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PubMed1994

Poor outcome of intensive chemotherapy for adult acute lymphoblastic leukemia: a possible dose effect.

Fifty consecutive adult patients with acute lymphoblastic leukemia (ALL) were treated with an intensive cyclical chemotherapy and the mean received dose of individual cytotoxic drug was retrospectively studied. The median age was 28 years. Twenty-one (43%) had white blood cell (WBC) count over 30 x 10(9)/l. Of the 26 patients with successful cytogenetic studies, ten (28%) had unfavorable clonal chromosomal abnormalities (four Philadelphia chromosome, six others). A high complete remission (CR) rate (86%) was achieved. This was associated with delivery of 100% of the planned dosage of vincristine, prednisone, and daunorubicin at induction. Dose reduction of asparaginase, the fourth drug in the induction protocol, was recorded in 20 (40%) patients. The CR rate of these patients was not adversely affected. Dose reduction was recorded during consolidation (38 of 43 remitters) and maintenance (18 of 20 remitters) as a result of treatment toxicity. The mean received dose of teniposide, Ara-C, asparaginase, mercaptopurine, and methotrexate was 73% (SD 7%), 73% (SD 7%), 62% (SD 41%), 65% (SD 15%) and 73% (SD 17%) of the planned dosage, respectively. The 5-year overall survival and leukemia-free survival (LFS) were 11% (95% CI: 0-27%) and 13% (95% CI: 0-26%), respectively. Even standard-risk patients had 4-year LFS of only 26% (95% CI: 0-57%). Among 36 remitters not withdrawn from consolidation, there were 29 treatment failures after a median follow-up of 42 months; 25 (86%) of these were leukemia relapse, three (10%) were toxic death during consolidation, and one patient (4%) died from therapy-related myelodysplastic syndrome. We postulate inadequate drug delivery during postremission therapy contributed to the high relapse rate in the whole group as well as the standard-risk patients.

Adult↗

PubMed1993

Clinical pharmacokinetics and pharmacodynamics of epipodophyllotoxins.

The disposition of epipodophyllotoxins is understood in considerable detail compared to other anti-cancer agents. Recent insights into the pharmacokinetic-pharmacodynamic relationship between etoposide and teniposide systemic exposure and both toxicity and outcome offer a basis for more rational approaches to drug dosage, with the emphasis on systemic exposure achieved, rather than the amount of drug administered per body surface area. Recent studies indicate that chronic--for example 21 days--administration of low dose etoposide may be a more effective dosage schedule for some malignancies. Until the longer term toxicities have been assessed, enthusiasm for this new dosage schedule must be tempered by the potential for greater risk of second malignancies, which has been associated with the frequent--weekly or twice weekly--administration of larger intravenous doses. Measurement of active intracellular drug (and metabolite) concentrations have identified correlations for toxicity and clinical efficacy for such drugs as methotrexate, 6-mercaptopurine, cytarabine and platinum complexes (Plunkett et al, 1985; Reed et al, 1987; Lennard and Lilleyman, 1989; Whitehead et al, 1990). Similar approaches are feasible for the epipodophyllotoxins and may provide an additional strategy for further improvement in the use of these active compounds.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1994

Quantitative and qualitative aspects of topoisomerase I and II alpha and beta in untreated and platinum/cyclophosphamide treated malignant ovarian tumors.

