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PubMed1993

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.

Blast Crisis↗
PubMed2001

Unrelated donor cord blood transplantation in adults with chronic myelogenous leukemia: results in nine patients from a single institution.

The potential role of unrelated donor cord blood transplantation (UD-CBT) in adults is not well established. We report the results of UD-CBT in nine adult patients with chronic myeloid leukemia (CML). The median age was 27 years (range, 19-41 years), and the median weight was 62 kg (range, 45-78 kg). At transplant, six patients were in chronic phase (five in first, and one in second), two in blast crisis, and one in accelerated phase. Eight had received intensive chemotherapy, and three had undergone autologous peripheral blood hematopoietic stem cell transplantation. Four had received interferon with no cytogenetic response, and only three underwent UD-CBT within 1 year of diagnosis. After serological typing for class I antigens, and high-resolution DNA typing for DRB1, the degree of HLA match between patients and cord blood (CB) units was 4/6 in six cases and 5/6 in three cases. The median number of nucleated cells infused was 1.7 x 10(7)/kg (range, 1.2 to 4.9 x 10(7)/kg), and was above 2 x 10(7)/kg in only two cases. All patients received thiotepa, busulfan, cyclophosphamide and anti-thymocyte globulin as conditioning; cyclosporine and prednisone for graft-versus-host disease (GVHD) prophylaxis; and G-CSF from day +7 until engraftment. All seven evaluable cases engrafted. The median time to reach an absolute neutrophil count > or =0.5 x 10(9)/l and > or =1 x 10(9)/l was 22 days (range, 19-52 days) and 28 days (range, 23-64 days), respectively. In the four patients evaluable for platelet recovery time to levels of > or =20 x 10(9) platelets/l, > or =50 x 10(9) platelets/l, and > or =100 x 10(9) platelets/l, these ranged from 50 to 128 days, 60 to 139 days, and 105 to 167 days, respectively. Three patients developed acute GVHD above grade II, and three of the five patients at risk developed extensive chronic GVHD. Four patients, all transplanted in chronic phase, remain alive in molecular remission more than 18, 19, 24 and 42 months after transplantation. These preliminary results suggest that UD-CBT may be considered a reasonable alternative in adults with CML who lack an appropriate bone marrow donor.

Acute Disease↗
PubMed2002

Clinical significance of cytogenetic analysis in chronic myeloid leukemia (with report of 155 cases).

OBJECTIVE: To explore the relation of cytogenetic changes in patients with chronic myeloid leukemia (CML) to the diagnosis, clinical staging and therapy protocol of the disease. METHODS: According to established diagnostic criteria, 155 CML patients were divided into 3 groups and 3 clinical phases were identified on the basis of their Sokal scores. The bone marrow was obtained for G banding and karyotype analysis. RESULTS: It was found that 148 patients (95.5%) carried Ph1 chromosome. Among the other 7 cases without Ph1 chromosome, 4 were identified as being bcr/abl fusion gene positive. The ratio of additional cytogenetic abnormalities were higher in patients in blast crisis or accelerated phase than in patients in chronic phase. CONCLUSION: CML consists of a group of diseases with high heterogeneity, and the prognoses of the patients mostly depend on the malignancy of the tumor. The occurrence of additional chromosomal abnormality is highly correlative with the risk index and clinical staging of the patients, which may serve prognostic purposes. Conventional cytogenetic analysis may help evaluate the therapeutic effect and make subsequent clinical decisions, and may also facilitate new karyotype identification.

Adolescent↗
PubMed1995

The receptor tyrosine kinase p185HER2 is expressed on a subset of B-lymphoid blasts from patients with acute lymphoblastic leukemia and chronic myelogenous leukemia.

