Progression-Free Survival, Response Rate, and Disease Control Rate as Predictors of Overall Survival in Trials Evaluating Atezolizumab Regimens for Advanced, Locally Advanced, and Recurrent Non-Small Cell Lung Carcinoma

Primary lung cancer is currently the most common cancer worldwide and the leading cause of cancer death for men worldwide. Anti-cancer agents are usually categorized into three groups: cytotoxic agents, molecular-targeted agents, and immune checkpoint inhibitors. Immune checkpoint inhibitors are the newest treatment for many solid cancers and are drastically improve survival of patients with a variety of cancers. Chemotherapies, including cytotoxic agents, molecular-targeted therapies, and immune-checkpoint inhibitors, are recommended treatment options for advanced, recurrent, and relapsed non–small cell lung cancer (NSCLC). Because accumulated evidence has revealed that chemotherapies prolong patients' overall survival (OS) in a trial-level assessment, OS is the most widely accepted end point for randomized clinical trials (RCTs) examining lung cancer. This is because OS is simple to measure in an unbiased manner, is easy to interpret, and indicates a clear benefit for patients. The U.S Food and Drug Administration (FDA) and the European Medicines Agency consider OS the most reliable end point in regulatory settings concerning NSCLC chemotherapy. Nonetheless, OS requires long-term follow-up and large numbers of patients. In addition, OS is influenced by the later-line treatment and noncancer deaths. An attractive solution is to replace the OS with surrogate end points such as progression-free survival (PFS), response rate (RR), and disease control rate (DCR). Although many published trials choose this strategy, the surrogacy of PFS, RR, and DCR for OS has not yet established for patients treated by immune checkpoint inhibitor. Without the validation of the surrogacy, we could not properly interpret studies that adopted PFS, RR, or DCR as the primary endpoint.