salivarius REN or its secretions demonstrated significant efficacy in suppressing 4NQO-induced oral carcinogenesis, both in the initial and post-initial stages, and this inhibition showed a dose-dependent relationship.257 Gao et al.258 confirmed that the administration of Lactobacillus rhamnosus Probio-M9 significantly improved tumor inhibition by enhancing the efficacy and responsiveness of anti-PD-1-based immunotherapy. This evidence concerns the gene PDCD1 and neoplasm.