Skip to Content

Protox Announces Positive Final Data from Prostate Cancer Study

VANCOUVER, Nov. 1 /CNW/ - Protox Therapeutics Inc. (TSX-V:PRX) today announced positive final results from its Phase 1 clinical trial evaluating PRX302 in patients with localized, recurrent prostate cancer following radiation failure. The trial results, an extension of those released on July 10, 2007, indicate that PRX302 is well tolerated and shows promising signs of therapeutic activity.

"In addition to demonstrating that PRX302 was well tolerated, early signs of therapeutic activity seen at this stage are promising," said Dr. Scott Coffield, Principal Investigator from the lead site, Scott and White Memorial Hospital. "These observations are encouraging and are suggestive of the potential clinical benefit of PRX302, particularly in light of the recurrent cancer seen in those patients who had progressive disease following radiation therapy."
This study was intended to examine the safety and tolerability of PRX302 as a primary endpoint and therapeutic activity as a secondary endpoint in patients with biopsy proven localized recurrent prostate cancer following radiation therapy who showed signs of disease progression as evidenced by rising levels of PSA (prostate specific antigen). A total of 24 patients were treated in this trial. The average age of patients in the study was 69.6 (range: 58-86).

Protox concluded that despite a 100-fold escalation in dose, the maximum tolerated dose (MTD) was not reached in this study while evidence of therapeutic activity was observed. As reported in July, no significant safety issues were encountered in this clinical trial. No serious adverse events were reported relating to PRX302 and most adverse events reported were associated with the injection procedure, rating no higher than Grade 1 (mild). Assessment of potential therapeutic activity was determined by prostate biopsies at  day-30 post-treatment and by measuring serial PSA levels.
A comparison of prostate biopsies taken at baseline and day-30 post-treatment showed that 18 of the 24 patients tested in this trial had a decrease in the percentage of cancer-positive biopsies. Three of the patients showed no detectable cancer in their day-30 biopsy. Results showed that in 21 of the 24 patients a decrease in PSA levels below screening levels were observed at 30 days or longer post-treatment while in 15 of 24 patients PSA levels continued to be below screening levels or stable at 90 days or longer. Comparison of PSA levels pre- and post-treatment showed a desirable trend towards an increase in PSA doubling time (PSADT) in 19 of 24 patients and a decrease or stable PSA velocity (PSAV) in 17 of 24 patients, both of which are positive outcomes for the patient.

"We are very pleased that the results from this Phase 1 study of PRX302 demonstrate its potential as a treatment for localized prostate cancer," said Dr. Samuel Denmeade, Chief Scientific Officer of Protox and co-inventor of PRX302. "These data, taken together with the encouraging interim data on our Phase 1 BPH study, further substantiate the promise of PRX302."
The company anticipates that a Phase 2a study evaluating PRX302 for the treatment of patients with locally recurrent prostate cancer following primary radiation therapy will commence before the end of the year. The objective of this study is to amplify the anti-cancer activity of PRX302 by using various intra-prostatic injection regimens. The assessment of therapeutic activity will be based on changes in PSA levels, PSAV, PSADT and tumor burden (prostate biopsies) following treatment. The study will also evaluate the safety and tolerability of the different regimens of injection.

Conference call

Protox will host a conference call and live webcast today at 11:00 a.m. E.T. to discuss these results. To access the conference call by telephone, dial 416-644-3420 or 1-800-733-7571. Please connect approximately ten minutes prior to the beginning of the call to ensure participation. The conference call will be archived for replay until November 8, 2007 at midnight. To access the archived conference call, dial 416-640-1917 or 1-877-289-8525 and enter the reservation number 21252499 followed by the number sign.
A live audio webcast of the conference call will be available at Please connect at least ten minutes prior to the conference call to ensure adequate time for any software download that may be required to join the webcast. The webcast will be archived at the above website for 30 days.

About Prostate Cancer

Prostate cancer is a leading cause of cancer death in North American men. One in every six men is diagnosed with prostate cancer during their lifetime. The American Cancer Society estimates that during 2007 approximately 219,000 new cases of prostate cancer will be diagnosed and over 27,000 men will die from the disease in the U.S. Current treatment options for localized prostate cancer include surgery and radiation therapy. Serious side effects are associated with these therapies including erectile dysfunction, incontinence, urinary dysfunction and bowel problems.

About Protox

Protox Therapeutics is a leader in advancing novel, targeted protein toxin therapeutics for the treatment of cancer and other proliferative diseases. Two novel drug candidates derived from the company's INxin(TM) and PORxin(TM) platforms are being developed in three clinical programs. A Phase 2a clinical trial evaluating PRX321 (INxin) for the treatment of primary brain cancer has been completed and the drug has received Fast Track Designation and Orphan Drug Status from the US FDA. Phase 1 clinical trials evaluating PRX302 (PORxin) have been completed for the treatment of localized prostate cancer and benign prostatic hyperplasia (enlarged prostate).


Certain statements included in this press release may be considered forward-looking. Such statements involve known and unknown risks, uncertainties and other factors that may cause actual results, performance or achievements to be materially different from those implied by such statements, and therefore these statements should not be read as guarantees of future performance or results. All forward-looking statements are based on Protox' current beliefs as well as assumptions made by and information currently
available to Protox and relate to, among other things, anticipated financial performance, business prospects, strategies, regulatory developments, market acceptance and future commitments. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this press release. Due to risks and uncertainties, including the risks and
uncertainties identified by Protox in its public securities filings; actual events may differ materially from current expectations. Protox disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.



/For further information: James Beesley, Director, Investor Relations,
Protox Therapeutics, (604) 688-0199,; Michael
Moore, Investor Relations, Equicom Group, (416) 815-0700 x 241,

Posted: November 2007