27. (Atezolizumab-Related Exclusion) Prior treatment with anti-PD-1, or anti-PD-L1 therapeutic antibody or pathway targeting agents a) Patients who have received prior treatment with anti-CTLA-4 may be enrolled, provided the following requirements are met: Minimum of 12 weeks from the first dose of anti-CTLA-4 and >6 weeks from the last dose No history of severe immune-related adverse effects from anti-CTLA 4 (NCI CTCAE Grade 3 and 4)