Treatment rationale and design of the PROLONG study: safety and efficacy of pembrolizumab as first-line therapy for elderly patients with non-small cell lung cancer

Background: Pembrolizumab is recommended as first-line therapy for patients with advanced non-small cell lung cancer (NSCLC) and a Programmed cell death ligand-1 (PD-L1) tumor proportion score (TPS) of ≥50% without driver mutations. However, the safety and efficacy were not investigated among patients who were ≥75 years old. Methods: This open-label single-arm phase II study is designed to evaluate pembrolizumab as first-line therapy for patients who are ≥75 years old with advanced NSCLC and a PD-L1 TPS of ≥50% without driver mutations. The primary endpoint is progression-free survival, and the secondary endpoints are overall survival, objective response rate, safety, and quality of life. Recruitment started in October 2017 and is expected to continue for approximately 3 years. Conclusions: Given the currently poor prognosis of elderly patients with advanced NSCLC, we hope that the findings of this study will facilitate more effective treatment in this setting.