Efficacy of PD-1 blockade in cervical cancer is related to a CD8+FoxP3+CD25+ T-cell subset with operational effector functions despite high immune checkpoint levels.
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ABSTRACT: BACKGROUND:Cervical cancer (CxCa) is mainly a locally invading disease that metastasizes to loco-regional lymph node basins before involving distant organs in more advanced stages. Local immune potentiation of tumor-draining lymph nodes (TDLN) may thus protect against tumor progression. METHODS:To identify therapeutic targets for local immune modulation, multi-parameter flow cytometric T-cell profiling of primary cervical tumors (PT) and TDLN (n?=?37) was performed. The in-vitro effect of PD-1 blockade on T-cell reactivity to HPV16 E6 oncoproteins was determined in cultures of TDLN and PT single cell suspensions (n?=?19). Also, intracellular cytokine staining (ICS) upon anti-CD3 stimulation was performed in metastatic TDLN (LN+) and PT (n?=?7), as well as multiplexed immunofluorescence histochemistry staining (n?=?8). RESULTS:Our data revealed elevated rates of activated regulatory T cells (aTregs) and of central or effector memory CD8+ T cells in metastatic TDLN (LN+) as compared to tumor-free TDLN (LN-), and equally high or even higher rates of these subsets in PT. Both memory subsets co-expressed multiple immune checkpoints. PD-1 blockade significantly enhanced detectable E6-specific T-cell responses in 4/5 HPV16+ LN+ and in 1/5 HPV16+ PT. Whereas aTreg rates were higher in anti-PD-1 non-responders, in responders elevated levels of CD8+FoxP3+CD25+ T cells were observed, which correlated with the efficacy of PD-1 blockade (P?=?0.018). This subset was characterized by an early effector memory phenotype with particularly high levels of co-expressed PD-1, CTLA-4, TIM-3 and LAG-3 checkpoints, but, rather than exhausted, was shown upon polyclonal activation to produce higher levels of Granzyme-B and effector cytokines as compared to its CD8+FoxP3- counterparts. CONCLUSION:These observations support local PD-(L)1 blockade to interrupt loco-regional immune suppression in CxCa and control metastatic spread to TDLN. Furthermore, our data identify CD8+FoxP3+CD25+ T cells as therapeutic targets, which may also serve as predictive biomarker for PD-(L)1 checkpoint blockade.
SUBMITTER: Heeren AM
PROVIDER: S-EPMC6373123 | biostudies-literature | 2019 Feb
REPOSITORIES: biostudies-literature
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