Quanterix Corporation, Cambridge, MA.
Measurement of prostate specific antigen (PSA) in prostate cancer patients following radical prostatectomy (RP) has been hindered by the limit of quantification of available assays. Because radical prostatectomy removes the tissue responsible for PSA production, postsurgical PSA is typically undetectable with current assay methods. Evidence suggests, however, that more sensitive determination of PSA status following RP could improve assessment of patient prognosis and response to treatment and better target secondary therapy for those who may benefit most. We developed an investigational digital immunoassay with a 2-logs-lower limit of quantification than current ultrasensitive third-generation PSA assays.
We developed reagents for a bead-based ELISA for use with high-density arrays of femtoliter-volume wells. Anti-PSA capture beads with immunocomplexes and associated enzyme labels were singulated within the wells of the arrays and interrogated for the presence of enzymatic product. We characterized analytical performance, compared its accuracy with a commercially available test, and analyzed longitudinal serum samples from a pilot study of 33 RP patients.
The assay exhibited a functional sensitivity (20% interassay CV) < 0.05 pg/mL, total imprecision < 10% from 1 to 50 pg/mL, and excellent agreement with the comparator method. All RP samples were well within the assay measurement capability. PSA concentrations following surgery were found to be predictive of prostate cancer recurrence risk over 5 years.
The robust 2-log improvement in limit of quantification relative to current ultrasensitive assays and the validated analytical performance of the assay allow for accurate assessment of PSA status after RP.
Written by:
Wilson DH, Hanlon DW, Provuncher GK, Chang L, Song L, Patel PP, Ferrell EP, Lepor H, Partin AW, Chan DW, Sokoll LJ, Cheli CD, Thiel RP, Fournier DR, Duffy DC. Are you the author?
Reference: Clin Chem. 2011 Oct 13. Epub ahead of print.
doi: 10.1373/clinchem.2011.169540
PubMed Abstract
PMID: 21998342
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