First Line Therapy for Extensive SCLC Patients, Treated with Chemo+Keytruda Followed by Keytuda+Trodelvy

This study tests a two-phase treatment for extensive-stage small cell lung cancer (a fast-growing type of lung cancer that has spread widely). The first phase combines chemotherapy with pembrolizumab (an immunotherapy). The second phase switches to pembrolizumab plus sacituzumab govitecan (a targeted drug that delivers chemotherapy directly to cancer cells). **You may be eligible if...** - You are 18 or older with confirmed extensive-stage small cell lung cancer - You have not yet had systemic treatment for this cancer - You have measurable tumors on scans - You are in good health (ECOG 0–1) with a life expectancy over 3 months - Asymptomatic brain metastases are allowed **You may NOT be eligible if...** - You have already received treatment for extensive-stage SCLC (prior limited-stage treatment is allowed if disease-free for 6+ months) - Your blood counts or organ function are outside acceptable ranges - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.