XmAb657 (CD19 x CD3)
Rationally designed CD19 x CD3 bispecific T-cell engager for patients with autoimmune diseases
Xencor has leveraged its XmAb® protein engineering platforms to create XmAb657, a potent, potentially long-acting CD19 x CD3 bispecific antibody, utilizing the XmAb 2+1 bispecific antibody format and Xtend™ Fc technology. In non-human primate studies, a single dose of XmAb657 deeply reduced B cells by over 99.98% in the peripheral compartment, bone marrow and lymph nodes at both high and low doses tested, which was sustained for at least 28 days. Half-life was estimated to be 15 days, which indicates a potential for durable B-cell depletion in clinical studies. XmAb657 was well tolerated preclinically, with no clinical signs of cytokine release syndrome.
Xencor plans to initiate a first-in-human study during the second half of 2025. (Press Release, September 9, 2024)