A MEK inhibitor is a chemical or drug that inhibits the mitogen-activated protein kinase kinase enzymes MEK1 and/or MEK2. They can be used to affect the MAPK/ERK pathway which is often overactive in some cancers.
Hence MEK inhibitors have potential for treatment of some cancers, especially BRAF-mutated melanoma, and KRAS/BRAF mutated colorectal cancer.
Approved for clinical use
Trametinib (GSK1120212), FDA-approved to treat BRAF-mutated melanoma. Also studied in combination with BRAF inhibitor dabrafenib to treat BRAF-mutated melanoma.
Cobimetinib or XL518, approved by US FDA in Nov 2015 for use in combination with vemurafenib (Zelboraf(R)), for treatment of advanced melanoma with a BRAF V600E or V600K mutation.
In clinical trials
Binimetinib (MEK162), is currently in phase 3 clinical trials for ovarian cancer, BRAF mutant melanoma, and NRAS mutant melanoma.
Selumetinib, had a phase 2 clinical trial for non-small cell lung cancer (NSCLC) which demonstrated an improvement in PFS, and is now in phase III development in KRAS mutation
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