I have a Mid-2014 15" Macbook Pro with the onboard Intel and discrete nvidia graphics. Running El Capitan. Installed Cubase Pro 8.5 and it would crash on startup always. I notice that during the launch at some point it would kind of flicker and then crash. Eventually I guessed that it might have something to do with dynamic switching. I downloaded gfxstatus and locked the Macbook Pro to the integrated (Iris) graphics processor and Cubase works consistently. If I lock it to the nvidia it crashes consistently. If I leave it at dynamic switching it crashes consistently (presumably because on launching cubase it tries to switch to nvidia).
Anyhow, this has been my observation. Hopefully this helps anyone who has been having the same issue and hopefully a fix is on the way.