Deforolimus (AP23573) a novel mTOR inhibitor in clinical development.

mTOR was determined to be a promising anticancer target and several drug inhibitors of mTOR are currently in clinical development. Rapamycin (RAP) was the first mTOR inhibitor discovered. However, RAP has poor aqueous solubility and chemical stability and therefore its utilization at doses susceptible to produce an effect as an anticancer agent is limited.