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Breakpoints on chromosomes 9 and 22 in Philadelphia chromosome-positive chronic myelogenous leukemia (CML). Amplification of rearranged c-abl oncogenes in CML blast crisis.

We surveyed 20 Philadelphia chromosome (Ph1) positive chronic myelogenous leukemia (CML) samples by Southern blot hybridization to determine the location of the breakpoints that occur on chromosomes 9 and 22 in the Ph1 translocation. Only 3 of 20 samples exhibited breakpoints on chromosome 9 within 18 kilobases (kb) of the v-abl homologous sequences. Mapping of these three chromosome 9 breakpoints indicates that each is at a separate location within this 18-kb region, indicating that there are no breakpoint "hot spots" in this area. In contrast, all 20 CML samples exhibited breaks on chromosome 22 within a 5.0-kb Bgl II fragment that lies within the previously described breakpoint cluster region (bcr). Several patients with CML blast crisis exhibiting multiple Ph1 chromosomes/metaphase exhibited amplified and rearranged c-abl-related fragments. These additional Ph1 chromosomes in blast crisis cells do not arise from a second, independent 9:22 translocation but rather result from a duplication of the preexisting Ph1 chromosome.

Cell Line↗

Genetic marking shows that Ph+ cells present in autologous transplants of chronic myelogenous leukemia (CML) contribute to relapse after autologous bone marrow in CML.

Relapse after autologous bone marrow transplantation for chronic myelogenous leukemia (CML) can be due either to the persistence of leukemia cells in systemic tissues following preparative therapy, or due to the persistence of leukemia cells in the autologous marrow used to restore marrow function after intensive therapy. To help distinguish between these two possible causes of relapse, we used safety-modified retroviruses, which contain the bacterial resistance gene NEO, to mark autologous marrow cells that had been collected from patients early in the phase of hematopoietic recovery after in vivo chemotherapy. The cells were then subjected to ex vivo CD34 selection following collection and 30% of the bone marrow were exposed to a safety-modified virus. This marrow was infused after delivery of systemic therapy, which consisted of total body irradiation (1,020 cGy), cyclophosphamide (120 mg/kg), and VP-16 (750 mg/m2). RT PCR assays specific for the bacterial NEO mRNA, which was coded for by the virus, and the bcr-abl mRNA showed that in two evaluable CML patients transplanted with marked cells, sufficient numbers of leukemia cells remained in the infused marrow to contribute to systemic relapse. In addition, both normal and leukemic cells positive for the retroviral transgenome persisted in the systemic circulation of the patients for at least 280 days posttransplant showing that the infused marrow was responsible for the return of hematopoiesis following the preparative therapy. This observation shows that it is possible to use a replication-incompetent safety-modified retrovirus in order to introduce DNA sequences into the hematopoietic cells of patients undergoing autologous bone marrow transplantation. Moreover, this data suggested that additional fractionation procedures will be necessary to reduce the probability of relapse after bone marrow transplantation in at least the advanced stages of the disease in CML patients undergoing autologous bone marrow transplantation procedures.

Antigens, CD↗

Randomized study of the combination of hydroxyurea and interferon alpha versus hydroxyurea monotherapy during the chronic phase of chronic myelogenous leukemia (CML Study II). The German CML Study Group.

It is the long-term goal of the German CML Study Group and of the Süddeutsche Hämoblastosegruppe (SHG) to improve survival of patients with chronic myelogenous leukemia (CML). In a first randomized study (CML Study I) monotherapies with hydroxyurea or interferon alpha (IFN-alpha) were compared with a standard busulfan regimen with regard to duration of the chronic phase and survival. The main results of this study were published, 1-3 and a long-term follow up is planned. In a second randomized study the effect of the combination of IFN-alpha and hydroxyurea versus hydroxyurea monotherapy on survival is being investigated. This paper provides a first preliminary report on the study concept, patient recruitment, state of documentation and initial patients' characteristics 9 months after closure of the study.

Adult↗

Successful pregnancy and delivery in a patient with chronic myelogenous leukemia (CML), and management of CML with leukapheresis during pregnancy: a case report and review of the literature.

