Momenta Pharmaceuticals, Inc. announced new preclinical data for M281, its potentially best-in-class anti-FcRn antibody, was published in the American Journal of Obstetrics & Gynecology. The data show that M281 inhibits maternal to fetal IgG transfer in the human ex vivo term placental perfusion model, while showing minimal transfer itself to fetal circulation. About M281: M281 is a fully human anti-neonatal Fc receptor (FcRn), aglycosylated immunoglobulin G (IgG1) monoclonal antibody, engineered to reduce circulating pathogenic IgG antibodies by blocking endogenous IgG recycling via FcRn. Momenta previously reported positive data showing safety, tolerability and proof of mechanism for M281 in a Phase 1 single ascending dose (SAD) and multiple ascending dose (MAD) study of normal human volunteers. Over the 98-day MAD study, M281 exhibited no serious adverse events, was well tolerated, and decreased circulating IgG levels up to 89% with a mean reduction of 84%. M281 is currently being evaluated in Phase 2 studies in generalized myasthenia gravis2 and in early onset antenatal HDFN3 with plans for an additional Phase 2 autoimmune study later this year.