Table 1.

Overview of oncolytic vaccinia mechanisms of action

Mechanism of action	Preclinical	Clinical	References
Oncolysis	– Selective infection and killing of tumor cells demonstrated in vitro and in vivo	– Selective infection of tumor cells following intratumoral administration or intravenous infusion	Breitbach et al;17 Kim et al;2 Parato et al;5 Park et al18
Active immunotherapy	– Protective antitumor immunity induced – Complement-dependent cytotoxicity demonstrated; serum transfer exhibits antitumor activity in virus naïve rabbits	– Inflammatory response detected in tumors – Complement-dependent cytotoxicity demonstrated in patient serum from Phase I and Phase II trials	Heo et al;26 Hwang et al;24 Kim et al;25 Kirn et al;22 Mastrangelo et al23
Antivascular	– VEGF and FGF-2 driven infection of endothelial cells – I nfection of tumor-associated vasculature in vivo – Functional reduction in tumor blood flow	– Infection of tumor-associated endothelial cells – Acute reduction in tumor perfusion detected by dynamic magnetic resonance imaging	Breitbach et al27

Abbreviations: FGF-2, fibroblast growth factor 2; VEGF, vascular endothelial growth factor.