NAMPT and neoplasm: It should be mentioned that in one study utilizing NA in combination with the NAMPT inhibitor GNE-617, the antitumor activity of the latter was found to be prevented by the concomitant NA administration in NAPRT-deficient tumor xenograft models, which was ascribed to an increased NAM and NAD+ production in the liver with the consequent rise in tumor NAM and NAD+ levels.