Qualitative Imaging of Adeno-Associated Virus Serotype 2-Human Aromatic L-Amino Acid Decarboxylase Gene Therapy in a Phase I Study for the Treatment of Parkinson Disease
ABSTRACT Putaminal convection-enhanced delivery (CED) of an adeno-associated virus serotype 2 (AAV2) vector, containing the human aromatic L-amino acid decarboxylase (hAADC) gene for the treatment of Parkinson disease (PD), has completed a phase I clinical trial.
To retrospectively analyze magnetic resonance imaging (MRI) and positron emission tomography (PET) data from the phase I trial, correlate those data with similar nonhuman primate (NHP) data, and present how such information may improve future PD gene therapy trials in preparation for the initiation of the phase II trial.
Ten patients with PD had been treated with bilateral MRI-guided putaminal infusions of AAV2-hAADC. MRI and PET scans were obtained at baseline (before vector administration) and at various intervals after treatment. Three normal adult NHPs received similar infusions into the thalamus. Imaging studies for both groups are presented, as well as hAADC immunohistochemistry for the NHPs.
Early post-CED MRI confirmed the stereotactic targeting accuracy and revealed T2 hyperintensity around the distal cannula tracts, best seen within 4 hours of surgery. Coregistration of post-CED MRI and PET scans revealed increased PET uptake at the sites of T2 hyperintensity. Similar T2 hyperintensities in NHP MRI correlated with hAADC immunohistochemistry.
Our analysis confirms the correct targeting of the CED cannula tracts within the target human putamen. Coregistration of MRI and PET confirms colocalization of T2 hyperintensities and increased PET uptake around the distal cannula tracts. Because PET uptake closely correlates with hAADC transgene expression and NHP data confirm this relationship between T2 hyperintensity and hAADC immunohistochemistry, we believe that T2-weighted MRI allows visualization of a significant part of the distribution volume of the hAADC gene therapy. Recommendations for future protocols based on these data are presented.
SourceAvailable from: Howard Federoff[Show abstract] [Hide abstract]
ABSTRACT: The pharmaceutical industry's development of therapeutic medications for the treatment of Parkinson's disease (PD) endures, as a result of the continuing need for better agents, and the increased clinical demand due to the aging population. Each new drug offers advantages and disadvantages to patients when compared to other medical offerings or surgical options. Deep brain stimulation (DBS) has become a standard surgical remedy for the effective treatment of select patients with PD, for whom most drug regimens have failed or become refractory. Similar to DBS as a surgical option, gene therapy for the treatment of PD is evolving as a future option. In the four different PD gene therapy approaches that have reached clinical trials investigators have documented an excellent safety profile associated with the stereotactic delivery, viral vectors and doses utilized, and transgenes expressed. In this article, we review the clinically relevant gene therapy strategies for the treatment of PD, concentrating on the published preclinical and clinical results, and the likely mechanisms involved. Based on these presentations, we advance an analysis of how the nature of the gene therapy used may eventually expand the scope and utility for the management of PD.Pharmaceuticals 12/2012; 5(6):553-590. DOI:10.3390/ph5060553
[Show abstract] [Hide abstract]
ABSTRACT: The existing treatment of Parkinson's disease (PD) is directed towards substituting dopamine loss with either dopamine replacement therapy or pharmacological therapies aimed at increasing dopamine at the synapse level. Emerging viable alternatives include the use of cell-based and gene-based therapeutics. In this review, we discuss efforts in developing in vitro and in vivo models and their translation to human clinical trials for gene-based therapy of this distressing and prevalent neurodegenerative disorder. Given the mismatch between expectations from preclinical data and results of human pivotal trials, drug delivery has been identified as the key emerging area for translational research due to limitation of limited efficacy. The chief highlights of the current topic include use of improved delivery methods of gene-based therapeutic agents. Convection-enhanced delivery (CED), an advanced infusion technique with demonstrated utility in ex vivo and in vivo animal models has recently been adopted for PD gene-based therapy trials. Several preclinical studies suggest that magnetic resonance imaging (MRI)-guided navigation for accurately targeting and real time monitoring viral vector delivery (rCED) in future clinical trials involving detection of gene expression and restoration of dopaminergic function loss using pro-drug approach will greatly enhance these PD treatments.Annals of Neurosciences 07/2012; 19(3):133-146. DOI:10.5214/ans.0972.7531.190310
[Show abstract] [Hide abstract]
ABSTRACT: Convection enhanced delivery (CED) is emerging as a promising infusion toolto facilitate delivery of therapeutic agents into the brain via mechanically controlled pumps. Infusion protocols and catheter design have an important impact on delivery. CED is a valid alternative for systemic administration of agents in clinical trials for cell and gene therapies. Where gel and ex vivo models are not sufficient in modeling the disease, in vivo models allow researchers to better understand the underlying mechanisms of neuron degeneration, which is helpful in finding novel approaches to control the process or reverse the progression. Determining the risks, benefits, and efficacy of new gene therapies introduced via CED will pave a way to enter human clinical trial.Annals of Neurosciences 07/2013; 20(3):108-114. DOI:10.5214/ans.0972.7531.200306