Biogen Inc. (Nasdaq: BIIB) agreed to acquire Human Immunology Biosciences Inc. for as much as $1.8 billion in a deal aimed at bolstering the biotechnology giant’s pipeline of immune disease treatments. 

Biogen Chief Executive Officer Chris Viehbacher has been searching for smaller deals as sales of its mainstay multiple sclerosis medications decline and it waits for revenues from its new Alzheimer’s drug to start rising. Human Immunology’s drug could work in a range of immune-mediated diseases. It’s being developed for a kidney condition called primary membranous nephropathy and for complications after kidney transplants, Bloomberg News reported.