Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT) is a disorder caused by maternal alloantibodies directed against paternally inherited fetal platelet antigens, most commonly human platelet antigen-1a (HPA-1a). These antibodies cross the placenta, leading to fetal thrombocytopenia and an increased risk of intracranial hemorrhage and other bleeding complications.
Rallybio has announced on April 8th to discontinue the clinical development of RLYB212, a monoclonal antibody candidate for the prevention of FNAIT. The single-arm Phase 2 dose confirmation trial was designed to assess the PK and safety of RLYB212 in pregnant women at higher risk for HPA-1a alloimmunization and FNAIT. The trial’s sentinel participant failed to meet predicted target concentrations necessary for efficacy, leading the company to conclude that dose adjustment is not viable.