Gene Therapy Trial Results Released!

Robert E MacLaren In a letter published by the New England Journal of Medicine today, Dr. Robert Maclaren released positive long-term results from the initial 6 Choroideremia patients treated in the clinical trial at the University of Oxford. These results, which show sustained effects of gene therapy, represent another critical step toward the approval of gene therapy for Choroideremia.

The six-month results of this clinical trial were reported in the Lancet in 2014, and demonstrated improvement of vision in 2 patients with no change in vision of the remaining 4 patients. The results published today provided the continued evaluation of these 6 patients up to 3-4 years after treatment. The 2 patients whose visual acuity improved at six months demonstrated sustained effects of the treatment at approximately 3.5 years despite the continued loss of vision in the untreated eye during this period. 3 additional patients have maintained their visual acuity in the treated eye at 3-4 years despite declines in vision of the untreated eye. Patient 6, who received the lowest dose of gene therapy due to surgical issues, had continued decline of visual acuity in both eyes. In summary, 5 of 6 patients who received gene therapy have improved vision in their treated eye compared to the untreated eye after several years of observation.

“The CRF is thrilled to receive the results of Dr. Maclaren’s long-term observation of patients in his Choroideremia clinical trial,” reports Christopher Moen, CRF President. “These results show that gene therapy for Choroideremia is successful and has the potential to end blindness from this disease. These results bring us one step closer to the first approved treatment for Choroideremia, a treatment we have waited our whole lives for. We thank Dr. Maclaren and his team for their ground-breaking work on behalf of the Choroideremia community.”

Regarding these results, Dr. Maclaren states, “This shows that the visual acuity gains that were reported in the Lancet were real and also long-lasting. I think that is the key take-home message. The improved clarity is presumably due to the remaining cells in the central retina being healthier.” Dr. Maclaren will be presenting these results at the Association for Research in Vision and Ophthalmology Annual Meeting in Seattle, WA next week.

The gene therapy vector was developed by a team of researchers, led by Dr. Maclaren and Dr. Miguel Seabra, and is now the property of NighstaRx Ltd. The approach uses a virus known as adeno-associated virus (AAV) to deliver a normal copy of the gene causing Choroideremia into cells of the eye. The CRF provided significant financial support for the pre-clinical research and development of this gene therapy vector. Dr. Maclaren has completed his phase I/II trial involving a total of 12 patients and has announced the intention to proceed with a phase II study enrolling 30 patients later this year.
H Eric Hartman, CRF Executive Director, also noted his thanks to the CRF membership for their generous long-term support. “It is only through the dedication and generosity of our members and friends that enables the CRF to provide the crucial financial backing of for the amazing advancements in CHM research.”

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