The class I receptor tyrosine kinase (RTK) HER2 is an oncoprotein that is frequently involved in the pathogenesis of tumors of epithelial origin. Here we report mRNA expression in peripheral blood and bone marrow cells from healthy donors in hematopoietic cell lines and leukemic blasts from patients with acute lymphoblastic leukemia (ALL), acute myeloblastic leukemia (AML), chronic lymphoblastic leukemia (CLL), and chronic myeloid leukemia (CML). However, cell surface expression of HER2 protein (p185HER2) was found exclusively on a subset of leukemic cells of the B-lymphoblastic lineage. p185HER2 expression was found on blasts in 2 of 15 samples from infants, 9 of 19 samples from adult patients with C-ALL (CD19+CD10+), and 1 of 2 samples from patients with pro-B ALL (CD19+CD10-), whereas none of the leukemic cells from patients with AML (0/30), T-ALL (0/7), CLL (0/5) (CD19+CD5+), or CML in chronic and accelerated phase (0/5) or in blast crisis with myeloid differentiation (0/14) were positive for p185HER2. However, cells from 3 of 4 patients with CML in B-lymphoid blast crisis (CD19+CD10+) expressed high levels of p185HER2, which was also found on the surface of the CML-derived B-cell lines BV-173 and Nalm-1. Our study shows p185HER2 expression on malignant cells of hematopoietic origin for the first time. Aberrant expression of this oncogenic receptor tyrosine kinase in hematopoietic cell types may be an oncogenic event contributing to the development of a subset of B-lymphoblastic leukemias.

3T3 Cells↗
PubMed1990

The role of alternative splicing patterns of BCR/ABL transcripts in the generation of the blast crisis of chronic myeloid leukaemia.

Three major types of mRNA can be expressed as a result of the Philadelphia translocation, dependent on the position of the break within the BCR gene on chromosome 22. In addition, alternative splicing of the mRNA transcribed from the BCR/ABL fusion gene has been reported and it has been suggested that this may play a role in the generation of the acute phase of Philadelphia positive chronic myeloid leukaemia (CML). We have examined the fusion RNA present in 24 cases of chronic phase CML and 21 cases of patients with CML in blast crisis using the polymerase chain reaction. In no case was it possible to detect the presence of the e1a2 junction which encodes the p190 hybrid protein product. We conclude that the acquisition of the p190 does not play a significant role in the generation of the blast crisis of CML. Neither could we detect a significant difference in the number of cases which simultaneously express both b2a2 and b3a2 junction products in samples isolated from chronic phase and blast crisis. In the series analysed by ethidium bromide stained gels, there was, however, an increase in the percentage of cases expressing the b3a2 junction in the mononuclear cells of blast crisis patients as compared to the white blood cells of patients in chronic phase.

Base Sequence↗
PubMed1987

Interferon alfa-2b in the treatment of chronic myelogenous leukemia.

Thirty-six patients with Philadelphia chromosome-positive CML were treated with interferon alfa-2b for at least 3 months. Thirty-two of the patients had chronic phase disease and four had acute phase disease, one in blast crisis. Patients initially received a daily dose of 4 megaunits/m2 administered subcutaneously; outpatient self administration followed at a dosage decreased in accordance with serially determined blood cell counts. Treatment was continued for 0.5 to 15 months, with a median duration of 7 months. No complete remission was achieved, but hematologic remission occurred in 21 (58%) patients, with partial hematologic remission in an additional 12 (33%). All four patients with acute phase disease failed to respond. Adverse reactions were only significant during the first days of treatment and did not interfere with self administration of the drug. Interferon alfa-2b may prove to be an important alternative therapeutic modality in chronic phase CML.

Adolescent↗
PubMed1999

A Phase I and pharmacokinetic study of temozolomide and cisplatin in patients with advanced solid malignancies.

