Rallybio has announced the initiation of a Phase II open-label trial of RLYB212, a novel therapeutic candidate, for the prevention of fetal and neonatal alloimmune thrombocytopenia (FNAIT) in pregnant women at higher risk. The trial, designed as a multi-center, single-arm study, aims to confirm the dosage and evaluate the pharmacokinetics and safety of RLYB212 when administered subcutaneously to pregnant women starting at gestational week 16 and continuing every four weeks until birth. The study is currently in the screening phase to identify the first participant.
The Phase II trial will enroll participants in three stages: beginning with a sentinel pregnant woman, followed by an initial cohort of three, and a second cohort of four, for a total of eight participants. Prior to the commencement of each new cohort, a review of outcomes for both participants and infants will be conducted. The study will recruit participants from multiple European countries, including the UK, Sweden, Belgium, Norway, and the Netherlands.
Trial Objectives and Design
The primary objectives of the Phase II trial are to assess the pharmacokinetics and safety of RLYB212 in pregnant women at risk for HPA-1a alloimmunization. Secondary objectives include monitoring pregnancy and neonatal outcomes and the emergence of HPA-1a alloimmunization. This comprehensive approach will provide critical data on the potential of RLYB212 to mitigate the risks associated with FNAIT.
FNAIT: A Rare but Serious Condition
FNAIT is a rare, potentially fatal condition that can lead to severe bleeding in fetuses and newborns. It arises from an immune reaction against a specific platelet antigen, typically human platelet antigen 1 (HPA-1a), when there is an incompatibility between the mother and fetus. This incompatibility can result in the mother's immune system attacking the fetal platelets, leading to thrombocytopenia and subsequent bleeding complications.
RLYB212: A Potential Solution
RLYB212 is being developed as a potential solution to prevent maternal alloimmunization and the resulting FNAIT. The initiation of this Phase II trial follows favorable data from a Phase I study of RLYB212, as outlined by Rallybio in November 2023. According to Rallybio CEO Stephen Uden, the commencement of screening in the RLYB212 Phase II trial represents a significant milestone in the company's mission to prevent maternal alloimmunization and FNAIT and its potentially catastrophic consequences. He also expressed gratitude to trial participants, investigators, site staff, and partners for their commitment to the shared mission and indicated that further updates on the trial’s progress would be provided upon dosing of the first participant.
