Largest Gene Therapy Trial for RP Completes Enrollment
Ocugen has finished enrolling patients for its Phase 3 trial of OCU400, a gene therapy for retinitis pigmentosa (RP). The company says it's the largest gene therapy trial ever for the condition and is on track to file for regulatory approval in Q3 2026.
Retinitis pigmentosa isn't a single disease but a group of inherited disorders caused by mutations in nearly 100 different genes, affecting about 1 in 4,000 people. This genetic diversity makes it challenging to develop treatments, as a therapy targeting one specific gene mutation would not work for others. OCU400 takes a different approach called "modifier gene therapy." Instead of replacing a patient's faulty gene, it uses a harmless adeno-associated virus (AAV) to deliver a functional copy of a master-regulator gene, NR2E3. This gene helps control a wide network of functions essential for retinal health, including photoreceptor development, metabolism, and cell survival. Because it targets a master-regulator gene, the therapy is "gene-agnostic," meaning it's designed to work regardless of the patient's specific mutation. This could be a major breakthrough, as the only currently FDA-approved gene therapy for RP targets a single rare gene, RPE65, leaving approximately 98% of patients without a treatment option. The Phase 3 "liMeliGhT" trial has enrolled 140 patients, including children as young as three. Patients are randomized 2:1, with two-thirds receiving the sub-retinal injection and one-third serving as an untreated control group. [
