Abstract 2809: Bifidobacterium species BB_003 identified through metatranscriptomic analysis with experimentally validated antitumor actions

Abstract

Abstract Introduction & Objectives: A host's microbiome influences both gene expression and phenotype. Whole transcriptome sequencing (WTS) provides information about the microbiome in addition to gene expression. This research probes the correlation between microbial abundance, host gene transcription, and therapeutic efficacy, pinpointing a beneficial microbial strain and its mechanism of action. Materials & Methods: Bladder tissue biopsies from NMIBC patients underwent WTS and subsequent bioinformatic analysis. After in silico evaluation, in vitro assays including WST, quantitative PCR, and immune cell profiling were performed on mouse splenocytes. These assays were followed by in vivo assessment in both subcutaneous and orthotopic murine tumor models. Results: Among 59 biopsies, non-recurrence correlated with heightened presence of Lactococcus species LC_001 and Bifidobacterium species BB_003. Notably, BB_003 was associated with an extended recurrence-free survival (RFS). Gene set enrichment analysis (GSEA) implicated BB_003 in mediating a pro-inflammatory cascade, accentuating macrophages and interferons. In vitro WST assays showed the antitumor potential of BB_003_β, characterized by upregulated pro-inflammatory gene transcription. This strain increased effector CD8 T cells and M2 macrophages. In vivo, direct live BB_003_β introduction into subcutaneous tumors curtailed tumor proliferation. An increase in effector CD8 T cell populations within tumors and elevated cDC1 and M1 macrophage counts in tumor-draining lymph nodes were observed. Intravesical administration of live bacteria markedly decreased bladder weight, amplifying interferon alpha and beta gene expressions compared to controls. Conclusions: According to this study, BB_003_β inhibits tumor growth and is involved in immune response. Our study confirmed the antitumor properties of BB_003_β and suggested that cytokine and immune cell stimulation play a key role in its mechanism of action. Augmented insights warrant further exploration, particularly in synergy with intravesical BCG treatment. Citation Format: Xuan-Mei Piao, Kyungchan Min, Young Joon Byun, Chuang-Ming Zheng, Seon-Kyu Kim, Seong-Hwan Park, Sungmin Moon, Kyeong Kim, Ho Won Kang, Won Tae Kim, Seok Joong Yun, Hansoo Park. Bifidobacterium species BB_003 identified through metatranscriptomic analysis with experimentally validated antitumor actions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2809.