Clinical Study on Using TCR to Predict the Effect of Tislelizumab + Chemotherapy in the First-line Treatment of ES-SCLC

This study looks at whether analyzing immune cell patterns (called TCR repertoire) in blood can predict how well people with extensive-stage small cell lung cancer respond to a combination of the immunotherapy drug tislelizumab and chemotherapy as their first treatment. **You may be eligible if...** - You have confirmed extensive-stage small cell lung cancer (cancer that has spread beyond one lung) - You have not yet received any systemic treatment for this cancer - You are in reasonable general health (able to care for yourself) - You are 18 years or older **You may NOT be eligible if...** - You have received prior chemotherapy or immunotherapy for this cancer - You have active autoimmune disease or are on immune-suppressing medications - You have untreated spread of cancer to the brain - You have serious heart or liver conditions Talk to your doctor to see if this trial is right for you.