Gamma delta T-cell receptor ligands (γδ TCR ligands) (γδ TCR ligands)

Tumor cell surface ligands recognized by γδ T-cell receptors (γδ TCRs) represent a diverse array of molecules that trigger the non-MHC-restricted cytotoxic activity of γδ T-cells against malignant cells. The most well-characterized ligands are the butyrophilin family members, specifically BTN3A1 and BTN2A1, which are essential for the activation of the Vγ9Vδ2 T-cell subset—the predominant γδ T-cell population in human blood—in response to accumulated intracellular phosphoantigens (Rigau et al., Science 2020; Vavassori et al., Nat Immunol 2013). Other significant ligands include MHC class I-related molecules (MICA and MICB) and UL16-binding proteins (ULBPs), which act as stress-induced signals upregulated on the surface of various solid and hematological tumors (Groh et al., Science 1998). These ligands allow γδ T-cells to bypass traditional antigen presentation pathways, enabling rapid immune responses to cellular transformation. Therapeutic development focuses on targeting these ligands with monoclonal antibodies, such as ICT01 (targeting BTN3A), to enhance γδ T-cell-mediated tumor lysis (ImCheck Therapeutics, 2023). Additionally, the expression levels of these ligands, such as MICA/B, are being explored as biomarkers for patient selection in immunotherapeutic trials (Innate Pharma, 2022). The unique recognition mechanism of these ligands makes them promising candidates for "off-the-shelf" cellular therapies and bispecific engagers that do not require HLA matching.

Other names

Tumor cell surface ligands recognized by γδ T-cell receptorButyrophilinsMHC class I polypeptide-related sequence A/BMICAMICBUL16-binding proteinsULBPsButyrophilin 3A1BTN3A1Butyrophilin 2A1BTN2A1Endothelial protein C receptorEPCRAnnexin A2

Agonistic monoclonal antibodies that bind to and stabilize tumor cell surface ligands (such as BTN3A1 or MICA/B), thereby facilitating the activation and recruitment of γδ T-cells to the tumor microenvironment.