SPK-RPE65 targets a group of blinding conditions known as inherited retinal dystrophies (IRDs).
IRDs are caused by autosomal recessive mutations in the RPE65 gene, for which currently there is no pharmacologic treatment available.
The FDA breakthrough therapy status was supported by two earlier clinical trials, which suggest that SPK-RPE65 allows patients to perform activities of daily living with greater independence than prior to treatment, and has long-lasting effects in restoring functional vision.
Spark Therapeutics co-founder and chief executive officer Jeffrey Marrazzo said: "FDA’s breakthrough therapy designation for SPK-RPE65 underscores the serious unmet medical needs faced by patients with genetic blinding conditions.
"We look forward to working closely with FDA to facilitate the review of SPK-RPE65 as we work to bring this potentially transformative treatment to patients."
The trials showed that following a single injection of SPK-RPE65 in one eye, children no longer depended on visual aids to conduct classroom activities and were able to walk and play more like normally sighted children.
Currently, SPK-RPE65 is being evaluated in a fully-enrolled pivotal Phase III clinical trial and its resulst are expected to be reported in the second half of 2015.