Array BioPharma and AstraZeneca have selected a third compound for their small molecule MEK anti-cancer program, triggering a $1 million milestone payment by AstraZeneca. The second compound was selected in January 2006, also triggering a $1 million milestone to Array.  In December 2003, Array partnered the oncology portion of its MEK program, including its lead compound, ARRY-142886 (AZD6244), for co-development and commercialization with AZ.  At that time, the companies established a collaboration for R&D of additional clinical candidates.  

According to Array, MEK is a critical enzyme at the intersection of several biological pathways, which regulates cell proliferation and survival as part of the Ras/Raf/MEK/ERK pathway. Constitutive activation of the Ras/Raf/MEK/ERK pathway has been implicated in many cancers, including lung, pancreatic, colon, melanoma and thyroid caused by cancer-associated, mutational activation of bRAF and Ras proteins. MEK inhibition is seen as an attractive anti-cancer strategy as it has the potential to block inappropriate signal transduction regardless of the upstream position of the oncogenic aberration.