Ciliary Neurotrophic Factor Drug Well-tolerated in MacTel Patients

CNTF therapy has transitioned from experimental trials to clinical practice as an approved therapeutic option for MacTel, but authors of a recent study suggest that further trials are required to fully assess its long-term efficacy. Photo: Eric Dillinger, OD. Click image to enlarge. The rare but serious condition macular telangiectasia (MacTel), a bilateral neurodegenerative disease characterized by neurosensory and macular capillary network atrophy, only recently gained FDA approval for a therapy—the drug Encelto from Neurotech Pharmaceuticals, comprised of ciliary neurotrophic factor (CNTF). A randomized clinical trial of a CNTF implant found that treated eyes experienced a slower progression of retinal degeneration in patients with MacTel type 2. To expand on this finding, researchers conducted a systematic review to assess the structural and functional outcomes.. They found that CNTF therapy appears to slow retinal degeneration and preserve visual function, but further trials are required to fully assess its long-term efficacy. These results were reported last week in Retina.Studies were retrieved from Medline, Embase and Cochrane Library databases. The primary outcome was final best-corrected visual acuity (BCVA) and changes from baseline, while ellipsoid zone (EZ) discontinuity area was a secondary outcome. Risk of bias for observational studies and randomized clinical trials were accounted for, according to the team’s paper on the work.Five studies reporting on 498 eyes of 422 patients were included. Overall, Encelto appears to slow the progression of retinal degeneration, specifically in terms of EZ discontinuity. While structural benefits are consistently identified, functional gains have been mixed. Some data indicate preserved reading speed in treated patients while other functional measures, such as BCVA and patient-reported outcomes, have not shown significant differences compared to sham-treated groups.One randomized-controlled trial of 99 eyes found decreased progression of retinal degeneration and reduced decline in reading speed in implant-treated eyes compared to sham-treated eyes. An uncontrolled Phase I safety trial demonstrated good tolerance, with no significant differences in visual acuity or retinal sensitivity between treated and untreated eyes over 36 months, though five participants experienced persistent miosis in the implanted eye. One study highlighted smaller changes in EZ defect areas in CNTF-treated eyes compared to sham-treated eyes. “OCT mapping of EZ discontinuity detects structural changes before mesopic microperimetry identifies retinal sensitivity loss in MacTel,” the authors wrote in their paper. “Using OCT to determine outcomes may prevent the potential exclusion of early defects or disease of the outer retina over mesopic function as a measure of retinal degeneration.”Reported adverse effects are typically limited to miosis and delayed dark adaptation, and there were no severe complications such as endophthalmitis, retinal breaks or detachments. Although MacTel is a bilateral disease, reporting outcomes and efficacy based on a sample of bilateral and unilateral eyes poses a risk of bias, the authors explained in their paper. “A more robust approach would involve using statistical techniques that account for inter-eye correlations. Furthermore, extending study duration beyond 24 months could reveal greater divergence in outcomes between CNTF-treated and sham-treated eyes. Future studies with extended follow-up would be invaluable in determining the sustained impact of CNTF therapy on disease progression.”This study did have limitations, the researchers acknowledged. Data synthesis was primarily narrative due to the heterogeneity of study designs and reporting methods, which also prevented a formal meta-analysis. Additionally, the authors highlight the need for further, long-term and larger-scale trials to better understand the therapy's long-term efficacy and its potential impact on other disease features, such as retinal cavitations and choroidal neovascularization.Click here for the journal source. Sriranganathan A, Rajesh Z, Mihalache A, et al. Ciliary neurotrophic factor therapy for macular telangiectasia type 2: a systemic review. Retina. April 9, 2026. [Epub ahead of print.] This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.