Niraparib Added to Anti-PD-L1 Antibody Maintenance in SLFN11-positive, Extensive-disease SCLC

This study is testing whether adding the PARP inhibitor niraparib (a drug that blocks cancer cells from repairing their DNA) to standard immunotherapy maintenance can improve outcomes for patients with extensive-stage small cell lung cancer (ES-SCLC) whose tumors show high levels of a protein called SLFN11 — which may predict a better response to this combination. **You may be eligible if...** - You have confirmed extensive-stage small cell lung cancer (Stage IV) - Your tumor shows high expression of the SLFN11 protein (assessed by a central laboratory) - You completed 4 cycles of standard first-line chemo-immunotherapy (platinum/etoposide + atezolizumab or durvalumab) without disease progression - You are in reasonably good health (ECOG score 0-2) and are 18 or older **You may NOT be eligible if...** - Your cancer is progressing - You have active brain metastases causing symptoms - You have another active cancer - You have significant kidney, liver, or blood count abnormalities Talk to your doctor to see if this trial is right for you.