Temozolomide (TMZ) is an oral imidazotetrazinone that is spontaneously converted to 5-(3-methyltriazen-1-yl)imidazole-4-carboxamide (MTIC) at physiological pH. MTIC methylates DNA at the O6 position of guanine, although this lesion may be repaired by the enzyme O6-alkylguanine-DNA alkyltransferase (AGAT). In this study, TMZ was combined with cisplatin (CDDP), because both agents have single-agent activity against melanoma and other tumor types. Additionally, CDDP has been shown to inactivate AGAT, and subtherapeutic concentrations of CDDP have been shown to increase the sensitivity of leukemic blasts to TMZ. This Phase I study sought to determine the toxicities, recommended dose, and pharmacological profile of the TMZ/CDDP combination. Patients were treated with oral TMZ daily for 5 consecutive days together with CDDP on day 1 (4 h after TMZ) every 4 weeks at the following TMZ (mg/m2/day)/CDDP (mg/m2) dose levels: 100/75, 150/75, 200/75, and 200/100. Plasma samples were obtained on days 1 and 2 to evaluate the pharmacokinetic parameters of TMZ alone and in combination with CDDP. Fifteen patients received a total of 44 courses of TMZ/CDDP. The principal toxicities of the regimen consisted of neutropenia, thrombocytopenia, nausea, and vomiting, which were intolerable in two of six new patients treated at the 200/100 mg/m2 dose level. Of five patients receiving 17 courses at the next lower dose level (200/75 mg/m2), none experienced dose-limiting toxicity. Antitumor activity was observed in patients with non-small cell lung cancer, squamous cell carcinoma of the tongue, and leiomyosarcoma of the uterus. Pharmacokinetic studies of TMZ revealed the following pertinent parameters (mean +/- SD): time to maximum plasma concentration (Tmax) = 1.1+/-0.6 h (day 1) and 1.7+/-0.9 h (day 2); elimination half-life (t1/2) = 1.74+/-0.22 h (day 1) and 2.35+/-0.70 h (day 2); and clearance (Cl(s)/F) = 115+/-27 ml/min/m2 (day 1) and 141+/-109 ml/min/m2 (day 2). TMZ drug exposure, described by the area under the plasma concentration-time curve (AUCinfinity) and the maximum plasma concentration (Cmax), was similar on days 1 and 2. On the basis of these results, the recommended doses for Phase II clinical trials are TMZ 200 mg/m2/day for 5 days with 75 mg/m2 CDDP on day 1, every 4 weeks. The addition of CDDP did not affect the tolerable dose of single-agent TMZ (200 mg/m2/day x 5 days), nor did it substantially alter the pharmacokinetic behavior of TMZ.

Adult↗
PubMed1987

T-independent and T-dependent steps in the murine B cell response to antiimmunoglobulin.

Sepharose-anti-Ig and purified populations of small, high-density B cells have been used to study the formation and function of B lymphoblasts. Sepharose-anti-Ig converts small, Ia-poor B cells with a high-buoyant density to large, Ia-rich, B blasts with a low-buoyant density. We find that this response proceeds efficiently in the absence of IL-4 (BSF-1) as well as most T cells, macrophages, and dendritic cells. Further development of the blasts requires an additional stimulus, such as LPS or the conditioned medium of stimulated EL-4 thymoma cells. Within 6 h, blasts begin to enter S phase and within 24 h most divide. At later times (48-72 h) most of the blasts are actively secreting IgM. Recombinant IL-1, -2, -3, and -4 have little or no effect on the B blasts, and a neutralizing mAb to IL-4 does not block the response to EL-4 Sn. We conclude that Sepharose-anti-Ig induces B cell blastogenesis in a T-independent fashion and that these blasts represent a highly enriched population of cells that respond to distinct, T cell-derived lymphokines.

Animals↗
PubMed1981

Correlations between the clinical course, characteristics of blast cells, and karyotype patterns in chronic myeloid leukemia.

Results of chromosome studies of blood and bone marrow cells from 101 patients with Ph1 positive chronic myeloid leukemia (CML) confirm the assumptions that clinical and morphologic manifestations of the disease correlate with karyotype peculiarities of leukemia cells. Several variants of the clinical course of CML may be distinguished. One is the variant with a short chronic phase and a comparatively long terminal phase. In blastic crisis the blast cells are peroxidase negative and do not possess cytoplasmic inclusions. Acute transformation occurs without any additional chromosome damage. The second, more common form is less severe because of longer chronic phase but it has a short and grave acute stage. The blast cells present definite signs of myeloid differentiation, they have basophilic or neutrophilic cytoplasmic granules and are peroxidase positive. Marker i(17q) often combined with trisomy 8 is a characteristic chromosome abnormality in the terminal stage of this variant. The third type has an extremely long chronic phase but ends in a rapidly progressing severe and resistant to therapy "lymphoid" blastic crisis. Blast cells have typical "lymphoid" morphology, they are peroxidase negative and contain granular PAS positive substance. Various additional chromosome changes appear in the terminal stage. Future studies of a larger series of patients may possibly reveal more CML variants.

