Efficacy and Safety of First-line Treatment for Extensive-stage Small Cell Lung Cancer Using a Combination Therapy of Trilaciclib, Envafolimab, Etoposide, and Carboplatin

This study is testing whether adding two drugs — trilaciclib (a bone marrow protector) and envafolimab (an immunotherapy) — to standard chemotherapy (etoposide plus carboplatin) improves outcomes for people with extensive-stage small cell lung cancer, a fast-growing lung cancer that has spread widely. **You may be eligible if...** - You are 18 years or older - You have small cell lung cancer confirmed by biopsy - Your cancer is extensive-stage (spread beyond one lung) - You have at least one measurable tumor on imaging - You have not yet received any systemic treatment for the extensive-stage disease **You may NOT be eligible if...** - You have received prior systemic anti-tumor treatment for extensive-stage SCLC - You have significant organ dysfunction - You have uncontrolled brain metastases - You have active autoimmune disease Talk to your doctor to see if this trial is right for you.