Strain specificity of stimulated regression of sarcoma 180.

Various treatments capable of increasing the complete recovery rate of Swiss mice from growth of the solid tumor, Sarcoma 180, have been reported. In the present experiments 4 chemotherapeutic agents of diverse chemical type—6-mercaptopurmne, actinogan, phleomycin, and zymosan—as well as a pyridoxine-deficient diet, were tested for ability to promote regression of S-180 in Swiss Ha/ICR or DBA/2 mice. All treatments were found to be capable of increasing the recovery incidence among Ha/ICR mice, whether or not tumor inhibition had occurred by the end of the short course of therapy. However, only zymosan given i.v. at an optimum dose of 50 mg/kg increased recovery from S-180 when the tumor was grown in DBA/2 mice. This finding is consistent with the theory that stimulation of regression of S-180 in Ha/ICR mice may be largely dependent upon histocompatibility differences between tumor and host.