Biomedical subjects
Publications and source records attributed to R Becher.
This paper reports on seven atypical Philadelphia chromosome translocations in chronic myelocytic leukemia. Three of them, a t(16;22), t(17;22), and t(9;14;22) have already been observed before, while the t(X;9;11;22), t(X;22), t(3;22) and t(3;4;9;22) are newly reported.
The irreversible binding of o,p'-DDD was examined in isolated lung cells, in lung microsomes and in vivo in male New Zealand White rabbits. Non-ciliated bronchiolar (Clara) cells had the highest capacity to bind o,p'-DDD, followed by alveolar type II cells. A fraction of mixed unidentified lung cells was also able to bind o,p'-DDD while no binding was observed in alveolar macrophages. The activation of o,p'-DDD was shown to be mediated by cytochrome P-450 in both lung microsomes and isolated lung cells. In vivo, the binding was preferentially localized in the lung alveolar and bronchiolar regions. The binding of o,p'-DDD observed in vivo may thus be caused by the capacity of several cell types to activate o,p'-DDD.
Estrogen deprivation by aromatase inhibition is an effective treatment in breast cancer. Between October 1986 and March 1988, 91 postmenopausal patients with advanced breast cancer entered a phase II study performed jointly in three center to investigate the new aromatase inhibitor 4-hydroxyandrostenedione. Patients received 500 mg 4-hydroxyandrostenedione intramuscularly (IM) every 2 weeks for 6 weeks, and 250 mg every 2 weeks thereafter. There were two complete (CRs) and 19 partial remissions (PRs) (response rate, 23%). Disease stabilization (no change; NC) was seen in 26 patients, and in 44 patients (48%), disease progression occurred. Duration of the CRs is 20+ months, median durations of PR and NC are 13+ and 8 months, respectively. Receptor status, relapse-free interval, and sites of metastatic lesions did not appear to influence treatment results. However, efficacy of previous tamoxifen treatment favorably predicted response to 4-hydroxyandrostenedione. Serum estradiol levels decreased significantly in patients after 2 weeks of treatment. Side effects were mostly nonspecific and of low degree, requiring discontinuation of treatment in only 3% of the patients. We conclude that aromatase inhibition with 4-hydroxyandrostenedione is efficacious in the treatment of postmenopausal breast cancer.
The Philadelphia chromosome defines chronic myeloid leukemia, and is mostly based on a translocation t(9;22) with a typical BCR-ABL rearrangement which also occurs in so called atypical translocations. The transformation of chronic myeloid leukemia is associated with clonal evolution in 80% of cases. The appearance of an isochromosome 17q unequivocally heralds the onset of a myeloid type of blast crisis. Treatment of Ph-positive CML has still to be considered palliative except for allogeneic bone marrow transplantation. The Philadelphia chromosome is also found in about 20% of patients with acute lymphoblastic leukemia and in about 2% of patients with nonlymphoblastic leukemia. It is associated with a poor prognosis. Molecular and cytogenetic findings help differentiating between de novo acute leukemia and blast crisis of chronic myeloid leukemia.
