Prospective manipulation of the gut microbiome with microbial ecosystem therapeutic 4 (MET4) in HPV-related locoregionally-advanced oropharyngeal cancer squamous cell carcinoma (LA-OPSCC) undergoing primary chemoradiation: ROMA2 study.

Background: Gut microbiome modulation to boost antitumor immune responses is under investigation.

Methods: ROMA-2 evaluated the microbial ecosystem therapeutic (MET)-4 oral consortia, a mixture of cultured human stool-derived immune-responsiveness associated bacteria, given with chemoradiation (CRT) in HPV-related oropharyngeal cancer patients. Co-primary endpoints were safety and changes in stool cumulative MET-4 taxa relative abundance (RA) by 16SRNA sequencing.