Quantitative and qualitative aspects of topoisomerase (Topo) I and II were studied in 17 malignant ovarian tumors [eight untreated and nine after platinum/cyclophosphamide (Pt/Cy) chemotherapy]. Median Topo II catalytic activity was lower (P < 0.05) in tumors after Pt/Cy chemotherapy in comparison to untreated tumors, while no differences were found for Topo I catalytic activity in tumors before and after chemotherapy, as was also found in a previous study (Van der Zee et al. Cancer Res., 51: 5915-5920, 1991). Teniposide (VM-26)-induced cleavable complex formation correlated (r = 0.60; P < 0.05) with Topo II activity, while Topo II decatenation activity was equally but incompletely inhibited by VM-26 in all tumors. No differences were found in Topo II cleavage site patterns in plasmid BR322 DNA for all tumors using an indirect end-labeling procedure. Cleavable complex formation of Topo I by camptothecin (Cpt) did not correlate with Topo I catalytic activity, while Topo I catalytic activity could equally and completely be inhibited by Cpt. By Western blotting, Topo II alpha protein expression was detected in four of eight untreated tumors and three of nine tumors after Pt/Cy chemotherapy, whereas in all tumors a M(r) 150,000 degradation product of Topo II beta was detected. Topo I protein was detected in all tumors at varying levels, but the protein levels did not correlate with Topo I catalytic activity or cleavable complex formation by Cpt. Our study shows that Topo I and II, isolated from human malignant tumors, can be stimulated by Cpt and VM-26, respectively, to induce DNA cleavage, which suggests that topoisomerases are real targets for chemotherapy in patients with ovarian cancer. From in vitro data from the literature it appears that the cleavable complex assay reflects both quantitative and qualitative changes as well as changes in the phosphorylation state of Topo I and II. In combination with the feasibility of the cleavable complex assay for Topo I and II in human malignant tumors, which was found in the present study, it appears that at present the determination of cleavable complex formation by tumors seems to be the most promising parameter of Topo I or II expression in human tumors to be related to response to Topo I- or II-targeted chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1993

Topoisomerase II as a target of VM-26 and 4'-(9-acridinylamino)methanesulfon-m-aniside in atypical multidrug resistant human small cell lung carcinoma cells.

The Adriamycin-resistant small cell lung carcinoma cell line, GLC4/ADR, showed large differences in cross-resistance to drugs such as Adriamycin, etoposide (VP-16), teniposide (VM-26), 4'-(9-acridinylamino)-methanesulfon-m-anisidide (m-AMSA), and mitoxantrone, which stimulate the formation of topoisomerase (Topo) II-DNA complexes. GLC4/ADR cells demonstrated a reduced Topo II activity and no detectable levels of the P-glycoprotein compared to the parental GLC4 cells (S. De Jong et al., Cancer Res., 50: 304-309, 1990). In the present study, the resistance to VM-26 (59.5-fold) and to m-AMSA (4-fold) of GLC4/ADR after a 1-h incubation was further analyzed. Using the K(+)-sodium dodecyl sulfate precipitation assay, a reduction in VM-26- and m-AMSA-induced cleavable complex formation was found in GLC4/ADR cells compared to GLC4 cells that was related to the degree of resistance to each drug. Cellular accumulation of the VM-26 analogues VP-16 was 3- to 8-fold less and the accumulation of m-AMSA 1- to 2-fold less in GLC4/ADR cells than in the parental cells. Following the removal of VM-26, the cleavable complexes in GLC4/ADR cells disappeared at least 2-fold faster than in GLC4 cells, while the efflux of VP-16 was also enhanced in the resistant cells. On the contrary, no differences in cleavable complex disappearance or drug efflux between these cell lines were observed with m-AMSA. Efflux of both drugs, however, occurred at a much higher rate than cleavable complex disappearance. Using isolated nuclei, a reduction in cleavable complexes in GLC4/ADR was still observed with VM-26 as well as m-AMSA compared to GLC4. The resistant nuclei and nuclear extracts showed a 3-fold decrease in M(r) 170,000 Topo II by immunoblotting. No differences in cleavable complex formation were found between nuclear extracts of both cell lines, when the Topo II activities were equalized. These findings suggest that the cross-resistance to m-AMSA is due to a decreased amount of Topo II and decreased drug accumulation, while in addition to these mechanisms an increased rate of cleavable complex disappearance is involved in the cross-resistance to VM-26 of the GLC4/ADR cell line.

Amsacrine↗

PubMed1993

Enhanced expression of the DNA topoisomerase II gene in response to heat shock stress in human epidermoid cancer KB cells.

