Phase I/II Trial of Urokinase Plasminogen Activator-Targeted Oncolytic Newcastle Disease Virus for Canine Intracranial Tumors.

Simple Summary: Neurotropic oncolytic viruses have shown promise for the treatment of brain tumors, as they are naturally capable of entering the brain and selectively killing cancer cells. In this study, the safety, immunologic responses, and anti-tumor effects of intravenous administration of a genetically modified strain of neurotropic oncolytic Newcastle disease virus (NDV) to 20 dogs with spontaneously occurring brain cancers are characterized. Viral treatment was safe, with common side effects limited to transient low-grade fever, chills, and diarrhea. Anti-tumor responses, defined by a post-treatment reduction in tumor size as measured with brain MRI scans, were observed in two dogs. NDV genetic material was detectable in canine tumor tissue after treatment, confirming the ability of NDV to infect tumors. All dogs rapidly developed antibodies to NDV, suggesting that the viral dosing schedule may require modification to improve anti-tumor effects. Neurotropic oncolytic viruses are appealing agents to treat brain tumors as they penetrate the blood–brain barrier and induce preferential cytolysis of neoplastic cells. The pathobiological similarities between human and canine brain tumors make immunocompetent dogs with naturally occurring tumors attractive models for the study of oncolytic virotherapies. In this dose-escalation/expansion study, an engineered Lasota NDV strain targeting the urokinase plasminogen activator system (rLAS-uPA) was administered by repetitive intravenous infusions to 20 dogs with intracranial tumors with the objectives of characterizing toxicities, immunologic responses, and neuroradiological anti-tumor effects of the virus for up to 6 months following treatment. Dose-limiting toxicities manifested as fever, hematologic, and neurological adverse events, and the maximum tolerated dose (MTD) of rLAS-uPA was 2 × 107 pfu/mL. Mild adverse events, including transient infusion reactions, diarrhea, and fever were observed in 16/18 of dogs treated at or below MTD. No infectious virus was recoverable from body fluids. Neutralizing antibodies to rLAS-uPA were present in all dogs by 2 weeks post-treatment, and viral genetic material was detected in post-treatment tumors from six dogs. Tumor volumetric reductions occurred in 2/11 dogs receiving the MTD. Systemically administered rLAS-uPA NDV was safe and induced anti-tumor effects in canine brain tumors, although modifications to evade host anti-viral immunity are needed to optimize this novel therapy. [ABSTRACT FROM AUTHOR]