointestinal disturbances, edema, rash, and musculoskeletal complaints. These rarely led to discontinuation of therapy. CONCLUSIONS: The results confirm those of the interim analysis and suggest that imatinib mesylate represents an effective therapeutic agent for the treatment of patients with CML in chronic phase after failure of IFN-alpha therapy, in blast crisis, and in accelerated phase.

Adolescent↗

Alteration in bone marrow adherent layer growth factor expression: a novel mechanism of chronic myelogenous leukemia progression.

Philadelphia chromosome1 positive (Ph1) chronic myelogenous leukemia (CML) is characterized by metamorphosis of the chronic phase to blastic crisis. However, cellular events associated with this transition are poorly understood. To examine the possible participation of hematopoietic growth factors in this process, we studied growth factor expression in adherent layers of bone marrows derived from CML Ph1 patients in various stages of the disease. Interleukin-1 beta (IL-1 beta) and IL-6 mRNA were expressed in five of six patients, and granulocyte-macrophage colony-stimulating factor (GM-CSF) in one of six patients with myeloid/undifferentiated blast crisis. In addition, leukemia inhibitory factor (LIF) expression was increased in four of six patients with myeloid/undifferentiated blast crisis phase of the disease. IL-1 beta was also detected in bone marrow adherent layer conditioned medium from two of these patients. These results were in sharp contrast to the lack of detectable levels of uninduced IL-1 beta, IL-6, and GM-CSF mRNA, in samples derived from 4 patients in lymphoid blastic crisis, 3 in accelerated, and 11 in chronic phases of the disease, or from normal controls. The possibility of a paracrine loop formation, whereby the adherent layers representing the bone marrow stroma are induced to express hematopoietic growth factors, was supported by our finding IL-1 beta mRNA expression in the leukemic blast cells in three of four studied patients in blast crisis and IL-1 beta protein production in seven of eight patients studied. Finally, coculturing CML blast crisis cells onto pre-established adherent layers induced the expression of both IL-1 beta and IL-6 genes. From this preliminary study, it appears that abnormal expression of growth factors is a common event with CML Ph1 progression. We hypothesize that IL-1 beta generated by the transformed malignant clone stimulates the marrow stroma to produce various growth factors, and that this process may play a role in disease progression.

Blast Crisis↗

Studies of P-glycoprotein in chronic myelogenous leukaemia patients: expression, activity and correlations with CD34 antigen.

Over-expression of the P-glycoprotein (Pgp), transmembrane drug efflux pump, has been shown to cause multidrug resistance of tumour cells (MDR). To investigate the clinical significance of Pgp expression for chronic myeloid leukaemia (CML) diagnosis and monitoring we have studied 38 CML patients in various phases of the disease (chronic phase, CP; accelerated phase, AP; blast crisis, BC). Anti-Pgp monoclonal antibody UIC2 and FACScan analysis were used. Pgp functional activity was investigated by evaluation of verapamil influence upon rhodamine 123 efflux from the cells. Correlations between Pgp and CD34 expression were investigated. In CP, Pgp-expressing cells were found in 2/14 patients; in one of them Pgp proved to be non-functional. There were few Pgp-expressing cells in AP cases. The group of BC patients consisted of cases resistant to chemotherapy. This gave us the opportunity to consider whether drug resistance of BC CML patients is preferentially connected with Pgp-mediated MDR. 11/22 BC patients had 20% or more of Pgp-expressing blasts in the peripheral blood. In all four Pgp+ BC cases studied for Pgp activity this protein was functional. Only 4/22 BC patients demonstrated large (40% or more) fractions of Pgp+ blasts. Moreover, sequential studies of 11 BC CML patients during treatment revealed an increase in the number of Pgp-expressing cells in only two cases. This suggests that Pgp+ cells did not often accumulate in BC CML patients due to chemotherapy and are the cause of drug resistance in only a few cases. A positive correlation between Pgp and CD34 expression was found (r = 0.69; P = 0.0004). 3/22 BC CML patients had large fractions of both Pgp+ and CD34+ blasts in their peripheral blood. The BC CML patients with this immunophenotype of blast cells may represent a subtype of BC CML resistant to treatment due to Pgp overexpression.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Molecular alterations in the TP53 gene of peripheral blood cells of patients with chronic myeloid leukemia.

