zinostatin and Fibrosarcoma

Immunoconjugate targeting of solid tumors has not been routinely successful because the endo-thelial cells of blood vessels act as a physical barrier against the transport of macromolecules, such as antibodies. In the present study, we attempted to achieve tumor vascular targeting with an anti-tumor tissue endothelium-specific monoclonal antibody (TES-23). TES-23, an IgG1 monoclonal antibody raised against rat KMT-17 fibrosarcoma-derived endothelial cells, was covalently conjugated with neocarzinostatin (NCS) in a previous study. The TES-23-NCS conjugate induced tumor hemorrhagic necrosis, and showed marked anti-tumor effects against rat KMT-17 fibrosarcoma. This result prompted us to investigate whether this approach would be applicable to various other types of solid tumors. One hour after injection of (125)I-labeled TES-23 into BALB / c mice bearing Meth-A fibrosarcoma and Colon 26 adenocarcinoma, the tumor accumulation of TES-23 was greater than that of the control IgG. In the present study, we report the anti-tumor effects of this monoclonal antibody in mice bearing Meth-A fibrosarcoma. Mice treated with the immunoconjugate showed improved survival with no side effects. This result indicates that common antigens may be found in different kinds of tumor endothelial cells, and that TES-23 might recognize these antigens.

Topics: Animals; Antibodies, Monoclonal; Antibody Specificity; Body Weight; Endothelium, Vascular; Female; Fibrosarcoma; Hemorrhage; Immunoglobulin G; Iodine Radioisotopes; Mice; Mice, Inbred BALB C; Necrosis; Radioimmunotherapy; Rats; Tissue Distribution; Zinostatin

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.

Topics: Animals; Antibiotics, Antineoplastic; Carcinogens; Female; Fibrosarcoma; Lymph Nodes; Lymphocytes; Methylcholanthrene; Mice; Mice, Inbred BALB C; Neoplasm Transplantation; Spleen; T-Lymphocyte Subsets; Zinostatin

We reported previously that pretreatment with zinostatin stimalamer (ZSS) eradicated Meth A tumors in BALB/c mice. We herein investigated cellular components of spleen and lymph node cells of Meth A-bearing ZSS-pretreated mice by flow cytometry; the antitumor effector cells by in vivo depletion of T cells, NK cells, or macrophages; and host-mediated antitumor activity associated with ZSS treatment after tumor transplantation. ZSS given on day-3 transiently decreased the number of spleen cells. The percentage of T cells increased, but B cells and macrophages decreased. B cells decreased in inguinal lymph nodes in Meth A-bearing ZSS-pretreated mice, but increased in Meth A-bearing control mice. In vivo depletion experiments using antibodies or carrageenan showed that antitumor effector cells for tumor eradication are Thy1.2+/Lyt2.2+ and that at least a part of them are asialo GM1+. Thy1.2+/Lyt2.2+/asialoGM1- cells are important in generation of the antitumor activity of ZSS; however, L3T4+ T cells are also involved in initiation of tumor eradication. The result of ZSS treatment after tumor transplantation suggests that ZSS might exhibit antitumor activity by augementating host-mediated antitumor resistance, as well as its intrinsic cytocidal activity.

Topics: Animals; Antibodies, Monoclonal; Antigens, Ly; B-Lymphocytes; Female; Fibrosarcoma; Immunophenotyping; Killer Cells, Natural; Lymph Nodes; Lymphocyte Depletion; Macrophages; Maleic Anhydrides; Mice; Mice, Inbred BALB C; Polystyrenes; Spleen; T-Lymphocytes; Thy-1 Antigens; Time Factors; Zinostatin

Zinostatin stimalamer (YM881) is an antitumor agent, chemically synthesized by coupling one molecule of neocarzinostatin (NCS), with 2 molecules of styrene maleic acid half-butylester copolymer. YM881 showed strong cytotoxicity to human (KB, ST4 and others) and mouse (P388, L1210) tumor cell lines and also drug-resistant tumor cell lines. The antitumor effects were observed in murine MM46, colon 26 and other tumor models. The antitumor activity was as effective as NCS or better than NCS at the effective dose ranges.

