Fluorine F 18 Ara-G

**Semantic type:** Indicator, Reagent, or Diagnostic Aid|Pharmacologic Substance

**Definition:** A radioconjugate composed of the guanosine analog arabinosyl guanine (Ara-G), a high-affinity substrate for both cytoplasmic deoxycytidine kinase (DCK) and mitochondrial deoxyguanosine kinase (dGK), labeled with fluorine F 18, that can potentially be used as a tracer for imaging of activated T-lymphocytes during positron emission tomography (PET). Upon administration, fluorine F 18 ara-G is taken up by and accumulates in activated T-lymphocytes with high levels of DCK and dGK. After phosphorylation by DCK and dGK, the 18F moiety can be visualized by PET imaging. Fluorine F 18 ara-G can potentially be used as an imaging agent to detect anti-tumor immune responses and to predict the therapeutic efficacy of immunotherapies. DCK and dGK, both nucleoside salvage pathway enzymes, are overexpressed in activated T-cells.

**Synonyms:** - (18F)F-Arag - 18F-F-Ara-G - 2'-Deoxy-2'-[18F]Fluoro-9-beta-D-arabinofuranosylguanine - 2-Amino-9-((2R,3S,4R,5R)-3-fluoranyl-4-hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-1H-purin-6-one - F-ARAG F-18 - F-ARAG F-18 - VisAcT - [18F]-AraG - [18F]F-AraG - [18F]F-ara-G