BCMA, GPRC5D, FcRH5

Class

mRNA-encoded multiplexed T-cell engager therapy (LNP-delivered, in vivo translated bispecific antibodies)

Pathway

T-cell redirection/engagement

Notes

original target text: BCMA, GPRC5D, FcRH5 -- three separate T-cell engagers encoded in one mRNA-LNP product

This mechanism uses T-cell engagers, a class of bispecific antibodies that bind simultaneously to CD3 on a patient's own T cells and to a tumor-associated antigen on malignant cells, forcing formation of a synapse that activates the T cell to kill the tumor cell without needing the T cell's native antigen receptor to recognize the target. Here, three such engagers—directed against BCMA, GPRC5D, and FcRH5, three different proteins found on malignant plasma cells in multiple myeloma—are combined in a single product. Rather than being manufactured as recombinant proteins, the antibodies are encoded as messenger RNA packaged in lipid nanoparticles (LNPs); after injection, the patient's own cells transiently translate the mRNA into the functional bispecific proteins. The rationale for targeting three antigens at once is that myeloma cells are heterogeneous, and some cells may lose or downregulate any single antigen under selective pressure, allowing relapse. Engaging multiple independent antigens in parallel is intended to reduce the chance that antigen-negative tumor clones escape immune killing. This approach broadly matters in hematologic malignancies, particularly multiple myeloma, where antigen escape has been observed as a limitation of single-target immunotherapies.