This is an open-label, multicenter, single-arm, two-stage, Phase Ib study designed to assess
the safety, tolerability, and pharmacokinetics of oral cobimetinib with intravenous (IV)
atezolizumab and bevacizumab in participants with metastatic colorectal cancer (mCRC) who
have received and progressed on at least one prior line of therapy that contained a
fluoropyrimidine and oxaliplatin or irinotecan. There are two stages in this study: Stage 1
(safety run-in phase) and Stage 2 (dose expansion phase with two cohorts, an expansion cohort
and a biopsy cohort).