Spark Therapeutics said today it has acquired Genable Technologies for $15.15 million, in a deal that combines the buyer with its partner in a 2-year-old gene therapy collaboration to treat a leading cause of inherited retinal disease (IRD).

The deal adds Genable’s RhoNova™ to Spark’s portfolio of gene therapies for eye disorders. RhoNova is a treatment candidate for rhodopsin-linked autosomal dominant retinitis pigmentosa (RHO-adRP). RhoNova is designed to both suppress the expression of a faulty gene and deliver normal copies of the RHO gene to restore normal expression, through use of an adeno-associated virus (AAV) vector developed and manufactured at Spark.

Headquartered in Dublin, Ireland, Genable partnered with Spark in March 2014 to begin developing RhoNova, then called GT038. While the value of that collaboration was not disclosed, the companies said Spark will receive milestone payments and royalties on future sales of the gene therapy candidate, as well as near-term revenue from the manufacture and supply of product.

“Genable has provided convincing data in animals to support their innovative scientific approach for the treatment of autosomal dominant diseases, where it is critical to both suppress faulty genes and replace them with a functional copy in order to have a meaningful therapeutic effect,” Katherine A. High, M.D., Spark’s co-founder, president and CSO, said in a statement. “We look forward to using our validated gene therapy development platform and expertise to accelerate the clinical development of RhoNova, while examining other potential applications for the Genable suppression/augmentation approach outside of this initial indication.”

No approved pharmacologic treatment exists for RHO-adRP, which according to Spark and Genable affects an estimated 12,000 patients in the United States and the five major European markets (EU5). RhoNova has been granted Orphan Drug Designation in both the U.S. and Europe, as well as the European Medicines Agency’s Advanced Therapy Medicinal Product designation.

“This transaction advances our strategy of leveraging Spark’s best-in-class gene therapy platform through a combination of internal innovation, acquisition, and collaboration,” added Jeffrey D. Marrazzo, Spark co-founder and CEO. “Genable’s technology and promising RhoNova™ development program further strengthens our portfolio of treatments for IRDs.”

That portfolio is led by SPK-RPE65 (voretigene neparvovec), Spark’s Phase III gene therapy candidate for RPE65-mediated blindness. In October, Spark reported that SPK-RPE65 met its primary endpoint in a Phase III trial by showing improvement of functional vision in patients treated with the gene therapy candidate compared to a control group, as measured by the change in bilateral mobility testing between baseline and 1 year. SPK-RPE65 has received both breakthrough therapy and orphan product designations.

Spark agreed to acquire Genable for $6 million cash plus 265,000 shares of Spark common stock. While the company did not disclose additional financial information, Spark’s shares closed Friday at $34.53, bringing the value of the stock to $9.15 million.