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At least 811 records · Page 45Linked to original sources
PubMed1995

Cyclophosphamide/doxorubicin vs. cisplatin/teniposide in the treatment of children older than 12 months of age with disseminated neuroblastoma: a Pediatric Oncology Group Randomized Phase II study.

This prospective study was designed to estimate the response rates and to compare two drug pairs, cyclophosphamide/doxorubicin (Cy/A) and cisplatin/teniposide (P1/VM) in previously untreated patients with disseminated neuroblastoma > 12 months of age at diagnosis. Estimated complete clinical response rates after five courses of therapy were 13% (70 patients) and 22% (64 patients) for Cy/A and P1/VM, respectively (P = 0.17). After surgical removal of residual tumors in patients with partial response, the complete response rates were 27% and 34% (P = 0.50), respectively. The overall CR/PR rates after induction and surgery were 59% and 73% (P = 0.077). There was no significant difference in event free survival (P = 0.48) or survival (P = 0.40). Five year survival on the two arms were 14% (SE = 5%) and 12% (SE = 4%), respectively. Toxicity was significant but manageable. The Cy/A arm had significantly higher hematopoietic toxicity but significantly lower GI toxicity. Significant allergic reactions were seen with the P1/VM arm, none in the Cy/A arm. Given the activity of these two regimens, further therapy with a combination of these regimens is suggested.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2007

Retinoblastoma in children older than 5 years of age.

BACKGROUND: Retinoblastoma is a malignant tumor of the embryonic neural retina. About 80% of cases are diagnosed before age 4, with a median age at diagnosis of 2 years. OBJECTIVE: To determine characteristics and prognosis of retinoblastoma in children older than 5 years. PROCEDURES: From 1986 to 2002, medical records of 16 patients out of 453 cases referred to Hospital do Câncer AC Camargo, São Paulo, Brazil. RESULTS: Median age at diagnosis was 73.7 months (range 65-144) and there was an equal gender distribution. Fifteen patients presented with unilateral disease. The mean time between first symptoms and diagnosis was 9.6 months (range 0-48). Most cases were diagnosed in advanced stages and 15 eyes were enucleated. Eleven patients presented with intraocular tumor (1 Reese II and 10 Reese V) and five presented with extraocular disease (one CCG II and four CCG III). Twelve patients are still alive with a median follow-up of 92 months (range 65-199). CONCLUSIONS: Because of its low incidence at this age, diagnosis of retinoblastoma is usually delayed due to low level of suspicion. Therefore, it is important that physicians are aware of this disease in order to perform an earlier diagnosis, and decrease treatment-related morbidity.

Age Distribution↗
PubMed1990

Rapid evaluation of topoisomerase inhibitors: caffeine inhibition of topoisomerases in vivo.

Caffeine was found to inhibit both type I and type II topoisomerases in vivo as judged by its effects on replicating simian virus 40 (SV40) chromosomes. The study was facilitated by the use of a rapid filter assay for the detection and characterization of topoisomerase inhibitors. The assay, which requires neither purified enzymes nor substrates, was able to identify both antagonists and poisons of type I and type II topoisomerases.

Animals↗
PubMed1978

Teratogenic and cytogenetic effects of some plant-derived antitumor agents (vincristine, colchicine, maytansine, VP-16-213 and VM-26) in mice.

The teratogenic effects of three new plant-derived antitumor agents, maytansine, VP-16-213 and VM-26, were compared to the effects of vincristine and colchicine in pregnant Swiss albino mice that received a single ip injection of drug on day 6, 7 or 8 of gestation. Cytogenetic studies were also performed using maternal bone marrow and embryos obtained 48 hours after injection of maytansine, vincristine, VP-16-213, VM-26 and colchicine on day 6, 7 or 8 of gestation. A close correlation between teratogenic and cytogenetic effects was not noted among the compounds tested. Vincristine had greater embryotoxic and teratogenic activity than maytansine at equimolar doses (0.36 mu moles/kg), with the peak effects appearing after injection on day 7 of gestation. Colchicine, VP-16-213 and VM-26 were comparatively less potent than maytansine and vincristine, since doses of 2.5 mu moles/kg (colchicine and VP-16-213) and 1.5 mu moles/kg (VM-26) were required to elicit embryotoxic effects. At their teratogenic doses, all compounds induced various cranial abnormalities including exencephaly, hydrocephalus, anophthalmia and microtia, as well as major skeletal malformations. The teratogenic dose of vincristine is comparable to its effective antitumor dose in transplantable rodent tumor systems; in contrast, the teratogenic dose of maytansine in approximately 10-fold higher than its antitumor dose. Of the compounds studied, VP-16-213 and VM-26 exerted the most consistent cytogenetic effects in embryonic tissue. Alarge proportion of the structural chromosome aberrations induced in embryonic cells by VM-26 were stable and are most likely capable of surviving at least one cell division.

