title: Identification and validation of phospho-SRC, a novel and potential pharmacodynamic biomarker for dasatinib (SPRYCEL), a multi-targeted kinase inhibitor.
abstract: OBJECTIVE
  Dasatinib (BMS-354825) is a potent, oral multi-targeted kinase inhibitor. It is an effective therapy for patients with imatinib-resistant or -intolerant Ph+ leukemias,. It has demonstrated promising preclinical anti-tumor activity, and is under clinical evaluation in solid tumors. To support the clinical development of dasatinib, we identified a pharmacodynamic biomarker to assess in vivo SRC kinase inhibition, with subsequent evaluation in cancer patients.
  
  
  METHODS
  The biomarker, phosphorylated SRC (phospho-SRC), was first identified in human prostate PC-3 tumor cells and peripheral blood mononuclear cells (PBMCs) in vitro. It was further assessed in nude mice bearing PC-3 xenografts. Phospho-SRC[pY418] in tumors and PBMC were measured by western blot analysis, and were quantified by ELISA assays. Dasatinib plasma concentrations were determined using LC/MS/MS.
  
  
  RESULTS
  In PC-3 cells, dasatinib showed dose-dependent anti-proliferative effect, which correlated with the inhibition of phospho-SRC[pY418] and of SRC kinase activity. With a single oral dose of 50 or 15 mg/kg, tumoral phospho-SRC[pY418] was maximally inhibited at 3 h, partially reversed between 7 and 17 h, and completely recovered after 24 h post dose. At 5 mg/kg, tumoral phospho-SRC[pY418] inhibition was less pronounced and recovered more rapidly to baseline level within 24h. Dasatinib (1 mg/kg) resulted in little inhibition. In PBMCs, a similar time course and extent of phospho-SRC[pY418] inhibition was observed. Inhibition of phospho-SRC[pY418] in vivo appeared to correlate with the preclinical in vivo efficacy and PK profiles of dasatinib in mice.
  
  
  CONCLUSIONS
  Phospho-SRC[pY418] may potentially be used as a biomarker to enable assessment of target inhibition in clinical studies exploring dasatinib antitumor activity.
authors.affiliation: Pharmaceutical Research Institute, Clinical Discovery, Bristol-Myers Squibb Company, Pennington, NJ 08534, USA.
authors.forename: Feng Roger
authors.initials: FR
authors.lastname: Luo
authors.forename: Yu Chen
authors.initials: YC
authors.lastname: Barrett
authors.forename: Zheng
authors.initials: Z
authors.lastname: Yang
authors.forename: Amy
authors.initials: A
authors.lastname: Camuso
authors.forename: Kelly
authors.initials: K
authors.lastname: McGlinchey
authors.forename: Mei-Li
authors.initials: ML
authors.lastname: Wen
authors.forename: Richard
authors.initials: R
authors.lastname: Smykla
authors.forename: Krista
authors.initials: K
authors.lastname: Fager
authors.forename: Robert
authors.initials: R
authors.lastname: Wild
authors.forename: Holly
authors.initials: H
authors.lastname: Palme
authors.forename: Susan
authors.initials: S
authors.lastname: Galbraith
authors.forename: Anne
authors.initials: A
authors.lastname: Blackwood-Chirchir
authors.forename: Francis Y
authors.initials: FY
authors.lastname: Lee
mesh_terms: D000230:Adenocarcinoma / Q000737:chemistry / Q000188:drug therapy / Q000473:pathology*; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D015415:Biomarkers; D002455:Cell Division / Q000187:drug effects; D000069439:Dasatinib; D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000737:chemistry / Q000187:drug effects; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009363:Neoplasm Proteins / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000097:blood; D010750:Phosphoproteins / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D011471:Prostatic Neoplasms / Q000737:chemistry / Q000188:drug therapy / Q000473:pathology*; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D011743:Pyrimidines / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D013047:Specific Pathogen-Free Organisms; D013379:Substrate Specificity; D013844:Thiazoles / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D023041:Xenograft Model Antitumor Assays; D019061:src-Family Kinases / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000097:blood
chemical_list: D000970:Antineoplastic Agents; D015415:Biomarkers; D009363:Neoplasm Proteins; D010750:Phosphoproteins; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D013844:Thiazoles; D019061:src-Family Kinases; D000069439:Dasatinib