The data demonstrate that recombinant rLAS-uPA was capable of infecting a variety of uPAR-expressing canine brain tumors, generally well tolerated in tumor-bearing dogs, resulted in objective, neuroradiological tumor responses in 2/20 (10%) of the dogs enrolled in the study, and was associated with the rapid development of anti-rLAS-uPA neutralizing antibodies. The gene discussed is PLAU; the disease is brain neoplasm.