MEK inhibitor explained

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. (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]

Approved for clinical use

• Binimetinib (MEK162), approved by the FDA in June 2018 in combination with encorafenib for the treatment of patients with unresectable or metastatic BRAF V600E or V600K mutation-positive melanoma.^[4]
• 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.
• Selumetinib, had a phase 2 clinical trial for non-small cell lung cancer (NSCLC) which demonstrated an improvement in PFS,^[5] and is now in phase III development in KRAS mutation positive NSCLC (SELECT-1, NCT01933932). Other ph 3 clinical trials underway include uveal melanoma (failed), and differentiated thyroid carcinoma.
• Trametinib (GSK1120212), FDA-approved to treat BRAF-mutated melanoma. Also studied in combination with BRAF inhibitor dabrafenib to treat BRAF-mutated melanoma.

In clinical trials

• PD-325901, for breast cancer, colon cancer, and melanoma^[6] A phase II trial for advanced non-small cell lung cancer "did not meet its primary efficacy end point".^[7]

Others

• CI-1040, PD035901
• TAK-733, preclinical for multiple myeloma.^[8]

Pre-clinical investigation

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]}

Notes and References

1. Clinical experience of MEK inhibitors in cancer therapy . 2007 . 17194493 . 10.1016/j.bbamcr.2006.11.009 . 1773 . 8 . Biochim Biophys Acta . 1248–55 . Wang . Ding . Boerner . Scott A. . Winkler . James D. . Lorusso . Patricia M.. free .
2. Web site: ASCO: MEK Inhibitors—Alone or Paired With a BRAF Inhibitor—Increase Options, Benefits for Patients With BRAF-Mutated Advanced Melanoma . 2012 .
3. http://mct.aacrjournals.org/content/8/4/834.abstract KRAS/BRAF mutation status and ERK1/2 activation as biomarkers for MEK1/2 inhibitor therapy in colorectal cancer. 2009
4. Web site: Approved Drugs - FDA approves encorafenib and binimetinib in combination for unresectable or metastatic melanoma with BRAF mutations. Research. Center for Drug Evaluation and. www.fda.gov. en. 2018-07-17.
5. 10.1016/S1470-2045(12)70489-8 . Selumetinib plus docetaxel for KRAS-mutant advanced non-small-cell lung cancer: A randomised, multicentre, placebo-controlled, phase 2 study . 2013 . Jänne . Pasi A . Shaw . Alice T . Pereira . José Rodrigues . Jeannin . Gaëlle . Vansteenkiste . Johan . Barrios . Carlos . Franke . Fabio Andre . Grinsted . Lynda . Zazulina . Victoria . Smith . Paul . Smith . Ian . Crinò . Lucio . The Lancet Oncology . 14 . 38–47 . 23200175 . 1.
6. http://clinicaltrials.gov/show/NCT00147550 MEK Inhibitor PD-325901 To Treat Advanced Breast Cancer, Colon Cancer, And Melanoma
7. 20332327 . 10.1158/1078-0432.CCR-09-1920 . 16 . 8 . A phase II study of PD-0325901, an oral MEK inhibitor, in previously treated patients with advanced non-small cell lung cancer . Haura EB, Ricart AD, Larson TG, Stella PJ, Bazhenova L, Miller VA, Cohen RB, Eisenberg PD, Selaru P, Wilner KD, Gadgeel SM . Clin Cancer Res . 2450–7. 2010 .
8. http://www.nature.com/bcj/journal/v6/n2/full/bcj20167a.html MEK inhibitor, TAK-733 reduces proliferation, affects cell cycle and apoptosis, and synergizes with other targeted therapies in multiple myeloma. Feb 2016
9. Heavey. Susan. Cuffe. Sinead. Finn. Stephen. Young. Vincent. Ryan. Ronan. Nicholson. Siobhan. Leonard. Niamh. McVeigh. Niall. Barr. Martin. O'Byrne. Kenneth. Gately. Kathy. 2016-11-29. In pursuit of synergy: An investigation of the PI3K/mTOR/MEK co-targeted inhibition strategy in NSCLC. Oncotarget. 7. 48. 79526–79543. 10.18632/oncotarget.12755. 1949-2553. 5346733. 27765909.
10. Heavey. Susan. O'Byrne. Kenneth J.. Gately. Kathy. April 2014. Strategies for co-targeting the PI3K/AKT/mTOR pathway in NSCLC. Cancer Treatment Reviews. 40. 3. 445–456. 10.1016/j.ctrv.2013.08.006. 1532-1967. 24055012.
11. Luszczak. Sabina. Kumar. Christopher. Sathyadevan. Vignesh Krishna. Simpson. Benjamin S.. Gately. Kathy A.. Whitaker. Hayley C.. Heavey. Susan. 2020. PIM kinase inhibition: co-targeted therapeutic approaches in prostate cancer. Signal Transduction and Targeted Therapy. 5. 7. 10.1038/s41392-020-0109-y. 2059-3635. 6992635. 32025342.