Carrier-free Arg-CpG augments antitumor efficacy by triggering specific immune activation

The delivery of nucleic acids using nonviral vectors represents a promising approach for cancer therapy. Nevertheless, nucleic acid–based drugs suffer from poor potency and rapid degradation. Herein, we report a carrier-free nucleic acid delivery system termed Arg-CpG, which is easily constructed through charge-driven assembly of poly( l -arginine) (Arg) and the immune adjuvant unmethylated cytosine-phosphate-guanine oligonucleotide (CpG). This Arg-CpG functions as both a carrier and a therapeutic agent, thereby eliminating the need for a conventional drug delivery vehicle and minimizing potential toxicity. The guanidinium groups of Arg endow Arg-CpG with dual functionalities: enhancing cellular uptake and serving as the nitrogen donor for iNOS-mediated nitric oxide (NO) generation. This NO production further synergizes with CpG to drive macrophage reprogramming toward an antitumor phenotype. Notably, Arg-CpG exhibits cell-type–dependent modulation of autophagy. It disrupts autophagic machinery in 4T1 tumor cells while preserving functional autophagy in RAW264.7 macrophages. This differential activity results in selective killing of tumor cells without compromising the viability or function of normal immune cells. Consequently, Arg-CpG elicits a robust antitumor immune response in vivo. Moreover, the modular design of Arg-CpG enables its straightforward assembly with CpG oligonucleotides and other nucleic acid payloads (e.g., anti-miR oligonucleotides and siRNA), establishing a versatile and promising platform for nucleic acid–based cancer therapy.