GM-CSF and IL-21-armed oncolytic vaccinia virus significantly enhances anti-tumor activity and synergizes with anti-PD1 immunotherapy in pancreatic cancer.

Pancreatic cancer is one of the most aggressive cancers and poses significant challenges to current therapies because of its complex immunosuppressive tumor microenvironment (TME). Oncolytic viruses armed with immunoregulatory molecules are promising strategies to overcome limited efficacy and target inaccessible and metastatic tumors. In this study, we constructed a tumor-selective vaccinia virus (VV) with deletions of the TK and A49 genes (VVLΔTKΔA49, VVL-DD) using CRISPR-Cas9-based homologous recombination.