CD38 (tumor cells) x CD3 (T cells)

Class

Bispecific T-cell engaging antibody

Pathway

Bridges CD38-expressing multiple myeloma cells to CD3-positive T cells, driving T-cell-mediated cytotoxicity

CD38 is a cell-surface glycoprotein expressed at high density on plasma cells, the antibody-producing cells that become malignant in multiple myeloma. CD3 is a signaling component of the T-cell receptor complex found on essentially all T lymphocytes, the immune cells responsible for direct cell killing. A bispecific T-cell engaging antibody is a single engineered protein with two distinct binding arms: one arm binds CD38 on the tumor cell, the other binds CD3 on a T cell. By binding both simultaneously, the antibody physically bridges the two cell types, forcing an artificial synapse between them. This close contact activates the T cell independent of its normal antigen-recognition process, triggering it to release cytotoxic granules that kill the attached tumor cell. The biological rationale is to harness the killing capacity of the patient's own T-cell repertoire and direct it specifically toward CD38-high malignant plasma cells, rather than relying on antibody-dependent mechanisms alone. This approach broadly matters in multiple myeloma and other plasma-cell disorders, where CD38 is consistently and abundantly expressed, and in settings where prior therapies have depleted or exhausted natural anti-tumor immune responses, since engagement bypasses the need for pre-existing tumor-reactive T cells.