To evaluate the safety and preliminary efficacy of recombinant anti-PD-L1（Programmed cell death ligand 1）monoclonal antibody injection (ZKAB001) combined with carboplatin and etoposide in the treatment of extensive-stage small cell lung cancer. The study will last until the number of patients who permanently stop taking drugs due to toxicity in the first two cycles is less than 1/3 of the total number of patients.
To evaluate the safety and efficacy of recombinant anti-PD-L1 monoclonal antibody injection (ZKAB001) combined with carboplatin and etoposide in the treatment of extensive-stage small cell lung cancer.