The predictive role of PET/CT and bioumoral parameters in immunotherapy

1347 Objectives: Immunecheckpoint inhibitors (ICI) proved great efficacy in different neoplasms as single agent or combination therapy, being capable to induce deep and durable remissions. However severe adverse events may occur and about 40% of patients (pts) don’t benefit from the treatment. Predictive factors of response to ICIs are urgently needed in order to customize treatment. Methods: We retrospectively analyzed 59 pts (21 melanoma, 35 lung cancer, 1 urothelial carcinoma, 2 head and neck carcinoma) treated with ipilimumab, nivolumab, pembrolizumab and atezolizumab from 2010 to 2018 in any line. Basal PET/CT scan parameters (whole-body metabolic tumor volume -wMTV, total lesion glycolysis- wTLG, higher standardized uptake volume maximum and mean- SUV max and SUV mean) as well as basal neutrophil/lymphocyte- (NLR) and platelet/lymphocyte- (PLR) ratio were calculated for each patient. We investigated the association of these parameters with overall response rate (ORR), progression free survival (PFS) and overall survival (OS). Results: In the overall population ORR was 35.6 %; median PFS and OS were not reached. Basal NLR was associated with better PFS (Cox model HR [95% CI]= 1.2 [1.1;1.4], p= 0.008) and OS (1.2 [1.03;1.3], p= 0.018) as well as PLR (1.003 [1;1.006], p= 0.05 for PFS and 1.004 [1.001;1.006], p= 0.017 for OS). Among PET/CT parameters, pts with high wMTV had worse PFS (1.004 [1.001;1.007], p= 0.016), while no relation was found with ORR and OS. In patients treated in first line (49.2%) high NLR and PLR are associated with worse PFS (respectively 2.1 [1.3;3.3], p= 0.001 and 1.004 [1.001;1.007], p= 0.005). In these pts also wMTV and wTLG are associated with ORR (p=0.018 and p=0.029, Wilcoxon test) and PFS (1.005 [1.001;1.008], p= 0.008 and 1.1 [0.9;1.2] p= 0.009). No relation was found between SUV parameters and efficacy outcomes. Conclusions: Basal PET/CT and bioumoral values could prove to be useful in the prediction of outcomes to ICIs therapy in solid tumor by reflecting the systemic immunological status. Prospective studies are needed in order to better establish their effective role.