Murine Bladder Tumor Model Research Articles

Adenovirus-mediated suicide-gene therapy in an orthotopic murine bladder tumor model.

Patients with high-grade transitional-cell carcinoma (TCC) of the bladder frequently experience recurrence and progress and have a low response rate to chemotherapy in metastatic TCC. In this study, we evaluated the feasibility and long-term efficacy of suicide-gene therapy using adenovirus (Ad)-mediated herpes simplex virus thymidine kinase gene (HSV-TK) and prodrug ganciclovir (GCV) as a potential therapeutic approach in murine-orthotopic models of TCC. A replication defective adenoviral vectors containing toxic HSV-TK gene under the transcriptional control of RSV (Rous sarcoma virus) promoter (Ad-RSV-TK) was used. Orthotopic bladder TCC was established with 1 x 106 murine (MBT-2) TCC cells in syngenic C3H/He female mice. Intratumoral injection of Ad-RSV-TK in combination with GCV (20 mg/kg body weight/day i.p. b.i.d. x 7 days) was administered in vivo for the determination of treatment efficacy and long-term host survival in separate controlled experiments. In vivo experiments demonstrated greater than three-fold reductions in MBT-2 tumor growth for the animals treated with Ad-RSV-TK (5 x 108 plaque forming units (pfu)/GCV therapy (P < 0.01)). Central tumor necrosis and apoptosis were revealed by histomorphology and immunohistochemistry compared with other control animals (non-treated, GCV alone, Ad-RSV-TK alone). Direct intratumoral injection with Ad-RSV-TK/GCV also resulted in significantly improved survival over the control groups in separated experiment (log-rank test, P < 0.05). Suicide-gene therapy using Ad-RSV-TK/GCV provides an effective therapy in an experimental murine orthotopic bladder cancer by significantly inhibiting tumor growth and improving long-term host survival.

Immunological protection induced by bacillus Calmette-Guérin treatment in a murine bladder tumor model.

It has been previously reported that MBT-2 tumor growth is completely inhibited when mice are inoculated with bacillus Calmette-Guérin (BCG). In this study it was examined whether or not vaccination with a mixture of BCG and MBT-2 cells also induces immunological protection against murine bladder tumors. Seven hundred thousand MBT-2 cells and 1 mg of BCG (Tokyo 172 strain) per mouse were injected subcutaneously into female C3H/HeN mice. Four and eight weeks after vaccination with this mixture, animals were reinoculated with MBT-2 cells alone or MBT-2 cells cocultured with BCG. Animals vaccinated with a mixture of BCG and MBT-2 cells showed MBT-2 tumor growth but completely rejected the MBT-2 cells cocultured with BCG. MBT-2 cells cocultured with BCG developed into tumors when they were inoculated into the control animals. Splenocytes prepared from vaccinated animals showed specific cytocidal activity against MBT-2 cells precultured with BCG. The results suggest that a mixture of BCG and MBT-2 cells induces antitumor immunological protection against BCG- or MBT-2-associated antigens presented on MBT-2 cells precultured with BCG.

