Combination Rucaparib With Nivolumab in Small Cell Lung Carcinoma

Inclusion Criteria * Patients with histologically or cytologically confirmed stage IV, extensive stage, small cell lung cancer who achieved either partial or complete remission per RECIST 1.1 post frontline chemotherapy with platinum doublet (Cisplatin or Carboplatin/etoposide). * Enrollment is within 6 weeks of last (4th cycle) of chemotherapy. * Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2 * Adequate Bone Marrow Function * Adequate Hepatic Function Exclusion Criteria * Prior therapy with any antibody/drug targeting T-cell co-regulatory proteins (immune checkpoints) * Major surgery within 4 weeks of initiation of study medication. * Current use of (some) immunosuppressants * Active infection requiring systemic therapy * HIV/AIDS * Hepatitis B virus or hepatitis C virus infection at screening * Autoimmune disease * Persisting toxicity related to prior therapy * Pregnancy * Vaccination (except inactive) within 4 weeks of the first dose of nivolumab * Hypersensitivity to the study drugs * Cardiovascular disease * Untreated central nervous system (CNS) metastases or leptomeningeal carcinomatosis * (Some) active secondary malignancy * Active pneumonitis or interstitial lung disease