C-X-C motif chemokine receptor 3 (CXCR3) (CXCR3)

The C-X-C motif chemokine receptor 3 (CXCR3) is a G protein-coupled receptor primarily expressed on activated T lymphocytes, natural killer cells, and effector/memory T cells, where it binds chemokines CXCL9, CXCL10, and CXCL11 to drive chemotaxis, leukocyte trafficking, and Th1 immune responses. It exists in isoforms including CXCR3-A (promoting proliferation, survival, invasion on hematopoietic cells), CXCR3-B (inhibitory on endothelial cells via cAMP), and CXCR3-alt, with opposing functions that influence angiogenesis and cell migration. CXCR3 plays key roles in inflammation by directing immune cells to inflamed tissues and in cancer by modulating tumor progression, metastasis (e.g., melanoma, colon, prostate), and immune suppression in tumors like pancreatic ductal adenocarcinoma. In autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, and lupus, as well as transplant rejection and infections (including HIV co-receptor activity), CXCR3 ligands are overexpressed, making it a promising therapeutic target. Antagonists like AMG 487 and ACT-777991 block ligand binding to inhibit pathological signaling, showing preclinical efficacy in inflammation, autoimmunity, and cancer models, with some advancing to clinical trials for tolerability and pharmacodynamics. Biased agonists highlight pathway-specific effects, such as β-arrestin bias enhancing T cell migration. Challenges include balancing anti-inflammatory benefits against impairing anti-tumor immunity.

Other names

G protein-coupled receptor 9 (GPR9)CD183MigRCXC-R3interferon-inducible protein 10 receptorIP-10 receptorCKR-L2

Antagonism (blocks binding of ligands CXCL9, CXCL10, CXCL11), Biased agonism (G protein or β-arrestin pathways)