INHIBITION OF BLADDER CARCINOMA CELL ADHESION BY OLIGOPEPTIDE COMBINATIONS IN VITRO AND IN VIVO

A presumed reason for the high recurrence rate of superficial bladder cancer after transurethral tumor resection is the reimplantation of tumor cells. Because tumor cell adhesion to the extracellular matrix is mediated by integrin molecules, we tested specific integrin receptor blocking oligopeptides to prevent this mechanism. An in vitro cell adherence assay with various bladder cancer cell lines and extracellular matrices, including fibronectin, collagen type I, laminin and combinations, was used to analyze the inhibition of tumor cell adhesion by the matrix specific oligopeptides GRGDS, DGEA and EILDV. In therapeutic in vivo experiments the orthotopic murine bladder tumor model MB49 was used. The ability of oligopeptides to interfere with tumor cell adhesion and consecutive tumor outgrowth was evaluated and compared with that of nonspecific peptides, commercially available irrigation fluid and single dose epirubicin chemotherapy. In vitro fibronectin specific oligopeptides showed a concentration dependent inhibition of tumor cell adherence to fibronectin, whereas adhesion to laminin, collagen and combined matrices was not inhibited. In contrast, combinations of integrin receptor blocking oligopeptides were highly active. In vivo local tumor take was not affected by irrigation fluid, nonspecific peptides or monospecific oligopeptides alone, whereas the combination of the 3 oligopeptides effectively inhibited tumor outgrowth. Combining oligopeptides with various specificities significantly inhibited tumor cell adhesion and tumor outgrowth. Application of this principle in a clinical setting may be an effective method for reducing the recurrence rate of superficial bladder cancer.

CURCUMIN PREVENTS INTRAVESICAL TUMOR IMPLANTATION OF THE MBT-2 TUMOR CELL LINE IN C3H MICE

The development of an effective nontoxic intravesical agent that may be used immediately after bladder tumor resection to prevent the implantation of tumor cells would be a significant clinical advancement. We report the cytotoxic effects of curcumin on bladder tumor cell lines as well as its effects on the intravesical implantation of tumor cells in C3H mice. UMUC human and MBT-2 mouse bladder cancer lines were incubated with 0 to 100 microM. curcumin in dimethyl sulfoxide for 30 minutes and cell viability was determined by clonal assay. Additional culture dishes were incubated with curcumin and processed for electron microscopy. Using the C3H mice and the MBT2 tumor lines the effects of intravesical curcumin on tumor implantation after bladder injury was studied. The 10 group 1 mice served as nontreatment controls. In the 18 group 2 mice 30 minutes after tumor cell implantation 100 microM. curcumin in 0.1% dimethyl sulfoxide were instilled intravesically for 30 minutes. The 15 group 3 mice served as treatment controls with 0.1% dimethyl sulfoxide or culture medium instilled intravesically for 30 minutes. Animals were sacrificed 7 to 10 days after treatment and the bladder was subjected to histological analysis for tumor. At the 100 microM. dose curcumin was completely lethal to the 2 cell lines on clonal growth assay. Electron microscopy revealed apoptotic bodies after curcumin administration. The tumor implantation rate was 16.7% (3 of 18 mice) in curcumin treated bladders and 73% (11 of 15) in the vehicle control group. At the 100 microm. concentration curcumin is a potent cytotoxic agent against the MBT and UMUC bladder tumor cell lines. In addition, curcumin effectively inhibits tumor implantation and growth in this murine bladder tumor model.

Intravesical liposome-mediated interleukin-2 gene therapy in orthotopic murine bladder cancer model.

Using a novel orthotopic MBT-2 murine bladder tumor model, we evaluated the feasibility of intravesical gene therapy utilizing a cationic liposome, DMRIE/DOPE. Superficial bladder tumors were consistently established by intravesical instillation of 5x10(5) MBT-2 cells in syngeneic C3H female mice. In situ gene transfer to bladder tumors was accomplished via intravesical instillation of plasmid DNA/DMRIE/DOPE lipoplex. Beta-Galactosidase (beta-gal) gene expression was preferentially evident in bladder tumors and was present for at least 7 days after a single 30 min in situ transfection. Murine interleukin-2 (IL-2) gene was used for treatment of 3-day-old pre-established bladder tumors. Forty percent of animals treated with IL-2 gene were completely free of tumors by 60 days following the initial tumor implantation, while all control groups treated with beta-gal gene died. Those animals initially cured of pre-established tumors were completely resistant to a subsequent tumor re-challenge and their splenocyte-derived cytotoxic T lymphocytes were shown to be specific to MBT-2 cells, indicating that immunological memory against MBT-2 tumors was elicited by the treatment. These results demonstrate the possibility of an effective clinical application of this in situ intravesical IL-2 gene delivery system to high-risk superficial bladder tumors, obviating a need for tumor procurement and ex vivo gene transfer.

