A PHASE IB, MULTICENTER, OPEN-LABEL STUDY TO EVALUATE THE SAFETY, EFFICACY, AND PHARMAKOKINETICS OF RO6958688 IN COMBINATION WITH ATEZOLIZUMAB AFTER PRETREATMENT WITH OBINUTUZUMAB IN PATIENTS WITH PREVILOUSLY TREATED METASTATIC, MICROSATELLITE-STABLE COLORECTAL ADENOCARCINOMA WITH HIGH CECAM5 EXPRESSION