BCVA may be viable primary outcome in gene therapy trials for choroideremia
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Best corrected visual acuity was sustained or improved in patients with choroideremia who underwent gene therapy in a phase 2 study, and the researchers suggest that BCVA may be a viable primary outcome in advanced cases.
Byron L. Lam, MD, and colleagues at Bascom Palmer Eye Institute administered a high dose of AAV2-REP1 (Nightstar Therapeutics) as a subfoveal injection in six men with genetically confirmed advanced choroideremia. REP1, or Rab escort protein 1, is a CHM gene product that is absent in choroideremia.
Intraoperative microscope-integrated OCT was used to guide the injections, as well as monitor the procedure. The fellow eye was used as control.
Although no serious adverse events occurred, conjunctival hemorrhage, anterior chamber cells, vitreous cells, subretinal fluid and cataract were reported and were attributable to being likely caused by vitrectomy and subretinal fluid injection surgery.
At month 24, one patient had a 10 letter gain and another had a five letter gain; BCVA remained stable in the remaining four patients.
“We noted no significant BCVA improvement over time in any of the untreated eyes, indicating that improvement in BCVA could be used as a viable primary outcome for future choroideremia gene therapy trials for patients with advanced choroideremia,” the authors wrote. – by Patricia Nale, ELS
Disclosures: Lam reports affiliations with National Eye Institute, AGTC, Astellas, Editas, Envision, Nightstar, Quark, Sanofi, Second Sight Medical Products, Ionis, Shire, Spark and Allergan. Please see the study for all other authors’ relevant financial disclosures.