We examined an application of in vitro fertilization--embryo culture--embryo transfer system for reproductive and developmental study on the drug safety evaluation in mice. The male mice at 10 weeks of age were administered intravenously with a single dose of 75 mg/kg of the anticancer platinum complex (DWA 2114R) which inhibits DNA synthesis. Four to six weeks after administration, the males were mated with the superovulated females. Fertilization rates were significantly lower than the controls at each weeks after the administration. Furthermore, delayed formation of pronucleus was observed as compared with the control. Four weeks after administration, the preimplantation development to blastocyst stage of those embryos in vitro and the survival rates on the day 17 of gestation after embryo transfer suggested that a DNA synthesis in germ cells during maturation was inhibited and/or prevented by DWA 2114R. The results of in vitro fertilization reflected its sperm concentration rather than the administration of DWA 2114R. Thus, an analysis of the delayed formation of pronucleus observed fertilization in vivo could not done in detail. To use for the drug safety evaluation, there exist plenty of room for improvement in this system. These results have showed that the embryo culture and the embryo transfer are useful techniques as the reproductive and developmental study on the drug safety evaluation. These techniques bring additional informations on the pre- and post-implantation development in vivo.

Accumulating evidence indicates that the activation of cellular oncogenes is a cause of some human cancers. ErbB-1, erbB-2 and abl oncogenes encoding tyrosine kinases, ras oncogenes encoding GTP binding proteins and myc oncogenes whose functions are not well understood are some examples. Therefore, agents which inhibit the activity of these oncogene products may provide new means to overcome certain human tumors. Herbimycin A and tyrphostins have been found and developed as inhibitors of tyrosine kinases and the effectiveness of these agents against tumors of Ph1-positive leukemia (CML, ALL) or squamous cell carcinomas has been reported. Although specific inhibitors of ras or myc oncogene products have not yet been described, recent studies on the processing of Ras proteins toward the cell membrane provide a strategy to search for inhibitors of ras functions.

Cytarabine ocfosfate (commercial name: Starasid) is a prodrug having stearyl group attached to phosphoric acid at 5' position of arabinose moiety of cytosine arabinoside (Ara-C). This drug is given orally. The mode of action is in the inhibition of DNA synthesis after conversion to Ara-CTP as in Ara-C. The drug is metabolized in the liver, producing the intermediate metabolite, C-C3PCA which is converted to Ara-C gradually. This property results in the maintenance of relatively long time the blood Ara-C levels. This was proved to be active clinically against acute leukemia and MDS.

Studies of anticancer pharmacodynamics were reviewed. Pharmacodynamics deals with the relationship between therapeutic or toxic response and pharmacological measurements. It is suggested that the lack of pharmacodynamic information is currently limiting the application of pharmacokinetic information to cancer therapy. The studies contain pharmacodynamics of hematologic and non-hematologic toxicities, tumor response and cellular pharmacodynamics. It would be desirable to develop pharmacodynamic models using a limited sampling model during phase II trials, when all patients are treated with the same recommended dose, to relate pharmacokinetic parameters to tumor responses. The return knowledge of pharmacodynamics to cancer chemotherapy makes the concept of individualized therapy, adaptive control strategy with feedback (ACF) and targeted systemic exposure strategy (TSES). St. Jude Children's Research Hospital is now performing a randomized prospective trial to evaluate the efficacy and toxicity of conventional dosages versus individualized therapy using TSES with ACF in Acute lymphocytic leukemia pulse therapy with high-dose methotrexate, teniposide, and cytarabine. It would be a good model for the establishment of oncological pharmacology-based optimal administration of anticancer drugs.

In the aspects of pharmacodynamics of antitumor agents, the blood level of administered drug is elevated first and maintained for a certain period of time. Then the drug reaches to tumor cells and is incorporated into the cells. After activated, it induces damage of DNA strands, inhibition of DNA synthesis and suppression of the cell proliferation. Each agent shows different behavior in each step of pharmacodynamics. 1) Blood drug level; distribution of antitumor agent in red and white blood cells, and plasma after administration is different among drugs. Lipophilic drug such as behenoyl ara-C is well absorbed and stored in red blood cell membrane, which is re-utilized effectively for the maintenance of plasma drug levels. Drugs having strong DNA binding affinity such as anthracycline, are accumulated in white blood cells and their blood levels are correlated with the white blood cells counts. 2) Incorporation of antitumor agents into the cells; especially incorporation of nucleoside analogs are correlated with the number of nucleoside transport sites of the cell membrane. Drug incorporation is also greatly influenced by activation and inactivation of drug in the cells. 3) Activation of the drugs in the cells; the activation reactions require the corresponding enzymes and cofactors. Activation of ara-C depended on deoxy cytidine kinase activity, whereas activation of 6-mercaptopurine required hypoxanthine guanine phosphoribosyl transferase and phosphoribosyl pyrophosphate. The latter is the limiting factor of the activation reaction. In a case of rapid activation of a certain drug, such as ara-C, in a cell suspension, intracellular concentration of its active form exceeded extracellular concentration of the drug within 10 min of the incubation time. 4) Effects of nucleotide pool changes by antitumor agent on activation of the other antitumor drug; inhibitors of riboside diphosphate reductase, such as fludarabine or hydroxyurea, reduced deoxynucleoside triphosphates pools, and the reduction resulted in the decrease of feedback inhibition of deoxy cytidine kinase. Subsequently, activation of ara-C to its nucleotides was increased. 5) DNA damage by antitumor agents and its repair; a part of DNA damages induced by labile DNA binder are repaired. Inhibition of the repair would be effective for increasing antitumor effects. 6) Suppression of drug inactivation; in a case of ara-C, inactivation is nearly 100 times higher than activation. A number of procedures for suppressing the drug inactivation have been investigated to increase production of intracellular active form of the drug.(ABSTRACT TRUNCATED AT 400 WORDS)

