New surgical techniques offer improvements in the precision and safety of gene and cell therapy delivery to target tissue.
This article was reviewed by Allen C. Ho, MD, and M. Ali Khan, MD
Gene therapy is happening today and cell therapy may soon follow, according to Allen C. Ho, MD.
Dr. Ho, professor of ophthalmology, Thomas Jefferson University, and director of retina research, Mid Atlantic Retina and Wills Eye Hospital, Philadelphia, and his colleagues have been focusing on improving the consistency and precision of therapeutic delivery to target tissues.
“Subretinal delivery provides direct surgical access to target retinal pigment epithelial cells and retinal photoreceptors,” he said. “This direct access may be important for gene and cell therapies for treating retinal diseases.”
The first FDA-approved gene therapy is voretigene (Luxturna, Spark Therapeutics) for biallelic RPE65 mutation-associated retinal dystrophy. In addition to restoring vision to patients, the studies evaluating the efficacy of voretigene (among other gene therapy studies) have established the safety and feasibility of subretinal delivery of gene therapy.
According to Dr. Ho, translational scientists are working on improving viral capsids and transgene selections to improve efficacy. In this aim, Dr. Ho and colleagues are hoping to improve the consistency and precision of delivery systems for gene and cell therapy.
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Methods of drug delivery
Subretinal delivery is achieved in a few ways, the most familiar of these is “transretinal” via pars plana vitrectomy (PPV) and retinotomy using a microcatheter.
Another approach is subretinal delivery via the suprachoroidal space.
In this method, Dr. Ho explained, a flexible microcatheter follows the curvature of the sclera and a microneedle, which is under the visual control of the surgeon, enters the subretinal space without the need for a PPV and retinotomy.
“A new intriguing way of transfecting target tissue is suprachoroidal injection therapy,” he said. A major advantage of such a treatment would be the potential ability to perform the procedure in the office setting.