Alexion did zero research and development on this drug.  They bought the entire company that did the reasearch and developed the drug,  company made up of professors doing work in university labs.  Alexion buys the drug and gets to sell it for 1 million a year per patient.  
What Alexion bought was a stream of profits protected by ridiculous agreements made with governments that protect the big pharma companies.  The original researchers work in university labs with grants and form a company to get corporate protection for profits.  After drug is approved they sell for huge profit to a Pharma company that is no more than a investment company.  This company now has a proven product that it can charge exorbitant amounts of money for because insurers and governments will pay.  Nothing was done in the interest of finding cures for rare diseases or patients.