Therapeutic targets: MTOR and related pathways

Cancer Biol Ther. 2006 Sep;5(9):1065-73. doi: 10.4161/cbt.5.9.3175. Epub 2006 Sep 6.


The mammalian target of rapamycin (mTOR), a protein kinase of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway, has a central role in controlling malignant cellular growth. As a result, mTOR is viewed as an important target for anticancer drug development. Inhibitors of mTOR currently under evaluation in cancer clinical trials are rapamycin (also known as sirolimus, Wyeth) and derivatives temsirolimus (CCI-779, Wyeth), everolimus, (RAD001, Novartis Pharma AG), and AP23573 (Ariad Pharmaceuticals). Preclinical studies suggest that sensitivity to mTOR inhibitors may correlate with activation of the PI3K pathway and/or with aberrant expression of cell cycle regulatory or anti-apoptotic proteins. Clinical trial results show that mTOR inhibitors are well tolerated and may induce prolonged stable disease and tumor regressions in cancer patients. Future research should evaluate optimal, schedule, patient selection, and combination strategies for this novel class of agents.

Publication types

  • Review

MeSH terms

  • Antibiotics, Antineoplastic / pharmacology
  • Clinical Trials as Topic
  • Everolimus
  • Humans
  • Neoplasms / drug therapy*
  • Neoplasms / enzymology*
  • Protein Kinase Inhibitors / pharmacology
  • Protein Kinases / metabolism*
  • Sirolimus / analogs & derivatives*
  • Sirolimus / pharmacology*
  • Sirolimus / therapeutic use
  • TOR Serine-Threonine Kinases


  • Antibiotics, Antineoplastic
  • Protein Kinase Inhibitors
  • temsirolimus
  • Everolimus
  • Protein Kinases
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • Sirolimus