Abnormalities, Drug-Induced↗
PubMed1995

Response of purified mitochondrial DNA topoisomerase I from bovine liver to camptothecin and m-AMSA.

The type I DNA topoisomerase isolated from bovine liver mitochondria is demonstrated here to be inhibited by camptothecin, a plant alkaloid previously shown to target the nuclear type I topoisomerase in mammalian cells. The antitumor drug reduces the ability of the mitochondrial enzyme to relax positive as well as negative supercoils although the inhibition of the former process requires more than 60-fold more drug than the latter process. A similar response is seen with the nuclear topoisomerase I. Camptothecin also stimulates the mitochondrial topoisomerase-induced cleavage of pUC19 at numerous, discrete sites. The antitumor drug 4'-(9-acridinylamino)-methanesulfon-m-anisidide, which has been shown to target the nuclear topoisomerase II, inhibited the mitochondrial type I topoisomerase relaxation activity, but this effect was found to be the result of the drug intercalating into the negatively supercoiled DNA rather than from a specific interaction with the mitochondrial enzyme. VM-26, a nonintercalating topoisomerase II poison, showed no inhibitory effect up to a concentration of 50 microM.

Amsacrine↗
PubMed2002

Quantitation of gene-specific DNA damage by competitive PCR.

A sensitive assay for quantitating DNA damage within individual genes would be a valuable tool for identifying the molecular mechanisms of disease and the sites of action of various carcinogens and anticancer drugs. This report describes a competitive PCR assay that was used to quantitate DNA damage induced by anticancer drugs within a 683-bp region of the c-myc gene in human CEM leukemia cells. Absolute quantitation of gene-specific DNA damage (attomoles or molecules of damaged DNA sequences) was achieved by coamplification of a homologous internal standard that has the same primer binding sites and PCR amplification efficiency as c-myc. The variability (standard error) associated with four separate determinations of the amount of c-myc sequence in 300 ng of DNA from untreated cells (6.80 +/- 0.05 SE amol) was less than 1% of the mean. The assay was capable of quantitating direct DNA damage that was induced by therapeutic concentrations of VM-26 and cisplatin prior to the onset of cellular apoptosis or necrosis. Both VM-26 (1-10 microM) and cisplatin (25-100 microM) induced a dose-dependent decrease in the amount of intact c-myc sequence. This assay should be readily adaptable to current real-time PCR protocols.

Antineoplastic Agents↗
PubMed2001

Caspase-dependent chemotherapy-induced death of glioma cells requires mitochondrial cytochrome c release.

Chemotherapeutic drug-induced apoptosis of human malignant glioma cells involves the death receptor-independent activation of caspases other than caspases 3 or 8 (Glaser et al., Oncogene 18, 5044-5053, 1999). Here, we report that caspases 1, 2, 3, 7, 8, and 9 are constitutively expressed in most human malignant glioma cell lines. Cytotoxic drug-induced apoptosisinvolves delayed activation of caspases 2, 7, and 9, but not 8 and 3, and is blocked by a broad spectrum caspase inhibitor, zVAD-fmk. Cytochrome c release from mitochondria precedes caspase activation during drug-induced apoptosis and is unaffected by zVAD-fmk or ectopic expression of the viral caspase inhibitor, crm-A. In contrast, ectopic expression of BCL-X(L) prevents drug-induced cytochrome c release, caspase activation and cell death. Thus, cancer chemotherapy targets the mitochondrial, caspase-dependent death pathway in human malignant glioma cells.

Amino Acid Chloromethyl Ketones↗
PubMed1994

Inhibition of topoisomerase II activity and its effect on nucleolar structure and function.

