CD274 and small cell lung carcinoma: Atezolizumab, an anti-PD-L1 monoclonal antibody (mAb), was the first ICI approved for extensive-stage SCLC (ES-SCLC) in combination with chemotherapy agents carboplatin and etoposide based on data from the IMpower133 trial (NCT02763579) [11], which found a median overall survival (OS) of 12.3 months [95% confidence interval (CI): 10.8–15.8] and median progression-free survival (PFS) of 5.2 months (95% CI: 4.4–5.6).