We studied fundamentally subrenal capsule assay, using human tumor specimens (breast, gastric and colon cancers) serially transplanted in nude mice. Mitomycin C, 5-fluorouracil, adriamycin, cisplatinum or cyclophosphamide was injected into immunocompetent CDF1 mice treated with cyclosporin A (CsA) after tumor implantation. On day 6 and day 9 after inoculation, the chemosensitivity profiles of tumor xenografts were similar in CsA-treated mice and nude mice, macroscopically and microscopically. It is suggested that CsA-treated mice were an appropriate model as hosts for chemosensitivity testing. When we examine chemosensitivity effect macroscopically, a method of comparing chemotherapy groups with control groups; i.e. inhibition rate by measurement of tumor volume, was induced, in addition to the tumor size measurement. High toxicity due to cancer chemotherapeutic agents was found in CsA-treated mice, so that careful examination on treatment schedules with CsA and chemotherapeutic agents will be required.

In clinical chemotherapy with neocarzinostatin (NCS) against cancers, side effects such as leukopenia, anorexia, vomiting and nausea were mainly observed when parenteral administration was used. To prevent these adverse side effects without changing the anticancer activity of the drug, we attempted to apply the two-route-infusion chemotherapy using NCS and antidotes for the NCS treatment devised by Baba. This report presents the results of our study on effects of some antidotes on the acute toxicity of NCS in mice and also on the antitumor activity of NCS against Sarcoma-180 in mice (ICR-JCL strain) when used with tiopronin. The results are summarized as follows. 1. LD50 values of NCS administered via intravenous route increased 2.3- to 3.2-fold when 150, 300, 500 or 1,000 mg/kg of tiopronin was administered subcutaneously together with NCS, 1.3- to 1.4-fold when 50 or 100 mg/kg of sodium thioglycolate was used. When antidotes were given prior to the administration of NCS, 1.8- to 5.4-fold increase in LD50 values of NCS resulted with 300, 500 or 1,000 mg/kg of tiopronin administered 1 hour prior to NCS, 2.3-fold increase resulted with 2,000 mg/kg reduced glutathione, 1.2-fold increase with 100 mg/kg of sodium thioglycolate and 1.9-fold increase with 1,000 mg/kg of L-cysteine monohydrochloride monohydrate. Furthermore, 4.8- to 13.1-fold increase in LD50 of NCS occurred when 150, 300, 500 or 1,000 mg/kg of tiopronin was administered 15 minutes prior to NCS. When these antidotes were administered 1 hour after the administration of NCS, however, no changes in the LD50 value occurred. 2. The LD50 value of NCS given intraperitoneally increased 1.6- to 5.8-fold when 150, 300, 500 or 1,000 mg/kg of tiopronin was administered intravenously at the same time as NCS, 1.4- to 1.6-fold when tiopronin was given 1 hour prior to NCS, intraperitoneally and 1.3- to 1.7-fold when it was given 1 hour after NCS. 3. It was recognized that the acute toxicity of NCS was the most effectively reduced by tiopronin, but only slightly by glutathione, sodium thioglycolate or L-cysteine monohydrochloride monohydrate. The action of tiopronin was the most effective when it was given subcutaneously 15 minutes prior to NCS administered intravenously. 4. The combination chemotherapy on Sarcoma-180 in mice using NCS intraperitoneally and tiopronin intravenously was markedly effective when these agents were given simultaneously.

It has been generally recognized that in a variety of biological systems the structural changes such as circularization, looping and supercoiling of DNA play important roles in carrying out genetic processes such as replication, transcription, recombination etc. Since the discovery of DNA topoisomerase I in 1971 (then named omega protein) in E. coli type I and type II topoisomerases have been found in a wide variety of organisms. In addition the finding that these enzymes are the only ones which can cope with the torsional strain accumulating within the DNA molecules carrying out the genetic processes by swiveling the strands through breakage and rejoining of phosphodiester bonds strongly suggests that they are involved in various aspects of DNA metabolism such as replication, transcription, recombination, differentiation etc. In this article the function of DNA topoisomerases elucidated so far in prokaryotic and eukaryotic cells with special emphasis on their roles in gene expression has been briefly reviewed.

