Nightstar Announces Phase 3 Trial for NSR-REP1 in Choroideremia Patients

After successful outcomes were observed during the Phase 1/2 clinical trials, Nightstar Therapeutics has announced the initiation of their STAR Phase 3 registrational trial evaluating the safety and efficacy of NSR-REP1, a therapy for choroideremia patients.

“The Choroideremia Research Foundation is encouraged by the advancement of this gene therapy and congratulates the Nightstar team for their unrelenting commitment to serving patients,” said Randy Wheelock, chief advisor for research and therapy development for the Choroideremia Research Foundation in a press release.

Choroideremia is a genetic condition causing degenerative vision loss, typically affecting males. During childhood, patients will experience impaired night vision, followed by the narrowing of tunnel vision and visual acuity. These vision problems are due to a loss of cells in the retina and choroid, and lead to complete blindness in adulthood.

The condition is caused by mutations in the CHM gene which is responsible for encoding REP1, a protein that plays a key role in intracellular protein trafficking and the elimination of waste from retinal cells. A lack of REP1 leads to the death of RPE cells and the degeneration of the retina.

While an estimated 50,000 people worldwide have choroideremia, there are currently no treatments available for the condition.

NSR-REP1 is a gene therapy that includes an AAV2 vector containing recombinant human complementary DNA that will replenish REP1 inside the eye, slowing the progression of choroideremia. The therapy is administered surgically by injection into the sub-retinal space between the outer layers of the retina. The therapy also has the potential of repairing already damaged retinal cells which would improve vision.

The FDA has previously granted orphan drug designation to Nightstar for NSR-REP1, as well as the European Medicines Agency, or the EMA.

The STAR trial will enroll 140 patients from 18 clinical sites in the United States, Europe, Canada and South America. The study participants will be divided into three cohorts based on the intensity of the dosage. Researchers will analyze the proportion of patients 12 months post-treatment with improvement of at least 15 ETDRS letters from baseline in visual acuity. Patients who received treatment will be compared to those who were assigned to the control group.

“The initiation of this first-ever Phase 3 trial for the treatment of choroideremia is a major milestone for Nightstar and a tremendous step forward for patients otherwise at risk of blindness due to this devastating disease,” said Dave Fellows, chief executive officer of Nightstar. “We are very encouraged by the responses we have seen to-date following treatment with NSR-REP1. This accomplishment demonstrates our team’s ability to successfully advance important gene therapies. We are thankful to our academic and advocacy partners, as well as the many patients who have participated in our studies, all of whom have been instrumental in helping us to achieve this milestone.”