Point source concentration of GDNF may explain failure of phase II clinical trial

Michael Francis Salvatore, Yi Ai, Brent Fischer, Amanda M. Zhang, Richard C. Grondin, Zhiming Zhang, Greg A. Gerhardt, Don M. Gash

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158 Citations (Scopus)

Abstract

Significant differences have been reported in results from three clinical trials evaluating intraputamenal infusion of glial cell line-derived neurotrophic factor (GDNF) for the treatment of Parkinson's disease. To determine if problems in drug bioavailability could have contributed to the discrepancies between studies, we have analyzed the distribution of intraputamenally infused GDNF in the rhesus monkey brain using the delivery system and infusion protocol followed in a phase 2 clinical trial that failed to achieve its primary endpoint. I125-GDNF was unilaterally infused into the putamen of three adult rhesus monkeys for 7 days. Three age- and sex-matched animals received vehicle infusions following identical procedures. GDNF levels in the brain, peripheral organs, blood and CSF were quantified and mapped by GDNF immunocytochemistry, GDNF ELISAs and I125 measurements. Infused GDNF was found to be unevenly concentrated around the catheter, with tissue levels dropping exponentially with increasing distance from the point source of the single opening in the catheter tip. The volume of distribution of GDNF around the catheter, as determined by immunocytochemistry, varied over four-fold between animals ranging from 87 to 369 mm3. The concentration of GDNF around the catheter tip and limited diffusion into surrounding brain parenchyma support the hypothesis that drug bioavailability was limited to a small portion (2-9%) of the human putamen in the clinical trial using this catheter and infusion protocol.

Original languageEnglish
Pages (from-to)497-505
Number of pages9
JournalExperimental Neurology
Volume202
Issue number2
DOIs
StatePublished - 1 Dec 2006

Fingerprint

Glial Cell Line-Derived Neurotrophic Factor
Phase II Clinical Trials
Catheters
Putamen
Clinical Trials
Macaca mulatta
Biological Availability
Brain
Immunohistochemistry
Pharmaceutical Preparations
Parkinson Disease
Enzyme-Linked Immunosorbent Assay

Keywords

  • Clinical trial
  • Drug delivery
  • GDNF
  • Nonhuman primates
  • Putamen
  • Tissue levels

Cite this

Salvatore, Michael Francis ; Ai, Yi ; Fischer, Brent ; Zhang, Amanda M. ; Grondin, Richard C. ; Zhang, Zhiming ; Gerhardt, Greg A. ; Gash, Don M. / Point source concentration of GDNF may explain failure of phase II clinical trial. In: Experimental Neurology. 2006 ; Vol. 202, No. 2. pp. 497-505.
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Salvatore, MF, Ai, Y, Fischer, B, Zhang, AM, Grondin, RC, Zhang, Z, Gerhardt, GA & Gash, DM 2006, 'Point source concentration of GDNF may explain failure of phase II clinical trial', Experimental Neurology, vol. 202, no. 2, pp. 497-505. https://doi.org/10.1016/j.expneurol.2006.07.015

Point source concentration of GDNF may explain failure of phase II clinical trial. / Salvatore, Michael Francis; Ai, Yi; Fischer, Brent; Zhang, Amanda M.; Grondin, Richard C.; Zhang, Zhiming; Gerhardt, Greg A.; Gash, Don M.

In: Experimental Neurology, Vol. 202, No. 2, 01.12.2006, p. 497-505.

Research output: Contribution to journalArticleResearchpeer-review

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