Adolescent↗
PubMed1977

Characteristics of blast crisis in chronic granulocytic leukemia.

The terminal phase of most patients with Ph1-positive chronic granulocytic leukemia (i.e., blast crisis) resembles acute leukemia. The clinical and hematologic features of blast crisis in 73 patients with chronic granulocytic leukemia have been reviewed. Two major morphological subgroups, lymphoblastic and myeloblastic, were identified. The lymphoblastic group in general had more profound thrombocytopenia and a greater number of blasts, while the myeloblastic group had more severa anemia. Extramedullary leukemia was documented in 27 patients. In 12 patients extramedullary leukemia preceded or occurred simultaneously with blast crisis in the bone marrow and peripheral blood. On the basis of this study we present hematologic criteria for the diagnosis of blast crisis and emphasize the importance of extramedullary leukemia in heralding the onset of blast crisis.

Blood Cell Count↗
PubMed1993

[Evaluation of cell cycle in acute leukemias and non-Hodgkin's lymphomas in children].

The DNA profile of blast cells was assayed in 61 children with acute leukemias (51 patients) and non-Hodgkins lymphomas (NHL--10 patients). The value of S phase (synthesis of DNA) and G2M phase (mitotic stage) was compared between the subtypes of acute leukemia and lymphoma based on blast cell phenotype. In acute lymphoblastic leukemia (ALL) the lowest S phase of blast cells was seen in null-ALL subtype, the highest in T-ALL. In non-lymphoblastic leukemia (ANLL) the value of S phase was below S phase observed in ALL. B cell NHL showed higher S phase as compared to T-lymphocyte derived NHL cells. Aneuploidy was noted as hyperdiploidy (8 cases), hypodiploidy (4 cases) and two leukemia cell lines (3 ALL patients). The DNA profile as marker of proliferative activity of blastic cells provides an important information associated with the prognosis of patient.

Adolescent↗
PubMed1976

Cell suppression in PPD-induced blast specific response of human peripheral blood lymphocytes.

Secific stimulation of T-cells by PPD was inhibited by their autologous B cells. This inhibition was obtained with B cells separated either by depletion of E-RFC or by elution, with human IgG of lymphocytes bound to Sephadex beads coated with rabbit antibodies anti-human Fab fragments. The suppression was proportional to the number of B cells added to 10(6) T cells incubated with PPD and as previously reported was more marked in the case of B or T cells from BCG-vaccinated subjects with negative skin tests. The suppressive phenomenon required viable B cells and was inhibited by cycloheximide but was not altered by pretreatment of suppressor cells with actinomycin D or colchicine. It seems that B-suppressor cells interfere with recognition of PPD by T cells rather than with the proliferative phase of the specific blast response. Using various surface markers (i.e. Ig, C3 and Fc receptors) it was shown that the suppressor cells represent a subset of Ig-bearing B cells which do not carry Fc receptors.

Antigens↗
PubMed2002

Chronic myelogenous leukemia: mechanisms underlying disease progression.

Chronic myelogenous leukemia (CML), characterized by the BCR-ABL gene rearrangement, has been extensively studied. Significant progress has been made in the area of BCR-ABL-mediated intracellular signaling, which has led to a better understanding of BCR-ABL-mediated clinical features in chronic phase CML. Disease progression and blast crisis CML is associated with characteristic non-random cytogenetic and molecular events. These can be viewed as increased oncogenic activity or loss of tumor suppressor activity. However, what causes transformation and disease progression to blast crisis is only poorly understood. This is in part due to the lack of a good in vivo model of chronic phase CML even though animal models developed over the last few years have started to provide insights into blast crisis development. Thus, additional in vitro and in vivo studies will be needed to provide a complete understanding of the contribution of BCR-ABL and other genes to disease progression and to improve therapeutic approaches for blast crisis CML.

Animals↗
PubMed2005

[Current and new therapeutic strategies in acute myeloid leukemia].

