The Microbiome in Melanoma Progression and Therapy: Current Evidence and Emerging Biotherapeutic Strategies

Melanoma is driven by the complex interactions between tumor, host immunity, and the microbial communities present in the skin and gut. Increasing evidence accumulated over the past decade or so associates the composition of microflora with the outcome of melanoma therapy. Unveiling the complex network of microbiota in defining host response to tumor progression illuminates the prospect of microbiota modulation as a strategy for augmenting antitumor therapy. In this backdrop, the review comprehends the evidence connecting the skin–gut microbiome to the development, progression, and response to melanoma targeted chemotherapy and immunotherapy. It further assesses emerging microbiome-directed strategies, including dietary interventions, prebiotics, fecal microbiota transplantation, and engineered bacteria-based therapies, in conjunction with precision therapeutics. While experimental and early clinical findings indicate potential therapeutic opportunities, the evidence is predominantly associative, heterogeneous, or derived from preclinical studies. Future endeavours should aim to include larger and more diverse patient groups over time and profile microbial dynamics alongside tumor characteristics and immune responses.