Pharmacological dopamine replacement therapies provide the most well-established treatments for Parkinson's disease (PD). However, these long-term treatments can lead to motor complications and off-target effects. ProSavin(®), a lentiviral vector (LV)-based gene therapy approach aimed at restoring local and continuous dopamine production, through delivery of three enzymes in the dopamine biosynthesis pathway, was demonstrated to be safe and well-tolerated in a phase I/II clinical study of patients with advanced PD. Although improvements in motor behaviour were observed, the data indicated that higher levels of dopamine replacement might be required to maximize benefit. We attempted to increase production of dopamine, and its precursor L-Dopa in LV-transduced cells, by optimizing the gene order in the ProSavin expression cassette, and by creating fusions of two or three of the transgenes, using linker sequences. In vitro analysis showed that several gene arrangements provided significantly increased dopamine and/or L-Dopa production compared with ProSavin, and that LV titers and transgene expression were not affected by introducing gene fusions. One vector, equine infectious anemia virus (EIAV)-TCiA, was selected for further characterization and showed significant improvements in dopamine and L-Dopa production compared with ProSavin, in human neuronal cells. Further characterization of EIAV-TCiA demonstrated expression of all three dopamine enzymes in vivo and faithful delivery and integration of the expected gene expression cassette within the genome of target cells, as assessed by Northern and Southern blotting. In conclusion, we have developed a novel LV vector with an increased capacity for L-Dopa and dopamine production compared with the current ProSavin vector. Clinical evaluation of this vector will be performed to assess the benefits in patients with PD.
Oncolytic VSV-IFNβ-NIS is selectively destructive to tumors. Here, we present the IND enabling preclinical rodent studies in support of clinical testing of vesicular stomatitis virus (VSV) as a systemic therapy. Efficacy studies showed dose-dependent tumor regression in C57BL/KaLwRij mice bearing syngeneic 5TGM1 plasmacytomas after systemic VSV administration. In contrast, the virus was effective at all doses tested against human KAS6/1 xenografts in SCID mice. Intravenous administration of VSV-mIFNβ-NIS is well tolerated in C57BL/6 mice up to 5 × 10(10) TCID50 (50% tissue culture infective dose)/kg with no neurovirulence, no cytokine storm, and no abnormalities in tissues. Dose-limiting toxicities included elevated transaminases, thrombocytopenia, and lymphopenia. Inactivated viral particles did not cause hepatic toxicity. Intravenously administered VSV was preferentially sequestered by macrophages in the spleen and liver. Quantitative RT-PCR analysis for total viral RNA on days 2, 7, 21, and 58 showed highest VSV RNA in day 2 samples; highest in spleen, liver, lung, lymph node, kidney, gonad, and bone marrow. No infectious virus was recovered from tissues at any time point. The no observable adverse event level and maximum tolerated dose of VSV-mIFNβ-NIS in C57BL/6 mice are 10(10) TCID50/kg and 5 × 10(10) TCID50/kg, respectively. Clinical translation of VSV-IFNβ-NIS is underway in companion dogs with cancer and in human patients with relapsed hematological malignancies and endometrial cancer.
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