PDCD1 and small cell lung carcinoma: Recently, IMpower133 and CASPIAN assessed anti-PD-1/PD-L1 antibodies with or without anti-CTLA-4 antibodies as the first-line of therapy for patients with SCLC, revealing better therapeutic effects in prolonging OS and PFS in patients with SCLC than chemotherapy [16, 19], which indicated a major development in SCLC therapy.