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Although many agents that interfere with clotting mechanisms have been investigated for their potential to inhibit metastasis, their toxicity has prevented administration of sufficiently high doses to achieve inhibition of metastasis in clinical trials. Nafamostat mesilate (FUT-175), a synthetic serine protease inhibitor, inhibited liver metastasis in a CDF1 mice model with colon 26 adenocarcinoma cells. The apparently dose-dependent inhibitory effect was seen 21 days after all of the doses tested (0.3, 1.0, 3.0 and 10.0 mg/kg for 7 days) but the effect was only statistically significant (P less than 0.01) at the highest dose. The blood concentrations 3 min after dosing were less than 10(-6) M for all of the doses tested. At a concentration of 10(-5) M or less nafamostat mesilate was not cytotoxic towards colon 26 cells in vitro. The results indicate that it may not be difficult to achieve blood nafamostat mesilate concentrations that inhibit metastasis in mouse liver. Possible mechanisms of nafamostat mesilate are inhibition of extravasation and invasion of cancer cells, inactivation of collagenase due to inhibition of plasmin activity and inhibition of the formation of the cancer cell thrombus, and arrest in the capillaries through inhibition of thrombin activity. These preliminary results suggest that peri-operative administration of nafamostat mesilate may prevent metastasis into the liver after surgery for gastrointestinal malignancies.

We investigated the antitumor activities of 5-fluorouracil (5-FU), 5'-deoxy-5-fluorouridine (5'-DFUR), 1-hexylcarbamoyl-5-fluorouracil (HCFU) and 1-(tetrahydro-2-furanyl)-5-fluorouracil (FT-207) in combination with hyperthermia in vitro. The antitumor effect of 5-FU (10(-4) M) was slightly enhanced by combination with hyperthermia (42 degrees C) for 2h, and the effect was determined to be additive. Synergistic enhancement of antitumor activity was obtained by the concurrent use of hyperthermia (42 degrees C, 2h) and 5'-DFUR (10(-4) M) or HCFU (10(-5) M). However, the antitumor effect of FT-207 (10(-4) M) in combination with hyperthermia was comparable that of hyperthermia alone. The synergistic enhancement of antitumor activity was not obtained for all drugs when the cells were preheated at 42 degrees C for 2h. On the other hand, when cells were pretreated with drugs before heat exposure, weak interactions were obtained after 5-FU and 5'-DFUR treatment, and a synergistic interaction was obtained after HCFU treatment. It is speculated that the metabolites of 5'-DFUR and HCFU enhance the cytotoxicity of 5-FU, or might change the threshold concentration for a cytotoxic effect of 5-FU in cancer cells.

The histopathologic changes following chemotherapy treatment of fresh human tumors implanted under the renal capsule of normal immunocompetent mice were evaluated. On the basis of the histopathologic profile of the xenografts, four parameters were recognized: (1) cancer area (C), (2) necrosis area (N) (each measured by image analysis), (3) pathologic effect of cancer cells (P) (assessed histopathologically), and (4) number of mitoses (M) (counted microscopically), and were scored in a semiquantitative fashion from 0 to 2 or 4. The drug sensitivity (S) was scored using the following formula: S = C + P + M - N; this score varied from -4 to 10. Histopathologic changes represent a sensitive indicator of the response of implanted human tumors under the renal capsule to anticancer drugs. Availability and correct interpretation of the post-treatment histopathologic picture is of importance in selecting the proper combination treatment which would maximize tumor response.

