**11.4 Atezolizumab**

The first PD-L1 inhibitor to receive FDA approval was atezolizumab. An openlabel, phase I dose-escalation analysis (NCT01375842) showed that Atezolizumab is safe in patients with locally advanced or metastatic solid tumors (**Table 3**). A cohort of 54 patients with mTNBC was evaluated for protection, and 21 patients were evaluated for efficacy in this study. 69% of the patients in the protection cohort had PD-L1 expression of at least ≥5%, and all of the patients in the efficacy cohort had PD-L1 expression of at least ≥5%. The ORR for this study was 19%. There were three patients who had pseudoprogression, but their tumors gradually shrink. A total of 63% of patients experienced drug-related side effects, with 11% experiencing grade 3 toxicity. Pneumonitis of grade 4 was diagnosed in one of the patients. Fatigue (15%), fever (15%), and nausea (15%) were the most common drug-related side effects [67].