The relationship between topoisomerase II activity and ribosomal RNA synthesis was investigated using the antitumoral drug VM26, a specific inhibitor of topoisomerase II. For this purpose TG cells, a human tumor cell line, were cultured in the presence of 2.5 microM VM26 for 1 and 3 h; VM26 reduced the topoisomerase II activity, measured in whole cell extracts. In the presence of VM26 the [3H]uridine incorporation into ribosomal RNA was decreased; electron microscopy investigation of nucleoli showed a segregation of nucleolar components. Because VM26 stabilizes the cleavable complex and inhibits the resealing reaction, thus causing potential cleavage sites, we have analyzed the double-strand breaks caused by the drug treatment in the tandem repeat ribosomal DNA (rDNA) genes, by indirect labeling with two probes recognizing the 5' portion of ETS (BES) and the 3' portion of 28S (LS6BE) transcribed gene. In VM26-treated cells rDNA is fragmented and a topoisomerase II preferential cleavage site is present, localized at 1.85 kb in 28S region from 3' EcoRI site.

Cell Nucleolus↗
PubMed1994

Role of topoisomerase II in the structural and functional evolution of mitogen-stimulated lymphocyte nuclei.

To examine the role of DNA topoisomerase II (Topo II) in the mitogenic activation of mouse lymphocytes, we applied the Topo II inhibitor VM26 throughout the stimulation period and monitored morphological and functional parameters of lymphocyte activation. Cell viability and the usual increase in cell size were little affected at doses between 0.05 and 0.5 microM. DNA synthesis, however, was already significantly inhibited at 0.05 microM, with RNA synthesis inhibited to a lesser extent. Light microscope autoradiography showed that a smaller proportion of cells entered S phase, with each S phase cell incorporating less [3H]thymidine. In immunofluorescence studies, the nucleolar antigen fibrillarin was reduced, although only minor effects on the snRNP Sm antigen and the internal component labeled by antibody PI1 were observed. At the electron microscope level, nucleoli were remodeled and chromatin became aggregated. At a high dose of VM26 (5 microM), cells showed the expected high levels of apoptosis and strong inhibition in all activation parameters assayed. The results support the hypothesis that the Topo II beta isoform is involved in the very early phases of lymphocyte activation, with function of the Topo II alpha isoform, which is more sensitive to VM26, being required for progression through S phase.

Animals↗
PubMed1999

Association of human DNA topoisomerase IIalpha with mitotic chromosomes in mammalian cells is independent of its catalytic activity.

DNA topoisomerase (topo) II is an essential nuclear enzyme that plays an important role in DNA metabolism and chromosome organization. In the present study, we expressed human topo IIalpha in mammalian cells by fusion to an enhanced green fluorescent protein (EGFP). Decatenation assays indicated that the EGFP-topo IIalpha is catalytically active in vitro. Assays for band depletion, growth inhibition, and cytotoxicity by topo II inhibitors suggested that the fusion protein is also functional in vivo. By following its subcellular localization throughout the cell cycle in living cells, we found that the fusion protein is localized to the nucleus and nucleolus at interphase, and it is bound to chromosomal DNA at every stage of mitosis. Of importance, a mutant EGFP-topo IIalpha, in which the active Tyr 805 is replaced by Phe (Y805F) and is catalytically inactive, still binds to chromosomal DNA throughout the cell cycle like the wild-type enzyme. Together, our results suggest that the ability of topo IIalpha to bind to chromosomal DNA in the cell, a presumed requirement for its structural role, can be separated from its catalytic activity.

Antigens, Neoplasm↗
PubMed1999

Genomic sites of topoisomerase II activity determined by comparing DNA breakage enhanced by three distinct poisons.

To define the sites of topoisomerase II activity in two genomic regions of Drosophila melanogaster Kc cells, we have investigated in vivo DNA cleavage sites stimulated by three poisons with diverse sequence specificity, clerocidin, VM-26 and dh-EPI (an anthracycline analog). DNA cleavage was studied by PFGE (pulse-field gel electrophoresis), standard gel electrophoresis, and by genomic primer extension. Poisons stimulated specific intensity patterns of cleavage in the two genomic regions studied. At the centromeric satellite III DNA, fragments of about 270-310 and 385-430 kb could be detected specifically after treatment with clerocidin, suggesting a complex DNA loop organisation, which may correspond with a centromere-specific higher-order chromatin structure. Clerocidin-dependent DNA fragmentation was detectable by PFGE but not by standard agarose gel electrophoresis; while VM-26-dependent cleavage was detected with either method, dh-EPI was ineffective at this locus. Thus, clerocidin DNA cleavage sites were rarer than those of VM-26 at the satellite locus. In the histone H2A-H2B intergenic region, clerocidin and dh-EPI stimulated cleavage whereas VM-26 was only weakly effective. Some clerocidin cleavage sites did not undergo spontaneous reversion, indicating that this agent can stimulate irreversible cleavage in vivo. Direct genomic sequencing showed that many clerocidin and dh-EPI sites, although distinct, mapped to the transcription start and to the proximal promoter of the H2A gene, suggesting that the region is highly accessible to topoisomerase II. Thus, the enzyme may play a role in maintaining a highly accessible chromatin structure under normal cell growth conditions, possibly mediated by specialised protein complexes. This study demonstrates that the use of distinct poisons greatly improves the definition of genomic sites of topoisomerase II activity.

