But in response to a comment in your prior post, I think it's really dangerous to assume / hope the drugs are equivalent because they target the same signaling pathway. People thought that of Tarceva and Iressa, but they didn't turn out equivalent. My gut feel is that you can substitute mAbs for each other, but small molecules can be flaky.
I can certainly respect and do agree there is no guarantee that MEK162 will turn out to have the same activity as selumetinib, even though both are MEK inhibitors. However, given that the trial will apparently not impact ARRY's cash flow, I think it makes sense to go for it.