EFFECTS OF ACETYLIC SALICYLIC ACID AND PENTOXIFYLLINE ON THE EFFICACY OF INTRAVESICAL BCG THERAPY IN ORTHOTOPIC MURINE BLADDER CANCER (MB49)

Intravesical immunotherapy with bacillus Calmette-Guerin (BCG), which has become the gold standard in the adjuvant treatment of superficial bladder cancer, is hampered by local side effects. Anti-inflammatory drugs may be helpful, but as an undesired side effect, therapeutic efficacy of BCG might be impaired. Therefore, we investigated the effects of anti-inflammatory drugs on the efficacy of intravesical BCG in an animal model. Syngenic tumor cells were implanted into the bladders of 75 mice according to our modification of the method. Mice were randomized to 5 groups with 15 animals each and treated with phosphate buffered saline (PBS), group 1; BCG, group 2; BCG + acetylic salicylic acid (ASA), group 3; BCG + pentoxifylline (POF), group 4; autoclaved BCG (aBCG), group 5. Intravesical instillation of 1.35 mg. BCG was initiated one day after tumor inoculation and repeated in weekly intervals for 4 instillations altogether. ASA and POF in doses of 200 mg./kg. and 150 mg./kg., respectively, were given continuously with the drinking water starting at the first instillation. Autoclaved BCG served as control for the importance of viability and was given at the same dose as viable BCG. Mice were monitored for survival, gross hematuria and body weight and after 28 days evaluated for bladder weight and tumor occurrence. Autoclaved BCG and PBS had no effect on tumor growth, whereas animals treated with viable BCG alone and in combination with POF and ASA, respectively, showed a significant reduction in bladder weight: PBS, 248 mg.; BCG, 140 mg. (p = 0.0009); BCG + ASA, 123 mg. (p = 0.0001); BCG + POF, 145 mg. (p = 0.0004); autoclaved BCG, 283 mg. (p = 0.21). Mice treated with BCG, BCG + ASA and BCG + POF showed a significantly higher proportion of survival until day 28 as compared to PBS alone. Autoclaved BCG had no therapeutic efficacy (Kaplan-Meier method/log rank test: BCG, p = 0.0053; BCG + ASA, p = 0.0044; BCG + POF, p = 0.0027; aBCG, p = 0.33). No significant differences among the 3 groups treated with viable BCG, with or without anti-inflammatory drugs, regarding bladder weight and survival were detectable. The efficacy of BCG therapy in murine orthotopic bladder cancer is dependent on BCG viability and is not compromised by ASA or POF. Clinical trials to evaluate the efficacy of routine ASA or POF to reduce BCG side effects in patients, using self-assessment criteria, should be initiated.

Regression of tumors in mice vaccinated with professional antigen-presenting cells pulsed with tumor extracts.

Vaccination with tumor extracts circumvents the need to identify specific tumor rejection antigens and extends the use of active immunotherapy to the vast majority of cancers, in which specific tumor antigens have not yet been identified. In this study we examined the efficacy of tumor vaccines comprised of unfractionated tumor material presented by professional antigen-presenting cells (APC): dendritic cells (DC) or macrophages (M phi). To enhance the relevance of these studies for human patients we used 2 poorly immunogenic murine tumor models and evaluated the effectiveness of the vaccination protocols in tumor-bearing animals. APC (in particular DC) pulsed with unfractionated extracts from these "poorly immunogenic" tumors were highly effective in eliciting tumor-specific cytotoxic T lymphocytes. A measurable CTL response could be detected after even a single immunization with tumor extract-pulsed DC. DC or M phi pulsed with tumor extract were also effective vaccines in tumor-bearing animals. In the murine bladder tumor (MBT-2) model a modest extension of survival and 40% cure rate was seen in the animal groups immunized with DC or M phi pulsed with MBT-2 tumor extract. DC or M phi pulsed with B16/F10.9 tumor extract were also remarkably effective in the B16 melanoma lung metastasis model, as shown by the observation that treatment with APC caused a significant reduction in lung metastases. Cumulatively, the CTL and immunotherapy data from the two murine tumor systems suggest that APC (in particular DC) pulsed with unfractionated cell extracts as a source of tumor antigen may be equally or more effective than genetically modified tumor vaccines.