The TP53 gene has been extensively studied in patients with chronic myeloid leukemia (CML), both in chronic phase and in blast crisis. Mutations in the gene were found in up to 30% of the patients, especially among those in blast crisis. We report the results of an analysis of 29 blood samples from CML patients: 8 samples from chronic phase patients, 8 from patients in the accelerated phase, and 13 from patients in blast crisis. By using genomic DNA, we sequenced PCR products of the coding exons and most introns of the TP53 gene, finding genetic changes in 30% of the blast crisis samples and 12% in chronic phase. All mutations were found in introns and were previously unreported. Immunocytochemical studies revealed accumulation of TP53 in blood cells of samples both from chronic phase and blast crisis patients. Since these samples had no TP53 mutations, we believe that wild type TP53 accumulates in blood cells of CML patients. Our results, therefore, indicate that molecular changes in coding regions of the TP53 gene are rare. The significance of the abundance of intronic changes should be investigated further. Accumulation of wild type TP53 in CML cells may indicate an additional mechanism involving this gene in the pathogenesis of this disease.

Adult↗

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.

Animals↗

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.

Adult↗

Use of interferon alfa-2a to treat hematologic relapse of chronic myelogenous leukemia after bone marrow transplantation.

The use of recombinant human alpha interferon (IFN) to treat relapse of chronic myelogenous leukemia (CML) in chronic phase after bone marrow transplantation (BMT) was studied in a prospective trial. Relapse was defined as > 90% metaphases containing the Philadelphia chromosome (Ph) and hematologic abnormalities consistent with chronic phase CML. In the initial 18 patients, all received allogeneic marrow, 17 from a related donor, 1 from an unrelated donor. Only 1 patient received T-depleted marrow initially. Three patients had relapsed after second BMT. IFN was started at 3 x 10(6) IU/m2/day and escalated to the maximum tolerated dose or to a maximum of 6 x 10(6) IU/m2/day. Elevated white blood counts and platelet counts were controlled in 14 of 16 and 6 of 6 patients, respectively. Six patients (33%) have had a complete disappearance of the Ph (cytogenetic complete response) and 2 have had a partial response (cytogenetic partial response < 35% Ph+ metaphases but > 0%) on at least one sample. Six patients had no significant response after 9-12 months and 4 patients developed clinical accelerated phase or blast crisis after 3-6 months. IFN controlled the blood counts in 75% of patients. Of 4 patients with a sex marker, the Ph- population was of donor origin in 3 and of host origin in 1. Clonal cytogenetic abnormalities other than the Ph were present in 13 patients and did not predict for lack of response to IFN. IFN effectively produces hematologic control in the majority of patients and suppresses the Ph clone in up to one third. A trial of IFN treatment in an earlier stage of relapse is indicated.

Blast Crisis↗

Chronic myelogenous leukaemia (CML): an update.

The management of chronic myelogenous leukaemia (CML) has undergone a major change over the past 5 years. All newly diagnosed patients of CML are candidates for imatinib mesylate therapy. Almost 95% of patients with early chronic phase CML achieve complete haematological remission (CHR) and nearly 80% achieve complete cytogenetic response (CGR; 0% Philadelphia [Ph] chromosome-positive metaphases). These responses are stable in most patients with a risk of relapse of 4%-6% per year. For patients with advanced CML (accelerated phase and blast crisis), achievement of CHR and major (complete and partial) CGR occurs in 25%-37% and 10%-30% of patients, respectively. Most investigators agree that patients who fail to achieve CHR by 12 weeks, have partial cytogenetic response (< 35% Ph-positive metaphases) at 12 months, have CGR by 18 months, who relapse after initial response to imatinib, and those with a high Sokal score or in an advanced phase of CML should be considered for allogeneic stem cell transplantation (SCT). Despite Ph negativity with imatinib treatment, most patients continue to remain BCR-ABL positive on molecular studies, and require treatment indefinitely. Identification of patients at high risk for relapse and understanding the mechanisms to unravel resistance to imatinib are current areas of active research.

Antineoplastic Agents↗

High and low Fc IgG-receptor expression in human chronic granulocytic leukaemia cells.

Discontinuous density-gradient centrifugation was used to separate chronic granulocytic leukaemia (CGL) cells in the chronic phase and blast crisis (BC) into fractions containing granulocytes in individual stages of maturation. The occurrence of the Fc IgG (FcR) and complement-component receptors (CR1 and CR2) in each fraction was estimated. It was established that, with increasing yields of mature granulocytes, the proportion of cells bearing Fc and C3 receptors increased. The most important finding was that the high- and low-receptor categories of CGL cells in chronic phase depended on the percentage of FcR+ cells. In the high-receptor CGL group, in addition to FcR, the proportion of CR1+ and CR2+ cells was also greater than in the low-receptor CGL group. Some differences in clinical course of both immunological CGL groups were observed.

