Postbiotics, considered the functional successors of live probiotics, retain most of probiotics’ structural and/or bioactive properties, and are key mediators of probiotic–environment interactions. Beyond influencing tumor proliferation, metastasis, and immune regulation, postbiotics can enhance the effectiveness of current anti-cancer treatments. Postbiotic-based cancer therapy represents an advanced evolution of bacterial treatment with improved safety and treatment potential. However, the field is limited by postbiotics’ imprecise definition and lack of standardized manufacturing methods, which together hinder their clinical application. Here, we establish a systematic classification of postbiotics based on their formation processes, focusing on the complex mechanisms underlying their activity in anti-tumor therapy, their therapeutic promise, and their current clinical use and challenges. Our aim is to guide future research, translation, and industrial development.

Developing multifunctional nanoparticles to support new therapy models is a promising and challenging task to address the current dilemma on antitumor treatment. Herein, we incorporated multifunctional dendritic nanoparticles into a poly(D, L-lactide-co-glycolide)-poly(ethylene glycol)-poly(D, L-lactide-co-glycolide) (PLGA-PEG-PLGA) triblock copolymers thermosensitive injectable hydrogel matrix to construct a localized drug delivery system for combining chemotherapy and immunotherapy. The multifunctional dendritic nanoparticles were designed with following expectations: i, Dendritic scaffolds provide a hydrophobic interior to load the anticancer drug, doxorubicin (DOX), for chemotherapy; and ii, dendritic scaffolds are used to build arginine-rich molecules to provide the inducible nitric oxide synthase (iNOS) substrate, L-Arg, to M1 macrophages, which can produce the cytotoxic substance nitric oxide (NO) and subsequently induce tumor cell destruction through immunotherapy. It is noteworthy that the dendritic nanoparticles-in-hydrogel delivery system is able to gel at physiological temperature and serves as a warehouse for the sustained release of the drug. Ultimately, this system showed great efficacy in treating 4T1 cells-xenografted BALB/C mice (86.62% tumor growth inhibition). Therefore, this localized drug delivery system combining chemotherapy and immunotherapy provides a novel approach for cancer therapy.