Metabolic activity by 18F-FDG-PET/CT is predictive of early response after nivolumab in previously treated NSCLC.

BACKGROUND: Nivolumab, an anti-programmed death-1 (PD-1) antibody, is administered in patients with previously treated non-small cell lung cancer. However, little is known about the established biomarker predicting the efficacy of nivolumab. Here, we conducted a preliminary study to investigate whether 18F-FDG-PET/CT could predict the therapeutic response of nivolumab at the early phase. METHODS: Twenty-four patients were enrolled in this study. 18F-FDG-PET/CT was carried out before and 1 month after nivolumab therapy. SUVmax, metabolic tumour volume (MTV), and total lesion glycolysis (TLG) were calculated. Immunohistochemical analysis of PD-L1 expression and tumour-infiltrating lymphocytes was conducted. RESULTS: Among all patients, a partial metabolic response to nivolumab was observed in 29% on SUVmax, 25% on MTV, and 33% on TLG, whereas seven (29%) patients achieved a partial response (PR) based on RECIST v1.1. The predictive probability of PR (100% vs. 29%, p = 0.021) and progressive disease (100% vs. 22.2%, p = 0.002) at 1 month after nivolumab initiation was significantly higher in 18F-FDG on PET/CT than in CT scans. Multivariate analysis confirmed that 18F-FDG uptake after administration of nivolumab was an independent prognostic factor. PD-L1 expression and nivolumab plasma concentration could not precisely predict the early therapeutic efficacy of nivolumab. CONCLUSION: Metabolic response by 18F-FDG was effective in predicting efficacy and survival at 1 month after nivolumab treatment.