An FDA advisory panel recommended the agency approve thesecond product from Cytogen Corp., a diagnostic imaging agent forprostate cancer.
The monoclonal antibody-based product, ProstaScint, targetsprostate-specific membrane antigen, thought to be associated withmore aggressive cancer. It is conjugated with the radioisotopeindium-111.
The Medical Imaging Drug Advisory Committee (MIDAC) wasunanimous in recommending ProstaScint be approved for use inprostate cancer patients who are suspected to have occult metastaticdisease. The product, to be used in conjunction with other diagnosticinformation, is useful in both the presurgical and recurrence settings.
"We are extremely pleased with MIDAC's recommendation as thereis a clear unmet medical need for additional information regardingthe location of a patient's prostate cancer," said Thomas McKearn,Cytogen's chairman, president and CEO. "Existing non-invasivediagnostic agents such as CT and MRI add little to the patient's orphysician's ability to predict whether the cancer has spread to areasoutside the prostatic bed and into the patient's lymph nodes. Thisinformation is critical in determining how best to manage a patient'sdisease."
Cytogen, of Princeton, N.J., plans to train nuclear medicinephysicians on proper use of the technology. The company expects toget a marketing partner with experience in the urology market.
"We've identified who we think are likely candidates and are tryingto establish a partnership now," said Pamela Murphy, Cytogen's vicepresident, corporate communications. "We have a strong group ofurologists behind this product."
Cytogen has run six clinical trials with ProstaScint involving morethan 600 patients. In the presurgical setting it showed a sensitivity of63 percent and specificity of 72 percent. In the recurrence settingsensitivity was 49 to 75 percent and specificity was 33 to 71 percent.
The positive predictive value was 50 to 68 percent and negativepredictive value was 42 to 70 percent. Accuracy, or the likelihood theresult is correct, was 60 to 62 percent.
Cytogen's other product on the market is OncoScint, a monoclonalantibody imaging agent used to detect colon and ovarian cancers.Murphy said ProstaScint "fills a more defined need" than OncoScint.A new drug application is on file for another product, Quadramet,which is designed to alleviate severe pain associated with cancers thathave metastasized in bone. n
-- Jim Shrine
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