title: Analytic and clinical validation of a prostate cancer-enhanced messenger RNA detection assay in whole blood as a prognostic biomarker for survival.
abstract: BACKGROUND
  Biomarkers based on detecting prostate cancer (PCa)-specific transcripts in blood are associated with inferior outcomes, but their validation in a clinical context is lacking.
  
  
  OBJECTIVE
  To determine whether detecting enhanced transcripts for PCa in whole blood using an analytically valid assay has prognostic significance relative to circulating tumor cell (CTC) enumeration.
  
  
  METHODS
  The detection of KLK3, KLK2, HOXB13, GRHL2, and FOXA1 in whole blood by reverse transcription polymerase chain reaction (RT-PCR) was studied in 97 men with metastatic castration-resistant PCa (mCRPC) as a prognostic factor for overall survival.
  
  
  METHODS
  The 2.5 ml of blood was collected in PAXgene tubes for total RNA extraction and 7.5 ml for CTC enumeration from patients with progressive mCRPC.
  
  
  METHODS
  PCa-enriched genes were detected using a sensitive RT-PCR assay in whole blood from patients with mCRPC. Analytical validity of the assay was established in a clinical laboratory environment. The frequency of detecting transcripts was compared to CTC enumeration using CellSearch in an independent data set and survival associations were explored by concordance probability estimate (CPE).
  
  
  CONCLUSIONS
  Two or more genes were detected by PCR in 53% of patients (51 of 97; 95% confidence interval [CI], 43-63%), and unfavorable CTC counts (five of more cells) were seen in 46% (45 of 97; 95% CI, 36-56%). Importantly, transcripts were detectable in 11 of 52 patients with favorable CTC counts (21%; 95% CI, 8-35%). Transcript detection predicted overall survival in a proportional hazards model. Significantly, the predictive accuracy of RT-PCR detection in combination with CTC enumeration had a CPE of 0.752 (standard error: 0.038), although this was limited by the number of patients evaluated.
  
  
  CONCLUSIONS
  This validated RT-PCR assay detecting prostate-specific RNA in whole blood is prognostic for survival and may assess patient risk in tandem with CellSearch CTC enumeration. Its clinical utility is being prospectively explored.
authors: Genitourinary Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY, USA; Department of Medicine, Weill Cornell Medical College, New York, NY, USA.
authors: Daniel C
authors: DC
authors: Danila
authors: Genitourinary Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors: Aseem
authors: A
authors: Anand
authors: Department of Computational Biology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors: Nikolaus
authors: N
authors: Schultz
authors: Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors: Glenn
authors: G
authors: Heller
authors: Department of Laboratory Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors: Mingliang
authors: M
authors: Wan
authors: Department of Laboratory Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors: Clifford C
authors: CC
authors: Sung
authors: Genitourinary Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors: Charles
authors: C
authors: Dai
authors: Department of Computational Biology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors: Raya
authors: R
authors: Khanin
authors: Department of Laboratory Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors: Martin
authors: M
authors: Fleisher
authors: Genitourinary Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY, USA; Department of Laboratory Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY, USA; Urology Service, Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY, USA; Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK.
authors: Hans
authors: H
authors: Lilja
authors: Genitourinary Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY, USA; Department of Medicine, Weill Cornell Medical College, New York, NY, USA. Electronic address: scherh@mskcc.org.
authors: Howard I
authors: HI
authors: Scher
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D004268:DNA-Binding Proteins / Q000235:genetics; D051541:Hepatocyte Nuclear Factor 3-alpha / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D007610:Kallikreins / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009360:Neoplastic Cells, Circulating; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000235:genetics; D064129:Prostatic Neoplasms, Castration-Resistant / Q000097:blood / Q000235:genetics* / Q000473:pathology*; D012333:RNA, Messenger / Q000097:blood*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015996:Survival Rate; D020840:Tissue Kallikreins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
chemical_list: D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; C496499:FOXA1 protein, human; C470830:GRHL2 protein, human; C484414:HOXB13 protein, human; D051541:Hepatocyte Nuclear Factor 3-alpha; D018398:Homeodomain Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; C549870:KLK3 protein, human; D007610:Kallikreins; D020840:Tissue Kallikreins; D017430:Prostate-Specific Antigen
keywords: Biomarker; Circulating tumor cells; Prostate cancer; Prostate-specific markers
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