Although infrequently seen, the management of cancer during pregnancy can be difficult for patients, their families and physicians. The concomitant occurrence of pregnancy and chronic myelogenous leukemia is uncommon. We describe the successful management of a 26-year-old woman in the first trimester of her pregnancy with chronic myelogenous leukemia (CML) in chronic phase by using only leukapheresis. She was treated with leukapheresis until her delivery at 36 weeks of gestation. The procedure was without significant adverse effects on the patient or fetus. We applied a total of 15 leukapheresis treatments throughout the pregnancy. The patient gave birth vaginally to a healthy 2800 g boy at 36 weeks of gestation. We conclude that leukapheresis may provide an alternative treatment to chemotherapy, alpha-interferon or imatinib in pregnant patients with CML, particularly with concern over their potential teratogenic and other adverse effects.

Adult↗

Studies on the specificity of CML. Report from a CML-workshop.

In a collaboratory study involving eight different laboratories 30 human, mixed lymphocyte culture educated cytotoxic lymphocytes (CTLs) were identified yielding reproducible cytolysis on allogenic lymphocyte target cells without detectable HLA-A, B (and C) antigenic sharing between stimulator and target cells. These CTLs were collected in one laboratory (Aarhus) and tested in parallel against a population sample of 100 unrelated, healthy Danes. The testing was only performed once and 11 CTLs did not discriminate in the population, probably due to transportation damage. On the basis of pairwise comparisons between 19 CTLs, three tentative CML-defined specificities could be recognized. These three groups may have defined monospecific traits of allelic genetic origin as judged by a mutually negative, albeit not significant, correlation and a fit to Hardy-Weinberg equilibrium. The concept of determinants other than the serologically defined HLA antigens recognized by some CTLs can thus still be maintained as can the approach to CML typing tested in this workshop.

Computers↗

Different patterns of chromosome and molecular breakage in classic Ph1 chronic myelogenous leukemia (CML) and variant Ph1 CML.

Variant translocations involving either chromosome 9, chromosome 22, or both with other chromosomes have been reported in about 8% of chronic myelogenous leukemia (CML) patients. In the 22 Ph+ patients studied in our laboratory, two showed variant translocations: t(9;22;11) (q34;q11;q13), and t(9;11) (q34;q11). We compared the pattern of involvement of different chromosomes (and bands) in secondary structural changes in CMLs carrying the t(9;22) (q34;q11) and in the variant translocations. Analysis showed significant differences in the pattern of involvement of different chromosomes and chromosome sites in the secondary structural changes in classic CMLs. This study, thus identifies nonrandomly involved chromosome sites that may be targeted for detailed molecular analysis to obtain an understanding of their role in disease progression. In the variant translocations chromosomes and chromosome bands were nonrandomly involved. Breakpoint cluster region (bcr) of the BCR gene was found to be rearranged in our two cases. We compared the location of molecular breaks within the bcr in classic and variant translocations. We found that translocation breaks occurred more frequently in the 5' region, and less frequently in the 3' region of bcr in variant translocations as compared with classic translocations. The significance of these findings in the etiology of CML is discussed.

Bone Marrow↗

Progress with interferon in CML--results of the MRC UK CML III study.

527 patients with CML were entered into the multicentre randomised MRC CML III study comparing IFN-alpha n1 to standard chemotherapy, either busulphan or hydroxyurea. Haematologic response to IFN as assessed by the level of control of the WCC predicted cytogenetic response to IFN. Cytogenetic response (< 80% Ph + ve) was seen in 22% of all patients randomised, 11% showing major or complete responses. Major cytogenetic response rate was 18% in Sokal low risk patients, 15% in intermediate risk patients but only 4% in high risk patients. Mantel Byar analyses allowing for time to response showed a survival advantage for cytogenetic responders compared to non-responders. In addition, cytogenetic non-responders to IFN did significantly better than chemotherapy-treated patients. Median survival for all patients was 61 months in the IFN treated groups and 41 months in the no-IFN group. For Ph + ve patients only, the median survival was 63 months compared to 43 months. Sub-group analysis comparing busulphan or hydroxyurea treatment in the IFN and no-IFN treatment arms showed a significant advantage for IFN-compared to busulphan, but no significant difference between IFN and hydroxyurea treated patients, although there was a trend favouring IFN. A proposed overview of all randomised trials comparing IFN to hydroxyurea should, by virture of larger numbers, enable a more accurate assessment of the probable benefit of IFN compared to hydroxyurea therapy.

