Impact of radiotherapy on outcomes of nivolumab in advanced non-small cell lung cancer: a case controlled study

Abstract

Aim: Pre-clinical studies have shown radiotherapy augmenting efficacy of immunotherapy in NSCLC, however the clinical benefits are yet to be defined. This study aims to determine the effects of previous radiotherapy on outcomes of nivolumab in patients with advanced NSCLC. Methods: Consecutive patients who received nivolumab on an intention-to-treat basis over 30 months between January 2015 and June 2017 at a large thoracic-oncology unit were identified. Outcomes in patients who received radiotherapy to the chest prior to commencing nivolumab (RT group, n=23) were compared to a matched cohort of patients who did not receive radiotherapy (non-RT group, n=23). Results: The RT group had received a mean 53.3 Gy (SD 12.3) at a median of 11 months prior to nivolumab. The median progression free survival (PFS) was 4.4 months (95%CI 3.4 to 5.3) in the RT group compared to 1.4 months (95%CI 1.0 to 1.8) in the non-RT group (p=0.01). Median overall survival (OS) was 10.3 months (95%CI 8.6 to 11.9) and 5.3 months (95%CI 2.0 to 8.5) in the RT and non-RT group respectively (p=0.04). Disease response on the initial assessment following starting nivolumab included nine (39.1%) patients with stable disease or partial response in the RT group compared to five (21.7%) in the non-RT group after a median of four cycles of treatment. Immune related complications were seen in 35% (n=7) and 15% (n=3) of patients in the RT and non-RT groups respectively (p=0.1). Conclusion: Previous radiotherapy resulted in longer survival in patients treated with nivolumab for advanced NSCLC. A trend towards a higher rate of favourable response was also seen with radiotherapy.