An oncolytic virus armed with fowl adenovirus fiber-modified recombinant TRAIL enhances tumor targeting and immunotherapy activity.

Oncolytic viruses have emerged as a promising strategy in cancer immunotherapy and have been applied to the treatment of various tumors. We previously demonstrated that oncolytic adenoviruses engineered expressing tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) could induce apoptosis in tumor cells and modulate immune responses in the tumor microenvironment. To enhance targeting capability and antitumor immunity, the full-length TRAIL is intended to be replaced with a soluble TRAIL (sTRAIL). However, the sTRAIL is limited by structural instability and hepatic accumulation. In this study, we performed an optimized design based on the previously developed, more stable sTRAIL (FA1FT) by fusing it with a knobless fiber motif derived from fowl adenovirus type 1. Through structural analysis and genetic engineering, we developed a novel recombinant sTRAIL protein (mut-FA1TLST) that exhibited reduced liver tropism and enhanced antitumor activity both in vitro and in vivo. Furthermore, we incorporated this optimized sTRAIL into a capsid-modified oncolytic adenovirus, which demonstrated improved tumor targeting ability and antitumor efficacy. The recombinant oncolytic virus expressing the sTRAIL also promoted activation of CD4⁺ T cells, CD8⁺ T cells and DCs in the tumor microenvironment, thereby eliciting antitumor immune response. Overall, this study provides a promising recombinant sTRAIL candidate for preclinical and clinical applications and presents a novel oncolytic virus with potential for in vivo tumor immunotherapy.