Testing the Addition of Radiation Therapy to the Usual Immune Therapy Treatment (Atezolizumab) for Extensive Stage Small Cell Lung Cancer, The RAPTOR Trial

For each patient, the maximum severity reported for both immune mediated and non-immune mediated adverse events will be used in the summaries. Adverse events will be summarized regardless of relationship to protocol treatment as assessed by the investigator. All adverse events, adverse events leading to withdrawal, interruption or modification of protocol treatment, grade >= 3 adverse events, and serious adverse events will be summarized. Deaths and cause of death will be summarized. The rate of treatment-related adverse events using National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE, version [v.]5.0) will be reported with the frequency and severity (e.g., type, grade, and attribution) by arm, the analysis will be performed at the time of both phase II and phase III (if applicable) primary endpoint analyses. All adverse events will be classified as either immune or non-immune mediated.

Assessed per Response Evaluation Criteria in Solid Tumors (RECIST). Will compare the distributions of PFS between treatment arms using a one-sided stratified log-rank test in all randomized eligible patients at 0.025 level. The rates at various timepoints (e.g., every 6 months after randomization) and medians of PFS for each arm will be estimated using the Kaplan-Meier method. The associated 95% CI will be calculated using Greenwood's formula and based on a log-log transformation applied on the survival function. If one stratum has less than 10 events, the stratification factor which contains the level with the smallest number of patients will be removed from the stratified analyses.

Will be similarly summarized and compared between experimental and control. The interaction between the treatment groups and tumor number groups will also be explored in Cox regression model.

Will be similarly summarized and compared between experimental and control. The interaction between the treatment groups and tumor number groups will also be explored in Cox regression model.

Tumor burden determined by central radiographic assessment, using both tumor number and tumor volume will be associated with PFS and OS benefit. The PFS and OS will be similarly summarized and compared between experimental and control in the following subgroups: 1) high or low tumor burden, using >= 4, 5, or 6 metastases as a cutoff; 2) high or low tumor burden, using the median of centrally reviewed radiographic tumor volume as a cutoff.