Chemotherapy for bladder cancer with neocarzinostatin: evaluation of systemic administration

Changes in cellular composition induced by neocarzinostatin pretreatment in Meth A-bearing mice and the responsible antitumor effector cells

We previously reported that tumor eradication was induced by a single injection of neocarzinostatin (NCS) between 1 day and 4 weeks before Meth A transplantation in Balb/c mice via augmenting host-mediated antitumor activity. In order to elucidate the mechanism of this tumor eradication, the cellular components of spleen and regional lymph nodes, tumor infiltrating cells and antitumor effector cells were investigated. Pretreatment with NCS on day -3 caused an increase in the percentage of T-cell subsets, a decrease in the percentage of B-cells, Mac-1+ cells and asialo GM1+ cells and a decrease of the total cell number in the spleen. These changes were observed before but not during the period of tumor regression and were also observed in non-transplanted mice with NCS treatment. In the lymph nodes, while B-cells increased on Meth A transplantation, this was suppressed by NCS pretreatment. Although histological examination of tumor nodules showed the presence of only a few host immune cells in the tumor tissue, the area of necrosis was already extensive on day 7 and expanded thereafter. In vivo depletion of whole T-cells, T-cell subsets or asialo GM1+ cells by antibody treatment suggests that the antitumor effector cells in tumor eradication were Thy1,2+/Lyt2+, and at least some of which also express asialo GM1 antigen and that L3T4+ T-cells were also involved in tumor eradication.

Specific cytotoxic effect of neocarzinostatin conjugated to monoclonal antibody A7 on human pancreatic carcinoma

The anti-cancer drug neocarzinostatin (NCS) was bound covalently to the monoclonal antibody A7 to form the conjugate A7-NCS. This antibody was produced by fusing the spleen cells of a mouse immunized against human colonic carcinoma with murine myeloma cells and reacts with a high percentage of human pancreatic carcinoma cell lines and with no normal human pancreas tissue by immunoperoxidase staining. The cytotoxic effect of A7-NCS was tested by measuring the inhibition of 3H-thymidine incorporation into human pancreatic carcinoma cells. The A7-NCS was approximately 2.7 times as effective as free NCS against human pancreatic carcinoma cells which reacted with the monoclonal antibody A7. A7-NCS had almost the same cytotoxicity a free NCS on human pancreatic carcinoma cells which did not react with the monoclonal antibody A7. A7-NCS appeared to be potentially useful as a conjugate for immunotargeting chemotherapy against pancreatic carcinoma.

Differential neutralizing effect of tiopronin on the toxicity of neocarzinostatin and SMANCS: a new rescue cancer chemotherapy

The toxic effect and antitumor activity of neocarzinostatin (NCS) and SMANCS [copoly(styrenemaleic acid)-conjugated NCS] were greatly affected by N-(2-mercaptopropionyl)-glycine [tiopronin] both in vitro and in vivo, in cultured HeLa cells and RL male 1 tumor-bearing mice. The cytotoxicity of NCS and SMANCS against HeLa cells was remarkably reduced by the addition of tiopronin during drug treatment. Interestingly, the neutralizing effect of tiopronin on the toxicity of SMANCS was greater than that in the case of NCS. In the continuous presence of 10 mM tiopronin during a 1 h drug treatment, the 50% cell-killing doses of NCS and SMANCS were increased 72 and 208 times as compared to those without tiopronin, respectively, whereas tiopronin itself has no cytotoxicity to HeLa cells up to 100 mM. Furthermore, more effective reduction of the lethal toxicity of SMANCS was observed by the intraperitoneal (ip) administration of tiopronin after ip injection of a lethal dose of SMANCS as compared to the same protocol in the case of NCS in mice. Therapeutic studies on RL male 1 tumor-bearing mice revealed that delayed (time lag) ip administration of tiopronin after high-dose SMANCS administration ip was much superior to the combination of NCS with tiopronin, or SMANCS alone. In this time-lag combination chemotherapy of SMANCS with tiopronin, 60% of treated mice survived more than 60 days after tumor inoculation, while all the untreated control mice died within 20 days.

Advanced transitional cell bladder cancer: a treatable disease

Although metastatic bladder cancer is difficult to treat effectively, chemotherapy combinations and schedules have emerged recently that can result in long-lasting complete responses in some patients. Response rates, response durations, and survival patterns of the entire patient population are, however, unsatisfactory. Whereas survival times of these patients following therapy with cisplatin alone or in combination with other drugs are not significantly different, complete response rates are higher and disease-free survival is longer when combinations are used. Higher dosages are associated with better response rates but also with substantial toxicity. Extensive local pretreatment or prior systemic chemotherapy reduces the likelihood of clinically meaningful disease response. Several adjuvant studies have demonstrated an advantage in length of disease-free survival for chemotherapy-treated patients when compared to those who are observed following operation. Metastatic transitional cell bladder cancer is a chemotherapeutically treatable malignancy. Locally advanced disease may be most effectively treated by aggressive surgery followed by cisplatin-based combination chemotherapy. The highest response rates and longest disease-free survivals are uniformly associated with aggressive and prolonged multidrug therapy.