Dual parameter analysis of FCM using rhodamine 123 (R 123) and propidium iodide (PI) has made it easy to estimate cell viability. PI stains only dead cells, whereas R 123 accumulates in the mitochondria of living cells which remain unstained by PI. Therefore the combination of R 123 and PI provides a more accurate estimation of cell viability than the conventional methods of dye exclusion. Cell viability has been estimated by this method in HeLa cells treated with adriamycin in vitro. The usefulness of this analysis is suggested for the evaluation of the effect of anticancer drugs on tumor cells.

We administered Bestrabucil, a benzoate ester of a complex of beta-estradiol and chlorambucil, continuously to six patients with breast cancer recurrent to local and regional lymph nodes, at a dose level of 200 mg/day. Of these six cases, one achieved CR, two PR, one MR, and two were NC. The drug was thus effective in 50% of the cases, with mild side effects. At the same time, since the concentration transfer to lymph nodes was satisfactory, Bestrabucil was thought to be an effective drug for the treatment of locally recurrent breast cancer.

After examining the in vitro cell-kill kinetics of various anticancer drugs by using cultured human cell lines, Shimoyama et al. classified the drugs into two groups according to the types of action: 1) type-I drugs (cytocidal and concentration-dependent action) such as alkylating agents and anticancer antibiotics; 2) type-II drugs (cytostatic and time-dependent action) such as antimetabolites, Vinca alkaloids and L-asparaginase. In the present paper, we will present a rational basis for such a classification by using cell-kill pharmacodynamic models, and consider the optimal dosage regimen depending on the type of drugs by combining the cell-kill kinetic and pharmacokinetic models. In these models, classification of the drugs depends on whether the cell population is kinetically homogenous or not. It is assumed that cell population is homogenous for type-I drugs and there exist both drug sensitive and insensitive cell populations for type-II drugs. The concentration (or dose)-time-cell survival curves in both in vitro and in vivo, which are simulated based on the kinetic models, are consistent with the experimental data found in the literature. Further analysis on the optimal dose regimen according to these kinetic models clarified that the type-I drugs showed a similar cell-kill effect irrespective of the mode of administration as long as the area under the plasma unbound concentration curves (AUCp, free) is kept constant, while the type-II drugs are more effective by multiple dosing or infusion regimen than single administration of a large dose of drugs. In other words, the extents of AUCp, free and the residence time in the plasma (above certain concentrations of drugs) are determinants of the in vivo cell-kill effects of type-I drugs and type-II drugs, respectively. If the pharmacokinetics of newly developed anticancer drugs in human are predicted from the animal data according to the so-called "animal scale-up" technique and combined with the in vitro cell-kill kinetic data by the use of proposed kinetic models, one may obtain not only the optimal dosage regimen but also good screening systems for truly active drugs for the treatment of human cancer.

Growth inhibitory effects of neocarzinostatin (NCS), and its conjugated derivative with poly (styrene-maleic acid), SMANCS, were examined on various tissue culture cells consisting of 13 lymphatic and 7 non-lymphatic cells (15 cell lines, 5 primary culture cells; 14 in suspension culture cells, 6 in monolayer cells). Both agents showed almost similar concentrations for the growth inhibition against 5 non-lymphatic cell lines (an average minimum growth inhibitory concentration of NCS, 0.076 microgram/ml, and SMANCS, 0.094 microgram/ml, a ratio of 1 : 1.24 (W/W), or 1.0 : 0.9 (mol/mol]. However, SMANCS showed a much less growth inhibitory effects against lymphatic 10 cell lines than NCS. Namely, an average 50% growth inhibitory concentration of NCS was 0.019 microgram/ml whereas that of SMANCS was 0.091 microgram/ml (a ratio of 1 : 4.79). From the consideration of each molecular weight, this ratio is 1 : 3.6. Similar results were obtained in experiments in which 2 primary non-lymphatic cells and 3 primary lymphatic cells were used. Although the largest drawback with NCS was known to be leukopenia, present results indicated the less toxicity of SMANCS than NCS on lymphatic cells and may provide a positive aspect of the new derivative, such as less incidence of leukopenia.

The cytotoxicity of peplomycin modified by cepharanthine, was studied on in vitro cultured Chinese Hamster V-79 cells. Cepharanthine alone showed almost no cytotoxicity on this tumor system. It was revealed that cepharanthine enhanced the cell killing action of peplomycin and also promoted the recovering process from the effects of peplomycin. The enhancing effect increased with an increase of the concentration at the lower concentrations but there were limitations at the higher concentrations. The bi-phasic properties specific to peplomycin on the dose-survival curves were unchanged even in combination with cepharanthine was observed in the recovering process from the effects of peplomycin. From these results, cepharanthine seemed not to affect on the mechanism of action of peplomycin.