Seventy to 80% of patients with acute myeloid leukemia (AML) achieve complete remission (CR) by chemotherapy, but more than 50% of them then relapse. Phase III clinical trials in the treatment of patients with previously untreated AML and acute promyelocytic leukemia (APL) are ongoing in Japan (JALSG AML 201, APL 204). And continuous efforts are being made to improve the efficacy of chemotherapy. We discussed six topics in the treatment of AML. (1) To determine whether adding the MDR-1 modulator to chemotherapy provided clinical benefits to patients with AML and high-risk myelodysplastic syndrome (MDS), a phase III randomized study was performed using PSC 833. CR rates and overall survival (OS) were not improved by using PSC 833 compared to chemotherapy alone. (2) A large randomized study selectively focused on the G-CSF priming was performed. Among patients in this study attaining CR, the probability of relapse was reduced when they had been assigned to treatment with G-CSF along with induction chemotherapy. The benefit of chemotherapy-sensitization by G-CSF was particularly evident among the intermediate-risk. (3) Fludarabine in addition to Ara-C increases the accumulation of Ara-CTP, which is responsible for the cytotoxic effect in leukemic blasts. In a randomized phase III trial, patients with high-risk MDS or patients with AML were randomized to receive 2 induction courses consisting of Ara-C and G-CSF during and after chemotherapy with or without fludarabine (FLAG versus AG). Although Ara-CTP accumulation in leukemic cells after FLAG was enhanced, the clinical outcome in terms of CR rate, OS, event-free survival, and disease-free survival was not significantly improved by combining fludarabine with Ara-C. (4) Calicheamicin-conjugated humanized anti-CD 33 mouse monoclonal antibody, mylotarg, has recently been introduced. In combined phase II studies of 277 patients with CD 33-positive AML in their first relapse, the overall response rate was 26%. (5) Arsenic trioxide (ATO) has been established as a highly effective therapy for patients with APL, even for those with disease refractory to ATRA. ATO was recently approved in Japan. (6) There has been great interest in developing FLT 3 inhibitors because of the high frequency and poor prognosis of AML patients with mutant FLT 3. Some compounds are currently under development.

Acute Disease↗
PubMed2001

Response to therapy is independently associated with survival prolongation in chronic myelogenous leukemia in the blastic phase.

BACKGROUND: Achievement of minimal tumor burden, such as complete response, has been accepted as a surrogate marker for improved survival in many solid and hematologic carcinomas. Several new agents have been approved recently for orphan disease indications or unmet medical needs, based on response analyses. This has not been the case for chronic myelogenous leukemia in the blastic phase (CML-BP), despite its poor prognosis, because response has not been proven to be a valuable endpoint for survival prolongation. The purpose of this study was to analyze the effect of response in CML-BP on survival prolongation. STUDY GROUP AND METHODS In total, 328 patients with CML-BP referred from 1989 to 1999 were studied; 311 patients received therapy for CML-BP, and 275 were evaluable for response. Blastic phase CML was defined by the presence of 30% or more blasts in the blood or bone marrow, or extramedullary disease. Treatment responses were reviewed and categorized as proposed in previous large studies. Four categoric response groups were defined further based on significant differences in outcome: cytogenetic response, hematologic response, bone marrow improvement, and failure. The association of treatment response with survival was evaluated by multivariate and landmark analyses. RESULTS: The association of response with survival was analyzed among the 275 patients who had evaluable responses, and follow-up information was documented. Univariate analysis of pretreatment characteristics found performance status, hemoglobin levels, platelet counts, peripheral blasts, additional chromosomal abnormalities, and blastic phase morphology as showing significant associations with survival (P < 0.1). A multivariate analysis found platelet counts and blastic morphology as independent significant factors associated with survival (P < 0.05). A landmark analysis conducted at 8 weeks from start of therapy showed the beneficial effect of achieving response on survival prolongation (P < 0.001). A repeat multivariate at the 8-week landmark time in the 240 patients alive at that time, which included pretreatment characteristics and treatment response, confirmed the independent significant association of morphology (P = 0.003), platelet counts (P = 0.04), and response (P < 0.001) with survival. CONCLUSIONS: Response to therapy is a significant independent factor associated with survival prolongation and maybe an acceptable therapeutic endpoint for approving new treatments in CML-BP.

Adolescent↗
PubMed1992

Phase II study of mitoxantrone and 5-azacytidine for accelerated and blast crisis of chronic myelogenous leukemia: a study of the Eastern Cooperative Oncology Group.