Modulation of Antitumor Immunity of Tumor-Bearing Mice with Low-Dose Cyclophosphamide

As a tumor progressively grows, the tumor-bearing host usually is under a tumor-mediated immune suppression status. Although surgical resection of the tumor may immediately eliminate most tumor-induced detrimental influences, perioperatively the antitumor immunity of the host remains temporarily suppressed. The major purpose of this study is to investigate the modulation effect of low-dose cyclophosphamide (CY) on the antitumor immunity of tumor-bearing mice (TBM). Using the C3H/He-MBT-2 murine bladder tumor model, we demonstrate that low-dose CY (100 mg/kg) intraperitoneal injection 2 days before tumor resection can significantly enhance the specific antitumor immunity of the TBM. It consequently suppresses the outgrowth of perioperative rechallenged tumor cells and improves the survival of the animals. Phenotypic analysis of cellular subset of spleen by flow cytometry revealed that low-dose CY, when given to both naive and tumor-bearing mice, causes significant reduction of both absolute number and percentage of cells with CD4−CD8−subset in the spleens of TBM. As a result of a parallel increase in the percentage of both CD4+CD8−and CD4−CD8+subsets, the CD4+/CD8+ratio remains unchanged. However, after short-termin vitroculture with IL-2 the percentage of the CD4−CD8−subset and CD4+/CD8+ratio markedly decreased because of the relatively predominant proliferation of the CD4−CD8+subset. Evidence fromin vitrocytotoxicity assays on panel tumor cells and phenotypic analysis revealed that this enhancement of host antitumor immunity, following low-dose CY pretreatment, may be due to augmenting the activity of NK, LAK, and CD11b+myeloid/macrophages in addition to cytotoxic T lymphocytes.

Immunotherapy with Keyhole Limpet Hemocyanin: Efficacy and Safety in the MB-49 Intravesical Murine Bladder Tumor Model

The antitumor activity and potential toxicity of a clinical-grade keyhole limpet hemocyanin preparation (KLH▪-ImmuneActivator; KLH-IA) were determined in the MB-49 intravesical murine bladder tumor model. Mice were immunized subcutaneously with KLH-IA two weeks prior to intravesical implantation of MB-49 tumor cells. Treatment consisted of intravesical KLH-IA (10 or 100μg.) 1, 4, 7, 14 and 21 days after implantation. Control animals either were not immunized prior to tumor implantation and KLH-IA treatment, or were immunized with KLH-IA and treated with the vehicle. By 4 weeks after implantation tumor outgrowth in the treated groups was significantly decreased (p < 0.01, Fisher’s Exact) relative to the control groups. Prior subcutaneous immunization was required to elicit antitumor activity of KLH-IA; thus, the mechanism of action is immune-mediated and not due to spurious interference with tumor implantation by intravesical instillations. Animals treated with a dissociated form of KLH exhibited decreased tumor outgrowth approaching, but not attaining, significance (p < 0.09, Fisher’s Exact). A separate toxicity study in which KLH-IA was given subcutaneously (4mg./kg.), intraperitoneally (40mg./kg.), or intravesically (40mg./kg.) disclosed no significant gross or histopathologic abnormalities except for mild-to-moderate papillary hyperplasia in all catheterized animals. These results establish the efficacy and safety of KLH-IA in mice and suggest that clinical trials for intravesical treatment of superficial bladder cancer may be warranted.

