Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0598934 (tumor growth)
 58,965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Synergy, when it can be convincingly established, is an effective strategy for the development of novel drug combinations. We have evaluated the interaction between 2'-deoxy-5-azacytidine (DAC) and 9-dimethylaminomethyl-10-hydroxycamptothecin (topotecan) based on our hypothesis that DAC, through DNA hypomethylation, might increase the transcription of topoisomerase I (topo I) leading to increased sensitivity to topotecan. Five human tumor cell lines, A375 melanoma, DX-3 melanoma, DMS4C non-small cell lung carcinoma, UP-1 unknown primary adenocarcinoma, SN12C renal carcinoma, and the murine CT-26 tumor cell line, were studied. Drug interactions were assessed using the multiple drug effect analysis of Chou and Talalay (Chors, T-C, and Talalay, P. Adv. Enzyme Regul., 22:27-54, 1984.). A synergistic interaction was documented in four human cell lines and the murine CT-26 line. An antagonistic interaction was observed with the SN12C cell line. The toxicology and efficacy of this combination were analyzed using CT-26 in BALB/c mice. Various treatment schedules were studied, including: single doses of each agent; single sequential combination treatments where DAC was administered followed by topotecan 24 h later; and multiple sequential treatments where DAC and topotecan were administered on days 1, 2, 8, and 9. Efficacy studies showed that the single sequential combination of DAC (50 mg/kg) and topotecan (10 mg/kg) resulted in tumor growth delay as compared to single doses of DAC (50 mg/kg) or topotecan (10 mg/kg). When the multiple sequential combination schedule was used, the antitumor effect was more pronounced. In that experiment 50% of the control animals had tumors of 20 mm by day 28. For animals receiving a single sequential treatment with DAC and topotecan, the median time until the mean tumor size reached 20 mm was 38 days, and for the group with multiple sequential combination treatments the time was 51 days. Studies of the mechanism of the interaction showed that the activity of topotecan versus each cell line correlated with the topo I activity in nuclear extracts However, there was no correlation between topo I levels and synergy and no reproducible increase in topo I activity following exposure to DAC. Thus, while the exact mechanism of the interaction remains unclear, DAC can be effectively combined with topotecan to enhance antitumor activity.
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PMID:Synergistic cytotoxicity with 2'-deoxy-5-azacytidine and topotecan in vitro and in vivo. 137 5

Topoisomerase I inhibition detected in mammalian cells can be correlated with reduced tumor growth. Camptothecin specifically inhibits topoisomerase I by stabilization of a covalently linked DNA-enzyme complex and associated DNA single-strand breaks. Whether perturbations in nuclear DNA structure can alter camptothecin-induced DNA damage was examined using the non-intercalative DNA minor groove binders distamycin, Hoechst 33258 and DAPI (4',6-diamidino-2-phenylindole). L1210 nuclei were treated with camptothecin alone or in the presence of single minor groove binders. DNA-protein crosslinks and single-strand breaks were determined using potassium-sodium dodecyl sulfate precipitation and alkaline elution respectively. Distamycin produced a dose-dependent decrease in DNA-protein crosslinks and strand breaks. This effect was reduced if nuclei were treated with camptothecin prior to distamycin addition. Distamycin was unable to reverse lesions once induced or to prevent repair of damage upon camptothecin removal. Hoechst 33258 and DAPI also decreased camptothecin-induced DNA damage. The order of inhibitory potency was: distamycin greater than Hoechst greater than DAPI. This order corresponded to the molecular weights as well as to the size of the nucleotide binding sites of the drugs. Identifying agents which alter such DNA lesions should provide better understanding of the chemotherapeutic activity of camptothecin as well as help elucidate new leads for drug combinations of improved therapeutic benefit.
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PMID:Effects of minor groove binding drugs on camptothecin-induced DNA lesions in L1210 nuclei. 168 78

