PLAU and central nervous system cancer: This trial provides in vivo data illustrating the ability of rLAS-uPA to infect a variety of canine intracranial tumors for which there exist human homologs, in vitro evidence of the fusogenicity and syncytia-forming ability of the rLAS-uPA in human and canine glioma cell lines, and also significant increases in serum IFN-α, TNF-α, and TRAIL cytokines in dogs following viral treatment.