Timing of Adjuvant Durvalumab Initiation Is Not Associated With Outcomes in Stage III Non-small Cell Lung Cancer

Abstract

It is unclear whether time from radiation therapy (RT) completion to durvalumab initiation influences the outcomes of stage III non-small cell lung cancer (NSCLC) treated with definitive chemoradiation and adjuvant durvalumab. Using the US Veterans Health Administration database, we retrospectively identified 728 patients with stage III NSCLC treated with definitive chemoradiation who started durvalumab within 120 days of radiation completion. Time between the last radiation treatment and first durvalumab infusion was analyzed in multivariable Cox regression models for the primary outcomes of progression-free survival (PFS) and overall survival (OS), adjusting for baseline patient and disease characteristics. The primary analysis used a 120-day landmark, measuring OS and PFS from 120 days after radiation completion. Among 728 patients, the median time from RT completion to durvalumab start was 41 days (interquartile range 30-58). In multivariable Cox regression, time from RT completion to durvalumab start showed no association with PFS (adjusted hazard ratio [aHR] 1.01 per week, 95% confidence interval [CI] 0.98-1.04, P=.4) or OS (aHR 1.02 per week, 95% CI 0.98-1.06, P=.3). Starting durvalumab ≤14 days after RT was also not associated with improved PFS or OS. Results were robust in sensitivity analyses varying analytical technique. Timing of durvalumab initiation up to 120 days after RT completion is not associated with PFS or OS in this real-world patient cohort.