Sex-linked inhibition of tumors by pyruvaldehyde Bis(thiosemicarbazone).

The tumor-inhibitory effect of pyruvalclehyde bis(thiosemicarbazone) was greater on 6 tumors carried in male mice and rats than in females. The effect of the compound on Walker 256 in castrated male rats was similar to that seen in females. In castrated males, the antitumor activity was less than that in normal males. The injection of estradici in such castrated males did not alter the effect. However, injection of testosterone restored the castrated animals to the same degree of response as normal males. In female animals, ovariectomy decreased the activity of pyruvaldehyde bis(thiosemicarbazone). Concurrent administration of testosterone to ovariectomized animals re sulted in antitumor activity comparable to that seen in males. The increased activity seen in males and animals receiving testos terone was achieved without increase in systemic toxicity.