PDCD1 and small cell lung carcinoma: Nowadays, although the introduction of inhibitors of programmed cell death protein-1/programmed death-ligand 1 (PD-1/PD-L1) in combination with chemotherapy as a first-line treatment has led to a significant improvement in OS and progression free survival (PFS) [5], not all patients with SCLC benefit from this treatment schedule, and few alternative therapies are available for patients.