Alexion Pharmaceuticals has agreed to acquire Syntimmune, for up to $1.2 billion, the companies said today, in a deal designed to broaden the buyer’s rare disease pipeline.

Founded in 2013, Syntimmune is a Boston-based developer of antibody therapeutics targeting the neonatal Fc receptor (FcRn). The company’s lead candidate SYNT001, is an immunoglobulin G4 (IgG4) monoclonal antibody optimized to inhibit FcRn binding to IgG at both neutral and acidic pH.

According to Syntimmune, studies have shown that SYNT001 rapidly facilitates clearance of IgG and IgG circulating immune complexes (CICs), with the potential to block innate immune responses induced by IgG and CIC, as well as inhibit T-cell and B-cell activation in response to CIC. The company has also cited studies suggesting that SYNT001 acts on IgG without destroying immune cells or impacting other types of immunoglobulin—and that SYNT001 has the potential to exert a rapid therapeutic effect in a wide range of IgG-mediated autoimmune diseases.

SYNT001 is under study in Phase Ib/IIa trials in patients with warm autoimmune hemolytic anemia (WAIHA) (NCT03075878), as well as in patients with pemphigus vulgaris (PV) or pemphigus foliaceus (PF) (NCT03075904). SYNT001 is also in Phase Ia studies for an additional as-yet-unspecified dermatology indication, and two as-yet-unspecified indications in neurology, according to Syntimmune’s website.

“SYNT001 has successfully demonstrated proof of mechanism—the ability to rapidly lower IgG levels—in early clinical studies and has the potential to treat a number of rare IgG-mediated diseases,” Alexion CEO Ludwig Hantson, Ph.D., said in a statement. “The acquisition of Syntimmune represents a critical step in rebuilding Alexion’s pipeline and further diversifying the company’s clinical-stage rare disease portfolio.

Alexion has agreed to pay $400 million upfront for Syntimmune, and up to $800 million in payments tied to achieving milestones.

Alexion said it intends to finance the acquisition through cash on hand. The buyer reported $727.5 million in cash and cash equivalents as of June 30.

The deal is expected to close in the fourth quarter, subject to approval from regulatory agencies and other customary closing conditions.

‘Strong Strategic Fit’

Dr. Hantson added that Syntimmune offered a “strong strategic fit” with Alexion’s existing rare disease franchises, noting that SYNT001 was the first, and currently the only, anti-FcRn therapy in clinical development for WAIHA.

Alexion’s main marketed drug is Soliris® (eculizumab), a complement inhibitor with indications in paroxysmal nocturnal hemoglobinuria (PNH), atypical hemolytic uremic syndrome (aHUS), and generalized myasthenia gravis in adults who are anti-acetylcholine receptor antibody positive. Soliris generated $1.698 billion in net product sales during the first half of this year, up 6% from $1.597 billion a year earlier.

Other Alexion marketed drugs include Strensiq® (asfotase alfa) for hypophosphatasia, and Kanuma® (sebelipase alfa) for lysosomal acid lipase deficiency. In August, the FDA accepted for review Alexion’s Biologics License Application (BLA) for its long-acting C5 complement inhibitor candidate ALXN1210 for PNH, which is also in a Phase III trial (NCT03131219) for aHUS.

Also in advanced development within Alexion’s clinical pipeline is Wilson disease candidate WTX101 (bis-choline tetrathiomolybdate), a first-in-class copper-protein-binding agent now under study in a Phase III trial (NCT03403205).

“Alexion’s demonstrated rare disease expertise and development and commercial capabilities provide an ideal foundation for continued advancement of SYNT001 and, we believe, will ensure its broad potential is realized,” adds Seth Harrison, M.D., chairman of Syntimmune.

Dr. Harrison is also managing partner of Apple Tree Partners, which committed $48 million of the $50 million in Series B financing raised by Syntimmune in June 2017. Proceeds from the financing were to be used toward advancing the company’s clinical development program, including the Phase Ib/IIa trials of SYNT001 in PV, PF, and WAIHA.

Alexion’s acquisition of Syntimmune comes a year after the company eliminated approximately 20% of its workforce and announced it would move its headquarters from New Haven, CT, to Boston, in a restructuring overseen by Dr. Hantson. He took the company’s helm in March 2017 following the December 2016 resignations of CEO David Hallal and his CFO, Vikas Sinha.

A month later, Alexion acknowledged that unnamed “senior management” members pressured some customers to place “pull-in,” or advance, orders for shipments of Soliris in order to meet financial targets.

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