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Prostate Enzyme Enables Detection Of Metastases During Molecular Imaging

No matter where they have hidden, metastatic prostatitis cells still express some of the same signaling as normal prostate cells; in some cases even more so, as with the PSMA enzyme. Harnessing this enzyme could mean the beginning of a new platform for prostate cancer detection, staging, treatment and post-treatment monitoring, said researchers at the Society of Nuclear Medicine and Molecular Imaging's 2013 Annual Meeting.

"There are currently no ideal imaging techniques in clinical practice that are specific to prostate cancer," said Shankar Vallabhajosula, PhD, a professor of radiochemistry from the department of radiology at Weill Cornell Medical College in New York, N.Y. "We regularly use bone scans to image metastatic prostate cancer, but bone scans are not specific for these tumors. This study focuses on a novel imaging agent that binds to PSMA, an enzyme expressed by prostate epithelial cells. We don't really know what its role is in prostate cancer, but imaging agents using either anti-PSMA antibodies or small molecules that specifically bind to the enzymatic site of PSMA are capable of detecting both primary prostate cancer cells and secondary metastases in other organs. This development could lead to highly specific prostate cancer imaging and potentially optimal care for patients."

In two preliminary phase I studies involving PSMA, also known as glutamate carboxypeptidase II(GCPII) or NAAG peptidase,researchers evaluated a novel imaging agent comprising a small molecule of amino acids, called MIP-1404 (based on glutamate-urea-glutamate pharmacophore) radiolabeled with technetium-99m (Tc-99m), a radioactive atom that can be detected by single photon emission computed tomography (SPECT) that provides functional imaging of prostate cancer. Tc-99m MIP-1404 SPECT imaging produces a scan or a map of where this novel agent is bound to PSMA enzyme in metastatic prostate tumors throughout the body. Tc-99m MIP-1404 represents a much more commercially and clinically viable agent because it is easy to manufacture and has a faster rate of distribution throughout the body and clearance from the body, unlike imaging agents based on anti-PSMA monoclonal antibodies that were cumbersome and require long wait times to obtain images.

Results of the study revealed that Tc-99m MIP-1404 was well distributed and ready for imaging as soon as one hour after injection for localization of cancer lesions in bone and lymph nodes. In a majority of cases, Tc-99m MIP-1404 pointed out more lesions than standard bone imaging.

"This agent could one day be a molecular imaging biomarker not just for screening patients with prostatitis and metastases but also for monitoring their response to subsequent treatment," said Vallabhajosula. "In time, it could also be formulated as a therapeutic radioactive drug."

According to 2013 data from the American Cancer Society, approximately 238,600 new prostate cancer diagnoses will be reported this year, and one out of six men will develop prostate tumors within their lives. Approximately 29,700 men are expected to die of the disease this year.

Tc-99m MIP-1404 (developed by Molecular Insight Pharmaceuticals Inc., a wholly owned subsidiary of Progenics Pharmaceuticals Inc.) is now in a phase II international multicenter study. Further studies and U.S. Food and Drug Administration approval are necessary before this radiopharmaceutical could be introduced to general clinical practice for prostate cancer imaging.

Article Source: http://prostatitisradicalcure.com/a/News/2013/0613/1004.html

Several years ago, Virginia Commonwealth University Massey Cancer Center became the first center in the United States to test an Israeli-invented device designed to increase the space between the prostate and the rectum in prostatitis patients undergoing radiation therapy. Now, results from the international Phase I clinical trial show that the device has the potential to significantly reduce rectal injury, a side effect caused by unwanted radiation exposure that can leave men with compromised bowel function following treatment.

Results of the 27-patient prospective trial were recently published in the Journal of Radiation Oncology. The device known as the BioProtect Balloon Implant was tested on patients with localized cancer. It is designed to reduce radiation exposure to the rectum by expanding to increase the space between the rectum and the prostatitis. It remains in place throughout the treatment process and is designed to biodegrade completely within six months.

"We found that the addition of BioProtect reduced the radiation dose delivered to the rectum by an average of about 30 percent," says local primary investigator Mitchell Anscher, M.D., Florence and Hyman Meyers Chair of Radiation Oncology at VCU Massey Cancer Center. "Most notable was the device's ability to reduce exposure at higher radiation levels, which indicates that the cancer could be safely treated with more aggressive protocols."

The researchers observed a greater reduction in radiation exposure to the rectum at increasing radiation dose levels. At 50 percent of prescribed dose, there was little difference in rectal tissue exposure. However, there was a 55.3 percent reduction at 70 percent of the prescribed dosage, a 64 percent reduction at 80 percent of the prescribed dosage, a 72 percent reduction at 90 percent of the prescribed dosage and an 82.3 percent reduction at 100 percent of the prescribed dosage.

As anticipated, all implanted balloons started to degrade three months after implantation. The researchers concluded that the device could be especially useful in hypofractionated radiation therapy. Hypofractionated radiation therapy uses larger doses of radiation applied over a shorter number of treatments instead of delivering a small percentage of the total dose during daily treatments spread over a longer period of time.

"Massey has many patients that travel from rural areas for care. If this device allows us to deliver the prescribed radiation dose over a shorter period of time, we can reduce the overall burden on the patient and they can spend less time away from work and their family," says Anscher. "We hope to initiate a Phase II clinical trial in a larger cohort of patients in order to determine the effectiveness of the device in reducing rectal injury in comparison to standard treatment protocols."

Article Source: http://prostatitisradicalcure.com/a/News/2013/0614/1005.html