Potent antitumor effect of tumor microenvironment‐targeted oncolytic adenovirus against desmoplastic pancreatic cancer

Pancreatic cancer is a leading cause of cancer‐related death. Desmoplastic pancreatic tumors exhibit excessive extracellular matrix (ECM) and are thus highly resistant to anticancer therapeutics, since the ECM restricts drug penetration and dispersion. Here, we designed and generated two hypoxia‐responsive and cancer‐specific hybrid promoters, H(mT)E and H(E)mT. Transgene expression driven by each hybrid promoter was markedly higher under hypoxic conditions than normoxic conditions. Moreover, H(E)mT‐driven transgene expression was highly cancer‐specific and was superior to that of H(mT)E‐driven expression. A decorin‐expressing oncolytic adenovirus (Ad; oH(E)mT‐DCN) replicating under the control of the H(E)mT promoter induced more potent and highly cancer‐specific cell death compared with its cognate control oncolytic Ad, which harbored the endogenous Ad E1A promoter. Moreover, oH(E)mT‐DCN exhibited enhanced antitumor efficacy compared with both the clinically approved oncolytic Ad ONYX‐015 and its cognate control oncolytic Ad lacking DCN. oH(E)mT‐DCN treatment also attenuated the expression of major ECM components, such as collagen I/III, elastin and fibronectin and induced tumor cell apoptosis, leading to extensive viral dispersion within orthotopic pancreatic tumors and pancreatic cancer patient‐derived tumor spheroids. Collectively, these findings demonstrate that oH(E)mT‐DCN exhibits potent antitumor efficacy by degrading the ECM and inducing apoptosis in a multifunctional process. This process facilitates the dispersion and replication of oncolytic Ad, making it an attractive candidate for the treatment of aggressive and desmoplastic pancreatic cancer.