Type II DNA topoisomerase breaks both DNA strands, and many anticancer agents including etoposide (VP-16) and teniposide (VM-26) have been developed by targeting topoisomerase II molecules. In this study we examined whether expression of the topoisomerase II gene is regulated in response to heat shock stress in human epidermoid cancer KB cells. Exposure of KB cells to 42 degrees C for 3 to 24 h permitted cell growth at a slightly reduced rate but still at an exponential rate, in comparison with that at 37 degrees C, whereas exposure to 45 degrees C for 15 to 120 min caused the almost complete cessation of exponential growth. There appeared 5-fold or higher increases in mRNA levels of both topoisomerase II and a heat shock protein, hsp-70, after exposure to 42 degrees C for 3 h, but only a slight, if any, increase in topoisomerase I mRNA. Nuclear run-on assays showed increased transcription of topoisomerase II and the hsp-70 gene after exposure to 42 degrees C. By contrast, KB cells induced a rapid and transient increase of topoisomerase II mRNA after exposure to 45 degrees C for 15 to 30 min, whereas the cellular level of hsp-70 mRNA was dramatically enhanced 60 min after exposure to 45 degrees C. The immunoblot assay also demonstrated increased expression of topoisomerase II in KB cells exposed to 42 degrees C. Decatenation activity of the nuclear extracts from KB cells was increased 1.5-fold by exposure to 42 degrees C, but there appeared no increase in topoisomerase I activity. Prior exposure of KB cells to 42 degrees C enhanced the cytotoxicity of VP-16, but not that of a topoisomerase I-targeting agent, a camptothecin analogue, CPT-11. However, exposure of KB cells to 42 degrees C after treatment with VP-16 did not enhance the cytotoxicity induced by the drug. The formation of cleavable DNA-topoisomerase II-VP-16 complexes was also greatly increased by prior exposure to 42 degrees C. Our present study proposes the hypothesis that the topoisomerase II gene might be one of the heat-shock-inducible genes and that hyperthermic anticancer therapy with topoisomerase II-targeting antitumor agents can be improved.

Camptothecin↗

PubMed1993

Treatment of late bone marrow relapse in children with acute lymphoblastic leukemia: a Pediatric Oncology Group study.

Children with acute lymphoblastic leukemia (ALL) who have completed 2.5 to 3 years of initial chemotherapy have an off-therapy relapse rate of approximately 20%. In an attempt to improve the survival of children with a late bone marrow (BM) relapse (ie, occurring greater than 6 months after cessation of primary therapy), the Pediatric Oncology Group designed a randomized study to compare the efficacy of doxorubicin/prednisone and cytarabine/teniposide in a multidrug retreatment chemotherapy program. Treatment consisted of remission reinduction with vincristine, prednisone, and doxorubicin, central nervous system prophylaxis with triple intrathecal chemotherapy, and continuation therapy (for 132 weeks) with alternating cycles of oral 6-mercaptopurine/methotrexate and intravenous vincristine/cyclophosphamide. Patients received intermittent courses of either prednisone/doxorubicin (regimen 1) or teniposide/cytarabine (regimen 2) during continuation therapy and a late intensification phase with either vincristine, prednisone, and doxorubicin (regimen 1) or teniposide and cytarabine (regimen 2). One hundred two of 105 evaluable patients (97%) achieved a second complete remission. Twenty-eight of 50 patients on regimen 1 have failed compared with 28 or 52 patients on regimen 2 (log-rank analysis, P = .68), indicating that this trial was inconclusive as to which treatment regimen was superior. The overall 4-year event-free survival for children with a late BM relapse was 37% +/- 6%. Age less than 10 years at initial diagnosis (P < or = .001), white blood cell count less than 5,000/microL at relapse (P = .036) and duration of first remission greater than 54 months (P = .039) were independently associated with a more favorable outcome. While the randomized trial was inconclusive, prolonged second complete remissions were secured in more than one-third of children with a late BM relapse of ALL. The prognostic factors identified may help select children with a late BM relapse who can be successfully retreated with chemotherapy alone.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1996

Functional expression of human topoisomerase II alpha in yeast: mutations at amino acids 450 or 803 of topoisomerase II alpha result in enzymes that can confer resistance to anti-topoisomerase II agents.

