The usefulness of in vivo-like culture system using a specialized collagen gel matrix (Spongostan) derived from pigskin was summarized. In this culture system, the in vivo properties maintained in vitro, showing three-dimensional growth; maintenance of tissue architecture. This culture system was applied for the chemosensitivity test using human cancer specimens. There was a close association between the results of this assay and those of the nude mouse assay. Moreover, this system could be useful for the prediction of drug sensitivity against human cancers obtained from a surgery and biopsy, including scirrhous type gastric carcinomas. This in vitro assay system seems to be a promising method for chemosensitivity test, because of its rapidity and convenience.

A phase II study of 254-S was conducted in 134 patients with gynecological malignancies by the gynecology section of the 254-S cooperative study group. The drug was administered at least twice at a dose of 100 mg/m2 by intravenous infusion at 4 week intervals. Forty-two of the 102 evaluable patients responded, including 8 CRs and 34 PRs, with a response rate of 41.2%. The response rate was 37.7% for ovarian cancer and 46.3% for cervical cancer. The response rate of 46.3% for cervical cancer was the highest reported for any single anticancer agent available in Japan. The major side effect was hematotoxicity, in particular thrombocytopenia and leukopenia, while nephrotoxicity was rarely observed. These results suggest that 254-S is an active cisplatin analogue with reduced nephrotoxicity and is a very promising anticancer agent for the treatment of ovarian and cervical cancer.

Phase I study of DWA2114R, a new platinum analogue, was conducted in 39 patients with various tumor types by a group of 13 institutions. Of the 39 patients entered in this study, 35 were evaluable. The starting dose was 40 mg/m2 (1N) and the drug was administered i.v. for 20-30 min, escalating stepwisely up to 1,000 mg/m2 (25 N). The dose limiting factor (DLF) was leukocytopenia, especially neutrocytopenia, and the maximum tolerated dose (MTD) was more than 1,000 mg/m2. Major clinical toxicity was gastrointestinal. Hepatotoxicity and nephrotoxicity were mild. Following administration of the drug, plasma concentrations of total and filterable platinum (Pt) showed a triphasic and biphasic decays. Excretion into urine within 24 hours was in the range of 54.2% to 92.2% of the administered platinum. The recommended dose of phase II study was 800-1,000 mg/m2, repeating every 3-4 weeks.

New strategies in antineoplastic therapy that have been applied during the last 5 years to children with malignant disease include the Goldic-Coldman hypothesis, new methods of drug delivery, reduction in toxicity with prolonged intravenous infusions, shortening of maintenance therapy and techniques to improve the compliance of adolescents and older children with prescribed therapy. These new concepts of chemotherapy in developmental pharmacology to treat cancers in children are reviewed.

Metallothionein (MT) in tumor cell has been indicated as one of the factors involved in the mechanism of resistance to anticancer drugs. The relationship between expression of MT and chemotherapy with anticancer drugs was studied with bladder cancer culture cell lines and tissue samples from clinical cases. In drug-resistance cell lines, MT expression was studied by immunohistological staining of the avidin -biotin peroxidase complex (ABC) method, and by the radioimmunoassay (RIA) method, using an anti-MT antibody. As for tissue samples from clinical cases, 114 paraffin embedded samples of 29 cases before and after chemotherapy were subjected to immunohistological staining of MT. Human-bladder cancer cell lines with resistance to anticancer drugs (C1-7/CDDP, T-24/ADM) showed increased of expression of MT compared to each parental cell lines (C1-7, T-24), suggesting relationship of resistance to anticancer drugs and MT expression. In the clinical cases, those with continuous administration such as intra-vesicle chemotherapy or oral administration chemotherapy showed greater incidence of positive staining of MT expression in comparison with cases with fewer administrations, such as intra-arterial infusion therapy or intravenous administration chemotherapy. These results demonstrated that repetitive and continuous administration of anticancer drugs cause increase of MT in bladder cancer cell, which may be a possible mechanism of acquired resistance to anticancer drugs.

