In vitro and in vivo activities of syn2836, syn2869, syn2903, and syn2921: new series of triazole antifungal agents.

The in vitro and in vivo activities of four azole compounds belonging to a new series of 2(2,4-difluorophenyl)-3-(4-substituted piperazin-1-yl)-1-(1,2,4-triazol-1-yl) butanol antifungal agents is described. The compounds were selected from a library of azole compounds synthesized by our group. The in vitro activities of Syn2869, Syn2836, Syn2903, and Syn2921 against a panel of over 240 recently collected clinical isolates of yeast and molds were determined, and the results were compared with those obtained with fluconazole (FLC), itraconazole (ITC), and amphotericin B (AMB). The MICs at which 90% of the isolates were inhibited (MIC(90)s) for the four test compounds for strains of Candida spp. ranged from <0.048 to 0.78 microg/ml. All compounds were also active against FLC-resistant Candida albicans and other Candida sp. strains. Moreover, MIC(90)s for strains of Cryptococcus neoformans, Aspergillus spp., Trichophyton spp., and Microsporum spp. were also low and ranged from <0.048 to 0.39 microg/ml. The test compounds produced a fungistatic pattern during the time-kill kinetic studies. In vivo studies indicated that all four test compounds have good efficacies against C. albicans in a murine systemic infection model and significantly improved the survival rates of the infected mice. The results for Syn2903 were similar to those for FLC, while the other compounds were slightly less effective but had ranges of activities similar to the range of activity of ITC. The compounds were also evaluated against an Aspergillus fumigatus systemic infection. Syn2903 was also superior to ITC, whereas the efficacy data for the other compounds were similar to those for ITC. It was concluded from the data generated for this new series of azole compounds in the studies described above that further pharmacokinetic and toxicologic evaluations are warranted prior to selection of a candidate compound for preclinical testing.

Experimental postoperative adjuvant chemotherapy by UFT using primary tumor amputation model.

We evaluated the postoperative adjuvant chemotherapy by UFT using the primary tumor amputation-pulmonary metastasis model. When Lewis lung carcinoma (LLC) primary tumors on the hind foot pad grew palpable, they were amputated on two different days. In experiment (A) (earlier amputation model), micrometastases were detected on the day of amputation only by the histopathological examination. In the experiment (B) (later amputation model), nodules could be determined even by necropsy. Long-term (60-day) consecutive administration of UFT (22 mg/kg/day), which produced no body weight loss, markedly prolonged the survival period in experiment (A) (ILS: over 118%), 1 of the 15 mice being cured. UFT had a relatively weak but significant effect (67% of ILS) in schedule (B). Using the same model, we examined the inhibitory effect of UFT (2-week administration) on the number of metastatic nodules. A significant decrease of metastatic nodules was observed by UFT with both amputation schedules, but its effect was superior with schedule (A). In the same model using Colon 26 PMF-15, UFT markedly prolonged the survival period of mice (150% of ILS) and significantly decreased the metastatic nodules (86% inhibition). The dose of UFT used was relatively low, and did not significantly inhibit the growth of large tumors. However, the sensitivity to the micrometastases was high. These findings suggest that the postoperative adjuvant chemotherapy by the long-term consecutive administration of UFT would be effective for clinical cancer especially in curatively resected cases.

In vitro and in vivo activities of Syn2190, a novel beta-lactamase inhibitor.