Topics: Animals; Antineoplastic Agents; Colonic Neoplasms; Drug Screening Assays, Antitumor; Fibrosarcoma; Humans; Leukemia L1210; Leukemia P388; Maleic Anhydrides; Mammary Neoplasms, Experimental; Mice; Mice, Inbred BALB C; Mice, Inbred C3H; Mice, Inbred DBA; Polystyrenes; Stomach Neoplasms; Zinostatin

Neocarzinostatin (NCS) was conjugated with divinyl ether-maleic acid anhydride copolymer (pyran copolymer), and its therapeutic effect was compared with that of NCS. The conjugated NCS (pyran-NCS) with a molecular weight of about 23,000, exhibited in vitro cytotoxic activity against eight cell lines and bone marrow cells that was similar to the cytotoxic activity of NCS on a molar basis. Furthermore, both drugs had similar effects against a multidrug-resistant Chinese hamster ovary cell line (CHR C5) and its parent cell line (AUXB1) in vitro. However, pharmacological analysis showed that pyran-NCS had reduced accumulation in the spleen, and most important was three times less hematotoxic in vivo compared with NCS. Also, pyran-NCS had a 1.7-fold higher 50% lethal dose (LD50). Antitumor activity of pyran-NCS and NCS was tested against two different forms of Meth A tumor. In a solid tumor model, pyran-NCS and NCS suppressed tumor growth at three-fourths of the LD50 to 12.8 and 19.0% of the control tumor as evaluated on day 28, respectively (P less than 0.025). In an ascitic tumor model, the percentage increase in the median life span caused by pyran-NCS and NCS was more than 400 and 150% on day 60, respectively. Pyran-NCS is more effective than NCS because the reduced acute toxicity permits an increased drug dosage.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Fibrosarcoma; Hematopoietic Stem Cells; Humans; Male; Mice; Mice, Inbred A; Mice, Inbred BALB C; Pyran Copolymer; Tumor Cells, Cultured; Zinostatin

The antitumor effects of three biological response modifiers (BRMs; PSK, IFN alpha A/D and OK432) and two chemotherapeutics (Mitomycin C and Neocarzinostatin) in a new experimental mouse model, the "double grafted tumor system," were evaluated. BALB/c mice received simultaneous inoculations of Meth A fibrosarcoma cells on right flank (1 x 10(6) cells) and left flank (2 x 10(5) cells) on day 0, and drugs were given intratumorally into the right-flank tumor on day 3. The growth of the left-flank tumor was the real target for the evaluation of a given drug after 21 days. All tested five agents successfully cured the drug-injected right tumor with a pre-determined optimum dose. In addition, PSK, OK432, IFN alpha A/D and MMC among the five, inhibited the left-flank tumor, whereas no inhibition was observed when treated with NCS. To understand the mechanism by which the antitumor effect of the above four agents is able to influence the growth of tumor on the other side, tumor cells (2 x 10(5) cells) inoculated only into the left flank were treated with drugs given subcutaneously to the right flank (single tumor system). Among the four, MMC exhibited an effect similar to that obtained in the double tumor system, and IFN alpha A/D showed a less pronounced but still definite antitumor effect. However, PSK and OK432 failed to express anti-tumor effect in the single tumor system. These results obtained with PSK, OK432 and IFN alpha A/D suggest that the effect of the drug on the left-tumor may be mediated by certain effector cells, which are specifically induced by injection of the drug, in the right-tumor tissues. When effector cell analysis was conducted with spleen cells obtained after PSK treatment by means of intratumoral adoptive transfer into 3-day Meth A bearing recipients, these cells were shown to be Lyt-1+2(-)-T and L3T4(+)-T cell.

Topics: Animals; Antibodies; Antineoplastic Agents; Cells, Cultured; Complement System Proteins; Fibrosarcoma; Immunization, Passive; Immunologic Factors; Interferon Type I; Male; Mice; Mice, Inbred BALB C; Mitomycin; Mitomycins; Neoplasm Transplantation; Phenotype; Picibanil; Polysaccharides; Spleen; Zinostatin