Adult↗

Allogeneic and syngeneic marrow transplantation following high dose dimethylbusulfan, cyclophosphamide and total body irradiation.

Fifty-eight patients received an allogeneic or syngeneic marrow transplant following conditioning with high doses of dimethylbusulfan (DMB), cyclophosphamide (CY) and total body irradiation (TBI). Thirty-two patients had either chronic myeloid leukemia (CML) in accelerated phase or blast transformation, or acute leukemia after first relapse. The actuarial survival of these 32 patients at 3 years was 12% compared with 25% for a group of 206 patients with similar diagnoses prepared for transplantation with CY and TBI alone. This reduced survival was associated with a greater incidence of early non-leukemic deaths, in particular as a result of severe hepatic veno-occlusive disease. The incidence of leukemic relapse was not different in the two groups. Of 13 patients with CML in chronic phase who received syngeneic transplants following DMB, CY and TBI, nine are alive in hematologic and cytogenetic remission from 3.9 to 9.4 (median 6.2) years post-transplant.

Adolescent↗

[Reversion to chronic phase of chronic myelogenous leukemia in blast crisis with small-dose daunorubicin and oral prednisolone].

In December 1993, a 76-year-old Japanese male presented with general fatigue. Peripheral blood (PB) examination indicated marked leukocytosis (WBC count, 19.8 x 10(4)/microliter; leukemic blast differential, 89.5%). Leukemic blasts were positive for CD33, and negative for lymphoid antigens, with 2% of the blasts being positive for myeloperoxidase staining. On admission, chromosome analysis of leukemic cells in PB showed 45, X,-Y, t (9;22) [12/15]/46, XY, t (9;22) [3/15]. Southern blot analysis of the DNA from PB showed a rearrangement at the M-BCR region and germline configurations of both TCR beta and IgH chain genes. The patient was diagnosed as Philadelphia-positive chronic myelogenous leukemia (CML) in blast crisis. We commenced treatment with daunorubicin (DNR; 20 mg/day x 1 IV) and daily prednisolone (PSL; 60 mg/day PO). Leukemic blasts disappeared rapidly from PB, while the promyelocytes showed a transient increase, peaked 7 days after the start of therapy, and then disappeared. Myelocytes and metamyelocytes also showed transient increases. Without a period of severe myelosuppression, the patient reverted to the chronic phase of CML and karyotypic analysis of bone marrow cells showed 45, X,-Y, t (9;22) [33/35]/46, XY, [2/35]. Consolidation chemotherapy with DNR and BHAC was started, but the patient's condition deteriorated due to bacterial infection and he died of hepatic failure on March 1994. In this case, reversion to the chronic phase of CML in blast crisis may be accomplished by the cytodifferentiating effects of small-dose DNR and oral PSL to the leukemic blasts.

Administration, Oral↗

The BCR/ABL transgene causes abnormal NK cell differentiation and can be found in circulating NK cells of advanced phase chronic myelogenous leukemia patients.

NK cells from the blood of chronic myelogenous leukemia (CML) patients are progressively decreased in number as the disease progresses from chronic phase to blast crisis. We hypothesize that BCR/ABL may be directly responsible by interfering with NK cell differentiation. CD34(+)HLA-DR(+) cells from CML patients were studied for their capacity to differentiate into NK cells. The NK cell cloning frequency was significantly decreased from CML CD34(+)HLA-DR(+) cells compared with cells from normal donors, yet CD34(+)HLA-DR(+) cells gave rise to BCR/ABL(+) NK cells in some patients. This finding prompted us to further investigate circulating NK cells from the blood of CML patients. CD56(+)CD3(-) NK cells were sorted from CML patients and examined by fluorescence in situ hybridization (FISH). In contrast to chronic phase CML, significant numbers of NK cells from advanced phase CML patients were BCR/ABL(+), whereas T cells were always BCR/ABL(-) regardless of the disease stage. To test the effects of BCR/ABL as the sole genetic abnormality, BCR/ABL was transduced into umbilical cord blood CD34(+) cells, and NK development was studied. p210-enhanced green fluorescence protein-transduced cells gave rise to significantly decreased numbers of NK cells compared with enhanced green fluorescence protein transduction alone. In addition, the extrinsic addition of BCR/ABL-transduced autologous CD34(+) cells suppressed the NK cell differentiation of normal umbilical cord blood CD34(+)CD38(-) cells. This study provides the first evidence that BCR/ABL is responsible for the altered differentiation of NK cells and that the NK cell lineage can be involved with the malignant clone in advanced stage CML.

Animals↗