A Phase 2 clinical trial is underway to evaluate the safety and pharmacokinetics of RLYB212, a monoclonal antibody treatment for preventing fetal and neonatal alloimmune thrombocytopenia (FNAIT) in pregnant women at higher risk for alloimmunization, according to study information posted recently on ClinicalTrials.gov.
RLYB212 has the potential to significantly reduce risks to both mothers and their babies during pregnancy and delivery. FNAIT is a rare but serious condition in which a mother’s immune system creates antibodies that attack the platelets of her unborn baby, leading to complications such as low platelet counts, bleeding, or even stillbirth.
This study focuses on women who lack the HPA-1a antigen and carry an HPA-1a-positive fetus, which places them at risk of developing these harmful antibodies. Pregnant participants receive subcutaneous injections of RLYB212 throughout their pregnancy, with maternal exposure measured at regular intervals from gestational week 16 to postpartum week four.
This trial, conducted across multiple centers, involves a rigorous screening process to identify eligible participants. Women must be HPA-1b/b, HLA-DRB3*01:01 positive, and free of anti-HPA-1a alloantibodies. They must also carry a single fetus, as multiple pregnancies or a history of FNAIT disqualify participation. Once enrolled, participants undergo antenatal treatment and a follow-up phase lasting up to 10 weeks postpartum.
Read more about FNAIT therapies
Researchers will monitor primary outcomes, including treatment-related adverse events and maternal exposure levels of RLYB212. Secondary outcomes measure neonatal exposure, platelet counts, and overall health at birth and four to six weeks postpartum. The study also evaluates pregnancy outcomes, such as live births and preterm deliveries, offering a comprehensive assessment of the therapy’s safety and efficacy.
This trial marks a significant step in addressing FNAIT, as current treatments are limited and often involve reactive measures such as platelet transfusions after complications arise. If successful, RLYB212 could offer a proactive, safe solution for preventing alloimmunization, reducing anxiety and medical risks for affected families.
The results of this study will guide future research and potentially transform care for at-risk pregnancies, providing hope for healthier outcomes for mothers and their newborns.
