ENHANCEMENT OF THE THERMAL RESPONSE OF ANIMAL TUMORS BY CORYNEBACTERIUM-PARVUM

Abstract

The effect of C. parvum [Propionibacterium acnes] treatment on the thermal response of animal tumors was studied. Tumors were methylcholanthrene-induced (FSa-l) and spontaneous (FSa-ll) fibrosarcomas in C3Hf/Sed mice. C. parvum was given i.v. and was followed by local hyperthermia at 43.5.degree. 3 days later. Cell survival determined by lung colony assays showed that preadministration of C. parvum insignificantly enhanced the thermal response of both tumors. Studies of delay of tumor growth for FSa-11 demonstrated that the enhancement ratio decreased with increasing time of treatment and reached a minimum of .simeq. 1.7. The enhancement ratio for the time at hyperthermia which achieved tumor control in 1/2 of the treated tumors was 1.7. Together with previous results on normal tissue response, the therapeutic gain factor for obtaining 50% tumor control was 1.1 (1.7/1.55) for the weekly immunogenic FSa-11 tumor, while it was 2.3 for modrately immunogenic FSa-ll as reported previously.