Divergent outcomes of anti-PD-L1 treatment coupled with host-intrinsic differences in TCR repertoire and distinct T cell activation states in responding versus non-responding tumors

• Published in: Frontiers in immunology Vol. 13; p. 992630
• Main Authors: John, Jessy, Woolaver, Rachel A, Popolizio, Vince, Chen, Samantha M Y, Ge, Huaibin, Krinsky, Alexandra L, Vashisht, Monika, Kramer, Yonatan, Chen, Zhangguo, Wang, Jing H
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 18.10.2022
• Subjects: Animals; Carcinoma, Squamous Cell; CD8-Positive T-Lymphocytes; head and neck squamous cell carcinoma; immunological heterogeneity; Immunology; individualized anti-tumor immune responses; Lymphocyte Activation; Lymphocytes, Tumor-Infiltrating; Mice; Receptors, Antigen, T-Cell - genetics; single cell-T cell receptor sequencing; TCR repertoire; individualized anti-tumor immune responses; immunological heterogeneity; TCR repertoire; single cell-T cell receptor sequencing; head and neck squamous cell carcinoma
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2022.992630

Differential responses to immune checkpoint inhibitors (ICI) may be attributed to tumor-intrinsic factors or environmental cues; however, these mechanisms cannot fully explain the variable ICI responses in different individuals. Here, we investigate the potential contribution of immunological heterogeneity with a focus on differences in T-cell receptor (TCR) repertoire to ICI responses, which has not been defined previously. To reveal additional factors underlying heterogeneous responses to ICI, we employed a squamous cell carcinoma (SCC) mouse model in which tumor-bearing recipients unambiguously diverged into responders (R) or non-responders (NR) upon anti-PD-L1 treatment. Treatment efficacy absolutely required CD8 T-cells and correlated positively with effector functions of CD8 tumor-infiltrating lymphocytes (TILs). We showed that TCR repertoires exhibited a similar magnitude of clonal expansion in R . NR CD8 TILs. However, the top expanded TCR clonotypes appeared to be mutually exclusive between R and NR CD8 TILs, which also occurred in a recipient-specific manner, demonstrating preferential expansion of distinct TCR clonotypes against the same SCC tumor. Unexpectedly, R . NR CD8 TILs reached all activation clusters and did not exhibit substantial global differences in transcriptomes. By linking single-cell transcriptomic data with unique TCR clonotypes, CD8 TILs harboring top TCR clonotypes were found to occupy distinct activation clusters and upregulate genes favoring anti-tumor immunity to different extents in R . NR. We conclude that stochastic differences in CD8 TIL TCR repertoire and distinct activation states of top TCR clonotypes may contribute to differential anti-PD-L1 responses. Our study suggests that host-intrinsic immunological heterogeneity may offer a new explanation for differential ICI responses in different individuals, which could impact on strategies for personalized cancer immunotherapy.