Rallybio Announces Proof-of-Concept Achieved for RLYB212, a Novel Monoclonal anti-HPA-1a Antibody to Prevent Fetal and Neonatal Alloimmune Thrombocytopenia
-- RLYB212 Showed Rapid Elimination of Transfused, HPA-1a Positive Platelets in HPA-1a Negative Subjects --
-- Clinical Findings and Safety Profile Consistent with Previously Reported Data; Continue to Support the Potential for RLYB212 as a Prophylactic Treatment for FNAIT --
-- Company Expects to Present Results at a
Additional findings from the study show:
- The reduction in mean platelet elimination half-life was greater than 90% in both RLYB212 dose groups compared to placebo and was dose related.
- The broad range of pharmacokinetic and pharmacodynamic data allows substantive modeling to inform dose selection for a future registrational study.
- RLYB212 was observed to be well-tolerated with no serious adverse events reported.
The Company expects to report data from the Phase 1b clinical study of RLYB212 at a scientific conference in 2023.
“Our FNAIT development program has consistently demonstrated the effectiveness of anti-HPA-1a antibodies to rapidly eliminate HPA-1a positive platelets from the circulation of HPA-1a negative subjects,” commented Róisín Armstrong, Ph.D., Rallybio’s RLYB212 Program Lead. “We’ve also established in published nonclinical studies the association between rapid platelet elimination and prevention of HPA-1a alloimmunization, which can lead to negative and potentially life-threatening outcomes in FNAIT. Collectively, these data reinforce our belief on the potential for an anti-HPA-1a antibody to be a viable approach for preventing FNAIT and we look forward to continued advancement of the RLYB212 development program.”
Given the favorable development profile of RLYB212 to date, the data generated to date for RLYB212, and the expected manufacturing and supply efficiencies for RLYB212, the Company also announced today that RLYB211, a plasma-derived polyclonal anti-HPA-1a antibody, will not be advanced further in clinical development.
About the RLYB212 Phase 1b Study
Rallybio’s Phase 1b study is a single-blind, placebo-controlled proof-of-concept study designed to establish the ability of subcutaneous RLYB212 to rapidly accelerate the elimination of HPA-1a positive platelets transfused to HPA-1a negative healthy male participants. In this single-center, EU-based study, the elimination of transfused platelets serves as a surrogate for assessing the ability of an anti-HPA-1a antibody to drive rapid elimination of HPA-1a positive fetal platelets from an expectant mother’s circulation, thereby potentially preventing HPA-1a maternal alloimmunization and the occurrence of FNAIT in fetuses and newborns. The platelet challenge in this model represents an equivalent fetal maternal hemorrhage of 30 mL, a rare and catastrophic scenario during pregnancy.
The Phase 1b study has been conducted at the Clinical Research department of the
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 specific platelet antigen called human platelet antigen 1, or HPA-1.
There are two predominant forms of HPA-1, known as HPA-1a and HPA-1b, which are expressed on the surface of platelets. Individuals who are homozygous for HPA-1b, meaning that they have two copies of the HPA-1b allele and no copies of the HPA-1a allele, are also known as HPA-1a negative. Upon exposure to the HPA-1a antigen, these individuals can develop antibodies to that antigen in a process known as alloimmunization. In expectant mothers, alloimmunization can occur upon mixing of fetal blood with maternal blood. When alloimmunization occurs in an expectant mother, the anti-HPA-1a 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.
This press release contains forward-looking statements that are based on our management’s beliefs and assumptions and on currently available information. In some cases, forward-looking statements can be identified by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplate,” “believe,” “estimate,” “predict,” “potential” or “continue” or the negative of these terms or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements in this press release include, but are not limited to, statements concerning substance, design and timing of our planned or ongoing studies for RLYB212, the timing of the availability of data from such studies, our expectations regarding reporting of data from such studies, our expectations regarding the usefulness such data, the success of modeling to inform dosing for a future registrational study, our ability to advance RLYB212 into future clinical studies, and the likelihood that
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