Methionine addiction in oral squamous cell carcinoma: a metabolic vulnerability targeted by engineered bacteria

Metabolic reprogramming is a defining hallmark of malignant transformation, and tumor-specific amino acid addiction has emerged as a promising therapeutic axis for precision oncology. Oral squamous cell carcinoma (OSCC) is an aggressive head and neck malignancy marked by limited curative options, frequent recurrence, and poor long-term survival. Cumulative multi-omics and clinical evidence consistently confirm widespread methionine addiction across OSCC lesions, yet conventional systemic methionine restriction strategies are hampered by severe off-target organ toxicity and insufficient tumor selectivity. Engineered attenuated Salmonella typhimurium strain SGN1 represents a tumor microenvironment-homing live biotherapeutic platform that achieves localized intratumoral methionine degradation with minimal systemic perturbation. Preclinical data across immunocompetent murine models and patient-derived organoids demonstrate robust anti-OSCC activity alongside controllable antibiotic-mediated clearance and broad systemic biosafety. This Commentary contextualizes SGN1 within the broader landscape of microbe-mediated amino acid depletion therapies, systematically dissects the core metabolic mechanisms underpinning OSCC methionine addiction, elaborates preclinical efficacy and safety profiles of SGN1, expands critical discussion of translational bottlenecks, and outlines structured clinical development frameworks for live bacterial metabolic therapeutics. By integrating comparative analysis of arginine and tryptophan-targeted microbial interventions, this work provides balanced, forward-looking insights to advance stratified, minimally invasive precision treatment for methionine-addicted OSCC and other solid tumors.