A series of analogs based on a novel template, 11-aza-(20S)-camptothecin, were obtained from total synthesis and tested as potential anticancer drugs in the topoisomerase I enzyme cleavable complex assay. The parent compound 11-aza-(20S)-camptothecin (8) was derived from a Friedlander condensation between the known aminopyridine derivative 3-(3-amino-4-picolylidene)-p-toluidine and optically active tricyclic ketone 7. Compound 8 had activity approximately twice that of (20S)-camptothecin in the calf thymus topoisomerase I cleavable complex assay. Compounds were prepared wherein the 11-aza nitrogen atom was quaternized as either the corresponding N-oxide or methyl iodide. Compounds with quaternized N-11 showed improved water solubility and were equipotent to the clinically investigated camptothecin analog topotecan in the cleavable complex assay. These compounds were evaluated in vivo in nude mice bearing HT-29 human colon carcinoma xenografts. The analog 11-aza-(20S)-camptothecin 11-N-oxide was found to significantly retard tumor growth when compared to untreated controls. Finally, 7,10-disubstituted 11-azacamptothecin analogs were synthesized using Pd(0) coupling reactions of 10-bromo-7-alkyl-11-aza-(20S)-camptothecins 19 and 20, which in turn were available from a Friedlander condensation of the novel bromopyridine derivatives 17a and 17b with 7. Among the 10-substituted series, a number of analogs displayed extremely high in vitro potency against topoisomerase I and improved aqueous solubility. A significant number of the compounds were found to be active in whole cell cytotoxicity assays and several were evaluated in nude mice bearing the HT-29 tumor xenografts. The most effective of these proved to be (S)-11-aza-7-ethyl-10-(aminohydroximinomethyl)camptothecin trifluoracetic acid salt (27), a potent topoisomerase I inhibitor which demonstrated excellent efficacy in both short term and in extended in vivo assays. A comparison between in vitro enzyme data and in vivo data from nude mouse studies in other compounds in this series revealed a poor overall correlation between topoisomerase inhibition in vitro and antitumor efficacy in vivo.
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PMID:Synthesis, topoisomerase I inhibitory activity, and in vivo evaluation of 11-azacamptothecin analogs. 770 14

Topoisomerase I and topoisomerase II allow a metabolically active cell to mobilize its supercoiled chromosomal DNA and undergo replication, transcription, recombination, and repair. Several topoisomerase inhibitors have recently been shown to be active in preclinical systems. Topotecan (SK&F 104,864), a water-soluble camptothecin analog, is an inhibitor of topoisomerase I. Novobiocin is an inhibitor of topoisomerase II. Lonidamine depletes cellular adenosine 5'-triphosphate (ATP) and may impede energy-dependent DNA repair, MCF-7 human breast-cancer cells were treated in vitro with topotecan, novobiocin, and lonidamine alone, in paired combinations, and in combination with CDDP and melphalan. The three enzyme inhibitors alone and in combination did not increase tumor cell sensitivity to CDDP. However, the combinations of topotecan/novobiocin and lonidamine/novobiocin did enhance the cytotoxicity of melphalan. Mice bearing the FSaII fibrosarcoma were treated in vivo with topotecan, novobiocin, and lonidamine alone, in paired combinations, and in combination with CDDP, melphalan, BCNU, and cyclophosphamide. The combination of topotecan/novobiocin had the greatest impact on tumor cell sensitivity to each cytotoxic agent tested in both tumor cell-survival and tumor growth-delay assays. This sensitization was greatest at the highest concentrations of the cytotoxic agent tested. Combinations of topoisomerase I and topoisomerase II inhibitors may be useful as modulators of antitumor alkylating agents.
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PMID:Modulation of antitumor alkylating agents by novobiocin, topotecan, and lonidamine. 825 94

