Commensal Clostridiales strains mediate effective anti-cancer immune response against solid tumors

Montalban-Arques A, Katkeviciute E, Busenhart P, Bircher A, Wirbel J, Zeller G, Morsy Y, Borsig L, Glaus Garzon JF, Muller A, Arnold IC, Artola-Boran M, Krauthammer M, Sintsova A, Zamboni N, Leventhal GE, Berchtold L, de Wouters T, Rogler G, Baebler K, Schwarzfischer M, Hering L, Olivares-Rivas I, Atrott K, Gottier C, Lang S, Boyman O, Fritsch R, Manz MG, Spalinger MR, Scharl M, Cell Host Microbe 29 (10) :1573-1588.e7 (2021).

Abstract

Despite overall success, T cell checkpoint inhibitors for cancer treatment are still only efficient in a minority of patients. Recently, intestinal microbiota was found to critically modulate anti-cancer immunity and therapy response. Here, we identify Clostridiales members of the gut microbiota associated with a lower tumor burden in mouse models of colorectal cancer (CRC). Interestingly, these commensal species are also significantly reduced in CRC patients compared with healthy controls. Oral application of a mix of four Clostridiales strains (CC4) in mice prevented and even successfully treated CRC as stand-alone therapy. This effect depended on intratumoral infiltration and activation of CD8(+) T cells. Single application of Roseburia intestinalis or Anaerostipes caccae was even more effective than CC4. In a direct comparison, the CC4 mix supplementation outperformed anti-PD-1 therapy in mouse models of CRC and melanoma. Our findings provide a strong preclinical foundation for exploring gut bacteria as novel stand-alone therapy against solid tumors.