Pembrolizumab and Olaparib Treatment of Extensive Small Cell Lung Cancer (ES-SCLC)

This study is testing a combination of two drugs — pembrolizumab (an immunotherapy) and olaparib (a targeted therapy) — as a first-line treatment for extensive-stage small cell lung cancer, meaning the cancer has spread beyond the chest. **You may be eligible if...** - You are 18 or older with confirmed extensive-stage small cell lung cancer - You have not previously received any systemic treatment for this cancer (or had prior chemoradiation for early-stage disease at least 6 months ago) - Your cancer has at least one measurable lesion on a scan - You are generally active and able to carry out daily activities - Your liver, kidneys, and blood counts are functioning adequately - HIV, hepatitis B, and hepatitis C tests are negative (or controlled) **You may NOT be eligible if...** - You have active, untreated brain metastases - You have an active autoimmune disease requiring systemic treatment (some exceptions apply, such as controlled thyroid disease or type 1 diabetes) - You have had a prior PARP inhibitor (like olaparib) or prior anti-PD1/PD-L1 immunotherapy - You have significant heart problems or a history of severe lung inflammation - You are pregnant or breastfeeding - You have had a major surgery within 4 weeks - You take strong medications that interact with olaparib Talk to your doctor to see if this trial is right for you.