Glial cell line–derived neurotrophic factor (GDNF) infused unilaterally into the putamen for 6 months has been previously shown to improve significantly motor functions and quality of life measures in 10 patients with Parkinson disease (PD) in a Phase I trial. In the present study the authors report the safety and efficacy of continuous treatment for a minimum of 1 year. After the trial was halted by the drug sponsor, the patients were monitored for an additional 1 year during which the effects of drug withdrawal were evaluated.
During the extended study period, patients received a 30-μg/day unilateral intraputamenal infusion of GDNF at a basal infusion rate supplemented with pulsed boluses every 6 hours at a convection-enhanced delivery rate to increase tissue penetration of the protein. When the study was stopped, the delivery system was reprogrammed to deliver sterile saline at the basal infusion rate of 2 μl/hour.
The Unified Parkinson's Disease Rating Scale (UPDRS) total scores after 1 year of therapy were improved by 42 and 38% in the off- and on-medication states; the motor UPDRS scores were also improved 45 and 39%, respectively. Benefits from treatment were lost by 9 to 12 months after the cessation of GDNF infusion. The UPDRS scores returned to their baseline and the patients required higher levels of conventional antiparkinsonian drugs to treat symptoms. After 11 months of treatment, the delivery system had to be removed in one patient because of risk of infection. Seven patients developed antibodies to GDNF but without evident clinical sequelae. There was no evidence for GDNF-induced cerebellar toxicity, as evaluated by magnetic resonance imaging and clinical testing.
The unilateral administration of GDNF results in significant, sustained bilateral benefits in patients with PD. These improvements are lost within 9 months of drug withdrawal. Safety concerns with GDNF therapy can be closely monitored and managed.
Abbreviations used in this paper:CAPSIT-PD = Core Assessment Program Surgical Intervention Therapies for Parkinson Disease; EOT = end of therapy; GDNF = glial cell line–derived neurotrophic factor; MR = magnetic resonance; PD = Parkinson disease; UPDRS = Unified Parkinson's Disease Rating Scale.
AiYCarterNZhangZGerhardtGAGashDM: Cerebellar histopathological analysis in normal and parkinsonian rhesus monkeys following chronic intracerebral infusion of GDNF. Soc Neurosci Abstracts2005. (Abstract)
ChebroluHSlevinJTGashDAGerhardtGAYoungBGivenCA: MRI volumetric and intensity analysis of the cerebellum in Parkinson's disease patients infused with glial-derived neurotrophic factor (GDNF). Exp Neurol198:450–4562006
EricsonCGeorgievskaBLundbergC: Ex vivo gene delivery of GDNF using primary astrocytes transduced with a lentiviral vector provides neuroprotection in a rat model of Parkinson's disease. Eur J Neurosci22:2755–27642005
SajadiABensadounJCSchneiderBLLo BiancoCAebischerP: Transient striatal delivery of GDNF via encapsulated cells leads to sustained behavioral improvement in a bilateral model of Parkinson disease. Neurobiol Dis22:119–1292005
SlevinJTGerhardtGASmithCDGashDMKryscioRYoungB: Improvement of bilateral motor functions in patients with Parkinson disease through the unilateral intraputaminal infusion of glial cell line-derived neurotrophic factor. J Neurosurg102:216–2222005