Rapalogs in viral cancers.

At present, 150 clinical trials are registered with the National Cancer Institute, which investigate the efficacy of inhibitors of the PI3K/Akt/mTOR pathway against multiple cancers. Efficacy varies not so much with drug action, but with tumor type, as different cancer types (and different pre-clinical models) exhibit widely differing susceptibilities to mTOR inhibitors, such as rapamycin. Viral cancers appear to be among the most mTOR-addicted and most rapamycin-sensitive cancers. We discuss the different mTOR inhibitors that are currently available and in clinical trials. We also speculate how the molecular makeup of viral cancers could guide the selection and use of known and novel mTOR inhibitors to treat virus-associated malignancies.