DNA topoisomerase II is the target of a variety of important antitumor agents, including etoposide, adriamycin, and amsacrine. We have constructed a system for analyzing the action of anti-topoisomerase II agents using the yeast Saccharomyces cerevisiae and have constructed vectors for expressing human topoisomerase II functionally in yeast. We have demonstrated that temperature-conditional yeast TOP2 mutants can be complemented by expression of wild-type human topoisomerase II alpha. Furthermore, expression of human topoisomerase II in yeast results in a quantitatively unique pattern of sensitivity to amsacrine. We also have constructed mutations in human TOP2 based on previously identified mutations from a human cell line selected for resistance to teniposide. Our experiments demonstrate that mutation of either arginine 450 or proline 803 of human topoisomerase II can result in an enzyme that has altered sensitivity to anti-topoisomerase II agents, and that a human enzyme carrying both mutations confers a higher level of drug resistance than enzymes carrying either single mutation.

Alleles↗

PubMed1996

Improved outcome in adult B-cell acute lymphoblastic leukemia.

A total of 68 adult patients with B-cell acute lymphoblastic leukemia (B-ALL) were treated in three consecutive adult multicenter ALL studies. The diagnosis of B-ALL was confirmed by L3 morphology and/or by surface immunoglobulin (Slg) expression with > 25% blast cell infiltration in the bone marrow (BM). They were characterized by male predominance (78%) and a median age of 34 years (15 to 65 y) with only 9% adolescents (15 to 20 y), but 28% elderly patients (50 to 65 y). The patients received either a conventional (N = 9) ALL treatment regimen (ALL study 01/81) or protocols adapted from childhood B-ALL with six short, intensive 5-day cycles, alternately A and B. In study B-NHL83 (N = 24) cycle A consisted of fractionated doses of cyclophosphamide 200 mg/m2 for 5 days, intermediate-dose methotrexate (IdM) 500 mg/m2 (24 hours), in addition to cytarabine (AraC), teniposide (VM26) and prednisone. Cycle B was similar except that AraC and VM26 were replaced by doxorubicin. Major changes in study B-NHL86 (N = 35) were replacement of cyclophosphamide by ifosphamide 800 mg/m2 for 5 days, an increase of IdM to high-dose, 1,500 mg/m2 (HdM) and the addition of vincristine. A cytoreductive pretreatment with cyclophosphamide 200 mg/m2, and prednisone 60 mg/m2, each for 5 days was recommended in study B-NHL83 for patients with high white blood cell (WBC) count (> 2,500/m2) or large tumor burden and was obligatory for all patients in study B-NHL86. Central nervous system (CNS) prophylaxis/treatment consisted of intrathecal methotrexate (MTX) therapy, later extended to the triple combination of MTX, AraC, and dexamethasone, and a CNS irradiation (24 Gy) after the second cycle. Compared with the ALL 01/81 study where all the patients died, results obtained with the pediatric protocols B-NHL83 and B-NHL86 were greatly improved. The complete remission (CR) rates increased from 44% to 63% and 74%, the probability of leukemia free survival (LFS) from 0% to 50% and 71% (P = .04), and the overall survival rates from 0% to 49% and 51% (P = .001). Toxicity, mostly hematotoxicity and mucositis, was severe but manageable. In both studies B-NHL83 and B-NHL86, almost all relapses occurred within 1 year. The time to relapse was different for BM, 92 days, and for isolated CNS and combined BM and CNS relapses, 190 days (P = .08). The overall CNS relapses changed from 50% to 57% and 17%, most probably attributable to the high-dose MTX and the triple intrathecal therapy. LFS in studies B-NHL83 and B-NHL86 was significantly influenced by the initial WBC count < or > 50,000/microL, LFS 71% versus 29% (P = .003) and hemoglobin value > or < 8 g/dL, LFS 67% versus 27% (P = .02). Initial CNS involvement had no adverse impact on the outcome. Elderly B-ALL patients (> 50 years) also benefited from this treatment with a CR rate of 56% and a LFS of 56%. It is concluded that this short intensive therapy with six cycles is effective in adult B-ALL. HdM and fractionated higher doses of cyclophosphamide or ifosphamide seem the two major components of treatment.

