The new licensing deal between Akebia and Otsuka expands upon a pact made last December for U.S. commercial rights.
Biogen adjusted profit rose in the first quarter on a small increase in total revenue. Sales of the biotech company's multiple sclerosis drugs remain flat.
When Biogen reports first-quarter earnings Tuesday, investors will be looking to see if Spinraza sales match or exceed $16 million consensus.
If approved, Brineura will be the first and only treatment for CLN2 disease, a form of Batten disease.