Syn2190, a monobactam derivative containing 1,5-dihydroxy-4-pyridone as the C-3 side chain, is a potent inhibitor of group 1 beta-lactamase. The concentrations of inhibitor needed to reduce the initial rate of hydrolysis of substrate by 50% for Syn2190 against these enzymes were in the range of 0.002 to 0.01 microM. These values were 220- to 850-fold lower than those of tazobactam. Syn2190 showed in vitro synergy with ceftazidime and cefpirome. This synergy was dependent on the concentration of the inhibitor against group 1 beta-lactamase-producing strains, such as Pseudomonas aeruginosa, Enterobacter cloacae, Citrobacter freundii, and Morganella morganii. However, against beta-lactamase-derepressed mutants of P. aeruginosa, the MICs of ceftazidime plus Syn2190 were not affected by the amount of beta-lactamase, and the values were the same for the parent strains. The MICs at which 50% of isolates are inhibited (MIC(50)s) of ceftazidime plus Syn2190 were 2- to 16-fold lower than those of ceftazidime alone for ceftazidime-resistant, clinically isolated gram-negative bacteria. Similarly, the MIC(50)s of cefpirome plus Syn2190 were two- to eightfold lower for cefpirome-resistant clinical isolates. The synergies of Syn2190 plus ceftazidime or cefpirome observed in vitro were also reflected in vivo. Syn2190 improved the efficacies of both cephalosporins in both a murine systemic infection model with cephalosporin-resistant rods and urinary tract infection models with cephalosporin-resistant P. aeruginosa.

MJ347-81F4 A & B, novel antibiotics from Amycolatopsis sp.: taxonomic characteristics, fermentation, and antimicrobial activity.

Strain MJ347-81F4 has been found to produce two new cyclic thiazolyl peptide antibiotics, components A and B. Taxonomic studies including morphological and physiological characteristics and chemical analysis of whole cells of the producing strain revealed this microorganism to belong to genus Amycolatopsis, and so we designated the strain Amycolatopsis sp. MJ347-81F4. After 10 to 12 days of fermentation, most of the antibacterial activity was present mainly in the mycelial cake and reached its maximum level. In comparison with reference compounds, A as the major component showed excellent in vitro activity against gram-positive bacteria including highly methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecalis with MICs in the range of concentration of 0.006 to to approximately 0.1 microg/ml. The results on the antimicrobial activity against thiazolyl peptide-resistant mutants of Bacillus subtilis NRRL B-558 indicated that the possible molecular target of MJ347-81F4 component A might be the 50S subunits of the ribosome, the inactivation of which would inhibit protein synthesis.

[Development of beta-lactamase inhibitors].

The proportion of beta-lactamase producing bacteria in each species of clinical isolates is high (over 90%) in these years. According to the survey of bacterial resistance in 1995, higher proportion of resistant bacterial species against ampicillin, piperacillin (PIPC), cefazolin, cefotiam was observed. To overcome the bacterial resistance against these beta-lactam antibiotics, we have made a development of beta-lactamase inhibitor and its combination antibiotic. New beta-lactamase inhibitor, tazobactam (TAZ) showed strong inhibitory activity against various kinds of beta-lactamases including cephalosporinases. The combination antibiotic, TAZ/PIPC(TAZ combined with PIPC by 1 to 4) showed stronger antibacterial activity than PIPC against beta-lactamase producing stains. And also the activity of TAZ/PIPC was superior to PIPC in the mixed bacterial infection model in mouse. The in vitro and in vivo frequency of emergence of resistant bacteria from Enterobacteriacae treated with TAZ/PIPC was lower than that of PIPC or ceftazidime (CAZ). By these data, combined antibiotics with beta-lactamase inhibitor was effective to resolve the problems of bacterial resistances caused by beta-lactamases.

Postsurgical oral administration of uracil and tegafur inhibits progression of micrometastasis of human breast cancer cells in nude mice.

We recently established a metastasis model in nude mice using the MKL-4 cell line, a contransfectant of the MCF-7 human breast cancer cell line with fgf-4 and lacZ in which micrometastases in several organs can be quantitatively observed. First, to develop a new postsurgical metastasis model, we investigated the timing of occurrence of micrometastasis and the influence of tumor removal on the progression of micrometastasis in this model. Micrometastases into lymph nodes and lungs were detected 3 weeks after the cell injections. Tumor removal 3 weeks after the injections significantly enhanced the progression of micrometastasis into lymph nodes and bone. Second, to study the effect of a mixed compound, UFT (a molar ratio of uracil:tegafur of 4:1), which has been widely used in the postsurgical adjuvant setting in Japan, 15 or 20 mg/kg UFT were administered p.o. for 4 weeks to tumor-bearing mice or to mice in which transplanted tumors were resected 3 weeks after the injections. Either dose of UFT significantly inhibited the tumor growth as well as the progression of micrometastasis into lymph nodes, lungs, liver, and brain. In addition, enhanced progression of micrometastasis in all explored organs by the tumor removal was significantly inhibited by the administration of either dose of UFT. In conclusion, this new postsurgical metastasis model may be useful for evaluating the efficacy of agents used in the postoperative adjuvant setting. UFT may be an effective drug for inhibiting the progression of micrometastasis after surgery.

