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Emily Y. Chew, Traci E Clemons, Glenn J Jaffe, Sina Farsiu, eleonora lad, Martin Friedlander; Phase 2 Trial of Ciliary Neurotrophic Factor for Macular Telangiectasia Type 2. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2605. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Macular telangiectasia type 2 (MacTel), a bilateral neurodegenerative retinal disease that leads to marked deficits in near visual function, has no proven effective therapy. We tested whether encapsulated cell-based intravitreal sustained delivery of human ciliary neurotrophicfactor (CNTF) in an implant surgically placed in the vitreous provided a benefit for this condition.
This multi-center, single-masked sham-controlled study in 11 clinical sites in the United States and Australia enrolled participants with Mac Tel type 2. One eye of bilateral eligible participants received the implant of CNTF while the fellow eye had sham treatment. Pariticpants with unilaterl eligible eye were randomized to treatment or sham. The primary outcome was the difference in the area of neurodegeneration or the ellipzoid zone (EZ) loss at 24 months from baseline. Functional changes include microperimetry, and reading speed.
The study population of 67 participants (99 eyes) was mostly white, 61% were women, and the median age was 62 years (range 44-79 years). The mean best corrected visual acuity at baseline of 20/30. Two deaths occurred during the study. All surviving participants were followed to the final 24-month study visit. Eyes receiving the sham treatment had 31% greater progression of neurodegeneration than the CNTF-treated eyes, the difference in mean area of photoreceptor loss was 0.05 ± 0.03 mm2 (p=0.039) at 24 months. Retinal sensitivity changes, measured using microperimetry, a visual field test, were highly correlated with the changes in the area of photoreceptor loss (r = 0.86, p <0.0001). The mean retinal sensitivity loss of the sham group was 45% greater than the treated. As expected, there was no change in visual acuity between the treatment groups. However, there was a stabilization of the reading speed in the treated eyes while the sham eyes continued to experience reduced reading speed (p=0.016) at month 24 compared with baseline.
CNTF treatment delivered by NT501 was safe and well tolerated. CNTF had a beneficial effect and reduced the progressive loss of photoreceptors compared to untreated eyes. This is the first clinical trial to demonstrate that a neuroprotective agent that hasthe potential to slow progressive retinal neurodegeneration in MacTel. These results are sufficiently encouraging to support future phase 3 studies in Mac Tel type 2.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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