Rallybio announces preliminary data from multiple dose cohort of RLYB212 trial

Rallybio announced preliminary data from the completed multiple dose cohort of the Phase 1 safety and pharmacokinetics, or PK, study for RLYB212, an anti-HPA-1a monoclonal antibody for the prevention of fetal and neonatal alloimmune thrombocytopenia. The Phase 1 multiple dose cohort for RLYB212 was initiated in the first quarter of 2023 to evaluate the safety and PK of subcutaneous, or SC, RLYB212 based on repeat dosing over 12 weeks. Eight HPA-1a negative subjects participated in the multiple dose cohort; six subjects received RLYB212 every 2 weeks and 2 received placebo every 2 weeks. The preliminary data demonstrated that multiple dose PK were consistent both within and between subjects. 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.