Impaired antitumor response to anti–PD-L1 treatment and significantly larger tumor in mice receiving probiotics compared with control mice. Significantly reduced frequency of interferon-γ (IFN-γ) positive CD8+ T cells in tumors of probiotic-treated mice versus controls. A trend toward fewer IFN-g CD4+ T helper 1 (TH1) cells in tumors from mice receiving probiotics versus control. This evidence concerns the gene CD4 and neoplasm.