This study was conducted to assess the enhanced antitumor effects of natural human tumor necrosis factor alpha (nHuTNF-alpha) and natural human interferon alpha or gamma (nHuIFN-alpha or -gamma), in combination, on ten human cancer cell lines. The cell lines tested were colon cancer (RPMI4788), lung cancer (PC10), gastric cancer (MKN-1 and MKN-28), nasopharyngeal cancer (KB), leukemia (K562), lymphoma (Daudi), Liver cancer (H-7) and breast cancer (ZR-75-30 and ZR-75-1). A mixture of nHuTNF-alpha and nHuIFN-alpha (1:1, by unit) showed cytotoxic effects on nHuTNF-alpha resistant cell lines such as RPMI4788, KB and Daudi or nHuIFN-alpha resistant cell lines such as KB, and ZR-75-1, as well as on nHuTNF-alpha or nHuIFN-alpha sensitive cells. A synergistic antitumor effect occurred in four cell lines (RPMI4788, PC10, Daudi and ZR-75-1) treated with a combination of nHuTNF-alpha and nHuIFN-alpha. Also, a combined treatment with nHuTNF-alpha and nHuIFN-gamma (1:1/100, by unit) showed cytotoxic effects on nHuTNF-alpha or nHuIFN-gamma resistant cell lines such as MKN-1, MKN-28, Daudi, H-7 and ZR-75-1. A synergistic antitumor effect occurred in eight cell lines (RPMI4788, PC10, MKN-1, MKN-28, KB, Daudi, H-7 and ZR-75-1). Thus, the combined treatment with nHuTNF-alpha and nHuIFN-alpha or -gamma expanded the spectrum of sensitive cells. These results indicate that the combined use of nHuTNF and nHuIFN may provide a certain approach to cancer treatment.

Fresh surgical explants of solid tumors obtained from 50 patients were tested against six chemotherapeutic agents in the in vivo subrenal capsule assay. Control growth adequate to meet evaluable assay criteria was obtained in 36 of 50 tumors (72.0%). With activity criteria set at current drug screening levels as a change in modifidd PAPAN score in less than or equal to -2.0 for the SRC assay, 36.1% of the human tumors evaluable and 11.6% of drugs tested were sensitive, respectively. Our research reveals that gastric cancers respond to drugs about 2.5-fold higher than colorectal cancers. Comparisons were made of the drug sensitivity in terms of histologic differentiation, and it was strongly suggested that the sensitivity of the poorly differentiated type was higher than that of well or moderately differentiated type.

When the plasma membrane capacity to maintain an ionic gradient is correlated with the cell viability, the anticancer drug-induced-cation (K+, Ca2+) mobilization, an early event associated with cell death, might be used as a rapid in vitro drug sensitivity test. A cyanine dye, dis-C3-5, was used to determine the membrane potential (Em), which was calculated as the following formula; Em = -RT/F In ([K+] in/[K+] out) in cancer cell lines. The change in cytoplasmic free calcium ion ([Ca2+]i) mobilization induced by the drugs was measured by fluorescent dye Fura2-AM. The results suggest that the sensitive drug, which showed greater than or equal to 50% inhibition of succinate dehydrogenase activity in SDI test, induced greater than or equal to 30% fall of membrane potential after 2 hour exposure to the drugs and also induced [Ca2+]i mobilization. On the other hand, the resistant drug showed no change of Em and [Ca2+]i.

We investigated the antitumor effect of purified natural human tumor necrosis factor-beta (nHuTNF-beta) produced by human acute lymphoblastic leukemia BALL-1 cells stimulated with HVJ on pulmonary metastatic tumors of Lewis lung carcinoma (3LL) transplanted into BDF1 mice. nHuTNF-beta showed antiproliferative effects on metastatic tumors in a dose-dependent manner when administered daily for 10 days by the intravenous route. Histological examination of the tumors treated with nHuTNF-beta revealed that the tumor size and number of metastases were much reduced. Lytic cellular changes, including cytoplasmic vacuolation, loosening of the intercellular junction and both cytoplasmic and nuclear swelling, were found, but tumor necrosis was not. These findings indicate a therapeutic effect of Grade IIa according to the histological criteria of Shimosato and Ohboshi. In addition, synergistic augmentation of the antiproliferative effects of nHuTNF-beta by natural murine interferon-alpha/beta (nMu-IFN-alpha/beta) or recombinant murine interferon-gamma (rMuIFN-gamma) was recognized by median effect plot analysis. The results suggested that nHuTNF-beta may well deserve clinical trial as a new immunotherapeutical agent for human cancer.