US-based Pharmaceutical firm Alexion has signed a definitive agreement to acquire Achillion Pharmaceuticals, a clinical-stage biopharmaceutical company, for about $930m.

Achillion is engaged in the development of oral small molecule Factor D inhibitors to treat people with complement alternative pathway-mediated rare diseases, including paroxysmal nocturnal hemoglobinuria (PNH) and C3 glomerulopathy (C3G).

Achillion president and chief executive officer Joe Truitt said: “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.

“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.”

The deal would add a portfolio of oral small molecule Factor D inhibitors to Alexion’s pipeline

Under the terms of the agreement, Alexion would pay an initial consideration of approximately $930m, or $6.30 per share of Achillion common stock, in cash. The deal also includes the cash currently on Achillion’s balance sheet.

Alexion said that the transaction includes the potential for additional consideration in the form of non-tradeable contingent value rights (CVRs), paid to Achillion shareholders subject to the achievement of certain clinical and regulatory milestones within specified periods.

The CVRs include $1.00 per share for the following the US FDA approval of danicopan and $1.00 per share for initiation of Phase 3 ACH-5228.

The transaction is expected to close in the first half of 2020, subject to the approval of Achillion shareholders, the fulfilment of customary closing conditions and approval from relevant regulatory agencies, including clearance under the Hart-Scott Rodino Antitrust Improvements Act.

Alexion said that Achillion is currently developing two clinical-stage medicines, danicopan (ACH-4471) in Phase 2 and ACH-5228 in Phase 1, and the acquisition would add a clinical-stage portfolio of oral small molecule Factor D inhibitors to its pipeline.

The transaction would provide an opportunity to enhance treatment for PNH patients experiencing extravascular hemolysis (EVH), potential first-in-class C3 glomerulopathy (C3G) therapy.

In addition, the deal would also enable the development of a promising platform for Factor D inhibition in additional alternative pathway complement-mediated rare diseases.

Alexion chief executive officer Ludwig Hantson said: “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.

“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.”