P42.03 Predictive Factors of Response to PD-(L)1 Inhibitors in Patients With Advanced Non-Small Cell Lung and High PD-L1 Expression

Abstract

Tumor PD-L1 expression is the only validated predictive biomarker in advanced NSCLC patients (pts) treated with PD-(L)1 inhibitors. Analysis of PD-L1 expression by immunohistochemistry has been validated in histological samples. Smoking and overweight have been described as predictive factors of better outcome, whereas bone metastases, antibiotics, corticosteroids and proton pump inhibitors as possible negative predictive factors. The aim of our study was to analyze different potential predictive factors to PD-(L)1 inhibitors in pts with advanced NSCLC and high PD-L1 expression. This retrospective study was carried out in pts with advanced NSCLC and high PD-L1 expression treated with PD-(L)1 inhibitors with median follow-up of 12.8 months [3.6-73.9]. Clinical and histological variables of interest were registered. Kaplan-Meier estimations were used to calculate survival, while the log-rank test was implemented to make comparisons. The impact of variables on survival was assessed through univariate and bivariate analysis. We included 86 pts, the mean age was 66 y [36-84], 24.4% were females, 73.3% were former smokers and 22.1% current smokers, 38,4% presented normal Body Mass Index, 79% pts had non-squamous NSCLC, and 12% pts had cytological sample for PD-L1 determination. 72 (83.7%) pts received monotherapy with PD-(L)1 inhibitor, 4 (4.7%) pts chemotherapy plus PD-(L)1 inhibitor and 10 (11.6%) pts received PD-(L)1 inhibitors with other immunotherapy drug. The median OS and PFS were 23.0 months (95% CI, 13.7 to 32.4) and 9.5 months (95% CI, 2.3 to 16.7), respectively. ORR and DCR in overall patients were 55.6% and 71.5%, respectively. The median OS in complete/partial response vs. stable disease vs. progression disease was not reached vs. 14.0 months (95% CI, 8.1 to 19.8) vs. 4.2 months (95% CI, 2.6 to 8.0), respectively (P<0,001). The median OS in patients receiving treatment beyond progression was not reached vs. 10.4 months (95% CI, 8.2 to 12.6) in patients that stopped treatment (P<0,001). A trend to better results were observed in patients with overweight or smokers, and a trend to worse OS was observed in pts with bone metastasis. No differences in OS were observed according to the tumor sample (cytological vs histological samples). Response to immunotherapy and treatment beyond progression were predictive of better outcome in pts with advanced NSCLC and high PD-L1 expression. No significant differences in survival were observed according to the type of tumor sample or clinical characteristics.