STK11/TP53 co-mutated non-small cell lung cancer (NSCLC) to display a unique tumor microenvironment (TME) and metabolic profile.
Authors: Naqash Abdul Rafeh , Floudas Charalampos S. , Maoz Asaf , Xiu Joanne , Baca Yasmine , Zeng Jia , Kim Chul , Judd Julia , Raez Luis E. , Lopes Gilberto , Nieva Jorge J. , Borghaei Hossein , Korn Wolfgang Michael , Takebe Naoko , Liu Stephen V. , Mamdani Hirva 
Published: June 2021

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Background: Recent data suggest inferior responses to immune checkpoint inhibitors (ICIs) in STK11-mt NSCLC. TP53 is a critical tumor suppressor gene regulating DNA repair by arresting cells in the G1 phase in response to critical double strand breaks. We hypothesized that accumulated DNA damage from mutations in the TP53 gene might increase immunogenicity and potentially enhance benefit of ICIs in STK11-mt NSCLC. Methods: A total of 16,896 NSCLC tumors submitted to Caris Life Sciences (Phoenix, AZ) for targeted NGS (DNA-Seq, 592 genes) were analyzed. A subset (N = 5034 tumors) had gene expression profiling (RNA-Seq, whole transcriptome). PD-L1 (TPS) was tested with 22c3 antibody (Dako). Exome-level neoantigen load for STK11-mt NSCLC was obtained from published TCGA Pan-immune analysis (Thorsson et al. 2018). Non-parametric tests were used for comparing differences in tumor mutational burden (TMB) and neoantigen load. Transcriptomic analysis included differential gene expression and hierarchical clustering. Tumor immune cell content was obtained from transcriptome using Microenvironment Cell Population-counter (MCP). Publicly available data from the POPLAR/OAK trials of atezolizumab in advanced NSCLC were used to model PFS and OS for STK11-mt with TP53-mt (n = 14) and without TP53-mt (n = 20). Results: Of 16,896 NSCLC samples, 12.6% had an STK11-mt with the proportions of TMB-high (≥10 Mut/Mb), PD-L1 ≥ 50% and MSI-high being 55.9%, 11.8%, and 0.72%, respectively. STK11-mt vs. STK11-wt NSCLC did not differ in median TMB (Caris:10 vs. 10 Mut/Mb; p > 0.1) or neoantigen load (TCGA: 154.5 vs. 165; p > 0.1). Median TMB (13 vs. 9 Mut/Mb; p < 0.001) and neoantigen load (263 vs. 134; p < 0.001) were higher in STK11-mt/ TP53-mt vs. STK11-mt/ TP53-wt. MCP analysis showed higher CD8, NK-cell and lower myeloid dendritic cell infiltration in STK11-mt/ TP53-mt vs. STK11-mt/ TP53-wt (p < 0.01). Expression of MYC and HIF-α were increased in the STK11-mt/ TP53-mt vs. STK11-mt/ TP53-wt (p < 0.01) along with higher expression (p < 0.01) of genes associated with both glycolysis ( HK2, LDHA, ALDOA) and glutamine metabolism ( GOT2, PPAT2). Hierarchical clustering of STK11-mt adenocarcinomas (n = 463) for STING pathway genes (CCL5, CXCL10, cGAS) identified a STING-high and a STING low cluster. The STING high cluster was significantly enriched in TP53-mt (48 vs. 32%; p < 0.01).In the OAK/POPLAR cohort, median OS (HR is 1.14, 95% CI 0.53 - 2.48); p > 0.1) and PFS (HR 1.88, 95% CI 0.89-3.97, p = 0.098) were not statistically different between STK11-mt/ TP53-mt vs. STK-mt/ TP53-wt. However, the 15-months PFS was 21% in the STK11-mt/ TP53-mt vs 0% in the STK11-mt/ TP53-wt. Conclusions: STK11-mt NSCLC with TP53-mt are associated with an immunologically active TME with metabolic reprogramming. These intrinsic properties could be exploited to improve outcomes to ICIs in combination with metabolically directed agents.