Natural killer group 2 member D receptor (NKG2D) (NKG2D)

The engineered NKG2D receptor domain is the recognition component of a novel class of Chimeric Antigen Receptor (CAR) T-cell therapies designed to target a broad spectrum of cancers. Unlike traditional CAR-Ts that use antibody-derived fragments to target a single antigen, this construct utilizes the extracellular domain of the human NKG2D receptor (KLRK1), a natural activating receptor found on NK cells (UniProt P26718) [1]. This domain allows the CAR-T cell to recognize eight different stress-induced ligands—MICA, MICB, and ULBP1-6—which are frequently upregulated in both hematological and solid tumors due to DNA damage or oncogenic transformation [2]. Upon ligand binding, the CAR-T cell undergoes activation via fused intracellular signaling domains like CD3-zeta and 4-1BB, leading to direct tumor cell lysis and proinflammatory cytokine production [3]. Clinical candidates such as CYAD-01 have demonstrated the feasibility of this approach in treating refractory acute myeloid leukemia and colorectal cancer [4]. However, therapeutic challenges include potential 'on-target, off-tumor' toxicity if ligands are expressed on healthy tissues, and the presence of soluble ligands that can act as decoys to inhibit CAR-T activity [5]. The versatility of the NKG2D domain makes it an attractive candidate for 'universal' CAR-T applications across multiple tumor types. Research is ongoing to optimize the hinge and signaling domains to enhance the persistence and efficacy of these engineered cells in the immunosuppressive tumor microenvironment [6].

Other names

KLRK1CD314Killer cell lectin-like receptor subfamily K member 1NKG2-D-activating NK receptorNKG2D-CAR

The engineered NKG2D receptor domain on CAR-T cells acts as a chimeric antigen receptor that binds to stress-induced ligands (MICA, MICB, and ULBP1-6) on tumor cells, triggering T-cell activation and cytotoxic activity.