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Thierry Bordet, Karine Bigot, Elodie Touchard, Romain Benard, Jean-Denis Laffitte, Ronald BUGGAGE, Francine F Behar-Cohen; Repeated plasmid electrotransfection into the ciliary muscle allows for fine-tuning of intraocular protein levels. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2913. doi: https://doi.org/.
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Direct intravitreal (IVT) injections of drugs is now the standard-of-care for the treatment of retinal disorders. However, the need for repeated IVT injections to maintain adequate intraocular drug concentrations raises compliance and safety concerns. To overcome such concerns, we have developed a non-viral gene therapy strategy based on the electrotransfection (ET) of the ciliary muscle (CM) which serves as a biofactory for sustained production of secreted therapeutic proteins in the eye. Herein, we present safety and pharmacokinetic results following multiple site or repeated plasmid ET in the rabbit CM.
New Zealand White rabbits were treated with 1 to 4 intraCM injections and ET of EYS606 (a DNA plasmid coding for a potent soluble TNF-areceptor), corresponding to total doses of 75 to 300 µg/eye. EYS606 protein (Protein 6) levels were measured for up to 2 months in the vitreous (n = 4 eyes/time point). In a second study, 52 rabbits received repeated intraCM administrations and ET of pEYS606 (150 µg/eye) or vehicle on Days 1, 30 and 60. Safety, plasmid biodistribution and toxicokinetics were recorded on Days 6, 35, 65 and 6 months after the third ET.
Maximal Protein 6 levels (Cmax) were measured in the vitreous 5 days after plasmid ET. Increasing the number of intraCM injections and ET sites (up to 4 in the same eye) led to a linear increase in Cmax and AUC, and significantly increased the duration of Protein 6 exposure with half-lives up to 23.8 days. Repeated administration of EYS606did not cause any adverse ocular effects. Plasmid biodistribution after repeated ET was similar to the observed after a single ET with maximum copy number measured in the CM, increasing after each repeated ET and persisting over the 6-month follow-up period. EYS606 was only sporadically and transiently quantified in peripheral tissues. Repeating EYS606 administration maintained Protein 6 expression for a long period of time despite the development of anti-Protein 6 antibodies in rabbits.
These studies demonstrate that a non-viral gene therapy based on the ET of plasmids into the CM can be fine-tuned to control the levels and duration of transgene expression allowing protein levels to be tailored to the therapeutic need. These results also demonstrate the safety of repeated ET of the CM supportingreadministration regimens in future clinical studies.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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