Background: To enhance the efficacy of adoptive NK cell therapy against solid tumors, NK cells must be modified to resist exhaustion in the tumor microenvironment (TME). However, the molecular checkpoint underlying NK cell exhaustion in the TME remains elusive.
Methods: We analyzed the correlation between TIPE2 expression and NK cell functional exhaustion in the TME both in humans and mice by single-cell transcriptomic analysis and by using gene reporter mice. We investigated the effects of TIPE2 deletion on adoptively transferred NK cell therapy against cancers by using NK cells from NK-specific Tipe2-deficient mice or peripheral blood-derived or induced pluripotent stem cell (iPSC)-derived human NK cells with TIPE2 deletion by CRISPR/Cas9. We also investigated the potential synergy of double deletion of TIPE2 and another checkpoint molecule, CISH.
Results: By single-cell transcriptomic analysis and by using gene reporter mice, we found that TIPE2 expression correlated with NK cell exhaustion in the TME both in humans and mice and that the TIPE2 high NK cell subset correlated with poorer survival of tumor patients. TIPE2 deletion promoted the antitumor activity of adoptively transferred mouse NK cells and adoptively transferred human NK cells, either derived from peripheral blood or differentiated from iPSCs. TIPE2 deletion rendered NK cells with elevated capacities for tumor infiltration and effector functions. TIPE2 deletion also synergized with CISH deletion to further improve antitumor activity in vivo.
Conclusions: This study highlighted TIPE2 targeting as a promising approach for enhancing adoptive NK cell therapy against solid tumors.
Keywords: immunotherapy, adoptive; killer cells, natural.
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