Swiss drugmaker Novartis on Sunday said it agreed to acquire US biotech firm Avidity Biosciences for about $12 billion in cash, as the company looks to bolster its portfolio of treatments for rare muscle disorders. Avidity stockholders will receive $72 per share in cash, representing a premium of 46% to the company’s closing on Friday. Novartis has been proactively striking deals this year to address the impending patent cliff for some of its blockbuster drugs, including Entresto for heart