An Epigenetic Nanoagonist Facilitates T Cell Priming, Recruitment, and Reinvigoration in Tumors Resistant to PD‐L1 Therapy

Inefficient priming, poor recruitment, and inadequate reinvigoration of T cells challenges the therapy of PD-L1-resistant tumors. Herein, a pH-responsive charge-reversal nanoplatform integrating coactivator-associated arginine methyltransferase 1 (CARM1) inhibitor (iCARM1) and poliovirus receptor siRNA (siPVR) is developed. Upon tumor penetration, iCARM1 released in tumor cells facilitates T cell priming by epigenetically activating cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling-mediated dendritic cell maturation. Meanwhile, in T cells, iCARM1 facilitates their recruitment by upregulating CXC-chemokine receptor 3 (CXCR3) expression. The released siPVR silences pvr to reinvigorate T cells. This epigenetic nanoagonist induces a robust immune response, dramatically suppresses tumor growth, metastasis, and relapse, and confers durable protection against secondary tumor challenge. Multiple PD-L1-resistant models demonstrate the broad applicability of this strategy. This study thus represents an innovative approach for facilitating multilevel T cell responses to combat PD-L1-resistant tumors.