Adolescent↗

PubMed1995

Structural domains of plant nuclear DNA as a constitutive component of the topoisomerase II/DNA complex.

The treatment of agarose embedded plant nuclei by strong protein denaturants was demonstrated to result in discrete self-fragmentation of intact nuclear DNA. The set of resultant DNA cleavage products involves two main types of DNA fragments sized about 50-100 kb and 300-500 kb, being of the same type in various eukaryotic representatives. The pattern of ordered DNA fragmentation has been shown to be similar both in intact nuclei and in histone-depleted ones thus suggesting that the observed DNA fragments represent preexisting DNA structural domains, corresponding to the higher levels of chromatin folding. The topoisomerase II-specific poison teniposide (VM-26) has been shown to increase the ordered DNA cleavage while the conditions stimulating the topoisomerase II-mediated reverse reaction lead to the reassociation of the cleaved DNA domains. The data presented suggest that the nuclear DNA structural domains are involved in functioning of the topoisomerase II/DNA complex, the main property of which is its ability to mediate the cleavage/reassociation reactions.

Cell Nucleus↗

PubMed1996

Drug-specific sites of topoisomerase II DNA cleavage in Drosophila chromatin: heterogeneous localization and reversibility.

DNA cleavage stimulated by different topoisomerase II inhibitors shows in vitro a characteristic sequence specificity. Since chromatin structure and genome organization are expected to influence drug-enzyme interactions and repair of drug-induced DNA lesions, we investigated topoisomerase II DNA cleavage sites stimulated by teniposide (VM-26), 4-demethoxy-3'-deamino-3'-hydroxy-4'-epi-doxorubicin (dh-EPI, a doxorubicin derivative), 4'-(9-acridinylamino)-methanesulfon-m-anisidide, and amonafide in the histone gene locus and satellite III DNA of Drosophila cells with Southern blottings and genomic sequencing by primer extension. VM-26 stimulated cleavage in the satellite III DNA, whereas the other studied drugs did not. All four drugs stimulated cleavage in the histone gene cluster, but they yielded drug-specific cleavage intensity patterns. Cleavage sites by dh-EPI and VM-26 were sequenced in the histone H2A gene promoter and were shown to be distinct. DNA cleavage analysis in cloned DNA fragments with Drosophila topoisomerase II showed that drugs stimulated the same sites in vivo and in vitro. Strand cuts were in vivo staggered by 4 bases, and base sequences at major dh-EPI and VM-26 sites completely agreed with known in vitro drug sequence specificities. Moreover, DNA cleavage reverted faster in the satellite III than in the histone repeats. While stimulating similar levels of DNA breakage in bulk genomic DNA, dh-EPI and VM-26 markedly differed for cleavage extent and reversibility in specific chromatin loci. The results demonstrate a high heterogeneity in the localization, extent, and reversibility of drug-stimulated DNA cleavage in the chromatin of living cells.

Amsacrine↗

PubMed1996

Results of the phase II EORTC study comparing paclitaxel/cisplatin with teniposide/cisplatin in patients with non-small cell lung cancer. EORTC Lung Cancer Cooperative Group.

Toxicity and response rates are evaluated in a randomized phase II study comparing paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ)/cisplatin with teniposide/cisplatin in the treatment of non-small cell lung cancer to decide whether this study should continue as a phase III trial. A response was seen in 26% (10 of 38) of the patients receiving teniposide/cisplatin and in 40% (14 of 35) of those receiving paclitaxel/cisplatin. Overall, evidence of toxicity was more severe in the cisplatin/teniposide group, especially with regard to myelotoxicity. Grade 4 neutropenia was seen in 66% of patients receiving teniposide compared with 29% of those treated with paclitaxel/cisplatin. The study is to continue as a phase III trial, with 150 patients expected to participate in each treatment group.

