New choroideremia gene therapy clinical trial

Researchers at the University of Pennsylvania are to begin the first US clinical trial of gene therapy for choroideremia.

The trial will take place at The Children’s Hospital of Philadelphia and is backed by Spark Therapeutics, a US gene therapy company.

Choroideremia is a rare inherited cause of severe sight loss that only affects the male population. Symptoms start in childhood with trouble seeing at night and eventually lead to complete blindness by around the age of 40. There is currently no treatment.

Promising UK Phase I trial

The world’s first clinical trial of gene therapy for choroideremia took place in the UK following initial work supported by the Tommy Salisbury Choroideremia Fund at Fight for Sight. The funds enabled researchers at Imperial College London to identify the function of the CHM gene, which is mutated in choroideremia, and was a necessary step in the process of developing the therapy. Results from the promising Phase I trial were reported in 2014.

The new US trial will target the same gene – CHM – with the aims of 1) testing the treatment’s safety and 2) finding the right dose to improve vision or prevent further sight loss.

“This is excellent news,” said Dr Dolores M Conroy, Director of Research at Fight for Sight. “The same adeno-associated virus technique had been used by Spark in successful gene therapy trials for Leber’s congenital amaurosis, now in Phase III. We very much look forward to their results on choroideremia.”