FcRH5 (FcRL5) x CD3

Class

Bispecific antibody (T-cell engager)

Pathway

T-cell redirection against FcRH5-expressing myeloma cells

FcRH5 (also called FcRL5) is a surface protein found predominantly on plasma cells, including the malignant plasma cells that characterize multiple myeloma. CD3 is a signaling component of the T-cell receptor complex present on essentially all T lymphocytes. A bispecific antibody that binds both simultaneously acts as a physical bridge, positioning a patient's own T cells directly against tumor cells regardless of the T cell's original antigen specificity. This is a form of T-cell redirection: rather than relying on the immune system to naturally recognize the cancer, the drug forces an immune synapse between cytotoxic T cells and myeloma cells, triggering T-cell activation and release of cytotoxic granules that kill the tumor cell. The rationale for targeting FcRH5 specifically is its relatively restricted, high expression on plasma cells, which provides a tumor-associated marker distinct from other myeloma targets. This approach broadly matters in hematologic malignancies, particularly for myeloma that has progressed despite standard therapies, because it introduces a mechanism of tumor killing that does not depend on the specific mutations or antigen-presentation status of the cancer cells, offering an option when other treatment classes have been exhausted.