The effect of copper and other metal ions on the antitumor activity of pyruvaldehyde bis(thiosemicarbazone).

Pyruvaldehyde bis(thiosemicarbazone) (PTS) was tested alone and in combination with dietary copper sulfate on 10 tumor systems. Potentiation of the cancerostatic activity of PTS by copper sulfate occurred in 8 of the tumor systems: Sarcoma 180, Taper liver tumor (solid and ascites), Carcinoma 1025, Sarcoma T241, Ridgway osteogenic sarcoma, Mecca lymphosarcoma, and Walker Rat Carcinosarcoma 256 (W256) as well as in the estab lished 7-day-old W256 and 4-day-old Taper liver tumor (ascites). Copper ions appeared essential for activity of PTS in the treat ment of the solid Taper liver tumor. In W256, calcium and zinc, in addition to copper, were able to enhance the antitumor ac tivity of subinhibitory doses of the drug.