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San Francisco, CA, JUNE 2, 2010–A nanotechnology-enabled prostate-specific antigen (PSA) test [Verisens™ PSA (RUO), Nanosphere, Inc.], 300 times more sensitive than conventional commercial tests, may be valuable in stratifying recurrence risk and monitoring a man’s response to adjuvant therapy following radical prostatectomy, according to new data from Northwestern University (NU). These data, which will be presented during the 105th Annual Scientific Meeting of the American Urological Association (AUA), will be shared with the media during a special session on Wednesday, June 2 at 9:30 a.m. PDT. William J. Catalona, MD, will present the data to the media during this session on behalf of the NU team that includes chemist and nanotechnologist Chad Mirkin, PhD, and Shad Thaxton, MD, PhD. J. Brantley Thrasher, MD, will moderate the session.

Using the Verisens™ PSA assay that uses gold nanoparticles to which PSA antibodies have been affixed, researchers tested specimens from more than 400 patients previously treated with radical prostatectomy with PSA values less than 0.1 ng/ml (usually considered an “undetectable” or essentially zero PSA level) and compared initial Verisens™ PSA values between men with and without clinical prostate cancer recurrence. They also compared  Verisens™ PSA values in patients with favorable tumor pathology (organ-confined disease, Gleason grade less than 7 and negative surgical margins, those with adverse pathology findings (seminal vesicle invasion, positive surgical margins, lymph node metastasis or a Gleason score greater than 7) and those who received adjuvant radiation treatment following radical prostatectomy. 

Data demonstrated that patients free of recurrence have initial Verisens™ PSA values significantly lower than those who subsequently developed tumor recurrence. In addition, patients with favorable tumor characteristics demonstrated lower Verisens™ PSA values than those with unfavorable characteristics. Finally, at first measurement, patients with unfavorable pathology who received adjuvant radiation therapy had the lowest mean PSAs of all patient groups, suggesting that adjuvant radiation is not only successful in eliminating residual cancer but also may reduce normal physiologic PSA production from the periurethral glands that are known to produce small amounts of PSA. These data confirm previous findings from the same lab, showing the increased sensitivity of nanotechnology-enabled PSA assays, and suggest that this test could ultimately be used as a post-radical prostatectomy PSA test to assess patient risk of tumor recurrence and the response to adjuvant therapy. 

“Our hope is that more sensitive PSA assays such as this one will allow clinicians to identify post-prostatectomy recurrences earlier in their course and ultimately direct adjuvant therapies,” said Dr. Thrasher, an AUA spokesman.

NOTE TO REPORTERS: Experts are available to discuss this study outside normal briefing times. To arrange an interview with an expert, please contact the AUA Communications Office at the number above or e-mail 

About the American Urological Association: Founded in 1902 and headquartered near Baltimore, Maryland, the American Urological Association is the pre-eminent professional organization for urologists, with more than 16,000 members throughout the world. An educational nonprofit organization, the AUA pursues its mission of fostering the highest standards of urologic care by carrying out a wide variety of programs for members and their patients.

Wendy Isett, AUA