Alexion Pharmaceuticals Inc. plucked another rare disease pearl with a deal to acquire Syntimmune Inc. and its humanized monoclonal antibody, SYNT-001, which is in phase I/II studies in the skin diseases pemphigus vulgaris (PV) and pemphigus foliaceus and the hematology indication warm autoimmune hemolytic anemia (WAIHA). SYNT-001, which inhibits interaction of the neonatal Fc receptor (FcRn) with immunoglobulin G (IgG) and IgG immune complexes, offers Boston-based Alexion development prospects in other rare IgG-mediated diseases, including neurology indications, with proof of mechanism showing rapid IgG reduction.