The cytotoxicity of the topoisomerase I inhibitors, camptothecin and topotecan, toward exponentially growing EMT-6 murine mammary carcinoma cells under various conditions of oxygenation, pH and temperature was assessed. Under normal pH (pH 7.40) conditions both camptothecin and topotecan were more cytotoxic toward normally oxygenated cells. Both agents were more cytotoxic under acidic pH (pH 6.45) and the differential in cytotoxicity due to the cellular oxygenation level disappeared. Neither camptothecin nor topotecan was enhanced in cytotoxicity by hyperthermia (42 degrees C or 43 degrees C, 60 min) during drug exposure. Both camptothecin and topotecan killed increasing numbers of FSaIIC tumor cells with increasing dose of the drugs in vivo in a log/linear manner. Local hyperthermia (43 degrees C, 30 min) increased the tumor cell killing of the drugs but decreased the toxicity of these agents to the bone marrow granulocyte/macrophage-colony-forming units. Topotecan was a more effective modulator of cisplatin than was camptothecin, as determined by FSaIIC tumor cell survival assay and by FSaIIC tumor growth delay. Although both camptothecin and topotecan were effective additions to a treatment regimen including cisplatin and daily fractionated radiation (5 x 3Gy), neither of these topoisomerase I inhibitors increased the tumor growth delay produced by the trimodality regimen of cisplatin/hyperthermia/radiation.
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PMID:Addition of a topoisomerase I inhibitor to trimodality therapy [cis-diamminedichloroplatinum(II)/heat/radiation] in a murine tumor. 839 65

The efficacy of the topoisomerase I inhibitor CPT-11 [7-ethyl-10-(4-[1-piperidino]-1-piperidino)-carbonyloxycamptothec in] has been evaluated against a panel of human tumor xenografts derived from adult and pediatric malignancies. Tumors included eight colon adenocarcinomas representing intrinsically chemorefractory malignancies, six lines derived from childhood rhabdomyosarcoma (three embryonal and three alveolar) representing a chemoresponsive histiotype, and sublines of rhabdomyosarcomas selected in vivo for resistance to vincristine, melphalan, and the topoisomerase I inhibitor 9-dimethylaminomethyl-10-hydroxycamptothecin (topotecan). CPT-11 was given by i.v. administration daily for 5 days each week for 2 weeks (one cycle of therapy) or on the same schedule with cycles repeated every 21 days. The maximum tolerated dose for a single cycle of treatment was 40 mg/kg/dose, and for 3 cycles the maximum tolerated dose was 10 mg/kg/dose. Treatment was started against advanced tumors. Against colon adenocarcinomas CPT-11 administered for one cycle at the maximum tolerated dose caused complete or partial regression (> or = 50% reduction in tumor volume) in 5 of 8 lines. One cycle of CPT-11 therapy caused significant inhibition of tumor growth, without 50% regression, in 2 of 3 other colon adenocarcinomas. Rhabdomyosarcoma xenografts derived from untreated patients were highly responsive to CPT-11, which caused complete regression in 5 of 6 lines even at 20 or 10 mg/kg/dose. CPT-11 retained complete activity against rhabdomyosarcomas selected for resistance to vincristine and caused complete regressions in a line selected for resistance to melphalan that was also completely cross-resistant to topotecan. Of note was the observation that CPT-11 was as active against two xenografts selected for primary resistance to topotecan as it was against the respective parental tumors. Preliminary data indicate that CPT-11, like the topoisomerase I inhibitor topotecan, may have increased therapeutic efficacy when administered at a low dose for protracted periods (3 cycles). A comparison of the efficacy of CPT-11 with topotecan is presented.
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PMID:Therapeutic efficacy of the topoisomerase I inhibitor 7-ethyl-10-(4-[1-piperidino]-1-piperidino)-carbonyloxy-camptothecin against human tumor xenografts: lack of cross-resistance in vivo in tumors with acquired resistance to the topoisomerase I inhibitor 9-dimethylaminomethyl-10-hydroxycamptothecin. 850 25

