Rallybio Corporation (Nasdaq: RLYB) has announced the approval of its clinical trial applications (CTAs) for a Phase 2 clinical trial of RLYB212 in pregnant women at higher risk for HPA-1a alloimmunization and fetal and neonatal alloimmune thrombocytopenia (FNAIT). Approvals were granted by the European Medicines Agency (EMA) and the United Kingdom’s Medicines and Healthcare products Regulatory Agency (MHRA). The company expects to initiate screening of participants in the fourth quarter of 2024.
Phase 2 Trial Details
The single-arm Phase 2 dose confirmation trial (2024-512651-20/NCT06435845) will be conducted in Belgium, the Netherlands, Norway, Sweden, and the UK. It is designed to assess the pharmacokinetics (PK) and safety of RLYB212, a monoclonal anti-HPA-1a antibody, in eight pregnant women at higher risk for HPA-1a alloimmunization and FNAIT. Secondary objectives include assessments of pregnancy and neonatal/infant outcomes, and the occurrence of emergent HPA-1a alloimmunization. Subcutaneous administration of RLYB212 will be initiated by Gestational Week 16 and will continue every 4 weeks through parturition.
RLYB212: A Novel Approach to FNAIT Prevention
RLYB212 represents a novel prophylactic approach for preventing alloimmunization in pregnant women at higher risk for FNAIT. FNAIT is a potentially life-threatening rare disease that can cause uncontrolled bleeding in fetuses and newborns. It arises during pregnancy due to an immune incompatibility between an expectant mother and her fetus involving the human platelet antigen 1 (HPA-1).
There are two predominant forms of HPA-1, known as HPA-1a and HPA-1b. Individuals who are homozygous for HPA-1b (HPA-1a negative) can develop antibodies to the HPA-1a antigen upon exposure, a process known as alloimmunization. In HPA-1a-negative expectant mothers bearing a HPA-1a-positive fetus, alloimmunization can occur upon mixing of fetal blood with maternal blood. The resulting anti-HPA-1a antibodies can cross the placenta and destroy platelets in the fetus, leading to thrombocytopenia and potentially severe consequences, including miscarriage, stillbirth, death of the newborn, or severe lifelong neurological disability. Currently, there is no approved therapy for the prevention or prenatal treatment of FNAIT.
Leadership Perspective
“Securing these CTA approvals from European health authorities to advance RLYB212 into a Phase 2 trial is a significant achievement,” said Stephen Uden, M.D., Chief Executive Officer of Rallybio. “These approvals are a testament to the dedication and innovation of our team and our partners as we advance this first ever program to prevent maternal alloimmunization and FNAIT.”
Steven Ryder, M.D., Chief Medical Officer at Rallybio, added, “These approvals recognize Rallybio’s commitment to safely and effectively progress a novel prophylactic approach for preventing alloimmunization in pregnant women at higher FNAIT risk. We are proud to be leaders in bringing much needed innovation to this area of women’s health, which has gone unaddressed for far too long.”
