Preclinical data presented by Rallybio at the 66th American Society of Hematology Annual Meeting showcased potential advancements in preventing fetal and neonatal alloimmune thrombocytopenia (FNAIT) and treating iron overload disorders, according to a recently published press release.
FNAITFetal and neonatal alloimmune thrombocytopenia A rare condition in which a mother’s immune system attacks fetal platelets, leading to dangerously low platelet levels before and/or after birth. may be effectively addressed by RLYB212, according to new findings. In addition, RLYB332 demonstrated promise for managing diseases involving iron dysregulation. These developments could significantly improve outcomes for patients facing these rare and challenging conditions.
“With our Phase 2 trial underway evaluating RLYB212 in pregnant women at higher risk of maternal alloimmunizationAlloimmunization The process by which the mother becomes sensitized to fetal platelet antigens and begins producing alloantibodies. This is what causes FNAIT. and FNAIT, we are pleased that our collaborators at Versiti continue to add to the preclinical data showing RLYB212 has the potential to be a safe and effective preventative therapeutic using innovative nonclinical models,” said Stephen Uden, M.D., Chief Executive Officer of Rallybio. “Additionally, we are delighted to share, for the first time, preclinical data demonstrating the potential for RLYB332, our long-acting anti-matriptase-2 antibody, to be a best-in-class therapeutic for patients with diseases of iron overload.”
RLYB212, a human platelet antigenHuman platelet antigen Proteins found on the surface of platelets. Incompatibility between maternal and fetal human platelet antigens can trigger FNAIT.-1a–specific antibody, was tested in pregnant mice. At doses of 1.01 or 5.05 µg/kg, it successfully prevented maternal allo-immunization—a key factor in the development of FNAIT. Untreated mice produced pups with low platelet counts, whereas pups from RLYB212-treated mothers maintained normal levels. Furthermore, the antibody did not induce thrombocytopeniaThrombocytopenia A platelet count that is lower than normal. in offspring, underscoring its potential safety as a preventive treatment for high-risk pregnancies.
Read more about FNAIT treatment and care
For conditions involving iron overload, RLYB332, a long-acting anti-matriptase-2 antibody, demonstrated notable pharmacodynamic effects in humanized FcRnFc receptor A specialized transport protein. In FNAIT, it carries maternal antiplatelet IgG antibodies across the placenta into the fetus, which destroys the fetus's platelets. mice. Single intravenous doses led to reductions in serum iron, unsaturated iron binding capacity and transferrin saturation, outperforming comparator molecules. These sustained effects suggested that RLYB332 could become a leading therapy for managing disorders of iron dysregulation.
The importance of these developments lies in their potential impact on patients. FNAIT can cause severe complications for newborns, including bleeding disorders. Preventive measures such as RLYB212 could improve outcomes for both mothers and infants. Similarly, effective treatments for iron overload conditions, such as RLYB332, could alleviate symptoms and prevent complications associated with excessive iron, including organ damage.
Both therapies were generally well-tolerated in preclinical models, supporting their advancement into clinical trials. RLYB212 is currently undergoing a phase 2 trial in pregnant women at higher risk of maternal allo-immunization, marking an essential step in evaluating its effectiveness in humans.
