The paradoxical prognostic effects of T-cell-derived circulating DNA in EGFR-mutated advanced non-small-cell lung cancer involve the crosstalk between heme biosynthesis and immune microenvironment.

The paradoxical impact of T-cell-derived circulating DNA (T-cirDNA) and prognostication in advanced non-small cell lung cancer (NSCLC) has been reported. Further exploration was conducted in 158 EGFR-mutated NSCLC participants who received EGFR inhibitors, correlated with tumor PD-L1 score, CD8 tumor-infiltrating lymphocytes (TILs), and bulk RNA sequencing. We categorized T-cirDNA levels into three groups based on a previous study: undetectable (26.8%), low (≤ 1% ratio; 36.6%), and high (> 1% ratio; 36.6%). Undetectable and high T-cirDNA groups were independent factors correlated with favorable outcomes. The presence of intra-tumoral CD8 TILs (≥ 1%) was also an independent unfavorable prognostic factor; however, it had the lowest proportion in the low T-cirDNA group (16%). Tumor-immune microenvironment (TIME)-related gene set enrichment analysis revealed an overlapped significant heme biosynthesis signature correlated with poor outcome and diverse T-cirDNA group. Despite a high heme biosynthesis signature score in the undetectable T-cirDNA group, inverse correlation with CIBERSORT-activated CD4 memory T-cells was found (R - 0.79, p-value 0.019). Those findings were contrary to the low and high T-cirDNA groups. The significant contribution of heme biosynthesis was the overexpression of CPOX. Crosstalk of EGFR and COPX function prohibits the activation of CD4 + memory T-cells or the spatial intra-tumoral CD8 + T-cells. Undetectable T-cirDNA represents inactivated naïve T-cells and solely active downstream EGFR signaling.