Key TakeawaysBiogen has agreed to pay at least $1.15 billion for biotech firm Human Immunology Biosciences (HI-Bio) as it moves to increase its immunology portfolio.The deal includes the possibility of an additional $650 million in milestone payments. HI-Bio's lead asset treats rare kidney diseases. Biogen (BIIB) announced Wednesday it had purchased privately-held Human Immunology Biosciences (HI-Bio) for at least $1.15 billion to expand its reach into immunology medicines.  The company said that the $1.15 ...