Seventy-five patients with advanced and intensively pretreated breast cancer received high-dose medroxyprogesterone acetate (MPA) using a schedule consisting of an intramuscular (IM) loading dose (1 g MPA IM days 1 to 10) and an oral maintenance treatment (200 mg/day three times a day) thereafter. A reinduction was performed in part of the responding patients at time of early relapse (1 g MPA IM for 10 consecutive days). MPA serum levels above 100 ng/ml were achieved during induction treatment and maintained for 3 to 4 months during the oral phase of therapy before decreasing to approximately 50 ng/ml. Two complete remissions (duration, 17.2 and 62 months), 15 partial remissions (median duration, 7 months), and 21 cases of disease stabilization (median duration, 5.5 months) were achieved. The median survival time was significantly longer for responders (19.9 months) than nonresponders (4.8 months). Although a higher proportion of postmenopausal patients responded, the remission duration in premenopausal women was remarkably long. Favorable sites of response were soft tissue, lymph nodes, and bone lesions. Reinduction treatment yielded a second response (two partial remissions, three no change) in five of six patients indicating that high-dose conditions were necessary to maintain response. This schedule allows to restrict higher doses of MPA on a long-term basis to responding patients.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Isochromosome (6p) represents a highly characteristic cytogenetic abnormality of human retinoblastoma (RB) cells and may be important for tumor progression. To elucidate the mechanism by which this abnormal chromosome is formed, 24 RB tumors and three cell lines were studied by means of DNA polymorphisms specific for the short arm and the long arm of chromosome 6. Our results indicate that mitotic nondisjunction leading to trisomy 6 precedes the isochromosome formation. The isochromosome may then be formed by transverse division of the centromere or intrachromosomal chromatid exchange.
Explore the source record for details and available documents.
Thirty-five patients with a median age of 55 years (range, 28 to 68 years) and a median Karnofsky status of 80% (range, 40% to 100%) were treated with ifosfamide (1.5 g/m2 plus mesna), methotrexate (40 mg/m2), and 5-fluorouracil (600 mg/m2) intravenously (IV) days 1 and 8 at intervals of 4 weeks. Thirty-four patients had received previous chemotherapy, including anthracyclines in 28 patients. All patients were evaluable for response. A partial remission was achieved in six patients (17%), stable disease in 13 patients (37%), and 16 patients (46%) were unresponsive. Median time to progression was 7 months (range, 4 to 13 months) for partial responders, and 4 months for patients with stable disease. Median survival was 9 months for all patients, 13 months for partial responders, 16 months for no change, and 3 months for progressive disease. Toxicity was tolerable, with myelotoxicity being a dose-limiting factor, mainly in heavily pretreated patients. No treatment-related death occurred. In conclusion, this combination is effective and well tolerated. Ifosfamide is suggested for further evaluation in advanced breast cancer.
In a phase I/II study, 11 patients with myelodysplastic syndromes (MDS) and severe transfusion-dependent cytopenia were treated with recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) to investigate the effects of rhGM-CSF on normal hematopoiesis and leukemic cells. The treatment schedule included dose escalation from 15 micrograms/m2 to 150 micrograms/m2 administered by continuous intravenous (IV) infusion for seven to 14 days and was repeated after a two-week treatment-free interval. The blood leukocyte counts increased dose dependently by 130% to 1,800% in ten patients; a rise of monocytes and eosinophils occurred in seven and six patients, respectively. No sustained increase in reticulocytes or platelets was observed. Lymphocyte counts increased in all patients affecting both T-helper and T-suppressor cells; however, the lymphocytes were not activated as analyzed by the expression of the interleukin-2 receptor. In four of the patients, all with greater than 14% blast cells in the bone marrow, the percentage of bone marrow blast cells increased during treatment with rhGM-CSF. Cytogenetic data indicated induction of both proliferation and differentiation of the leukemic clones by rhGM-CSF. Toxic side effects were minor with slight fever, phlebitis at the infusion site, and bone pain in the minority of patients. In conclusion, rhGM-CSF effectively stimulates hematopoiesis in vivo in patients with myelodysplastic syndromes. However, as the leukemic cell population can be stimulated in patients with a higher initial blast cell count, the combination of rhGM-CSF with other differentiation-inducing or cytotoxic agents has to be considered.
Explore the source record for details and available documents.