Adult↗

PubMed1996

Drug sensitivity and sequence specificity of human recombinant DNA topoisomerases IIalpha (p170) and IIbeta (p180).

Effective anticancer agents, such as epipodophyllotoxins and anthracyclines, exert their antitumor activity through stabilization of cleavable topoisomerase II/DNA complexes, which may result in DNA breakage on detergent addition. Two isozymes (alpha and beta) of DNA topoisomerase II are present in human cells; however, their roles as drug targets have not been completely defined. We determined the in vitro isoenzyme sensitivities to VM-26 (teniposide) and 4-demethoxy-3'-deamino-3'-hydroxy-4'-epi-doxorubicin (an anthracycline analog) and established the sequence selectivity of isoenzyme-mediated DNA cleavage. Human topoisomerases IIalpha and IIbeta were purified from yeast cells overexpressing the corresponding plasmid-borne cDNA. Enzyme sensitivities to drugs were measured by a DNA cleavage assay using 32P-labeled simian virus 40 DNA fragments, and cleavage sites were mapped using agarose and sequencing gels. Both isozymes were sensitive to the studied poisons. They stimulated similar cleavage intensity patterns in agarose and sequencing gels; however, minor differences could be detected. The results showed that local base preferences for DNA cleavage without drugs were different at positions -2 and -1. On the other hand, sequence specificities of VM-26 and 4-demethoxy-3'-deamino-3'-hydroxy-4'-epi-doxorubicin were identical for both isozymes and corresponded to those of the native murine enzyme. The identical drug sequence specificities suggested that molecular interactions of the tested drugs in the ternary complex are likely similar between the two isozymes. The current findings indicate that both topoisomerase IIalpha and IIbeta may be in vivo targets of antitumor poisons.

Animals↗

PubMed1996

Double knockout of the MRP gene leads to increased drug sensitivity in vitro.

Overexpression of the multidrug resistance-associated protein (MRP) gene has been implicated in the resistance of tumor cell lines to a wide array of chemotherapeutic agents, but its normal physiological function(s) remains unknown. We have compared the sensitivity to chemotherapeutic drugs and toxins of wild-type W9.5 embryonic stem cells (ES) and of single and double MRP gene knockout cells derived therefrom. MRP expression was totally abrogated in the double knockout cell line and partially abrogated in the single knockout cell line. Reverse transcription-PCR analyses demonstrated that the MDR1, MDR2, and MDR3 genes were not expressed in either wild-type or MRP knock-out cells. The cytotoxic activities of etoposide, teniposide, vincristine, doxorubicin, daunorubicin, and sodium arsenite were significantly greater in double knockout cells than in parental wild-type ES cells; single knockout ES cells displayed an intermediate level of sensitivity. In contrast, no difference in sensitivity to colchicine and 1-beta-D-arabinofuranosylcytosine existed between the cell lines. Etoposide accumulation in double knockout ES cells was 2-fold higher than in wild-type ES cells. These findings indicate that baseline MRP expression has the capacity to exert a protective role against the toxicity of multiple chemotherapeutic agents and natural toxins.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed1997

Bcl-2 and Bcl-XL can differentially block chemotherapy-induced cell death.

Bcl-2 and its homologue Bcl-XL are expressed in a variety of tumors and their expression modulates the sensitivity of tumor cells to a wide spectrum of chemotherapeutic agents and gamma-irradiation. In the present report, we generated clones of FL5.12 lymphoid cells with similar levels of Bcl-2 and Bcl-XL using the Flag epitope to determine if these survival proteins could provide equivalent protection when challenged with chemotherapy or gamma-irradiation. Using four M-phase specific chemotherapeutic agents, Bcl-XL and Bcl-2 provided similar protection against vincristine and vinblastine whereas Bcl-XL afforded as much as 50% greater cell viability than Bcl-2 against etoposide and teniposide-induced cell death. In addition, Bcl-XL provided significantly greater cell viability than Bcl-2 against methotrexate, fluorouracil, and hydroxyurea, three S-phase specific agents. In apoptosis induced by gamma-irradiation and cisplatin, two antitumor treatments that are cell-cycle phase-nonspecific agents, both Bcl-XL and Bcl-2 conferred similar protection against gamma-irradiation, but Bcl-XL provided better protection than Bcl-2 against cisplatin. These results indicate that Bcl-XL and Bcl-2 confer a differential ability to protect against chemotherapy-induced cell death, which appears to be dependent on the molecular mechanism targeted by the drug rather than its cell-cycle phase specificity.