Augmentation of the chemotherapeutic effectiveness of UFT, a combination of tegafur [1-(2-tetrahydrofuryl)-5-fluorouracil] with uracil, by oral l-leucovorin.

UFT, combination of tegafur [1-(2-tetrahydrofuryl)-5-fluorouracil] with uracil, is widely-used as an anti-neoplastic agent in Japan. We evaluated the anti-tumor efficacy of the combined modality of UFT with oral l-leucovorin. The augmentation of anti-tumor activity of UFT by co-administration of l-leucovorin was observed over a dose of 1.85 mg/kg (5.55 mg/m2) and was significant at a dose of 5.56 mg/kg (16.7 mg/m2). Using ten human tumor xenografts, l-leucovorin significantly enhanced the growth-suppressive ability of UFT against colon carcinoma (KM20C, Col-1) and mammary carcinoma (H-31, MX-1). Among various 5-fluorouracil (FUra) derivatives, such as UFT, 5'-deoxy-5-fluorouridine (5'-DFUR) and FUra, l-leucovorin gave the maximum augmentation to the anti-tumor activity of UFT, due to the prolonged half-life of FUra in plasma. Enhancement of the cytotoxic activity of FUra by l-leucovorin against KM20C colon carcinoma cell line was observed in a time-dependent manner at a concentration of 0.01 microM l-leucovorin. Based on these results, we conclude that the combination of UFT with oral l-leucovorin has significant antitumor activity and represents an interesting regimen to be evaluated in the clinical setting.

Antitumor activity and low intestinal toxicity of S-1, a new formulation of oral tegafur, in experimental tumor models in rats.

S-1, a new oral antitumor agent, is composed of 1-(2-tetrahydrofuryl)-5-fluorouracil (Tegafur, FT), 5-chloro-2,4-dihydroxypyridine (CDHP) and potassium oxonate (Oxo) in a molar ratio of 1:0.4:1. FT which is a masked compound of 5-fluorouracil (5-FU) acts as an effector, while both CDHP and Oxo which do not have antitumor activity themselves act as modulators. In this study, the antitumor activity and intestinal toxicity of S-1 were investigated using experimental tumor models in rats, and compared with those of other oral fluoropyrimidines, namely 5-FU, FT, FCD (1 M FT/0.4 M CDHP) and UFT (combination of FT and uracil). In rats bearing subcutaneous Yoshida sarcoma, S-1 inhibited tumor growth at the lowest dose (ED50 value: S-1 5, UFT 22, FT 82, FCD 5, and 5-FU 19 mg/kg per day), and induced the least host body weight suppression, leading to the highest therapeutic index (TI) (S-1 4.5, UFT 1.4, FT 1.8, FCD 2.0, and 5-FU 1.4). S-1 also showed a higher therapeutic effect than UFT against AH-130 and Sato lung carcinoma. After administration of S-1 and UFT at equitoxic doses, S-1 showed a higher and more prolonged concentration of 5-FU than UFT both in plasma (AUC0-infinity: S-1 28 nmolh/ml, UFT 15 nmol.h/ml) and in tumor tissue (AUC0-infinity: S-1 95 nmolh/g tissue, UFT 52 nmolh/g tissue), leading to a higher 5-FU level incorporated into the RNA fraction (F-RNA level) in tumor tissue (AUC0-24: S-1 7.0 nmolh/mg RNA, UFT 4.3 nmolh/mg RNA) and 5-8% higher thymidylate synthase (TS) inhibition in tumor tissue at every time-point through 24 h. Compared with other oral fluoropyrimidines after administration of the maximal tolerable dose (MTD), S-1 caused the lowest rates of intestinal toxicities, such as diarrhea and occult blood in feces. S-1 also showed a higher antitumor effect on Yoshida sarcoma implanted intracolonically than UFT at an equitoxic dose (tumor weight: S-1 64 +/- 30 mg, UFT 133 +/- 52 mg; P < 0.05). These results suggest that CDHP, which is a potent inhibitor of 5-FU degradation, increases the antitumor activity of FT, and that Oxo, which is an inhibitor of 5-FU phosphorylation, locally protects the gastrointestinal tract from 5-FU-induced toxicity without decreasing the antitumor activity.

