Days after the FDA approved Biogen Idec Inc.’s Alprolix (coagulation factor IX [recombinant], Fc fusion protein) as the first recombinant, DNA-derived hemophilia B therapy with prolonged circulation, Baxter International Inc. moved to strengthen its own hemophilia franchise by snapping up the assets of Chatham Therapeutics LLC in a $70 million deal plus potential development, regulatory and commercial milestone payments.