ATI-2173 is a novel phosphoramidate pro-drug of clevudine. The molecule was designed to selectively deliver the 5’ monophosphate to the liver, potentially eliminating the off-target effects of clevudine, while retaining the unique anti-HBV activity of the active 5’ triphosphate.

Unlike other nucleoside analogues against HBV, the active 5’ triphosphate of ATI-2173 is not a chain terminator. It binds to the active site of the HBV polymerase, altering the structure of the enzyme, preventing its own incorporation into DNA, while inhibiting all stages of HBV DNA synthesis (priming, priming polymerization and post-priming DNA synthesis).