Animals↗

PubMed1995

Cyclic AMP-dependent protein kinase type I is involved in hypersensitivity of human breast cells to topoisomerase II inhibitors.

Topoisomerase II (Topo II) is an essential enzyme that catalyzes the breakage of double-strand DNA and is the target of several effective anticancer drugs, including the epipodophyllotoxins. The regulatory subunits of the cyclic AMP-dependent protein kinase are differentially expressed in normal and cancer cells. The RIalpha subunit is overexpressed in cells transformed by transforming growth factor-alpha (TGF-alpha) or Ha-ras oncogene. It has been shown that murine cells transformed by Ha-ras become hypersensitive to Topo II-targeting anticancer drugs. In this report we have tested whether any correlation exists between the expression of RIalpha protein and cellular sensitivity of Topo II-targeting drugs. Normal human breast MCF-10A cells and their derivatives overexpressing TGF-alpha, Ha-ras, or the different protein kinase subunits were treated with either Topo II inhibitors, such as etoposide, teniposide, or amsacrine, or with drugs which act independently of Topo II, such as bleomycin. Here we show that MCF-10A TGF-alpha and MCF-10A Ha-ras cells overexpress the RIalpha protein and become hypersensitive to epypodophyllotoxins and amsacrine but not to bleomycin. Direct introduction of the RIalpha gene into MCF-10A induces hypersensitivity to Topo II inhibitor drugs. In contrast, the overexpression of the other protein kinase subunits, RIIbeta or Calpha, does not modify the drug sensitivity of MCF-10A cells. No differences in the mRNA/protein content or in the activity of Topo II were found between hypersensitive cells and parental MCF-10A cells, suggesting that RIalpha may influence drug sensitivity via modulation of events downstream of the Topo II-DNA cleavable complex.

Amsacrine↗

PubMed1997

Results of a BFM-based protocol for the treatment of childhood B-non-Hodgkin's lymphoma and B-acute lymphoblastic leukemia in Argentina.

PURPOSE: To report the feasibility and results of a study based on the BFM-ALL. NHL/86 protocol for B-non-Hodgin's Lymphoma (NHL) and B-Acute Lymphoblastic Leukemia (B-ALL) in Argentina. Design. Prospective, single arm, non-randomized trial. PATIENTS AND METHODS: From August 1988 to December 1993, 87 consecutive patients with B-NHL/B-ALL were admitted and 82 were eligible. The therapy was stratified according to stage. All patients received a cytoreductive prephase with cyclophosphamide and prednisone. Those with stage I-II were treated with three 5-day blocks of combined intense chemotherapy including dexamethasone, cyclophosphamidie, ifosfamide, cytarabine, teniposide, doxorabicin, and 500 mg/m2 of methotrexate as a 24 hour continuous infusion. Stage III received 6 blocks and those with stage IV/B-ALL received 6 intensified blocks in which 2 g/m2 of 24 hour continuous infusion methotrexate and vincristine were added. Triple intrathecal therapy was given for CNS prevention. After the first two blocks the response was assessed and those with a partial response were offered optionallya second look surgery or local radiotherapy. RESULTS: With a median follow-up of 38 (range 16-71) months, the event-free survival (pEFS) for the whole group was 0.69 (Stage I-II n = 16 pEFS = 0.94, stage III n = 50 pEFS = 0.66, Stage IV n = 7 pEFS = 0.43, B-ALL n = 9 pEFS = 0.66). Patients with stage III abdominal tumors who achieved a partial response by imaging studies after induction had a significantly higher risk of relapse than those with a complete response (p = 0.02). Relapse was the most frequent event Toxicity was mainly hematological. CONCLUSIONS: The application of this protocol was feasible in our setting and its results comparable to the German study. Patients with stage I-II had an excellent outcome. Those with stage III and B-ALL achieved an encouraging event-free survival, however those with abdominal tumors and partial response to induction chemotherapy fared less favourably. This strategy was less effective for patients with initial CNS disease.

