The acquisition brings Alexion the bleeding reversal agent Andexxa, which execs called a synergistic addition to its portfolio – but analysts are struggling to see the match with Alexion’s chronic rare disease therapies.

Besting Alexion’s Soliris in a head-to-head Phase III trial portends a place in the market for Apellis’ competitor in paroxysmal nocturnal hemoglobinuria. But challenges dog both companies.

Bristol-Myers Squibb’s newly acquired company Celgene is one of two drug sponsors that this month made it onto the European Medicines Agency’s priority medicines scheme. The other is Achillion Pharmaceuticals, which is developing a treatment for paroxysmal nocturnal hemoglobinuria.