Natural killer group 2 member D ligands and Fc-gamma receptor IIIa (CD16a) substrates (NKG2DL/CD16a-substrates)

Tumor cell surface stress ligands and antibody-coated tumor cells represent a composite target profile primarily recognized by Natural Killer (NK) cells and cytotoxic T cells to initiate anti-tumor effector functions. Stress ligands, such as MHC class I polypeptide-related sequence A/B (MICA/B) and UL16-binding proteins (ULBPs), are upregulated on the surface of cells undergoing malignant transformation or DNA damage, serving as 'eat-me' signals for the NKG2D receptor. Simultaneously, tumor cells coated with IgG antibodies (opsonized) are targeted through the engagement of Fc-gamma receptor IIIa (CD16a), triggering Antibody-Dependent Cellular Cytotoxicity (ADCC). In the context of oncology, these targets are exploited by monoclonal antibodies and next-generation innate cell engagers to bridge the gap between the innate immune system and the tumor. Therapeutic strategies aim to overcome immune evasion mechanisms, such as the proteolytic shedding of stress ligands which can act as decoys. By enhancing the density of these signals or preventing their loss, clinicians can promote more robust immune-mediated clearance of cancer cells. This target profile is central to the efficacy of many established biologics and is a major focus for developing bispecific and trispecific NK cell-engaging therapies.

Other names

NKG2D ligandsMICA/BUL16-binding proteinsAntibody-dependent cellular cytotoxicity (ADCC) targetsOpsonized tumor cellsStress-induced ligands

Drugs targeting these components typically act by facilitating Antibody-Dependent Cellular Cytotoxicity (ADCC) or by enhancing the recognition of stress ligands by Natural Killer (NK) cells and T cells via the NKG2D receptor. Therapeutic antibodies coat tumor cells to engage CD16a (FcγRIIIa) on effector cells, while newer bispecific innate cell engagers (ICEs) bridge tumor-associated antigens or stress ligands directly to NK cell activating receptors.