title: A novel multiplex assay combining autoantibodies plus PSA has potential implications for classification of prostate cancer from non-malignant cases.
abstract: BACKGROUND
  The lack of sufficient specificity and sensitivity among conventional cancer biomarkers, such as prostate specific antigen (PSA) for prostate cancer has been widely recognized after several decades of clinical implications. Autoantibodies (autoAb) among others are being extensively investigated as potential substitute markers, but remain elusive. One major obstacle is the lack of a sensitive and multiplex approach for quantifying autoAb against a large panel of clinically relevant tumor-associated antigens (TAA).
  
  
  METHODS
  To circumvent preparation of phage lysates and purification of recombinant proteins, we identified B cell epitopes from a number of previously defined prostate cancer-associated antigens (PCAA). Peptide epitopes from cancer/testis antigen NY-ESO-1, XAGE-1b, SSX-2,4, as well as prostate cancer overexpressed antigen AMACR, p90 autoantigen, and LEDGF were then conjugated with seroMAP microspheres to allow multiplex measurement of autoAb present in serum samples. Moreover, simultaneous quantification of autoAb plus total PSA was achieved in one reaction, and termed the "A+PSA" assay.
  
  
  RESULTS
  Peptide epitopes from the above 6 PCAA were identified and confirmed that autoAb against these peptide epitopes reacted specifically with the full-length protein. A pilot study was conducted with the A+PSA assay using pre-surgery sera from 131 biopsy-confirmed prostate cancer patients and 121 benign prostatic hyperplasia and/or prostatitis patients. A logistic regression-based A+PSA index was found to enhance sensitivities and specificities over PSA alone in distinguishing prostate cancer from nonmalignant cases. The A+PSA index also reduced false positive rate and improved the area under a receiver operating characteristic curve.
  
  
  CONCLUSIONS
  The A+PSA assay represents a novel platform that integrates autoAb signatures with a conventional cancer biomarker, which may aid in the diagnosis and prognosis of prostate cancer and others.
authors.affiliation: Department of Urology, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, Los Angeles, CA 90095-1738, USA.
authors.forename: Chong
authors.initials: C
authors.lastname: Xie
authors.forename: Hyun J
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Haw
authors.forename: Anusha
authors.initials: A
authors.lastname: Kalbasi
authors.forename: Brian K
authors.initials: BK
authors.lastname: Gardner
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.forename: Jianyu
authors.initials: J
authors.lastname: Rao
authors.forename: David
authors.initials: D
authors.lastname: Chia
authors.forename: Monty
authors.initials: M
authors.lastname: Liong
authors.forename: Rubio R
authors.initials: RR
authors.lastname: Punzalan
authors.forename: Leonard S
authors.initials: LS
authors.lastname: Marks
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Pantuck
authors.forename: Alexandre
authors.initials: A
authors.lastname: de la Taille
authors.forename: Guomin
authors.initials: G
authors.lastname: Wang
authors.forename: Hideki
authors.initials: H
authors.lastname: Mukouyama
authors.forename: Gang
authors.initials: G
authors.lastname: Zeng
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000276:immunology; D001323:Autoantibodies / Q000276:immunology*; D015153:Blotting, Western; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D010455:Peptides / Q000276:immunology; D017430:Prostate-Specific Antigen / Q000276:immunology*; D011470:Prostatic Hyperplasia / Q000175:diagnosis / Q000276:immunology; D011471:Prostatic Neoplasms / Q000145:classification / Q000175:diagnosis* / Q000276:immunology*; D011472:Prostatitis / Q000175:diagnosis / Q000276:immunology; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000951:Antigens, Neoplasm; D001323:Autoantibodies; D018985:Epitopes, B-Lymphocyte; D010455:Peptides; C413656:XAGE1A protein, human; D017430:Prostate-Specific Antigen