DNMT1 inhibition reprograms T cells to NK-like cells with potent antitumor effects

BCL11B ablation reprograms T cells into induced-T-to-NK cells (ITNKs). However, it remains unclear how BCL11B suppresses NK cell programs in T cells. Here, we demonstrate that the maintenance DNA methyltransferase DNMT1 interacts with BCL11B and safeguards the transition from T to NK-like cells. This involves a collective cooperation between DNMT1 and BCL11B that increases BCL11B protein stability and the fidelity of DNA methylation maintenance for NK cell-related genes, while also jointly suppressing NK cell programs in T cells. Moreover, DNMT1 maintains the epigenetic silencing of a distinct subset of NK cell-related genes independent of BCL11B. DNMT1 inhibitor (DNMT1i) or DNMT1 depletion reprograms T cells and chimeric antigen receptor (CAR) T cells into NK-like cells. These NK-like cells exhibit more robust antitumor effects than BCL11B-deficient ITNKs and parental CAR-T cells. Moreover, H3K27me3 synergizes with DNA methylation to repress NK cell-related pathways, and the combination of an EZH2 inhibitor (EZH2i) and DNMT1i potentiate both the reprogramming and cytotoxicity of NK-like cells. Our findings uncover the molecular mechanisms that safeguard T cell identity and provide a rationale for deriving NK-like cell sources with epigenetic inhibitors for cancer immunotherapy.