A total of 40 evaluable patients were treated for blastic crisis of chronic myelogenous leukemia with mitoxantrone, 12 mg/m2 per day for three days and 5-azacytidine 150 mg/m2 per day for 5 days. Toxicity was primarily hematologic and was manageable. The overall response rate was 23%, including five complete responders, two partial responders, and two with hematologic improvement. Cytogenetic and immunophenotypic characterization of the leukemia was performed on all patients with aspirable bone marrow, and these results were correlated with response and survival, but did not have predictive value once the patient was in blastic crisis. Only initial platelet count (p = 0.02), hemoglobin (p = 0.03), and lower white blood cell count (p = 0.09) were somewhat predictive of response. Lack of hepatic involvement (p = 0.05), lower white blood cell count (0.05), and higher platelet count (p = 0.02) were predictive of prolonged survival. Although response did not strongly correlate with survival, one third of responders were alive at one year. This regimen produces results similar to those of other recently published regimens in this disease. Earlier intervention and more effective therapy is necessary in these patients.

Adult↗
PubMed1993

Successful mafosfamide purging of bone marrow from chronic myelogenous leukemia (CML) cells.

The in vitro sensitivity of human chronic myeloid leukemia-blast crisis and chronic phase (CML-BC and CML-CP, respectively) cells as well as adherent cell-depleted, T lymphocyte-depleted normal bone marrow cells (A-T-NBMC) to various concentrations of mafosfamide (ASTA Z7654), was examined by colony formation assay in the presence of IL-3 and GM-CSF, to test the possibility of purging of BMC from CML cells. Colony formation by CML cells was inhibited more efficiently than by NBMC. After the incubation with 50 micrograms/ml or 100 micrograms/ml of mafosfamide, the growth of leukemic CFU-GM was totally abrogated in 2/11 or 9/11 cases of CML-BC and in 1/7 or 6/7 cases of CML-CP, respectively. At the same time the CFU-GM arising from normal BMC were not inhibited totally with 50 or 100 micrograms/ml of the drug in any of five experiments. CML cells were still unable to form secondary colonies, while normal BMC were capable of regrowth. The CD34+ cells isolated form CML-BC and CML-CP patients were also more susceptible to mafosfamide cytotoxicity in comparison to CD34+ cells derived from NBMC. To confirm the possibility of purging, CML-BC cells were mixed with NBMC (1:1) and incubated with mafosfamide. Finally, the growing colonies were examined for the presence of bcr/abl hybrid gene by reverse transcriptase-Taq polymerase chain reaction (RT-PCR) and specific hybridization. The bcr/abl gene was not detected in the colonies growing after 100 micrograms/ml, and the signal was diminished after incubation with 50 micrograms/ml of mafosfamide, as compared to control. These results strongly suggest that high concentrations of mafosfamide may be useful for the purging of autologous BMC from CML cells.

Antineoplastic Agents↗
PubMed1991

Clonal succession and deletion of bcr/abl sequences in chronic myelogenous leukemia with recurrent lymphoid blast crisis.

The development of cancer is generally believed to occur by a multistep process in which critical genetic defects accumulate in a clone of cells, confer a growth advantage, and result in the emergence of more malignant subclones. This paper describes the clonal origin of cells in a patient with Philadelphia-chromosome negative, M-bcr rearrangement-positive chronic myelogenous leukemia, observed in two episodes of lymphoid blast crisis (BC), the intervening chronic phases (CP), and following allogeneic bone marrow transplantation. Serial analysis of immunoglobulin heavy and kappa light chain (IgJH, IgCK), beta-T-cell receptor (beta-TcR) and bcr major breakpoint cluster region (M-bcr) gene rearrangements was performed. Clonal IgJH rearrangements present in cells of the first lymphoblastic crisis (BC1) were altered during the chronic phase post-treatment (CP1), and were again altered in recurrent blast crisis (BC2). In addition, the M-bcr gene rearrangement present in BC1 and CP1 was absent from cells in BC2. These observations suggest that the course of clinical neoplastic disorders may not always be characterized simply by a hierarchical process of clonal evolution, but may also involve clonal succession of malignant cells. Moreover, the deletion of M-bcr in recurrent BC suggests that bcr/abl may not be essential for the maintenance of cell growth in established BC.

Adult↗