Cytogenetic effects of busulfan in vitro were studied in normal bone marrow (nine cases) and Philadelphia chromosome (Ph)-positive cells (10 cases) of patients with chronic myeloid leukemia. The frequency of chromosome aberrations and sister chromatid exchange (SCE) increased dose dependently. While there were no significant differences between normal and leukemic cells with regard to the induction of chromosome aberrations, the frequency of SCE was significantly lower in Ph-positive cells than in normal bone marrow. This difference was not only apparent on the basis of the SCE frequency per cell, but also when the SCE frequency was correlated to the relative chromosome length as shown by the SCE rate per chromosome group. Longitudinal studies of three patients who received long term busulfan treatment did not show a significant change in the frequency of induced SCE. It can be suggested that the lower frequency of induced SCE in Ph-positive cells reveals less sensitivity of the leukemic cells to DNA damage by busulfan. Our data provide evidence for the inability of busulfan treatment to eradicate or even reduce Ph-positive cells in chronic myeloid leukemia. Evaluation of cell proliferation by sister chromatid differentiation shows longer cell cycle times for the Ph-positive cells. Busulfan affected the cell cycle duration of leukemia and normal cells very little.
The frequency of spontaneous sister chromatid exchange was studied in normal marrow derived from 38 healthy donors and 40 untreated patients with chronic phase CML. The sister chromatid exchange frequency was significantly lower in the leukemic cells (range, 2.32 +/- 1.31 to 4.76 +/- 2.37 per metaphase; mean, 3.18 +/- 0.49) than in normal marrow (range, 2.36 +/- 1.44 to 5.54 +/- 2.24 per metaphase; mean, 3.92 +/- 0.72). The contraction status of chromosomes was comparable in normal and Ph-positive metaphases. The reduction of sister chromatid exchange in leukemic cells was seen in all chromosome groups. The analysis of cell cycle specific proliferation according to the typical staining patterns of metaphases due to the number of cell cycles during which bromodesoxyuridine was substituted, revealed longer cell cycle times for the leukemic cells.
Explore the source record for details and available documents.
A total of 32 patients with metastatic breast cancer responding with at least disease stabilization to treatment with two commercially available preparations of medroxyprogesterone acetate (MPA) or one preparation of megestrol acetate (MA) were followed for their plasma concentrations. The MPA and MA were measured by HPLC. MPA from Upjohn and Farmitalia was given to 12 patients (median age, 61 years; median follow-up, 20 weeks) and 8 patients (54 years, 16 weeks), respectively, on a schedule of 1000 mg daily i.m. for 10 days followed by 200 mg t.i.d.p.o. for the remainder of the treatment course. The peak concentrations (means, 163 vs 97 ng/ml), the time to peak levels (medians, 3 vs 10 weeks), and the areas under the concentration curves from time 0 to 24 weeks (means, 2400 vs 1868 ng/ml X weeks) were significantly different in the respective treatment groups (t-test; significance level, 0.05). MA from Bristol-Myers was administered orally in one daily dose of 160 mg throughout the treatment course in 12 patients (median age, 51 years; median follow-up, 20 weeks). A mean MA peak concentration of 218 ng/ml was reached after a median of 7 days. Plateau plasma levels were higher for MA than MPA.
We report on the cytogenetic findings in six cases of acute promyelocytic leukemia, studied in two different cytogenetic laboratories in Germany. A t(15;17) was detected in three cases. This finding reveals that the t(15;17) in acute nonlymphocytic leukemia type FAB M3 also exists in Germany as a nonrandom anomaly and indicates that it occurs with high frequency in this country.
A report is given of three new cases of acute monocytic leukemia, FAB M5a, with a t(8;16)(p11;p13). Two cases showed a marked erythrophagocytosis, including one with phagocytosis of normoblasts and granulocytes. Phagocytosis was absent in the third case. The t(8;16) was the only abnormality in two cases, whereas one case showed clonal evolution with partial trisomy 1q and a deletion of part of the short arms of chromosomes 1 and 3. Treatment results and survival were poor in all cases. A complete remission was achieved in two patients, which lasted only for 3 and 6 months, respectively. In one of these cases a central nervous system relapse occurred. Survival was short, lasting between 1 and 9 months. One patient succumbed to interstitial pneumonitis, a complication of allogeneic bone marrow transplantation without evidence for relapsing leukemia.