Recombinant Molecules as a New Frontier in Mucositis Therapy.

Mucositis significantly impairs patients' quality of life, and despite its clinical importance and the availability of symptomatic treatments, no gold-standard therapeutic protocol has been established. Recent advances in biotechnology and molecular biology have enabled the development of genetically engineered probiotic strains capable of producing or delivering therapeutic molecules directly to inflamed mucosal sites. Although several recombinant biotherapeutic bacteria have advanced to clinical evaluation, most have not yet reproduced the efficacy observed in preclinical models, and no products have yet been commercially approved for human use. This is the first review to comprehensively outline the recombinant molecules as an innovative biotherapeutic option for mucosal inflammation induced by chemoradiotherapy. In this review, we describe how genetically modified bacteria function as living drug delivery platforms, focusing on their ability to produce or deliver recombinant molecules, including antimicrobial peptides, antioxidant enzymes, growth factors, and interleukin receptor antagonists, for mucositis therapy. We further discuss key limitations, including biosafety, control of gene expression, and gut protection levels, while outlining future challenges.