NAMPT and cancer: 16, 17 FK866, a specific inhibitor of NAMPT has been shown to possess anti-tumor activity against various human leukemic cells, including AML.18–20 In contrast, the normal hematopoietic progenitor cells remain unaffected.18, 20 This might be explained by the fact that the metabolic rate of cancer cells is abnormally high, and therefore, they require higher NAD+ levels. As a consequence of this, cancer cells have an increased sensitivity toward low levels of the cellular NAD+ content.