This is old news for me, but maybe of interest here. I'm on the Atezo/Cobi phase 1b trial. I'm microsatellite stable, K-RAS mutant. FOLFOX didn't help me much and FOLFIRI didn't help at all. I entered the trial in January 2016.
My side effects have been pretty manageable. The only reliable side effect is acne on my face and shoulders/chest while I'm on the Cobi. It started out pretty nasty as acne goes, but became less aggressive as the treatment went on. It's generally a significantly better quality of life than my first 2 rounds of chemo.
My first scan after treatment started showed a ~25% shrinkage. The second scan (4 months in) showed over 30% reduction, so I became a "responder". The tumors continued to shrink over many months and eventually showed ~60% reduction. In January of 2017 one of my "innumerable" tumors started to grow, despite Atezo/Cobi. My doc got permission to irradiate that tumor while keeping me on the trial. That worked well, but the next set of scans showed a couple of other tumors starting to grow again. So I'm still on the trial, but maybe not for much longer. Because of my start date in 2016 and my dose schedule (Cobi 2 weeks on, 2 weeks off) I know that I am not included in the results that were reported at ASCO 2016 on this trial. I was the first patient at MGH to get on that trial and my doc says MGH had "a couple of responses" to the combo. So there have been more responders on that trial than the four originally reported.
I'm happy to answer questions about this combo/trial if people have them.