Abstract 4056: Correlation analysis between PD-L1 expression, TMB and clinical characteristics in Chinese non-small cell lung cancer

Abstract

Abstract Background: Immunotherapy has played an increasingly important role in the treatment of non-small-cell lung cancer (NSCLC) and it was approved for the first-line treatment of advanced lung cancer. PD-L1 expression and TMB are two important immunotherapy biomarkers, however, the relationship between PD-L1 expression, TMB and clinical features is still unclear. Methods: A total of 205 Chinese NSCLC patients (pts) including 120 males and 85 females with a median age of 61.5 years (range 31-84) were enrolled. Tumor stage was evaluated according to the 8th edition of the AJCC/UICC TNM staging system for NSCLC. FFPE tumor and matched blood samples were collected for NGS based 450[[Unsupported Character - Codename ­]]gene panel assay. TMB was assessed by standard NGS algorithms. TMB data (median: 5.4 muts/Mb, range 0.8-68.9 muts/Mb) from 206 lesions were provided for analysis. 172, 16 and 18 lesions tissues were analyzed for PD[[Unsupported Character - Codename ­]]L1 expression by IHC with 22C3, 28-8 and ZR3 antibodies, respectively. Results: According to TNM staging system, pts were divided into stage I (44 pts), stage II (20 pts), stage III (40 pts) and stage IV (101 pts). The pathological types of pts are adenocarcinoma (69.4%), squamous cell carcinoma (18.4%) and other types (12.1%). 34.5% of lesions were positive for PD-L1 expression (TPS≥1%), including 25.7% PD-L1(TPS≥10%) and 16.5% PD-L1(TPS≥50%) respectively. Significant differences between males and females were observed in PD-L1 expression (TPS≥1%: 40.8% vs. 25.6%, p<0.05; TPS≥10%: 30.8% vs. 18.6%, p<0.05; TPS≥50%: 20.8% vs. 10.5%, p<0.05). In addition, males had higher TMB than females (median: 8.5 vs. 3 muts/MB, p<0.001). A higher percentage of males than females were identified with TMB≥10 muts/Mb (45.0% vs. 12.8%, p<0.001) and TMB≥20 muts/Mb (11.7% vs. 2.3%, p<0.05). The percentage of PD-L1 positive in advanced pts was higher than in stage I pts (TPS≥1%: 39.5% vs 19.6%, p<0.005; TPS≥10%: 30.7% vs 12.4%, p<0.005; TPS≥50%: 16.1% vs 5.2%, p<0.05). Squamous cell carcinoma had higher TMB than adenocarcinoma (median: 8.5 vs. 3.8 muts/MB, p<0.001). Squamous cell carcinoma had a higher percentage of TMB≥10 muts/Mb than adenocarcinoma (44.7% vs. 23.1%, p<0.01). A low correlation was observed between PD-L1 expression and TMB (p <0.001, r=0.2). Pts with PD-L1 TPS≥10% had higher TMB (median: 10 vs 3.8 muts/Mb, p<0.001) and pts with TMB≥10 muts/Mb had higher percentage of PD-L1 positive expression (50.8% vs 27.0%, p<0.001). Conclusion: In this study, we found the most commonly used two biomarkers for immune checkpoint inhibitors, PD-L1 expression and TMB, may be correlated with gender, stage and pathological type of NSCLC patients. There is also a weak correlation between these two biomarkers. Exploring the relationship between immune biomarkers and clinical features may better guide in screening more suitable patients for immune checkpoint blockade. Citation Format: Yang Yu, Xinglong Fan, Yucheng Wei, Zimin Liu, Zuping Lian, Hongxia Han, Ming Yao, Kai Wang. Correlation analysis between PD-L1 expression, TMB and clinical characteristics in Chinese non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4056.