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.

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.

Studies on antitumor agents. 8. Antitumor activities of O-alkyl derivatives of 2'-deoxy-5-(trifluoromethyl)uridine and 2'-deoxy-5-fluorouridine.

O-Benzyl and O-ethyl derivatives of 2'-deoxy-5-(trifluoromethyl)uridine (F3Thd) and 2'-deoxy-5-fluorouridine (FUdR) were synthesized. The oral antitumor activity of the compounds against sarcoma 180 in mice was examined. The 5'-O-ethyl (3b), 3'-O-ethyl (3c), 5'-O-benzyl (3e), and 3'-O-benzyl (3f) derivatives of F3Thd were 4-fold more active than F3Thd itself. Among the substituted-benzyl derivatives of F3Thd, 3'-O-(p-chlorobenzyl)-F3Thd (3h) showed the highest activity, with an ED50 less than one-tenth of that of F3Thd. The activities of 5'-O-benzyl (7c) and 3'-O-benzyl (7d) derivatives of FUdR were equal to those of the effective O-alkyl derivatives of F3Thd.

Studies of antitumor agents. 1. Resolution of racemic 1-(tetrahydro-2-furanyl)-k-fluorouracil into the R and S isomers and examination of the biological activities of the isomers.

1-(Tetrahydro-2-furanyl)-5-fluorouracil (Thf-FU), which is named Ftorafur or FT-207 and is used clinically as an antitumor agent, was conveniently synthesized by condensation of the trimethylsilyl derivative of 5-fluorouracil with 2-acetoxytetrahydrofuran using NaI as a catalyst. This optically inactive Thf-FU was resolved into optically active (R)-(+)- and (S)-(-)-Thf-FU in high optical purity and excellent yield by formation of diastereoisomers with brucine. 13C NMR data were obtained on Thf-FU and related compounds and the antibacterial activities and in vivo antitumor activities of these isomers were tested. The degradations of these isomers to 5-fluorouracil by liver microsomes were also examined. No significant differences were found in any of these properties of these isomers.

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.

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.

Antitumor activity of FTC-092, a masked 5-trifluoromethyl-2'-deoxyuridine derivative.

1-(3-O-Benzyl-2-deoxy-beta-D-ribofuranosyl)-5-trifluoromethyl-2,4(1H,3)- pyrimidinedione (FTC-092), a fluorinated pyrimidine derivative, appeared to be effective against various transplantable tumors in mice following oral administration, and its activity was superior to that of several other antitumor fluorinated pyrimidines. The ED50 value for FTC-092 the dose effective in achieving 50% inhibition of tumor growth against the solid form of sarcoma 180 was 13.3 mg/kg daily, whereas those for 5-trifluoromethyl-2'-deoxyuridine (CF3dUrd), the parent compound of FTC-092, for 1-(2-tetrahydrofuryl)-5-fluorouracil (Tegafur, FT), the prodrug of 5-fluorouracil (FUra), and for FUra were 64.1, 122, and 28 mg/kg daily, respectively. The therapeutic indices (LD10/ED50) of FTC-092, CF3dUrd, FT, and FUra were 4.39, 1.7, 1.35, and 1.65, respectively. FTC-092 itself is not an active agent. After it has been absorbed from the gastrointestinal tract, FTC-092 undergoes a gradual biotransformation, mainly via the action of liver microsomes, releasing CF3dUrd over a long period. The levels of CF3dUrd in the stomach and small intestine of mice after the oral administration of FTC-092 were undetectable, whereas those following the administration of CF3dUrd at the same dose were high for a period of several hours. In contrast, the CF3dUrd level generated in plasma after the administration of FTC-092 remained at a high level for a longer period than did that observed on the administration of CF3dUrd. The low levels of CF3dUrd measured in stomach and small-intestine tissues and the maintenance of CF3dUrd in blood over long periods after the administration of FTC-092 are features that favor the possible clinical application of FTC-092.

Potentiation of the antitumor activity of 5-trifluoromethyl-2'-deoxyuridine by the use of depot forms of the parent compound.

