Combination chemo-immunotherapy with adriamycin in experimental tumor systems

Chemoimmune prophylaxis of superficial bladder cancer

Chemoimmune prophylaxis with intravenous cyclophosphamide and intravesical as well as systemic bacillus Calmette-Guerin treatment was begun after complete tumor resection in 90 patients with superficial urothelial bladder cancer. Compared to a historical patient control group treated by tumor resection alone a distinct decrease in the recurrence rate was noted in the immune treated group, which was most marked during the first 12 months postoperatively. The side effects of this treatment were tolerable. Our results are discussed with regard to the reported findings in the literature. Possible immune biological mechanisms of the tumor protection achieved by cyclophosphamide and bacillus Calmette-Guerin are suggested.

The heterogeneity of the interaction between cancer chemotherapeutic agents and host resistance mechanisms

Employing adriamycin and daunomycin as model drugs, evidence is presented that a differential effect on host defense mechanisms can be important in determining the therapeutic efficacy of antitumorals. The heterogeneity of these and other cancer chemotherapeutic agents in immunocyte populations such as macrophages, suppressor cells, and natural-killer cells is examined, and discussed is the possible relevance of this heterogeneity in understanding the mode of action and in better use of antitumorals in combined approaches.

Effect of chemotherapeutic agents on natural and BCG-stimulated macrophage cytotoxicity in mice

Spontaneous or Bacillus Calmette Guérin (BCG)-stimulated macrophage cytotoxicity was investigated in the peritoneal cavity of BALB/c x DBA/2 treated with various chemotherapeutic agents. The SV40-transformed mKSA TU5 (TU5) line and the mFS6 sarcoma were used as targets. Cytolytic activity of macrophages from individual mice (4-6 per experimental group) was measured as release of [3H methyl]thymidine from prelabelled target cells. Treatment with azathioprine (a single injection 100-400 mg/kg or 5 daily doses of 10-80 mg/kg s.c.) and dimethyltriazenoimidazole carboxamide (a single injection of 45-180 mg/kg or 5 daily doses of 3-30 mg/kg i.v.) resulted in marked dose-dependent inhibition of spontaneous macrophage cytotoxicity against TU5 tumor cells 2 days later. By 7 days after drug treatment spontaneous cytotoxicity of macrophages had returned to normal levels. In contrast adriamycin (a single dose of 5-10 mg/kg or 5 daily doses of 0.6-2.5 mg/kg i.v.) and cyclophosphamide (a single dose of 50-200 mg/kg or 5 daily doses of 6-25 mg/kg i.v.) did not affect spontaneous cytolytic activity of murine macrophages. BCG-stimulated macrophage cytotoxicity was investigated using mFS6 target cells which were relatively resistant to the spontaneous levels of macrophage-mediated cytolysis; the same pattern of effects was observed, azathioprine and dimethyltriazenoimidazole carboxamide inhibiting cytolytic activity levels in contrast to adriamycin and cyclophosphamide. These results are discussed in terms of the known effects of these agents on other functions of mononuclear phagocytes and on other immune reactivities.

Time in chemo-immunotherapy models: an absolute or a relative variable? Lessons from the levamisole experience

An analysis is presented of the findings from the available studies in several cancer models, where 2.5-20 mg/kg levamisole was given in combination with different types of cytostatic drugs. It appears that in chemo-immunotherapy experiments it may be preferable to measure time variables (increase in life span, timing of chemotherapy and of immunotherapy) as a per cent of the median survival time of the untreated controls instead of using time as an absolute measure (in days). As regards the study of levamisole in chemo-imnmunotherapy models, the increase in life span by the cytostatic alone seems to be the most important variable studied here. An "optimal" protocol for the evaluation of levamisole is proposed based upon all the findings of this analysis.