DN-9693, c-AMP: phosphodiesterase inhibits platelet aggregation induced by metastasizing tumor cells and blood-borne metastases of these tumors. Effects of this drug on pulmonary metastases was studied in wKA rats, which were sc implanted with 4-dimethylaminoazobenzene (DAB) induced KDH-8 tumor cells. KDH-8 cells (10(5)) were sc inoculated on day 0 and excised on day 20. DN-9693 was ip injected at a dose of 150 micrograms twice a day for 7 days pre operatively (-7 - 0) or perioperatively (-3 - +3) or postoperatively (0 - +7). The rats were sacrificed on day 20 after surgery, and lung weight and the number of surface pulmonary nodules were measured. Both were significantly decreased in the group of perioperative and postoperative administration of DN-9693. The survival of these rats were furthermore prolonged when Cyclophosphamide (40 mg/kg) was sc injected 3 days after surgical resection. KDH-8 tumor cells (10(4)) were iv inoculated on day 0, and DN-9693 was ip injected at a dose of 150 micrograms twice a day for 7 days on day 0 approximately 7. Rats were sacrificed on day 20, and same studies as above were done. In this artificial pulmonary metastases, the decrease of the number of lung nodules was observed in WKA rat treated with DN-9693. Platelet aggregation induced by KDH-8 tumor cells was inhibited by ADP inhibitor (apyrase, CP/CPK) and thrombin inhibitor (heparin, MD-805); KDH-8 tumor cells induced platelet aggregation by two different mechanisms: ADP-mediated aggregation and thrombin-mediated aggregation. This platelet aggregation by KDH-8 tumor cells was inhibited by DN-9693 with dose-dependency. DN-9693 had no direct anti-tumor effects either in vivo or in vitro. The results indicates that this drug prevents pulmonary metastases by inhibiting platelet aggregation.

We used B 16 melanoma cells both in vitro and in vivo to determine whether Flavone acetic acid (FAA) can increase the cytotoxicity of mitomycin C (MMC) under normothermic and hyperthermic (HT) conditions. The significantly increased cytotoxicity of MMC combined with FAA and HT seems to be mainly related to activation of alkylating species under FAA mediated hypoxic condition.

Rhizoxin is a new macrocyclic lactone isolated from the fungus Rhizopus chinensis. In an attempt to predict the effectiveness of rhizoxin in the treatment of lung cancer, we compared the antitumor activity of rhizoxin with those of cisplatin and etoposide using four small cell lung cancer (SCLC) cell lines, SBC-2, -3, -4, and -7, and two non-small cell lung cancer (NSCLC) cell lines, ABC-1 and EBC-1. The concentrations producing 50% inhibition of the growth of these cell lines (IC50) for each drug were obtained by MTT assay. The IC50 of rhizoxin for these cell lines ranged 0.408 nM to 1.56 nM, which were significant lower than those of cisplatin (660 nM to 16,300 nM) and etoposide (275 nM to 31,300 nM). The ratio of IC50 for the most sensitive cell line, SBC-3, to that for the most resistant cell line was less than 4-fold in rhizoxin, in contrast to more than 20-fold in cisplatin and 100-fold in etoposide. Cross-resistance of rhizoxin to cisplatin and etoposide was investigated using a cisplatin-resistant SCLC subline, SBC-3/CDDP, and an etoposide-resistant SCLC subline, SBC-3/ETP. Of interest, the parent cell line, and the resistant sublines were equally sensitive to rhizoxin, indicating rhizoxin being non-cross-resistant to cisplatin and etoposide. In conclusion, rhizoxin may be beneficial in the salvage chemotherapy of drug-resistant SCLC and non-SCLC.

