Rallybio Announces Collaboration to Advance Solutions for Pregnant Women at Risk of Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT)

NEW HAVEN, Conn. — Rallybio Corporation (Nasdaq: RLYB), a clinical-stage biotechnology company committed to identifying and accelerating the development of life-transforming therapies for patients with severe and rare diseases, today announced a collaboration with Johnson & Johnson to support the development of complementary therapeutic approaches aimed at reducing the risk of fetal and neonatal alloimmune thrombocytopenia (FNAIT). In addition, Rallybio received an equity investment of $6.6 million from Johnson & Johnson Innovation – JJDC, Inc.

Rallybio is developing RLYB212, a novel human monoclonal anti-HPA-1a antibody designed to prevent pregnant women from alloimmunizing, thereby eliminating the risk of FNAIT and its potentially devastating consequences in their fetuses and newborns. Rallybio is on track to initiate a Phase 2 dose confirmation study for RLYB212 in pregnant women at higher risk of alloimmunization and FNAIT in the second half of 2024.

Under this collaboration, Johnson & Johnson will provide funding for Rallybio to raise awareness of Johnson & Johnson’s FNAIT clinical program in connection with Rallybio’s ongoing FNAIT natural history study. Rallybio is also eligible to receive additional payments under the collaboration.

RLYB212 is the only investigational therapy currently reported to be in clinical development to address the needs of pregnant individuals at risk of FNAIT who have not alloimmunized2. Johnson & Johnson is conducting a Phase 3 study of nipocalimab, an investigational monoclonal antibody targeting FcRn, in pregnant individuals who are already alloimmunized. As these individuals have the alloantibodies that can cause FNAIT, preventative treatment with RLYB212 would not be appropriate.

“We are thrilled to be working with Johnson & Johnson on our mission to eliminate FNAIT,” said Stephen Uden, M.D., Chief Executive Officer of Rallybio. “Our complementary approaches, if successful, would ensure that pregnant women at risk of developing FNAIT have a potential treatment option – regardless of their alloimmunization status. Together, we can more effectively and expeditiously drive awareness of FNAIT, emphasize the importance of screening pregnant women for their risk of developing FNAIT, and advance our complementary therapeutic approaches.”

Rallybio is currently conducting a natural history study designed to provide a contemporary dataset for HPA-1a alloimmunization frequency in a racially and ethnically diverse population that is intended to support a future RLYB212 registration study. Pregnant women who are already alloimmunized are not eligible for inclusion in Rallybio’s natural history study, nor for potential preventative treatment with Rallybio’s investigational therapeutic, RLYB212.



Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT) is a potentially life-threatening rare disease that can cause uncontrolled bleeding in fetuses and newborns. FNAIT can arise during pregnancy due to an immune incompatibility between an expectant mother and her fetus in a platelet antigen. When alloimmunization occurs in an expectant mother, the antibodies that develop in the mother can cross the placenta and destroy platelets in the fetus. The destruction of platelets in the fetus can result in severely low platelet counts, or thrombocytopenia, and potentially lead to devastating consequences including miscarriage, stillbirth, death of the newborn, or severe lifelong neurological disability in those babies who survive. There is currently no approved therapy for the prevention or prenatal treatment of FNAIT.


About Rallybio

Rallybio (Nasdaq: RLYB) is a clinical-stage biotechnology company with a mission to develop and commercialize life-transforming therapies for patients with severe and rare diseases. Rallybio has built a broad pipeline of promising product candidates aimed at addressing diseases with unmet medical need in areas of maternal fetal health, complement dysregulation, hematology, and metabolic disorders. The Company has two clinical stage programs: RLYB212, an anti-HPA-1a antibody for the prevention of fetal and neonatal alloimmune thrombocytopenia (FNAIT) and RLYB116, an inhibitor of complement component 5 (C5), with the potential to treat several diseases of complement dysregulation, as well as additional programs in preclinical development. Rallybio is headquartered in New Haven, Connecticut.


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