Contribution of resident and circulating precursors to tumor-infiltrating CD8+ T cell populations in lung cancer [scTCR-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. 6 patients with early-stage, untreated NSCLC