A Study of GDC-0919 and Atezolizumab Combination Treatment in Participants With Locally Advanced or Metastatic Solid Tumors

Participants will receive atezolizumab at a fixed dose of 1200 milligrams (mg) via intravenous (IV) infusion on Day 1 of each 21-day cycle with the exception of biopsy cohort A, where atezolizumab administration will start on Cycle 2 Day 1.

Participants will receive GDC-0919 by mouth (PO) twice daily (BID), specifically every 12 hours. During the dose-escalation stage, the first cohort will receive GDC-0919 at a starting dose of 50 mg PO BID. Dosing will commence on Day -1 for Cycle 1 and follow subsequent 21-day (Days 1 to 21) dosing cycles. The dose will be modified based upon evaluation of DLTs, with single dose escalations not to exceed 2.5-fold of the previous dose. The proposed dosages for evaluation are 50, 100, 200, 400, 600, and 1000 mg PO BID. During the expansion stage, selected solid tumor types will be treated at the MTD or MAD as determined during the dose-escalation stage.