Soft tissue sarcomas account for approximately 1% of all malignancies. They constitute a wide range of different tumor types with very different clinical courses and treatment sensitivities. Our understanding of the molecular mechanisms of tumor growth in sarcomas is increasing rapidly. These new data will probably lead to drastic changes in our current classification systems, which are primarily based on routine microscopy. This might also bring about a more detailed and reliable prognostic evaluation in individual tumors. Hopefully, this knowledge will guide us towards a more rational and more successful development of new therapies. Current surgical approaches and treatment protocols are more or less well defined. Knowledge on when to use ionizing radiation for local control is reasonably clear. Major difficulties however remain for both these treatment modalities in cases of both truncal and retroperitoneal sarcomas. The lack of new very active chemotherapeutic agents against this group of diseases has remained unchanged in the past years, although both the taxanes and the topoisomerase I inhibitors show some activity.
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PMID:Diagnosis and treatment of soft tissue sarcomas in adults. 886 3

9-Amino-20(S)-camptothecin (9-AC) has demonstrated efficacy against several human cancer xenografts, including cancers of the colon, breast, lung, ovary, and stomach and malignant melanoma, and is currently undergoing Phase I clinical trials. In vitro data indicate that the addition of topoisomerase I inhibitors shortly after irradiation causes conversion of single-strand breaks to double-strand breaks, resulting in synergistic lethality to cultured log-phase or quiescent malignant cells. In our study, the efficacy of 9-AC as a potential radiosensitizing agent in vivo was assessed in C3Hf/Kam female mice bearing 7.6-8-mm MCa-4 mammary tumors implanted i.m. into the right posterior thigh. In one series of experiments to determine the dose dependence of 9-AC, mice were injected twice a week with either 0.5, 1.0, or 2.0 mg/kg 9-AC (total doses of 2, 4, and 8 mg/kg, respectively) either alone or 1 h before irradiation. In a second series of experiments, the schedule dependence of 9-AC was determined by giving a constant total dose of 4 mg/kg 9-AC once (2 mg/kg), twice (1 mg/kg every third day), or four (0.5 mg/kg every other day) times per week for 2 weeks, either alone or combined with radiation. The same radiation regimen was used in all experiments: 2-Gy fractions daily for 14 consecutive days, giving a total dose of 28 Gy to the tumor-bearing leg only. Tumor response was assessed by regrowth delay and dose modification factors (DMFs) obtained by comparing regrowth delay in the groups given 9-AC alone with those given the same dose of 9-AC and radiation. 9-AC significantly delayed tumor growth when combined with radiation, and this effect was dependent on drug dose; DMFs of 2.4 [95% confidence interval (CI), 2.0-3.1], 3.7 (95% CI, 3.1-4.6), and 3.3 (95% CI, 2.7-4.1) were obtained for groups treated with total drug doses of 2.0, 4.0, and 8.0 mg/kg 9-AC, respectively. In addition, the same total dose of 4 mg/kg 9-AC was more effective when given either twice or four times a week compared with once a week, giving DMFs of 2.8 (95% CI, 2.2-3.9), 2.6 (95% CI, 2.0-3.6), and 1.7 (95% CI, 1.3-2.4), respectively. The effect of 9-AC and radiation on normal tissue toxicity was assessed in two normal tissues, jejunum and skin, in separate groups of mice. Jejunal crypt cell survival was decreased in those mice given single doses of 9-AC ranging from 0.5-4.0 mg/kg and 12.5 Gy of total body radiation compared with those given 12.5 Gy of total body irradiation alone. The same regimen of drug and radiation did not modify acute skin reactions. These results suggest that 9-AC is an effective in vivo radiosensitizing agent when given in divided doses with fractionated irradiation. In addition, the gastrointestinal tract but not skin could be a critical target tissue for the use of 9-AC combined with radiation.
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PMID:Potentiation of murine MCa-4 carcinoma radioresponse by 9-amino-20(S)-camptothecin. 915 87

