Biogen has completed its acquisition of Nightstar Therapeutics, a gene therapy company focused on adeno-associated virus (AAV) treatments for inherited retinal disorders, in a transaction valued at approximately $800 million.   With the acquisition, Biogen has added two mid- to late-stage clinical assets, as well as preclinical programs, in ophthalmology. NST’s lead asset is NSR-REP1 for the treatment of choroideremia (CHM), a rare, degenerative, X-linked inherited retinal disorder, which lead...