Sequential Immunocytological Evaluation of Murine Transitional Cell Carcinoma During Intralesional Bacillus Calmette-Guerin and Interleukin-2 Immunotherapy

The antitumor effect of intralesionally administered recombinant interleukin-2 was highly effective (90% complete response) in murine bladder cancer. We postulated that interleukin-2 may be integral to the Bacillus Calmette-Guerin-induced antitumor response in human bladder cancer. Flow cytometric evaluation of the tumor infiltrates was compared before and after intralesional treatment of an established, untreated murine bladder tumor model with recombinant interleukin-2, Bacillus Calmette-Guerin or saline. Large increases in the number of tumor infiltrating immune cells occurred between the day of randomization and the second day (one day after the first treatment) in all three groups. However, since tumor volume was reduced by treatment, the ratios of the immune cells to tumor volume was increased. The ratios of Thelper, Tcytotoxic/suppressor cells, macrophages, and natural killer cells to tumor volume were 1.5 to 3.4 times higher in the interleukin-2 and Bacillus Calmette-Guerin groups in comparison to the saline group. The ratio of Thelper/Tcytotoxic/suppressor cells however, remained approximately the same despite treatment. Over the next 22 days all subpopulations of tumor infiltrating immune cells decreased in number and frequency to less than measurable levels. The similar modulation of infiltrating immune cell subpopulations by Bacillus Calmette-Guerin and interleukin-2 may indicate that the production of interleukin-2 is part of the tumor modulating mechanism of Bacillus Calmette-Guerin.

Effects of Photodynamic Therapy in Combination with Intravesical Drugs in a Murine Bladder Tumor Model

This study was designed to evaluate the interaction of photodynamic therapy (PDT) and intravesical drugs (thiotepa, adriamycin, mitomycin C and BCG) in a murine transitional cell carcinoma (MBT-2) model. C3H/He mice with implanted MBT-2 flank tumors were treated with either thiotepa (TT), adriamycin (ADM), mitomycin C, Bacillus Calmette-Guerin (BCG), photodynamic therapy (PDT) or a combination of the drug and PDT. The MBT-2 tumor showed sensitivity to adriamycin, MMC or PDT compared to control. PDT combined with either adriamycin, MMC or BCG, produced a greater retardation in the growth of the MBT-2 tumor than monotherapy with adriamycin, MMC, BCG or PDT.PDT combined with the anticancer agents currently used in intravesical therapy for bladder cancer is well tolerated. The combination of PDT and intravesical drugs may enhance the tumoricidal effect of either treatment used alone.

Experimental and clinical study of intravesical BCG therapy. The role in the prevention of recurrence of superficial bladder tumor

The effects of Tokyo strain bacillus Calmette-Guerin (BCG), which is available in Japan for treatment, were studied in an experimental murine bladder tumor (MBT-2) model prior to clinical study for treatment of superficial bladder tumor. The results were as follows: Tokyo-strain BCG is more effective on the local injection around the tumor than on systemic administration. BCG therapy is more effective at earlier time of small tumor burden. BCG also has a prophylactic effect against the tumor growth. Clinical trial of intravesical instillation of BCG was performed on patients with superficial bladder tumor for prophylaxis of tumor recurrence after transurethral resection of the tumor. In patients of 145 primary cases, the tumor recurrence rate after BCG therapy was estimated, comparing with that of historical control in our department. The historical control groups are consisted of 50 patients who were treated by some intravesical chemotherapy after TUR and 38 patients, who were treated by TUR alone. The tumor recurrence rate in BCG group was significantly lower than that in both control groups. No relationship between PPD responsiveness and the tumor recurrence rate could be detected. On the other hand, in the patients of 36 recurrent cases, evaluation was performed by the tumor recurrence rate comparing with those during the two years prior to BCG therapy. The results demonstrated a statistically significant decrease in recurrent tumor following BCG therapy. Although most of the adverse effects in this study such as bladder irritability, flu-like syndrome and macroscopic hematuria were minimal and tolerable. There were no significant side effects or serious complications attributable to BCG therapy in this series. These results indicate that intravesical Tokyo strain BCG instillation provide prophylactic effects against recurrence of superficial bladder cancer.

