Immune System Modulation with Oral Vancomycin in combination with Stereotactic Body Radiotherapy (SBRT) for medically inoperable Early-Stage Non-small Cell Lung Cancer

We report the results of a randomized, open-label pilot study evaluating oral vancomycin combined with SBRT in early-stage non-small cell lung cancer. Building on prior research, vancomycin was found to enhance antitumor effects by modulating gut microbiota and boosting immune responses notably improving progression-free and overall survival (P.F.S. and O.S.). Patients treated with vancomycin (125 mg QID for 5 weeks starting one week before SBRT) showed increased expression of antigen presenation machinary in PBMCs and councurrent T-cell activation, and significant changes in gut microbiome composition and metabolite profiles, including reduced Short Chain Fatty Acids and elevated TNF-beta levels. With minimal adverse events, vancomycin appears to synergistically enhance RT-induced antitumor immunity, positioning it as a viable strategy for improving oncological outcomes. Further studies with larger cohorts are needed to confirm these results.