Triadic Carrier-Free Nanomedicines: Natural Product-Based Nanoarchitectures for Cancer Therapy

Triadic carrier-free nanomedicines are an emerging class of anticancer nanoassemblies in which therapeutic efficacy derives solely from the self-assembly and/or prodrug behavior of natural-product building blocks, without exogenous carriers. This review systematically evaluates the design principles, assembly mechanisms, biological activities, pharmacokinetics, safety, and translational status of natural-product-based triadic systems composed of two phytochemicals and a third functional modulator (peptide, nucleic acid fragment, or secondary drug). We summarize current in vitro and in vivo evidence showing that preclinical studies on these triadic carrier-free nanomedicines have reported markedly enhanced cytotoxicity, improved tumor accumulation, and reduced off-target toxicity in selected models compared with free-drug mixtures or conventional nanocarriers. However, these benefits have so far been demonstrated in a limited range of tumor types and experimental conditions and require confirmation in broader, clinically oriented investigations. The novelty of this review lies in providing a focused framework that integrates molecular self-assembly forces, multistimuli responsiveness, and mechanistic crosstalk among three natural-product-derived components, while critically outlining key barriers to manufacturability, long-term biodistribution and toxicity, and regulatory pathways that must be addressed to advance triadic carrier-free nanomedicines toward human cancer therapy.