Rallybio Phase 2 trial of RLYB212 begins to tackle FNAIT in high-risk pregnancies

Rallybio Corporation (Nasdaq: RLYB), a clinical-stage biotechnology company known for advancing innovative therapies for rare diseases, has commenced its Phase 2 clinical trial for RLYB212. The trial focuses on preventing HPA-1a alloimmunization and fetal and neonatal alloimmune thrombocytopenia (FNAIT), a rare but life-threatening condition affecting pregnancies. The first screening phase to identify eligible pregnant women for participation is now underway.

FNAIT occurs when an immune mismatch between a pregnant mother and her fetus leads to the mother producing antibodies that attack the fetus’s platelets. This immune reaction, caused by an incompatibility in the human platelet antigen 1 (HPA-1) system, can lead to severe complications such as miscarriage, stillbirth, or lifelong disabilities. There are currently no approved treatments to prevent this condition, making Rallybio’s RLYB212 a potential game-changer.

Rallybio’s Chief Executive Officer, Stephen Uden, stated that the initiation of this trial marks a critical milestone in the company’s efforts to address this urgent medical need. He acknowledged the dedication of trial participants, investigators, and research partners, emphasising Rallybio’s commitment to improving maternal-fetal health outcomes.

The Phase 2 trial, registered under 2024-512651-20/NCT06435845, is designed to assess the pharmacokinetics and safety of RLYB212, which will be administered subcutaneously from the 16th week of gestation and repeated every four weeks until delivery. Secondary goals include evaluating pregnancy outcomes, neonatal health, and the prevention of HPA-1a alloimmunization.

Trial structure highlights safety and precision

The trial will enrol eight pregnant participants in three stages. The first stage involves monitoring a single (sentinel) participant to ensure safety, followed by two cohorts, with three and four participants respectively. Each stage will include a thorough review of maternal and infant data before progressing to the next phase. Recruitment sites are located across Belgium, the Netherlands, Norway, Sweden, and the United Kingdom, reflecting the trial’s international scope.

Dr. Vasilis Sitras, Head of Fetal Medicine at Oslo University Hospital, underscored the profound impact of FNAIT on families and highlighted the urgent need for effective prevention. He expressed optimism about the potential of RLYB212 to transform outcomes for expectant mothers and their babies, offering hope to those affected by this devastating condition.

Rallybio’s broader mission

Rallybio’s pipeline reflects its commitment to tackling unmet medical needs in rare diseases. In addition to RLYB212, the company is developing RLYB116, an inhibitor of complement component 5 (C5), targeting diseases associated with complement dysregulation. Rallybio’s work spans maternal-fetal health, hematology, and metabolic disorders, reinforcing its position as a leader in clinical innovation.

Based in New Haven, Connecticut, Rallybio continues to advance its mission of delivering life-transforming therapies. With the development of RLYB212, the company is addressing a critical gap in prenatal and maternal healthcare, potentially offering a solution to a problem with no current treatment options.