9-Aminocamptothecin (9-AC) is a topoisomerase I inhibitor currently being developed as an antineoplastic agent. The aim of these preclinical studies was to assess the activity of 9-AC against prostate cancer, a malignancy notoriously insensitive to most cytotoxic agents in the clinic. The activity of 9-AC was first tested in vitro against one hormone-sensitive (LNCaP) and three hormone-resistant (PC-3, PC-3M, and DU145) human prostate cancer cell lines. After 96 h of drug exposure, concentrations required to inhibit cell viability to 50% of control values (IC50s) were 34.1, 10, 6.5, and 8.9 nm for PC-3, PC-3M, DU145, and LNCaP, respectively. Because 9-AC is known to undergo rapid hydrolysis, we assayed lactone levels in tissue culture medium over 24 h and found that the half-life was 20 min, with only 15%of the drug remaining as lactone at steady state. Consequently, the IC50s calculated from a single dose of the drug may represent overestimates. Subsequently, we tested the activity of a colloidal dispersion formulation of 9-AC against PC-3 implanted into flanks of nude mice. 9-AC was given for a total of 3 weeks by daily oral gavage (excluding weekends) or by twice weekly s.c. injections. 9-AC inhibited tumor growth at the lowest oral dose (0.35 mg/kg/day), whereas higher oral doses (0.75 and 1 mg/kg/day) and s.c. administration (4 mg/kg/week) caused tumor regression. 9-AC was well tolerated at all doses, with no toxic death or weight loss of more than 10% observed in any group. Finally, we considered that the activity of 9-AC seen in the mouse xenograft model might be explained, in part, by the relatively acidic tumor microenvironment, which would favor the formation of the more potent lactone. Simultaneous determination of plasma and tumor 9-AC lactone concentrations confirmed this hypothesis. Taken together, these studies suggest that 9-AC should be submitted for clinical trials in patients with prostate cancer.
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PMID:9-Aminocamptothecin: a topoisomerase I inhibitor with preclinical activity in prostate cancer. 981 85

The topoisomerase I inhibitor GL147211C [7-[(4-methylpiperazino)methyl]-10,11-(ethylenedioxy)-(20S)-campto thecin trifluoroacetate], a camptothecin analogue, has significant activity in tumor cell cytotoxicity assays in vitro and antitumor activity in both animal tumor models and human patients. Its toxicity is significant, however, effectively limiting the amount of drug that can be administered and its clinical utility. To determine whether the therapeutic index of GL147211C could be improved, the drug was encapsulated in long-circulating, pegylated (STEALTH) liposomes (SPI-355). The pharmacokinetics and antitumor activity of SPI-355 were compared to those of nonliposomal GL147211C. The plasma pharmacokinetics of SPI-355 in rats were typical of those of other pegylated liposomal formulations, with significantly increased blood circulation time; the dose-corrected area under the curve and Cmax of SPI-355 (10 mg/kg) were 1250- and 35-fold higher, respectively, than those of nonliposomal GL14711C (8.72 mg/kg). The comparative antitumor activity of SPI-355 and nonliposomal GL1472211C was evaluated in nude mice implanted with HT29 colon carcinoma xenografts. SPI-355 was 20-fold more effective than GL147211C in inhibiting tumor growth (1 mg/kg SPI-355 and 20 mg/kg GL147211C) and produced durable complete remissions of tumors at well-tolerated dose levels that were >5-fold lower than the maximally tolerated dose of GL147211C, which induced no durable complete responses. Signs of toxicity were similar between the two drugs, but liposome encapsulation increased the toxicity of drug approximately 4-fold, with increased weight loss and several deaths with SPI-355 (5 mg/kg SPI-355 versus 20 mg/kg GL147211C). Despite the increased toxicity seen with SPI-355, the therapeutic index of the liposomal formulation was increased approximately 5-fold over that of nonliposomal GL147211C, suggesting that such a pegylated liposomal formulation could demonstrate increased therapeutic index in human patients.
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PMID:Encapsulation of the topoisomerase I inhibitor GL147211C in pegylated (STEALTH) liposomes: pharmacokinetics and antitumor activity in HT29 colon tumor xenografts. 986 23


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