Antibacterial activity of TOC-50, a new parenteral cephalosporin against penicillin-susceptible and penicillin-resistant Streptococcus pneumoniae.

TOC-50, a new parenteral cephalosporin, was assessed for antibacterial activity in vitro and in vivo. In vitro, the activity of TOC-50 was greater than ampicillin, erythromycin and gentamycin, and was equal to that of imipenem. The MICs of TOC-50 for 90% of the clinical isolates tested (MIC90 values) were 0.0125 microgram/ml for penicillin-susceptible Streptococcus pneumoniae, 0.2 microgram/ml for intermediately penicillin-resistant S. pneumoniae, and 0.39 microgram/ml for fully penicillin-resistant S. pneumoniae. In murine systemic-infection models, TOC-50 had a potent protective activity against penicillin-susceptible of fully penicillin-resistant S. pneumoniae. Its protective activity was stronger than that of imipenem.

In vitro and in vivo antibacterial activities of TOC-50, a new parenteral cephalosporin, against Enterococcus faecalis.

In vitro and in vivo antibacterial activities of TOC-50, a new parenteral cephalosporin, were assessed against Enterococcus faecalis. In vitro, TOC-50 had excellent activity, stronger than that of penicillin G, sulbactam/ampicillin, tazobactam/piperacillin, the cephalosporins tested, imipenem, vancomycin, gentamicin, tobramycin, arbekacin, amikacin, minocycline and ofloxacin against clinically isolated strains. In addition, TOC-50 was more active than penicillin G, sulbactam/ampicillin and imipenem against vancomycin-resistant E. faecalis NCTC 12201. In terms of bactericidal effect against the same strain, TOC-50 was superior to sulbactam/ampicillin and imipenem. In murine systemic infection models, TOC-50 had a potent protective activity against E. faecalis 42. Its protective activity was stronger than that of imipenem or vancomycin.

[Inhibition of prostate cancer growth in nude mice by hormone and chemotherapy].

The combined effect of hormone and cytotoxic therapy on the growth of prostate cancer PC-3 in nude mice was investigated. PC-3 cell was derived from the bone metastasis of a hormone-refractory prostate cancer. Each group consisted of seven animals. After the inoculation of cancer cells, diethylstilbestrol (DES: 20 mg/kg) and futraful with uracil (UFT: 20 mg/kg) were administered for 25 days. DES and UFT synergically inhibited the growth. DES had no effect as a single agent on the growth of a hormone-independent cell line (KM20C) derived from human colon cancer. It also had no additive effect when given with UFT.

Activity of menogaril against various malignant lymphoma cell lines and a human lymphoma xenograft in mice.

Menogaril is an antitumor agent different from other anthracyclines in that it is active after oral administration; therefore, extravasation is not a side effect. In this basic study, we examined the antitumor activity of menogaril against malignant lymphoma. We compared its activity towards experimental malignant lymphoma with that of Adriamycin, epirubicin, pirarubicin, vincristine, and etoposide, treating mice with each drug at the dose schedule usually used for patients. Menogaril rapidly penetrated lymphoma cells and remained there at least 3 hours after the drug was washed out. Menogaril cleaved more double-stranded DNA in lymphoma cells than Adriamycin, epirubicin, pirarubicin, or etoposide. Menogaril had stronger antitumor activity against experimental malignant lymphoma in mice than Adriamycin, epirubicin, vincristine, and etoposide. Menogaril significantly lengthened the life span of mice bearing one of three lymphoma cell lines resistant to cisplatin, vincristine, or cyclophosphamide. Menogaril had stronger antitumor activity against the human malignant lymphoma xenograft LM-3 than Adriamycin. The strength of the cytotoxic activity of Menogaril might arise from its ready penetration into cells and its cleavage of double-stranded DNA. Therefore, Menogaril might become a useful drug for the treatment of patients with malignant lymphoma by oral administration; 7 days of administration was effective in the in vivo experiments.

