Novartis has bought itself rights to Spark Therapeutic’s gene therapy for a certain type of vision loss, in a deal worth up to $170 million.

The companies have signed a licensing agreement to develop and commercialise investigational voretigene neparvovec outside the US.

As per the deal, Spark will retain regulatory responsibility for obtaining European Medicines Agency approval for the therapy, where it is currently under review for patients with vision loss due to Leber congenital amaurosis or retinitis pigmentosa caused by confirmed biallelic RPE65 mutations.

The Swiss drug giant will pay Spark $105 million in cash upfront fee, as well as up to $65 million in cash milestone payments based on near-term European Regulatory Agency (EMA) regulatory approval/initial sales outside the US, and ex-US royalties.

Spark will continue to exclusively commercialise Luxturna (voretigene neparvovec-ryzl) in the US, where it is approved for patients with confirmed biallelic RPE65 mutation-associated retinal dystrophy.

The therapy works by delivering a normal copy of the RPE65 gene directly to retinal cells, which then produce the normal protein that converts light to an electrical signal in the retina to restore patient’s vision loss.