Metallothionein (MT) is a low molecular-metal binding protein with multiple biological functions. Recently, MT has been implicated as a factor involved in resistance to anticancer drugs, which presumably inactivates anticancer drugs, including cisplatin, and doxorubicin. In this report, we investigated the relationship of MT expression with the clinical features in bladder cancer and renal cell carcinoma. In 35 cases of bladder cancer, 10 cases of renal cell carcinoma and 3 cases of normal mucosa of bladder, the expression of MT was immunohistologically examined by avidinebiotin-peroxidase (ABC) staining of paraffin-embedded tissue specimens with anti-MT antibody. Intense MT expression was noted in all cases of normal mucosa of bladder. MT was detected in 10 of 35 cases of bladder cancer, with the incidence of MT expression being significantly higher increases with lower pathological tumor grade. MT was detected in 8 of 10 cases of renal cell carcinoma, and all of the their normal renal tubules showed more intense staining. A number of hypotheses can be proposed from these observations. First, our observation of decreased MT expression in poorly differentiated carcinomas, which are the more proliferating tumors, this suggests correlation of MT expression with proliferative status of cancer. Second, the higher incidence of MT expression in renal cell carcinoma than in bladder cancer may suggest that it is a factor responsible for the lower efficacy of chemo-therapy in renal cell carcinoma than in bladder cancer.

Kazusamycin A (KZMA) is a new anticancer antibiotic, which has been proven to have strong anticancer effect and several characteristic features different from currently available anticancer antibiotics. However, there has as yet been no report which had concerned itself with the effect of KZMA on urological cancer. This study was undertaken to determine the inhibitory effects of KZMA on transitional cancer cells in vitro, the augmentation of the inhibitory effect by combining thermal treatment and the effect of KZMA upon DNA distribution. Human transitional cancer cells, KU-1, and T-24 were used as targets. Fifty % inhibitory concentration of KZMA was determined after these cells were exposed to graded concentrations of KZMA for 2 to 48 hours, and to the concentration of KZMA for 2 hours at the temperature of 42 degrees C. Viable cells were counted by dye exclusion assay (DEA) and by tetrazolium-based colorimetric assay (MTT-assay) exposure. KZMA inhibited the growth of the three transitional cancer cells strongly and this inhibitory effect appeared to be depend upon the exposure time and the concentration of KZMA. IC50s after 2-hour exposure at the temperature of 42 degrees C was shown to be decreased to 23 to 87% of that at the temperature of 37 degrees, indicating an augmentation of the inhibitory effect of KZMA by combining thermal treatment. MGH-U1 was the most sensitive to the combination of KZMA and hyperthermia. The cell cycle analysis showed that KZMA had G2-arresting and M-retarding effects, which were different compared with currently available anticancer antibiotics.(ABSTRACT TRUNCATED AT 250 WORDS)

A phase II clinical study of 254-S, a new anticancer platinum complex for gastrointestinal cancers, was conducted by the 254-S Gastrointestinal Cancer Study Group consisting of 16 institutions. 254-S was administered at 100 mg/m2 by intravenous drip infusion. This administration was repeated at 4-week intervals. The cases in which 254-S could be administered at least two times were regarded as complete cases evaluable for tumor response; of 75 cases registered, 53 were complete cases (29 cases with esophageal cancer, 12 with stomach cancer and 12 with colon cancer). As a result, 15 partial responses (PR) were obtained in the 29 patients with esophageal cancer and 1 PR from the 12 patients with stomach cancer, for a 51.7% and 8.3% response rate, respectively. 5 PR (55.6%) were obtained in 9 esophageal cancer patients with prior chemotherapy, including 2 PR in 4 patients previously treated with cisplatin. Major toxic effects observed were hematotoxicity including thrombocytopenia (59.0%), leukopenia (68.9%) and anemia (57.4%) and gastrointestinal toxicity such as nausea and vomiting (63.9%) and anorexia (41.0%); since grade 3 or 4 thrombocytopenia was observed with an incidence of 27.9%, careful monitoring seems to be required during the treatment with this product. Abnormal parameter changes on renal function included elevations of BUN (18.0%) and serum creatinine (9.8%). Based on these results, it was concluded that 254-S is a useful anticancer agent for the treatment of esophageal cancer.

Pharmacokinetics of SM-5887, a new totally synthetic anthracycline derivative, was studied in a phase I setting by 5-day schedule. The maximum tolerated dose was 25 mg/m2/d (total dose: 125 mg/m2/body) and the dose-limiting toxicity was myelosuppression which was consistent with the results of the phase I study by a single dose. In terms of subjective side effects, decreased nausea/vomiting and increased stomatitis were observed. In pharmacokinetic study, AUC of active form of SM-5887 increased on day 5 compared to that day 1. This result suggested that 5-day schedule of SM-5887 produced an accumulation of the active form. Five-day treatment schedule of SM-5887 seems to be more tolerable and further clinical study was recommended.