5-Trifluoromethyl-2'-deoxyuridine (CF3dUrd), an antitumor agent, is known to be short-lived in human plasma. Since its rapid elimination from the bloodstream seems to have descouraged the clinical evaluation of this drug, we explored the potential use of masked derivatives of CF3dUrd as "depot" forms of the parent compound. First, we observed that the toxicity of CF3dUrd against HeLA cells in culture was 10(4) times greater for a 24-h treatment as compared with a 1-h treatment at identical concentrations of the drug, which suggests the importance of using a prolonged treatment period. In fact, the divided dosing of CF3dUrd to L1210-bearing mice was markedly more effective than its single administration. 5'-O-Hexanoyl-, N3-p-butylbenzoyl-, 5'-O-benzyloxy-methyl-, and 3'-O-benzyl-CF3dUrd were found to be effective in maintaining the CF3dUrd concentration in plasma. The oral doses of these agents required to achieve 50% growth inhibition (ED50) in mice bearing sarcoma 180 tumors were 19, 34, 10, and 13 mg kg-1 day-1, respectively, whereas that of CF3dUrd was 63 mg kg-1 day-1. The ED50 values for these compounds were inversely correlated with the residence time of CF3dUrd in plasma. The therapeutic indices of these compounds, calculated as the dose producing a 50% inhibition of body-weight gain (IB50) divided by the ED50 value (1.89, 1.21, 1.40, and 2.15, respectively), were significantly higher than that of CF3dUrd (0.78). Consequently, these depot forms of CF3dUrd, particularly 3'-O-benzyl-CF3dUrd, are expected to be more useful than the parent compound as antitumor agents.

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.

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.

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.

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.

Effect of coadministration of uracil on the toxicity of tegafur.

The cardiotoxic and neurotoxic effects of tegafur, an anticancer agent, were compared with those of uracil plus tegafur (4:1 mol/mol) in mice, rats, rabbits, cats and dogs. Uracil plus tegafur was shown to be less toxic than the drug alone in all the species, and uracil was found to decrease the toxicity of tegafur. alpha-Fluoro-beta-alanine, a catabolic metabolite of the drug, had toxic effects similar to tegafur. The results suggest that administration of uracil with tegafur prevents the side effects of the drug on the heart and CNS by inhibiting the degradation of 5-fluorouracil.

Characterization of a new plasmid-mediated extended-spectrum beta-lactamase from Serratia marcescens.

A new extended spectrum beta-lactamase was detected in Serratia marcescens 42039 that was isolated from urine of patients with complicated urinary tract infection in Japan. This stain produced three different beta-lactamase types (TEM-1, a cephalosporinase, and a new beta-lactamase: CKH-1). The TEM-1 and CKH-1 encoding genes were conjugated from S. marcescens 42039 to Escherichia coli K-12 at frequencies of 10(-5) to 10(-6). The MICs of beta-lactams against the transconjugant were: ampicillin > 1600, piperacillin 800, cephalothin 1600, ceftazidime 6.25, cefotaxime 100, and ceftriaxone 200 micrograms/ml. The CKH-1 enzyme was purified to more than 90% by ion-exchange chromatography. The molecular weight of purified CKH-1 was 30 K dalton and the isoelectric point was 8.2. Relative Vmax/Km values (cephaloridine = 100) of penicillin G, cephalothin, and oxyiminocephalosporins such as cefuroxime, ceftriaxone, and cefotaxime, were 256, 226, 116, 87, and 49, respectively. The I50 values of tazobactam, BRL-42715, and clavulanic acid against CKH-1 enzyme were 0.0011, 0.0002, and 0.097 microM respectively. The enzymatic activity of CKH-1 was not inhibited by EDTA and anti-TEM-1 serum. These findings indicate that CKH-1 is a member of the groups of class A beta-lactamases. This is the first report of a plasmid-mediated oxyiminocephalosporin hydrolyzing broad-spectrum beta-lactamase from clinical isolates of S. marcescens.