The antitumor activities of several chemotherapeutic agents were tested in the human tumor clonogenic assay (HTCA) and in subrenal capsule assay (SRCA). The results obtained in these two assays and clinical response were compared. 1. Colony growth was observed in 43 of 73 tumors (58.9%), and the adequate colony growth to evaluate the response of therapeutic groups was obtained in 21 tumors (28.8%). 2. Control growth adequate to meet evaluable assay criteria was obtained in 38 of 43 tumors (88.4%). 3. With activity criteria set at a decrease of greater than or equal to 50% in tumor colony-forming units for the HTCA and a change in tumor size less than or equal to -1.0 dmm for the SRCA, 24 of 98 drugs tested were active in HTCA (24.5%), and 50 of 160 drugs were active in SRCA (31.2%). 4. A total of 21 tumors was tested in both HTCA and SRCA and the tumor response was compared in 12 tumors treated with 39 drugs. Correlation of tumor responses between the two assays was 71.8%. 5. A total of 8 HTCA-clinical correlations and 5 SRCA-clinical correlations were possible. Overall predictive accuracy was 87.5% in the HTCA and 80.0% in the SRCA, respectively.

Antitumor efficacies of five antineoplastic agents, cisplatin, mitomycin, doxorubicin, 5-fluorouracil and bleomycin were tested against the human carcinoma of the uterine cervix xenografted into nude mice in order to search for effective combination chemotherapy. Antineoplastic agent was administered i.p. 6 times once a week to nude mice with tumor growing to 8-10 mm in diameter. The effect in each group was evaluated by Battelle Columbus Laboratories' method, measuring at 6th week the tumor growth rate in the treatment group (Tn/T0) and in the control group (Cn/C0) where the comparative tumor growth ratio (Tn/T0/Cn/C0) was taken as the index. As the result, the response rates of cisplatin and mitomycin on the tumor growth were high as 83.3% and 66.7% respectively. It is concluded that combination chemotherapy including cisplatin and mitomycin is recommendable for the treatment of squamous cell carcinoma of the uterine cervix.

Surgical tumor specimens from 67 urological malignancy patients were subjected to a human tumor clonogenic assay (HTCA) developed by Hamberger and Salmon. Appreciable growth of colonies was obtained in 20 of the 33 renal cancers, 20 of the 30 urothelial cancers and 1 of the 4 testicular cancers examined. Using HTCA, a plating efficiency ranging from 0.01 to 0.5% was obtained in these urologic malignancies. However, colonial growth adequate for chemosensitivity was obtained in 30 of these 67 patients. According to Von Hoff's definition, more than a 70% decrease in the plating efficiency after anticancer drug exposure was defined as susceptible. Susceptibility to vinblastine (VBL) was seen in 4 of the 11 patients with renal cancer. Susceptibility to cis-dichlorodiamine platinum (CDDP) was seen in 4 of the 15 patients with urothelial cancer, 1 of the 4 patients with renal cancer, and that to adriamycin (ADM) was seen in 3 of the 15 patients with urothelial cancer, 2 of the 10 patients with renal cancer and 1 patient with testicular cancer. For comparison, the ratio of IC90 to the peak plasma concentration of the drug tested was used as the "in vivo-in vitro therapeutic index (TI)". According to TI, susceptibility to VBL was seen in 3 of the 7 patients with renal cancer, and that to CDDP was seen in 2 of the 12 patients with urothelial cancer, and 1 of the 2 patients with renal cancer. Susceptibility to ADM was seen in 3 of the 15 patients with urothelial cancer, and 1 of the 6 patients with renal cancer.(ABSTRACT TRUNCATED AT 250 WORDS)

The development of suitable screening systems is one of the most important determinants for the successful discovery of new anti-tumor drugs. The National Cancer Institute, U.S.A. has been playing a major role in the discovery and development of new agents by using various animal tumor models since 1955. In this article, the historical overview of this effort, and the difficulties and problems of this approach was reviewed. Also the new "Disease-Oriented Screening System", which is now under development as a new screening system at the National Cancer Institute was also described.