title: Targeting the PI3K/AKT/mTOR and Raf/MEK/ERK pathways in the treatment of breast cancer.
abstract: Alterations of signal transduction pathways leading to uncontrolled cellular proliferation, survival, invasion, and metastases are hallmarks of the carcinogenic process. The phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) and the Raf/mitogen-activated and extracellular signal-regulated kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathways are critical for normal human physiology, and also commonly dysregulated in several human cancers, including breast cancer (BC). In vitro and in vivo data suggest that the PI3K/AKT/mTOR and Raf/MEK/ERK cascades are interconnected with multiple points of convergence, cross-talk, and feedback loops. Raf/MEK/ERK and PI3K/AKT/mTOR pathway mutations may co-exist. Inhibition of one pathway can still result in the maintenance of signaling via the other (reciprocal) pathway. The existence of such "escape" mechanisms implies that dual targeting of these pathways may lead to superior efficacy and better clinical outcome in selected patients. Several clinical trials targeting one or both pathways are already underway in BC patients. The toxicity profile of this novel approach of dual pathway inhibition needs to be closely monitored, given the important physiological role of PI3K/AKT/mTOR and Raf/MEK/ERK signaling. In this article, we present a review of the current relevant pre-clinical and clinical data and discuss the rationale for dual inhibition of these pathways in the treatment of BC patients.
authors: Breast International Group, Brussels, Belgium; Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium.
authors: Kamal S
authors: KS
authors: Saini
authors: Sherene
authors: S
authors: Loi
authors: Evandro
authors: E
authors: de Azambuja
authors: Otto
authors: O
authors: Metzger-Filho
authors: Monika Lamba
authors: ML
authors: Saini
authors: Michail
authors: M
authors: Ignatiadis
authors: Janet E
authors: JE
authors: Dancey
authors: Martine J
authors: MJ
authors: Piccart-Gebhart
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy* / Q000201:enzymology; D005260:Female; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D058539:Phosphatidylinositol 3-Kinase / Q000235:genetics / Q000378:metabolism*; D057285:Precision Medicine; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: C546842:MTOR protein, human; D058539:Phosphatidylinositol 3-Kinase; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D020928:Mitogen-Activated Protein Kinases
keywords: Breast cancer; Cross-talk; Dual inhibition; MAPK; PI3K; Personalized medicine; Ras/Raf/MEK/ERK; Targeted therapy; mTOR