134P - TERT-associated DNA polymerases genes link CAF and CD8+ T cells to improve immunotherapy response rate across multiple cancers

Background

Cancer cells exhibit heightened basal levels of responses to DNA breaks, accumulating DNA polymerases family (DNA-pol) as repair protein, thereby increasing DNA mutation and neoantigens. Based on this, we investigated the potential of DNA-pol as an immunotherapy biomarker and its underlying mechanism.

Methods

We conducted a pan-cancer analysis of DNA-pol gene dysregulation in 6366 samples. Normal fibroblast, cancer-associated fibroblast, and CD8+ T cells were cultured from cancer patients (3 esophagus, 5 lung, 5 renal, and 3 liver cancer), then treated them with PD-L1 inhibitor or overexpressing TERT for RNA-seq and proteomics. 996 multiple cancer cases with ICIs were collected to test biomarker efficiency. A phase II clinical trial is evaluating our biomarker prospectively.

Results

We defined a distinct signature score of DNA-pol genes upregulated in cancer (DNA-pol-up) and linked to worse prognosis (HR=1.2). DNA-pol-up program dysregulation led to immune processes alteration and was related to upstream activation of TERT signaling (z-score=3.6) in ingenuity pathway analysis and linked to immunologically active tumors by recruiting CD8+ T cell and downregulating CAF. DNA-pol-up score was elevated in PD-L1-treated CAF and TERT-overexpressed CD8+ T cell, in MSI-H cancer, also related to more neoepitope peptides, TMB (Rho=0.54), cancer stemness (Rho=0.78), and tumor purity (Rho=0.29). Cancers that activate this program carried distinct genomic profiles with PIK3CA, KRAS, and TP53 mutations. This signature was an independent predictor for ICIs response (OR=2.52), even outperforming cytolytic activity, MSI, TMB (OR=0.9). In 12 clinical trial datasets, this signature could stratify the responding patients (maxAUC=0.762). In our phase II clinical trial, 34 liver cancer were enrolled with 3-year follow-up, it also has a satisfactory performance in predicting the ORR (AUC=0.699) and classifies mortality rate (HR=2.3).

Conclusions

Our findings identify a distinct transcriptional pattern of DNA-pol genes across cancers, which highlighted the role of DNA-pol family genes in predicting the immunotherapy response for the first time, and TERT could be a novel vaccine candidate for improving immunotherapy response.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

X. Bi, H. Zhao, Z. Luo.

Funding

Zhiwen Luo was awarded a funding for research in Israel (China Scholarship Council No. 202106210312). CAMS Innovation Fund for Medical Sciences (CIFMS) (2021-I2M-C&T-B-043, 2021-I2M-C&T-B-052); Beijing CSCO Clinical Oncology Research Foundation (Y-XD202001-0111, Y-2019AZMS-0082, Y-XD202002-0370).

Disclosure

All authors have declared no conflicts of interest.