Benzylguanine-conjugated monoclonal antibody adaptor (BG-mAb) (BG-mAb)

Benzylguanine-conjugated (BG-conjugated) monoclonal antibody adaptors are synthetic intermediary molecules used in modular chimeric antigen receptor (CAR) T-cell systems, such as the SNAP-CAR platform (Rodgers et al., 2016, PNAS). These adaptors consist of a monoclonal antibody specific for a tumor-associated antigen (TAA) that has been chemically conjugated with O6-benzylguanine (BG) moieties, which serve as substrates for the SNAP-tag enzyme (Keppler et al., 2003, Nature Biotechnology). In this therapeutic architecture, the adaptor acts as a programmable bridge: the antibody domain binds to the TAA on the tumor cell surface, while the BG group provides a site for covalent attachment to T cells engineered to express a SNAP-tag-based CAR. Upon interaction, the SNAP-tag on the CAR-T cell reacts irreversibly with the BG moiety on the adaptor, forming a stable covalent bond that triggers T-cell activation and subsequent tumor cell lysis (Zah et al., 2016, Molecular Therapy). This modular design allows for the targeting of multiple antigens using a single CAR-T cell product and provides a mechanism to control therapeutic activity by adjusting the adaptor's dosage or administration schedule.

Other names

SNAP-tag adaptorBG-conjugated antibodyO6-benzylguanine-modified monoclonal antibodyModular CAR-T adaptor

The adaptor binds to a tumor-associated antigen via its variable regions, while its conjugated benzylguanine (BG) moiety forms a covalent bond with a SNAP-tag-based chimeric antigen receptor (CAR) on the surface of T cells, triggering cytotoxic activity (Rodgers et al., 2016, PNAS).