Abstract 3272: Is PD-L1 expression a decision-making biomarker for immunotherapy: a meta-analysis and cross-sectional study

Abstract

Abstract Background: PD-L1 expression has been approved by FDA as a diagnosis for anti-PD-(L)1 therapy in several types of cancer, however, there were still discrepancies of the predictive value of PD-L1 expression. Here we aimed to systematically assess the value of PD-L1 expression in determining cancer patients who should be offered anti-PD-(L)1 therapy and to characterize PD-L1 expression in Chinese cancer population. Methods: Cochrane library, PubMed and Embase databases were systematically searched to include relevant studies published between January 2000 and June 2019. We also reviewed the reports from all major conference proceedings. All randomized controlled trials investigating anti-PD-(L)1 efficacy in solid tumors were initially included if overall survival (OS) data were stratified by PD-L1 expression. Differences in OS benefits between PD-L1-positive and PD-L1-negative patients were analyzed. Effect size derived from each study was pooled using a random-effects model. Data regarding PD-L1 expression in Chinese patients were obtained from a CAP-accredited and CLIA-certified laboratory. Results: Twenty-five RCTs involving 14,471 patients were included. OS benefit was observed in patients with either positive (HR=0.68 [0.63-0.73], P<0.00001) or negative (HR=0.86 [0.78-0.95], P=0.003) PD-L1 expression, though significant longer OS was achieved in patients that are PD-L1 positive (P interaction=0.0001). Superior PFS were observed in patients with positive PD-L1 expression (HR=0.69 [0.57-0.82]) while not with negative PD-L1 expression (HR=1.00 [0.85-1.19]). PD-L1-positive patients exhibited significantly improved ORR than those who tested negative for PD-L1 when treated with immunotherapy (OR=0.50 [0.39-0.65], P<0.00001), while no differences were observed among patients given SOC (OR=1.02 [0.86-1.21], P=0.81). Analysis of Chinese patients PD-L1 status revealed that thymoma and small cell lung cancer expressed the highest and the lowest levels of PD-L1, respectively. Conclusion: PD-L1 expression alone is not determinative in patient selection for anti-PD-(L)1 treatment. Multiple modality biomarkers should be considered for cancer patients especially for those with PD-L1-negative tumors. Citation Format: Zhijie Wang, Jianchun Duan, Longgang Cui, Shangli Cai, Jie Wang. Is PD-L1 expression a decision-making biomarker for immunotherapy: a meta-analysis and cross-sectional study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3272.