Adult↗

Randomized studies with interferon in chronic myelogenous leukemia (CML) and comparative molecular aspects. German CML Study Group.

Four randomized prospective studies on interferon alpha (IFN) in CML report varying degrees of prolongation of the chronic phase of CML and of survival as compared to conventional therapies. There is agreement that IFN prolongs survival as compared to standard busulfan. There is disagreement, however, as to which degree IFN is superior to hydroxyurea. Whereas the randomized studies of the Italian cooperative group and of the British MRC find a statistically significant survival advantage of IFN over hydroxyurea of about 20 months, this difference is only 10 months in the German randomized study and not significant. One reason for this difference might be the more intensive treatment schedule for the hydroxyurea control group in the German study. Other reasons might be differences in risk profiles between the patient groups studied and in strategies of IFN therapy. About 1% of the human genome consists of retroviral or retroviral-like sequences. By analogy to animal models, endogenous retroviruses might also have pathogenic potential in human disease. The transposon-like structure of retroviruses that enables them to integrate at almost any position in the host genome and the capability of retroviruses to serve as efficient vehicles of cellular genes are in support of a pathogenic potential. Furthermore, particles resembling retroviruses have been observed long ago in human embryonic and malignant tissues and cell lines. Sequence information and the transcriptional activity of the endogenous sequences argue against the possibility that these sequences are only fossil relics of early evolutionary periods. Most of the sequences appear to be inactivated by stop codons or frameshifts, making the genomic localization of open reading frames with biological activity difficult. Up to now, mutagenesis by insertion of retroviral-like sequences in sporadic cases of human disease appears to be the only example of pathogenic relevance of retroviruses in man.

Antineoplastic Agents↗

Molecular heterogeneity in complete cytogenetic responders after interferon-alpha therapy for chronic myelogenous leukemia: low levels of minimal residual disease are associated with continuing remission. German CML Study Group and the UK MRC CML Study Group.

A substantial minority of patients with chronic myelogenous leukemia (CML) achieve a complete response (CR) to treatment with interferon-alpha (IFN), defined as the disappearance of Philadelphia chromosome-positive metaphases. Currently it is unclear how long IFN treatment should be continued for such patients. We used a competitive reverse transcriptase-polymerase chain reaction (RT-PCR) to quantify levels of BCR-ABL transcripts in 297 peripheral blood specimens collected from 54 patients who had achieved CR with IFN. The median duration of observation was 1.9 years (range, 0.3-11.0 years). Total ABL transcripts were quantified as internal control and results were expressed as the ratio BCR-ABL/ABL. All 54 patients had molecular evidence of residual disease, although 3 patients were intermittently PCR negative. The median BCR-ABL/ABL ratio at the time of maximal response for each patient was 0.045% (range, 0%-3. 6%). During the period of observation 14 patients relapsed, 11 cytogenetically to chronic phase disease and 3 directly to blastic phase. The median ratio of BCR-ABL/ABL at maximal response was significantly higher in patients who relapsed than in those who remained in CR (0.49% versus 0.021%, P < 0.0001). Our findings show that the level of residual disease falls with time in complete responders to IFN, but molecular evidence of disease is rarely if ever eliminated. The actual level of minimal residual disease correlates with the probability of relapse. We suggest that for patients who reach CR, IFN should be continued at least until relatively low levels of residual leukemia are achieved. (Blood. 2000;95:62-66)

Adolescent↗

Comparative analysis of two consecutive phase II studies with IFN-alpha and IFN-alpha + ara-C in untreated chronic-phase CML patients. Austrian CML Study Group.

Two consecutive phase II studies with IFN-alpha (n = 55) and with IFN-alpha/ara-C (n = 84) are compared in a retrospective analysis of untreated chronic-phase CML patients. Hematological responses (CHR and PHR) were seen in 76% of patients after IFN-alpha and in 77% after IFN-alpha/ara-C treatment with a higher CHR rate in the latter group (45% versus 54%). Moreover, cytogenetic responses were observed more frequently in the IFN-alpha/ara-C study (44% versus 34%), including a higher rate of complete cytogenetic responses (13% versus 9%). The combined treatment modality induced higher rates of hematotoxicity (e.g. thrombocytopenia: 44% versus 25%) and gastrointestinal side effects (38% versus 15%) as compared to the monotherapy study.

