Tumor cell surface antigens and stress ligands

Tumor cell surface antigens and stress ligands represent a broad category of molecules expressed on the exterior of malignant cells that serve as critical recognition signals for the host immune system. Tumor-associated antigens (TAAs) are often proteins overexpressed in cancer cells compared to normal tissues, while stress ligands, such as MHC class I polypeptide-related sequence A and B (MICA/B) and UL16-binding proteins (ULBPs), are specifically upregulated in response to genomic instability, oxidative stress, or viral infection (Source: Nature Reviews Immunology, 2019). These ligands are primarily recognized by the NKG2D activating receptor found on Natural Killer (NK) cells and CD8+ T cells, triggering a cytotoxic response against the stressed cell (Source: Frontiers in Immunology, 2020). In clinical oncology, these molecules are exploited as targets for monoclonal antibodies, bispecific openers, and CAR-T/NK cell therapies to enhance anti-tumor immunity (Source: PubMed, PMID: 31515458). However, tumors frequently evade this detection by proteolytically shedding these ligands from the cell surface, creating soluble decoys that inhibit immune cell function and contribute to therapeutic resistance (Source: Journal of Hematology & Oncology, 2021). Because this term describes a heterogeneous group of molecules rather than a single protein, it is classified as a target category rather than a specific canonical target.

Other names

Tumor-associated antigens (TAAs)Tumor-specific antigens (TSAs)Stress-induced ligandsNKG2D ligandsCancer cell surface markers

Therapeutic agents targeting these molecules typically induce tumor cell death through antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), or by directing chimeric antigen receptor (CAR) T-cells and Natural Killer (NK) cells to lyse the target cell upon recognition of the surface antigen or stress ligand.