Our study provides important evidence demonstrating that intrastriatal with or without intranigral gene delivery of the trophic factor NRTN (CERE120) to patients with advanced Parkinson’s disease can provide long-lasting (8–10 years) persistence of recombinant genomes with long-lasting transgene expression in putamen and substantia nigra with terminal sprouting, and focal areas of robust TH expression. The gene discussed is TH; the disease is Parkinson disease.