A Phase I Study to Evaluate the Safety and Preliminary Efficacy of [225Ac]Ac-DOTATATE Injection Combined With Tislelizumab in the Maintenance Treatment Period for Patients of Extensive-stage Small Cell Lung Cancer (ES-SCLC) With Somatostatin Receptors (SSTR)+ as First-line Treatment

This is a phase I study to evaluate the safety and preliminary efficacy of \[225Ac\]Ac-DOTATATE injection combined with tislelizumab in the maintenance treatment period for patients of extensive-stage small cell lung cancer (ES-SCLC) with somatostatin receptors (SSTR)+ as first-line treatment.Patients with ES-SCLC who have completed the induction therapy of first-line standard treatment and are yet to enter the maintenance treatment period are planned to be enrolled.