This study is for patients with a type of lung cancer called Extensive Stage Small Cell Lung Cancer (ES-SCLC). The study uses biomarker tests, which are tests that look for specific features in cancer cells, to help select personalized treatments. These treatments aim to keep the cancer under control after initial therapy. Participants will receive one of several drugs, including durvalumab, saruparib, ceralasertib, or monalizumab, based on their cancer's characteristics. These drugs work by helping the immune system attack cancer, stopping cancer cells from fixing damaged DNA, or blocking enzymes that help tumor growth.

• This study involves regular treatments and check-ups during and after the treatment period, up to 3 years.
• Participants must be willing to undergo various scans and provide tissue and blood samples.
• Potential side effects and risks will be monitored throughout the study.

Participants must be at least 18 years old, cannot be pregnant or nursing, and must agree to use contraception. The study requires good health at the start and no recent exposure to certain medications or vaccines. It's essential for participants to discuss their eligibility and the study details with their doctor.