Combined activity of the cancer metabolism inhibitor MPC-8640 and 5-fluorouracil in xenograft models.

e13581 Background: Nicotinamide (Nam) phosphoribosyltransferase (Nampt) catalyzes the rate-limiting step in NAD biosynthesis from Nam. Nampt inhibition causes NAD depletion, inhibition of ATP synthesis and cell death. MPI-0487316 is a selective Nampt inhibitor with potent tumoricidal activity against cancer cell lines of diverse origin. MPC-8640, an orally bioavailable prodrug of MPI-0487316, induces regressions in xenograft models. Combining Nampt inhibitors with 5-fluorouracil (5-FU) results in synergistic tumoricidal activity in cells. We have explored the combination of MPC-8640 with 5-FU in a colon carcinoma xenograft model. Methods: In vitro studies were done in HCT-116 human colon carcinoma cells. Cell viability was measured by determining ATP levels. Xenograft studies were done with cells implanted subcutaneously into athymic mice (nu/nu). MPC-8640 was dosed orally at 12 to 48 mg/kg daily on Days 1-7 and 15-21. 5-FU was dosed intraperitoneally, weekly at 100 mg/kg. Results: MPI-0487316 showed syne...