This Phase 1, open-label, multicenter, global study will evaluate the safety, pharmacokinetics, and activity of RO5509554 and MPDL3280A administered in combination in patients with selected locally advanced or metastatic solid tumors that are not amenable to standard treatment. Patients who receive MPDL3280A and RO5509554 will continue to receive study drug as long as they experience clinical benefit in the opinion of the investigator or until unacceptable toxicity or symptomatic deterioration attributed to disease progression as determined by the investigator after an integrated assessment of radiographic data, biopsy results (if available), and clinical status, or withdrawal of consent.