Won et al. reported that reducible poly (oligo-D-arginine) (rPOA) could deliver plasmid encoding herpes simplex virus-thymidine kinase (pHSV-TK)and demonstrated that locally injected rPOA/pHSV-TK with systemically administered GCV significantly reduced tumor volume and improved locomotor function compared to the GCV only group and naked pHSV-TK with GCV-treated group [12,13]. Here, TKT is linked to neoplasm.