Smart\nAccumulating Dual-Targeting Lipid Envelopes\nEquipping Oncolytic Adenovirus for Enhancing Cancer Gene Therapeutic\nEfficacy

Systemic delivery of oncolytic adenovirus\n(oAd) for cancer gene\ntherapy must overcome several limitations such as rapid clearance\nfrom the blood, nonspecific accumulation in the liver, and insufficient\ndelivery to the tumor tissues. In the present report, a tumor microenvironment-triggered\nartificial lipid envelope composed of a pH-responsive sulfamethazine-based\npolymer (PUSSM)-conjugated phospholipid (DOPE-HZ-PUSSM) and another\nlipid decorated with epidermal growth factor receptor (EGFR) targeting\npeptide (GE11) (GE11-DOPE) was utilized to encapsulate replication-incompetent\nAd (dAd) or oAd coexpressing short-hairpin RNA (shRNA) against Wnt5\n(shWnt5) and decorin (dAd/LP-GE-PS or oAd/LP-GE-PS, respectively).\nIn vitro studies demonstrated that dAd/LP-GE-PS transduced breast\ncancer cells in a pH-responsive and EGFR-specific manner, showing\na higher level of transduction than naked Ad under a mildly acidic\npH of 6.0 in EGFR-positive cell lines. In vivo biodistribution analyses\nrevealed that systemic administration of oAd/LP-GE-PS leads to a significantly\nhigher level of intratumoral virion accumulation compared to naked\noAd, oAd encapsulated in a liposome without PUSSM or EGFR targeting\npeptide moiety (oAd/LP), or oAd encapsulated in a liposome with EGFR\ntargeting peptide alone (oAd/LP-GE) in an EGFR overexpressing MDA-MB-468\nbreast tumor xenograft model, showing that both pH sensitivity and\nEGFR targeting ability were integral to effective systemic delivery\nof oAd. Further, systemic administration of all liposomal oAd formulations\n(oAd/LP, oAd/LP-GE, and oAd/LP-GE-PS) showed significantly attenuated\nhepatic accumulation of the virus compared to naked oAd. Collectively,\nour findings demonstrated that pH-sensitive and EGFR-targeted liposomal\nsystemic delivery of oAd can be a promising strategy to address the\nconventional limitations of oAd to effectively treat EGFR-positive\ncancer in a safe manner.