E5B9 peptide (E5B9)

The E5B9 peptide is a 10-amino acid sequence (KPLPEVTDEY) derived from the human nuclear autoantigen La (also known as Sjögren's syndrome-associated antigen B or SS-B) [2, 3, 8]. It is a cryptic epitope, meaning it is not accessible in the native, folded La protein and thus does not trigger an autoimmune response in healthy individuals [2, 12]. This peptide serves as the fundamental recognition component of the UniCAR (Universal Chimeric Antigen Receptor) platform, a modular immunotherapy system designed to enhance the safety and controllability of CAR T-cell therapy [1, 2, 10]. In the UniCAR system, effector cells (such as T-cells or NK cells) are engineered to express a universal receptor that specifically recognizes the E5B9 peptide rather than a tumor antigen [3, 5, 9]. Therapeutic redirection is achieved using bifunctional "Target Modules" (TMs) that bridge the UniCAR effector cells to tumor cells by binding to a tumor-associated antigen on one end and the E5B9 peptide on the other [1, 4, 8]. This approach allows clinicians to regulate the intensity and duration of the immune response by adjusting the dosage of the TM, providing a "safety switch" to mitigate potential toxicities like cytokine release syndrome or on-target/off-tumor effects [1, 2, 12].

Other names

E5B9 epitopeLa/SS-B peptide epitopeLa-derived peptideKPLPEVTDEY peptide

Acts as a bridge/adaptor to redirect UniCAR-expressing immune cells to tumor cells by binding to the UniCAR's extracellular domain.