A MEK inhibitor is a chemical or drug that inhibits the mitogen-activated protein kinase enzymes MEK1 and/or MEK2. They can be used to affect the MAPK/ERK pathway which is often overactive in some cancers. (See MAPK/ERK pathway#Clinical significance.)
Hence MEK inhibitors have potential for treatment of some cancers, [1] especially BRAF-mutated melanoma, [2] and KRAS/BRAF mutated colorectal cancer. [3]
Clinically approved MEK inhibitor Cobimetinib has been investigated in combination with PI3K inhibition in pre-clinical models of lung cancer, where the combined treatment approach lead to a synergistic anti-cancer response. [9] Co-targeted therapeutic approaches to have been suggested to induce improved anti-cancer effects, due to blockade of compensatory signalling, prevention or delay of acquired resistance to treatment, and the possibility of reducing dosing of each compound. [10] [11]