RecruitingPhase 2Drug trialChemo-Immunotherapy Followed by Durvalumab and Ceralasertib in Treatment Naïve Patients With Extensive Stage Small Cell Lung CancerThe primary objective of this single arm study is to estimate the progression free survival of previously-untreated patients with extensive stage small cell lung cancer. Patients will receive initial chemo-immunotherapy followed by maintenance therapy with durvalumab and oral ceralasertib.