Tumor-Reactive CD8+ T Cells Enter a TCF1+PD-1- Dysfunctional State

Area of Science:

• Immunology
• Oncology
• Cancer Research

Background:

• T cells recognize tumor antigens, including self/shared-antigens (SSA) and tumor-specific antigens (TSA).
• Immune checkpoint blockade (ICB) can activate T cells against both TSA and SSA, leading to tumor control and immune-related adverse events (irAE), respectively.
• Understanding T-cell differentiation in response to different antigen types is crucial for optimizing cancer immunotherapies.

Purpose of the Study:

• To investigate the differentiation of tumor-specific CD8+ T cells (TST) and SSA-specific CD8+ T cells (SST) during liver cancer development.
• To determine how antigen specificity influences T-cell fate and function in the tumor microenvironment and systemic immunity.

Main Methods:

• Development of a genetic cancer mouse model for longitudinal tracking of TST and SST.
• Analysis of T-cell phenotype, function, and persistence in liver lesions and spleens.
• Assessment of T-cell responses to PD-1 or PD-L1 blockade.

Main Results:

• Both TST and SST lost effector function over time.
• TST persisted long-term with a dysfunctional/exhausted phenotype (PD1+, CD39+, TOX+).
• SST exited the cell cycle prematurely, disappeared from liver lesions, but persisted in spleens in a dysfunctional TCF1+PD-1- state, unresponsive to ICB.

Conclusions:

• Antigen specificity dictates tumor-reactive T-cell differentiation and fate.
• SSA-specific T cells adopt a dysfunctional TCF1+PD-1- phenotype, lacking effector function.
• These findings highlight distinct T-cell responses to TSA versus SSA, informing strategies to enhance anti-tumor immunity while mitigating autoimmunity.