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.

[Augmentation of chemotherapeutic efficaciousness of UFT by oral l-leucovorin--l-leucovorin factors enhancing cytotoxic activity of 5-fluorouracil].

The relationship between augmentation of cytotoxic activity of 5-fluorouracil (FUra) by l-leucovorin (l-LV) and combination schedule was investigated using human colon adenocarcinoma KM 20 C cell line. The enhancement of cytotoxic activity of FUra by l-LV or 5-CH3FH4, a main metabolite after oral administration of l-LV, was observed after 96-hr exposure to either l-LV or 5-CH3FH4 at concentrations of greater 0.001 microM or 0.3 microM, respectively. We found that 1.5 microM FUra, which has no effect on cell-growth without l-LV, could suppress strongly the proliferation if cells were co-treated with l-LV for more than 8 hr. Therefore, enhancement of cytotoxic activity of FUra by l-LV depended on the time cell exposure to l-LV. Moreover, this effect was observed even at a concentration of 0.01 microM l-LV after 48-hr exposure. Likewise, it is known that the antitumor activity of FUra correlates with the time-schedule of treatment with FUra. These results suggest that in addition to FUra derivatives which continuously release FUra, it is beneficial for the combination therapy of FUra with l-LV to consider continuous administration of l-LV as well.

[The significance of measuring inhibition of thymidylate synthase activity as a parameter for antitumor activity of 5-fluorouracil derivatives].

We investigated the relationships between antitumor activity and the inhibition of Thymidylate Synthase (TS) activity after oral administration of 5-fluorouracil (FUra) and its derivatives, FT, UFT, HC-FU, PH-FU and 5'-DFUR, using mainly Sarcoma 180 as an experimental tumor model. The inhibition of TS activity in the tumor, after oral administration of these drugs to Sarcoma 180 bearing mice, reached the plateau phase shortly after drug administration. The inhibition of TS activity remained at the same level for over 24 hours and was dose dependent. UFT and FT showed a very high correlation between the inhibition of TS activity and their antitumor activity. However, such a correlation was not found for other FUra derivatives despite their high TS inhibiting values. The relationship between the tumor growth inhibition (TGI) and the TS inhibition (TSI) of these drugs, presented as a ratio of ED50 of TGI to ED50 of TSI in case of UFT and FT, was shown to be 0.81 and 1.18, respectively (i.e., nearly 1.00). However, the above ratio for FUra and HCFU was shown to be 2.49 and 3.88, respectively. These findings demonstrate that it is necessary to take into account other mechanisms besides TS inhibition of some fluorinated pyrimidines to explain their total antitumor activity.

[Augmentation of chemotherapeutic efficaciousness of UFT by oral l-leucovorin--growth-inhibitory activity of combination against human tumor xenograft].

Combination chemotherapy with FUra and LV has been reported as a useful treatment for patients suffering from colon carcinoma. Usually, both FUra and LV are administered by intravenous infusion, but not orally. UFT, an anti-neoplastic agent consisting of FT and uracil, is widely used for oral administration in Japan. Using human tumor xenografts of 10 cell lines, we evaluated the efficacy of UFT combined with l-LV, which is the active form of LV, by oral administration. Combined treatment of UFT with l-LV was more effective than UFT alone on the growth suppression of colon carcinoma (KM 20 C, Col-1) and mammary carcinoma (H-31, MX-1). When 1.85 mg/kg (5.55 mg/m2) of LV was given to tumor bearing mice, the antitumor activity of UFT was augmented and at a dose of 5.56 mg/kg (16.7 mg/m2) of LV, it was significantly augmented. Among various 5-FU derivatives, such as UFT, 5'-DFUR or FUra, combined treatment using UFT with l-LV was the most effective by oral administration. l-LV did not improve the anti-tumor efficacy or toxicity of 5'-DFUR. l-LV seemed to augment the anti-tumor activity of FUra, but not significantly. These results suggest that combination chemotherapy of UFT with LV is a promising approach for the clinical treatment of human colon cancer.

[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.