title: On-target effect of FK866, a nicotinamide phosphoribosyl transferase inhibitor, by apoptosis-mediated death in chronic lymphocytic leukemia cells.
abstract: OBJECTIVE
  Chronic lymphocytic leukemia (CLL) remains incurable despite advances in therapy. In this study, we characterize the effect of nicotinamide phosphoribosyltransferase (NAMPT) inhibition by FK866 in primary CLL cells from patients with various clinical prognostic markers.
  
  
  METHODS
  CLL cells were treated with FK866 to assess viability by Annexin V/PI staining. Functional analysis of FK866 included time- and concentration-dependent evaluation of cellular NAD, ATP, mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and apoptotic signaling. Chemosensitization potential by FK866 to fludarabine was also assessed. Prognostic markers were correlated with drug response.
  
  
  RESULTS
  FK866 induced CLL cell death by depleting cellular NAD content by day 1, followed by a drop in ATP on day 2. We observed loss of MMP, ROS increase, and induction of apoptotic signaling at day 3. On-target activity of FK866 was confirmed by NAD-mediated rescue of NAD and ATP loss, apoptotic signaling, and viability. The response to FK866 was independent of most prognostic markers. Higher doses were required with short lymphocyte doubling time and positive CD38 status, whereas CLL cells resistant to fludarabine in vitro and from patients with del17p13.1 were equally sensitive to FK866. FK866 did not upregulate the p53-target p21, nor did the p53 activator Nutlin improve FK866-mediated cell death. Furthermore, fludarabine and FK866 were synergistic at clinically relevant concentrations.
  
  
  CONCLUSIONS
  NAMPT inhibition by FK866 may be a potential treatment for CLL, including patients with del17p13.1 or other high-risk features. FK866 may complement standard agents to enhance their efficacy and/or allow dose reduction for improved tolerability.
authors.affiliation: CancerCare Manitoba, Winnipeg, Manitoba, Canada. Manitoba Institute of Cell Biology, Winnipeg, Manitoba, Canada. Departments of.
authors.forename: Iris
authors.initials: I
authors.lastname: Gehrke
authors.affiliation: Manitoba Institute of Cell Biology, Winnipeg, Manitoba, Canada. Departments of Biochemistry and Medical Genetics and.
authors.forename: Eric D J
authors.initials: ED
authors.lastname: Bouchard
authors.affiliation: Manitoba Institute of Cell Biology, Winnipeg, Manitoba, Canada. Departments of Biochemistry and Medical Genetics and.
authors.forename: Sara
authors.initials: S
authors.lastname: Beiggi
authors.affiliation: CancerCare Manitoba, Winnipeg, Manitoba, Canada. Manitoba Institute of Cell Biology, Winnipeg, Manitoba, Canada. Departments of.
authors.forename: Armando G
authors.initials: AG
authors.lastname: Poeppl
authors.affiliation: CancerCare Manitoba, Winnipeg, Manitoba, Canada. Manitoba Institute of Cell Biology, Winnipeg, Manitoba, Canada. Departments of Internal Medicine, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: James B
authors.initials: JB
authors.lastname: Johnston
authors.affiliation: Manitoba Institute of Cell Biology, Winnipeg, Manitoba, Canada. Departments of Biochemistry and Medical Genetics and.
authors.forename: Spencer B
authors.initials: SB
authors.lastname: Gibson
authors.affiliation: CancerCare Manitoba, Winnipeg, Manitoba, Canada. Manitoba Institute of Cell Biology, Winnipeg, Manitoba, Canada. Departments of Biochemistry and Medical Genetics and Internal Medicine, University of Manitoba, Winnipeg, Manitoba, Canada. versha.banerji@cancercare.mb.ca.
authors.forename: Versha
authors.initials: V
authors.lastname: Banerji
mesh_terms: D000178:Acrylamides / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002478:Cells, Cultured; D016207:Cytokines / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D015151:Immunoblotting; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism* / Q000473:pathology; D054409:Nicotinamide Phosphoribosyltransferase / Q000037:antagonists & inhibitors; D010880:Piperidines / Q000494:pharmacology*
chemical_list: D000178:Acrylamides; D000970:Antineoplastic Agents; D016207:Cytokines; D004791:Enzyme Inhibitors; C480543:N-(4-(1-benzoylpiperidin-4-yl)butyl)-3-(pyridin-3-yl)acrylamide; D010880:Piperidines; D054409:Nicotinamide Phosphoribosyltransferase; C085455:nicotinamide phosphoribosyltransferase, human