Twenty-one patients with superficial bladder cancer entered an analysis of single dose (2'R)-4'-O-tetrahydropyranyladriamycin (THP) or adriamycin (ADM) administration. The patients in each group that have been or not have been treated previously with anti-cancer drugs were randomized into two groups, one was given THP and the other ADM. Thirty-mg of THP or ADM dissolved in 30 ml of physiologic saline was instilled into the bladder, and retained for 1 hour. After 1 hour retention of the drugs, tumor tissues and normal mucosas were removed by punch biopsy forceps transurethrally. The tissue concentrations of THP and ADM were estimated by high performance liquid chromatography. The tissue concentrations of THP and ADM in the tumors were significantly greater (p < 0.05) than those in the normal bladder mucosas. The tissue concentration of THP in the tumors were greater than that of ADM. The tissue concentrations of THP and ADM in the tumor of patients who have been treated with anti-cancer drugs previously were less than those of patients who have not. This results demonstrated that prior therapy with anti-cancer drug may cause a resistance for intravesical instillation chemotherapy. However in patients with prior therapy, the tissue concentration of THP in the tumors were greater than that of ADM. Based on these findings, THP has been shown to be were effective as an intravesical instillating agent especially, in cases with prior chemotherapy.

Gastrointestinal toxicities of tegafur (FT) and doxifluridine (DFUR) were compared using mouse intestinal enzymes as the marker. Enzyme activities were decreased during repeated administration of these 5-FU derivatives. When the drugs were administrated once a day, the decrease of enzyme activities were almost equal, but when administrated twice a day. DFUR showed greater decrease. Pharmacokinetical analysis revealed faster catabolism of DFUR than FT. In vitro 5-FU formation by GI extract was much higher from DFUR than FT. These data show a good agreement with the fact that the incidence of diarrhea is much higher in DFUR than FT.

MX2 x HCl is a new morpholino anthracycline derivative with molecular weight 622.07, and highly lipophilic. In the animal experiments, MX2 was found to cross the blood brain barrier after i.v. injection. Its distribution into the brain was increased by intracarotid injection. In the present study, we examined the distribution of MX2 into the cerebrospinal fluid (CSF) after i.v. administration (5 mg/kg) in normal rabbits. Five min after injection, plasma concentration of MX2 reached to the maximum level (4344.5 ng/ml). CSF concentration of MX2 was at the highest level (75.8 ng/ml) 10 min after injection, and thereafter decreased gradually in parallel with plasma concentration. At 5 hrs after injection, CSF concentration became 26.7 ng/ml, AUC half time of elimination, and mean residence time were 3093.8 ng.hr/ml, 4.57 hrs and 5.10 hrs in plasma and 212.3 ng.h/ml, 5.23 hrs and 7.14 hrs in CSF, respectively. These results indicate that MX2 is able to distribute into CSF after i.v. injection, and expected to be a new anticancer drug for brain and leptomeningeal tumors.

Tissue concentration of THP-ADM was analysed after the administration of THP-ADM with or without exposure of high energy underwater shock waves (SW) to rabbit bladder VX2 cancer. THP-ADM was administered intravenously (2 mg/kg) or into the urinary bladder (10 mg/body). After the administration of THP-ADM, SW was exposed (6,000-10,000 shots) to VX2 bladder cancer or normal bladder tissue. One hour later, THP-ADM tissue concentration was measured by high performance liquid chromatography method. In intra-venous group, THP-ADM concentration of cancer tissue was significantly lower (p < 0.02) in SW group than that of non-SW group. In bladder instillation group, THP-ADM concentration of normal bladder tissue was significantly higher (p < 0.02) in SW group than that of non-SW group and the average concentration of cancer tissue was higher about three times in SW group than that of non-SW group.

Although many in vitro chemosensitivity tests for anticancer agents have been reported, no scientific assessment of the optimum exposure time and dose of anticancer drugs for such tests has been established. We assessed the cytotoxicity of 4 anticancer agents (CDDP, CBDCA, ADM, MMC) by analyzing the relationships between the IC50 values and the drug exposure time in a study using PC-14 cells. The clinical AUC (Area Under the Curve) of each drug was compared with the dose giving 50% inhibition of the control level for cell growth (IC50) in a conventional MTT assay (C-MTT). A modified MTT assay, which involved washing out of the drugs and additional incubation (M-MTT) and a HTCA (Human Tumor Clonogenic Assay) was also carried out with PC-9 and PC-14 cells. The results suggested that all of 4 anticancer drugs were AUC-dependent agents. The HTCA was considered to be the assay giving results closest to the doses effective in clinical practice among the 3 assays tested, while the C-MTT gave a much higher AUC than the clinical AUC. It is suggested the reason is that in the C-MTT all the cells are viable at the end of drug exposure. Thus, not only viable cells with the potential of proliferate but also those without this potential are included in the results. On the other hand, viable cells with a proliferative potential are better assessed by the M-MTT, which has an additional incubation time. This study indicated that the C-MTT was unsuitable in vitro chemosensitivity tests for new AUC-dependent drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical usefulness of cytokines in cancer treatment has been described. Cytokines presently used in clinical practice are IFNs, IL-2, and hematopoietic growth factors. IFNs and IL-2 used with an expectation of direct antitumor effect of these cytokines have been proven to be specifically effective against certain types of tumors. Hematopoietic growth factors have been used as the adjuvant drugs in cancer treatment and proven to be effective against neutropenia and associated infections after chemotherapy and bone marrow transplantation. Future development of new cytokines and trials on the combination among cytokines and cytokines with chemotherapeutic agents, will promote the usefulness of cytokines in cancer treatment.