Adolescent↗

PubMed1999

Improved outcome for acute lymphoblastic leukemia in children of a developing country: results of the Chilean National Trial PINDA 87.

BACKGROUND: The National Chilean Pediatric Oncology Group, PINDA, reports the first prospective, nonrandomized trial for acute lymphoblastic leukemia (ALL), using a modified version of the Berlin-Frankfurt-Munster protocol (ALL BFM 86). The aim of this study was to classify immunophenotypes, to decrease cranial irradiation, and to assess whether this protocol would improve the survival rate. PROCEDURE: From June, 1987, to June, 1992, 444 unselected children were diagnosed with ALL. Of them, 425 were evaluable. Therapy was stratified by risk. Standard-risk (SR) and high-risk (HR) patients received protocols I, M, II, and maintenance therapy. Very-high-risk (VHR) patients received protocol E instead of protocol M. All patients received a prephase treatment consisting of prednisone and intrathecal methotrexate (MTX). HR and VHR patients received cranial irradiation (12-18 Gy). The following changes were made to the ALL BFM 86 protocol: in protocol M, MTX 1 g/m2 instead of 5 g/m2; in protocol E, citarabine 1 g/m2 instead of 2 g/m2; mithoxantrone and ifosfamide were substituted by teniposide and cyclophosphamide. RESULTS: Immunophenotypes: pro-B-ALL, 14%; common ALL, 67.4%; pre-B-ALL, 4.3%; T-ALL, 10%; undifferentiated leukemia (AUL), 4.3%. The overall 5-year event-free survival (EFS) rate was 60% +/- 2% (SE). The 5-year EFS rate for each risk group was: SR 75%, HR 62%, VHR 28%, with a median follow-up of 6.5 years (range 4.5-9.5 years). The cumulative incidence of central nervous system (CNS) relapse was 5.4%. CONCLUSIONS: We have been able successfully to perform a nationwide study. Our strategy to adapt the BFM protocol to our population of patients trial was effective in improving the EFS. The immunophenotype distribution is similar to that in other reported series.

Adolescent↗

PubMed1997

Decreased drug accumulation in a mitoxantrone-resistant gastric carcinoma cell line in the absence of P-glycoprotein.

An established gastric-carcinoma cell line, EPG85-257P, is extremely sensitive to mitoxantrone (IC50, 0.12 ng/ml). Stepwise selection with mitoxantrone for 3 years resulted in a cell line (EPG85-257RN) that is 7,056-fold resistant to mitoxantrone (IC50, 846 ng/ml) and displays cross-resistance to the topoisomerase(topo)-II poisons ametantrone (411x), etoposide (112x) and teniposide (60x) as well as the topo-I poisons 7-ethyl-10-hydroxycamptothecin (331x) and topotecan (58x). We now show that this resistance is multifactorial. Western blotting revealed a 5-fold decrease in topo-IIalpha polypeptide in the mitoxantrone-resistant cells. Immunohistochemistry and Western blotting failed to demonstrate P-glycoprotein overexpression. Formation of trapped topo-II-DNA complexes in the resistant cells required higher mitoxantrone concentrations than in parental cells, even though nuclei isolated from the EPG85-257RN cells formed cleavage complexes normally. In agreement with these observations, which suggest the possibility of a defect in mitoxantrone accumulation, examination of mitoxantrone accumulation in both cell lines by confocal laser microscopy revealed that the EPG85-257RN cells accumulate less mitoxantrone at steady state. From these results, we propose that mitoxantrone accumulation, along with alterations in topo-IIalpha expression, contribute to the resistance to mitoxantrone observed in these cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