Does ProsVue accurately identify men at minimal risk for disease progression?

The NADiA® ProsVue™ test is a highly sensitive investigational PSA immunoassay. Earlier pilot studies have shown that the ProsVue test data can be used to classify prostate cancer patients into those with no evidence of disease (NED) and those at risk for clinical progression (CP).

Moul et al. have now conducted a retrospective, multi-center clinical trial to further evaluate the potential prognostic value of ProsVue slope at a decision threshold of 2 pg/ml/month. (One nanogram or 1 ng = 1,000 picograms or 1,000 pg.)

The retrospective analysis was based on data from 392 prostate cancer patients who had been given radical prostatectomies between November 1991 and August 2001. To be eligible for this study, all of the following data had to be available from individual patients:

  • A first post-surgical PSA level of <100 pg/ml (i.e., <  0.1 ng/ml)
  • Full pathologic and radiographic data
  • Three frozen serum samples drawn between 6 weeks and 19.4 months post-surgery.

Patients were not eligible if they had received adjuvant radiotherapy and/or hormone therapy after surgery and prior to completion of the three post-surgical blood draws.

The results of this retrospective study showed that:

  • The average (median) PSA levels of the 392 patients was 6.3 ng/ml (range, 0 to 60.6 ng/ml)
  • The average (median) post-surgical Gleason score was 7.0 (range, 4 to 10).
  • 73 patients had received neoadjuvant hormone therapy prior to their surgery.
  • The pathologic stages of the patients were
    • pT0-2, n = 228
    • pT3, n = 147
    • pT4, n = 17
  • 116 patients had positive margins and 8 had positive lymph nodes.
  • The three post-surgical PSA values were based on serum drawn after median times of 4.9, 8.6, and 12.8 months and showed median values of 10.7, 23.0 and 50.7 pg/ml, respectively.
  • The sensitivity, specificity, PPV and NPV for a 2 pg/mL/month ProsVue slope were 75.0, 96.6, 81.4, and 95.2, respectively.
  • At a median follow-up of 10.5 years, 14 patients had died of prostate cancer and 40 had died overall.

The authors conclude the the ProsVue test “provides information previously unknown” in patients in the first year post-surgery, and that a ProsVue slope of  ≤ 2 pg/mL/month in that first year is highly associated with a lack of evidence of progression in long-term follow-up.

In theory, the ProsVue test may have some clinical value in the identification of patients who do not need long-term oncologic follow-up and in predicting the need for adjuvant radiation therapy. However, additional prospective studies will be necessary before this can be confirmed, and the practical clinical value of such a test would depend on whether it is significantly more accurate that data currently available from ultrasensitive PSA testing.

Additional information is available in a media release from the developer of the ProsVue test (IRIS International). According to that media release, the developer has submitted data to the FDA requesting approval to market this test.

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