Alexion Pharmaceuticals (NASDAQ: ALXN) is a US-headquartered biopharmaceutical company focused on developing and delivering therapies for patients with severe and life-threatening diseases.

Alexion was established in the US in 1992 and became a public company in 1996.

Alexion’s major product is Soliris (eculizumab), the world's first and only approved terminal complement inhibitor. Soliris is approved in nearly 50 countries as a treatment for patients with paroxysmal nocturnal hemoglobinuria (PNH), and in the United States, European Union, Japan and other countries as a treatment for patients with atypical hemolytic uremic syndrome (aHUS).

In January 2014, Alexion signed an exclusive strategic agreement with privately-held USA-based start-up Moderna Therapeutics for the discovery and development of messenger RNA Therapeutic to treat rare diseases. Alexion will lead the discovery, development and commercialization of the treatments produced through this broad, long-term strategic agreement, while Moderna will retain responsibility for the design and manufacture of the messenger RNA against selected targets.