Biogen and Neurimmune announced that Biogen has exercised its option to further reduce the previously negotiated royalty rates payable on potential future sales of aducanumab, Biogen’s Phase 3 investigational treatment for early Alzheimer’s disease.   Biogen will make a one-time $50 million payment to Neurimmune in exchange for a 5% reduction in the original royalty rates on potential commercial sales of aducanumab, which follows the 15% reduction in royalty rates announced in October 20...