Alexion closed the final agreement to acquire Syntimmune, a clinical-stage biotechnology company developing antibody therapeutics targeting the neonatal Fc receptor (FcRn), for an upfront payment of $400 million and additional milestone-dependent payments of up to $800 million.

Syntimmune’s lead candidate, SYNT001, is a humanized monoclonal antibody that inhibits the interaction of FcRn with Immunoglobulin G (IgG) and IgG immune complexes currently in Phase 1b/2a studies in patients with warm autoimmune hemolytic anemia and in patients with pemphigus vulgaris or pemphigus foliaceus. It has demonstrated proof of mechanism showing rapid IgG reduction.