A Tumor-Activatable DNA Nanoengager That Orchestrates NK Receptor Clustering and Immune Checkpoint Blockage to Enhance Antitumor Cytotoxicity

Abstract Natural killer cell engagers (NKCEs) are promising immunotherapeutic agents for cancer treatment. However, their efficacy against solid tumors is severely limited by immune evasion mechanisms (mediated by the sialic acid–Siglec axis and PD-1/PD-L1 pathway), along with poor pharmacokinetics and off-target effects. Harnessing the precision and addressability of DNA origami, we engineered a tissue-specific, DNA origami-based, dual checkpoint-inhibiting NK synapse engager. This nanoplatform adopts a bilayered barrel architecture: the inner layer is functionalized with aNKp46, aPD-L1, and sialidase, while the outer layer is modified with the serum albumin-binding peptide ABD035 and a pH-sensitive i-motif switch. In the acidic tumor microenvironment, the DNA nanoengager undergoes specific dissociation of the outer protective layer, exposing the functional modules. These components concurrently bridge and activate NK cells, block the PD-L1 immune checkpoint, and specifically degrade tumor surface sialic acids, thereby reversing dual immunosuppression. This integrated DNA system enables synergistic integration of targeted activation, dual checkpoint blockade, and tumor microenvironment responsiveness, providing a novel smart nanoscale strategy to overcome multifaceted immune evasion in solid tumors and enhance the safety and efficacy of NK cell-based immunotherapy.