Contribution of resident and circulating precursors to tumor-infiltrating CD8+ T cell populations in lung cancer [scRNA-Seq]

Purpose: The goal of this study is to delineate the processes of CD8+ T cell differentiation in primary NSCLC by integrating transcriptomic and tcr profiles. Methods: A combination of single cell RNA and TCR sequencing (scRNA-seq and scTCR- seq) was used, in tumors, normal tissues adjacent to the tumor (juxta-tumor), and circulating blood derived from 11 patients with untreated, primary NSCLC. Results: We show that precursor, memory-like CD8+ TILs include 2 main populations: one is also present in the blood (circulating precursors); the other is also present in juxta-tumor tissue and bears markers of memory resident T cells (resident precursors). Both precursor subtypes differentiate into a main population of terminal effectors through a similar “transitional” stage. Terminal effectors are not observed in blood or juxta-tumor tissue, are more clonally expanded, and express signatures of exhaustion. A significant proportion of transitional and terminal effectors also express cell cycle signatures and Ki67, suggesting that clonal expansion occurs in situ is part of the terminal differentiation process. 11 patients with early-stage, untreated NSCLC