Rallybio Corporation announced preliminary data from the completed multiple dose cohort of the Phase 1 safety and pharmacokinetics (PK) study for RLYB212, an anti-HPA-1a monoclonal antibody for the prevention of fetal and neonatal alloimmune thrombocytopenia. The preliminary data and the Company's clinical pharmacology modeling predictions support a once monthly dosing regimen for the planned Phase 2 study. Consistent with previously reported data, RLYB212 was observed to be generally well-tolerated with no reports of injection site reactions or serious adverse events.

Rallybio also announced that the RLYB212 toxicology package to support the planned Phase 2 and Phase 3 studies, including the maternal fetal toxicology program, is complete. Rallybio expects to submit both the RLYB212 clinical pharmacology model and the Phase 2 dosing approach, including supportive clinical and nonclinical data, to a peer reviewed journal in 2024. The study included two cohorts: a previously completed single dose cohort and a multiple dose cohort.

The Phase 1 study was conducted at the Clinical Research department of the Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, in Frankfurt/Main, Germany, in collaboration with the Institute of Transfusion Medicine and Immunohaematology, German Red Cross (Deutsches Rotes Kreuz) Blood Transfusion Service Baden-Wurttemberg-Hessen gGmbH in Frankfurt/Main, Germany.