Rallybio, a U.S.-based biotechnology company, has commenced a Phase II clinical trial in Europe to evaluate RLYB212 as a potential treatment for fetal and neonatal alloimmune thrombocytopenia (FNAIT). The first subject has been dosed in this trial, marking a significant step in the development of a therapy for this rare and potentially life-threatening condition.
The single-arm, dose confirmation trial is designed to assess the pharmacokinetics (PK) and safety of RLYB212 in pregnant women who are at a higher risk for human platelet antigen (HPA) 1a alloimmunization and FNAIT. The study is enrolling subjects at sites across Europe in three stages, beginning with a sentinel pregnant woman, followed by two cohorts with a total enrollment target of eight subjects.
Trial Design and Objectives
The Phase II trial is an open-label study where pregnant women will receive RLYB212 subcutaneously by gestational week 16, continuing every four weeks until birth. The primary objectives include assessing the PK and safety of RLYB212. Secondary objectives involve evaluating pregnancy and neonatal/infant findings, as well as monitoring for the emergence of HPA-1a alloimmunization.
Data review for subjects and infants will be conducted before the start of each cohort. Initial data from the second trimester are expected to be available by the second quarter of this year, with further outcomes of PK and safety at the delivery time anticipated in the third quarter.
RLYB212 Mechanism of Action
RLYB212 is a monoclonal antibody engineered to prevent maternal alloimmunization. It functions by rapidly eliminating HPA-1a positive fetal platelets from the mother's circulation. This mechanism aims to prevent the mother's immune system from becoming sensitized to the fetal platelets, thereby eliminating the risk of FNAIT.
FNAIT: A Rare but Serious Condition
FNAIT is a rare condition that can cause severe bleeding in fetuses and newborns due to an immune reaction against a specific platelet antigen. It occurs when there is an immune incompatibility between an expectant mother and her fetus concerning the human platelet antigen 1. If the mother develops antibodies against the fetal platelets, it can lead to thrombocytopenia and subsequent bleeding complications in the fetus or newborn.
Management Perspective
Rallybio CEO Stephen Uden stated, "Dosing the sentinel participant in our RLYB212 Phase II trial marks a significant milestone for our RLYB212 program and for Rallybio. We plan to provide an update in the second quarter, as we continue to advance our mission to deliver a safe and effective therapeutic to prevent maternal alloimmunization and the potentially catastrophic consequences of FNAIT."
The trial is being conducted in multiple centers across Europe, including sites in the UK, Sweden, Belgium, Norway, and the Netherlands.