The (-) - (R) - 2-aminomethylpyrrolidine (1, 1-cyclobutanedicarboxylato) platinum(II) monohydrate, DW A2114R, is a new derivative of cis-dichlorodiammineplatinum(II), CDDP, which is reported to have a lower nephrotoxicity than CDDP. In this report, we investigated the effects of DW A2114R, in comparison with CDDP, on the cell growth, the cell cycle traverse and the colony-forming ability of human leukemia RPMI 8402 cells in vitro. The inhibitory effects of DW A2114R on the cell growth and the colony-forming ability were about 1/10 and 1/10-1/30, respectively, of the CDDP dose. And DW A2114R showed a higher time-dependency than CDDP in the experiment comparing exposure time to the drugs. Analysis of DNA histograms obtained by flow cytometry revealed that DW A2114R had a similar effect on the cell cycle traverse to that of CDDP. Both drugs exerted their growth-inhibitory effect by blocking cells at G2 phase. At higher concentrations, they prolonged the traverse of cells through S phase and completely inhibited them throughout the cell cycle. The comparative study on the colony-forming ability suggested that the G2 phase accumulation was irreversible and that these drugs are lethal, so the G2 phase accumulation could be considered a cytocidal effect of the drugs. In early clinical studies, however, the dose of DW A2114R was put at about 15-fold higher than the therapeutic dose of CDDP. This was comparable with our results in vitro and DW A2114R showed a much lower toxicities, with special regard to nephrotoxicity, than CD DP. These clinical data and our results suggest that DW A2114R could be clinically effective as an antitumor agent.

For the purpose of establishing a method for reasonable clinical use of anthracyclines in leukemia chemotherapy, we examined the pharmacokinetics and the mode of action with five anthracyclines such as daunorubicin (DNR), doxorubicin (DOX), aclarubicin (ACR), THP adriamycin (THP), idarubicin (IDA). In the patients with AML, blood ACR or IDA level increased and then disappeared very rapidly after iv bolus injection. In contrast, their metabolites (M1 or IDAol) increased for up to 2 or 4 hrs and remained much longer than ACR or IDA. The concentration of ACR, IDA or their metabolites were found to be much higher in the leukocyte fraction than in erythrocyte fraction or plasma. In HL60 cell suspension, anthracyclines were rapidly accumulated into the cells, and the uptake of IDA or THP were higher than the other agents. In HL60 cells, anthracyclines accumulated in the nuclear fraction but ACR was accumulated markedly in the cytosol fraction. From the result of DNA binding assay, binding at excess to calf thymus DNA of ACR was suggested to be approximately 2 times higher than that of other agents. DNA strand brakes in HL60 cells treated with anthracyclines were shown by pulse field gel electrophoresis, and IDA was found to have stronger activity to cause the DNA strand breaks. In conclusion, it seemed that anthracyclines showed similar action mechanisms, but in some respects quantitative differences were existed among them. Anthracyclines should be given to patients based on their pharmacological characteristics to obtain higher remission rate and suppress resistant cells.

dFdC (2',2'-difluorodeoxycytidine; LY 188011), a new analogue of ara-C, which contains fluorines in the sugar moiety, has shown a wider antitumor spectrum and has effective to solid tumors, as compared with ara-C. The pharmacokinetic behavior of dFdC was compared with that of sera-C or BH-AC (N4-behenoyl ara-C) using experimental animals. The results were as follows. 1. Plasma levels (rabbits): The half-lives of dFdC were longer than those of ara-C. The peak level of ara-C, which derived from BH-AC, was not so high but continued for relatively a long time. 2. Tissue levels (S.180 tumor bearing mice): dFdC levels were high in the spleen and thymus, tumor, testis and muscle, and persisted longer than ara-C. The levels of ara-C derived from BH-AC were low, but persisted for a long time. 3. Inactivation: The grade of inactivation of dFdC to dFdU was observed as same as that of ara-C to ara-U. dFdC was rapidly phosphorylated to dFdCTP in tumor cells, and dFdCTP accumulated higher, when compared with ara-CTP. Clinically, the determinations of unchanged drug levels in the plasma, and the dFdCTP, ara-CTP and dCTP levels in tumor tissue seemed to be important.

