** Shares of drugmaker Biogen BIIB.O rise 5.8% to $213.75 premarket

** Biogen says it has either paused or discontinued funding for most of the research programs included in its $5.6 billion acquisition of Apellis Pharmaceuticals' assets

** The U.S. drugmaker has also cut a small number of roles within the research organization as it shifts resources toward Empaveli and Syfovre, the approved therapies acquired through the deal

** The company did not offer details on the number of roles or the specific programs impacted by the decision

** Including session's move, BIIB shares up 20% YTD