Pivotal Trial Results Announced for X-Linked Retinitis Pigmentosa Gene Therapy: Low-Light Vision Improves in Some Patients

For patients with X-linked retinitis pigmentosa, the gradual loss of photoreceptor cells makes seeing in dim environments increasingly difficult. On October 12, Beacon Therapeutics announced detailed results from the pivotal VISTA trial of its gene therapy laru-zova: some patients showed clear improvement on a low-light vision test one year after treatment. These data were presented at the American Academy of Ophthalmology annual meeting, providing new evidence for treating this inherited eye disease, but they do not mean the therapy has been approved for marketing.

VISTA is a randomized controlled Phase 2/3 trial that enrolled 85 males aged 12 to 48 with disease caused by RPGR gene variants. The high- and low-dose groups each included 29 participants, while another 27 received no treatment. At month 12, 31.0% and 24.1% of participants in the two treatment groups, respectively, identified at least 15 more letters on a low-luminance visual acuity test than at baseline; no participants in the control group met this threshold, and the differences between each treatment group and the control group were statistically significant. This represents improvement on a specific test and cannot be directly interpreted as restoration of normal vision.

The approach behind laru-zova is to deliver a functional copy of the RPGR gene into the retina to support the function of surviving photoreceptor cells. In an interview with *Retinal Physician*, trial investigator Robert A. Sisk explained that the therapy is delivered by subretinal injection, with the aim of covering the macula. Participant screening also had clearly defined criteria, including preservation of the photoreceptor-related ellipsoid zone on imaging, measurable responses on microperimetry, and stable fixation. These results therefore should not be directly generalized to patients with advanced disease who have already lost large numbers of photoreceptor cells.

Other measurements of visual function provided additional clues and a more nuanced picture of efficacy. Microperimetry data released by Beacon showed improvement in mean macular light sensitivity in the treatment groups compared with the control group; however, this comparison did not meet the conventional threshold for statistical significance in the high-dose group, while it did in the low-dose group. Results from different measurements should be interpreted separately: success on the primary endpoint cannot be extended to mean that all visual functions have been supported by evidence to the same degree.

The burden of treatment also includes surgery and postoperative care. Beacon said that two serious ocular adverse events occurred in the low-dose group, both attributed to surgery, and that the principal investigator determined they had resolved before the month 12 visit. Sisk also noted that about 30% of patients receiving prophylactic steroids developed elevated intraocular pressure; all cases in VISTA could be managed with topical pressure-lowering medication, and no patients underwent glaucoma surgery as a result. This information on intraocular pressure comes from an investigator interview and still needs to be assessed alongside the complete safety data.

The visual acuity gains after one year address whether patients may improve, but they do not yet answer how long that improvement can last. Sisk believes that further follow-up should also examine whether treatment helps preserve photoreceptor cells; this is a long-term treatment goal that cannot currently be established from one-year results alone. The publicly released data primarily come from a conference presentation, company announcements, and an investigator interview. A full study report will help further assess the robustness of the results.

Beacon plans to begin a rolling submission of its biologics license application later in 2026, submitting review materials in batches; a regulatory announcement issued the same day by investor Syncona also confirmed this timeline. Syncona holds an equity interest in Beacon, and its announcement can be used to cross-check the company's plans but does not constitute independent verification of efficacy. Moving from meeting trial endpoints to clinical use will still require regulatory review of efficacy, safety, and the overall application materials.