Adolescent↗

Analysis and validation of prognostic factors for CML. German CML Study Group.

The analysis and validation of prognostic factors is a decisive prerequisite with regard to the development and application of risk-adjusted therapies. Among others, the Sokal index 1 and Kantarjian's new staging system 2 were scores set up to assess the survival of every patient individually. By means of 504 Ph- and/or bcr-abl-positive patients of the German CML study I, we tried to validate both scores mentioned above. Whereas Kantarjian's staging system provided rather unsatisfactory results, the discrimination of different risk groups was more promising with respect to the Sokal index. Still, concerning the differentiation between risk groups for the interferon-alpha (IFN-alpha) treated patients of the German study I, the Sokal index also failed. Hence, we applied Cox stepwise regression technique and identified three prognostic factors for the IFN-alpha treated patients, i.e. eosinophils, erythroblasts (both in peripheral blood), and extramedullary manifestations. We developed our own score and found an encouraging 5-y survival rate of 90% (95% confidence interval (CI) 76-100%) for a certain low-risk group of 41 out of 120 IFN-alpha treated patients. With the need to validate our score and, if possible, not only to confirm the above result but also to identify other particular patient groups, we launched the European Prognostic Factors Project (E.P.F.P.). Within this project, our special interest will be dedicated to patient groups who might also benefit from a bone marrow transplantation.

Adolescent↗

Intensive treatment in order to minimize the Ph-positive clone in CML. Danish-Swedish CML Group.

With the rationale that a significant reduction of the malignant clone in CML might prolong time to metamorphosis, intensive treatment was given to patients < or = 55 years. Six months of hydroxyurea and high dose interferon-alpha (IFN-alpha) was followed by one to three courses of intensive chemotherapy. Patients who had a donor were allotransplanted and patients who became Ph-negative in bone marrow were autotransplanted. On 1 May 1995, 160 patients were registered in the study. Fifty-one percent of the patients who received six months IFN-alpha and hydroxyurea had a significant Ph-reduction and 5% became Ph-negative. The corresponding figures after two intensive chemotherapy courses were 47 and 28%, respectively. Twenty-seven of 30 autotransplanted patients have been analysed for Ph. Seventeen have relapsed cytogenetically, while ten are Ph-negative 1-64 + months after ABMT. BMT was performed in 59 patients. The actuarial 6-year survival from diagnosis of all 160 registered patients is 68%, which seems to be better than for age-matched historical controls.

Adolescent↗

Interferon alfa-2c in chronic myelogenous leukemia (CML): hematologic, cytogenetic and molecular-genetic response of patients with chronic phase CML previously resistant to therapy with interferon gamma.

Alpha- and gamma-interferons have been shown to actively suppress hematopoiesis in patients in the chronic phase of chronic myelogenous leukemia in vitro and in vivo. Since both interferons act through different receptors on their hematopoietic target cells, they are expected to be capable of independently inhibiting abnormal blood cell development in patients with chronic myelogenous leukemia. We have utilized recombinant human interferon alfa-2c to treat 11 patients with Philadelphia chromosome positive chronic myelogenous leukemia in chronic phase, who were resistant to previous interferon gamma therapy. Ten of the patients were evaluable for hematologic, cytogenetic and molecular-genetic response following interferon alfa-2c therapy for 6 to 30 months. In 5 patients, IFN alfa-2c treatment failed due to lack of hematologic response. A complete hematologic or partial hematologic response was achieved in the remaining 5 patients. Three of these experienced cytogenetic improvement with reappearence of 100% diploid hematopoietic cells and disappearence of c-abl/bcr rearrangement in one patient. In two patients interferon alfa-2c did not prevent transformation of the disease into an accelerated state or blast crisis, respectively. We conclude that recombinant human interferon alfa-2c may also control hematopoiesis in interferon-gamma resistant chronic myelogenous leukemia patients, although the long-term response will need to be elucidated in further studies.

Adult↗