B cells mature into plasmablasts and plasma cells that are prolific antibody producers and the predominant source of pathogenic autoantibodies, a hallmark of RA. Autoantibodies contribute to the pathogenesis of RA in several ways, including formation of immune complexes, activation of complement and downstream cell lysis. Clinical trials of cizutamig (BCMAxCD3 T-cell engager) demonstrated safety and efficacy in RRMM. Cizutamig offers a promising mechanism of action for refractory seropositive RA. This study aims to assess the safety, tolerability, PK, pharmacodynamics, immunogenicity, and preliminary clinical activity of cizutamig administered in patients with refractory seropositive RA. Patients will be invited to participate in the study, to receive cizutamig and monitored after dosing with cizutamig through Week 52.