Prediction of the optimum clinical dosing schedule for menogaril from results with tumor-bearing mice.

Menogaril is an antitumor agent active after oral administration, and unlike other anthracyclines, extravasation cannot occur. When the IC90 values of menogaril were plotted versus exposure time on a double-logarithmic scale, the regression lines had slopes between -0.64 and -0.80. These results showed that the mode of action of menogaril was type lb, dependent on the area under the curve (AUC) of concentration versus time, like Adriamycin. In calculations that simulated pharmacokinetic findings if administration were for three consecutive days (the single dose given was 79 mg/kg) or on days 1 and 8 (the single dose was 238 mg/kg), the peak tumor concentration of menogaril was 1870 and 2985 ng/g and the AUC was 68,363 and 89,352 ng/g hour, respectively. Of the dosing schedules tried, these two dosing schedules were the optimum, with satisfactory antitumor activity against mouse solid tumor Colon 26 and with a wide range of effective dose concentrations. Since menogaril was AUC-dependent, it was possible to predict antitumor activity and to choose optimum dosing schedules on the basis of cell-kill kinetic and pharmacokinetic information.

In vitro antibacterial activity of TOC-50, a new parenteral cephalosporin against methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis.

The in vitro activity of TOC-50, a new parenteral cephalosporin, was assessed against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE). TOC-50 showed excellent activity, which was stronger than that of methicillin, cloxacillin, the cephalosporins tested, imipenem, gentamycin, minocycline, ofloxacin and ciprofloxacin against MRSA and had a minimum inhibitory concentration (MIC) comparable to that of vancomycin (the MICs of TOC-50 and vancomycin for growth inhibition of 90% of the strains tested were 3.13 and 1.56 micrograms/ml, respectively). Against MRSE, TOC-50 exhibited excellent activity, which was stronger than that of methicillin, ampicillin, the cephalosporins tested and imipenem, and was twice as active as vancomycin. In terms of the bactericidal effect against MRSA, TOC-50 was superior to vancomycin.

Prolongation of survival period and improvement of cancer cachexia by long-term administration of UFT.

We assayed the antitumoral and anticachectic activity of an oral fluoropyrimidine, UFT using the Colon-26-bearing murine cachexia model in terms of the survival period and parameters corresponding to clinical symptoms. Tumor growth was inhibited by UFT dose-dependently at the dose range of 12.5-25.0 mg/kg per day. Although UFT did not show significant growth inhibition at 15.0 and 12.5 mg/kg to which UFT gave little toxicity, the survival period was shown to be superior to the case of maximum tolerated dose (25.0 mg/kg per day). Next, we compared the maximum increase of life span (ILS) value for an administration schedule of continuous 9 days and 5 weeks which mimics the clinical schedule and found that the ILS value in the latter group was superior to the former and UFT improved cachexia, in the same manner. In the following experiments, we have clarified that UFT decreased the level of both plasma interleukin-6 (IL-6) and tumorous prostaglandin E2 (PGE2) and it highly accelerated IL-6 production from Colon-26. These findings suggest that UFT therapy, in low-toxic dose, could be useful to cachectic patients with poor performance status.

[Prolongation of survival and antitumor activity of antitumor drugs in murine cancer cachexia model].

