NCT07413042 2026-02-17A 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 TreatmentPeking University Cancer Hospital & InstitutePhase 1 Recruiting24 enrolled