Experimental cancer immunotherapy in DBA/2 mouse-mastocytoma model utilizing autologous tumor tissue polymerised with ethylchlorformiate.

The effects of the specific active cancer immunotherapy utilizing autologous tumor tissue particles polymerised with ethylchlorformiate, and used in combination with PPD tuberculin, were studied with respect to the growth of mastocytoma (P-815 X 2) in DBA/2 mice. As a control material, animals not immunised or immunised only with the nonspecific reticuloendothelial system stimulator, PPD tuberculin, were used. The frequency of the tumor metastases in the organs surveyed (lymph nodes, spleen, liver, kidney, lung and thymus) was lowest in mice having received the specific immunotherapy regimen. Similarly, the signs of tumor rejection by the host (tumor-associated fibrous scar, lymphocyte and plasma cell infiltration, and disappearance of the tumor tissue totally or subtotally) were found to be most pronounced in this series of mice. The findings were discussed against the background of the successful clinical trials made with this mode of specific cancer immunotherapy during the recent few years in patients whose neoplasia had escaped the reach of conventional cancer therapy. The findings were also discussed in the light of the mechanisms involved in cancer immunity in general, and a conclusion was drawn that this kind of specific active cancer immunotherapy seems to exert beneficial effects on the host's immune system, and thus seems to contribute to tumor rejection by the host.