Potentiated antitumor effects of APS001F/5-FC combined with anti-PD-1 antibody in a CT26 syngeneic mouse model

ABSTRACT APS001F is a strain of Bifidobacterium longum genetically engineered to express cytosine deaminase that converts 5-fluorocytosine (5-FC) 5-fluorouracil. In the present study, antitumor effects plus 5-FC (APS001F/5-FC) in combination with anti-PD-1 monoclonal antibody were investigated using CT26 syngeneic mouse model. Both dosing APS001F/5-FC before and after mAb exhibited as well prolonged survival over nontreated control. The rate therapy significantly increased monotherapy mAb. Regulatory T cells among CD4+ tumor decreased therapy, while ratio CD8+ was maintained all groups. Taken these results together, not only demonstrates direct activity, but also immunomodulatory once localized hypoxic region tumor, which allows exert potentiated effects.