title: Fenretinide therapy in prostate cancer: effects on tissue and serum retinoid concentration.
abstract: OBJECTIVE
  To examine the feasibility of using fenretinide (4-HPR) for the prevention and treatment of prostate cancer.
  
  
  METHODS
  We measured the impact of 4-HPR therapy on retinoid concentrations in vivo, in a mouse model of prostate cancer and clinically, in patients with prostate cancer who were given oral 4-HPR (200 mg/d) or placebo for 4 weeks before undergoing a radical prostatectomy.
  
  
  RESULTS
  Prostate tumors in mice treated with 4-HPR contained high levels of 4-HPR and of all-trans-retinoic acid (RA) and reduced levels of retinol (ROH). Patients given 4-HPR were found to have significantly higher concentrations of 4-HPR in the cancerous prostate as compared with the serum levels (463 nmol/L v 326 nmol/L; P =.049), but they were only 1/10 the levels found in mice and were far below the concentrations reported in human breast tissue. Serum and tissue ROH levels were reduced to less than half the concentrations found in untreated controls. RA concentrations in human serum and in cancerous prostates were not significantly affected by 4-HPR treatment, in contrast with the findings in mice.
  
  
  CONCLUSIONS
  The standard oral dose of 4-HPR proposed for breast cancer (200 mg/d) achieved only modest drug levels in the prostate and is unlikely to be effective for prostate cancer prevention or treatment. Higher doses need to be explored.
authors.affiliation: Department of Biochemistry, Matsunaga-Conte Prostate Cancer Research Center, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: C
authors.initials: C
authors.lastname: Thaller
authors.forename: M
authors.initials: M
authors.lastname: Shalev
authors.forename: A
authors.initials: A
authors.lastname: Frolov
authors.forename: G
authors.initials: G
authors.lastname: Eichele
authors.forename: T C
authors.initials: TC
authors.lastname: Thompson
authors.forename: R H
authors.initials: RH
authors.lastname: Williams
authors.forename: O
authors.initials: O
authors.lastname: Dillioglugil
authors.forename: D
authors.initials: D
authors.lastname: Kadmon
mesh_terms: D000368:Aged; D000818:Animals; D000970:Antineoplastic Agents / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*; D004311:Double-Blind Method; D017313:Fenretinide / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008875:Middle Aged; D010919:Placebos; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000601:surgery; D014212:Tretinoin / Q000097:blood / Q000378:metabolism*; D014801:Vitamin A / Q000097:blood / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D010919:Placebos; D014801:Vitamin A; D017313:Fenretinide; D014212:Tretinoin