We succeeded in establishing a cell line (KEN-3) for subculture from a fibrosarcoma which originated in the ovary in a girl aged 17 years. Its characteristics and sensitivity to anticancer agents are reported in this paper. 1. Characteristics of established cell line. Lined cells consist of multinucleated giant cells mixed among many spindle-shaped cells. They grow in small colonies and have none of the pavement-like arrangement characteristic of epithelial tumor cells. The number of chromosomes ranged from 45 to 128 (mode: pseudo-triploidy region, 65). The doubling time, cellular density and plating efficiency were 76.9 hours, 5.4 x 10(5)/cm2 and 30.2%, respectively. Concerning tumor markers, CEA and sialyl SSEA-1 were only produced in small quantities. Subculture was possible subcutaneously in the nude mouse with no capacity for the production of ascites. 2. Susceptibility to anticancer agents and GP170 expression. The in vitro susceptibility to about 12 types of anticancer agents was investigated with the MTT assay. IC50/PPC was shown to be less than 1 for Adriamycin only. The sensitivity to CDDP (IC50/PPC: 4.8) was low, and no sensitivity was observed at all to DTIC, which is used frequently for mesenchymal tumors. GP170 (mdr-1 products) was positive in established cells in immunohistochemical stain.

III Purine antagonists Biosynthesis of guanine nucleotides has been reported to be up regulated in tumor cells. In guanine nucleotide synthesis, there are 2 rate-limiting enzymes, i.e. inosine monophosphate dehydrogenase for de novo synthesis and hypoxanthine guanine phosphoribosyltransferase for the salvage pathway. Therefore, agents acting on these 2 enzymes to inhibit guanine nucleotide synthesis could be expected to have a superior effect on tumor proliferation. The main antitumor agents belonging to this class are thiopurines [including 6-mercaptopurine (6 MP), 6-thioguanine (6 TG) and 6-thioinosine (TIR)], thiazofurin (TZF), and arabinofuranosylfluoroadenine (F-ara-A). In the activation of 6MP to its ribotide. PRPP is the rate limiting factor. After the ribotide is produced, it is metabolized to another active form by enzymes catalyzing purine nucleotide metabolism. The antitumor effect of TZF is enhanced by the combination of TZF with allopurinol, which increases the plasma hypoxanthine level and subsequently inhibits recovery of the reduced guanine nucleotide pool by TZF. F-ara-A induces DNA strand damage as well as inhibiting DNA synthesis and is expected to have a significant antitumor effect on slowly growing tumors. These agents are mainly effective for treating hematological malignancies. IV Antifolic agents Among the antifolates, methotrexate (MTX) is the most useful drug for both hematologic malignancies and solid tumors. MTX primarily inhibits one-carbon transfer through the inhibition of dihydrofolate reductase and thus blocks the biosynthesis of both purine and pyrimidine nucleotides. Formyl polyglutamate synthetase catalyzes folate to its polyglutamate, both the active and retention forms. It is also important as an activating enzyme as well as being a target of MTX. MTX directly inhibits thymidylate synthetase, which could be the main target during high-dose therapy. High-dose MTX therapy with leucovorin (LV) rescue is effective even for tumors which are resistant to conventional treatment. During clinical use, not only MTX levels but also those of its inactive metabolites [7-hydroxy-MTX and 2, 4-diamino-N10-methylpteroic acid(DAMPA)] should be monitored. High-dose MTX therapy with LV rescue requires precise monitoring and LV rescue should be continued until the MTX level falls below 5 x 10(-8) M. MTX is also known as the safest drug which can be directly administered to into the central nervous system. Many other antifolates are under development, among which trimetrexate might be the most promising. Studies on antimetabolites have developed side by side with research on nucleotide tumor cell metabolism, which has produced a number of the antitumor agents now available for cancer chemotherapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Pirarubicin (THP) is a derivative of adriamycin (ADM) which has been reported to have a lower cardiotoxicity than ADM. The authors investigated the in vivo antitumor effect of THP against human colon cancer cells (RPMI 4788) xenografted into nude mice. In the model of intra-abdominal carcinomatosis, intraperitoneal administration of THP (6 mg/kg) resulted in a significant prolongation of the survival compared with the saline control group (p less than 0.01). Intravenous administration of THP (8 mg/kg) significantly inhibited tumor growth compared with the saline control group. Labeling index with bromodeoxyuridine (BrdU) of RPMI 4788 tumors treated with THP was smaller than that in the control group. Mitotic index was also smaller in the group treated with THP. Labeling index with BrdU indicates the proportion of cells in the S phase. Thus, the tumor cells in both S and M phases have decreased after treatment with THP. This change in the cell cycle progression may be due to the accumulation of G2 phase similar to in vitro study. From these results, it was suggested that the change in cell cycle progression revealed in vitro might be caused by THP in vivo.