title: Ciliary neurotrophic factor (CNTF) for human retinal degeneration: phase I trial of CNTF delivered by encapsulated cell intraocular implants.
abstract: Neurotrophic factors are agents with a promising ability to retard progression of neurodegenerative diseases and are effective in slowing photoreceptor degeneration in animal models of retinitis pigmentosa. Here we report a human clinical trial of a neurotrophic factor for retinal neurodegeneration. In this Phase I safety trial, human ciliary neurotrophic factor (CNTF) was delivered by cells transfected with the human CNTF gene and sequestered within capsules that were surgically implanted into the vitreous of the eye. The outer membrane of the encapsulated cell implant is semipermeable to allow CNTF to reach the retina. Ten participants received CNTF implants in one eye. When the implants were removed after 6 months, they contained viable cells with minimal cell loss and gave CNTF output at levels previously shown to be therapeutic for retinal degeneration in rcd1 dogs. Although the trial was not powered to form a judgment as to clinical efficacy, of seven eyes for which visual acuity could be tracked by conventional reading charts, three eyes reached and maintained improved acuities of 10-15 letters, equivalent to two- to three-line improvement on standard Snellen acuity charts. A surgically related choroidal detachment in one eye resulted in a transient acuity decrease that resolved with conservative management. This Phase I trial indicated that CNTF is safe for the human retina even with severely compromised photoreceptors. The approach to delivering therapeutic proteins to degenerating retinas using encapsulated cell implants may have application beyond disease caused by genetic mutations.
authors.affiliation: National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA. paulsieving@nei.nih.gov
authors.forename: Paul A
authors.initials: PA
authors.lastname: Sieving
authors.forename: Rafael C
authors.initials: RC
authors.lastname: Caruso
authors.forename: Weng
authors.initials: W
authors.lastname: Tao
authors.forename: Hanna R
authors.initials: HR
authors.lastname: Coleman
authors.forename: Darby J S
authors.initials: DJ
authors.lastname: Thompson
authors.forename: Keri R
authors.initials: KR
authors.lastname: Fullmer
authors.forename: Ronald A
authors.initials: RA
authors.lastname: Bush
mesh_terms: D000328:Adult; D000368:Aged; D002460:Cell Line; D020934:Ciliary Neurotrophic Factor / Q000008:administration & dosage* / Q000096:biosynthesis / Q000235:genetics / Q000627:therapeutic use; D015194:Diffusion Chambers, Culture; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000627:therapeutic use; D012162:Retinal Degeneration / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D012449:Safety; D014162:Transfection
chemical_list: D020934:Ciliary Neurotrophic Factor; D011994:Recombinant Proteins