Strong Inhibition of Xenografted Tumor Growth by Low-Level Doses of [(32)P]ATP

The ability of a potential human anti-cancer therapeutic agent to inhibit the growth of xenografted tumors in nude mice has been an established and accepted testing method for several decades. The current report shows that a single, low-level intravenous dose of [(32)P]ATP significantly inhibits the growth of established xenografted tumors in nude mice. This inhibitory effect becomes appreciable very rapidly, within only five days post-injection and the low dose demonstrates little or no toxicity in the mice. Surprisingly, a narrow dose window of optimum effectiveness is seen, whereby either decreasing or increasing the [(32)P]ATP dose results in far less growth inhibition. Thus, the intravenous systemic injection of [(32)P]ATP may represent a simple, potent method to target and inhibit primary human tumors and malignant lesions.