CD19 / CD20 (dual-antigen) with CD3 T-cell engagement

Class

CD19/CD20 bispecific T-cell engager (biologic)

Pathway

Redirects CD3+ T cells to deplete CD19+/CD20+ B cells implicated in B-cell-driven autoimmune disease

CD19 and CD20 are proteins found on the surface of B lymphocytes, immune cells that produce antibodies and that, in autoimmune disease, can generate antibodies against a person's own tissues. CD19 appears from early B-cell development through late plasmablast stages, while CD20 is present on a somewhat different but overlapping window of B-cell maturation. A bispecific T-cell engager is an engineered antibody-like molecule built with two binding arms: one arm attaches to a B-cell surface marker, and the other attaches to CD3, a signaling component on T cells. By linking a B cell and a T cell physically, the molecule prompts the T cell to attack and destroy the B cell, independent of what that B cell happens to be reacting against. Engaging two B-cell antigens, CD19 and CD20, rather than one, is intended to capture a broader population of B cells, including ones that have reduced expression of a single marker, and to lessen the chance that antigen-negative cells survive and repopulate. This class of molecule is being investigated in autoimmune conditions where pathogenic B cells persist despite standard immune-suppressing therapies, with the goal of achieving more thorough and durable depletion than approaches directed at a single B-cell antigen.