We examined the activity of UFT, ADM and MMC, which are used for colon tumors, in terms of their prolongation of the survival period, growth inhibition of the primary tumor and improvement of cachexia in murine cancer cachexia model. The mean survival period of Colon 26, mouse adenocarcinoma bearing mice was 25.0 +/- 4.9 days. The maximal ILS value of the UFT administered group was 103.2%, against 7.2 and 26.0%, respectively, ADM and MMC maximal ILS value. For therapeutic activity of hypercalcemia, UFT was superior to other drugs, although all drugs showed equivalent tumor growth inhibitory activity. These findings indicate that UFT can prolong the survival period due to improvement of cancer cachexia. Therefore, we measured plasma interleukin-6 (IL-6) and found that UFT-administration lowered the plasma IL-6 level more than other drugs. Moreover, the prostaglandin E2 (PGE2) level in the tumor was significantly decreased only by UFT-administration. Since PGE2 has been shown to enhance IL-6 production from Colon 26 in vitro, it was speculated that UFT improve cachexia and prolongs life by decreased IL-6 resulting from decreased PGE2.

Antitumor activity of 1 M tegafur-0.4 M 5-chloro-2,4-dihydroxypyridine-1 M potassium oxonate (S-1) against human colon carcinoma orthotopically implanted into nude rats.

The purpose of this study was to establish a nude rat orthotopic (organ-specific) human colorectal cancer model as an in vivo secondary screen for general evaluation of new anticancer agents against colorectal cancer and to evaluate practically the antitumor activity of 1 M tegafur-0.4 M 5-chloro-2,4-dihydroxypyridine-1 M potassium oxonate (S-1), a new p.o. fluoropyrimidine, in comparison to 1 M tegafur-4 M uracil [(UFT) effective on colorectal tumor in clinical]. After implantation of KM12C, a human colorectal cancer cell line, into the subserosal layer of the colon as a single-cell suspension, extensive local tumor growth and invasion to both the mucosal and the serosal sides were observed in all rats. Metastatic foci were also formed in both lymph nodes and lungs following local tumor growth in all of them. Using this method, an equitoxic dose of S-1 (15 mg/kg/day) and UFT (30 mg/kg/day) was administered p.o. for 14 consecutive days from 7 days after tumor cell implantation. S-1 showed a higher tumor growth inhibition than UFT did [S-1, 57% (significantly different from the tumor weight of the untreated group at P < 0.05) and UFT, 18% (P > 0.05)]. When both drugs were administered to nude rats bearing KM12C injected into the cecal wall for 28 consecutive days at equitoxic doses, the mean survival in the S-1 group was 16 days longer than that in the untreated group (P < 0.01) but that in the UFT group was only 8 days longer (P > 0.05). After the administration of an equitoxic dose of both drugs, S-1 gave the higher levels than UFT in various pharmacokinetic parameters as follows: area under the curve 0-24 h of 5-fluorouracil in plasma (3.5-fold), area under the curve 0-24 h of 5-fluorouracil incorporated into RNA in the tumor (1.3-fold), and thymidylate synthase inhibition rate (percentage) in the tumor (about 20%). Collectively, these findings suggested that this orthotopic human colorectal tumor model in nude rats is useful to evaluate the clinical therapeutic efficacy of drugs or therapies for colorectal cancer, and that S-1 had a higher therapeutic effect on human colorectal tumor than UFT did.

Antitumor activity of menogaril alone, and in combination against human mammary cancer models in mice and rats.

Menogaril is an antitumor agent different from other anthracyclines in being active after oral administration. To predict its clinical effectiveness by this route against human breast cancer, we compared its antitumor activity against breast cancer in experimental animals with that of injected Adriamycin. Menogaril had half the much antitumor activity of Adriamycin against human mammary cancer cell lines. Menogaril given orally also had a antitumor activity against mammary cancer caused by 7,12-dimethyl-benz[a]anthracene in rats comparable with that of Adriamycin. The high concentration of menogaril in tumor tissue seemed to contribute to its effectiveness. Of several combinations of cyclophosphamide, Adriamycin, menogaril, and 5-fluorouracil, the combination of cyclophosphamide, menogaril, and 5-fluorouracil was most effective against mouse leukemia L1210 and human breast cancer xenografts in mice. This combination might have antitumor activity against breast cancer superior to that of the therapy currently of first choice (cyclophosphamide, Adriamycin, and 5-fluorouracil) in the clinic.