Spark Therapeutics, Inc. announced it has initiated enrollment of a Phase 1/2 clinical trial of its product candidate, SPK-CHM, for patients with choroideremia (CHM). CHM is an X-linked inherited retinal dystrophy which manifests in affected males in childhood as night blindness and a reduction of visual field, followed by progressive constriction of visual field, ultimately leading to complete blindness. The disease is characterized by deletions or mutations in the CHM gene, resulting in defective, or absent, Rab escort protein-1 (REP-1).

CHM affects an estimated 12,500 males in the United States and the five major European markets and there is currently no approved pharmacologic treatment for the disease. With SPK-CHM, Spark is leveraging the experience and technology utilized in the development of its lead Phase 3 program, SPK-RPE65, including the same vector, target cells and route of administration, as well as the same manufacturing process. The Phase 1/2 trial is an open-label, dose-escalating trial designed to assess the safety and preliminary efficacy of sub-retinal administration of SPK-CHM.

Spark currently plans to enroll up to 10 patients afflicted with the CHM genetic mutation. In addition to evaluating safety, the trial will help define the dose required to achieve stable or improved visual function and identify appropriate endpoints for subsequent clinical trials. In preclinical studies conducted in collaboration with Jean Bennett, M.D., Ph.D., the F.M. Kirby Professor of Ophthalmology in the Perelman School of Medicine at the University of Pennsylvania (Penn), and the Center for Retinal and Ocular Therapy (CAROT) at Penn, SPK-CHM demonstrated the ability to restore REP-1 protein production, intracellular trafficking and retinal structure.

The Phase 1/2 trial will be conducted at The Children's Hospital of Philadelphia (CHOP) and Penn, leveraging the same clinical study teams that conducted the Phase 1 and Phase 3 clinical trials of SPK-RPE65. The launch of this clinical trial is the latest development in an ongoing collaboration between Spark and Penn. Expanding upon an earlier collaboration around SPK-RPE65, in December of 2014 Spark and Penn, through Penn's technology commercialization organization, the Penn Center for Innovation (PCI), entered into an exclusive license agreement to certain Penn-owned intellectual property rights, including assets related to the choroideremia program.