title: Preclinical pharmacokinetics, metabolism, and toxicity of azurin-p28 (NSC745104) a peptide inhibitor of p53 ubiquitination.
abstract: OBJECTIVE
  Characterize the preclinical pharmacokinetics, metabolic profile, multi-species toxicology, and antitumor efficacy of azurin-p28 (NSC 745104), an amphipathic, 28 amino acid fragment (aa 50-77) of the copper containing redox protein azurin that preferentially enters cancer cells and is currently under development for treatment of p53-positive solid tumors.
  
  
  METHODS
  An LC/MS/MS assay was developed, validated, and applied to liver microsomes, serum, and tumor cells to assess cellular uptake and metabolic stability. Pharmacokinetics was established after administration of a single intravenous dose of p28 in preclinical species undergoing chronic toxicity testing. Antitumor efficacy was assessed on human tumor xenografts. A human therapeutic dose was predicted based on efficacy and pharmacokinetic parameters.
  
  
  RESULTS
  p28 is stable, showed tumor penetration consistent with selective entry into tumor cells and significantly inhibited p53-positive tumor growth. Renal clearance, volume of distribution, and metabolic profile of p28 was relatively similar among species. p28 was non-immunogenic and non-toxic in mice and non-human primates (NHP). The no observed adverse effect level (NOAEL) was 120 mg/kg iv in female mice. A NOAEL was not established for male mice due to decreased heart and thymus weights that was reversible and did not result in limiting toxicity. In contrast, the NOAEL for p28 in NHP was defined as the highest dose (120 mg/kg/dose; 1,440 mg/m(2)/dose) studied. The maximum-tolerated dose (MTD) for subchronic administration of p28 to mice is >240 mg/kg/dose (720 mg/m(2)/dose), while the MTD for subchronic administration of p28 to Cynomolgous sp. is >120 mg/kg (1,440 mg/m(2)/dose). The efficacious (murine) dose of p28 was 10 mg/kg ip per day.
  
  
  CONCLUSIONS
  p28 does not exhibit preclinical immunogenicity or toxicity, has a similar metabolic profile among species, and is therapeutic in xenograft models.
authors.affiliation: Developmental Therapeutics Program, National Cancer Institute, Bethesda, MD 20852, USA.
authors.forename: Lee
authors.initials: L
authors.lastname: Jia
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Gorman
authors.forename: Lori U
authors.initials: LU
authors.lastname: Coward
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Noker
authors.forename: David
authors.initials: D
authors.lastname: McCormick
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Horn
authors.forename: J Brooks
authors.initials: JB
authors.lastname: Harder
authors.forename: Miguel
authors.initials: M
authors.lastname: Muzzio
authors.forename: Bellur
authors.initials: B
authors.lastname: Prabhakar
authors.forename: Balaji
authors.initials: B
authors.lastname: Ganesh
authors.forename: Tapas K
authors.initials: TK
authors.lastname: Das Gupta
authors.forename: Craig W
authors.initials: CW
authors.lastname: Beattie
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000009:adverse effects* / Q000378:metabolism / Q000493:pharmacokinetics* / Q000627:therapeutic use; D001400:Azurin / Q000009:adverse effects* / Q000378:metabolism / Q000493:pharmacokinetics* / Q000627:therapeutic use; D001711:Biotransformation; D045744:Cell Line, Tumor; D004353:Drug Evaluation, Preclinical; D005260:Female; D006801:Humans; D008252:Macaca fascicularis; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009369:Neoplasms / Q000188:drug therapy*; D019055:No-Observed-Adverse-Effect Level; D010446:Peptide Fragments / Q000009:adverse effects / Q000378:metabolism / Q000493:pharmacokinetics* / Q000627:therapeutic use; D013047:Specific Pathogen-Free Organisms; D047368:Tumor Burden / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D054875:Ubiquitination / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D010446:Peptide Fragments; D016159:Tumor Suppressor Protein p53; D001400:Azurin; C561466:azurin (50-77)