Fibronectin-mediated Calmette-Guerin bacillus attachment to murine bladder mucosa. Requirement for the expression of an antitumor response.

Adjuvant intravesical Calmette-Guerin bacillus (BCG) is an effective treatment for superficial bladder cancer. The mechanisms by which BCG mediates antitumor activity are not known. We investigated the initial interaction of BCG with the bladder mucosa to determine whether binding was essential for the development of antitumor activity. Herein, we show that bladder urothelial disruption induced by acrolein, adriamycin, or electrocautery resulted in BCG binding in areas of urothelial damage. Binding induced by each method was inhibited by anti-fibronectin (FN) antibodies but not by antibodies to the basement membrane component laminin. Intravesical BCG binding also was inhibited by pretreating BCG with soluble FN. Inhibition of intravesical FN-mediated BCG attachment prevented immunization via the intravesical route. Moreover, the expression of both delayed hypersensitivity in the bladder of BCG-immunized mice and antitumor activity was inhibited by blocking FN-mediated intravesical BCG attachment. These data suggest that intralumenal attachment of BCG appears to be mediated by FN. Moreover, these data suggest that intravesical FN mediated attachment of BCG is a requisite step in BCG-mediated antitumor activity in the murine bladder tumor model.

In Vitro and in Vivo Activity of Two Second Generation Platinum Analogs in Murine Bladder Cancer

The activity of cis-diamminedichloroplatinum(II) was compared to two second generation platinum analogs, cis-diammine-1,1-cyclobutane dicarboxylate platinum(II) and cis-dichloro-transdihydroxybisisopropylamine platinum(IV) in the N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide-induced murine bladder tumor model and a tumor colony assay. Murine drug testing revealed that all three drugs were active against the MBT-2 tumor line, although cis-diamminedichloroplatinum(II) was more active than its analogs. All drugs produced enhanced inhibition of clonal growth with increasing drug exposure times. Cis-diamminedichloroplatinum(II) was more active against MBT-2 cells in the plateau growth phase versus the log growth phase after a one hour drug exposure. Similar differential activity depending upon the proliferative state of MBT-2 was not seen with the two platinum analogs. These two platinum analogs have somewhat less activity in vivo and in vitro than cis-diamminedichloroplatinum(II) and would be predicted to be less effective clinically in human bladder cancer than the parent compound

Effect of concentration and time of drug exposure on clonal growth of murine bladder cancer

The use of a tumor colony assay was evaluated for its ability to predict anticancer drug response in an N[4-(5-nitro-2 furyl)-2-thiazolyl] formamide mouse bladder tumor model. One-hour and continuous drug exposure were compared to determine what effect altering drug concentration and time of exposure would have on the predictability of t he tumor colony assay in the murine model. Ten anticancer drugs were tested in the murine model, and tumor cells removed from control mice were used for in vitro drug testing. One-hour and continuous drug exposure (using the one-hour drug level) were performed simultaneously and the in vitro and in vivo data compared. Using one-hour drug incubation in the tumor colony assay resulted in a true positive predictive rate of 54 per cent and a true negative predictive rate of 70 per cent. Continuousdrug incubation overestimated drug sensitivity resulting in a drop in the predictability of the tumor colony assay. We conclude that using one-hour drug exposure the tumor colony assay is predictive of chemotherapeutic drug response in this murine bladder tumor model.

