T-cell immunity in anti-tumor battle.

CD8+ T-cell exhaustion in tumors is linked to functional attrition and profound oligoclonality, shaped by clonal contraction under persistent antigen pressure in the tumor microenvironment.

• Why it matters: Tumor immune evasion limits the effectiveness of T-cell immunotherapies, and the field needs a clearer map of how antitumor T-cell diversity is narrowed during immune responses.
• What they did: This review synthesizes developmental and molecular mechanisms of CD4+ and mainly CD8+ lineages, including iterative selection, early thymic selection through primary priming to exhaustive differentiation, plus a structural model of fixed TCR repertoire constraints.
• The result: It proposes that tissue-resident memory can preserve functional clones and that immune checkpoint inhibition may, in some cases, enable durable benefit via systemic clonal replacement, informing next-generation strategies.

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