Abstract 2492: Association of TP53 and LRP1B co-mutation status with response to immunotherapy in lung squamous cell carcinoma
Authors: Yu Jiangyong , Zhou Zhipeng , Zhang Ping , Li Pansong , Li Xu , Tang Min , Fan Nannan , Wu Xiaonan , Nie Xin , Chen Xiaoyan , Ma Di , Chen Xi , Guan Yanfang , Xia Xuefeng , Yang Ling , Yi Xin , Li Lin 
Published: July 2021

Abstract
Background: Immunotherapy can induce a long response in part patients of lung squamous cell carcinoma (LUSC). And accurate biomarkers are needed for suitable populations. As important tumor suppressor, tumor protein p53 (TP53) and low density lipoprotein receptor-related protein 1B (LRP1B) genes may be associated with immunogenicity. However, the interaction of TP53 and LRP1B and its potential association with response to immunotherapy are not fully understood in LUSC.
Methods: Three cohorts were divided into four groups, respectively (A: TP53mut and LRP1Bmut, B: TP53mut and LRP1Bwild, C: TP53wild and LRP1Bmut, D: TP53wild and LRP1Bwild). 525 LUSCs form Geneplus database which performed next-generation sequencing were assessed the differences of genomic landscape, tumor mutation burden (TMB), and PD-L1 expression in four groups (cohort 1). TCGA-LUSC RNA data (n=466) from cBioPortal were used to evaluate immune cell infiltration thought single sample gene set enrichment analysis (cohort 2). The LUSCs (n=125) which received immunotherapy of POPLAR and OAK cohort were used to evaluate the efficacy of immunotherapy in four groups (cohort 3).
Results: The proportion of patients in A, B, C and D groups of cohort 1 was 26%, 59%, 2%, 13%, respectively, suggesting that most patients with LRP1B mutation also carry TP53 mutation (98.6%) in LUSC. This similar ratio is 88.2% in cohort 2 and 74.3% in cohort 3. For group A, the most common mutated gene except TP53 and LRP1B was CDKN2A (31%). Group B was MLL2(28%). Group C was CDKN2A (33%). Group D was FAT1 (13%). The median TMB was 14.4 mutations/Mb (2.9-80.0) in group A, 9.8 (0.96-95.0) in group B, 11.5 (2-25) in group C, 3.8 (0.96-18.2) in group D. TP53 and LRP1B co-mutation had a highest TMB compared with the other three groups in all cohorts, while TP53wild and LRP1Bwild completely opposite. In cohort 1, PD-L1 expression had no significant difference in four groups. In cohort 3, progression-free survival (PFS) was longer in group D compared with the other three groups (p = 0.047, A: 1.5m, B: 1.6m, C: 2.1m, D: 4.2m). The same trend on overall survival (OS) were found but it was not significant. Group D also had a higher disease control rate (A: 50%, B: 46%, C: 44%, D: 69%). We than divide into two groups (D vs Other) to compare PFS and OS. It showed that group D had a prolonged PFS (p = 0.02) and OS (p = 0.03). Multivariate cox regression analysis showed that the results were independent of TMB, gender and age. Analysis of immune cell infiltration in cohort 2 showed that the better outcomes of group D might associated with elevated infiltrations of activated dendritic cell and activated CD8 T cell.
Conclusion: TP53mut and LRP1Bmut, which accounted for a high proportion of LUSC, was associated with high TMB. And TP53wild and LRP1Bwild has better anti-PD-L1 outcome in LUSC. This might be related with a stronger activated dendritic cell and activated CD8 T cell infiltration despite lower TMB.
Citation Format: Jiangyong Yu, Zhipeng Zhou, Ping Zhang, Pansong Li, Xu Li, Min Tang, Nannan Fan, Xiaonan Wu, Xin Nie, Xiaoyan Chen, Di Ma, Xi Chen, Yanfang Guan, Xuefeng Xia, Ling Yang, Xin Yi, Lin Li. Association of TP53 and LRP1B co-mutation status with response to immunotherapy in lung squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2492.