Enhancement of High Intensity Iodine-125 Brachytherapy by Cis-Platinum in a Murine Bladder Tumor Model

The interaction of cis-platinum chemotherapy and high-intensity Iodine-125 brachytherapy was studied in C3H/He mice with MBT-2 tumors growing in the thigh. Brachytherapy was delivered by 3 Iodine-125 seeds of 10 mCi each implanted into the tumor. Ninety-six animals were randomly divided into 8 groups of 12 animals each. Each group was given either no treatment (control), cis-platinum alone or brachytherapy of 20, 40 or 50 Gy either alone or combined with cis-platinum. Cis-platinum 3mg. per kg. was given every 5 days for 3 doses.The addition of cis-platinum enhanced the effects of Iodine-125 brachytherapy as shown by the end-points of tumor regrowth delay, local tumor control and median survival times. The sensitization enhancement ratio ranged from 1.2 to 1.9. Further experiments are to be conducted to study the normal tissue effect, therapeutic gain factor, effects of altering the time of administration of cis-platinum and the clinical use of high-intensity Iodine-125 for removable brachytherapy.

Effect of combination chemotherapy on murine bladder cancer.

A murine bladder tumor model was evaluated for tumor growth retardation while receiving combination chemotherapy, either 40 mg/m2 methotrexate and 35 mg/m2 cis-platinum or 500 mg/m2 cytoxan and 35 mg/m2 cis-platinum at 3-week intervals. Tumor growth was observed in the control and treated groups. A significant decrease (p less than 0.001) in tumor growth and lung metastasis was noted in the cytoxan and cis-platinum group. Although the 40 mg/m2 group treated with methotrexate and 35 mg/m2 cis-platinum showed a decrease in tumor growth, it was not significant (p greater than 0.1), and lung metastasis was greater than in the control group. Cis-platinum with cytoxan was clearly effective in retarding tumor growth and metastatic spread.

The use of a tumor colony assay in predicting chemotherapeutic drug response in murine bladder cancer.

A tumor colony assay (TCA) was evaluated for its ability to predict anticancer drug responses in an N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide (FANFT)-induced murine bladder tumor (MBT) model. Ten anticancer drugs were evaluated in vivo and in vitro using four MBT cell lines (40 drug responses). Using the optimum criteria for drug response, the TCA accurately predicted drug responses in the murine model 65% of the time with a true-positive predictive rate of 54% and a true-negative predictive rate of 70%. Drug testing tumor cells immediately on removal from the mouse resulted in a true-positive predictive rate of 77% and a true-negative predictive rate of 100%. The authors conclude that the TCA can predict response to chemotherapy in the MBT model and may be useful in screening investigation compounds for the subsequent evaluation in this murine bladder tumor model.

Chemoimmunoprophylaxis of an Experimental Bladder Cancer with Retinoids and Bacillus Calmette Guérin

The prophylactic effect of 2 retinoids (Ro 4-3780 and Ro 10-9359), either alone or in combination with Bacillus Calmette Guérin (BCG), was studied in an experimental murine bladder tumor model. The incidence of tumor takes in all treatment groups was lower than in the control group. Both BCG and Ro 10-9359 were effective in decreasing the percentage of tumor takes and the simultaneous use of these agents was more effective than either one alone. Ro 10-9359 was found to possess more antitumor activity than Ro 4-3780 in this tumor model. Treatment of mice with a combination of Ro 10-9359 and BCG resulted in an 83.3 per cent incidence of complete tumor regression within 80 days. Results suggest that vitamin A derivatives may be useful in the prevention and treatment of bladder cancer and that the activity is likely potentiated by nonspecific stimulation.

Keyhole-limpet haemocyanin (KLH) immunotherapy of murine transitional cell carcinoma.

The antigenicity of transitional cell carcinoma of the bladder has stimulated the search for effective immunotherapeutic agents in the treatment of this disease. Non-specific immunotherapy with local (intravesical/intralesional) and systemic Keyhole Limpet Haemocyanin (KLH) in a FANFT induced murine bladder tumor model was studied. Results showed no difference between control or treated groups in either tumor growth or animal survival.