A Phase 2 clinical trial for an experimental treatment for fetal and neonatal alloimmune thrombocytopenia (FNAIT) was recently approved by the European Medicines Agency (EMA), according to a recently published press release.
The clinical trial aims to assess the absorption, metabolism and excretion of RLYB21. Additionally, the study will evaluate the outcomes after RLYB12 administration and if it prevented alloimmunization against fetal Human Platelet Antigen 1 (HPA-1).
This experimental monoclonal antibody targets the HPA-1a antibody to prevent FNAIT in at-risk pregnancies. The drug is administered subcutaneously every 4 weeks beginning at week 16 of gestation.
Learn more about FNAIT therapies
Researchers are recruiting patients in Belgium; they expect to recruit eight pregnant patients at risk of FNAIT.
Stephen Uden, M.D., Chief Executive Officer of Rallybio, stated, “We are activating clinical sites and expect to initiate screening this quarter, which will mark another important step toward achieving our mission to prevent FNAIT and its potentially devastating consequences.”
Understanding HPA-1 Blocking
“In HPA-1a-negative expectant mothers bearing a HPA-1a-positive fetus, alloimmunization can occur upon mixing of fetal blood with maternal blood,” the authors wrote. “When alloimmunization occurs in an expectant mother, the anti-HPA-1a antibodies that develop in the mother can cross the placenta and destroy platelets in the fetus,”
Monoclonal antibodies such as RLYB12 are human-made antibodies that target a specific molecule for therapeutic process. In the context of FNAIT, monoclonal antibodies targeting the HPA-1 represent one of the most promising therapeutic and preventive strategies.
Monoclonal antibodies can block the binding of maternal antibodies to fetal platelets, thus preventing an immune response that results in platelet destruction and life-threatening thrombocytopenia. Furthermore, studies in mice have shown that administering monoclonal antibodies against HPA-1 to mothers before exposure to HPA-1-positive platelets could prevent alloimmunization.
