XmAb657 (CD19 x CD3)
CD19 x CD3 bispecific T-cell engager in Phase 1 development for autoimmune diseases
XmAb657 is an investigational CD19 x CD3 bispecific T-cell engager designed to redirect T cells to target and deplete CD19-expressing B cells. XmAb657 incorporates Xencor’s XmAb® 2+1 bispecific antibody format and Xtend™ Fc technology and is designed to provide potent B-cell depletion and an extended circulating half-life.
Xencor is conducting a first-in-human, Phase 1, open-label, dose-escalation study of subcutaneously administered XmAb657 in healthy participants and patients with idiopathic inflammatory myopathies, systemic sclerosis and Sjögren’s disease. The study is evaluating the safety, tolerability, pharmacokinetics, pharmacodynamics and immunogenicity of XmAb657.
In non-human primate studies, a single dose of XmAb657 reduced B cells by greater than 99.98% in peripheral blood, bone marrow and lymph nodes, with depletion sustained for at least 42 days. Xencor believes these findings support its evaluation for the treatment of autoimmune diseases in which B cells contribute to disease pathogenesis.