Early response and prognostic value of [18F]-FDG-PET/CT in 83 NSCLC patients treated with NIVOLUMAB

146 Objectives: Nivolumab has demonstrated efficacy in second-line treatment of non small cell lung cancer. However, most of the patients experience early progression upon nivolumab. We aimed at determining the role of [18F]-FDG-PET/CT in predicting response to nivolumab. Materials and Methods: We reviewed 83 patients with metastatic NSCLC who received nivolumab and performed 18F-FDG-PET/CT before (baseline PET) and after 4 injections of nivulomab (evaluation PET). For each lesion, Total Lesion Glycolysis (TLG ) were measured using a fixed threshold of 2.5 g.mL-1. TLG of every lesions were respectively summed for each patient on both baseline and evaluation PET. Percentage changes in TLG (ΔTLG) were calculated between the two PET/CT. Results of PET/CT were compared to decision of multidisciplinary team meeting (MDTM), progression free survival (PFS) and overall survival (OS). Results: Among the 83 patients, MDTM classified patients as having a response (n=36), progressive disease (n=17) following the first 4 injections. Median ΔTLG was -64.1% (-82.7;-12.9), and +145.8% (+76.4; +285.2) respectively. MDTM classified 30 patients as having a pseudoprogression (PP, n=30). After 2 additional injections of nivolumab, they were further classified as having progression (n=9) or confirmed pseudoprogression (n=22). Median ΔTLG was +123.7% (+27.66; +327.5) and +47.4% (+13.3; +152.7) respectively using the PET/CT performed after 4 injections. Only ΔTLG of patients with response by MDTM was significantly different from ΔTLG of the other groups (p +30%. Conclusions: This study demonstrated prognostic value and performance of PET/CT in assessment of early response to Nivolumab in NSCLC. Furthermore, it suggested that PET/CT could help to better classify patient with suspected pseudoprogression.