Nightstar Therapeutics will begin a phase 2/3 expansion study of its gene therapy candidate for X-linked retinitis pigmentosa, according to a press release.
Designed to evaluate the safety and efficacy of NSR-RPGR in patients with X-linked retinitis pigmentosa due to RPGR mutations, the study will evaluate changes in retinal sensitivity following treatment, the release said.
It will include approximately 45 patients in six U.S. and U.K. surgical centers who have functional impairment as measured by microperimetry and the presence of viable photoreceptors.
Three randomized study arms will be included: a high-dose group (2.5 × 10^11 genome particles), a low-dose group (5 × 10^10 genome particles) and a group receiving no treatment.
“The modified phase 2/3 expansion study is designed to be consistent with recommendations in FDA’s draft guidance on the development of gene therapy products for retinal disorders, which we believe will allow us to expedite the development of NSR-RPGR,” Nightstar CEO Dave Fellows said in the release.
The study is expected to begin by the end of this year, with preliminary efficacy data expected in mid-2019 and 1-year follow-up data expected in 2020.