Disease-modifying, multidimensional efficacy of putaminal CaV1.3-shRNA gene therapy in aged parkinsonism male and female macaques.

Abstract

There remain several unmet clinical needs in Parkinson's disease (PD) including waning and incomplete efficacy of symptomatic therapies, development of medication side effects (i.e., levodopa-induced dyskinesias [LID]) and unfettered disease progression. Ca_V1.3 calcium channels are therapeutic targets of intense interest in PD. We developed an RNA interference (RNAi)-based vector approach utilizing adeno-associated virus (AAV) expressing a short-hairpin (sh)RNA against Ca_V1.3 channels to provide potent, target-specific silencing of these channels that become dysfunctional in the parkinsonian striatum. We report here unprecedented evidence that magnetic resonance imaging-guided intraputaminal AAV-Ca_V1.3-shRNA in aged (25-29 years) male and female nonhuman primates with long-standing (8 months) advanced parkinsonian motor deficits results in a significant progressive reversal of functional deficits in the absence of pharmacotherapy, with some aspects including postural instability and motivation-based fine-motor performance returning to normal/pre-parkinsonian baseline. This contrasts maintenance of stable moderate-to-severe disability in those receiving the control/scrambled vector (AAV-SCR-shRNA). AAV-Ca_V1.3-shRNA recipients also demonstrate maintained levodopa motor benefit lost in these aged, parkinsonian subjects receiving the AAV-SCR-shRNA vector, similar to end-stage PD. Last, AAV-Ca_V1.3-shRNA recipients showed unprecedented, near-complete prevention of LID induction despite long-term (5.5 months), twice-daily, dose-escalation levodopa. The realization of these first-in-class multimodal gene therapy attributes in the clinic would represent a major therapeutic advancement for PD.