Biogen has signed a pact with AGTC to develop its gene-based therapies for multiple ophthalmic diseases in a deal valued at more than $1 billion.

The US biotech giant is shelling out $124 million upfront to seal the collaboration, which includes a $30 million equity investment in AGTC and certain prepaid research and development expenditures, for access to key eye disease programmes.

The alliance will focus on the development of a portfolio of AGTC’s therapeutic offerings, including a clinical stage candidate for X-linked Retinoschisis and a preclinical candidate for X-Linked Retinitis Pigmentosa, both orphan diseases of the retina that can lead to blindness in children and adults.

The agreement also includes options for early stage discovery programs in two ophthalmic diseases and one non-ophthalmic condition, the firms said.

As per the deal, AGTC is eligible to receive upfront and milestone payments exceeding $1 billion, which includes up to $472.5 million for the two lead programs, as well as royalties in the high single digit to mid-teen percentages of annual net sales.

Biogen will also make payments up to $592.5 million across the discovery programs, along with royalties in the mid single digits to low teen percentages of annual net sales.

The deal is expected to close in the third quarter of this year.