Adapter molecule for modular CAR-T cell targeting

**Adapter molecules for engineered CAR-T cells** are modular agents, often protein- or peptide-based, that enable the targeting of chimeric antigen receptor (CAR)-modified T cells to a desired tumor antigen by serving as a bridge between the CAR (engineered to bind the adapter) and the tumor antigen (bound by the adapter via antibody fragment, ligand, or other binding motif)[6][7][3][9]. This system separates antigen recognition from the signaling machinery of CAR-T cells, allowing clinicians to redirect a single CAR-T cell product against multiple antigens by changing only the adapter molecule, enhancing flexibility and potentially improving safety via better control (e.g., by turning activity off when the adapter is withheld)[6][7]. Examples include bispecific proteins, peptide–Fab conjugates, or engineered miniproteins designed for high affinity and specificity in both arms (CAR and antigen). Such adapters are often not found in nature and are specifically designed for use in modular CAR-T platforms, such as "GA1CAR," "UniCAR," or other split/plug-and-play CAR systems[6][7][3][9]. **Note:** This entry refers to a class of engineered molecules and not a single canonical human protein; the common thread is their design for modular CAR-T cell targeting, typically with two binding interfaces—one for the engineered CAR and one for the selected tumor antigen[6][7][9].

Other names

Adapter proteinAdapter moleculeModular adapterSplit-CAR adapterBispecific adapter

Binds engineered CAR-T cell surface receptor (designed to recognize the adapter rather than the tumor antigen directly) Binds to tumor antigen (via a separate binding moiety, e.g., an antibody fragment) Bridges tumor cell and immune cell, enabling controlled and modular T cell activation against a selected tumor antigen Allows for rapid retargeting by changing the adapter molecule, and can act as an on/off switch by withholding the adapter