Alexion Pharmaceuticals, Inc.  has entered into a definitive agreement to acquire Achillion Pharmaceuticals, Inc., a clinical-stage biopharmaceutical company, for approximately $930 million.

Achillion is focused on the development of oral small molecule Factor D inhibitors to treat people with complement alternative pathway-mediated rare diseases, such as paroxysmal nocturnal hemoglobinuria (PNH) and C3 glomerulopathy (C3G). Achillion currently has two candidates in development, including danicopan (ACH-4471) in Phase II and ACH-5228 in Phase I.

“Alexion has demonstrated the transformative impact that inhibiting C5 can have on multiple rare and devastating diseases. However, we believe this is just the beginning of what’s possible with complement inhibition,” said Ludwig Hantson, Ph.D., chief executive officer of Alexion. “Targeting a different part of the complement system – the alternative pathway – by inhibiting Factor D production addresses uncontrolled complement activation further upstream in the complement cascade, and importantly, leaves the rest of the complement system intact, which is critical in maintaining the body’s ability to fight infection. We believe this approach has the opportunity to help patients with diseases not currently addressed through C5 inhibition. We look forward to applying our nearly three decades of complement and development expertise to unlock the potential of oral Factor D inhibitors and bring these benefits to patients.”

“We have established great momentum – discovering and advancing several small molecules into clinical development that have the potential to treat immune-related diseases associated with the alternative pathway of the complement system,” said Joe Truitt, president and chief executive officer at Achillion. “Having already demonstrated proof-of-concept and proof-of-mechanism with our lead candidate, danicopan (ACH-4471), in PNH and C3G, respectively, we believe there is significant opportunity for Factor D inhibition in the treatment of other diseases as well. Alexion is an established leader in developing medicines for complement-mediated diseases, and we look forward to working together to accelerate our objective of bringing novel therapies to patients as quickly as possible and ensuring that the broad promise of this approach is fully realized. We thank our employees, investigators and partners for their incredible work and commitment.”

The acquisition, subject to the approval of Achillion shareholders and customary closing conditions, is expected to close in 1H20.