Oncolysis by Clostridia. II. Experiments on a Tumor Spectrum With a Variety of Clostridia in Combination with Heavy Metal

Summary

The oncolytic effects of intravenously injected spores of Cl. butyricum (M-55) have been tested in a series of mouse and rat tumors. The results depended on the strain of tumor used, the age and thereby the size of the tumor, and the species of animal. Since even in the most favorable circumstances the oncolysis is rarely complete, it was attempted to improve the results by the simultaneous application of a series of metabolic products of clostridia and of tumors. The results were essentially negative.

It was observed that porphyrins present in the tumor or formed during oncolysis had a deleterious effect on the growth of clostridia. If the activity of porphyrins was blocked by the parenteral or local application of heavy metals, particularly the proper iron compounds, a faster and more extensive lysis could be obtained. This was true not only for tumors which had only a moderate sensitivity to the clostridia but also for smaller tumors of sensitive strains. Oncolysis by a series of nonpathogenic strains of clostridia was tested on three different mouse tumors, and in each instance the effect could be enhanced by the simultaneous parenteral treatment with an iron dextran complex. These observations open a way for improvement of results of spore therapy that so far were not sufficiently satisfying.