Animals↗
PubMed1990

Treatment of relapsed acute lymphocytic leukemia in adults.

Thirty-three patients with ALL/AUL in first relapse were treated with an induction of prednisone, vindesine, daunorubicin, Erwinia asparaginase, i.t. MTX (phase I), high-dose cytarabine, and etoposide (phase II). Twenty-one (64%) achieved a complete remission, one a partial remission. Side effects of induction-phase I were predominantly hematological with subsequent infections and gastrointestinal toxicity. In phase II some patients had additional cutaneous, ocular, and hepatic toxicity. The treatment efficiently induced remissions with tolerable toxicity in relapsed ALL. The disease-free survival, however, needs to be improved.

Adolescent↗
PubMed1977

Treatment of malignant gliomas and brain metastases in adults using a combination of adriamycine, VM 26, and CCNU. Results of a type II trial.

Forty-three patients with inoperable and/or recurring malignant gliomas and 30 patients with multiple recurring brain metastases were treated with a combination of adriamycine (45 mg/m 2 and 4-dimethyl-epipodophyllotoxin D-thenylidene (VM 26) (60 mg/m 2 for 2 days) and 1-(2-chloroethyl)-3-cyclohexyl-1-nitroso-urea (CCNU) (60 mg/m 2 for 2 days). These cycles of treatment were repeated as soon as the hematologic restoration was complete. The treatment was well-tolerated and the clinical condition of 31 out of 43 glioblastoma patients improved during the 2 months after the beginning of the treatment. Six out of eight patients with breast cancer metastases, one out of 13 with bronchial cancer metastases, and three out of nine with other types of cancer metastases also benefitted from the treatment. Examination of the results reveals the following characteristics: 1. A low degree of efficiency of this combination in the treatment of brain metastases, except for breast cancer metastases. 2. Absence of complete correlation between the clinical results observed and the cinegammagraphic developments 3. Similarity of the results independent of the initial localization 4. Establishment of a 6-month median survival period, with ten patients at present in a state of apparently complete remission, 180-506 days after beginning of the treatment.

Adult↗
PubMed1978

Adjuvant therapy of T1 bladder carcinoma: preliminary results of an EORTC randomized study.

This paper reports the preliminary results of an ongoing clinical trial in patients with category T1 bladder cancer who are randomized after transurethral resection to receive either thiotepa, VM-26, or no treatment. While there are no significant differences between the three treatment groups with respect to the time until first recurrence, thiotepa has significantly reduced the recurrence rate as compared to either VM-26 (P = 0.03) or no treatment (P = 0.04) among the 215 patients for whom follow-up information is currently available.

Humans↗
PubMed1980

The epipodophyllotoxin derivatives VM-26 and VP-16-213, 1976-1979, a review.

The epipodophyllotoxin derivatives VM 26 and VP 16-213 are currently entering phase III studies. The mechanism of their action is incompletely understood, but the greatest lethal effect is experienced in the late S and G2 phases. In transplanted tumors both drugs have shown marked schedule dependency and human studies also support this. As a single agent VP 16-213 is among the most active drugs in small-cell carcinoma of the lung. Significant clinical activity (> 20% response frequency) has been observed for both drugs in Hodgkin's disease, non-Hodgkin lymphomas and possibly in other more rare tumors (monocytic leukemia, hepatoma and teratoma). Although further clinical studies of both drugs would be ideal, it seems possible at present to justify a discontinuation of VM-26 in order to concentrate the efforts on VP 16-213. Further studies are needed to define optimal dose and schedule and place in combination chemotherapy.

Animals↗