E3LΔ83N-TK + hFlt3L + anti-muCTLA-4

E3LΔ83N-TK + hFlt3L + anti-muCTLA-4 is an experimental oncolytic virus-based immunotherapy regimen. It utilizes a modified Western Reserve strain of the vaccinia virus, specifically the E3LΔ83N-TK− mutant, which is attenuated through a deletion in the Z-DNA-binding domain of the E3L gene and the thymidine kinase (TK) gene. This viral vector is engineered to express two therapeutic payloads: human FMS-like tyrosine kinase 3 ligand (hFlt3L), which promotes the expansion and activation of dendritic cells, and a murine anti-CTLA-4 antibody (anti-muCTLA-4), which blocks the CTLA-4 immune checkpoint to enhance T-cell mediated anti-tumor responses. Developed by researchers at Memorial Sloan Kettering Cancer Center, this combination is designed for intratumoral delivery to stimulate both local and systemic (abscopal) anti-tumor immunity in solid tumors such as melanoma.