NT-501 (Neurotech Pharmaceuticals, Inc., Lincoln, RI) slowed the loss of vision and increased retinal thickness in a phase 2 clinical trial in patients with dry age-related macular degeneration (AMD) involving geographic atrophy (GA), according to a company news release. NT-501 is an intraocular implant that consists of human cells that have been genetically modified to secrete ciliary neurotrophic factor (CNTF).
In the multicentered, randomized, double-masked, sham-controlled study, 51 patients with GA received either a high or low dose NT-501 implant or a sham treatment in one eye only and were assessed for changes in best corrected visual acuity. The study found that the high dose of NT-501 stabilized BCVA at 12 months. Of patients treated with the high dose, 96.3% (P=.078) lost fewer than 15 letters compared with 75% of patients in the sham-treatment group. It was hypothesized that no increase was observed in BCVA due to existing photoreceptor damage.
As early as 4 months after implantation of NT-501, optical coherence tomography (OCT) showed a statistically significant increase in retinal thickness for the high dose (P<.001) and the low dose (P=.013). This structural change is consistent with preclinical studies of NT-501 in which CNTF was shown to increase the thickness of the retina and the outer nuclear layer of photoreceptors, the news release said.
Additionally, no serious adverse events were reported, and both NT-501 and the surgical procedure were reportedly well tolerated. Five devices from this trial have been explanted 12 months after implantation, and all devices have been found to have uniformly healthy, viable cells that continue to produce therapeutic levels of CNTF, according to the news release.
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